JP2013044590A - Thermal type photo-detector, thermal type photo-detecting device, electronic apparatus and thermal type photo-detector manufacturing method - Google Patents

Abstract

A thermal detector capable of setting a wide wavelength band to be measured is provided.
SOLUTION: A silicon substrate 10, a spacer member 20 formed on the silicon substrate 10 and having a recess 30, a support member 40 facing the recess 30 of the spacer member 20 and supported by the spacer member 20, and on the support member 40 And a pyroelectric infrared detection element 60 that detects heat, and the recess 30 has a first plane 31 formed in a direction intersecting the thickness direction of the spacer member 20 on the bottom surface, and the bottom surface and the support. And a reflective film 36 that reflects light to the first plane 31 and the second plane 32, between the member 40 and the second plane 32 formed in a direction intersecting the thickness direction of the spacer member 20. Is formed.
[Selection] Figure 2

Description

  The present invention relates to a thermal detector, a thermal detector, an electronic device, and a method for manufacturing a thermal detector.

  A thermal detector is known as an optical sensor. The thermal detector converts light emitted from an object into heat and measures a change in temperature with a heat detection element. Thermal detectors include a thermopile that directly detects a temperature rise accompanying light absorption, a pyroelectric element that detects a change in electrical polarization, and a bolometer that detects a temperature rise as a resistance change. In recent years, attempts have been made to manufacture smaller thermal detectors using semiconductor manufacturing technology (MEMS manufacturing technology, etc.).

  In the infrared detection element described in Patent Document 1, a membrane (support member) is formed on a cavity, and the membrane is provided with an infrared absorption layer, a high thermal conduction layer, and an infrared detection unit. This cavity is provided for thermal isolation between the element and the substrate.

Japanese Patent Laid-Open No. 9-133578

In the structure of the above-mentioned Patent Document 1, it is possible to adopt a structure in which the infrared light transmitted through the membrane is reflected at the bottom surface of the cavity to cause optical resonance with the membrane, and the infrared light is absorbed by the membrane to improve efficiency. It is. The wavelength of infrared light that optically resonates depends on the depth of the cavity.
However, the conventional thermal detector can only use the optical resonance of the wavelength corresponding to the depth of one kind of cavity, and has a problem that the wavelength band to be measured cannot be set widely.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A thermal detector according to this application example includes a substrate, a spacer member formed on the substrate and having a recess, and a support member that faces the recess of the spacer member and is supported by the spacer member And a heat detecting element formed on the support member for detecting heat, wherein the recess is formed on the bottom surface in a direction intersecting the thickness direction of the spacer member, and the bottom surface And a second plane formed in a direction intersecting with the thickness direction of the spacer member, and a reflective film that reflects light on the first plane and the second plane. It is formed.

According to this structure, the 1st plane and the 2nd plane are provided in the recessed part (cavity part) of the spacer member. And the light of a different wavelength reflected on the 1st plane and the 2nd plane can be absorbed with a support member.
Thus, the thermal detector of this application example can capture a wide range of wavelengths of light and set a wide wavelength band for measurement.
Here, the expression “˜up” in “on the substrate” and “on the support member” may be directly above or may be an upper part (when another layer is interposed). In other places as well, it can be interpreted broadly.

  Application Example 2 In the thermal detector according to the application example described above, a first optical resonator for a first wavelength is formed between the support member and the first plane, and the support member and the second plane It is desirable that a second optical resonator for a second wavelength different from the first wavelength is formed.

  According to this configuration, since the plurality of optical resonators are provided, the optical resonance can be set to different wavelengths, and the light causing the optical resonance can be efficiently absorbed by the support member.

  Application Example 3 In the thermal detector according to the application example described above, an area in which the first plane and the support member overlap in a plan view viewed from the thickness direction of the substrate, the second plane, and the support It is desirable that the area where the member overlaps is the same.

  According to this configuration, since the area where the first plane and the support member overlap in plan view and the area where the second plane and the support member overlap are the same, the optical resonance on each surface is the same. By doing so, it is possible to balance both measurement sensitivities.

  Application Example 4 In the thermal detector according to the application example described above, a first side wall that connects the first plane and the second plane of the recess, and a connection between the second plane and the opening of the recess. It is desirable that the second side wall be formed in a tapered shape with an opening that increases toward the support member.

According to this configuration, the first side wall and the second side wall are formed in a tapered shape in which the opening becomes larger toward the support member.
Since the side wall has a tapered shape, there is no portion where incident light is blocked, and light transmitted from the support member can be sufficiently received by the first plane and the second plane.

  Application Example 5 In the thermal detector according to the application example described above, it is preferable that a reflection film that reflects light is formed on the first side wall and the second side wall.

  According to this configuration, the reflective film is formed on the first side wall and the second side wall. For this reason, the light which permeate | transmits from a supporting member can be reflected by each side wall, can be absorbed by a supporting member, and efficiency can be achieved.

  Application Example 6 A thermal detector according to this application example is a substrate, a spacer member formed on the substrate, having a first recess and a second recess, and facing the first recess of the spacer member. A first support member supported by the spacer member; a second support member facing the second recess of the spacer member and supported by the spacer member; and a first support member formed on the first support member for detecting heat. A first heat detection element and a second heat detection element formed on the second support member for detecting heat, wherein the first recess is formed on the bottom surface in a direction intersecting the thickness direction of the spacer member. The second recess has a second plane formed in a direction crossing the thickness direction of the spacer member on a bottom surface having a depth different from that of the first recess. Plane and said second plane Wherein the reflective film that reflects light is formed on.

