JP2001312223A - Self-luminous device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve emission failure in an EL device due to failure in the film forming process of an organic EL material in an electrode hole 46. SOLUTION: An insulating material is embedded in the electrode hole 46 on a pixel electrode to form a protection part 41b, and then the organic EL material is formed into a film. Thus, failure in the film forming process in the electrode hole 46 can be prevented. Thereby, concentration of currents due to a short circuit between the cathode and anode of the EL device can be prevented and emission failure of the EL layer can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a self-luminous device (EL)
Display device). In particular, a self-luminous device in which an EL element having a structure in which an anode, a cathode, and a light-emitting organic material capable of obtaining EL (Electro Luminescence) (hereinafter referred to as an organic EL material) are sandwiched therebetween is formed on an insulator, and the self-luminous device. The present invention relates to a method for manufacturing an electric appliance including a light-emitting device as a display portion (display display or display monitor).

[0002]

2. Description of the Related Art In recent years, a display device using an EL element as a self-luminous element utilizing the EL phenomenon of a luminescent organic material (EL
Display device) is under development. Since the EL display device is of a self-luminous type, it does not require a backlight like a liquid crystal display device, and has a wide viewing angle, so that it is promising as a display portion of electric appliances.

There are two types of EL display devices, a passive type (simple matrix type) and an active type (active matrix type), and both are being actively developed. In particular, an active matrix type EL display device has attracted attention at present. Low molecular organic EL materials and high molecular weight (polymer) organic EL materials have been studied as the organic EL material for the EL layer which can be said to be the center of the EL element. The polymer organic EL material is formed by a coating method using a spinner.

In both cases of the low molecular weight organic EL material and the high molecular weight (polymer type) organic EL material, if the surface on which the film is formed is not flattened, the EL material is formed into a uniform film thickness. A problem arises that it is not possible.

[0005] Further, when the thickness of the EL layer is not uniform and the EL layer is not formed partially at the step, the cathode,
When an EL element composed of an EL layer and an anode is formed, an electrical short circuit occurs between the cathode and the anode.

When a short circuit occurs between the cathode and the anode,
Current concentrates and flows between the cathode and the anode, and almost no current flows through the EL layer. This gives E
The L layer does not emit light.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method for manufacturing an EL display device by improving the structure of an EL element. Another object is to provide an electric appliance having such an EL display device as a display portion.

[0008]

In order to achieve the above object, according to the present invention, an insulator is buried so as to flatten an uneven portion of a film forming surface when forming an organic EL material for forming an EL layer. A structure for preventing a short circuit between a cathode and an anode in an EL element is adopted. Here, FIG. 1 shows a cross-sectional structure of a pixel portion of an EL display device according to the present invention.

FIG. 1A shows a pixel electrode 40.
The switching element electrically connected to (specifically,
Thin film transistor (TFT)
This is referred to as a current controlling TFT in this specification. The current control TFT includes an active layer including a source region 31, a drain region 32, and a channel formation region 34, a gate insulating film 18, a gate electrode 35, a first interlayer insulating film after a base film 12 is formed on a substrate 11. 20, a source wiring 36 and a drain wiring 37 are formed. The gate electrode 35 has a single gate structure, but may have a multi-gate structure.

Next, reference numeral 38 denotes a first passivation film having a thickness of 10 nm to 1 μm (preferably 200 to 50 μm).
0 nm). As a material, an insulating film containing silicon (in particular, a silicon nitride oxide film or a silicon nitride film is preferable) can be used.

On the first passivation film 38, a second interlayer insulating film (which may be referred to as a flattening film) 39 is formed so as to cover each TFT, and a step formed by the TFT is flattened. . As the second interlayer insulating film 39, an organic resin film is preferable, and a material such as a resin containing a high molecular compound of polyimide, polyamide, acrylic resin, and siloxane is preferably used. Of course, if sufficient planarization is possible, an inorganic film may be used.

It is very important that the step caused by the TFT is flattened by the second interlayer insulating film 39. Since an EL layer formed later is extremely thin, poor light emission may be caused by the presence of a step. Therefore, it is desirable that the EL layer be flattened before forming the pixel electrode so that the EL layer can be formed as flat as possible.

Reference numeral 40 denotes a pixel electrode (corresponding to an anode of an EL element) made of a transparent conductive film, and after opening a contact hole (opening) in the second interlayer insulating film 39 and the first passivation film 38, The opening is formed so as to be connected to the drain wiring 37 of the current controlling TFT.

In the present invention, a conductive film made of a compound of indium oxide and tin oxide is used as a pixel electrode. Further, a small amount of gallium may be added thereto. Further, a compound of indium oxide and zinc oxide or a compound of zinc oxide and gallium oxide can also be used.

[0015] A concave portion formed after the pixel electrode is formed on the contact hole is referred to as an electrode hole in this specification. After the pixel electrode is formed, an EL material is formed to form an EL layer. At this time, the thickness of the EL layer in the thin film region 47 in the electrode hole 46 is reduced as shown in FIG. Although the degree to which the film thickness is reduced depends on the taper angle of the electrode hole, a portion of the film formation surface that is not perpendicular to the film formation direction tends to be difficult to form a film and to have a small film thickness.

However, when the EL layer formed here becomes thinner and a broken part is formed, the cathode and the anode in the EL element are short-circuited, and current concentrates on this short-circuited part. Will flow. As a result, no current flows through the EL layer, so that the EL element does not emit light.

Therefore, in order to prevent a short circuit between the cathode and the anode in the EL element, an organic resin film is formed on the pixel electrode so as to sufficiently fill the electrode hole 46, and this is patterned to form the protection portion 41b. . That is, the protection unit 41
b is formed so as to fill the electrode hole. Note that a protective portion (not shown) may be formed by using an organic resin film to fill the gap between the pixel electrodes.

The organic resin film is formed by a spin coating method, is exposed using a resist mask, and is then etched to form a protective portion 41b as shown in FIG.

The protective portion 41b has a thickness of 0.1 to 1 μm, preferably 0.1 to 1 μm, at a portion raised from the pixel electrode when viewed from the cross section (a portion indicated by Da in FIG. 1C).
０．５0.5 μm, more preferably 0.1-0.3 μm.

An organic resin is preferably used for the protection portion 41b.
Polyimide, polyamide, acrylic resin and silicone
Using a material such as a resin containing a high-molecular compound of oxane
Good to be. Furthermore, when using these organic resins,
Viscosity of 10^-3Pa · s-10 ^-1It is good to be Pa · s.

After the protection portion 41b is formed, FIG.
As shown in FIG. 5, an EL layer 42 is formed, and a cathode 43 is further formed. The EL material forming the EL layer 42 may be a low molecular organic EL material,
L material may be used.

With the structure as shown in FIG. 1C as described above, the gap between the pixel electrode 40 and the cathode 43 generated when the EL layer 42 is cut at the step of the electrode hole 46. The problem of short circuit can be solved.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a cross-sectional view of a pixel portion of the EL display device according to the present invention, and FIG.
FIG. 3B is a top view, and FIG. 3B is a circuit configuration thereof. Actually, a plurality of pixels are arranged in a matrix to form a pixel portion (image display portion). Note that FIG. 2A is a cross-sectional view taken along a line AA ′ in FIG. 2 and 3
, A common reference numeral is used, so it is better to refer to both drawings as appropriate. Although two pixels are shown in the top view of FIG. 3, both have the same structure.

In FIG. 2, reference numeral 11 denotes a substrate, and 12 denotes an insulating film serving as a base (hereinafter referred to as a base film). As the substrate 11, glass, glass ceramics, quartz, silicon,
A substrate made of ceramics, metal, or plastic can be used.

The base film 12 is particularly effective when a substrate containing mobile ions or a substrate having conductivity is used, but the base film 12 may not be provided on a quartz substrate. As the base film 12, an insulating film containing silicon (silicon) may be used. Note that in this specification, the “insulating film containing silicon” specifically includes silicon, oxygen, or nitrogen at a predetermined ratio, such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film (indicated by SiOxNy). Refers to an insulating film.

Dispersing the heat generated by the TFT by giving the base film 12 a heat radiation effect is also effective for preventing the deterioration of the TFT or the EL element. All known materials can be used to provide a heat radiation effect.

Here, two TFTs are formed in a pixel. Reference numeral 201 denotes a switching TFT formed of an n-channel TFT, and reference numeral 202 denotes a current control TFT formed of a p-channel TFT.

However, in the present invention, it is not necessary to limit the switching TFT to an n-channel TFT and the current control TFT to a p-channel TFT. The switching TFT is a p-channel TFT and the current control TFT is an n-channel TFT. It is also possible to use an n-type TFT or a p-type TFT for both.

The switching TFT 201 includes a source region 13, a drain region 14, LDD regions 15a to 15d,
High concentration impurity region 16 and channel forming regions 17a, 1
Active layer including 7b, gate insulating film 18, gate electrode 19
a, 19b, a first interlayer insulating film 20, a source wiring 21, and a drain wiring 22.

