JP2013148444A - Terahertz camera and electronic apparatus - Google Patents

Abstract

To provide a terahertz camera and an electronic device capable of improving detection accuracy by making electromagnetic waves not directly incident on an electromagnetic wave absorber contribute to electromagnetic wave detection.
A pyroelectric detector 200 includes a pyroelectric detection element 220, an electromagnetic wave absorber 270, a support member 210, support portions 100 and 104, and a reflector 160. The pyroelectric detection element 220 supported by the support member 210 includes a capacitor 230 whose polarization amount changes based on temperature. The electromagnetic wave absorber 270 covers the top of the pyroelectric detection element and has an area larger than the area of the capacitor in plan view. The reflector 160 is disposed around the pyroelectric detection element, and reflects incident electromagnetic waves toward the electromagnetic wave absorber.
[Selection] Figure 1

Description

  The present invention relates to a terahertz camera and an electronic apparatus.

A terahertz wave is an electromagnetic wave having a wavelength close to infrared. The image measurement technology using terahertz waves has been studied for use in various fields. For example, there are a specific substance detection device using a terahertz camera, determination of counterfeit bills, detection of chemicals in envelopes, non-destructive inspection of buildings, and the like.
On the other hand, as an infrared camera, there is a camera using a pyroelectric detector. The applicant has invented a technique of using a pyroelectric detector in a terahertz camera because the wavelength of the terahertz wave is close to infrared.

  The cell of the pyroelectric detection device has a capacitor including a pyroelectric body connected to an upper electrode and a lower electrode, and various proposals have been made regarding materials of the electrode and the pyroelectric body (Patent Document 1). .

  Capacitors including ferroelectrics connected to the upper and lower electrodes are used in ferroelectric memories, and various proposals have been made regarding electrodes suitable for ferroelectric memories and ferroelectric materials. (Patent Documents 2 and 3). As a bolometer-type detector, Patent Document 4 discloses a structure that absorbs electromagnetic waves.

JP 2008-232896 A JP 2009-71242 A JP 2009-129972 A Japanese Patent No. 3574368

  In both the pyroelectric type and the bolometer type, in the electromagnetic wave detection device, efficiently transferring the heat obtained by efficiently absorbing the incident electromagnetic wave to the detection element leads to an improvement in measurement accuracy. In FIG. 21 and FIG. 22 of Patent Document 4 that discloses a bolometer-type detection device, a reflective film is disposed on the back side of the detection unit including the bolometer thin film via a cavity, and the distance between the detection unit and the reflection film Is λ / 4 (λ is an incident wavelength) to form an optical resonance structure. Moreover, in FIG. 1 etc. of patent document, the flat electromagnetic wave absorption part is provided in the electromagnetic wave incident side rather than the detection part, and the detection part and the electromagnetic wave absorption part are connected with the joining pillar.

  When the technique of Patent Document 4 is applied to a pyroelectric detector, the pyroelectric detection element has a capacitor structure in which a pyroelectric material is sandwiched between two electrodes, so that almost no electromagnetic wave reaches the reflective film on the back side of the capacitor. Rather, it is reflected by the electrode in the capacitor.

  In addition, when the detection unit and the electromagnetic wave absorption unit are connected by a joining column, the vertical connection column hardly contributes to the absorption of the electromagnetic wave and is the only heat transfer path between the electromagnetic wave absorption unit and the detection unit. Since the cross-sectional area of a certain connecting column is small, the heat transfer property is inferior and heat transfer loss occurs. Moreover, electromagnetic waves that are not directly incident on the electromagnetic wave absorbing film cannot contribute to detection.

  In some aspects of the present invention, an electromagnetic wave that is disposed upstream of the pyroelectric detection element in the electromagnetic wave incident direction and that is not directly incident on the electromagnetic wave absorber also contributes to electromagnetic wave detection and can improve detection accuracy. To provide equipment.

A terahertz camera according to one embodiment of the present invention is provided.
A pyroelectric detection element including a first electrode, a second electrode, and a pyroelectric material disposed between the first and second electrodes, and including a capacitor whose polarization amount changes based on temperature;
An electromagnetic wave absorber that covers a top portion of the pyroelectric detection element and projects outward from the top portion of the pyroelectric detection element, is formed in a flat plate shape, and has an area larger than the area of the capacitor in plan view; ,
The pyroelectric detection element includes a first surface and a second surface facing the first surface, the second surface facing the cavity, and the first surface is in contact with the first electrode A support member for mounting
A support part for supporting a part of the second surface of the support member;
A reflector disposed around the pyroelectric detection element and reflecting an incident electromagnetic wave toward the electromagnetic wave absorber;
It is characterized by having.

  According to one aspect of the present invention, when an electromagnetic wave is incident on an electromagnetic wave absorber disposed upstream of the pyroelectric detection element in the electromagnetic wave incident direction, the electromagnetic wave absorber generates heat, and the heat is absorbed by the electromagnetic wave. An electric signal corresponding to the amount of electromagnetic waves transferred from the body to the capacitor and absorbed by the pyroelectric effect can be taken out. The electromagnetic wave that is not directly incident on the electromagnetic wave absorber is also reflected by the reflector disposed around the pyroelectric detection element and is incident on the electromagnetic wave absorber, thereby increasing the amount of absorbed electromagnetic wave. Signal detection accuracy is improved.