According to this configuration, the spacer member is provided with the first concave portion (cavity portion) and the second concave portion (cavity portion), and the respective bottom surfaces are formed at different depths. That is, light of different wavelengths reflected by the first plane and the second plane can be absorbed by each support member.
Thus, the thermal detector of this application example can capture a wide range of wavelengths of light and set a wide wavelength band for measurement.

  Application Example 7 In the thermal detector according to the application example described above, a first optical resonator for a first wavelength is formed between the support member and the first plane, and the support member and the second plane It is desirable that a second optical resonator for a second wavelength different from the first wavelength is formed.

  According to this configuration, since the plurality of optical resonators are provided, the optical resonance can be set to different wavelengths, and the light causing the optical resonance can be efficiently absorbed by the support member.

  Application Example 8 In the thermal detector according to the application example, it is preferable that the areas of the first plane and the second plane are the same.

  According to this configuration, since the areas of the first plane and the second plane are the same, it is possible to balance both measurement sensitivities by making the optical resonances on the respective surfaces the same.

  Application Example 9 In the thermal detector according to the application example described above, the sidewalls of the first recess and the second recess have a tapered shape in which an opening increases toward the first support member or the second support member. It is desirable that it is formed.

According to this configuration, the side walls of the first recess and the second recess are formed in a tapered shape in which the opening becomes larger toward the support member.
Since the side wall is tapered, there is no portion where incident light is blocked, and light transmitted from the support member can be sufficiently received by the first plane and the second plane formed on the bottom surface of the recess.

  Application Example 10 In the thermal detector according to the application example described above, it is preferable that a reflective film that reflects light is formed on the sidewalls of the first recess and the second recess.

  According to this configuration, the reflective film is formed on the side wall. For this reason, the light which permeate | transmits from a supporting member can be reflected by each side wall, can be absorbed by a supporting member, and efficiency can be achieved.

  Application Example 11 A thermal detection device according to this application example is characterized in that it is two-dimensionally arranged using a plurality of the thermal detection detectors described above.

According to this configuration, the thermal detectors are two-dimensionally arranged along the biaxial direction.
This thermal detection device can provide a distribution image in a wide temperature range because the wavelength band measured by the thermal detection detector of each cell is wide.

  Application Example 12 An electronic apparatus according to this application example includes the above-described thermal detector and a control unit that processes an output of the thermal detector.

  An electronic apparatus according to this application example includes the above-described thermal detector or thermal detector, and uses a one-cell or multiple-cell thermal detector as a sensor, thereby distributing light (temperature) distribution. It can be used for thermography that outputs images, surveillance cameras, security equipment that detects fire and heat generation, process monitoring equipment provided in factories, and the like.

  Application Example 13 A manufacturing method of a thermal detector according to this application example includes a step of forming a first insulating layer on a substrate, forming a first trench in the first insulating layer, and the first trench. Forming a first reflective film on the surface on which the first reflective film is formed, forming a first sacrificial layer by filling the first trench from above the first reflective film, and forming a second sacrificial layer on the first sacrificial layer. Forming an insulating layer, forming a second trench in the second insulating layer having a larger opening than the first trench and including the first trench in plan view; and forming a second trench on the surface where the second trench is formed. A step of forming a second reflection film, a step of removing the second reflection film at a part of the bottom of the second trench, a step of filling the second trench to form a second sacrifice layer, and the second sacrifice Forming a support member on the layer; and a heat detection element on the support member. A step of forming, for removing a portion of the support member, and removing the first sacrificial layer and the second sacrificial layer, comprising a.

  According to this method for manufacturing a thermal detector, it is possible to form the bottom surface in the recess and another plane between the bottom surface and the opening. Thus, in the thermal detector, two planes can be formed in one recess, and optical resonance of light transmitted through the support member can be used between each plane and the support member.

  Application Example 14 A method for manufacturing a thermal detector according to this application example includes forming a first insulating layer on a substrate and forming a plurality of first trenches in the first insulating layer; Forming a first reflective film on a surface on which one trench is formed, filling the first trench from above the first reflective film to form a first sacrificial layer, and on the first sacrificial layer Forming a second insulating layer, forming a plurality of second trenches in the second insulating layer having a larger opening than the first trench and overlapping the first trench in plan view; and forming the second trench Forming a second reflective film on the finished surface, removing the second reflective film at the bottom of the selected second trench, forming a second sacrificial layer by filling the second trench, Forming a support member on the second sacrificial layer, and the support member Forming a heat detecting element on the substrate, removing a part of the support member, removing the second sacrificial layer, and removing the second reflective film in the second trench below the second reflective film. And 1 sacrificial layer removal step.

According to this method for manufacturing a thermal detector, recesses having different depths can be easily formed on one substrate.
In this manner, two concave portions having different depths can be formed on one substrate of the thermal detector, and the optical resonance of light transmitted through the support member is utilized between the plane of each concave portion and the support member. it can.

The schematic plan view which shows the structure of the infrared detector in 1st Embodiment. The schematic sectional drawing which shows the structure of the infrared detector in 1st Embodiment. Process drawing which shows the manufacturing process of the infrared detector in 1st Embodiment (the 1). Process drawing which shows the manufacturing process of the infrared detector in 1st Embodiment (the 2). Process drawing (the 3) which shows the manufacturing process of the infrared detector in 1st Embodiment. Process drawing (the 4) which shows the manufacturing process of the infrared detector in 1st Embodiment. The schematic plan view which shows the structure of the infrared detector in 2nd Embodiment. The schematic sectional drawing which shows the structure of the infrared detector in 2nd Embodiment. Process drawing which shows the manufacturing process of the infrared detector in 2nd Embodiment (the 1). Process drawing which shows the manufacturing process of the infrared detector in 2nd Embodiment (the 2). Process drawing which shows the manufacturing process of the infrared detector in 2nd Embodiment (the 3). Process drawing which shows the manufacturing process of the infrared detector in 2nd Embodiment (the 4). The circuit diagram which shows an example of the circuit structure of a thermal type photon detection apparatus. The block diagram which shows the structure of the infrared camera as an electronic device. The block diagram which shows the structure of the process monitoring apparatus as an electronic device.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. In the drawings used for the following description, the ratio of dimensions of each member is appropriately changed so that each member has a recognizable size.
(First embodiment)

In the following embodiment, a pyroelectric infrared detector will be described as an example of a thermal photodetector.
FIG. 1 is a schematic plan view showing the configuration of a pyroelectric infrared detector. FIG. 2 is a schematic cross-sectional view showing the configuration of a pyroelectric infrared detector. FIG. 1 is a plan view in which members above the wiring layer connected to the second electrode described later are omitted.