Further, as shown in FIG.
A and 19b have a double gate structure electrically connected by a gate wiring 211 formed of another material (a material having a lower resistance than the gate electrodes 19a and 19b). Needless to say, not only a double gate structure but also a so-called multi-gate structure such as a single gate or triple gate structure (a structure including an active layer having two or more channel forming regions connected in series) may be used. The multi-gate structure is extremely effective in reducing the off-current value,
In the present invention, a switching element 201 having a low off-current value is realized by forming the switching element 201 of a pixel with a multi-gate structure.

The active layer is formed of a semiconductor film having a crystal structure. That is, a single crystal semiconductor film, a polycrystalline semiconductor film, or a microcrystalline semiconductor film may be used. Further, the gate insulating film 18 may be formed using an insulating film containing silicon. As the gate electrode, the source wiring, or the drain wiring, any conductive film can be used.

Further, in the switching TFT 201, the LDD regions 15a to 15d
Are provided so as not to overlap with the gate electrodes 19a and 19b. Such a structure is very effective in reducing the off-current value.

It is more preferable to provide an offset region (a region made of a semiconductor layer having the same composition as the channel forming region and to which no gate voltage is applied) between the channel forming region and the LDD region in order to reduce the off-current value. . In the case of a multi-gate structure including two or more gate electrodes, a high-concentration impurity region provided between channel formation regions is effective in reducing an off-current value.

Next, the current control TFT 202 comprises a source region 31, a drain region 32 and a channel forming region 34.
, A gate insulating film 18, a gate electrode 35, a first interlayer insulating film 20, a source wiring 36 and a drain wiring 37. The gate electrode 35 has a single gate structure, but may have a multi-gate structure.

As shown in FIG. 2, the switching TFT
Is connected to the gate of the current control TFT 202. Specifically, the gate electrode 35 of the current controlling TFT 202 is electrically connected to the drain region 14 of the switching TFT 201 via the drain wiring (also referred to as connection wiring) 22. The source wiring 36 is connected to the power supply line 212.

The current controlling TFT 202 is an EL element 203
Is an element for controlling the amount of current injected into the
Considering the deterioration of the L element, it is not preferable to flow too much current. Therefore, it is preferable to design the channel length (L) to be longer so that an excessive current does not flow through the current controlling TFT 202. Desirably, it is 0.5 to 2 μA (preferably 1 to 1.5 μA) per pixel.

The length (width) of the LDD region formed in the switching TFT 201 is 0.5 to 3.5 μm.
Typically, the thickness may be 2.0 to 2.5 μm.

Also, as shown in FIG.
The wiring 36 serving as the gate electrode 35 of 202 overlaps with the semiconductor film 51 formed simultaneously with the active layer via the gate insulating film in the region indicated by 50. At this time, a capacitor is formed in a region indicated by 50 and functions as a storage capacitor 50 for holding a voltage applied to the gate electrode 35 of the current control TFT 202. Further, the storage capacitor 50 also forms a capacitor formed by the wiring 36 serving as a gate electrode, a first interlayer insulating film (not shown), and a power supply line 212. In addition,
The drain of the current control TFT is connected to the power supply line 212, and a constant voltage is constantly applied.

From the viewpoint of increasing the amount of current that can flow, the thickness of the active layer (particularly, the channel formation region) of the current controlling TFT 202 is increased (preferably 50).
To 100 nm, more preferably 60 to 80 nm). Conversely, in the case of the switching TFT 201, from the viewpoint of reducing the off-current value, the thickness of the active layer (particularly, the channel formation region) is reduced (preferably 20 to 50 nm, more preferably 25 to 40 n).
m) is also effective.

Next, reference numeral 38 denotes a first passivation film having a thickness of 10 nm to 1 μm (preferably 200 to 50 μm).
0 nm). As a material, an insulating film containing silicon (in particular, a silicon nitride oxide film or a silicon nitride film is preferable) can be used.

On the first passivation film 38, a second interlayer insulating film (which may be referred to as a flattening film) 39 is formed so as to cover each TFT, and a step formed by the TFT is flattened. . As the second interlayer insulating film 39, an organic resin film made of an organic resin is preferable.
It is preferable to use a material such as a resin containing a high molecular compound of polyimide, polyamide, and siloxane. Of course, a film made of an inorganic material may be used as long as sufficient planarization is possible.

It is very important that the step caused by the TFT is flattened by the second interlayer insulating film 39. Since an EL layer formed later is extremely thin, poor light emission may be caused by the presence of a step. Therefore, it is desirable that the EL layer be flattened before forming the pixel electrode so that the EL layer can be formed as flat as possible.

Reference numeral 40 denotes a pixel electrode (corresponding to an anode of an EL element) made of a transparent conductive film. After a contact hole (opening) is formed in the second interlayer insulating film 39 and the first passivation film 38, The opening is formed so as to be connected to the drain wiring 37 of the current controlling TFT 202.

In this embodiment, a conductive film made of a compound of indium oxide and tin oxide is used as a pixel electrode. Further, a small amount of gallium may be added thereto. Further, a compound of indium oxide and zinc oxide can be used.

Next, an organic resin film made of an organic resin is formed on the pixel electrode by spin coating so as to fill the electrode hole 46 on the pixel electrode. Here, an acrylic resin is used as the organic resin film.

Although an organic resin film made of an organic resin is formed on the pixel electrode, an insulator that can serve as an insulating film may be used. Note that as the insulator, an inorganic material containing silicon such as silicon oxide, silicon nitride oxide, or silicon nitride may be used.

After an acrylic resin film is formed on the entire surface, exposure is performed using a resist mask and etching is performed to form protective portions 41a and 41b shown in FIG.

The protection portion 41b is a portion where the electrode hole in the pixel electrode is buried with acrylic resin. Further, the protection unit 41a is provided in a gap between the pixel electrodes. The gap between the pixel electrodes refers to a portion where the pixel electrode is not formed, for example, a portion between the pixel electrodes in the pixel portion where a plurality of pixel electrodes are formed.
This is because, when etching is performed to form the protective portion, if the material forming the second interlayer insulating film is the material forming the protective portion, the second interlayer insulating film is simultaneously etched between the pixel electrodes. This is because there is a possibility that it will be lost.

The protective portions 41a and 41b have a thickness of 0.1 to 1 μm, preferably 0.1 to 0.5 μm, more preferably 0.1 to 1 μm at a portion raised from the pixel electrode when viewed from the cross section. The thickness is preferably 0.3 μm.

Although an acrylic resin is used as the organic resin for the protection portions 41a and 41b, a resin containing a high-molecular compound of siloxane such as polyimide, polyamide, and cycloten may be used as the material. good. Furthermore, when using these organic resins, the viscosity is preferably set to 10 ⁻³ Pa · s to 10 ⁻¹ Pa · s.

The protection section 41b is provided as described above,
By filling the electrode holes with an organic resin, the pixel electrode 40 (anode) and the cathode 43 generated when the EL layer 42 is cut.
The problem of short circuit between them can be solved.

A method for manufacturing the protection portion 41b will be described with reference to FIG. FIG. 4A shows a structure in which an organic resin film is formed on the pixel electrode 40, and then a protective portion 41b is formed by patterning. Da is the thickness of the organic resin film. When the thickness is reduced, the protection portion 41b of FIG.
A depression is formed in the upper part as shown in FIG.

The degree of the depression depends on the taper angle of the electrode hole and the thickness of the organic resin film. However, if the thickness of the organic resin film is extremely thin, the electrode hole cannot be completely buried. May not be able to fulfill their role.

On the other hand, when the thickness of the organic resin film is increased, a step is generated again. Therefore, as a method of solving this, as shown in FIG. 4B, after forming an organic resin film with a film thickness of Db, a protective portion 41b is formed by patterning, and the entire surface is etched to reduce the film thickness. Da.
Thereby, as shown in FIG. 4C, the upper portion is flattened, and the protective portion 41b having an appropriate film thickness can be formed.

However, when the method shown in FIG. 4B is used, the pixel electrode exposed on the surface during the etching after the patterning of the protection portion 41b is also exposed to the etching environment. Therefore, a manufacturing method in consideration of this point will be described with reference to FIGS.

First, as shown in FIG.
An organic resin film having a thickness of Db is formed on the substrate 0. This is made into a film thickness Da by etching the entire surface. Further, this is patterned to form a protection portion 41b.

The protective portion 41b may be formed by forming an organic resin film and then patterning it as shown in FIG. 4A, or by etching the entire surface after patterning as shown in FIG. 4B. It may be formed by performing. further,
As shown in FIG. 5A, the entire surface may be etched and then patterned.

As shown in FIG. 5, the outer diameter Rb of the protection portion 41b
Is such that Rb> Ra with respect to the inner diameter Ra of the electrode hole 46. Note that the protection portion 41b described with reference to FIG. 4 or FIG. 5 has a structure illustrated in FIG. That is, the solid line of 41b in FIG. 5C matches the outer shape of the protection portion 41b, and the broken line of 41b in FIG.
6. It corresponds to the inner diameter of 6.

Next, an EL layer 42 is formed. here,
A method in which a polymer organic EL material dissolved in a solvent is formed by spin coating to form an EL layer will be described.
Here, as an organic EL material for forming the EL layer,
Although a case where a high molecular weight organic EL material is used will be described as an example, a low molecular weight organic EL material can be used.

