KR101543353B1 - display - Google Patents

Abstract

A display device includes: a substrate having a pixel region in which pixels are formed and a sensor region in which an optical sensor portion is formed; An illumination unit for illuminating the substrate from one side of the substrate; A thin film photodiode disposed in the sensor region and having at least a p-type semiconductor region and an n-type semiconductor region and receiving light incident from the other surface side of the substrate; And a thin film photodiode which is formed to face the thin film photodiode through an insulating film on the one surface side of the substrate so that the light generated from the illuminating unit is prevented from directly entering the thin film photodiode from the one surface side, Wherein a width of the P-type semiconductor region in a direction perpendicular to a direction connecting to the N-type semiconductor region in the thin film photodiode and a direction perpendicular to a direction connecting to the P-type semiconductor region The width of the N-type semiconductor region is different.

Description

DISPLAY DEVICE {DISPLAY}

The present invention relates to a display device having a substrate (display portion) having a pixel region in which pixels are formed and a sensor region in which a light receiving element is formed. More specifically, the present invention relates to a technique for improving utilization efficiency of light for receiving light reflected by a subject to be detected, which is in contact with or in proximity to a substrate (display portion), by a plurality of light receiving elements.

2. Description of the Related Art As a display device used in a mobile phone, a PDA, a digital still camera, a PC monitor, a television, and the like, a liquid crystal display device, an organic EL display device, a display device using an electrophoretic method and the like are known.

In accordance with the thinning of the display device, in addition to the original function of displaying the image and the character information, multifunctionality is demanded which combines the functions of an input device for inputting a user's instruction and the like. According to this demand, a display device is known which detects that a user's finger or a stylus pen (so-called touch pen or the like) touches or approaches the display screen.

The touch detection can be performed by, for example, a resistance film type or capacitive (capacitive) type touch panel. A display device is known in which a touch panel is added to a display surface side of a display panel such as a liquid crystal panel.

However, the addition of the touch panel is disadvantageous in that the display panel is thinned, and the cost is increased. In particular, the resistance film type touch panel has a problem that the resistance value change can be detected only when the screen is pressed with a certain degree of intensity, and the display surface is distorted. In addition, the resistance film type touch panel is a one-point detection type and its use is limited.

In recent years, in the liquid crystal display device, there is a movement to have a touch panel function by simultaneously forming an optical sensor on a transistor array substrate for controlling the voltage for driving the liquid crystal.

In a display device having an optical sensor on the above-described transistor array substrate, for example, a method of viewing a shadow of external light to recognize a finger or a stylus pen, or a method of reflecting light from a backlight, such as a finger or a stylus, Is known.

However, there is a problem that in the method of viewing the shadow of the external light to recognize the finger or the stylus pen, the function can not be accomplished in the dark place. On the other hand, in the method of reflecting the light from the backlight to a finger, stylus, or the like and detecting the reflected light, there is a problem that detection can not be performed in the case of complete black display.

With respect to such a background, Japanese Patent Application Laid-Open No. 2005-275644 (hereinafter referred to as Patent Document 1) proposes a liquid crystal display device which emits infrared rays from a backlight and detects the reflected light.

In Japanese Patent Application Laid-Open No. 2007-241303 (hereinafter referred to as Patent Document 2), a reflector is provided below a semiconductor layer made of polysilicon which constitutes a PIN diode, so that light is reflected to the semiconductor layer, A liquid crystal display device has been proposed which increases the length.

However, in the liquid crystal display device described in Patent Document 1, since there is a problem in that the absorptivity falls in the infrared region as compared with the visible region as shown in Fig. 1 in realizing the infrared sensor as a thin film polycrystalline silicon thin film, it's difficult. Further, since a visible light source is used for the backlight light source, there is a problem that when visible light having a high light sensitivity is incident on the photodiode, the infrared signal to be detected is buried in noise.

On the other hand, in the liquid crystal display device described in Patent Document 2, there is a problem that the light output increases but the sensitivity does not increase unless the capacity on the detection side is studied.

In addition to the above-mentioned problem regarding the improvement of the sensitivity of the sensor, the improvement of the saturation characteristic of the sensor is also required.

These problems are not limited to the liquid crystal display devices disclosed in Patent Documents 1 and 2, but are also common to other display devices such as organic EL display devices and display devices using electrophoresis.

Therefore, a problem to be solved is that it is difficult to improve the detection sensitivity of the sensor and the saturation characteristics of the sensor.

According to the embodiment of the present invention, a display device includes: a substrate having a pixel region in which pixels are formed and a sensor region in which an optical sensor portion is formed; An illumination unit for illuminating the substrate from one side of the substrate; A thin film photodiode disposed in the sensor region and having at least a p-type semiconductor region and an n-type semiconductor region and receiving light incident from the other surface side of the substrate; And a thin film photodiode which is formed to face the thin film photodiode through an insulating film on the one surface side of the substrate so that the light generated from the illuminating unit is prevented from directly entering the thin film photodiode from the one surface side, Wherein a width of the P-type semiconductor region in a direction perpendicular to a direction connecting to the N-type semiconductor region in the thin film photodiode and a direction perpendicular to a direction connecting to the P-type semiconductor region The width of the N-type semiconductor region is different.

A display device according to an embodiment of the present invention has a substrate, an illumination portion, a thin film photodiode, and a metal film.

The substrate has a pixel region in which pixels are formed and a sensor region in which an optical sensor section is included.

The illumination unit illuminates the substrate from one side of the substrate.

The thin film photodiode is disposed in the sensor region and has at least a p-type semiconductor region and an n-type semiconductor region, and receives light incident from the other surface side of the substrate.

The metal film is formed so as to face the thin film photodiode through an insulating film on one side of the substrate, and light generated from the illuminating portion is prevented from directly entering the thin film photodiode from one side, and is fixed at a predetermined potential.

Here, in the thin film photodiode, the width of the N-type semiconductor region in the direction perpendicular to the direction connecting to the N-type semiconductor region and the direction perpendicular to the direction connecting the P-type semiconductor region And are formed in different layouts.

According to another embodiment of the present invention, a display device includes: a substrate having a pixel region where pixels are formed and a sensor region in which an optical sensor portion is formed; An illumination unit for illuminating the substrate from one side of the substrate; A thin film photodiode disposed in the sensor region and having at least a p-type semiconductor region and an n-type semiconductor region and receiving light incident from the other surface side of the substrate; And a thin film photodiode which is formed to face the thin film photodiode through an insulating film on the one surface side of the substrate so that the light generated from the illuminating unit is prevented from directly entering the thin film photodiode from the one surface side, Wherein a capacitance value of a parasitic capacitance formed by the P-type semiconductor region and the metal film opposed to each other through the insulating film in the thin film photodiode and the metal film is larger than a capacitance value of the parasitic capacitance Type semiconductor region and the capacitance of the parasitic capacitance formed by the N-type semiconductor region and the metal film.

A display device according to another embodiment of the present invention has a substrate, an illumination portion, a thin film photodiode, and a metal film.

The substrate has a pixel region in which pixels are formed and a sensor region in which a photosensor portion is formed.

The illumination unit illuminates the substrate from one side of the substrate.

The thin film photodiode is disposed in the sensor region and has at least a p-type semiconductor region and an n-type semiconductor region, and receives light incident from the other surface side of the substrate.

The metal film is formed so as to face the thin film photodiode through an insulating film on one side of the substrate, and light generated from the illuminating portion is prevented from directly entering the thin film photodiode from one side, and is fixed at a predetermined potential.

Here, in the thin film photodiode and the metal film, the capacitance value of the parasitic capacitance constituted by the P-type semiconductor region and the metal film opposed to each other through the insulating film is composed of the N-type semiconductor region and the metal film opposed to each other through the insulating film Which is different from the capacitance value of the parasitic capacitance.

According to another aspect of the present invention, there is provided a display device including: a substrate having a pixel region in which pixels are formed and a sensor region in which an optical sensor unit is formed; an illumination unit that illuminates the substrate from one side of the substrate; A thin film photodiode disposed in the sensor region and having at least a p-type semiconductor region and an n-type semiconductor region and receiving light incident from the other surface side of the substrate; And a thin film photodiode which is formed to face the thin film photodiode through an insulating film on the one surface side of the substrate so that the light generated from the illuminating unit is prevented from directly entering the thin film photodiode from the one surface side, Wherein an area of a region where the P-type semiconductor region and the P-type semiconductor region overlap with each other when viewed from the one surface side or the other surface side in the thin film photodiode is larger than an area of the N-type semiconductor region and the metal Is different from the area of the overlapped region of the film.

A display device according to another embodiment of the present invention has a substrate, an illumination portion, a thin film photodiode, and a metal film.

The substrate has a pixel region in which pixels are formed and a sensor region in which a photosensor portion is formed.

The illumination unit illuminates the substrate from one side of the substrate.

The thin film photodiode is disposed in the sensor region and has at least a p-type semiconductor region and an n-type semiconductor region, and receives light incident from the other surface side of the substrate.

The metal film is formed so as to face the thin film photodiode through an insulating film on one side of the substrate, and light generated from the illuminating portion is prevented from directly entering the thin film photodiode from one side, and is fixed at a predetermined potential.

Here, in the thin film photodiode, the area of the region where the P-type semiconductor region overlaps with the metal film when viewed from the one surface side or the other surface side is different from the area of the overlapping region of the N-type semiconductor region and the metal film.

According to the display device of the embodiment of the present invention, in the thin film photodiode formed in the sensor region of the substrate, the width of the p-type semiconductor region and the width of the n-type semiconductor region are made different. As a result, the parasitic capacitance between the thin film photodiode and the metal film can be reduced to improve the detection sensitivity of the sensor and improve the saturation characteristics of the sensor.

In the display device according to another embodiment of the present invention, the capacitance value of the parasitic capacitance formed by the P-type semiconductor region and the metal film opposed to each other through the insulating film is larger than the capacitance value of the N-type semiconductor region, Which is different from the capacitance value of the parasitic capacitance. As a result, the parasitic capacitance between the thin film photodiode and the metal film can be reduced to improve the detection sensitivity of the sensor and improve the saturation characteristics of the sensor.

In the display device according to another embodiment of the present invention, the area of the region where the P-type semiconductor region overlaps with the metal film when viewed from the one surface side or the other surface side is larger than the area of the N-type semiconductor region and the metal film Is different from the area of the overlap region. As a result, the capacitance value of the parasitic capacitance formed by the P-type semiconductor region and the metal film opposed to each other through the insulating film is different from the capacitance value of the parasitic capacitance formed by the N-type semiconductor region and the metal film opposed to each other through the insulating film And the parasitic capacitance between the thin film photodiode and the metal film is reduced to improve the detection sensitivity of the sensor and also to improve the saturation characteristics of the sensor.

Hereinafter, a display device according to an embodiment of the present invention will be described with reference to the drawings.

The description is made in the following order.

(1) First Embodiment (Configuration in which the width of the anode region in the direction perpendicular to the direction of connection to the cathode region is different from the width of the cathode region in the direction perpendicular to the direction of connection to the anode region)

(2) Variations

(3) Second Embodiment (Configuration in which an extension part for extending in a direction perpendicular to the direction of connection to the cathode region is provided outside the overlapping region with the control gate)

(4) Third Embodiment (Configuration with I-region portion having the width equal to the width of the anode region at the anode region end of the I-region)

(5) Fourth Embodiment (Configuration in which the overlapping width of the P ⁺ region and the control gate is narrower than the overlapping width of the N ⁺ region and the control gate)

(6) Fifth Embodiment (Application example of display device)

≪ Embodiment 1 >

Hereinafter, a liquid crystal display device as a display device according to the first embodiment will be described as a main example with reference to the drawings.