As shown in FIG. 2, the pyroelectric infrared detector 100 includes a silicon substrate 10, a spacer member 20, a support member (membrane) 40, and an infrared detection element 60.
A first insulating layer 21 and a second insulating layer 22 are sequentially stacked on the silicon substrate 10 to form a spacer member 20. The first insulating layer 21 and the second insulating layer 22 are made of an insulating material such as SiO ₂ .

A stepped recess 30 is formed in the spacer member 20. The recess 30 has a shape in which a recess 35 a formed in the first insulating layer 21 and a recess 35 b having a larger opening than the recess 35 a of the first insulating layer 21 formed in the second insulating layer 22 are overlapped. The recess 35a is disposed so as to cover half of the area of the support member 40 in plan view (see FIG. 1).
A first plane 31 that intersects the thickness direction of the spacer member 20 is formed on the bottom surface of the recess 30. Further, a second flat surface 32 that intersects the thickness direction of the spacer member 20 is formed on the bottom surface of the recess 35 b formed in the second insulating layer 22.
Note that the first plane 31 and the second plane 32 are preferably arranged in parallel to the surface of the support member 40.
The recess 35a is a recess having a distance D1 to the support member 40, and the recess 35b is a recess having a distance D2 to the support member 40.
As described above, the recess 30 has a shape having two planes in which the distance to the support member 40 is D1 and D2.

In addition, the first side wall 33 that connects the first plane 31 and the second plane 32 and the second side wall 34 that connects the second plane and the opening of the recess 30 have larger openings toward the opening of the recess 30. It is formed in a taper shape.
A reflective film 36 such as a Ti film that reflects infrared rays is formed on the first plane 31, the second plane 32, the first side wall 33, and the second side wall 34 of the recess 30. The reflective film 36 may be a laminated film in which a Ti film is formed on an AlO _x film or a SiN film.

A support member 40 that covers the recess 30 is provided on the spacer member 20. The support member 40 is formed of a SiN film or an AlO _x film.
The infrared detection element 60 is formed on one surface of the support member 40, and the other surface is disposed facing the recess 30.

The infrared detecting element 60 includes a capacitor 50 and an infrared absorbing member 70.
The capacitor 50 includes a first electrode 51, a second electrode 52, and a pyroelectric body 53. The pyroelectric body 53 is disposed between the first and second electrodes 51 and 52 and constitutes a capacitor 50 whose polarization amount changes based on temperature. The capacitor 50 is supported by mounting the first electrode 51 on the support member 40.
As the electrode material of the first electrode 51 and the second electrode 52, for example, Pt, Ir or the like is used. As the pyroelectric material of the pyroelectric body 53, for example, PZT (lead zirconate titanate), PZTN (PZT added with Nb), or the like is used.

A protective film 54 is formed on the surface of the capacitor 50 to protect the pyroelectric body 53 from a reducing atmosphere in the manufacturing process. Further, an insulating film 55 is formed so as to cover the protective film 54.
A contact hole 56 that communicates with the first electrode 51 and a contact hole 57 that communicates with the second electrode 52 are formed in the protective film 54 and the insulating film 55.

A first plug 61 is embedded in the contact hole 56. A first electrode wiring layer 58 connected to the first plug 61 is formed on the insulating film 55 and the support member 40.
Similarly, a second plug 62 is embedded in the contact hole 57. A second electrode wiring layer 59 connected to the second plug 62 is formed on the insulating film 55 and the support member 40.
As described above, the infrared detection element 60 includes the planar capacitor 50.

A SiO ₂ or SiN passivation film 63 is provided so as to cover the first and second electrode wiring layers 58 and 59. An infrared absorbing member 70 is provided on the passivation film 63 above the capacitor 50. This infrared absorbing member 70 is made of SiO ₂ or SiN.

A protective film 71 is provided to cover the outer surface of the infrared detector 100 including the infrared absorbing member 70.
The protective film 71 is formed of, for example, Al ₂ O _{3 and is} formed with a thickness of 10 to 50 nm, for example, 20 nm so as not to inhibit infrared transmission.

  As shown in FIG. 1, the support member 40 has two arms 45 for mounting and supporting the infrared detection element 60, and the free ends of the two arms 45 are connected to the post 28. The two arms 45 are formed in a narrow and long shape in order to thermally separate the infrared detection element 60.

  The infrared detector 100 is non-contact except that it is connected to the two posts 28. A recess 30 is formed below the infrared detector 100, and the recess 30 is formed around the infrared detector 100 in plan view. An opening 65 communicating with is disposed. Thereby, in the infrared detector 100, the infrared detection element 60 and the silicon substrate 10 are thermally separated.