  In one aspect of the present invention, the support member includes a mounting portion on which the pyroelectric detection element is mounted, and an arm portion that connects the mounting portion and the support portion. Including a partition part disposed around the mounting part, the reflector can be disposed on the partition part.

  By arranging the partition wall around the mounting portion on which the pyroelectric detection element is mounted, a reflector can be arranged around the pyroelectric detection element and guided to the electromagnetic wave absorber through the reflector. The amount of electromagnetic waves can be increased.

  In one aspect of the present invention, the reflector may include a core member having a slope and a reflective layer coated on the core member. If it carries out like this, since a reflective film can be formed in the slope formed in the core member, a reflective angle can be provided and a reflective film can be formed with a thin film.

  In the terahertz camera according to another aspect of the present invention, the pyroelectric detector described above is one cell, and a plurality of cells can be arranged one-dimensionally along at least one axis direction, or two axes direction, preferably orthogonal two axes Can be two-dimensionally arranged.

  In this case, the partition wall portion is formed in a rectangular ring shape in a plan view, and at least two cells adjacent in the uniaxial direction share one side of the partition wall between the two cells. The reflector formed on one side has a triangular cross-section with the partition wall side as a base, and the electromagnetic wave incident between the two cells is absorbed by the electromagnetic wave in each of the two cells. Can be reflected toward the body. In this way, the cell integration can be increased by sharing one partition by two cells.

It is sectional drawing of the pyroelectric detection apparatus which concerns on one Embodiment of this invention. It is a top view of the pyroelectric detection apparatus shown in FIG. It is sectional drawing which shows the specific structure of a pyroelectric detector, and has shown the cross section containing the wiring to a 2nd electrode (upper electrode). It is a figure different from FIG. 3 of a pyroelectric detector, and has shown the cross section containing a reflector. 5 (A) to 5 (C) are schematic cross-sectional views showing the first half of the manufacturing process of the pyroelectric detector shown in FIG. FIGS. 6A to 6C are schematic cross-sectional views showing the latter half of the manufacturing process of the pyroelectric detector shown in FIG. It is sectional drawing which shows the 1st manufacturing process of the reflector shown in FIG. It is sectional drawing which shows the 2nd manufacturing process of the reflector shown in FIG. It is sectional drawing which shows the 3rd manufacturing process of the reflector shown in FIG. It is sectional drawing which shows the 4th manufacturing process of the reflector shown in FIG. It is a block diagram of the electronic device containing a pyroelectric detector or a pyroelectric detection device. FIGS. 12A and 12B are diagrams showing a configuration example of a pyroelectric detection device in which pyroelectric detectors are two-dimensionally arranged. It is a figure which shows the terahertz camera which concerns on this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not always.

1. Outline of Pyroelectric Detector FIG. 1 is a cross-sectional view of a pyroelectric detector according to this embodiment. FIG. 1 schematically shows electromagnetic wave detectors 10 for two cells adjacent in a uniaxial direction. ing. In FIG. 1, each of the electromagnetic wave detectors 10 for two cells has a support part 100 as a base part in common. A post (a part of the support portion in a broad sense) 104 that supports the support member 210 spanned on the cavity portion 102 is formed on the base portion (support portion) 100 so as to protrude. Each of the electromagnetic wave detectors 10 for two cells has a pyroelectric detection element 220 including a capacitor 230 (see FIG. 3) mounted on a support member 210.

  Each of the two-cell electromagnetic wave detectors 10 covers the top of the pyroelectric detection element 220 and projects outward from the top of the pyroelectric detection element 220, and is formed in a flat plate shape. An electromagnetic wave absorber 270 having an area larger than the area is provided. In FIG. 1, the electromagnetic wave absorber 270 is connected to the top of the pyroelectric detection element 220 via the joint column 272. However, the electromagnetic wave absorber 270 can be directly fixed to the top of the pyroelectric detection element 220 instead of the joining column portion 272 (see FIG. 3).

  A reflector 160 that reflects incident electromagnetic waves toward the electromagnetic wave absorber 270 is provided around the pyroelectric detection elements 220 for two cells. The reflector 160 has a triangular cross section with the post 104 side as a base.

  As shown in FIG. 1, an electromagnetic wave that is not directly incident on the electromagnetic wave absorber 270 but is incident between the cells can be incident on the reflector 160. The incident electromagnetic wave is reflected by the reflector 160, guided to the back side of the electromagnetic wave absorber 270, and absorbed by the electromagnetic wave absorber 270. Therefore, in addition to the electromagnetic wave incident from the front surface side of the electromagnetic wave absorber 270, the electromagnetic wave incident from the back surface side of the electromagnetic wave absorber 270 is increased, so that the signal component is increased and the detection accuracy is improved.

  In addition, since the reflector 160 having a triangular longitudinal section does not erroneously induce electromagnetic waves across the cells, crosstalk between the cells is prevented.