Typical polymer organic EL materials include:
Examples thereof include polyparaphenylene vinylene (PPV), polyvinyl carbazole (PVK), and polyfluorene.

There are various types of PPV-based organic EL materials, and for example, the following molecular formulas have been published. ("H. Shenk, H. Becker, O. Gelsen, E. Kluge, W. Kreuder, a
nd H. Spreitzer, “Polymers for Light Emitting Diode
s ”, Euro Display, Proceedings, 1999, pp. 33-37”)

[0062]

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[0063]

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Further, polyphenylvinyl having a molecular formula described in JP-A-10-92576 can also be used. The molecular formula is as follows.

[0065]

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[0066]

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The PVK-based organic EL material has the following molecular formula.

[0068]

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The polymer organic EL material can be applied by dissolving it in a solvent in a polymer state or by dissolving it in a solvent in a monomer state and applying it. When applied in the form of a monomer, a polymer precursor is first formed and polymerized by heating in a vacuum to form a polymer.

As specific EL layers, cyanopolyphenylenevinylene is used for an EL layer emitting red light, polyphenylenevinylene is used for an EL layer emitting green light, and polyphenylenevinylene or polyalkylphenylene is used for an EL layer emitting blue light. Good. The film thickness is 30-150n
m (preferably 40 to 100 nm).

However, the above example is an example of the organic EL material that can be used for the EL layer of the present invention, and it is not necessary to limit to this.

Typical solvents for dissolving the organic EL material include toluene, xylene, chlorobenzene, dichlorobenzene, anisole, chloroform, dichloromethane, γ-butyl lactone, butyl cellosolve, cyclohexane, NMP (N-methyl-2- Pyrrolidone),
Solvents such as cyclohexanone, dioxane, or THF (tetrahydrofuran) are exemplified.

Further, when the EL layer 42 is formed, the EL layer is easily deteriorated by the presence of moisture or oxygen. It is desirable to do. Further, the processing atmosphere may be set to the used solvent atmosphere because the evaporation rate of the solvent in which the EL material is dissolved can be controlled. In order to implement these,
It is desirable that the thin film forming apparatus shown in FIG. 1 is installed in a clean booth filled with an inert gas, and the light emitting layer is formed in that atmosphere.

As a method for forming the EL layer, an ink jet method or the like may be used in addition to the spin coating method described here.

Further, an EL using a low molecular organic EL material is used.
When a layer is formed, an evaporation method or the like can be used. Note that a known material can be used as the low-molecular-weight organic EL material.

After the EL layer 42 is formed as described above, the cathode 43 and the protection electrode 44 made of a light-shielding conductive film are next formed.
And a second passivation film 45 is formed. In the present embodiment, a conductive film made of MgAg is used as the cathode 43, and a conductive film made of aluminum is used as the protective electrode 44. Further, as the second passivation film 45,
A silicon nitride film having a thickness of 10 nm to 1 μm (preferably 200 to 500 nm) is used.

Since the EL layer is weak to heat as described above, the cathode 43 and the second passivation film 45 are kept as low as possible (preferably in a temperature range from room temperature to 120 ° C.).
It is desirable to form a film. Therefore, the plasma CVD method,
It can be said that a vacuum deposition method or a solution coating method (spin coating method) is a desirable film forming method.

The completed substrate is called an active matrix substrate, and a counter substrate (not shown) is provided to face the active matrix substrate. In this embodiment, a glass substrate is used as a counter substrate. Note that a substrate made of plastic or ceramic may be used as the counter substrate.

Further, the active matrix substrate and the counter substrate are adhered by a sealant (not shown) to form a closed space (not shown). In the present embodiment, the closed space is filled with argon gas. Of course, it is also possible to arrange a desiccant such as barium oxide or an antioxidant in the enclosed space.

Further, when a metal having a low work function and which is easily oxidized or a hygroscopic metal is formed on the surface of the counter substrate on the side of the active matrix substrate, a function of capturing oxygen and a function of absorbing moisture may be provided. it can. It is more effective to form a film of these metals after forming unevenness on the counter substrate with an organic resin such as a photosensitive acrylic resin because the surface area can be increased.

[0081]

[Embodiment 1] A method for simultaneously manufacturing TFTs of a pixel portion and a driving circuit portion provided around the pixel portion in the embodiment of the present invention will be described with reference to FIGS. However, for the sake of simplicity, a CMOS circuit, which is a basic circuit, is illustrated for the drive circuit.

First, as shown in FIG. 6A, a base film 301 is formed on a glass substrate 300 to a thickness of 300 nm. In this embodiment, a 100-nm-thick silicon nitride oxide film and a 200-nm silicon nitride oxide film are stacked and used as the base film 301. At this time, the nitrogen concentration in contact with the glass substrate 300 is preferably set to 10 to 25 wt%. Of course, an element may be formed directly on a quartz substrate without providing a base film.

Next, an amorphous silicon film (not shown) having a thickness of 50 nm is formed on the base film 301 by a known film forming method. Note that the present invention is not limited to an amorphous silicon film, and may be any semiconductor film including an amorphous structure (including a microcrystalline semiconductor film). Further, a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be used. The film thickness is 2
The thickness may be 0 to 100 nm.

Then, the amorphous silicon film is crystallized by a known technique, and a crystalline silicon film (also called a polycrystalline silicon film or a polysilicon film) 302 is formed. Known crystallization methods include a thermal crystallization method using an electric furnace, a laser annealing crystallization method using laser light, and a lamp annealing crystallization method using infrared light. In this embodiment, X
Crystallization is performed using excimer laser light using eCl gas.

In this embodiment, a pulse oscillation type excimer laser beam processed into a linear shape is used, but a rectangular shape may be used, or a continuous oscillation type argon laser beam or a continuous oscillation type excimer laser beam may be used. You can also.

In this embodiment, a crystalline silicon film is used as an active layer of a TFT, but an amorphous silicon film can be used. Further, it is also possible to form the active layer of the switching TFT, which needs to reduce the off current, with an amorphous silicon film, and to form the active layer of the current control TFT with a crystalline silicon film. Since the amorphous silicon film has a low carrier mobility, it is difficult for an electric current to flow and an off current is hard to flow. That is, the advantages of both an amorphous silicon film through which a current is hard to flow and a crystalline silicon film through which a current easily flows can be utilized.

Next, as shown in FIG. 6B, a protective film 303 made of a silicon oxide film is
It is formed to a thickness of 0 nm. This thickness is 100-200n
m (preferably 130 to 170 nm). Further, any other insulating film containing silicon may be used.
The protective film 303 is provided to prevent the crystalline silicon film from being directly exposed to plasma when adding impurities and to enable fine concentration control.

Then, a resist mask 304 is formed thereon.
a and 304b are formed, and an impurity element imparting n-type (hereinafter, referred to as an n-type impurity element) is added via the protective film 303. Note that the n-type impurity element is typically 15
Elements belonging to the group, typically phosphorus or arsenic, can be used. In this embodiment, the plasma (ion) in which phosphine (PH ₃ ) is plasma-excited without mass separation.
Using a doping method, phosphorus is added at a concentration of 1 × 10 ¹⁸ atoms / cm ³ . Of course, an ion implantation method for performing mass separation may be used.

In the n-type impurity region 305 formed by this step, the n-type impurity element is 2 × 10 ^{16 to} 5 × 10 ¹⁹
atoms / cm ³ (typically 5 × 10 ^{17 to} 5 × 10 ¹⁸ atoms / c
Adjust the dose so that it is contained at a concentration of m ³ ).

Next, as shown in FIG.
03 and the resists 304a and 304b are removed, and the added element belonging to Group 15 is activated. As the activating means, a known technique may be used. In this embodiment, the activating means is activated by excimer laser light irradiation. Needless to say, a pulse oscillation type or a continuous oscillation type may be used, and it is not necessary to limit to an excimer laser beam. However, since the purpose is to activate the added impurity element, it is preferable that the irradiation be performed with energy that does not melt the crystalline silicon film. The protective film 30
The laser beam may be irradiated with 3 attached.

When activating the impurity element by the laser beam, activation by heat treatment may be used in combination. When activation by heat treatment is performed, heat treatment at about 450 to 550 ° C. may be performed in consideration of the heat resistance of the substrate.

By this step, the n-type impurity region 305, ie, the n-type impurity region
The boundary (junction) with the region where the type impurity element is not added becomes clear. This means that when the TFT is completed later, a very good junction can be formed between the LDD region and the channel forming region.

Next, as shown in FIG. 6D, unnecessary portions of the crystalline silicon film are removed, and an island-shaped semiconductor film (hereinafter, referred to as an island-shaped semiconductor film) is formed.
306 to 309 are formed.

Next, as shown in FIG.
A gate insulating film 310 is formed so as to cover 06 to 309.
As the gate insulating film 310, an insulating film containing silicon with a thickness of 10 to 200 nm, preferably 50 to 150 nm may be used. This may have a single-layer structure or a laminated structure. In this embodiment, a 110-nm-thick silicon nitride oxide film is used.