(Infrared detector operation)
Next, the operation of the infrared detector 100 will be described.
A part of the light (infrared rays) incident on the infrared detecting element 60 of the infrared detector 100 is absorbed by the infrared absorbing member 70 and heat is generated in the infrared absorbing member 70. Further, the light reaching the surface of the support member 40 is absorbed by the support member 40 and heat is generated.
Further, the light transmitted through the support member 40 is reflected by the first plane 31 and the second plane 32 of the recess 30 and is absorbed by the support member 40 to generate heat.
The generated heat is transmitted to the capacitor 50, the amount of spontaneous polarization of the capacitor 50 is changed by the heat, and infrared rays are detected by detecting the charge due to the spontaneous polarization.
The light incident on the first side wall 33 and the second side wall 34 of the recess 30 is also reflected, and the light that reaches the support member 40 is absorbed by the support member 40.

Here, in the reflection of light in the concave portion 30, it is effective for the absorption of infrared rays by the support member 40 to cause optical resonance between the support member 40 and the bottom surface of the concave portion.
When the wavelength causing optical resonance is λ, the distance between two planes where optical resonance occurs is D, and the refractive index of the medium between the two planes is n, the relationship D = λ / 4n holds. Assuming that the refractive index n is in a vacuum and n = 1, it can be expressed as D = λ / 4.
From the above formula, if the wavelength of the infrared ray causing optical resonance is λ1 = 10 μm and λ2 = 5 μm, the distance between the two planes is D1 = 2.5 μm and D2 = 1.25 μm.
In FIG. 2, when D1 = 2.5 μm, an optical resonator for the infrared wavelength λ1 = 10 μm is formed between the support member 40 and the first plane 31.
Similarly, in FIG. 2, if D2 = 1.25 μm, an optical resonator for the infrared wavelength λ2 = 5 μm is formed between the support member 40 and the second plane 32.
As described above, two optical resonators can be formed between the support member 40 and the recess 30.
Note that λ1 = 10 μm as an infrared wavelength corresponds to a temperature of approximately 20 ° C., and λ2 = 5 μm corresponds to a temperature of approximately 300 ° C.

As described above, since the infrared detector 100 includes the optical resonator between the first plane and the second plane of the support member 40 and the recess, the optical resonance can be set to different wavelengths, and the light that causes the optical resonance can be set. It can be efficiently absorbed by the support member.
In addition, since the two optical resonators constitute resonance peaks at two different wavelengths, the peaks are combined and the wavelength band that can be detected by the infrared detector 100 is expanded. That is, the wavelength band (wavelength width) of light that can be detected by the infrared detector 100 can be expanded. Thus, the infrared detector 100 can capture a wide range of wavelengths of light and set a wide wavelength band for measurement.

Moreover, it is desirable that the area where the first plane 31 and the support member 40 overlap is the same as the area where the second plane 32 and the support member 40 overlap in a plan view as viewed from the thickness direction of the silicon substrate 10. .
According to this configuration, it is possible to balance both measurement sensitivities by making the optical resonances on the respective surfaces the same.

(Infrared detector manufacturing method in the first embodiment)
Next, a method for manufacturing the infrared detector will be described.
3 to 6 are process diagrams showing the manufacturing process of the infrared detector.
First, the silicon substrate 10 is prepared (FIG. 3A).
Next, a first insulating layer 21 such as SiO ₂ is formed on the silicon substrate 10, and a resist 80 is applied thereon to form an opening 81 in a portion where a first trench is to be formed (FIG. 3B). ). The first insulating layer 21 is formed by a technique such as sputtering or CVD.
Subsequently, etching is performed through the opening 81 of the resist 80 to form a first trench 82 in the first insulating layer 21 (FIG. 3C). Etching is performed by wet etching the first insulating layer 21 using a hydrofluoric acid-based solution.
Then, the resist 80 is removed, and a reflective film 36 that reflects infrared rays is formed on the surface of the first insulating layer 21 (FIG. 3D). As the reflective film 36, a Ti film, or a laminated film in which a Ti film is formed on an AlO _x film or SiN film is formed. This reflective film 36 also functions as a barrier film when etching the SiO ₂ film in a later process.

Next, a first sacrificial layer 23 such as SiO ₂ is formed on the reflective film 36 (FIG. 4A). This film formation is performed until the first trench 82 is buried.
Then, the first sacrificial layer 23 is subjected to chemical mechanical polishing (CMP) (FIG. 4B). Polishing is performed so that the first sacrificial layer 23 and the reflective film 36 embedded in the first trench 82 become flat.
Subsequently, a second insulating layer 22 such as SiO _{2 is} formed on the CMP processed surface, and a resist 80 is applied thereon to form an opening 83 in a portion where a second trench is to be formed (FIG. 4C). )). The position where the second trench is formed here is a position including the first trench 82 in plan view, and is formed at a position shifted in one direction.
The material of the second insulating layer 22 is preferably the same material as that of the first insulating layer 21.
Then, etching is performed through the opening 83 of the resist 80 to form a second trench 84 having a larger opening than the first trench 82 in the second insulating layer 22 (FIG. 4D). Etching is performed in the same manner as the etching of the first insulating layer 21.

Next, the resist 80 is removed, and a reflective film 36 that reflects infrared rays is formed on the surface of the second insulating layer 22 (FIG. 5A). As the reflective film 36, a Ti film, or a laminated film in which a Ti film is formed on an AlO _x film or SiN film is formed. This reflective film 36 also functions as a barrier film when etching the SiO ₂ film in a later process.
Then, the reflective film 36 formed on the first sacrificial layer 23 is removed by patterning (FIG. 5B). In this way, an opening 85 is formed on the first sacrificial layer 23.
Subsequently, a second sacrificial layer 24 such as SiO ₂ is formed on the reflective film 36 (FIG. 5C). This film formation is performed until the second trench 84 is filled.
Then, the second sacrificial layer 24 is subjected to CMP processing (FIG. 5D). Polishing is performed so that the second sacrificial layer 24 and the reflective film 36 embedded in the second trench 84 become flat.

