Optical sensor

Abstract

To provide an optical sensor which improves sensitivity and can improve a yield.SOLUTION: An optical sensor includes a support layer, a plurality of belt-like p-type material layers, and a plurality of belt-like n-type material layers, a thermoelectric conversion material part, a heat sink, a light absorption film, and an insulation film. The plurality of p-type material layers each includes a first region overlapped with the heat sink when being viewed in a direction perpendicular to a first main surface, and a second region overlapped with the light absorption film. The plurality of n-type material layers each includes a third region overlapped with the heat sink when being viewed in a direction perpendicular to the first main surface, and a fourth region overlapped with the light absorption film. The plurality of p-type material layers and the plurality of n-type material layers are each alternately arranged in series so that the first region and the third region are electrically connected to each other, and the second region and the fourth region are electrically connected to each other. The light absorption film is composed of carbon and a resin. The light absorption film is divided into a plurality of division parts by a recessed groove recessed in a thickness direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to optical sensors. [Background technology]

[0002] There is known technology relating to a thermopile-type infrared sensor that uses a thermoelectric conversion material that converts a temperature difference (thermal energy) into electrical energy (see, for example, Patent Document 1). The infrared sensor comprises a light receiving section (light absorbing film) that converts light energy into thermal energy, and a thermoelectric conversion material section (thermopile) that converts the temperature difference (thermal energy) into electrical energy. The thermoelectric conversion section uses a thermocouple formed by connecting a p-type thermoelectric conversion material and an n-type thermoelectric conversion material. The output is increased by alternately connecting multiple p-type thermoelectric conversion materials and multiple n-type thermoelectric conversion materials in series. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-340848 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the optical sensor, a temperature difference is formed in response to the light received by the light absorbing film, and this temperature difference (thermal energy) is converted into electrical energy. In the optical sensor, it is required to improve the sensitivity and the yield.

[0005] Therefore, an object of the present invention is to provide an optical sensor that can improve the sensitivity and also the yield. [Means for solving the problem]

[0006] The optical sensor according to the present disclosure includes a support layer having a first main surface and a second main surface located opposite to the first main surface in the thickness direction, a plurality of strip-shaped p-type material layers made of SiGe having a p-type conductivity and converting thermal energy into electrical energy, and a plurality of strip-shaped n-type material layers made of SiGe having an n-type conductivity and converting thermal energy into electrical energy, and includes a thermoelectric conversion material portion disposed on the first main surface, a heat sink disposed on the second main surface and having a recess on the inside as viewed in a direction perpendicular to the first main surface, a light absorbing film disposed overlapping the recess as viewed in a direction perpendicular to the first main surface, and an insulating film disposed between the thermoelectric conversion material portion and the light absorbing film. Each of the plurality of p-type material layers includes a first region overlapping the heat sink as viewed in a direction perpendicular to the first main surface and a second region overlapping the light absorbing film. Each of the plurality of n-type material layers includes a third region overlapping the heat sink as viewed in a direction perpendicular to the first main surface and a fourth region overlapping the light absorbing film. The multiple p-type material layers and multiple n-type material layers are alternately arranged in series such that the first region and the third region are electrically connected, and the second region and the fourth region are electrically connected. The light absorbing film is made of carbon and resin. The light absorbing film is divided into multiple divisions by grooves recessed in the thickness direction. Effect of the Invention