Next, a conductive film having a thickness of 200 to 400 nm is formed and patterned to form gate electrodes 311 to 315. The ends of the gate electrodes 311 to 315 can be tapered. Note that in this embodiment, the gate electrode and a wiring for wiring (hereinafter, referred to as a gate wiring) electrically connected to the gate electrode are formed using different materials. Specifically, a material having lower resistance than the gate electrode is used for the gate wiring. This is because a material that can be finely processed is used for the gate electrode, and a material that does not allow fine processing and has low wiring resistance is used for the gate wiring.
Of course, the gate electrode and the gate wiring may be formed of the same material.

The gate electrode may be formed of a single-layer conductive film, but is preferably formed as a two-layer or three-layer film as required. As a material for the gate electrode, any known conductive film can be used. However, a material that can be finely processed as described above, specifically, a material that can be patterned into a line width of 2 μm or less is preferable.

Typically, tantalum (Ta), titanium (Ti), molybdenum (Mo), tungsten (W),
A film made of an element selected from chromium (Cr) and silicon (Si), a nitride film of the above element (typically, a tantalum nitride film, a tungsten nitride film, a titanium nitride film), or an alloy combining the above elements Membrane (typically Mo-
A W alloy, a Mo—Ta alloy) or a silicide film of the above element (typically, a tungsten silicide film or a titanium silicide film) can be used. Of course, they may be used as a single layer or stacked.

In this embodiment, a laminated film composed of a 50 nm thick tantalum nitride (TaN) film and a 350 nm thick tantalum (Ta) film is used. This may be formed by a sputtering method. When an inert gas such as Xe or Ne is added as a sputtering gas, the film can be prevented from peeling due to stress.

At this time, the gate electrode 312 is formed so as to overlap a part of the n-type impurity region 305 with the gate insulating film 310 interposed therebetween. This overlapping portion later becomes an LDD region overlapping with the gate electrode. The gate electrode 31
3 and 314 appear to be two in cross section, but are actually electrically connected.

Next, as shown in FIG. 7A, an n-type impurity element (phosphorus in this embodiment) is added in a self-aligned manner using the gate electrodes 311 to 315 as a mask. The n-type impurity regions 3 are formed in the impurity regions 316 to 323 thus formed.
1/2 to 1/10 of 05 (typically 1/3 to 1/4)
Adjust so that phosphorus is added at a concentration of. Specifically, 1 × 10 ^{16 to} 5 × 10 ¹⁸ atoms / cm ³ (typically ³ × 10 ¹⁶ atoms / cm 3
A concentration of × 10 ^{17 to} 3 × 10 ¹⁸ atoms / cm ³ ) is preferable.

Next, as shown in FIG. 7B, resist masks 324a to 324d are formed so as to cover the gate electrodes and the like, and an n-type impurity element (phosphorus in this embodiment) is added to increase the concentration. The impurity regions 325 to 329 containing phosphorus are formed. Also in this case, the ion doping method using phosphine (PH ₃ ) is performed, and the concentration of phosphorus in this region is 1 × 10 ²⁰ to 1 ×.
10 ²¹ atoms / cm ³ (typically 2 × 10 ^{20 to} 5 × 10 ²¹ a
Adjust to be toms / cm ³ ).

In this step, the source region and the drain region of the n-channel TFT are formed. In the switching TFT, a part of the n-type impurity regions 319 to 321 formed in the step of FIG. This remaining area is the LDD of the switching TFT 201 in FIG.
This corresponds to the areas 15a to 15d.

Next, as shown in FIG. 7C, the resist masks 324a to 324d are removed, and a new resist mask 332 is formed. Then, a p-type impurity element (boron in this embodiment) is added to form impurity regions 333 to 336 containing boron at a high concentration. Here, an ion doping method using diborane (B ₂ H ₆ ) is used to form 3 × 10 ²⁰ to
3 × 10 ²¹ atoms / cm ³ (typically 5 × 10 ²⁰ to 1 × 1
(Boron) is added so as to have a concentration of 0 ²¹ atoms / cm ³ .

It is to be noted that phosphorus is already added to impurity regions 333 to 336 at a concentration of 1 × 10 ²⁰ to 1 × 10 ²¹ atoms / cm ³ , and the boron added here is at least three times as large as that. It is added at a concentration. Therefore, the n-type impurity region formed in advance is completely inverted to p-type, and functions as a p-type impurity region.

Next, after removing the resist mask 332, the n-type or p-type impurity element added at each concentration is activated. As the activation means, a furnace annealing method, a laser annealing method, and a lamp annealing method can be used. In this embodiment, heat treatment is performed in an electric furnace at 550 ° C. for 4 hours in a nitrogen atmosphere.

At this time, it is important to eliminate oxygen in the atmosphere as much as possible. This is because the presence of even a small amount of oxygen oxidizes the exposed surface of the gate electrode, causing an increase in resistance and making it difficult to obtain an ohmic contact later. Therefore, the oxygen concentration in the processing atmosphere in the activation step is 1 ppm or less, preferably 0.1 ppm or less.
pm or less.

Next, when the activation step is completed, FIG.
A gate wiring 337 having a thickness of 300 nm is formed as shown in FIG. As a material of the gate wiring 337, aluminum (Al) or copper (Cu) is a main component (composition of 50 to 1).
Accounts for 00%. ) May be used. As an arrangement, as shown in FIG. 3, the gate wiring 211 and the gate electrodes 19a and 19b of the switching TFT (31 in FIG.
3, 314) are formed so as to be electrically connected.

With such a structure, the wiring resistance of the gate wiring can be extremely reduced, so that an image display region (pixel portion) having a large area can be formed. That is, the pixel structure of the present embodiment is extremely effective in realizing an EL display device having a screen size of 10 inches or more (more preferably 30 inches or more) diagonally.

Next, as shown in FIG. 8A, a first interlayer insulating film 338 is formed. As the first interlayer insulating film 338, an insulating film containing silicon may be used as a single layer or a stacked film in which two or more insulating films containing silicon are combined. The film thickness may be 400 nm to 1.5 μm. In this embodiment, an 800 nm thick silicon oxide film is stacked over a 200 nm thick silicon nitride oxide film.

Further, a heat treatment is carried out at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen to carry out a hydrogenation treatment. This step is a step of terminating dangling bonds of the semiconductor film with thermally excited hydrogen. As another means of hydrogenation, plasma hydrogenation (using hydrogen generated by plasma) may be performed.

The hydrogenation treatment is performed for the first interlayer insulating film 338.
May be inserted during formation. That is, after forming a 200-nm-thick silicon nitride oxide film, the hydrogenation treatment may be performed as described above, and then a remaining 800-nm-thick silicon oxide film may be formed.

Next, contact holes are formed in the first interlayer insulating film 338 and the gate insulating film 310, and source wirings 339 to 342 and drain wirings 343 to 345 are formed. In this embodiment, these electrodes are formed by forming a Ti film with a thickness of 100 nm and an aluminum film containing Ti with a thickness of 300 nm.
m and a Ti film having a three-layer structure in which a 150 nm thick Ti film is continuously formed by a sputtering method. Of course, other conductive films may be used.

Next, 50 to 500 nm (typically 20 to 500 nm)
The first passivation film 34 with a thickness of
6 is formed. In this embodiment, the first passivation film 3
A silicon nitride oxide film having a thickness of 300 nm is used as 46. This may be replaced by a silicon nitride film.

Note that prior to the formation of the silicon nitride oxide film, H
_2. It is effective to perform a plasma treatment using a gas containing hydrogen such as NH ₃ . Hydrogen excited by this pretreatment is supplied to the first interlayer insulating film 338 and is subjected to a heat treatment, whereby the quality of the first passivation film 346 is improved. At the same time, the hydrogen added to the first interlayer insulating film 338 diffuses to the lower layer side, so that the active layer can be effectively hydrogenated.

Next, as shown in FIG. 8B, a second interlayer insulating film 347 made of an organic resin is formed. As the organic resin, a high molecular compound of polyimide, polyamide, acrylic resin, or siloxane can be used as a material.
In particular, since the second interlayer insulating film 347 has a strong meaning of flattening, an acrylic resin having excellent flatness is preferable. In this embodiment, an acrylic resin film is formed with a thickness that can sufficiently flatten a step formed by a TFT. Preferably 1 to
The thickness may be 5 μm (more preferably, 2 to 4 μm).

Next, a contact hole is formed in the second interlayer insulating film 347 and the first passivation film 346, and a pixel electrode 348 electrically connected to the drain wiring 345 is formed. In this embodiment, an indium tin oxide (ITO) film is formed to a thickness of 110 nm and patterned to form a pixel electrode. In addition, 2 indium oxide
A transparent conductive film mixed with -20% of zinc oxide (ZnO) may be used. This pixel electrode becomes the anode of the EL element.

Next, as shown in FIG. 8C, protection portions 349a and 349b made of an organic resin are formed. The protective portions 349a and 349b may be formed by patterning a resin film such as an acrylic resin film or a polyimide film having a thickness of 1 to 2 μm. The protection parts 349a and 349b are shown in FIG.
As shown in (1), they are formed in the gaps between the pixel electrodes and the electrode holes.