The display device of the present embodiment can be suitably applied to a so-called " transmissive type "liquid crystal display device in which light is irradiated from the back side (the surface opposite to the front side for performing image display) of the substrate serving as the display portion. Therefore, in the following description, it is assumed that the liquid crystal display device is a transmissive type.

(Total configuration)

Fig. 1 shows a schematic overall configuration of a transmissive liquid crystal display device.

The liquid crystal display 100 shown in Fig. 1 has, for example, a liquid crystal panel 200 as a display portion as a "substrate " and a data processing portion 400 as a backlight 300 as an" illumination portion ".

1, the liquid crystal panel 200 has a TFT array substrate 201, a color filter substrate 202 as a so-called "counter substrate ", and a liquid crystal layer 203. [ Hereinafter, the side of the backlight 300 in the thickness direction of the liquid crystal panel 200 is referred to as a "one surface side" or a "back surface side" Side is referred to as the "other surface side" or the "front surface side ".

For example, the TFT array substrate 201 and the color filter substrate 202 face each other with a gap therebetween, and the liquid crystal layer 203 is formed so as to be sandwiched between the TFT array substrate 201 and the color filter substrate 202 Respectively. Although not specifically shown, alignment films for aligning the alignment direction of the liquid crystal molecules of the liquid crystal layer 203 are formed in pairs so as to hold the liquid crystal layer 203 therebetween. A color filter 204 is formed on the surface of the color filter substrate 202 on the liquid crystal layer 203 side.

For example, the first polarizing plate 206 and the second polarizing plate 207 are provided so as to face each other on both sides of the liquid crystal panel 200. Specifically, the first polarizing plate 206 is disposed on the back side of the TFT array substrate 201, and the second polarizing plate 207 is disposed on the front side of the color filter substrate 202.

For example, on the rear surface side of the TFT array substrate 201 facing the liquid crystal layer 203, the optical sensor unit 1 is provided as shown in Fig. The optical sensor unit 1 includes a thin film photodiode which is a light receiving element and its readout circuit, which will be described in detail later.

The optical sensor unit 1 is formed so as to provide a function of a so-called touch panel in the liquid crystal panel 200 as well. For example, when the liquid crystal panel 200 is viewed from the display surface (front surface) side, it is regularly arranged in the effective display area PA.

Fig. 1 shows a cross section of a liquid crystal panel 200 in which an optical sensor unit 1 is arranged in a matrix in an effective display area PA. For example, in Fig. 1, a plurality of (four on the drawing) optical sensor units 1 are arranged at regular intervals. Although FIG. 1 shows four optical sensor units 1 for the sake of convenience, it is not limited thereto.

When the function of position detection is limited to a part of the effective display area PA, for example, the optical sensor unit 1 is regularly arranged in the limited display area.

1, the area of the liquid crystal panel 200 on which the photosensor unit 1 is formed is referred to as the "sensor area PA2" in the effective display area PA of the display plane (front surface) The area of the pixel region 200 is defined as "pixel region PA1 ". The pixel region PA1 is an arrangement region of pixels in which a plurality of colors such as red (R), green (G), and blue (B) are allocated for each pixel. The color assignment is determined by the transmission wavelength characteristic of the color filter to which the pixel opposes.

For example, although not shown in Fig. 1, a pixel electrode and a common electrode (also referred to as a counter electrode) are formed in a pixel arrangement area (pixel area PA1). The pixel electrode and the common electrode are formed of a transparent electrode material. A common electrode common to all the pixels may be formed on the other surface side (liquid crystal layer side) of the TFT array substrate 201 on the side of the semi-liquid crystal layer of the pixel electrode opposite to the pixel electrode. Alternatively, pixel electrodes are formed on the rear surface side of the TFT array substrate 201, common electrodes are sandwiched by the liquid crystal layer 203, and are formed on the color filter substrate 202 side in common to all the pixels There is a case.

Although not shown in Fig. 1, in the arrangement region of the pixels, an auxiliary capacitance for assisting the liquid crystal capacitance between the pixel electrode and the counter electrode in accordance with the pixel configuration, and an application potential to the pixel electrode are controlled in accordance with the potential of the input video signal A switching element or the like is also formed.

For example, when a unit composed of a plurality of pixels corresponding to a plurality of colors one by one is referred to as a "pixel unit", when the ratio of the number of the optical sensor units 1 to the pixel units is 1: 1, The arrangement density of the substrate 1 becomes maximum. In this embodiment, the arrangement density of the photosensor portion 1 may be the maximum or the smaller.

For example, a backlight 300 is disposed on the rear surface side of the TFT array substrate 201. The backlight 300 faces the back surface of the liquid crystal panel 200 and emits illumination light to the effective display area PA of the liquid crystal panel 200. [

The backlight 300 illustrated in FIG. 1 has a light source 301 and a light guide plate 302 that converts light emitted from the light source 301 into light having a surface light by diffusing the light. The backlight 300 has a side light type, an undernut type, and the like depending on the arrangement position of the light source 301 with respect to the light guide plate 302, but the sidelight type is exemplified here.

For example, the light source 301 is disposed on one side or both sides of the liquid crystal panel 200 behind and behind the liquid crystal panel 200. In other words, the light source 301 is disposed along one side of the liquid crystal panel 200 viewed from the display surface 200A (front side), or two sides opposite to each other. However, the light source 301 may be disposed along three or more sides of the liquid crystal panel 200.

The light source 301 is constituted by, for example, a cold cathode lamp that converts ultraviolet rays generated by arc discharge in a low-pressure mercury vapor in a glass tube into visible light by a phosphor and emits it, or an LED or an EL element. 1 shows a case where a visible light source 301a such as a white LED and an IR light source 301b are arranged at two opposing sides as a light source 301. [

The light guide plate 302 is made of, for example, a translucent acrylic plate, and is disposed on the light guide plate 302 along the surface (from one side to the other side in the direction along the back surface of the liquid crystal panel 200) Light guide. A dot pattern (a plurality of protrusions), not shown, formed integrally with the light guide plate 302 or formed by a member different from the light guide plate 302 is provided on the back surface of the light guide plate 302, for example. The light guided is scattered according to the dot pattern and irradiated to the liquid crystal panel 200. A reflective sheet for reflecting light may be provided on the back side of the light guide plate 302, and a diffusion sheet or a prism sheet may be provided on the front side of the light guide plate 302.

For example, the backlight 300 has the above-described configuration and is configured to irradiate substantially uniform planar light to the entire surface of the effective display area PA of the liquid crystal panel 200. [

1, the data processing unit 400 includes a control unit 401 and a position detection unit 402. [ The data processing unit 400 includes a computer, and operates by a computer controlling each unit by a program. Therefore, the functions of the control unit 401 and the position detection unit 402 are realized by using a task or data of a program stored in advance in a memory (not shown) or inputted from the outside.

The data processing unit 400 may be implemented by dividing its function into and out of the liquid crystal panel 200. [ 1 illustrates a case where the data processing unit 400 is disposed outside the liquid crystal panel 200, for example, as a single or a plurality of ICs.

For example, the control unit 401 performs control of image display, control of an IR sensor (data collection by light reception), and backlight control for position detection.

Regarding image display, the control unit 401 controls the image display of the liquid crystal panel 200, for example, by giving instructions to the display driving circuit in the liquid crystal panel 200 collectively. Regarding the control of the IR sensor, the control unit 401 controls the detection of the position (and the size) of the object to be detected by collectively giving, for example, a sensor driving circuit in the liquid crystal panel 200. Examples of the display drive circuit and the sensor drive circuit will be described later.

Regarding the backlight control, the control unit 401 controls the brightness of the illumination light output from the backlight 300 by supplying a control signal to the power supply unit (not shown) of the backlight 300. [

For example, the position detection section 402, when receiving an instruction from the control section 401, detects whether or not a detection target such as a user's finger or a stylus pen touches or is moved in accordance with the light reception data sent through the sensor drive circuit in the liquid crystal panel 200 And detects a close position. This detection is performed for the effective display area PA of the liquid crystal panel 200. [

(Schematic Configuration of Liquid Crystal Panel)

2 is a block diagram showing a configuration example of a driving circuit in the liquid crystal panel.

For example, as shown in Fig. 2, the liquid crystal panel 200 has a display unit 10 in which pixels PIX are arranged in a matrix.

1, the peripheral area CA exists around the effective display area PA. The peripheral area CA refers to an area other than the effective display area PA of the TFT array substrate 201. [ In the peripheral region CA, as shown in Fig. 2, a driving circuit is formed which is represented by several functional blocks including a TFT formed in a lump with the TFTs in the effective display region PA.

For example, the liquid crystal panel 200 includes a vertical driver (VDRV) 11, a display driver (D-DRV) 12, a sensor driver (S-DRV) A switch array SEL.SW. 14, and a DC / DC converter (DC / DC. CNV.

For example, the vertical driver 11 is a circuit having functions such as a shift register for scanning various control lines wired in the horizontal direction in the vertical direction for selecting the pixel lines.

The display driver 12 is a circuit having a function of sampling the data potential of the video signal to generate the data signal amplitude and discharging the data signal amplitude to the signal line common to the pixels in the column direction.

The sensor driver 13 performs scanning of the control line such as the vertical driver 11 and detection of the sensor output (detection) in synchronism with the scanning of the control line, with respect to the photosensor unit 1 dispersed and disposed in the pixel arrangement area at a predetermined density, Data).

The switch array 14 is composed of a plurality of TFT switches and is a circuit for controlling emission of the data signal amplitude by the display driver 12 and controlling the sensor output from the display unit 10. [

The DC / DC converter 15 is a circuit for generating various DC voltages of a potential necessary for driving the liquid crystal panel 200 from an input power supply voltage.

For example, the input / output signals of the display driver 12 and the sensor driver 13 and other signals are exchanged in and out of the liquid crystal panel 200 through the flexible substrate 16 provided in the liquid crystal panel 200 .

For example, in addition to the configuration shown in Fig. 2, a configuration for generating a clock signal or for external input is also included in the drive circuit.

(Example of combination of pixel and optical sensor unit)

As described above, for example, the pixel and the photosensor section are regularly arranged in the effective display area PA. The arrangement is arbitrary, but a plurality of sets of pixels and one optical sensor unit are set, and a plurality of sets are arranged in a matrix form in the effective display area PA. For example, three pixels of R, G, and B and one optical sensor unit 1 are set as one set.

For example, the color filter 204 shown in Fig. 1 has a filter that substantially corresponds to the size when viewed in the plane of the pixel PIX and selectively transmits the respective wavelength regions of R, G, and B, And has a black matrix that shields the periphery of the filter (all boundaries) with a constant width for prevention.

(Pattern and cross-sectional structure of the pixel portion and the photosensor portion)

Fig. 3A shows an example of a plan view of the photosensor section 1, and Fig. 3B shows an example of an equivalent circuit of the photosensor section 1 corresponding to the pattern of Fig. 3A.

For example, as shown in FIG. 3B, the photosensor section 1 has three transistors formed of an N-channel type thin film transistor (TFT) and a thin film photodiode PD as a light receiving element.

The three transistors are the reset transistor TS, the amplifier transistor TA, and the read transistor TR.

For example, the thin film photodiode PD is formed as a light receiving element having sensitivity to non-visible light such as infrared light or ultraviolet light. In the present embodiment, the IR light source 301b constituting the backlight 300 described above is a light receiving element having sensitivity to the infrared light generated. When the backlight emits ultraviolet light, the thin film photodiode PD is designed to have sensitivity to the ultraviolet light.