  FIG. 2 is a plan view of the pyroelectric detection device of FIG. 1, and the right cell is drawn with the electromagnetic wave absorber 270 removed. In FIG. 2, the area occupied by the pyroelectric detector 200 for one cell is, for example, a rectangle with a side of several tens of μm. The area occupied by the pyroelectric detection element 220 for one cell is, for example, a rectangle having a side length of about 10 μm.

  The post 104 shown in FIG. 1 is formed as a rectangular ring-shaped partition wall in a plan view that is continuous around each of the two cells in the plan view shown in FIG.

  As shown in the left cell of FIG. 2, the support member 210 that supports the pyroelectric detection element 220 includes a mounting portion 210 </ b> A for mounting the pyroelectric detection element 220, and connects the mounting portion 210 </ b> A to the post 104, for example, 2 Arm 210B. An opening 102A communicating with the cavity shown in FIG. 1 is formed between the support member 210 and the partition post 104 in plan view.

  The pyroelectric detection element 220 includes a capacitor 230 (see FIG. 3) described later, and has a pyroelectric material 234 between a first electrode (lower electrode) 234 and a second electrode (upper electrode) 236. Therefore, as shown in FIG. 2, the wiring layer 222 connected to the first electrode (lower electrode) 234 and the wiring layer 224 connected to the second electrode (upper electrode) 236 include a pyroelectric detection element. 220. Both of the wiring layers 222 and 224 are connected to a drive circuit built in the base portion 100 through a plug 106 formed on the post 104.

  Therefore, as shown in FIG. 2, the partition-like post 104 can be provided with the above-described reflector 160 except for the region where the plug 106 is formed, for example. Note that it is possible to form the reflector 160 on the region where the plug 106 is formed, so that the reflector 160 can be disposed on the entire circumference of the pyroelectric detector 200 of one cell. Or you may provide the post which arrange | positions the reflector 160 in the perimeter of the pyroelectric detector 200 separately from the post in which the plug 106 is formed.

  In FIG. 2, the partition-like post 104 is formed in a rectangular ring shape in plan view, and two cells adjacent in one axis direction share one side of the partition-like post 104 positioned between the two cells. . In this case, as shown in FIG. 2, on one side of the shared post 104, two plugs 106 for wirings 222 and 224 connected to two adjacent cells across the one side are formed. Thereby, since it is not necessary to arrange two posts 104 dedicated to each cell between two adjacent cells, the cell integration density can be increased. A plurality of cells can be two-dimensionally arranged along two axes, for example, orthogonal two-axis directions. In that case, each of the two cells adjacent in the biaxial direction can share one side of the partition-like post 104 positioned between the two cells.

2. Specific Structure of Pyroelectric Detector FIG. 3 is a cross-sectional view of the pyroelectric detector 200 shown in FIGS. 1 and 2 and shows a cross section at a position including the wiring layers 222 and 224. FIG. 4 is a cross-sectional view of the pyroelectric detector 200 at a position different from that in FIG. 3, and shows a cross section at a position including the reflector 160. In the pyroelectric detector 200 during the manufacturing process, the cavity 102 shown in FIGS. 3 and 4 is buried with the first sacrificial layer 150 (see FIG. 5A). The first sacrificial layer 150 exists from before the formation process of the support member 210 and the pyroelectric detection element 220 to after the formation process, and is removed by isotropic etching after the formation process of the pyroelectric detection element 220. Is.

As shown in FIGS. 3 and 4, the base (supporting portion) 100 includes a substrate such as a silicon substrate 110 and a spacer layer 120 formed of an insulating film (such as SiO ₂ ) on the silicon substrate 110. . The post (supporting portion) 104 shown in FIGS. 1 and 2 is formed by etching the spacer layer 120, and is made of, for example, SiO ₂ . A plug 106 (see FIG. 2) connected to the first and second electrode wiring layers 222 and 224 can be disposed on the post (support portion) 104. The plug 106 is connected to a row selection circuit (row driver) provided on the silicon substrate 110 or a readout circuit that reads data from the detector through a column line. The cavity 102 is formed simultaneously with the post 104 by isotropic etching of the first sacrificial layer 150 (see FIG. 6B and the like) in the spacer layer 120. The opening 102A shown in FIG. 2 is formed by pattern-etching the support member 210. Further, an etchant is supplied from the opening 102aA shown in FIG. 2, and the first sacrificial layer 150 (see FIG. 6B and the like) is isotropically etched. Due to this etching, etching stop films 130 and 140 remain on the exposed surface of the cavity 102 as shown in FIG.

The pyroelectric detection element 220 mounted on the first surface 211 </ b> A of the support member 210 includes a capacitor 230. The capacitor 230 includes a pyroelectric body 232, a first electrode (lower electrode) 234 connected to the lower surface of the pyroelectric body 232, and a second electrode (upper electrode) 236 connected to the upper surface of the pyroelectric body 232. Contains. The first electrode 234 can include, for example, an adhesion layer that improves adhesion between the support member 210 formed of a plurality of layers and a first layer member (for example, SiO ₂ that is an insulating layer). The second surface 211B of the support member 210 faces the cavity 102.