Next, an EL layer 350 is formed. Specifically, the organic EL material to be the EL layer 350 is dissolved in a solvent such as chloroform, dichloromethane, xylene, toluene, tetrahydrofuran, and N-methylpyrrolidone, and applied by a spin coating method. Let it. Thus, a film (EL layer) made of the organic EL material is formed.

In this embodiment, after the EL material is formed to a thickness of 80 nm, the EL material is formed on a hot plate at 80 to 150 ° C.
Perform heat treatment for 5 minutes to volatilize.

A known material can be used as the EL material. As a known material, it is preferable to use an organic material in consideration of a driving voltage. Note that in this embodiment, the EL layer 350 has a single-layer structure. It may be a laminated structure. In this embodiment, the cathode 351 of the EL element is M
Although an example using a gAg electrode is shown, other known materials may be used.

After forming the EL layer 350, the cathode (MgA
g electrode 351 is formed by a vacuum evaporation method. The thickness of the EL layer 350 is 80 to 200 nm (typically 100 to 200 nm).
120 nm), and the thickness of the cathode 351 is 180 to 300 nm.
(Typically 200 to 250 nm).

Further, the protective electrode 35 is provided on the cathode 351.
2 is provided. As the protective electrode 352, a conductive film containing aluminum as a main component may be used. The protection electrode 352 is
It may be formed by a vacuum evaporation method using a mask.

Finally, a second passivation film 353 made of a silicon nitride film is formed to a thickness of 300 nm. Although the protection electrode 352 actually serves to protect the EL layer from moisture and the like, the reliability of the EL element can be further increased by forming the second passivation film 353 further.

In the case of the present embodiment, as shown in FIG. 8C, the active layer of the n-channel type
5, a drain region 356, an LDD region 357, and a channel formation region 358. The LDD region 357 overlaps with the gate electrode 312 with the gate insulating film 310 interposed therebetween.

The reason why the LDD region is formed only on the drain region side is to avoid lowering the operation speed.
Further, the n-channel TFT 205 does not need to care much about the off-current value, and it is better to emphasize the operation speed. Therefore, it is desirable that the LDD region 357 be completely overlapped with the gate electrode and the resistance component be reduced as much as possible. That is, it is better to eliminate the so-called offset.

Thus, an active matrix substrate having a structure as shown in FIG. 8C is completed.

By the way, the active matrix substrate of this embodiment exhibits extremely high reliability by arranging the TFT having the optimum structure not only in the pixel portion but also in the drive circuit portion, and the operating characteristics can be improved.

First, a TFT having a structure in which hot carrier injection is reduced so as not to lower the operation speed as much as possible,
N-channel type TF of CMOS circuit forming drive circuit section
Used as T205. Note that the drive circuit here includes a shift register, a buffer, a level shifter, a sampling circuit (a sample and hold circuit), and the like. When digital driving is performed, a signal conversion circuit such as a D / A converter may be included.

Note that among the driving circuits, the sampling circuit is a little special as compared with other circuits, and a large current flows in both directions in the channel forming region. That is, the roles of the source region and the drain region are switched. In addition, it is necessary to keep the off-current value as low as possible, and in that sense, it is desirable to arrange a TFT having a function approximately between the switching TFT and the current control TFT.

Therefore, it is desirable to arrange a TFT having a structure as shown in FIG. 9 as the n-channel TFT forming the sampling circuit. As shown in FIG. 9, part of the LDD regions 901a and 901b overlap with the gate electrode 903 via the gate insulating film 902. This effect is a countermeasure against deterioration of hot carrier injection that occurs when current flows.
The difference is that the sampling circuit is provided on both sides with the channel formation region 904 interposed therebetween.

It is to be noted that, when actually completed up to FIG. 8C, it is preferable to package (enclose) with a cover material such as glass, quartz, or plastic with high airtightness so as not to be further exposed to the outside air. At this time, it is preferable to dispose a moisture absorbent such as barium oxide or an antioxidant inside the cover material.

When the airtightness is improved by processing such as packaging, a connector (flexible printed circuit: FPC) for connecting a terminal routed from an element or a circuit formed on the substrate to an external signal terminal. To complete the product. Such a state in which the product can be shipped is referred to as an EL display device (or EL module) in this specification.

Here, the configuration of the active matrix type EL display device of this embodiment will be described with reference to the perspective view of FIG. An active matrix EL display device according to this embodiment includes a pixel portion 602 formed on a glass substrate 601.
, The gate side drive circuit 603 and the source side drive circuit 60
4 inclusive. The switching TFT 605 of the pixel portion is an n-channel TFT, and is arranged at an intersection of a gate wiring 606 connected to the gate driver circuit 603 and a source wiring 607 connected to the source driver circuit 604. The drain of the switching TFT 605 is connected to the gate of the current control TFT 608.

Further, the source side of the current controlling TFT 608 is connected to the power supply line 609. In the structure as in this embodiment, the power supply line 609 is supplied with a ground potential (earth potential). Also, the current control TFT 608
Is connected to the EL element 610. A predetermined voltage (3 to 1) is applied to the anode of the EL element 610.
2V, preferably 3-5V) is applied.

An FPC 61 serving as an external input / output terminal
1 is a connection wiring 6 for transmitting a signal to the drive circuit unit.
12, 613 and a connection wiring 614 connected to the power supply line 609 are provided.

FIG. 11 shows an example of a circuit configuration of the EL display device shown in FIG. The EL display device according to this embodiment includes a source-side drive circuit 801 and a gate-side drive circuit (A).
807, a gate side driver circuit (B) 811, a pixel portion 806
have. Note that in this specification, a drive circuit portion is a general term including a source-side drive circuit and a gate-side drive circuit.

The source side drive circuit 801 includes a shift register 802, a level shifter 803, a buffer 804, and a sampling circuit (sample and hold circuit) 805. The gate side driver circuit (A) 807 includes a shift register 808, a level shifter 809, and a buffer 8
10 is provided. The gate side drive circuit (B) 811 has the same configuration.

The shift registers 802 and 808 have a driving voltage of 5 to 16 V (typically 10 V), and are n-channel TFTs used in a CMOS circuit forming the circuit.
Is suitable for the structure shown by 205 in FIG.

The level shifters 803 and 809 and the buffers 804 and 810 are similar to the shift registers in FIG.
A CMOS circuit including the n-channel TFT 205 shown in FIG. The gate wiring has a double gate structure,
The use of a multi-gate structure such as a triple gate structure is effective in improving the reliability of each circuit.

Since the source and drain regions of the sampling circuit 805 are inverted and the off-current value needs to be reduced, a CMOS circuit including the n-channel TFT 208 shown in FIG. 9 is suitable.

In the pixel portion 806, pixels having the structure shown in FIG. 2 are arranged.

The above configuration can be easily realized by manufacturing a TFT according to the manufacturing steps shown in FIGS. Although only the configuration of the pixel portion and the drive circuit portion is shown in this embodiment, other components such as a signal division circuit, a D / A converter circuit, an operational amplifier circuit, a γ correction circuit, and the like can be used according to the manufacturing process of this embodiment. It is considered that a logic circuit other than a driver circuit can be formed over the same substrate, and that a memory portion, a microprocessor, and the like can be formed.

Further, the E of this embodiment including the cover material
The L module will be described with reference to FIGS. Note that the reference numerals used in FIGS. 10 and 11 will be referred to as needed.

FIG. 12A is a top view showing a state where a sealing structure is provided in the state shown in FIG. 602 indicated by a dotted line is a pixel portion, 603 is a gate side driving circuit,
604 is a source side drive circuit. The sealing structure of the present invention is a structure in which a filler (not shown), a cover material 1101, a seal material (not shown), and a frame material 1102 are provided in the state of FIG.

Here, FIG. 12B is a cross-sectional view taken along the line AA ′ of FIG. Note that FIG.
In (B), the same reference numerals are used for the same parts.

As shown in FIG. 12B, a pixel portion 602 and a gate side driving circuit 603 are formed on a substrate 601, and the pixel portion 602 includes a current control TFT 202 and a pixel electrically connected thereto. It is formed by a plurality of pixels including the electrode 348. The gate side drive circuit 603 is n
It is formed using a CMOS circuit in which a channel type TFT 205 and a p-channel type TFT 206 are complementarily combined.

The pixel electrode 348 functions as an anode of the EL element. Further, protective films 349 are provided on both ends of the pixel electrode 348.
is formed, and an EL layer 350 and a cathode 351 are formed on the protective film 349a. In addition, a protective electrode 35 is provided thereon.
2. A second passivation film 353 is formed. Of course, as described above, the structure of the EL element may be reversed, and the pixel electrode may be a cathode.

In the case of this embodiment, the protection electrode 352 also functions as a common wiring for all pixels, and is electrically connected to the FPC 611 via the connection wiring 612. Further, the elements included in the pixel portion 602 and the gate side driver circuit 603 are all covered with the second passivation film 353.
The second passivation film 353 can be omitted, but is preferably provided to block each element from the outside.

Next, the filling material 1 was placed so as to cover the EL element.
103 is provided. This filler 1103 is used as the cover material 110.
1 also functions as an adhesive for bonding. Filling material 1
As 103, PVC (polyvinyl chloride), epoxy resin, silicon resin, PVB (polyvinyl butyral) or EVA (ethylene vinyl acetate) can be used. It is preferable to provide a desiccant (not shown) inside the filler 1103 because the moisture absorbing effect can be maintained. At this time, the desiccant may be added to the filler, or may be enclosed in the filler.