Next, the supporting member 40 is formed on the CMP processed surface, and the infrared detecting element 60 and the protective film 71 are formed on the supporting member 40 (FIG. 6A).
The infrared detection element 60 is formed by forming the capacitor 50 and wiring (not shown) on the support member 40 and then forming the infrared absorption member 70 on the capacitor 50.
The protective film 71 is provided so as to cover the outer surface of the infrared detector including the infrared absorbing member 70 with an Al ₂ O ₃ film or the like.
Then, an opening 86 is formed in the protective film 71 and the support member 40 in order to etch the first and second sacrificial layers 23 and 24. Although not shown, the support member 40 is simultaneously etched to form an arm (FIG. 6B).
Subsequently, the second sacrificial layer 24 is etched through the opening 86 and the like, and further the etching is continued to etch the first sacrificial layer 23 to form the recess 30. In etching these sacrificial layers, techniques such as wet etching, dry etching, and vapor phase etching can be used.
In this way, the first plane 31 and the second plane 32 can be easily formed in the recess 30 of the infrared detector 100.
(Second Embodiment)

Next, another embodiment of the infrared detector will be described.
The infrared detector according to the present embodiment is different from the first embodiment in that a single substrate (cell) has a plurality of recesses having different depths.
FIG. 7 is a schematic plan view showing the configuration of a pyroelectric infrared detector. FIG. 8 is a schematic cross-sectional view showing the configuration of a pyroelectric infrared detector.
In the description of this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

As shown in FIG. 8, the pyroelectric infrared detector 200 includes a first infrared detector 200a and a second infrared detector 200b.
The first infrared detector 200a and the second infrared detector 200b share the silicon substrate 10 and the spacer member 20, and have support members 40a and 40b and infrared detection elements 60a and 60b, respectively. Yes.

The spacer member 20 is formed with two recesses 30a and 30b.
The concave portion 30a of the first infrared detector 200a passes through the second insulating layer 22 and reaches the first insulating layer 21, and the distance between the bottom of the concave portion 30a and the support member 40a is set to D1.
The recess 30b of the second infrared detector 200b stops when it passes through the second insulating layer 22, and the distance between the bottom of the recess 30b and the support member 40b is set to D2.
A first plane 31a that intersects or is orthogonal to the thickness direction of the spacer member 20 is formed on the bottom surface of the recess 30a. In addition, a second flat surface 32a that intersects or is orthogonal to the thickness direction of the spacer member 20 is formed on the bottom surface of the recess 30b.
As described above, the infrared detector 200 is formed with two concave portions 30a and 30b, and each concave portion has a shape having two planes whose distances to the support member are D1 and D2.
The distances D1 and D2 between the first plane 31a and the second plane 32a and the support member are set to the distances at which optical resonance occurs in light of a specific wavelength. For example, the wavelengths of infrared rays causing optical resonance are λ1 = 10 μm, = 5 μm, D1 = 2.5 μm and D2 = 1.25 μm.

Further, the side wall 37 connecting the first flat surface 31a of the recess 30a and the opening is formed in a tapered shape in which the opening becomes larger toward the opening of the recess 30a.
Similarly, the side wall 38 that connects the second flat surface 32a of the recess 30b and the opening is formed in a tapered shape in which the opening increases toward the opening of the recess 30b.

A support member 40a is provided above the recess 30a, and a support member 40b is provided above the recess 30b.
And the infrared detection element 60a is formed in one surface of the supporting member 40a, and the other surface is arrange | positioned facing the recessed part 30a. Similarly, an infrared detection element 60b is formed on one surface of the support member 40b, and the other surface is disposed facing the recess 30b.

Each of the infrared detecting elements 60a and 60b includes a capacitor 50 and an infrared absorbing member 70. Since these configurations are the same as those in the first embodiment, the description thereof is omitted here.
A protective film 71 is provided to cover the outer surface of the infrared detector including the infrared absorbing member 70.

As shown in FIG. 7, the support member 40 a has two arms 45 for mounting and supporting the infrared detection element 60 a, and the free ends of the two arms 45 are connected to the post 28. The two arms 45 are formed in a narrow and long shape in order to thermally separate the infrared detection element 60a.
Similarly, the support member 40 b has two arms 45 for mounting and supporting the infrared detection element 60 b, and the free ends of the two arms 45 are connected to the post 28. The two arms 45 are formed in a narrow and long shape in order to thermally separate the infrared detection element 60b.

  In the infrared detector 200, the first infrared detector 200 a and the second infrared detector 200 b are non-contact except that they are connected to the two posts 28. And the recessed part 30a, 30b is formed under the 1st infrared detector 200a and the 2nd infrared detector 200b, and the opening part 65 connected to the recessed part 30a, 30b is formed in the circumference | surroundings of the infrared detector 200 by planar view. Be placed. Thereby, in the infrared detector 200, the infrared detection elements 60a and 60b and the silicon substrate 10 are thermally separated.

(Infrared detector operation)
Next, the operation of the infrared detector will be described.
Part of the light (infrared rays) incident on the infrared detecting element 60a of the first infrared detector 200a is absorbed by the infrared absorbing member 70, and heat is generated in the infrared absorbing member 70. Further, the light reaching the surface of the support member 40a is absorbed by the support member 40a and heat is generated.
Further, the light transmitted through the support member 40a is reflected by the first plane 31a of the recess 30a constituting the optical resonator, and is absorbed by the support member 40a to generate heat.
The generated heat is transmitted to the capacitor 50, the amount of spontaneous polarization of the capacitor 50 is changed by the heat, and infrared rays are detected by detecting the charge due to the spontaneous polarization.
Note that light incident on the side wall 37 of the recess 30a is also reflected and absorbed by the support member 40a.