For example, in the thin-film photodiode PD, the anode is connected to the storage node SN and the cathode is connected to a supply line (hereinafter referred to as "VDD line") 31 of the power source voltage VDD.

The thin film photodiode PD has a PIN structure or a PDN structure as will be described later and has a structure in which an I (intrinsic) region (an intrinsic semiconductor region of a PIN structure) or a D (doped) region (an N ^- region of a PDN structure) And a control gate CG for applying an electric field. The thin-film photodiode PD is reverse-biased and used, and the degree of depletion at that time is controlled by the control gate CG so that the sensitivity can be optimized (usually maximized).

For example, the reset transistor TS has a drain connected to the storage node SN, a source connected to a supply line (hereinafter referred to as "VSS line") 32 of a reference voltage VSS through a wiring 37, (Hereinafter referred to as "reset line" The reset transistor TS switches the storage node SN from the floating state to the connection state to the VSS line 32, discharges the storage node SN, and resets the accumulated charge amount.

For example, the drain of the amplifier transistor TA is connected to the VDD line 31, and the source thereof is connected to the output line (hereinafter, detection line) 35 of the detection potential Vdet (or detection current Idet) through the read transistor TR , And a gate is connected to the storage node SN.

For example, in the read transistor TR, the drain is connected to the source of the amplifier transistor TA, the source is connected to the detection line 35, and the gate is connected to a supply line (hereinafter referred to as a lead control line) 34 .

For example, the amplifier transistor TA has an action of amplifying the accumulated charge amount (light reception potential) when a static charge generated in the thin film photodiode PD accumulates in the storage node SN which is put into the floating state again after resetting. The read transistor TR is a transistor for controlling the timing of discharging the light receiving potential amplified by the amplifier transistor TA to the detection line 35. [ When the accumulation time of a predetermined time elapses, the read control signal READ is activated to turn on the read transistor TR, so that the amplifier transistor TA is supplied with a voltage at the source and the drain, and a current corresponding to the gate potential at that time flows do. As a result, a potential change in which the amplitude increases in response to the light receiving potential appears on the detection line 35, and this potential change is output from the detection line 35 to the outside of the photosensor section 1 as the detection potential Vdet. Alternatively, a detection current Idet whose value varies according to the light receiving potential is output from the detection line 35 to the outside of the optical sensor unit 1. [

Fig. 3A shows a top view of the TFT array substrate 201 before it is attached to the color filter substrate 202 as shown in Fig. 1 and the liquid crystal is sealed.

In the pattern diagram shown in Fig. 3A, the elements and nodes shown in Fig. 3B are given the same reference numerals, so that the electrical connection between the elements is obvious.

For example, the VDD line 31, the VSS line 32 and the detection line 35 are formed of a wiring layer of aluminum (AL), and the reset line 33 and the lead control line 34 are formed of a gate metal GM ), For example, molybdenum (Mo). The gate metal (GM) is formed below the wiring layer of aluminum (AL). Four semiconductor layers such as a polysilicon (PS) layer and the like are disposed in an upper layer than the gate metal (GM) and a layer lower than the aluminum (AL). The reset transistor TS, the read transistor TR, the amplifier transistor TA, and the thin film photodiode PD each have a semiconductor layer such as a PS layer.

For example, in a transistor, a transistor structure in which an N-type impurity is introduced into one and other portions of a thin film semiconductor layer composed of a PS layer or the like intersecting with a gate metal (GM) to form a source and a drain .

On the other hand, in the thin film photodiode PD, P-type and N-type impurities of opposite conductivity type are introduced into one side and the other side of the thin film semiconductor layer 36 made of a PS layer or the like, The P-type impurity region (P ⁺ region) becomes the anode (A) region of the thin film photodiode PD, and this constitutes, for example, a storage node SN. On the other hand, the N-type impurity region (N ⁺ region) constitutes the cathode (K) region of the thin film photodiode PD, which is connected to the VDD line 31 in the upper layer via, for example, a contact.

Fig. 4 is a cross-sectional view schematically showing a part of the pixel PIX of the liquid crystal sensor of the FFS type and the optical sensor unit 1. Fig. Fig. 4 shows a cross section showing a part of the photosensor section 1 along the line S1-S1 in Fig. 3A and a cross section of a part of the pixel PIX (not shown).

For example, the pixel of the liquid crystal of this embodiment is an FFS (Field Fringe Switching) method. The FFS type liquid crystal is also referred to as an " In Plane Switching (IPS) -Pro "type liquid crystal.

As shown in Fig. 4, a transistor serving as a switching element SW is formed by embedding in a multilayer insulating film on a TFT array substrate 201. [ The insulating film shown in Fig. 4 includes a two-layered gate insulating film 50, a two-layered first interlayer insulating film 51, a second interlayer insulating film (planarizing film) 52, a third interlayer insulating film 53, .

For example, a gate metal GM made of molybdenum (Mo) or the like and serving as a vertical scanning line 44 is formed directly below the gate insulating film 50, and a polysilicon (PS) layer A semiconductor layer 43 of a thin film is formed.

In the semiconductor layer 43, a P ^- region which is a channel formation region is located above the gate metal GM, and an N ⁺ region which serves as a source / drain is formed on both sides of the P ^- region.

For example, a pixel electrode 40 formed of a transparent electrode layer separated for each pixel through the internal wiring 42 and the contact 41 is formed on one side of the source and the drain formed in the semiconductor layer 43.

A common electrode 55 is formed on the interface between the second interlayer insulating film 52 and the third interlayer insulating film 53 below the pixel electrode 40 so as to face the pixel electrode 40. The common electrode 55 is formed of a transparent electrode layer common to all the pixels.

Further, a signal line 45A made of aluminum or the like is connected to the other side of the source and the drain of the semiconductor layer 43.

For example, the color filter substrate 202 can be laminated above the TFT array substrate 201, and a liquid crystal layer 203, an orientation film 56, and a color filter 204 are formed between the two substrates from the lower layer Respectively.

Here, the liquid crystal layer 203 is composed of a nematic liquid crystal. The common electrode 55 is fixed to the common potential and is an electrode for changing the electric field applied to the liquid crystal by the voltage applied between the pixel electrodes 40. [

1, the first polarizing plate 206 and the second polarizing plate 207, which are provided in close contact with each other through an adhesive on the outer surfaces of the TFT array substrate 201 and the color filter substrate 202, (Close-Nicol state).

The material of the signal line 45A and the vertical scanning line 44 (gate metal GM) may be aluminum (Al), molybdenum (Mo), chromium (Cr), tungsten (W), titanium (Ti) Pb), a composite layer thereof (for example, Ti / Al), or an alloy layer thereof.

Next, the sectional structure of the optical sensor unit 1 will be described.

4, the thin film photodiode PD includes a gate insulating film 50 of two layers on the TFT array substrate 201, a first interlayer insulating film 51 of two layers, a second interlayer insulating film (planarizing film) 52 ), And a third interlayer insulating film 53, as shown in Fig.

For example, a control gate CG, which is a "metal film" is formed immediately below the gate insulating film 50, and a thin semiconductor film 36 made of polysilicon or the like is formed on the gate insulating film 50.

The semiconductor layer 36 has an I-region (intrinsic semiconductor region) 36I above the control gate CG and has an anode region 36A made of P ⁺ region (P-type semiconductor region) and N ^{And a} cathode region 36K composed of a ⁺ region (N-type semiconductor region). In this embodiment, a low concentration semiconductor region (N-region) 36N containing low concentration N-type impurity is provided between the I-region 36I and the cathode region 36K. Thus, a thin film photodiode having a PIN structure having a low concentration semiconductor region is formed.

In the case of the PDN structure, a D region (N-region) is formed instead of the I-region.

The negative electrode region 36K is connected to the VDD line 31 formed on the first interlayer insulating film 51 by the contact plug 54 formed in the first interlayer insulating film 51. For example, The anode region 36A is connected to the wiring 39 at a position not shown in the figure, and is connected to the gate electrode of the amplifier transistor TA.

The detection line 35 and the VSS line 32 are arranged side by side on the first interlayer insulating film 51 at a position apart from the VDD line 31. [

For example, since the VDD line 31, the VSS line 32 and the detection line 35 are all made of aluminum or the like and have a large step, a second interlayer insulating film (planarization film) 52 for leveling the level difference is formed .

On the second interlayer insulating film 52, a common electrode 55 fixed at a common potential is formed. Since the optical sensor section 1 has no pixel electrode, the electric field applied to the liquid crystal can not be controlled, but has a role of fixing the liquid crystal by the common electrode 55. [ Since the common electrode 55 is formed of a transparent electrode layer, it can transmit light.

4, in the color filter 204, a black matrix 21K is formed at a boundary portion between the photosensor portion 1 and the pixel PIX, and a sensor opening portion SA is provided between the two black matrices 21K have. On the other hand, in the pixel PIX, any one of R, G, and B filters is shown.

(Structure and Photoreceptive Characteristics of Thin Film Photodiode PD)

5A is a plan view of the thin-film photodiode PD having a PIN structure, and FIG. 5B is a cross-sectional view taken along the line X-X 'in FIG. 5A. 5B, the wiring of the VDD line 31 and the like and the structure of the upper layer than the second interlayer insulating film 52 are omitted.

For example, a control gate 38 made of a "metal film " is formed on the TFT array substrate 201, a two-layer gate insulating film 50 is formed on the control gate 38, Respectively.

The semiconductor layer 36 has a pattern shape shown in Fig. 5A. Specifically, P ⁺ regions formed in the anode region (P-type semiconductor region) (36A), I- domain (an intrinsic semiconductor region) (36I), the low-concentration semiconductor region of the low concentration semiconductor region (N- region) (36N), N ⁺ And a cathode region 36K made of a region (N-type semiconductor region) are laid out. Thus, a thin film photodiode having a PIN structure having a low concentration semiconductor region is formed.

In the case of the PDN structure, a D region (N-region) is formed instead of the I-region.

The layout of the control gate 38 for each of the above-described regions is shown in Fig. 5A.

The first interlayer insulating film 51 is formed covering the photodiode described above and connected to the contact plug 54 through the contact hole CT leading to the anode region 36A and the cathode region 36K.

In the above-described photodiode, when a reverse bias is applied, the depletion layer is spread inside the I-region (or the D region). Back gate control (electric field control by the control gate CG) is performed in order to promote the depletion. However, in the PIN structure, the depletion is about 10 mu m from the P ⁺ region. However, in the PDN structure, approximately the entire region of the D region is depleted and the area having the light receiving sensitivity is advantageously large. In this embodiment, either the PIN structure or the PDN structure can be employed.

The thin film photodiode PD as the position sensor having such a structure is designed to have sensitivity to non-visible light, preferably a sensitivity peak.

The non-visible light includes, for example, infrared light or ultraviolet light. In the International Commission on Illumination (CIE), the boundary between wavelengths of ultraviolet light (which is also an example of non-visible light) and visible light is 360 nm to 400 nm, the boundary between wavelengths of visible light and infrared light is 760 nm - 830 nm. Practically, ultraviolet light having a wavelength of 350 nm or less and infrared light having a wavelength of 700 nm or more may be used. Here, the wavelength range of the non-visible light is 350 nm or less and 700 nm or more. However, in this embodiment, the boundary of the wavelength of the invisible light may be arbitrarily defined within the range of 360 nm to 400 nm and 760 nm to 830 nm.

When the infrared light (IR light) is used as the nonvisible light, the thin semiconductor layer 36 constituting the thin film photodiode PD having the sensitivity peak in the IR light has an energy band gap (for example, 1.6 eV). For example, the thin film photodiode PD may be formed of polycrystalline silicon having an energy band gap of 1.1 eV between a valence band and a conduction band and a value smaller than an energy band gap (for example, 1.6 eV) of a light receiving element of visible light, .