  The capacitor 230 is covered with a first reducing gas barrier layer 240 that suppresses a reducing gas (hydrogen, water vapor, OH group, methyl group, etc.) from entering the capacitor 230 in a step after the formation of the capacitor 230. This is because the pyroelectric body (such as PZT) 232 of the capacitor 230 is an oxide, and when the oxide is reduced, oxygen vacancies are generated and the pyroelectric effect is impaired.

The first reducing gas barrier layer 240 may include a first barrier layer in contact with the capacitor 230 and a second barrier layer stacked on the first barrier layer. The first barrier layer can be formed, for example, by depositing aluminum oxide Al ₂ O ₃ by sputtering. Since no reducing gas is used in the sputtering method, the capacitor 230 is not reduced. The second hydrogen barrier layer can be formed, for example, by depositing aluminum oxide Al ₂ O ₃ by, for example, an atomic layer chemical vapor deposition (ALCVD) method. A normal CVD (Chemical Vapor Deposition) method uses a reducing gas, but the capacitor 230 is isolated from the reducing gas by the first barrier layer.

Here, the total film thickness of the first reducing gas barrier layer 240 is 50 to 70 nm, for example, 60 nm. At this time, the film thickness of the first barrier layer formed by the CVD method is thicker than the second barrier layer formed by the atomic layer chemical vapor deposition (ALCVD) method, and is 35 to 65 nm, for example, 40 nm even if it is thin. In contrast, the thickness of the second barrier layer formed by atomic layer chemical vapor deposition (ALCVD) can be reduced, for example, by forming aluminum oxide Al ₂ O ₃ at a thickness of 5 to 30 nm, for example, 20 nm. The The atomic layer chemical vapor deposition (ALCVD) method has excellent embedding characteristics as compared with the sputtering method and the like, so it can cope with miniaturization, and the first and second barriers have a reducing gas barrier property. Can be increased. In addition, the first barrier layer formed by sputtering is not dense compared to the second barrier layer, but it is effective in reducing the heat transfer rate, so that the heat dissipation from the capacitor 230 is reduced. Can be prevented.

  An interlayer insulating film 250 is formed on the first reducing gas barrier layer 240. In general, when the source gas (TEOS) of the interlayer insulating film 250 chemically reacts, a reducing gas such as hydrogen gas or water vapor is generated. The first reducing gas barrier layer 240 provided around the capacitor 230 protects the capacitor 230 from the reducing gas generated during the formation of the interlayer insulating film 250. The first reducing gas barrier layer 240 and the interlayer insulating film 250 can be called protective films that protect the capacitor 230. Alternatively, when the interlayer insulating film 250 is called a protective film that protects the capacitor 230, the first reducing gas barrier layer 240 can be interposed between the protective film 250 and the capacitor 230.

  As shown in FIG. 3, on the interlayer insulating film 250, the first electrode (lower electrode) wiring layer 222 and the second electrode (upper electrode) wiring layer 224 shown in FIG. A first contact hole 252 and a second contact hole 254 are formed in the interlayer insulating film 250 in advance before the electrode wiring is formed. At that time, a contact hole is similarly formed in the first reducing gas barrier layer 240. The first electrode (lower electrode) 234 and the first electrode wiring layer 222 are electrically connected by the first plug 226 embedded in the first contact hole 252. Similarly, the second electrode (upper electrode) 236 and the second electrode wiring layer 224 are electrically connected by the second plug 228 embedded in the second contact hole 254.

  Here, when the interlayer insulating film 250 does not exist, when the first electrode (lower electrode) wiring layer 222 and the second electrode (upper electrode) wiring layer 224 are subjected to pattern etching, the lower layer of the first reducing gas barrier layer 240 is formed. The second barrier layer is etched and the barrier property is lowered. The interlayer insulating film 250 is necessary for ensuring the barrier property of the first reducing gas barrier layer 240.

  The interlayer insulating film 250 preferably has a low hydrogen content. Therefore, the interlayer insulating film 250 is degassed by annealing.

  Note that the first reducing gas barrier layer 240 on the top surface of the capacitor 230 is closed without the second contact hole 254 when the interlayer insulating film 250 is formed, so that the reducing gas in the formation of the interlayer insulating film 250 enters the capacitor 230. Never do. However, the barrier property deteriorates after the second contact hole 254 is formed in the first reducing gas barrier layer 240. As an example for preventing this, the second plug 228 may include a barrier metal layer. The barrier metal layer is not preferably a highly diffusive material such as titanium Ti, and titanium / aluminum / nitride TiAlN having a low diffusibility and a high reducing gas barrier property can be employed.

As shown in FIGS. 3 and 4, a second reducing gas barrier layer 260 may be provided to cover the interlayer insulating film 250 and the first and second electrode wiring layers 222 and 224. The second reducing gas barrier layer 260 is a second sacrificial layer 280 embedded in the lower layer of the undercut electromagnetic wave absorbing film (270) in the process of manufacturing the electromagnetic wave absorber 270 (see FIG. 6B, etc.). It also functions as an etching stop film when isotropically etched. The second reducing gas barrier layer 260 is formed, for example, by depositing aluminum oxide Al ₂ O ₃ to a thickness of 20 to 50 nm by atomic layer chemical vapor deposition (ALCVD).