Further, a part of the light (infrared rays) incident on the infrared detecting element 60 b of the second infrared detector 200 b is absorbed by the infrared absorbing member 70, and heat is generated in the infrared absorbing member 70. The light that reaches the surface of the support member 40b is absorbed by the support member 40b and heat is generated.
Further, the light transmitted through the support member 40b is reflected by the second plane 32a of the recess 30b constituting the optical resonator, and is absorbed by the support member 40b to generate heat.
The generated heat is transmitted to the capacitor 50, the amount of spontaneous polarization of the capacitor 50 is changed by the heat, and infrared rays are detected by detecting the charge due to the spontaneous polarization.
Note that light incident on the side wall 38 of the recess 30b is also reflected and absorbed by the support member 40b.
As described above, two optical resonators corresponding to different wavelengths of light are formed between the support member and the recess.
As an infrared wavelength, λ1 = 10 μm corresponds to a temperature of about 20 ° C., and λ2 = 5 μm corresponds to a temperature of about 300 ° C.

As described above, the infrared detector 200 includes the first infrared detector 200a and the second infrared detector 200b. And, since it has two concave portions 30a and 30b with different depths, and has an optical resonator between the support member 40a and the first plane 31a, and between the support member 40b and the second plane 32a, the optical resonance is different in wavelength. The light that has caused this optical resonance can be efficiently absorbed by the support member.
In addition, since two optical resonators constitute resonance peaks at two different wavelengths, the wavelength band in which the thermal photodetector has detection sensitivity is expanded by combining the peaks. . That is, the wavelength band (wavelength width) of light that can be detected by the infrared detector 200 can be expanded. Thus, the infrared detector 200 can capture the wavelength of light in a wide range and set a wide wavelength band for measurement.

  Moreover, it is desirable that the areas of the first plane 31a and the second plane 32a constituting the optical resonator are the same. If the areas of the first plane 31a and the second plane 32a are the same, it is possible to balance both measurement sensitivities by making the optical resonances of the respective planes the same.

(Infrared detector manufacturing method in the second embodiment)
The infrared detector in the present embodiment can be manufactured in the same process as the infrared detector in the first embodiment, and the manufacturing method will be briefly described below.
9-12 is process drawing which shows the manufacturing process of an infrared detector.
First, the silicon substrate 10 is prepared (FIG. 9A).
Next, a first insulating layer 21 such as SiO ₂ is formed on the silicon substrate 10, and a resist 90 is applied thereon to form openings 91 in portions where a plurality of first trenches are to be formed (FIG. 9 ( b)).
Subsequently, etching is performed through the opening 91 of the resist 90 to form first trenches 92a and 92b in the first insulating layer 21 (FIG. 9C).
Then, the resist 90 is removed, and a reflective film 36 that reflects infrared rays is formed on the surface of the first insulating layer 21 (FIG. 9D).

Next, a first sacrificial layer 23 such as SiO ₂ is formed on the reflective film 36 (FIG. 10A).
Then, the first sacrificial layer 23 is subjected to chemical mechanical polishing (CMP) (FIG. 10B).
Subsequently, a second insulating layer 22 such as SiO _{2 is} formed on the surface subjected to CMP, and a resist 90 is applied thereon to form openings 93 in portions where a plurality of second trenches are to be formed (FIG. 10 ( c)).
Then, etching is performed through the opening 93 of the resist 90 to form second trenches 94a and 94b in the second insulating layer 22 (FIG. 10D). The second trenches 94a and 94b have openings larger than the first trenches 92a and 92b, and are formed at positions overlapping the first trenches 92a and 92b in plan view.

Next, the resist 90 is removed, and a reflective film 36 that reflects infrared rays is formed on the surface of the second insulating layer 22 (FIG. 11A).
Then, the reflective film 36 formed on the bottom surface of the second trench 94a is patterned and removed (FIG. 11B). In this way, an opening 95 is formed on the first sacrificial layer 23.
Subsequently, a second sacrificial layer 24 such as SiO ₂ is formed on the reflective film 36 (FIG. 11C).
Then, the second sacrificial layer 24 is subjected to CMP processing (FIG. 11D).

Next, support members 40a and 40b are formed on the CMP processed surface, and infrared detection elements 60a and 60b and a protective film 71 are formed on the support members 40a and 40b (FIG. 12A).
The infrared detection elements 60a and 60b are formed by forming the capacitor 50 and wiring (not shown) on the support members 40a and 40b, and then forming the infrared absorbing member 70 on the capacitor 50.
The protective film 71 is provided so as to cover the outer surface of the infrared detector including the infrared absorbing member 70 with an Al ₂ O ₃ film or the like.
Then, an opening 96 for etching the first and second sacrificial layers 23 and 24 is formed. Although not shown, the support members 40a and 40b are simultaneously etched to form arms (FIG. 12B).
Subsequently, the recess 30b is formed by etching the second sacrificial layer 24 of the second trench 94b through the opening 96 or the like. At the same time, the second sacrificial layer 24 of the second trench 94a is etched. Etching is then continued to etch the first sacrificial layer 23 of the first trench 92a to form a recess 30a (FIG. 12C).
In this way, the first infrared detector 200a and the second infrared detector 200b are formed in the infrared detector 200.
As described above, by providing the infrared detector 200 with the concave portions 30a and 30b having different depths, the first plane 31a and the second plane 32a can be easily formed on the respective bottom surfaces.