The energy band gap Eg is calculated from Eg = hv (h is Planck's constant, v = 1 /? (Where? Is the wavelength of light)).

On the other hand, when a thin semiconductor layer 36 is formed from amorphous silicon or microcrystalline silicon, these semiconductor materials have a distribution in the energy band gap level. Therefore, even in the case of infrared rays and ultraviolet rays, . Therefore, the thin film photodiode PD formed of these semiconductor materials has a light receiving capability not only for visible light, but also for non-visible light such as infrared light and ultraviolet light, thereby making it available as a light receiving element for visible light and invisible light.

From the above, it is preferable that the thin film photodiode PD, which can be preferably used in the present embodiment, is formed of polycrystalline silicon, microcrystalline silicon, amorphous silicon, or crystalline silicon.

In any case, the thin film photodiode PD in this embodiment is designed and designed so that the absorption coefficient of the non-visible light such as infrared light or ultraviolet light becomes larger than that of the photodiode designed for receiving visible light.

Here, with reference to FIG. 3, the light detection operation of the photosensor section including the above-described thin film photodiode will be examined.

When the method of accumulating the current generated by the light irradiation to the thin film photodiode in the accumulation capacitor in the pixel, converting the voltage, and amplifying the signal in the amplifier transistor TA to read the signal, the sensor signal sensitivity (voltage) (Exposure time) / (current accumulation capacity).

Therefore, to increase the sensor signal sensitivity, it is conceivable to increase the photocurrent, (2) increase the exposure time, and (3) reduce the current accumulation capacity.

Particularly, when the parasitic capacitance of the device is used as the current storage capacity, the sensor signal sensitivity voltage can be improved by reducing the parasitic capacitance by the device structure.

(Example of Layout of Thin Film Photodiode)

(P ⁺ region) 36A in the direction perpendicular to the direction of connection to the anode region (N ⁺ region) 36K and the width Wp of the anode region (P ⁺ region) The width Wn of the cathode region (N ⁺ region) 36K in the in-plane direction is different.

The above-described configuration is a configuration in which the area of the overlapping region of the anode region (P ⁺ region) 36A and the control gate 38 when viewed from one side or the other side is defined as the cathode region (N ⁺ region) And the area of the overlapping area of the control gate 38 can be made different.

Specifically, the parasitic capacitance between the anode region (P ⁺ region) 36A or the cathode region (N ⁺ region) 36K where the width is narrowed and the area of the overlapping region with the control gate 38 is reduced, The capacity can be reduced.

Here, when considering the above-described overlapping region, the low concentration semiconductor region (N-region) 36N can be a part of the cathode region 36K.

The case where the occupation area of the low concentration semiconductor region (N-region) 36N is very small and the case where the concentration of the N-type impurity is extremely low can be considered as an exception. The same applies to the following.

In this embodiment, for example, the control gate 38 is connected to the cathode region (N ⁺ region) 36K. Here, a cathode region (N ⁺ region) anode region (P ⁺ region) in a direction perpendicular to a direction for connecting the (36K) connected to the width Wp of (36A), the anode region (P ⁺ region) (36A) (N ⁺ region) 36K in a direction perpendicular to the direction in which the cathode region (N ⁺ region) 36K is formed.

The area of the overlapping region of the anode region (P ⁺ region) 36A and the control gate 38 as viewed from the one surface side or the other surface side is made to be the same as the cathode region (N ⁺ region) 36K And the area of the overlapping area of the control gate 38 can be made smaller. Thus, the parasitic capacitance Cgp between the control gate 38 and the anode region (P ⁺ region) 36A can be reduced.

Particularly, in the thin film photodiode PD, it is preferable that the ratio R1 of the width Wp of the anode region (P ⁺ region) 36A / the width Wn of the cathode region (N ⁺ region) 36K be in a range of 0.3? Do.

The reason why it is preferable to set the above-mentioned range will be described in the following embodiments.

Alternatively, when the control gate 38 is connected to the anode region (P ⁺ region) 36A different from the illustrated photodiode, the following structure is employed. That is, the cathode region (N ⁺ region) is the direction to be connected to (36K), the width Wp of the anode region (P ⁺ region) (36A) in a direction perpendicular, to be connected to the anode region (P ⁺ region) (36A) (N ⁺ region) 36K in the direction perpendicular to the direction of the gate electrode 36K.

The area of the overlapping region of the anode region (P ⁺ region) 36A and the control gate 38 as viewed from the one surface side or the other surface side is made to be the same as the cathode region (N ⁺ region) 36K And the overlapping area of the control gate 38 is larger. Thus, the parasitic capacitance Cgn between the control gate 38 and the cathode region (N ⁺ region) 36K can be reduced as described above.

Particularly, in the thin film photodiode PD, it is preferable that the ratio R2 of the width Wn of the cathode region (N ⁺ region) 36K / the width Wp of the anode region (P ⁺ region) 36A is in a range of 0.3? Do.

The reason why it is preferable to set the above-mentioned range will be described in the following embodiments.

(Connection of the cathode region and the gate electrode)

6A is a circuit diagram showing the parasitic capacitance present in the above-described thin film photodiode and control gate.

The following parasitic capacitances exist in the thin film photodiode and the control gate.

(1) The parasitic capacitance Cgp between the control gate 38 and the anode region (P ⁺ region) 36A

(2) Parasitic capacitance Cgn between the control gate 38 and the cathode region (N ⁺ region) 36K

(3) Parasitic capacitance Cjnc of the junction between the anode region (P ⁺ region) 36A and the cathode region (N ⁺ region) 36K.

As described above, when the control gate 38 is connected to the cathode region (N ⁺ region) 36K, the circuit diagram of FIG. 6A is the structure shown in FIG. 6B.

In other words, the parasitic capacitance Cgn between the control gate 38 and the cathode region (N ⁺ region) 36K is not apparent. Therefore, the above-described current storage capacity, the control gate 38 and the anode region (P ⁺ region) (36A), the parasitic capacitance Cgp and the anode region (P ⁺ region) (36A) and a cathode region (N ⁺ region) between And the parasitic capacitance Cjnc of the junction between the source and drain regions 36K.

On the other hand, the control gate 38, the anode region (P ⁺ region) if it is connected to (36A), a control gate 38 and the anode region (P ⁺ region) (36A) does not apparently exist parasitic capacitance Cgp between . Therefore, the above-described current storage capacity, the control gate 38 and the cathode region (N ⁺ region) (36K), the parasitic capacitance Cgn and the anode region (P ⁺ region) (36A) and a cathode region (N ⁺ region) between And the parasitic capacitance Cjnc of the junction between the source and drain regions 36K.

The control gate 38 is connected to the cathode region (N ⁺ region) 36K or the anode region (P ⁺ region) 36A as described above, whereby the parasitic capacitance Cgn or the parasitic capacitance Cgp is apparent I never do that. Thus, by reducing the parasitic capacitance, the sensor signal sensitivity voltage can be improved.

As described above, the parasitic capacitance formed between the control gate 38 of the anode region (P ⁺ region) 36A and the cathode region (N ⁺ region) 36K, that is, the parasitic capacitances Cgp and Cgn It is preferable that the control gate 38 is connected. It is possible to increase the effect of reducing the parasitic capacitance by setting the larger capacitance of the parasitic capacitances Cgp and Cgn to be absent.

The above-described thin film photodiode PD includes parasitic elements formed by the p-type semiconductor regions (anode region (P ⁺ region) 36A and metal film (control gate 38)) opposed to each other via an insulating film (gate insulating film 50) Capacity Cgp.

(Parasitic capacitance Cgn constituted by the N-type semiconductor region (cathode region (N ⁺ region) 36K and the metal film (control gate 38) opposed to each other through the gate insulating film 50).

In this embodiment, the area of the overlapping region of the anode region (P ⁺ region) 36A and the control gate 38 as seen from one side or the other side is larger than the area of the cathode region (N ⁺ region) 36K And the area of the overlapping region of the control gate 38 are different from each other. Thus, the capacitance value of the parasitic capacitance Cgp is different from the capacitance value of the parasitic capacitance Cgn.

As a result, the parasitic capacitance is reduced compared to the conventional thin film photodiode, that is, the current storage capacity is reduced.

The parasitic capacitance formed between the opposing control gates 38 of the anode region (P ⁺ region) 36A and the cathode region (N ⁺ region) 36K through the gate insulating film 50, The control gate 38 is connected to the largest one of the capacitances Cgp and Cgn.

The parasitic capacitances of the parasitic capacitances Cgp and Cgn, which are large in capacitance, can be made to appear to be absent, so that the parasitic capacitance can be further reduced, that is, the current storage capacity can be further reduced.

According to the liquid crystal display device having the photosensor portion having the thin film photodiode according to the present embodiment, the sensitivity of the sensor signal can be increased by reducing the current accumulation capacitance, which is the parasitic capacitance, as described above.

In the above-described configuration, when the width Wp of the anode region (P ⁺ region) 36A fluctuates, the sensitivity may be affected.

(Improvement of sensor sensitivity and improvement of saturation characteristics)

However, when the sensitivity of the photosensor portion is increased by reducing the parasitic capacitance of the thin film photodiode as described above, the saturation characteristics of the sensor are affected.

In this embodiment, as described below, the light component incident on the thin film photodiode PD is precisely irradiated, and the light to be detected is incident on the thin film photodiode as much as possible from the operation of the thin film photodiode, And improvement of the saturation characteristics are both achieved.

The thin film photodiode PD having sensitivity to the invisible light described above is a thin film photodiode PD having sensitivity to S (t) by "stray light" leading to the thin film photodiode PD due to repeated reflection in the liquid crystal panel 200 without reaching the object to be detected / N ratio is likely to decrease.

For example, the light incident on the thin film photodiode is similarly distinguished as follows: (1) light noise reflected from the deflection plate air interface and entering the thin film photodiode; (2) light noise that enters the thin film photodiode after the backlight is reflected by the metal wiring, (3) light noise that the backlight enters the thin film photodiode directly; And (4) the optical signal in which the backlight is reflected from the user's finger.

As described above, when non-visible light from the backlight is reflected by the wirings such as the VDD line 31, the VSS line 32, the detection line 35 and the like and the electrodes such as the control gate 38, The amount of light reaching the front side decreases. In addition, before reaching the front surface side of the panel, the light is returned to the thin film photodiode PD side as stray light, and is received as noise components by the thin film photodiode PD.

Considering the operation of the thin film photodiode, when the control gate 38 is connected to the cathode region (N ⁺ region) 36K, the anode region (P ⁺ region) 36A and the I- A depletion layer is formed in the vicinity of the boundary, so that the photosensitivity in the region is increased.

Therefore, preventing the stray light from the backlight from entering the I-region 36I suppresses the incidence of the stray light into the high-sensitivity portion of the thin-film photodiode PD and improves the S / N ratio to improve the dynamic range .

The control gate 38 provided in the thin film photodiode of this embodiment is a metal film, and it is possible to prevent stray light from entering from the backlight side.

More specifically, the layout of the control gate 38 below the portion with high light sensitivity of the thin film photodiode PD can suppress the incidence of stray light.

In particular, the anode region (P ⁺ region) (36A) cathode region (N ⁺ region) (36K) side of the distance D of the end of the end portion and the control gate 38, the anode region (P ⁺ region) (36A) on the side of the , And preferably in the range of 1.5 mu m to 3.0 mu m.