In this embodiment, as the cover material 1101, a material made of glass, plastic, and ceramics can be used. Note that the filler 1103
It is effective to add a desiccant, such as barium oxide, in advance in the inside.

Next, using the filler 1103, the cover 1
After bonding 101, the side surface (exposure surface) of filler 1103
Frame material 1102 is attached so as to cover. The frame material 1102 is a sealing material (functioning as an adhesive) 11
04. At this time, the sealing material 1104
It is preferable to use a photocurable resin as the
A thermosetting resin may be used if the heat resistance of the layer permits. Note that the sealant 1104 is preferably a material that does not transmit moisture or oxygen as much as possible. Also, the sealing material 110
A desiccant may be added to the inside of 4.

By enclosing the EL element in the filler 1103 using the above-described method, the EL element can be completely shut off from the outside, and the EL element such as moisture and oxygen can be shut off from the outside.
It is possible to prevent a substance that promotes deterioration of the L layer due to oxidation from entering. Therefore, a highly reliable EL display device can be manufactured.

[Embodiment 2] In the embodiment 1, after the organic resin is applied on the entire surface of the pixel electrode, patterning is performed using an exposure device, and the protective portion is filled with the organic resin in the electrode hole and the gap between the pixel electrodes. After the formation of the EL layer, the manufacturing method of forming the EL layer was described. However, in this embodiment, since the exposure process was performed, the throughput was poor. A method of performing planarization using a back method and etching portions other than the organic resin embedded in the gap between the electrode hole and the pixel electrode will be described.

Here, FIG. 13 shows a cross-sectional structure of a pixel portion of an EL display device according to the present invention.

FIG. 13A shows the pixel electrode 1.
040 and a current controlling TFT electrically connected to the pixel electrode 1040. The current control TFT is provided on the substrate 101.
After a base film 1012 is formed on the
31, drain region 1032 and channel formation region 10
34, an active layer including the gate insulating film 1018, a gate electrode 1035, a first interlayer insulating film 1020, a source wiring 103
6 and a drain wiring 1037. Note that the gate electrode 1035 has a single-gate structure, but may have a multi-gate structure.

Next, reference numeral 1038 denotes a first passivation film having a thickness of 10 nm to 1 μm (preferably 200 to 1 μm).
500 nm). As a material, an insulating film containing silicon (in particular, a silicon nitride oxide film or a silicon nitride film is preferable) can be used.

On the first passivation film 1038, a second interlayer insulating film (also referred to as a flattening film) 1039 is formed so as to cover each TFT, and a step formed by the TFT is flattened. . As the second interlayer insulating film 1039, an organic resin film is preferable, and a resin containing a high molecular compound of polyimide, polyamide, acrylic resin, or siloxane is preferably used as a material. Of course, if sufficient planarization is possible, an inorganic film may be used.

It is very important that the step due to the TFT is flattened by the second interlayer insulating film 1039. Since an EL layer formed later is extremely thin, poor light emission may be caused by the presence of a step. Therefore, it is desirable that the EL layer be flattened before forming the pixel electrode so that the EL layer can be formed as flat as possible.

Reference numeral 1040 denotes a pixel electrode (corresponding to an anode of an EL element) made of a transparent conductive film. After a contact hole (opening) is formed in the second interlayer insulating film 1039 and the first passivation film 1038, The opening is formed so as to be connected to the drain wiring 1037 of the current controlling TFT.

In the present embodiment, a conductive film made of a compound of indium oxide and tin oxide is used as a pixel electrode. Further, a small amount of gallium may be added thereto. Further, a compound of indium oxide and zinc oxide can be used.

Next, an organic resin film 1041 made of an organic resin is formed on the pixel electrode. As the organic resin, there are materials such as a resin containing a high molecular compound of polyamide, polyimide, acrylic resin, and siloxane, and these may be used. Here, an acrylic resin such as an acrylate resin, an acrylate resin, Resins such as acid ester resin and methacrylic acid resin are used. In addition, as a resin containing a high molecular compound of siloxane, there is cycloten.

Although an organic resin film made of an organic resin is formed on the pixel electrode here, an insulator that can be an insulating film may be used.

[0163] As the insulator, an insulating film containing silicon such as silicon oxide, silicon nitride oxide, or silicon nitride is preferably used.

The film thickness (Dc) of the organic resin film 1041 is
0.1 to 2 μm is preferred, and more preferably 0.2 to 2 μm.
The thickness is preferably set to 0.6 μm.

After the organic resin film 1041 is formed, the entire surface of the organic resin film 1041 is etched and the etching is terminated when Dc = 0. When the acrylic resin embedded in the electrode hole remains, the protective portion 1041b is formed. Is done.

Note that dry etching is preferable as the etching method. First, after introducing an etching gas corresponding to an organic resin material to be etched into a vacuum chamber, a high frequency voltage is applied to the electrodes to generate plasma, and the etching gas is decomposed in a plasma atmosphere.

In the etching gas decomposed in the plasma atmosphere, charged particles such as positive ions, negative ions, and electrons and neutral active species are present in different states. When these etching species are adsorbed on the material to be etched, a surface chemical reaction occurs to generate an etching product, and when the etching product is removed, etching is performed.

When an acrylic resin is used as the material of the protective film, it is desirable to use a gas containing oxygen as a main component as an etching gas in the etching.

In this embodiment, an etching gas containing oxygen, helium, and carbon tetrafluoride (CF ₄ ) is used as an etching gas containing oxygen as a main component. Further, as another material, a fluorocarbon-based gas such as dicarbon hexafluoride (C ₂ F ₆ ) may be used.

In these etching gases, it is desirable that oxygen accounts for 60% or more of the whole etching gas.

As shown in this embodiment, an organic resin film is formed on a pixel electrode by a spin coating method, and then this is entirely etched to be protected in an electrode hole 1046 as shown in FIG. Etching is performed in the direction of the arrow so that the portion 1041b is formed. Note that the exposed surface of the protection portion 1041b and the exposed surface of the pixel electrode 1040 formed here are in the same plane as shown in FIG.

Note that the etching rate at this time is determined in advance by checking the etching rate, and the etching is completed when the organic resin film on the pixel electrode 1040 except for the protection portion 1041b has just been removed. Accordingly, the upper surface of the pixel electrode 1040 and the upper surface of the protection unit 1041b become the same flat surface.

When using these organic resins,
The viscosity is preferably set to 10 ⁻³ Pa · s to 10 ⁻¹ Pa · s.

After forming the protection portion 1041b, FIG.
In order to form the EL layer 1042 as shown in FIG.
A film obtained by dissolving the L material in a solvent is formed by spin coating.

After the EL layer 1042 is formed, a cathode 1043 and a protection electrode 1044 are further formed.

With the structure as shown in FIG. 13C as described above, the EL layer 1 is formed at the step of the electrode hole.
The problem of a short circuit between the pixel electrode 1040 and the cathode 1043 that occurs when the substrate 042 is disconnected can be solved.

It should be noted that, as shown in this embodiment, the pixel electrode 1
FIG. 13D is a top view in the case where the protective portion 1041b on the 040 has the same shape as the electrode hole 1046.

The configuration of the present embodiment can be freely combined with the configuration of the first embodiment.

[Embodiment 3] In the embodiment 2, a method of forming a protective film by etching, that is, a so-called etch-back method has been described. However, the etch-back method is not suitable depending on the type of the protective film, and is not flattened. Since there is a limitation that the area that can be formed is several μm to several tens of μm, chemical mechanical polishing (CMP) is performed.
It is also possible to form a protective part using g). Therefore, this embodiment will be described with reference to FIG.

In the present embodiment, FIG.
As shown in (A), the organic resin film 1041 is changed to Dc (>
After the film is formed to a thickness of 0), the polishing material (slurry) is pressed against the organic resin film 1041 with a constant pressure against a polishing pad stretched on a surface plate facing the organic resin film 1041, while rotating the substrate and the surface plate. The protection portion 1041b is formed using so-called CMP, which is flowed and polished until Dc = 0.

The slurry used in performing CMP is obtained by dispersing abrasive particles called abrasive grains in an aqueous solution whose pH has been adjusted, and a different slurry may be used depending on the film to be polished.

In this embodiment, since an acrylic resin is used as the film to be polished, slurries such as silica-based slurry (SiO ₂ ), ceria-based slurry (CeO ₂ ), and fumed silica-based slurry (SiCl ₄ ) are used. Is preferred. However, other slurries include alumina-based slurries (Al ₂ O ₃ ) and zeolite-based slurries, and these may be used.

Further, the potential (zeta potential) between the liquid in the slurry and the abrasive grains (silica particles) affects the processing accuracy, so it is necessary to adjust the pH value by optimizing the pH value.

When polishing using CMP, it is difficult to determine the end point of polishing. If it is polished too much, the pixel electrode will be polished. Therefore,
Forming a film with an extremely slow processing speed to be used as a stopper for CMP, or clarifying the relationship between processing time and processing speed through experiments beforehand, and taking a method of terminating CMP when a certain processing time comes This can prevent unnecessary polishing.