In the infrared detectors of the first embodiment and the second embodiment, the pyroelectric capacitor has been described as an example of the heat detection element. However, the thermal detector is not limited to the pyroelectric capacitor, and the resistance increases due to a temperature rise. Even a bolometer using a changing substance can be implemented.
Further, in the infrared detectors of the first embodiment and the second embodiment, the plane for forming the optical resonator is formed at two kinds of depths, but the plane may be formed at three or more kinds of depths.
(Third embodiment)

  FIG. 13 is a circuit diagram illustrating an example of a circuit configuration of a thermal detection device (thermal detection array sensor). In the thermal detection device 300, a plurality of thermal detectors 300a to 300d are two-dimensionally arranged. Scan lines W1a and W1b and data lines D1a and D1b are provided to select one photodetection cell from among the plurality of thermal detectors 300a to 300d.

  The thermal photodetector 300a as the first photodetector cell includes a piezoelectric capacitor ZC as a thermal photodetector element and an element selection transistor M1a. The potential relationship between the two electrodes of the piezoelectric capacitor ZC can be reversed by switching the potential applied to RDr1. The other light detection cells have the same configuration.

  The potential of the data line D1a can be initialized by turning on the reset transistor M2. When reading the detection signal, the read transistor M3 is turned on. A current generated by the pyroelectric effect is converted into a voltage by the I / V conversion circuit 310, amplified by the amplifier 320, and converted into digital data by the A / D converter 330.

In the present embodiment, a thermal photodetection device (thermal photodetection array sensor) in which a plurality of thermal detectors are two-dimensionally arranged is realized.
(Fourth embodiment)

Next, electronic devices including a thermal detector or a thermal photodetector will be described.
FIG. 14 illustrates a configuration of an infrared camera as an example of an electronic device.
The infrared camera 400 includes an optical system 410, a sensor device (thermal detection device) 420, an image processing unit 430, a processing unit 440, a storage unit 450, an operation unit 460, and a display unit 470.

  The optical system 410 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 420. Also, focus adjustment is performed as necessary.

  The sensor device 420 is configured by two-dimensionally arranging the thermal detectors of the present embodiment described above, and is provided with a plurality of row lines (word lines, scanning lines) and a plurality of column lines (data lines). In addition to the detector, the sensor device 420 can include a row selection circuit (row driver), a read circuit that reads data from the detector via a column line, an A / D converter, and the like. 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 430 performs various types of image processing such as image correction processing based on digital image data (pixel data) from the sensor device 420.

  The processing unit 440 controls the entire infrared camera 400 and controls each block in the infrared camera 400. The processing unit 440 is realized by a CPU, for example. The storage unit 450 stores various types of information, and functions as a work area for the processing unit 440 and the image processing unit 430, for example. The operation unit 460 serves as an interface for the user to operate the infrared camera 400, and is realized by, for example, various buttons, a GUI (Graphical User Interface) screen, or the like. The display unit 470 displays, for example, an image acquired by the sensor device 420 or a GUI screen, and is realized by various displays such as a liquid crystal display and an organic EL display.

  Thus, in addition to using a thermal detector for one cell as a sensor such as an infrared sensor, a sensor device can be obtained by two-dimensionally arranging a thermal detector for one cell in a biaxial direction, for example, an orthogonal biaxial direction. 420 can be configured and a heat (light) distribution image can be provided. Using the sensor device 420, an electronic device such as a thermography or a surveillance camera can be configured.

Of course, analysis equipment (measuring equipment) that analyzes (measures) physical information of an object by using a thermal detector for one cell or multiple cells as a sensor, security equipment that detects fire and heat, processes such as factories Various electronic devices such as monitoring devices can also be configured.
(Fifth embodiment)

  FIG. 15 shows a configuration of a process monitoring apparatus as an example of an electronic apparatus including the thermal photodetector or the thermal photodetector of the present embodiment. The process monitoring device is a device that monitors the temperature (heat generation) of a device such as a factory and warns a person when the device is abnormal when the device is abnormal.

As shown in FIG. 15, the process monitoring apparatus 500 includes an infrared camera 510, a temperature analysis unit 520, a person detection unit 530, a control unit 540, and an information notification device 550.
The infrared camera 510 includes an optical system such as a lens (not shown) and a sensor device.

The infrared camera 510 captures the target area of the process and transmits image information of the captured area to the temperature analysis unit 520. In the temperature analysis unit 520, although not shown, an image reading processing unit that reads a heat distribution image from the infrared camera 510, and a temperature analysis processing unit that creates a temperature analysis table based on data from the image reading processing unit and an image analysis setting table. The temperature data is transmitted to the control unit 540 based on the temperature analysis table.
In addition, the human detection unit 530 detects from the information from the infrared camera 510 whether or not there is a human 570 in the target area. This detection is performed from the body temperature and movement of the human 570. Information in the human detection unit 530 is sent to the control unit 540.
Then, the control unit 540 determines whether there is an abnormality in the device 560 in the process based on the data sent from the temperature analysis unit 520. When there is an abnormality such as a high temperature of the device 560, data is transmitted to the information notification device 550, and the information notification device 550 notifies the abnormality.
In addition, when the device 560 has an abnormality and the human 570 detects that the human 570 is approaching, the control unit 540 transmits data to the information notification device 550 and notifies the human 570 by an alarm such as an alarm.