In addition, a cathode region (N ⁺ region) anode region (P ⁺ region) (36A) side of the distance of the end of the end portion and controls the cathode region (N ⁺ region) of the gate (38) (36K) side of the (36K), It is preferably in the range of 1.5 탆 to 3.0 탆.

The reason why it is preferable to set the above-mentioned range will be described in the following embodiments.

(action)

Next, an example of a schematic operation of the liquid crystal display device 100 will be described.

In the pixel region, a backlight 300 is provided on the rear side of the liquid crystal panel 200. [ The illumination light from the backlight 300 is incident on the first polarizing plate 206, the TFT array substrate 201, the liquid crystal layer 203, the color filter 204, the color filter substrate 202 and the second polarizing plate 207 And exits from the front surface for screen display.

During the transmission process, the transmitted light is polarized in the first direction when the first polarizing plate 206 is transmitted. The polarization direction of the transmitted light changes by a predetermined angle along the molecular alignment direction of the liquid crystal due to the effect of the optical anisotropy of the liquid crystal molecules while the light is transmitted through the liquid crystal layer 203. When the second polarizing plate 207 is transmitted, the transmitted light is polarized in the second direction deviating from the first direction by a predetermined angle.

During the three polarizing operations, the polarization angle during transmission through the liquid crystal layer 203 changes independently for each pixel by controlling the electric field intensity applied to the liquid crystal layer 203 in accordance with the potential of the input video signal. Therefore, the light passing through each pixel is emitted from the liquid crystal panel 200 after undergoing modulation that changes in brightness according to the potential of the video signal, and realizes a predetermined image display.

On the other hand, light passing through the photosensor section in the sensor region is emitted from the liquid crystal panel 200 as it is without modulating due to the electric signal, unlike the light transmitted through the pixels.

In the middle of image display, for example, there is a case in which a user instruction is urged to display content according to an application. In such a case, the user lightly touches the display screen with a finger or a stylus pen.

The light emitted from the liquid crystal panel 200 is reflected by the object to be detected and returned to the liquid crystal panel 200 when the object to be detected such as a user's finger or a stylus pen touches or approaches the display screen. Since the returned light (reflected light) repeats refraction and reflection at the layer interface in the liquid crystal panel 200 and the reflection object such as wiring, the reflected light propagates to the liquid crystal panel 200 and proceeds in general. Therefore, the reflected light reaches at least one of the plurality of photosensor portions 1, depending on the size of the object to be detected.

When part of the reflected light is incident on the thin film photodiode PD to which the predetermined reverse bias is applied, the thin film photodiode PD performs photoelectric conversion to generate photo charges. (P ⁺ region) 36A or the like which is photoelectrically stored in the storage node SN, which is a current storage capacitor, and outputs it through the amplifier transistor TA connected thereto. The amount of charge at this time represents light receiving data proportional to the amount of received light. The light reception data (charge amount) is output from the detection line 35 of the reading circuit shown in Fig. 3B as the detection potential Vdet or the detection current Idet.

The detection potential Vdet or the detection current Idet is sent to the sensor driver 13 side by the switch array (SEL.SW.) 14 shown in FIG. 2 and is collected as light reception data here, Is input to the position detection unit 402 in the control unit 400. The position detection unit 402 or the control unit 401 inputs a set of the row and column addresses for each detection potential Vdet or detection current Idet in order from the liquid crystal panel 200 side in real time. Therefore, in the data processing unit 400, position information (detection potential Vdet or detection current Idet) in the panel of the object to be detected is stored in the memory in association with the address information in the row and column directions in a memory (not shown).

The liquid crystal display device 100 can determine that the user has performed the instruction based on the display information by using a finger or a stylus pen or the like by superimposing the position information of the object to be detected and the display information according to the information in the memory . Alternatively, it can be determined that "the user has input predetermined information by moving the stylus pen or the like on the display screen ". Thus, the liquid crystal display device 100 can realize the same function as that in the case of adding the touch panel to the liquid crystal panel 200 by a thin display panel which does not include a touch panel. Such a display panel is referred to as an " in-cell touch panel ".

(Method of forming thin film photodiode)

Next, a method of forming a thin film photodiode provided in the photosensor unit of the liquid crystal display device according to the present embodiment will be described.

FIG. 7A is a plan view showing a step of forming a thin film photodiode forming method, and FIG. 7B is a sectional view taken along the line X-X 'in FIG. 7A.

For example, a metal film such as molybdenum is formed on the TFT array substrate 201 by a sputtering method or the like, and patterned into a pattern of a control gate to form a control gate 38. [

Next, the gate insulating film 50 is formed by laminating silicon nitride and silicon oxide by, for example, a chemical vapor deposition (CVD) method or the like.

Next, for example, a semiconductor such as polysilicon is deposited by a CVD method or the like, and patterned in the form of a thin film photodiode to form the semiconductor layer 36. [ The semiconductor layer 36 is made of a semiconductor which becomes an intrinsic semiconductor region of the PIN diode without implanting conductive impurities.

FIG. 8A is a plan view showing a step subsequent to the steps shown in FIGS. 7A and 7B, and FIG. 8B is a cross-sectional view taken along line X-X 'in FIG. 8A.

Next, a photoresist film is formed on the entire upper surface of the semiconductor layer 36 by, for example, coating. Next, light is applied to the entire surface from one side (back surface) side of the TFT array substrate 201, the photoresist film is exposed using the control gate 38 as a mask, and a pattern A resist mask M1 of a thickness of 1 mu m is formed.

By the exposure using the control gate 38 as a mask, the resist mask M1 can be patterned in a self-aligning manner with respect to the control gate 38. [

FIG. 9A is a plan view showing a step subsequent to the steps shown in FIGS. 8A and 8B, and FIG. 9B is a cross-sectional view taken along line X-X 'in FIG. 9A.

Next, for example, an N-type conductive impurity is ion-implanted at a low concentration using the resist mask M1 as a mask to form a low-concentration semiconductor region 36N containing N-type conductive impurities at a low concentration.

At this time, the portion protected by the resist mask M1 becomes the I-region (intrinsic semiconductor region) 36I.

FIG. 10A is a plan view showing a step subsequent to the steps shown in FIGS. 9A and 9B, and FIG. 10B is a cross-sectional view taken along line XX 'in FIG. 10A.

Next, for example, a resist mask M2 having a pattern opening the region to be the anode region (P ⁺ region) 36A is patterned by a photolithography process while leaving the resist mask M1 described above. Here, the resist mask M2 is a pattern in which the resist mask M1 partially overlaps with the resist mask M1, and the resist mask M1 and the resist mask M2 are aligned to form a pattern for protecting portions other than the anode region (P ⁺ region) 36A.

Then, using the resist mask M1 and the resist mask M2 as a mask, for example, a P-type conductive impurity is ion-implanted into the exposed portion of the low-concentration semiconductor region 36N at a high concentration to form a P-type conductive impurity An anode region (P ⁺ region) 36A is formed.

The position of the end of the anode region (P ⁺ region) 36A can be determined by the resist mask M1 and therefore the anode region (P ⁺ region) 36A is formed in a self-aligning manner with respect to the control gate 38 do.

11A is a plan view showing a step subsequent to the steps shown in FIGS. 10A and 11B, and FIG. 11B is a cross-sectional view taken along line XX 'in FIG. 11A.

Next, for example, the resist mask M 1 and the resist mask M 2 are peeled off and a resist mask M 3 having a pattern that opens a region to be a cathode region (N ⁺ region) 36 K is formed by a photolithography process.

Here, the low concentration semiconductor region 36N is formed so as to have a predetermined width so that the low concentration semiconductor region 36N is left between the cathode region (N ⁺ region) 36K and the I-region 36I.

Next, using the resist mask M3 as a mask, for example, an N-type conductive impurity is ion-implanted into the exposed portion of the low-concentration semiconductor region 36N at a high concentration to form a negative electrode region 36 containing a high concentration of N-type conductive impurities (N ⁺ region) 36K.

As a subsequent step, for example, the resist mask M3 is peeled off. Next, the anode region (P ⁺ region) (36A), I- domain (an intrinsic semiconductor region) (36I), a semiconductor layer (36, including low-concentration semiconductor region (36N) and a cathode region (N ⁺ region) (36K) The first interlayer insulating film 51 is formed on the entire upper surface of the first interlayer insulating film 51 by CVD or the like. Next, contact holes respectively reaching the anode region (P ⁺ region) 36A and the cathode region (N ⁺ region) 36K are opened, and a conductive layer is buried in the contact holes to form the contact plugs 54 .

As described above, the thin film photodiodes included in the photosensor portion of the liquid crystal display device according to the present embodiment as shown in Figs. 5A and 5B can be formed.

<Modifications>

12A is a plan view of a thin-film photodiode PD having a PIN structure, and FIG. 12B is a cross-sectional view taken along line XX 'in FIG. 12A.

And is substantially equivalent to the structure shown in Figs. 5A and 5B. The width Wp of the cathode region (N ⁺ region) anode region (P ⁺ region) in a direction perpendicular to a direction for connecting the (36K) (36A), the direction to be connected to the anode region (P ⁺ region) (36A) Is narrower than the width Wn of the cathode region (N ⁺ region) 36K in the vertical direction. Anode region (P ⁺ region) (36A) cathode region (N ⁺ region) (36K) in the vicinity of the end side, a cathode region (N ⁺ region) of the width (36K) Wn (or I- region (intrinsic semiconductor region (P ⁺ region) portion 36AW having a width equal to the width of the anode region (P ⁺ region) 36I).

To suppress the anode region (P ⁺ region) anode area due to narrowing the width Wp of (36A) (P ⁺ region) (36A) and a cathode region (N ⁺ region), the photocurrent flowing between (36K) is smaller . Further, it is possible to suppress the decrease in the effect of increase in sensitivity due to narrowing the width Wp of the anode region (P ⁺ region) 36A.

Further, there is an advantage that the effect of the matching of the interface positions or the shift of the alignment in the manufacturing process is smaller than that of Figs. 5A and 5B.

<Example 1>

As a thin film photodiode shown in Figs. 5A and 5B, a thin film photodiode according to a conventional example in which the width Wp of the anode region (P ⁺ region) 36A and the width Wn of the cathode region (N ⁺ region) Diodes were fabricated.

Here, the anode region (P ⁺ region) (36A), the width Wp anode region (P ⁺ region) (36A) and a cathode region (N ⁺ region) by separation of the (36K), the control gate of the gate capacitance Cg seen from the gate terminal of the The dependence of the applied voltage Vg was examined. Here, the width of the I-region 36I arranged to be sandwiched between the anode region (P ⁺ region) 36A and the cathode region (N ⁺ region) 36K is 4.5 .mu.m (a) , 6.5 μm (c), 7.5 μm (d), 8.5 μm (e), and 9.5 μm (f). In this case, the overlap of the control gate-cathode region (N ⁺ region) 36K and the overlap of the control gate-anode region (P ⁺ region) 36A is not changed.

The above-described results are shown in Fig.

When a predetermined amount of voltage is applied to the control gate, the larger the width of the I-region 36I, the larger the gate capacitance Cg. However, when the voltage of the control gate is 0V, The gate capacitance Cg was constant (about 150 fF).

14 shows the results of (a) the value of the gate capacitance Cg at the time of application of the gate voltage of 10 V and (b) the value of the gate capacitance Cg at the time of application of the gate voltage of 0 V, Plotted against width L.

When the gate voltage is 10V, the larger the width of the I-region 36I, the larger the gate capacitance Cg.

When the gate voltage is 0V, the gate capacitance Cg is constant (approximately 150fF) regardless of the width of the I-region 36I.