[0007] The optical sensor described above can improve the sensitivity and the yield. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic plan view of the appearance of an optical sensor in accordance with the first embodiment. [Diagram 2] FIG. 2 is a schematic plan view showing a state in which an infrared absorbing film serving as a light absorbing film and an insulating film, which will be described later, are removed from the optical sensor shown in FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view of the optical sensor according to the first embodiment taken along line III-III in FIG. [Figure 4] FIG. 4 is an enlarged view of a portion indicated by region IV in FIG. [Diagram 5] FIG. 5 is a schematic cross-sectional view of the optical sensor according to the first embodiment taken along line segment VV in FIG. [Figure 6] FIG. 6 shows the analysis results of a conventional optical sensor model, showing the displacement of the support layer at -65°C. [Figure 7] FIG. 7 shows the analysis results of a conventional optical sensor model, showing the displacement of the support layer at 350°C. [Figure 8] FIG. 8 is a schematic diagram showing the analysis result of the model of the optical sensor according to the first embodiment, illustrating the displacement amount of the infrared absorbing film at -65°C. [Figure 9] FIG. 9 is a schematic diagram showing the analysis result of the model of the optical sensor according to the first embodiment, illustrating the displacement amount of the infrared absorbing film at 350° C. [Figure 10] FIG. 10 is a graph showing the displacement amount and position of the support layer at −65° C. in a model of a conventional optical sensor. [Figure 11] FIG. 11 is a graph showing the displacement amount and position of the support layer at 350° C. in a model of a conventional optical sensor. [Figure 12] FIG. 12 is a graph showing the displacement amount and position of the support layer at −65° C. in the model of the optical sensor according to the first embodiment. [Figure 13] FIG. 13 is a graph showing the displacement amount and position of the support layer at 350° C. in the model of the optical sensor according to the first embodiment. [Figure 14] FIG. 14 is a schematic diagram showing stress generated in an infrared absorbing film in a CAE analysis of stress in a conventional optical sensor model. [Figure 15] FIG. 15 is a schematic diagram showing stress generated in an infrared absorbing film in a CAE analysis of stress in a model of the optical sensor according to the first embodiment. [Figure 16] FIG. 16 is a schematic plan view of an external appearance of an infrared absorbing film included in an optical sensor according to the second embodiment of this disclosure. [Figure 17] FIG. 17 is a schematic plan view of an external appearance of an infrared absorbing film included in the optical sensor according to the third embodiment of this disclosure. [Figure 18] FIG. 18 is a schematic plan view of an external appearance of an infrared absorbing film included in the optical sensor according to the fourth embodiment of this disclosure. [Figure 19] FIG. 19 is a schematic plan view of an external appearance of an infrared absorbing film included in an optical sensor according to the fifth embodiment of this disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described. (1) The optical sensor according to the present disclosure includes a support layer having a first main surface and a second main surface located opposite to the first main surface in the thickness direction, a plurality of strip-shaped p-type material layers made of SiGe having a p-type conductivity and converting thermal energy into electrical energy, and a plurality of strip-shaped n-type material layers made of SiGe having an n-type conductivity and converting thermal energy into electrical energy, and includes a thermoelectric conversion material portion disposed on the first main surface, a heat sink disposed on the second main surface and having a recess on the inside as viewed in a direction perpendicular to the first main surface, a light absorbing film disposed overlapping the recess as viewed in a direction perpendicular to the first main surface, and an insulating film disposed between the thermoelectric conversion material portion and the light absorbing film. Each of the plurality of p-type material layers includes a first region overlapping the heat sink as viewed in a direction perpendicular to the first main surface, and a second region overlapping the light absorbing film. Each of the plurality of n-type material layers includes a third region overlapping the heat sink as viewed in a direction perpendicular to the first main surface, and a fourth region overlapping the light absorbing film. The multiple p-type material layers and multiple n-type material layers are alternately arranged in series such that the first region and the third region are electrically connected, and the second region and the fourth region are electrically connected. The light absorbing film is made of carbon and resin. The light absorbing film is divided into multiple divisions by grooves recessed in the thickness direction.

[0010] In the thermoelectric conversion material section, for example, a thermocouple formed by connecting a p-type thermoelectric conversion material and an n-type thermoelectric conversion material section may be used. The output is increased by alternately connecting a plurality of strip-shaped p-type thermoelectric conversion material sections and a plurality of strip-shaped n-type thermoelectric conversion material sections in series. The sensitivity of the optical sensor is expressed by the following formula 1.

number

[0011] Here, the inventors considered increasing the temperature difference that is approximately equal to the inverse of the thermal conductance when reducing the thermal conductance. As a result, they found that, among the components included in the optical sensor, the light absorbing film that forms a temperature difference in the thermoelectric conversion material section has a high thermal conductivity, which reduces the temperature difference formed in the thermoelectric conversion material section. In other words, they considered that, in the region of the thermoelectric conversion material section that overlaps with the light absorbing film and becomes hot, if the light absorbing film has a high thermal conductivity, this region will have the same temperature, making it difficult to form a temperature difference.

[0012] According to the optical sensor of the present disclosure, since an insulating film is disposed between the thermoelectric conversion material section and the light absorbing film, it is possible to ensure insulation between the thermoelectric conversion material section and the light absorbing film. In addition, since the light absorbing film that forms a temperature difference between each of the plurality of strip-shaped p-type material layers and the plurality of strip-shaped n-type material layers included in the thermoelectric conversion material section is made of carbon and resin, it is possible to realize a high light absorption rate while reducing the thermal conductivity. In other words, it is possible to achieve both low thermal conductivity and high light absorption rate. Therefore, it is possible to improve the sensitivity. In addition, since the light absorbing film is divided into a plurality of division parts by the groove, it is possible to alleviate the stress generated in the light absorbing film when a high temperature difference occurs. Therefore, even if a high temperature difference occurs, it is possible to suppress damage to the light absorbing film. As a result, it is possible to improve the yield of the optical sensor. As described above, according to such an optical sensor, it is possible to improve the sensitivity and improve the yield.

[0013] (2) In the above (1), the outer shape of the light absorbing film may be rectangular when viewed in a direction perpendicular to the first main surface. The outer shapes of the multiple divisions may each be rectangular. In this way, the multiple divisions can be arranged along the overall outer shape of the light absorbing film, and damage to the light absorbing film when a large temperature difference occurs can be more reliably suppressed. Therefore, the yield can be more reliably improved.