  The present invention is not limited to the embodiment described above, and the specific structure and procedure for carrying out the present invention can be appropriately changed to other structures and the like as long as the object of the present invention can be achieved. it can. Many modifications can be made by those skilled in the art within the technical idea of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Silicon substrate, 20 ... Spacer member, 21 ... 1st insulating layer, 22 ... 2nd insulating layer, 23 ... 1st sacrificial layer, 24 ... 2nd sacrificial layer, 28 ... Post, 30 ... Recessed part, 30a ... 1st Recess, 30b ... second recess, 31 ... first plane, 31a ... first plane, 32 ... second plane, 32a ... second plane, 33 ... first side wall, 34 ... second side wall, 35a, 35b ... recess, 36 ... reflective film 37 ... side wall 38 ... side wall 40 ... support member 40a ... first support member 40b ... second support member 45 ... arm 50 ... capacitor 51 ... first electrode 52 ... second Electrode 53 ... Pyroelectric body 54 ... Protective film 55 ... Insulating film 56,57 ... Contact hole 58 ... First electrode wiring layer 59 ... Second electrode wiring layer 60 ... Infrared detecting element 60a, 60b ... Infrared detector, 61 ... first plug, 62 ... second plug 63 ... Passivation film, 65 ... Opening, 70 ... Infrared absorbing member, 71 ... Protective film, 82 ... First trench, 84 ... Second trench, 92a, 92b ... First trench, 94a, 94b ... Second trench, 100 ... an infrared detector as a thermal detector, 200 ... an infrared detector as a thermal detector, 200a ... a first infrared detector, 200b ... a second infrared detector, 300 ... a thermal detector (heat Type optical detection array sensor), 400... Infrared camera as electronic device, 420... Sensor device, 500.

Claims (14)

A substrate,
A spacer member formed on the substrate and having a recess;
A support member facing the recess of the spacer member and supported by the spacer member;
A heat detecting element formed on the support member for detecting heat,
The recess has a first plane formed on the bottom surface in a direction intersecting the thickness direction of the spacer member, and a direction intersecting the thickness direction of the spacer member between the bottom surface and the support member. A second plane formed on
A thermal detector, wherein a reflection film that reflects light is formed on the first plane and the second plane. The thermal detector according to claim 1, wherein
A first optical resonator for a first wavelength is formed between the support member and the first plane;
A thermal optical detector, wherein a second optical resonator for a second wavelength different from the first wavelength is formed between the support member and the second plane. The thermal detector according to claim 1 or 2,
The area in which the first plane and the support member overlap in the plan view viewed from the thickness direction of the substrate is the same as the area in which the second plane and the support member overlap. Type photodetector. The thermal detector according to any one of claims 1 to 3,
The first side wall connecting the first plane and the second plane of the recess and the second side wall connecting the second plane and the opening of the recess are tapered so that the opening increases toward the support member. A thermal detector that is formed. The thermal detector according to claim 4, wherein
A thermal detector, wherein a reflection film for reflecting light is formed on the first side wall and the second side wall. A substrate,
A spacer member formed on the substrate and having a first recess and a second recess;
A first support member facing the first recess of the spacer member and supported by the spacer member;
A second support member that faces the second recess of the spacer member and is supported by the spacer member;
A first heat detection element formed on the first support member for detecting heat;
A second heat detection element formed on the second support member for detecting heat,
The first recess includes a first plane formed on the bottom surface in a direction intersecting the thickness direction of the spacer member,
The second recess includes a second flat surface formed in a direction intersecting the thickness direction of the spacer member on a bottom surface having a depth different from that of the first recess.
A thermal detector, wherein a reflection film that reflects light is formed on the first plane and the second plane. The thermal detector according to claim 6, wherein
A first optical resonator for a first wavelength is formed between the support member and the first plane;
A thermal optical detector, wherein a second optical resonator for a second wavelength different from the first wavelength is formed between the support member and the second plane. The thermal detector according to claim 6 or 7,
The thermal detector having the same area as the first plane and the second plane. The thermal detector according to any one of claims 6 to 8,
The thermal detector according to claim 1, wherein sidewalls of the first recess and the second recess are formed in a tapered shape with an opening increasing toward the first support member or the second support member. The thermal detector according to claim 9, wherein
A thermal detector, wherein a reflective film that reflects light is formed on the side walls of the first recess and the second recess.   A thermal detection device, wherein a plurality of the thermal detectors according to claim 1 are used and two-dimensionally arranged.   An electronic apparatus comprising: the thermal detector according to any one of claims 1 to 10; and a control unit that processes an output of the thermal detector. Forming a first insulating layer on the substrate and forming a first trench in the first insulating layer;
Forming a first reflective film on the surface on which the first trench is formed;
Filling the first trench from above the first reflective film to form a first sacrificial layer;
Forming a second insulating layer on the first sacrificial layer, and forming a second trench having a larger opening than the first trench in the second insulating layer and including the first trench in plan view;
Forming a second reflective film on the surface on which the second trench is formed;
Removing a part of the second reflective film at the bottom of the second trench;
Forming a second sacrificial layer by filling the second trench;
Forming a support member on the second sacrificial layer;
Forming a heat detection element on the support member;
Removing a part of the support member;
Removing the first sacrificial layer and the second sacrificial layer;
The manufacturing method of the thermal type photodetector characterized by including. Forming a first insulating layer on the substrate and forming a plurality of first trenches in the first insulating layer;
Forming a first reflective film on the surface on which the first trench is formed;
Filling the first trench from above the first reflective film to form a first sacrificial layer;
Forming a second insulating layer on the first sacrificial layer, and forming a plurality of second trenches in the second insulating layer having an opening larger than the first trench and overlapping the first trench in plan view; When,
Forming a second reflective film on the surface on which the second trench is formed;
Removing the second reflective film at the bottom of the selected second trench;
Forming a second sacrificial layer by filling the second trench;
Forming a support member on the second sacrificial layer;
Forming a heat detection element on the support member;
Removing a part of the support member;
Removing the second sacrificial layer;
Removing the first sacrificial layer below the deleted second reflective film in the second trench;
The manufacturing method of the thermal type photodetector characterized by including.

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