In the above-mentioned result, the gate capacitance increases as the width of the I-region 36I increases, which corresponds to the channel capacitance. On the other hand, I- domain (36I) in the width becomes constant Cg is the gate capacitance, the control gate, regardless of-the anode region (P ⁺ region) (36A), - a cathode region (N ⁺ region) overlapping with the control gate of the (36K) The parasitic capacitance is determined by the overlapping.

<Example 2>

In the thin film photodiodes shown in Figs. 5A and 5B, the width Wn of the anode region (N ⁺ region) 36K is set to 100 mu m and the width Wp of the anode region (P ⁺ region) And a change in the parasitic capacitance Cp was measured.

The results are shown in Fig. In the figure, a is the parasitic capacitance seen from the control gate 38, and b is the parasitic capacitance seen from the anode region (P + region) 36A.

As can be seen from the figure, the anode region (P ⁺ region) 36A when the parasitic capacitance element, the control gate 38 and the cathode region (N ⁺ region) 36K are connected from the control gate 38, The parasitic capacitance component seen from the anode region (P ⁺ region) 36A decreases together with the decrease in the width of the anode region (P ⁺ region) 36A. Therefore, in order to reduce the parasitic capacitance, reduction of the amount of overlap between the control gate 38-anode region (P ⁺ region) 36A and the control gate 38-cathode region (N ⁺ region) 36K is effective .

In this case, since the sensor signal sensitivity (voltage) is expressed by (photocurrent) x (exposure time) / (current storage capacity) as described above, if reduction of capacitance can be realized by keeping the photocurrent constant, It becomes possible.

<Example 3>

5A and 5B, the width Wn of the anode region (N ⁺ region) 36K is set to 100 mu m and the width Wp (P ⁺ region) 36A of the anode region A thin film photodiode was prepared. The change in photocurrent Inp of the thus obtained thin film photodiode was measured.

The results are shown in Fig. Photocurrent Inp the anode region (P ⁺ region) if that is proportional to the width Wp of (36A), data will be plotted on the dotted line passing through the origin in the drawing, but actually, the anode region (P ⁺ region) width (36A) It is found that even if Wp is narrowed, a photocurrent flows larger than in the case of proportional.

Specifically, when one of the width Wn of the cathode region (N ⁺ region) 36K and the width Wp of the anode region (P ⁺ region) 36A is narrowed, the photocurrent does not exhibit an extreme decrease even though the photocurrent is not kept constant . Therefore, it is shown that narrowing the width Wn of the cathode region (N ⁺ region) 36K or the width Wp of the anode region (P ⁺ region) 36A can contribute to the improvement of the sensitivity.

<Example 4>

As described above, the sensor signal sensitivity (voltage) can be expressed by (photocurrent) x (exposure time) / (current accumulation capacity). Thus, in a thin film photodiode in which the width Wn of the cathode region (N ⁺ region) 36K is 100 mu m and the width Wp of the anode region (P ⁺ region) 36A is varied in various ways, The relative sensitivity RS (relative value) of the thin film photodiode was estimated.

The results are shown in Fig. When the width Wp of the anode region (P ⁺ region) 36A is narrowed, the relative sensitivity significantly increases.

However, if the width Wp of the anode region (P ⁺ region) 36A becomes smaller, there is a problem that the sensitivity changes greatly depending on the width Wp of the actually formed anode region (P ⁺ region) 36A.

(P ⁺ region) 36A (region) is formed with respect to the width Wn (100 mu m) of the cathode region (N ⁺ region) 36K as the region where the sensitivity of the sensor is increased and the non- ) Is preferably not less than 30 占 퐉 and less than 100 占 퐉.

In other words, in the thin film photodiode PD, the ratio R1 of the width Wp of the anode region (P ⁺ region) 36A / the width Wn of the cathode region (N ⁺ region) 36K is in the range of 0.3? R1 < .

<Example 5>

Anode region (P ⁺ region) (36A) cathode region (N ⁺ region) (36K), the anode region of the end portion and the control gate 38 of the side (P ⁺ region) (36A), a number of the distance D of the end portion of the side of the To the thin film photodiode. Here, a relative light amount RL (relative value) corresponding to a noise component, in which light from the backlight is reflected on a wiring or the like and is incident on the thin film photodiode, is obtained by simulation.

The results are shown in Fig. As the distance D increases, the relative light quantity RL becomes smaller.

Here, actual optical signal level SIG is shown in the figure. By setting the distance D to 0.5 mu m or more, it has been found that the optical signal level is larger than the noise component.

<Example 6>

In the thin film photodiodes shown in Figs. 5A and 5B, the width Wn of the cathode region (N ⁺ region) 36K is set to 100 mu m and the width Wp of the anode region (P ⁺ region) 36A is set to 30 mu m , The following estimates were made.

Here, the anode region (P ⁺ region) (36A) cathode region (N ⁺ region) (36K) side of the end portion and the control gate 38, the anode region (P ⁺ region) (36A), the distance D of the end portion of the side of the I changed it in various ways. In the above-described thin film photodiode, the relative sensitivity RS (relative value) of the thin film photodiode was estimated by keeping the exposure time constant.

The results are shown in Fig. As the distance D increases, the relative sensitivity RS becomes smaller.

As can be seen from the figure, the end of the anode region (P ⁺ region) 36A on the cathode region (N ⁺ region) 36K side and the anode region (P ⁺ region) 36A side It is preferable to set the distance D of the end portion of the light-shielding film to a range of 1.5 mu m to 3.0 mu m. Thus, the sensor sensitivity and the stability of the non-uniformity can be realized.

<Example 7>

In the thin film photodiodes shown in Figs. 5A and 5B, the width Wn of the cathode region (N ⁺ region) 36K is set to 100 mu m and the width Wp of the anode region (P ⁺ region) 36A is set to 30 mu m , The following estimates were made.

Here, the anode region (P ⁺ region) (36A) cathode region (N ⁺ region) (36K) side of the end portion and the control gate 38, the anode region (P ⁺ region) (36A), the distance D of the end portion of the side of the I changed it in various ways. In the above-described thin film photodiode, the light amount LSAT (relative value) saturating the signal of the photosensor portion was estimated.

The results are shown in Fig. Anode region (P ⁺ region) (36A) cathode region (N ⁺ region) (36K), the anode region of the end portion and the control gate 38 of the side (P ⁺ region) (36A) 1.5μm the distance D of the end portion of the side of the To 3.0 mu m.

As a result, it was found that the saturation characteristic was improved to 2.5 times as compared with the case of D = -0.2 占 퐉.

As a result, it was found that the dynamic range was improved in addition to the sensitivity characteristic of the sensor.

According to the present embodiment and its modifications, the width of the P-type semiconductor region and the width of the N-type semiconductor region in the thin film photodiode formed in the sensor region of the display section (substrate) are made different. As a result, the parasitic capacitance between the thin film photodiode and the metal film can be reduced to improve the detection sensitivity of the sensor and improve the saturation characteristics of the sensor.

&Lt; Embodiment 2 &gt;

21A is a plan view of the thin film photodiode PD having the PIN structure in this embodiment, and FIG. 21B is a sectional view taken along line XX 'in FIG. 21A. In Fig. 21B, the wiring of the VDD line 31 and the like and the structure of the upper layer than the second interlayer insulating film 52 are omitted. Except for the configuration of the thin film photodiode PD, the display device of this embodiment has the same configuration as that of the first embodiment.

For example, a control gate 38 made of a "metal film " is formed on the TFT array substrate 201, a two-layer gate insulating film 50 is formed on the control gate 38, Respectively.

The semiconductor layer 26 has a pattern shape shown in Fig. 21A. Specifically, P ⁺ regions formed in the anode region (P-type semiconductor region) (36A), I- domain (an intrinsic semiconductor region) (36I), the low-concentration semiconductor region of the low concentration semiconductor region (N- region) (36N), N ⁺ And a cathode region 36K made of a region (N-type semiconductor region) are laid out. Thus, a thin film photodiode having a PIN structure having a low concentration semiconductor region is formed.

In this layout, the cathode region (N ⁺ region) connected to the width Wp and the anode region (P ⁺ region) (36A) of the anode region (P ⁺ region) in a direction perpendicular (36A) in the direction to be connected to (36K) And the width Wn of the cathode region (N ⁺ region) 36K in the direction perpendicular to the direction in which the cathode region (Y) is formed.

The layout of the control gate 38 for each of the above-described regions is as shown in Fig. 21A.

The anode region (P ⁺ region) 36A is formed outside the overlap region with the control gate 38 and extends in the direction perpendicular to the direction of connection to the cathode region (N ⁺ region) (36AL) is provided.

The first interlayer insulating film 51 is formed so as to cover the photodiode described above and is electrically connected to the contact hole CT through the contact hole CT reaching the anode region (P ⁺ region) 36A and the cathode region (N ⁺ region) And is connected to the plug 54. The contact hole reaching the anode region (P ⁺ region) 36A is provided in the above extending portion 36AL.

In this embodiment, the area of the overlapping region of the anode region (P ⁺ region) 36A and the control gate 38 as seen from one side or the other side is larger than the area of the cathode region (N ⁺ region) 36K And the area of the overlapping region of the control gate 38 are different from each other. Thus, the capacitance value of the parasitic capacitance Cgp is different from the capacitance value of the parasitic capacitance Cgn.

As a result, the parasitic capacitance is reduced compared with the conventional thin film photodiode, that is, the current storage capacity is reduced.

The parasitic capacitance formed between the opposing control gates 38 of the anode region (P ⁺ region) 36A and the cathode region (N ⁺ region) 36K through the gate insulating film 50, It is preferable that the control gate 38 is connected because the capacitance values of the capacitances Cgp and Cgn are large. In the present embodiment, the control gate 38 is connected to the cathode region (N ⁺ region) 36K.

The parasitic capacitance having a larger capacitance than the parasitic capacitances Cgp and Cgn can be made non-existent so that the parasitic capacitance can be further reduced, that is, the current storage capacitance can be further reduced.

According to the liquid crystal display device having the photosensor portion having the thin film photodiode according to the present embodiment, the sensitivity of the sensor signal can be increased by reducing the current accumulation capacitance, which is the parasitic capacitance, as described above.

In the thin film photodiode of the present embodiment, the structure of the anode region (P ⁺ region) 36A outside the overlapping region with the control gate 38 is basically arbitrary.

On the other hand, it is preferable that the extending portion 36AL is not provided or shortened as short as possible for the following reason. However, the present invention can be applied to a case where the opening area of the contact hole is limited.

<Example 8>

A thin film photodiode of the display device according to the first embodiment and a thin film photodiode of the display device according to the second embodiment were manufactured. Here, the width Wn of the anode region (N ⁺ region) 36K was set to 100 mu m and the width Wp of the anode region (P ⁺ region) 36A was varied in various ways. In such a thin film photodiode, a change in parasitic capacitance having a width Wp was measured.

The results are shown in Fig. In the figure, a indicates the parasitic capacitance seen from the anode region (P ⁺ region) 36A in the thin film photodiode of the first embodiment, and b indicates the parasitic capacitance from the anode region P ⁺ region) 36A.

Although the size of the thin film photodiode of the configuration of the first embodiment is large enough to reduce the parasitic capacitance when the width Wp of the anode region (P ⁺ region) 36A is narrowed, the sensor signal In order to increase the sensitivity, the configuration of the first embodiment is preferable.

&Lt; Third Embodiment &gt;

23A is a plan view of the thin film photodiode PD having the PIN structure in this embodiment, and FIG. 23B is a sectional view taken along line XX 'in FIG. 23A. 23B, the wiring of the VDD line 31 and the like and the structure of the upper layer than the second interlayer insulating film 52 are omitted. Except for the configuration of the thin film photodiode PD, the display device of this embodiment has the same configuration as that of the first embodiment.