As described above, by using CMP, the protection portion 1041b can be formed irrespective of the thickness and type of the film to be polished.

The structure of this embodiment can be freely combined with the structures of Embodiments 1 and 2.

[Embodiment 4] In this embodiment, the case where the present invention is applied to a passive type (simple matrix type) EL display device will be described with reference to FIG. In FIG. 14, 1
Reference numeral 301 denotes a substrate made of plastic, and 1306 denotes an anode made of a transparent conductive film. Note that the substrate 1301 may be made of a material such as glass or quartz.

In this embodiment, a compound of indium oxide and zinc oxide is formed as a transparent conductive film by an evaporation method.
Although not shown in FIG. 14, a plurality of anodes are arranged in stripes in a direction perpendicular to the plane of the drawing.

The anodes 13 arranged in a stripe pattern
The protection section 1303 of the present invention is formed so as to fill the space between the two. The protection part 1303 is formed along the anode 1302 in a direction perpendicular to the paper surface. Note that the protection portion 1303 in this embodiment may be formed by using the same material by the method described in the first to third embodiments.

Next, an EL made of a polymer organic EL material is used.
A layer 1304 is formed. The same organic EL material as that used in the first embodiment may be used. Since these EL layers are formed along the grooves formed by the protective film 1302, they are arranged in a stripe shape in a direction perpendicular to the paper surface.

Thereafter, although not shown in FIG. 14,
A plurality of cathodes and protective electrodes are arranged in a stripe shape such that a direction parallel to the paper surface is a longitudinal direction and is orthogonal to the anode 1302. In this embodiment, the cathode 1
Reference numeral 305 is made of MgAg, and the protection electrode 1306 is made of an aluminum alloy film, each of which is formed by an evaporation method. In addition, although not shown, wiring is drawn out to a portion where an FPC is attached later so that a predetermined voltage is applied to the protection electrode 1306.

Although not shown here, after forming the protection electrode 1306, a silicon nitride film may be provided as a passivation film.

[0193] As described above, an EL element is formed over the substrate 1301. In this embodiment, since the lower electrode is a light-transmitting anode, the EL layers 1304a to 1304c
Is emitted to the lower surface (substrate 1301). However, the structure of the EL element can be reversed, and the lower electrode can be a light-shielding cathode. In that case, light generated in the EL layer is emitted to the upper surface (the side opposite to the substrate 1301).

Next, a ceramic substrate is prepared as a cover material 1307. In the structure of the present embodiment, a ceramic substrate was used because of its good light-shielding properties.
When the structure of the L element is reversed, the cover material is preferably light-transmitting, so that a substrate made of plastic or glass may be used.

After preparing the cover material 1307 in this way,
A cover material 1307 is attached to the base material 1308 to which barium oxide is added as a desiccant (not shown). After that, the frame member 1310 is attached using the sealing member 1309 made of an ultraviolet curable resin. In this embodiment, a stainless steel material is used as the frame material 1310. Finally, an FPC 1312 is attached via an anisotropic conductive film 1311 to complete a passive EL display device.

The structure of this embodiment can be implemented by freely combining with any of the structures of the first to third embodiments.

[Embodiment 5] When an active matrix type EL display device is manufactured by implementing the present invention, it is effective to use a silicon substrate (silicon wafer) as a substrate. When a silicon substrate is used as a substrate, a switching element or a current control element formed in a pixel portion or a drive element formed in a drive circuit portion is replaced with a conventional IC or LS.
It can be manufactured by using a MOSFET manufacturing technique used for I.

The MOSFET can form a circuit with a very small variation as is proven in ICs and LSIs, and is particularly effective for an analog-driven active matrix EL display device that performs grayscale expression with a current value. It is.

Since the silicon substrate is light-shielding,
It is necessary to have a structure in which light from the EL layer is emitted to the side opposite to the substrate. The EL display device of this embodiment is similar in structure to FIG.
The difference is that a MOSFET is used in place of the TFT forming the pixel 03.

The structure of this embodiment can be implemented by freely combining with any of the structures of Embodiments 1 to 4.

[Embodiment 6] An EL display device formed according to the present invention is of a self-luminous type, so that it has better visibility in a bright place than a liquid crystal display device, and has a wide viewing angle. Therefore, it can be used as a display portion of various electric appliances. For example, to watch a TV broadcast or the like on a large screen, an E of 30 inches or more (typically, 40 inches or more) of diagonal is used.
The EL display device of the present invention may be used as a display unit of an L display (a display in which an EL display device is incorporated in a housing).

The EL display includes all displays for displaying information such as a display for a personal computer, a display for receiving a TV broadcast, and a display for displaying an advertisement. In addition, the EL display device of the present invention can be used as a display portion of various electric appliances.

[0203] Such electric appliances of the present invention include a video camera, a digital camera, a goggle-type display (head-mounted display), a navigation system, a sound reproducing device (car audio, audio component, etc.), a notebook personal computer, and a game. Devices, personal digital assistants (mobile computers, mobile phones,
An image reproducing apparatus provided with a recording medium (specifically, a digital video disc (D
VD) and the like, which reproduces a recording medium and has a display capable of displaying the image. In particular, for a portable information terminal that is often viewed from an oblique direction, it is important to use an EL display device because a wide viewing angle is regarded as important. Specific examples of these electric appliances are shown in FIGS.

FIG. 15A shows an EL display.
A housing 2001, a support base 2002, a display portion 2003, and the like are included. The present invention can be used for the display portion 2003. E
Since the L display is a self-luminous type, it does not require a backlight and can be a display portion thinner than a liquid crystal display.

FIG. 15B shows a video camera, which includes a main body 2101, a display portion 2102, an audio input portion 2103, operation switches 2104, a battery 2105, and an image receiving portion 210.
6 and so on. The EL display device of the present invention can be used for the display portion 2102.

FIG. 15C shows a part (one side on the right) of a head-mounted EL display, which includes a main body 2201, a signal cable 2202, a head-fixing band 2203, and a display unit 2.
204, an optical system 2205, an EL display device 2206, and the like. The present invention can be used for the EL display device 2206.

FIG. 15D shows an image reproducing apparatus (specifically, a DVD reproducing apparatus) provided with a recording medium.
1, recording medium (DVD or the like) 2302, operation switch 23
03, a display unit (a) 2304, a display unit (b) 2305, and the like. The display unit (a) mainly displays image information, and the display unit (b) mainly displays character information. The EL display device of the present invention can be used for these display units (a) and (b). Note that the image reproducing device provided with the recording medium includes a home game machine and the like.

FIG. 15E shows a portable (mobile) computer, which includes a main body 2401, a camera section 2402, an image receiving section 2403, operation switches 2404, a display section 2405, and the like. The EL display device of the present invention can be used for the display portion 2405.

[0209] FIG. 15F illustrates a personal computer, which includes a main body 2501, a housing 2502, a display portion 2503,
A keyboard 2504 and the like are included. The EL display device of the present invention can be used for the display portion 2503.

If the emission luminance of the EL material becomes higher in the future, it becomes possible to enlarge and project the light containing the output image information with a lens or the like and use it for a front-type or rear-type projector.

[0211] Also, the above-mentioned electric appliances are available on the Internet or C
Information distributed through an electronic communication line such as an ATV (cable television) is frequently displayed, and in particular, opportunities to display moving image information are increasing. Since the response speed of the EL material is very high, the EL display device is preferable for displaying a moving image. However, if the outline between pixels is blurred, the entire moving image is also blurred. Therefore, it is extremely effective to use the EL display device of the present invention for clearing the outline between pixels as a display portion of an electronic device.

[0212] In the EL display device, since the light emitting portion consumes power, it is desirable to display information so that the light emitting portion is reduced as much as possible. Therefore, when an EL display device is used for a portable information terminal, particularly a display portion mainly for character information such as a mobile phone or a sound reproducing device, the character information is formed by a light emitting portion with a non-light emitting portion as a background. It is desirable to drive.

FIG. 16A shows a portable telephone, which includes a main body 2601, an audio output unit 2602, and an audio input unit 260.
3, including a display unit 2604, operation switches 2605, and an antenna 2606. The EL display device of the present invention has a display section 260.
4 can be used. Note that the display portion 2604 can display power of the mobile phone by displaying white characters on a black background.

FIG. 16B shows an audio reproducing apparatus, specifically, a car audio system.
702, and operation switches 2703 and 2704. The EL display device of the present invention can be used for the display portion 2702. In this embodiment, the in-vehicle audio is shown, but the present invention may be applied to a portable or home-use audio reproducing apparatus. Note that the display portion 2704 can suppress power consumption by displaying white characters on a black background. This is particularly effective in a portable sound reproducing device.

As described above, the applicable range of the present invention is extremely wide, and the present invention can be used for electric appliances in various fields. In addition, the electric appliance of this embodiment may use the EL display device having any of the configurations shown in the first to fifth embodiments.

[Embodiment 7] EL manufactured using the present invention
In the device, an EL material that can use phosphorescence from triplet excitons for light emission can be used. A light-emitting device using an EL material capable of utilizing phosphorescence for light emission can dramatically improve external light-emitting quantum efficiency. This allows
The power consumption, the life, and the weight of the EL element can be reduced.