  When the second sacrificial layer 280 shown in FIG. 6B or the like is isotropically etched in a reducing atmosphere with hydrofluoric acid or the like, the second reducing gas barrier layer 260 has a reducing gas in the capacitor 230 together with the first reducing gas barrier layer 240. Intrusion can be suppressed.

As shown in FIGS. 3 and 4, the electromagnetic wave absorber 270 is disposed upstream of the pyroelectric detection element 220 in the electromagnetic wave incident direction. The electromagnetic wave absorber 270 is made of a material that generates heat according to the amount of absorbed electromagnetic waves, and is made of, for example, SiO ₂ or SiN. The heat collected by absorbing the electromagnetic wave is transferred from the electromagnetic wave absorber 270 to the pyroelectric body 232, so that the amount of spontaneous polarization of the capacitor 230 is changed by the heat, and the electromagnetic wave is detected by detecting the charge due to the spontaneous polarization. Can be detected.

  The electromagnetic wave absorber 270 is connected to the second electrode (upper electrode) 236 located at the top of the pyroelectric detection element 220 so as to cover the top of the pyroelectric detection element 220 and It protrudes outward from the top and is formed in a flat plate shape, and has an area larger than the area of the capacitor 230 (in this embodiment, the area of the first electrode 232 having the maximum area) in plan view. As shown in FIG. 2, when one cell pyroelectric detector 200 is arranged along one axis as shown in FIG. 2, the electromagnetic wave absorber 270 does not exceed the area occupied by one cell region, and between the cells. Are set to be substantially equal.

In the present embodiment, the electromagnetic wave absorber 270 is connected to the second electrode (upper electrode) 236 via the second plug 228 and the wiring layer 224A. 3 and 4, an etching stop film (for example, aluminum oxide) necessary for isotropic etching of a second sacrificial layer 280 (see FIG. 6B), which will be described later, is formed on the lower surface of the electromagnetic wave absorber 270. Al ₂ O ₃ film) 290 remains. In this case, the etching stop film 290 is also interposed between the electromagnetic wave absorber 270 and the wiring layer 224A. However, if the material of the electromagnetic wave absorber 270 has a small selection ratio with respect to the etchant that etches the second sacrificial layer 280, the etching stop film 290 is not necessary. Note that the etching stop film 290 can be a highly conductive metal film. Furthermore, if the metal film 290 is formed to a predetermined thickness, the metal film 290 functions as a support layer for the electromagnetic wave absorber 270 and can increase the rigidity of the electromagnetic wave absorber 270 and also function as an electromagnetic wave reflection film. You can also. In FIG. 4, an etching stop film (for example, an aluminum oxide Al ₂ O ₃ film) 292 is formed on the surface facing the opening 102A formed after pattern etching of the support member 210.

  Here, generally, when the second plug 228 is used only for electrical contact between the wiring layer 224 and the second electrode, the second contact hole 254 is formed with a relatively small diameter. However, in the present embodiment, the second plug 228 places top priority on conductivity as well as heat conductivity. For this reason, the second plug 228 needs to have heat conductivity. Therefore, the second plug 228 is in contact with a region of 50% or more, preferably 60%, more preferably 80% or more of the area of the second electrode 236 in plan view. Thus, the second plug 228 is ensured with conductivity as well as heat conductivity.

  Further, as shown in FIG. 4, a reflector 160 is formed on the post 104. The reflector 160 can include, for example, a core member 162 having a triangular cross section and a reflective film 164 formed on the surface of the core member. Therefore, as shown in FIG. 1, an electromagnetic wave that is not directly incident on the electromagnetic wave absorber 270 can be reflected and incident from the back side of the electromagnetic wave absorber 270.

  According to the infrared detector 200 of the present embodiment, the electromagnetic wave absorber 270 having an area larger than the area of the capacitor 230 in a plan view is provided upstream of the pyroelectric detection element 220 in the electromagnetic wave incident direction. In addition, since the reflector 160 is provided in the periphery thereof, the incident electromagnetic wave can be efficiently converted into heat by the pyroelectric detector 200 of each cell. In addition, since the electromagnetic wave absorber 270 is supported at the top of the pyroelectric detection element 220, the joining column 272 shown in FIG. 1 and Patent Document 4 is not required, and the support is stabilized and the heat transfer area is expanded. .

  Since the electromagnetic wave absorber 270 is connected to the second electrode (upper electrode) 236 of the capacitor 230 through the second plug 228 having heat conductivity, the heat collected by absorbing the electromagnetic wave is absorbed by the electromagnetic wave. Heat can be efficiently transferred from the body 270 to the capacitor 230 via the heat conductive second plug 228. Thus, the signal intensity based on the electromagnetic wave detection can be increased and the electromagnetic wave detection accuracy can be improved.