For example, a control gate 38 made of a "metal film " is formed on the TFT array substrate 201, a two-layer gate insulating film 50 is formed on the control gate 38, Respectively.

The semiconductor layer 26 has a pattern shape shown in Fig. 23A. Specifically, P ⁺ regions formed in the anode region (P-type semiconductor region) (36A), I- domain (an intrinsic semiconductor region) (36I), the low-concentration semiconductor region of the low concentration semiconductor region (N- region) (36N), N ⁺ And a cathode region 36K made of a region (N-type semiconductor region) are laid out. Thus, a thin film photodiode having a PIN structure having a low concentration semiconductor region is formed.

In this layout, the cathode region (N ⁺ region) connected to the width Wp and the anode region (P ⁺ region) (36A) of the anode region (P ⁺ region) in a direction perpendicular (36A) in the direction to be connected to (36K) And the width Wn of the cathode region (N ⁺ region) 36K in the direction perpendicular to the direction in which the cathode region (Y) is formed.

The layout of the control gate 38 for each of the above-described regions is as shown in Fig. 21A.

The first interlayer insulating film 51 is formed so as to cover the photodiode described above and is electrically connected to the contact hole CT through the contact hole CT reaching the anode region (P ⁺ region) 36A and the cathode region (N ⁺ region) And is connected to the plug 54.

Here, in the edge vicinity of the I- domain (36I) the anode region (P ⁺ region) (36A) on the side of the anode region (P ⁺ region) I- area portion having the same width as the width Wp of (36A) (36IW ).

In this embodiment, the area of the overlapping region of the anode region (P ⁺ region) 36A and the control gate 38 as seen from one surface side or the other surface side is larger than the area of the cathode region N ⁺ region) 36K and the control gate 38. In this case, Thus, the capacitance value of the parasitic capacitance Cgp is different from the capacitance value of the parasitic capacitance Cgn.

As a result, the parasitic capacitance is reduced compared with the conventional thin film photodiode, that is, the current storage capacity is reduced.

The capacitance value of the parasitic capacitance formed between the opposing control gates 38 of the anode region (P ⁺ region) 36A and the cathode region (N ⁺ region) 36K through the gate insulating film 50 is large It is preferable that the control gate 38 is connected. In other words, it is preferable that the control gate 38 is connected to the gate of the transistor having a large capacitance value of the parasitic capacitances Cgp and Cgn. In the present embodiment, the control gate 38 is connected to the cathode region (N ⁺ region) 36K.

The parasitic capacitance of the parasitic capacitances Cgp and Cgn, which are large in the appearance, can be made non-existent so that the parasitic capacitance can be further reduced, that is, the current storage capacity can be further reduced.

According to the liquid crystal display device having the photosensor portion having the thin film photodiode according to the present embodiment, the sensitivity of the sensor signal can be increased by reducing the current accumulation capacitance, which is the parasitic capacitance, as described above.

Actually, in the thin film photodiode according to the present embodiment, since the area of the overlapping region of the anode region (P ⁺ region) 36A and the control gate 38 can be made narrower than that of the thin film photodiodes of the first embodiment, the parasitic capacitance Cgp Which is lower than that of the first embodiment.

In addition, since the interface between the I-region 36I and the anode region (P ⁺ region) 36A is formed at the portion of the width Wp, the influence of the matching of the interfacial position or the shift of the alignment in the manufacturing process .

In the above-described configuration, when the width Wp of the anode region (P ⁺ region) 36A fluctuates, the sensitivity may be affected.

Further, since the region of width Wp is formed in the I-region 36I, there is a possibility that the loss due to the recombination is larger than that of the first embodiment. When the loss is large, it is important to reduce the area of the I-region portion 36IW and examine it in a range with a small influence.

<Fourth Embodiment>

24A is a plan view of the thin film photodiode PD having the PIN structure in this embodiment, and FIG. 24B is a sectional view taken along line XX 'in FIG. 24A. 24B, the wiring of the VDD line 31 and the like and the structure of the upper layer than the second interlayer insulating film 52 are omitted. Except for the configuration of the thin film photodiode PD, the display device of this embodiment has the same configuration as that of the first embodiment.

For example, a control gate 38 made of a "metal film " is formed on the TFT array substrate 201, a two-layer gate insulating film 50 is formed on the control gate 38, Respectively.

The semiconductor layer 36 has a pattern shape shown in Fig. 24A. Specifically, P ⁺ regions formed in the anode region (P-type semiconductor region) (36A), I- domain (an intrinsic semiconductor region) (36I), the low-concentration semiconductor region of the low concentration semiconductor region (N- region) (36N), N ⁺ And a cathode region 36K made of a region (N-type semiconductor region) are laid out. Thus, a thin film photodiode having a PIN structure having a low concentration semiconductor region is formed.

The first interlayer insulating film 51 is formed so as to cover the photodiode described above and is electrically connected to the contact hole CT through the contact hole CT reaching the anode region (P ⁺ region) 36A and the cathode region (N ⁺ region) And is connected to the plug 54.

The overlap width Lp of the anode region (P ⁺ region) 36A and the control gate 38 as seen from one surface side or the other surface side is larger than the overlap width Lp between the cathode region (N ⁺ region) Is narrower than the overlapping width Ln of the overlapping portion 38. [

This, first as in the embodiment, the one surface side or the anode region when viewed from the other surface side (P ⁺ region) (36A) and control the area of the overlapping area of the gate 38, the cathode region (N ⁺ region (36K) and the control gate 38. In this case, Thus, the capacitance value of the parasitic capacitance Cgp is different from the capacitance value of the parasitic capacitance Cgn.

As a result, the parasitic capacitance is reduced compared with the conventional thin film photodiode, that is, the current storage capacity is reduced.

The parasitic capacitance formed between the control gate 38 opposed to the anode region (P ⁺ region) 36A and the cathode region (N ⁺ region) 36K through the gate insulating film 50 is connected to the control gate 38 ) Are preferably connected. In summary, it is preferable that the control gate 38 is connected so that the capacitance values of the above-described parasitic capacitances Cgp and Cgn are large. In the present embodiment, the control gate 38 is connected to the cathode region (N ⁺ region) 36K.

The parasitic capacitance of the parasitic capacitances Cgp and Cgn, which are large in the appearance, can be made non-existent so that the parasitic capacitance can be further reduced, that is, the current storage capacity can be further reduced.

According to the liquid crystal display device having the photosensor portion having the thin film photodiode according to the present embodiment, the sensitivity of the sensor signal can be increased by reducing the current accumulation capacitance, which is the parasitic capacitance, as described above.

Actually, the thin film photodiode according to the present embodiment has an advantage that the loss due to recombination is smaller than that in the first embodiment.

The influence on the sensitivity when the width Wp of the anode region (P ⁺ region) 36A fluctuates also becomes smaller than that in the first embodiment.

In addition, since the interface between the I-region 36I and the anode region (P ⁺ region) 36A is formed at the portion of the width Wp, the influence of the matching of the interface positions in the manufacturing process and the shift of the alignment, .

<Example 9>

In the thin film photodiode of the display device according to the fourth embodiment, in which the width Wn of the cathode region (N ⁺ region) 36K is equal to the width Wp of the anode region (P ⁺ region) 36A, Length) were variously changed to fabricate a thin film photodiode. Here, the overlap width Lp of the anode region (P ⁺ region) 36A and the control gate 38, the overlap width Ln of the control gate 38 and the cathode region (N ⁺ region) 36K are 0.5 μm and 1.5 μm, respectively.

In the above-described thin film photodiode, a control gate 38 and anode region at the time eoteul change the length W- (P ⁺ region) (36A), the parasitic capacitance Cgp, the control gate 38 and the cathode region between the (N ⁺ region ) (36K) of the parasitic capacitance Cgn.

The results are shown in Fig.

As can be seen from the figure, Cgp and Cgn increase as the W length becomes larger, but Cgn becomes larger than Cgp as the slope with respect to the W-length becomes larger and the W length becomes larger.

Here, as shown in the fourth embodiment, by connecting between the control gate 38 and the cathode region (N ⁺ region) 36K, only a smaller parasitic capacitance Cgp is present. Thereby, the parasitic capacitance can be further reduced, and the sensitivity of the sensor signal can be increased by reducing the current storage capacity.

<Fifth Embodiment>

(Application example of display device)

The embodiment and its modifications can be applied as display parts for characters and images of the following various products.

For example, the present invention can be applied to, for example, a television receiver, a monitor device such as a personal computer, a mobile device having a video playback function such as a mobile phone, a game machine, and a PDA, a photographing device such as a still camera or a video camera, Can be applied.

In addition, when infrared rays are used as invisible light, it is possible to detect the distribution of human body temperature as infrared rays. Therefore, the present invention can be applied to effective use of infrared rays in vein authentication of a human finger.

In this case, instead of the liquid crystal panel 200, a vein authentication panel that transmits light from a backlight is provided. The infrared ray is irradiated from the backlight in a state in which a finger of a person is in contact with the surface of the vein authentication panel, And means for performing vein authentication in accordance therewith.

&Lt; First application example &gt;

26 is a perspective view showing a television as a first application example. The television according to the present application example includes a video display screen section 101 composed of a front panel 102, a filter glass 103 and the like, and the above-described display device is applied to the video display screen section 101 .

&Lt; Second application example &

27A and 27B are diagrams showing a digital camera as a second application example, wherein FIG. 27A is a perspective view from the front side, and FIG. 27B is a perspective view from the rear side. The digital camera according to this application example includes a light emitting portion 111 for flash, a display portion 112, a menu switch 113, a shutter button 114, and the like. The display portion 112 is provided with the above- Can be applied.

&Lt; Third application example &gt;

28 is a perspective view showing a notebook type personal computer as a third application example. The notebook type personal computer according to this application example includes a keyboard 122 that is operated when a character or the like is input to the main body 121, a display unit 123 that displays an image, and the like, One display device can be applied.

&Lt; Fourth application example &gt;

29 is a perspective view showing a video camera as a fourth application example. The video camera according to this application example includes a main body 131, a lens 132 for photographing a subject on the side facing forward, a start / stop switch 133 for photographing, a display 134, The above-described display device can be applied to the display device 134.

&Lt; Fifth application example &gt;

30A to 30G are views showing a portable terminal device, for example, a mobile phone, which is a fifth application example. 30B is a front view of the mobile phone in a closed state, Fig. 30D is a left side view, Fig. 30E is a right side view, Fig. 30F is a front view of the mobile phone in a closed state, And Fig. 30G is a bottom view. The mobile phone according to this application example includes an upper housing 141, a lower housing 142, a connection portion (here, a hinge portion) 143, a display 144, a sub display 145, a picture light 146, 147).

The above-described display device can be applied to the display 144 or the sub display 145 described above.

The display device related to this embodiment is not limited to the above description.

For example, in the above-described embodiment, a control gate a cathode region (N ⁺ region) connected to the (36K) side, and the anode region (P ⁺ region) width of the cathode region (N ⁺ region) of (36A) ( 36K). However, the present invention is not limited to this. For example, an embodiment in which the control gate is connected to the anode region (P ⁺ region) 36A side and the width of the cathode region (N ⁺ region) 36K is narrower than the anode region (P ⁺ region) It is possible.

In this case, the ratio R2 of the width Wn of the cathode region (N ⁺ region) 36K / the width Wp of the anode region (P ⁺ region) 36A in the thin film photodiode PD is 0.3 Lt; R2 &lt; 1.