Here, a report is shown in which the triplet exciton is used to improve the external emission quantum efficiency. (T.Tsutsui, C.Adachi, S.Saito, Photochemical Proce
sses in Organized Molecular Systems, ed.K. Honda,
(Elsevier Sci. Pub., Tokyo, 1991) p. 437.)

The structural formula of the EL material (coumarin dye) reported in the above article is shown below.

[0219]

Embedded image

(MABaldo, DFO'Brien, Y. You, A. Shou
stikov, S. Sibley, METhompson, SRForrest, Nature
395 (1998) p.151.)

The EL materials (P
The structural formula of (t complex) is shown below.

[0222]

Embedded image

(MABaldo, S. Lamansky, PEBurrrows,
METhompson, SRForrest, Appl.Phys.Lett., 75 (199
9) p.4.) (T.Tsutsui, M.-J.Yang, M.Yahiro, K.Nakamu
ra, T.Watanabe, T.tsuji, Y.Fukuda, T.Wakimoto, S.Ma
yaguchi, Jpn.Appl.Phys., 38 (12B) (1999) L1502.)

The EL materials (I
The structural formula of (r complex) is shown below.

[0225]

Embedded image

As described above, if the phosphorescence emission from the triplet exciton can be used, it is possible in principle to realize an external emission quantum efficiency three to four times higher than the case where the fluorescence emission from the singlet exciton is used. .

The structure of this embodiment can be implemented by freely combining with any of the structures of Embodiments 1 to 6.

[0228]

According to the present invention, it is possible to improve a film formation defect of an electrode hole which occurs when forming an organic EL material. Further, in the present invention, since the method of filling the electrode hole with the protective portion by various methods and shapes is shown, it is possible to form a film according to conditions and applications,
Light emission failure of the EL layer due to a short circuit between the cathode and the anode can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-sectional structure of a pixel portion.

FIG. 2 illustrates a cross-sectional structure of a pixel portion.

FIG. 3 is a diagram showing a top structure and a configuration of a pixel portion.

FIG. 4 is a diagram showing a cross-sectional structure of a pixel portion.

FIG. 5 illustrates a cross-sectional structure of a pixel portion.

FIG. 6 illustrates a manufacturing process of an EL display device.

FIG. 7 illustrates a manufacturing process of an EL display device.

FIG. 8 illustrates a manufacturing process of an EL display device.

FIG. 9 illustrates an element structure of a sampling circuit.

FIG. 10 illustrates an appearance of an EL display device.

FIG. 11 is a diagram showing a circuit block configuration of an EL display device.

FIG. 12 illustrates a cross-sectional structure of an active matrix EL display device.

FIG. 13 illustrates a cross-sectional structure of a pixel portion.

FIG. 14 illustrates a cross-sectional structure of a passive-type EL display device.

FIG. 15 illustrates a specific example of an electric appliance.

FIG. 16 illustrates a specific example of an electric appliance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 33/10 H05B 33/26 Z 33/14 H01L 29/78 612Z 33/26

Claims (34)

[Claims] 1. A self-luminous device comprising a TFT, a pixel electrode electrically connected to the TFT, an EL layer formed on the pixel electrode, and an EL element including a cathode formed on the EL layer. A self-luminous device, wherein a protective portion made of an insulator is provided in an electrode hole. 2. A self-luminous device comprising: a TFT; a pixel electrode electrically connected to the TFT; an EL layer formed on the pixel electrode; and an EL element including a cathode formed on the EL layer. A self-luminous device, wherein a protective portion provided in an electrode hole is sandwiched between the pixel electrode and the EL layer. 3. A self-luminous device comprising: a TFT; a pixel electrode electrically connected to the TFT; an EL layer formed on the pixel electrode; and an EL element including a cathode formed on the EL layer. A self-luminous device having a structure in which a protection portion formed in an electrode hole is made of an insulator, and the EL layer is formed on surfaces of the pixel electrode and the protection portion. 4. A self-luminous device comprising: a TFT; a pixel electrode electrically connected to the TFT; an EL layer formed on the pixel electrode; and an EL element including a cathode formed on the EL layer. A self-luminous device having a structure in which the EL layer and the protection unit are sandwiched between the pixel electrode and the cathode. 5. A self-luminous device comprising a TFT, a pixel electrode electrically connected to the TFT, an EL layer formed on the pixel electrode, and an EL element including a cathode formed on the EL layer. A plurality of the pixel electrodes are formed in a pixel portion, and a protection portion is formed in a gap between the pixel electrodes. 6. The self-luminous device according to claim 1, wherein the surface of the pixel electrode and the surface of the protection unit are uniformly flattened. 7. An electric appliance using the self-luminous device according to any one of claims 1 to 6 as a display unit or a light source. 8. A protection section by forming a TFT on a substrate and a pixel electrode electrically connected to the TFT, forming an insulating film on the pixel electrode, and selectively etching the insulating film. Forming a self-luminous device. 9. A method in which a TFT and a pixel electrode electrically connected to the TFT are formed on a substrate, an organic resin film is formed on the pixel electrode, and the organic resin film is selectively etched. A method for manufacturing a self-luminous device, comprising forming a protective portion. 10. A method of manufacturing a TFT and a pixel electrode electrically connected to the TFT on a substrate, forming an organic resin film on the pixel electrode, and selectively etching the organic resin film. A method for manufacturing a self-luminous device, comprising forming a protective portion in a gap between an electrode hole and a pixel electrode. 11. An insulating film having at least two first electrodes on a substrate, having a gap between the first electrodes, and an insulating film formed in a gap between the first electrodes; And an EL layer formed on the insulating film, and a second electrode formed on the EL layer, wherein the second electrode is provided through the EL layer. A self-luminous device formed on the opposite side of the first electrode. 12. The self-luminous device according to claim 11, wherein said first electrode is an anode and said second electrode is a cathode. 13. The self-luminous device according to claim 11, wherein said self-luminous device is of a passive matrix type. 14. The self-luminous device according to claim 11, wherein said EL layer is made of an organic EL material. 15. A switching element, an interlayer insulating film formed on the switching element, a contact hole opened in the interlayer insulating film, a pixel electrode formed on the interlayer insulating film, and An insulating film formed on an electrode, the pixel electrode, and an EL formed on the insulating film
A self-luminous device having a layer and a second electrode formed on the EL layer, wherein the pixel electrode and the switching element are electrically connected through the contact hole; The self-luminous device, wherein the insulating film is formed on the pixel electrode. 16. The self-luminous device according to claim 15, wherein said switching element comprises a thin film transistor. 17. The self-luminous device according to claim 15, wherein said switching element is formed on a silicon substrate. 18. A self-luminous device according to claim 15, wherein said pixel electrode is an anode, and said second electrode is a cathode. 19. The self-luminous device according to claim 15, wherein said pixel electrode is a cathode and said second electrode is an anode. 20. The self-luminous device according to claim 15, wherein said EL layer comprises at least one kind of organic EL layer. 21. The self-luminous device according to claim 15, wherein the surface of the insulating layer is on the same plane as the pixel electrode. 22. A first switching element, a second switching element, an interlayer insulating film formed on the first switching element and the second switching element, and formed on the interlayer insulating film. A first pixel electrode, a second pixel electrode, an insulating film formed in a gap between the first pixel electrode and the second pixel electrode, the first pixel electrode, the second A self-luminous device including a pixel electrode, an EL layer formed on the insulating film, and a third electrode formed on the EL layer, wherein the first pixel electrode and the second pixel electrode Is the first switching element and the second switching element,
Respectively, and the third electrode is connected to the E
A self-luminous device formed on the opposite side of the first pixel electrode and the second pixel electrode via an L layer. 23. A self-luminous device according to claim 22, wherein said switching element comprises a thin film transistor. 24. The self-luminous device according to claim 22, wherein said switching element is formed on a silicon substrate. 25. A self-luminous device according to claim 22, wherein said pixel electrode is an anode, and said third electrode is a cathode. 26. A self-luminous device according to claim 22, wherein said first and second pixel electrodes are each a cathode, and said third electrode is an anode. 27. A self-luminous device according to claim 22, wherein said EL layer comprises at least one kind of organic EL layer. 28. A self-luminous device according to claim 22, wherein said surface of said insulating layer is flush with said pixel electrode. 29. An electric appliance using the self-luminous device according to claim 11. 30. An electric appliance using the self-luminous device according to claim 15. 31. An electric appliance using the self-luminous device according to claim 22. 32. The electronic device according to claim 29, wherein the electric appliance includes a video camera, a head-mounted EL display, an image reproducing device, a portable computer, a personal computer, a portable telephone, and a sound reproducing device. Electrical appliances. 33. The electronic apparatus according to claim 30, wherein the electric appliance includes a video camera, a head-mounted EL display, an image reproducing device, a portable computer, a personal computer, a mobile phone, and a sound reproducing device. Electrical appliances. 34. The apparatus according to claim 31, wherein the electric appliance includes a video camera, a head-mounted EL display, an image reproducing device, a portable computer, a personal computer, a mobile phone, and a sound reproducing device. Electrical appliances.