  Moreover, the thickness of the electromagnetic wave absorber 270 can be set to (2m + 1) λ / 4 (m = 0, 1, 2,...) With respect to the wavelength λ of the incident electromagnetic wave. In this way, the electromagnetic wave that has not been absorbed by the electromagnetic wave absorber 270 is an optical resonant structure in which the wiring layer 224A or the metal support layer 290 is the lower reflective layer, and the uppermost surface (interface) of the electromagnetic wave absorber 270 is the upper reflective layer. Resonated at. Thereby, the electromagnetic wave absorption efficiency in the electromagnetic wave absorber 270 can be increased.

3. Next, the manufacturing method of the pyroelectric detector 200 will be described with reference to FIGS. 5 (A) to 5 (C), FIGS. 6 (A) to 6 (C), and FIGS. This will be described with reference to FIG.

3.1. Method for Manufacturing Pyroelectric Detector Including Electromagnetic Wave Absorber First, a method for manufacturing a pyroelectric detector 200 including an electromagnetic wave absorber 270 will be described with reference to FIGS. 5 (A) to 5 (C) and FIGS. 6 (A) to 6 (A). This will be described with reference to FIG. As shown in FIG. 5A, the first sacrificial layer 150 is buried in a region to be the cavity 102 in the finished product of FIG. 1, and an etching stop film 140 is formed on the first sacrificial layer 150. The support member 210 and the pyroelectric detection element 220 are formed on the first sacrificial layer 150 and the etching stop film 140 thereon. In this state, the support member 210 is not patterned and is formed on the entire surface.

  In FIG. 5A, on the etching stop film 140, the support member 210, the capacitor 230, the first reducing gas barrier layer 240, the interlayer insulating film 250, the first and second contact holes 252 and 254, the first and second plugs. 226 and 228 and wiring layers 222 and 224 are formed.

Next, as shown in FIG. 5B, the entire surface exposed on the support member 210 in the state of FIG. 5A is covered and an etching stop film (for example, an aluminum oxide Al ₂ O ₃ film) is covered. The second reducing gas barrier layer 260 that functions also as an atomic layer chemical vapor deposition (ALCVD) method, for example. In addition, the manufacturing process of the reflector 160 mentioned later is implemented following the process of FIG.5 (B), for example. Here, the manufacturing process of the electromagnetic wave absorber 270 performed after the manufacturing process of the reflector 160 will be described.

As shown in FIG. 5C, a second sacrificial layer (eg, SiO ₂ ) 280 is formed on the entire surface by, for example, a CVD method so as to cover the second reducing gas barrier layer 260. At this time, the second sacrificial layer 280 is formed along the unevenness of the underlayer.

  Next, as shown in FIG. 6A, the second sacrificial layer 280 is planarized by, for example, CMP, so that the second sacrificial layer 280 and the top wiring layer 224A are flush with each other. As a result, a plane for forming the electromagnetic wave absorber 270 is formed. In FIG. 6A, the second plug 228 and a part of the second reducing gas barrier layer 260 on the wiring layer 224A are also etched, and the wiring layer 224A is exposed on the top surface.

Next, as shown in FIG. 6B, an etching stop film (for example, an aluminum oxide Al ₂ O ₃ film or a metal film) 290 is formed on the entire surface by, eg, atomic layer chemical vapor deposition (ALCVD). An electromagnetic wave absorber (for example, SiO ₂ film or SiN film) 270 is formed thereon by CVD or the like. Thereafter, the etching stop film 290 and the electromagnetic wave absorber 270 are patterned by photolithography. Thereby, in each cell, the electromagnetic wave absorber 270 having an area larger than the area of the capacitor 230 in a plan view is formed by patterning.

  Thereafter, as shown in FIG. 6C, the second sacrificial layer 280 is removed by isotropic etching using, for example, hydrofluoric acid. At this time, the electromagnetic wave absorber 270 is protected by the etching stop film 290, and the pyroelectric detection element 220 is also protected by the etching stop film (second reducing gas barrier layer) 260. Note that an etching stop film is also preferably formed on the side surface of the electromagnetic wave absorber 270. As a result, the lower surface of the electromagnetic wave absorber 270 becomes a non-contact surface except for the surface in contact with the top of the pyroelectric detection element 220 and is thermally separated into an undercut shape. As described above, since the electromagnetic wave absorber 270 has a non-contact surface except for the surface in contact with the top of the pyroelectric detection element 220, the collected heat is transferred to the capacitor 230 by solid heat conduction.

  Thereafter, the support member 210 is patterned, and the first sacrificial layer 150 under the support member 210 is removed by isotropic etching using hydrofluoric acid or the like using the opening 102A (see FIG. 2) formed thereby. Thus, the pyroelectric detector 200 shown in FIG. 1 is completed.

3.2. Reflector Manufacturing Method An example of a reflector manufacturing method will be described with reference to FIGS. The manufacturing method of the reflector 160 shown in FIGS. 7 to 10 is performed, for example, between FIGS. 5 (B) to 5 (C). As shown in FIG. 7, a third sacrificial layer 300 is formed and planarized on the entire surface covered with the first and second reducing gas barrier layers (etching stop films) 240 and 260. Further, a trench etching mask 302 is formed on the third sacrificial layer 300.