For the same reason as described above, the end portion of the anode region (N ⁺ region) 36K on the anode region (P ⁺ region) 36A side and the cathode region (N ⁺ region) 36K ) Is preferably in the range of 1.5 탆 to 3.0 탆.

Although the liquid crystal display device has been described in the above embodiments, the present invention is not limited thereto, and the present invention may be applied to an organic EL display device or a display device such as an E-paper.

In addition, various modifications are possible without departing from the gist of the present invention.

1 is a schematic overall configuration diagram of a liquid crystal display device according to a first embodiment of the present invention.

2 is a block diagram showing a configuration example of a driving circuit in a liquid crystal display device according to the first embodiment of the present invention.

FIG. 3A is a plan view of an optical sensor unit included in a liquid crystal display according to a first embodiment of the present invention, and FIG. 3B is an equivalent circuit diagram of a photosensor unit corresponding to the pattern of FIG. 3A.

FIG. 4 is a cross-sectional view schematically showing a part of a pixel PIX of a liquid crystal pixel of an FFS (Field Fringe Switching) type optical sensor unit included in the liquid crystal display device according to the first embodiment of the present invention.

5A is a plan view of a photodiode having a PIN structure included in the liquid crystal display according to the first embodiment of the present invention, and FIG. 5B is a cross-sectional view taken along the line X-X 'in FIG. 5A.

6A and 6B are circuit diagrams illustrating parasitic capacitances present in the thin film photodiode and the control gate according to the first embodiment of the present invention.

FIG. 7A is a plan view showing a step of forming a thin film photodiode in a liquid crystal display according to a first embodiment of the present invention, and FIG. 7B is a cross-sectional view taken along the line X-X 'in FIG. 7A.

FIG. 8A is a plan view showing a step subsequent to the steps shown in FIGS. 7A and 7B, and FIG. 8B is a cross-sectional view taken along line X-X 'in FIG. 8A.

FIG. 9A is a plan view showing a step subsequent to the steps shown in FIGS. 8A and 8B, and FIG. 9B is a cross-sectional view taken along line X-X 'in FIG. 9A.

FIG. 10A is a plan view showing a step subsequent to the steps shown in FIGS. 9A and 9B, and FIG. 10B is a cross-sectional view taken along line XX 'in FIG. 10A.

11A is a plan view showing a step subsequent to the steps shown in Figs. 10A and 10B, and Fig. 11B is a sectional view taken along line X-X 'in Fig. 11A.

FIG. 12A is a plan view of a photodiode having a PIN structure provided in a liquid crystal display according to a modification of the embodiment of the present invention, and FIG. 12B is a cross-sectional view taken along line XX 'in FIG. 12A.

FIG. 13 is a graph showing the dependence of the gate capacitance on the applied voltage of the control gate from the gate terminal according to Example 1. FIG.

14 is an explanatory diagram showing the results of FIG. 13 plotted.

15 is a diagram showing the dependency of the parasitic capacitance on the anode region width according to Example 2. Fig.

16 is a view showing the dependency of the photocurrent on the width of the anode region according to Example 3. Fig.

17 is a view showing the dependency of the sensitivity of the anode area on the width of the anode area according to Example 4. Fig.

18 is a diagram showing the distance dependence of the end portion of the anode region and the end portion of the control gate of the relative amount of light corresponding to the noise component according to Example 5. FIG.

19 is a diagram showing the distance dependence of the end portion of the anode region and the end portion of the control gate of the relative sensitivity according to Example 6;

20 is a diagram showing the distance dependence of the end portion of the anode region and the end portion of the control gate in the amount of light saturation of the signal of the photosensor portion according to Example 7;

21A is a plan view of a photodiode having a PIN structure provided in a liquid crystal display device according to a second embodiment of the present invention, and FIG. 21B is a cross-sectional view taken along line XX 'in FIG. 21A.

Figure 22 shows the dependence of the width of the anode region the anode region (P ⁺ region) of the parasitic capacitance from the (P ⁺ region) in accordance with Example 8.

23A is a plan view of a photodiode having a PIN structure included in the liquid crystal display device according to the third embodiment of the present invention, and FIG. 23B is a cross-sectional view taken along line XX 'in FIG.

FIG. 24A is a plan view of a photodiode having a PIN structure included in the liquid crystal display device according to the fourth embodiment of the present invention, and FIG. 24B is a cross-sectional view taken along line XX 'in FIG. 24A.

25 is a graph showing the W-length dependence of the parasitic capacitance according to Example 9;

26 is a perspective view showing a television as a first application example according to the fifth embodiment of the present invention.

27A and 27B are views showing a digital camera as a second application example according to the fifth embodiment of the present invention, wherein FIG. 27A is a perspective view seen from the front side, and FIG. 27B is a perspective view from the back side.

28 is a perspective view showing a notebook-size personal computer as a third application example according to the fifth embodiment of the present invention.

29 is a perspective view showing a video camera according to a fourth application example according to the fifth embodiment of the present invention.

30A to 30E are views showing a cellular phone according to a fifth application example according to the fifth embodiment of the present invention. Fig. 30A is a front view in an open state, Fig. 30B is a side view thereof, Fig. 30D is a left side view, Fig. 30E is a right side view, Fig. 30F is a top view, and Fig. 30G is a bottom view.

Claims (20)

In the display device, A substrate having a pixel region in which pixels are formed and a sensor region in which a photosensor portion is formed; An illumination unit for illuminating the substrate from one side of the substrate; A thin film photodiode disposed in the sensor region and having at least a p-type semiconductor region and an n-type semiconductor region and receiving light incident from the other surface side of the substrate; And Wherein the thin film photodiode is formed to face the thin film photodiode through an insulating film on the one surface side of the substrate so that light generated from the illuminating unit is prevented from directly entering the thin film photodiode from the one surface side, Metal film / RTI &gt; In the thin film photodiode, a width of the P-type semiconductor region in a direction perpendicular to a direction connecting to the N-type semiconductor region and a width of the N-type semiconductor region in a direction perpendicular to a direction connecting to the P- Are formed to have different widths. The method according to claim 1, In the thin film photodiode, an area of the P-type semiconductor region and the overlapping region of the metal film when viewed from the one surface side and the other surface side is different from an area of the overlapping region of the N-type semiconductor region and the metal film , Display device. The method according to claim 1, The metal film is connected to the N-type semiconductor region, In the thin film photodiode, a width of the P-type semiconductor region in a direction perpendicular to a direction connecting to the N-type semiconductor region is larger than a width of the P-type semiconductor region in a direction perpendicular to a direction connecting the P- Is narrower than the width of the display device. The method of claim 3, In the thin film photodiode, the area of the overlapping region of the P-type semiconductor region and the metal film when viewed from the one surface side or the other surface side is smaller than the overlapping region of the N-type semiconductor region and the metal film , Display device. The method of claim 3, In the thin film photodiode, the ratio R1 of the width of the P-type semiconductor region / the width of the N-type semiconductor region is in a range of 0.3? R1 <1. The method according to claim 1, The metal film is connected to the P-type semiconductor region, In the thin film photodiode, a width of the P-type semiconductor region in a direction perpendicular to a direction connecting to the N-type semiconductor region is larger than a width of the P-type semiconductor region in a direction perpendicular to a direction connecting the P- Of the display device. The method according to claim 6, In the thin film photodiode, an area of the p-type semiconductor region and the overlapping region of the metal film when viewed from the one surface side or the other surface side is larger than an area of the overlapping region of the n-type semiconductor region and the metal film , Display device. The method according to claim 6, In the thin film photodiode, the ratio of the width of the N-type semiconductor region / the width of the P-type semiconductor region is in the range of 0.3? R2 <1. The method according to claim 1, Wherein the thin film photodiode has an intrinsic semiconductor region or a lightly doped semiconductor region having a lower conductive impurity concentration than the p-type semiconductor region and the n-type semiconductor region between the n-type semiconductor region and the p- . The method according to claim 1, Wherein the P-type semiconductor region constituting the thin film photodiode and the semiconductor region including the N-type semiconductor region are formed of polycrystalline silicon, microcrystalline silicon, amorphous silicon or crystalline silicon. The method according to claim 1, Wherein the illumination unit emits invisible light, and the thin film photodiode has sensitivity to the invisible light. The method according to claim 1, And a distance between an end of the P-type semiconductor region on the N-type semiconductor region side and an end of the metal film on the P-type semiconductor region side is in a range of 1.5 탆 to 3.0 탆. The method according to claim 1, The distance between the end of the N-type semiconductor region on the P-type semiconductor region side and the end of the metal film on the N-type semiconductor region side is in the range of 1.5 탆 to 3.0 탆. In the display device, A substrate having a pixel region in which pixels are formed and a sensor region in which a photosensor portion is formed; An illumination unit for illuminating the substrate from one side of the substrate; A thin film photodiode disposed in the sensor region and having at least a p-type semiconductor region and an n-type semiconductor region and receiving light incident from the other surface side of the substrate; And Wherein the thin film photodiode is formed to face the thin film photodiode through an insulating film on the one surface side of the substrate so that light generated from the illuminating unit is prevented from directly entering the thin film photodiode from the one surface side, Metal film / RTI &gt; The capacitance value of the parasitic capacitance formed by the P-type semiconductor region and the metal film opposed to each other through the insulating film in the thin film photodiode and the metal film is larger than the capacitance value of the N-type semiconductor region And the capacitance value of the parasitic capacitance constituted by the metal film. In the display device, A substrate having a pixel region in which pixels are formed and a sensor region in which a photosensor portion is formed; An illumination unit for illuminating the substrate from one side of the substrate; A thin film photodiode disposed in the sensor region and having at least a p-type semiconductor region and an n-type semiconductor region and receiving light incident from the other surface side of the substrate; And Wherein the thin film photodiode is formed to face the thin film photodiode through an insulating film on the one surface side of the substrate so that light generated from the illuminating unit is prevented from directly entering the thin film photodiode from the one surface side, Metal film / RTI &gt; Wherein an area of a region where the P-type semiconductor region overlaps with the metal film when viewed from the one surface side or the other surface side in the thin film photodiode is different from an area of the overlapping region of the N-type semiconductor region and the metal film , Display device. 15. The method of claim 14, Wherein the metal film is connected between the P-type semiconductor region and the N-type semiconductor region in such a manner that a capacitance value of a parasitic capacitance formed between the P-type semiconductor region and the N-type semiconductor region with respect to the metal film opposed to each other through the insulating film is large. 16. The method of claim 15, In the thin film photodiode, a width of the P-type semiconductor region in a direction perpendicular to a direction connecting to the N-type semiconductor region and a width of the N-type semiconductor region in a direction perpendicular to a direction connecting to the P- Are formed to have different widths. 17. The method of claim 16, The metal film is connected to the N-type semiconductor region, In the thin film photodiode, a width of the P-type semiconductor region in a direction perpendicular to a direction connecting to the N-type semiconductor region is larger than a width of the P-type semiconductor region in a direction perpendicular to a direction connecting the P- Is narrower than the width of the display device. 16. The method of claim 15, The metal film is connected to the P-type semiconductor region, In the thin film photodiode, a width of the P-type semiconductor region in a direction perpendicular to a direction connecting to the N-type semiconductor region is larger than a width of the P-type semiconductor region in a direction perpendicular to a direction connecting the P- Of the display device. 16. The method of claim 15, Wherein the thin film photodiode has an intrinsic semiconductor region between the N-type semiconductor region and the P-type semiconductor region, or a low-concentration semiconductor region having a lower conductive impurity concentration than the N-type semiconductor region and the P-type semiconductor region.

Images