  FIG. 8 shows a core member 162 having a triangular longitudinal section formed when the third sacrificial layer 300 is etched using the mask 302 shown in FIG. Since the edge of the ring-shaped hole 304 formed in the mask 302 recedes as the etching progresses, the triangular core member 162 can be formed in accordance with the relationship between the shape of the mask hole 304 and the etching rate.

  Next, as shown in FIG. 9, a metal film (reflective film) 310 is formed on the third sacrificial layer 300 and the reflector 160 by, for example, sputtering, and the metal film 310 is patterned to reflect on the core member 162. The reflector 160 on which the film 164 is formed is completed.

4). Electronic Device FIG. 11 shows a configuration example of an electronic device including the pyroelectric detector of the present embodiment. The electronic apparatus includes an optical system 400, a sensor device (pyroelectric detection device) 410, an image processing unit 420, a processing unit 430, a storage unit 440, an operation unit 450, and a display unit 460. Note that the electronic apparatus of the present embodiment is not limited to the configuration in FIG. 11, and some of the components (for example, the optical system, the operation unit, the display unit, etc.) are omitted, or other components are added. Various modifications of the above are possible.

  The optical system 400 includes, for example, one or a plurality of lenses and a driving unit that drives these lenses. Then, an object image is formed on the sensor device 410. If necessary, focus adjustment is also performed.

  The sensor device 410 is configured by two-dimensionally arranging the pyroelectric detectors 200A (200B, 200C) of the present embodiment described above, and includes a plurality of row lines (word lines, scanning lines) and a plurality of column lines (data lines). ) Is provided. The sensor device 410 includes a row selection circuit (row driver), a readout circuit that reads data from the detector via a column line, an A / D conversion unit, and the like, in addition to the two-dimensionally arranged detectors. Can do. By sequentially reading data from each detector arranged two-dimensionally, it is possible to perform imaging processing of an object image.

  The image processing unit 420 performs various image processing such as image correction processing based on digital image data (pixel data) from the sensor device 410.

  The processing unit 430 controls the entire electronic device or controls each block in the electronic device. The processing unit 430 is realized by a CPU or the like, for example. The storage unit 440 stores various types of information, and functions as a work area for the processing unit 430 and the image processing unit 420, for example. The operation unit 450 serves as an interface for the user to operate the electronic device, and is realized by, for example, various buttons or a GUI (Graphical User Interface) screen. The display unit 460 displays, for example, an image acquired by the sensor device 410, a GUI screen, and the like, and is realized by various displays such as a liquid crystal display and an organic EL display.

  As described above, the sensor device 410 is configured by using the pyroelectric detector for one cell as a sensor and arranging the pyroelectric detector for one cell in two dimensions, for example, in two orthogonal directions. In this way, a heat distribution image resulting from electromagnetic waves can be provided. Using this sensor device 410, an electronic device using a terahertz camera such as a specific substance detection device, determination of a counterfeit bill, detection of medicine in an envelope, and nondestructive inspection of a building can be configured.

  FIG. 12A shows a configuration example of the sensor device 410 of FIG. The sensor device includes a sensor array 500, a row selection circuit (row driver) 510, and a readout circuit 520. An A / D converter 530 and a control circuit 550 can be included. By using this sensor device, a high-performance terahertz camera can be realized.

  In the sensor array 500, for example, as shown in FIG. 2, a plurality of sensor cells are arranged (arranged) in the biaxial direction. A plurality of row lines (word lines, scanning lines) and a plurality of column lines (data lines) are provided. One of the row lines and the column lines may be one. For example, when there is one row line, a plurality of sensor cells are arranged in a direction (lateral direction) along the row line in FIG. On the other hand, when there is one column line, a plurality of sensor cells are arranged in a direction (vertical direction) along the column line.

  As shown in FIG. 12B, each sensor cell of the sensor array 500 is arranged (formed) at a location corresponding to the intersection position of each row line and each column line. For example, the sensor cell of FIG. 12B is disposed at a location corresponding to the intersection position of the row line WL1 and the column line DL1. The same applies to other sensor cells.

  The row selection circuit 510 is connected to one or more row lines. Then, each row line is selected. For example, when a sensor array 500 (focal plane array) of QVGA (320 × 240 pixels) as shown in FIG. 12B is taken as an example, row lines WL0, WL1, WL2,... WL239 are sequentially selected (scanned). Perform the action. That is, a signal (word selection signal) for selecting these row lines is output to the sensor array 500.

  The read circuit 520 is connected to one or more column lines. Then, a read operation for each column line is performed. Taking the QVGA sensor array 500 as an example, an operation of reading detection signals (detection current, detection charge) from the column lines DL0, DL1, DL2,.

  The A / D conversion unit 530 performs a process of A / D converting the detection voltage (measurement voltage, ultimate voltage) acquired in the reading circuit 520 into digital data. Then, the digital data DOUT after A / D conversion is output. Specifically, the A / D converter 530 is provided with each A / D converter corresponding to each of the plurality of column lines. Each A / D converter performs A / D conversion processing of the detection voltage acquired by the reading circuit 520 in the corresponding column line. Note that one A / D converter is provided corresponding to a plurality of column lines, and the detection voltage of the plurality of column lines can be A / D converted in a time division manner using this one A / D converter. Good.

  The control circuit 550 (timing generation circuit) generates various control signals and outputs them to the row selection circuit 510, the read circuit 520, and the A / D conversion unit 530. For example, a charge or discharge (reset) control signal is generated and output. Alternatively, a signal for controlling the timing of each circuit is generated and output.

  FIG. 13 shows an example of a terahertz camera including the pyroelectric detector of the present embodiment. The electromagnetic wave absorbing material of the above-described sensor device 410 is set so that the absorption wavelength is optimized by the terahertz wave, and an example in which the terahertz camera 1000 is configured in combination with the terahertz light irradiation unit is shown.

  The terahertz camera 1000 includes a control unit 1010, an irradiation light unit 1020, an optical filter 1030, an imaging unit 1040, and a display unit 1050. The imaging unit 1040 includes an optical system such as a lens (not shown) and a sensor device that optimizes the absorption wavelength of the electromagnetic wave absorber of the pyroelectric detector described above in the terahertz range.

  The control unit 1010 includes a system controller that controls the entire apparatus, and the system controller controls the light source driving unit and the image processing unit included in the control unit. The irradiation light unit 1020 includes a laser device that emits terahertz light (an electromagnetic wave having a wavelength in the range of 100 μm to 1000 μm) and an optical system, and irradiates the person 1060 to be inspected with terahertz light. The reflected terahertz light from the person 1060 is received by the imaging unit 1040 through the optical filter 1030 that allows only the spectral spectrum of the specific substance 1070 to be detected to pass. The image signal generated by the imaging unit 1040 is subjected to predetermined image processing by the image processing unit of the control unit 1010, and the image signal is output to the display unit 1050. The presence of the specific substance 1070 can be determined because the intensity of the received light signal varies depending on whether or not the specific substance 1070 is present in the clothes of the person 1060.

  Although several embodiments have been described above, it is easily understood by those skilled in the art that many modifications can be made without substantially departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, a term described at least once together with a different term having a broader meaning or the same meaning in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings.

  The present invention can be widely applied to various pyroelectric detectors. Note that the wavelength of the electromagnetic wave to be detected is an effective technique particularly when the wavelength is a terahertz wave.

  100 base (support), 102 cavity, 104 support (post), 130, 140 etching stop film, 150 first sacrificial layer, 160 reflector, 162 core member, 164 reflection film, 200 pyroelectric detector, 210 Support member, 211A 1st surface, 211B 2nd surface, 220 detection element, 222,224 1st, 2nd electrode wiring layer, 226,228 1st, 2nd plug, 230 capacitor, 232 pyroelectric body, 234 1st 1 electrode, 236 2nd electrode, 240 1st reducing gas barrier layer, 250 interlayer insulating film (protective film), 260 2nd reducing gas barrier layer, 270 electromagnetic wave absorber, 280 2nd sacrificial layer, 290 etching stop film (support layer, Reflective film), 292 etching stop film, 300 third sacrificial layer, 302 mask, 304 mask hole, 310 Reflection film (metal layer), 1000 terahertz camera, 1020 irradiated light unit, 1040 an imaging unit.

Claims (7)

A pyroelectric detection element including a first electrode, a second electrode, and a pyroelectric material disposed between the first and second electrodes, and including a capacitor whose polarization amount changes based on temperature;
An electromagnetic wave absorber that covers a top portion of the pyroelectric detection element and is formed in a flat plate shape and projects outward from the top portion of the pyroelectric detection element, and has an area larger than the area of the capacitor in plan view; ,
The pyroelectric detection element includes a first surface and a second surface facing the first surface, the second surface facing the cavity, and the first surface is in contact with the first electrode A support member for mounting
A support part for supporting a part of the second surface of the support member;
A terahertz camera comprising: a reflector disposed around the pyroelectric detection element and reflecting an incident electromagnetic wave toward the electromagnetic wave absorber. In claim 1,
The support member includes a mounting portion on which the pyroelectric detection element is mounted, and an arm portion that connects the mounting portion and the support portion,
The support part includes a partition part disposed around the mounting part,
The terahertz camera, wherein the reflector is disposed on the partition wall. In claim 1 or 2,
The terahertz camera, wherein the reflector includes a core member having a slope and a reflective layer covered with the core member.   A terahertz camera, wherein the pyroelectric detector according to any one of claims 1 to 3 is one cell, and a plurality of cells are arranged along at least one axis direction. The terahertz camera according to claim 2 is a cell, and a pyroelectric detection device in which a plurality of cells are arranged along at least one axis direction,
The partition wall is formed in a rectangular ring shape in plan view, and the two cells adjacent in at least one axial direction share one side of the partition located between the two cells,
The reflector formed on one side of the partition wall has a triangular cross section with the partition wall side as a base, and electromagnetic waves incident between the two cells are transmitted to each of the two cells. A terahertz camera, which is reflected toward the electromagnetic wave absorber.   An electronic apparatus comprising the terahertz camera according to claim 1.   An electronic apparatus comprising the terahertz camera according to claim 4.

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