[0014] (3) In the above (1) or (2), the multiple divisions may include a first division and a second division arranged closer to the outer periphery of the light absorbing film than the first division when viewed in a direction perpendicular to the first main surface. The area of ​​the first division may be larger than the area of ​​the second division. The second division arranged closer to the outer periphery of the light absorbing film than the first division is closer to the boundary between the light absorbing film and another member, and therefore receives a larger stress when a temperature difference occurs than the first division. However, by doing so, damage such as peeling of the light absorbing film to another member can be suppressed in the region where the stress is large when a temperature difference occurs. Therefore, the yield can be improved more efficiently.

[0015] (4) In the above (1) or (2), the multiple divisions may each have the same shape when viewed in a direction perpendicular to the first main surface. This configuration can reduce stress when a large temperature difference occurs across the entire light absorbing film. Therefore, the yield can be improved more reliably.

[0016] (5) In any of the above (1) to (4), the groove may penetrate the light absorbing film in the thickness direction. In this way, the adjacent divided parts can be completely separated by the groove. Therefore, it is possible to further reduce the stress generated in the light absorbing film when a large temperature difference occurs. Therefore, it is possible to more reliably improve the yield.

[0017] (6) In any of the above (1) to (5), the recessed groove may include a plurality of first groove-shaped portions extending in a first direction and spaced apart in a second direction intersecting the first direction, and a plurality of second groove-shaped portions extending in the second direction and spaced apart in the first direction. A light absorbing film having such a configuration can have a relatively simple shape, and stress can be relieved evenly throughout the light absorbing film.

[0018] (7) In any of the above (1) to (6), the outer shape of each of the divided parts may be a square when viewed in a direction perpendicular to the first main surface. The length of one side of the square may be 0.1 mm or more and 0.5 mm or less. This makes it possible to more reliably relieve stress generated in each divided part while preventing the divided parts from becoming complicated in shape, thereby improving productivity.

[0019] (8) In any of the above (1) to (6), the thickness of the light absorbing film may be 3 μm or more. The light absorbing film may have an absorptivity of 75% or more for light having a wavelength of 8 μm. This makes it possible to more reliably maintain a high light absorptivity while realizing a low thermal conductivity.

[0020] (9) In any of the above (1) to (8), the carbon content may be 60% by mass or more and 95% by mass or less. The resin content may be 5% by mass or more and 40% by mass or less. The light absorbing film having such a configuration contains the resin at a content rate of 5% by mass or more and 40% by mass or less, and therefore can more reliably reduce thermal conductivity. In other words, the light absorbing film having the above configuration can achieve high light absorptivity while reducing thermal conductivity.

[0021] (10) In any one of the above (1) to (9), the thermal conductivity of the light absorbing film may be 1 W / mK or less. Such an optical sensor can more reliably form a large temperature difference and further improve sensitivity.

[0022] (11) In any one of the above (1) to (10), the resin may include an epoxy resin. Such an optical sensor can more reliably achieve low thermal conductivity and high light absorptance in the light absorbing film, thereby more reliably improving sensitivity.

[0023] (12) In any of the above (1) to (11), the thickness of the light absorbing film may be 2 μm or more and 7 μm or less. This makes it possible to more reliably achieve a large temperature difference by preventing the light absorbing film from becoming too thick while reliably maintaining the light absorption performance of the light absorbing film.

[0024] (13) In any of the above (1) to (12), the outer shape of the light absorbing film may be rectangular when viewed in a direction perpendicular to the first main surface. Each p-type material layer and each n-th material layer may be arranged so that the longitudinal direction is along the direction in which one side of the light absorbing film extends or the direction perpendicular to the direction in which one side extends. In this way, when the support layer is rectangular when viewed in a direction perpendicular to the first main surface, it is possible to effectively utilize the area on the first main surface and form a large temperature difference in the longitudinal direction of the strip-shaped p-type material layer and the longitudinal direction of the strip-shaped n-type material layer. Therefore, it is possible to further improve the sensitivity.

[0025] (14) In any of the above (1) to (13), the first region and the third region may be electrically connected via a first connecting portion having electrical conductivity, and the second region and the fourth region may be electrically connected via a second connecting portion having electrical conductivity. In this way, the p-type material layer and the n-type material layer can be reliably electrically connected by the first connecting portion and the second connecting portion. In addition, since the p-type material layer and the n-type material layer do not overlap each other, the p-type material layer and the n-type material layer can be easily formed by film formation or the like in the same process. Therefore, productivity can be improved.

[0026] (15) In any of the above (1) to (13), the multiple p-type material layers and the multiple n-type material layers may be configured such that the first region and the third region overlap when viewed in a direction perpendicular to the first main surface, and are connected in ohmic contact, and the second region and the fourth region overlap when viewed in a direction perpendicular to the first main surface, and are connected in ohmic contact. This makes it easy to arrange the p-type material layers and the n-type material layers in a concentrated manner on the first main surface without interposing a member between the p-type material layers and the n-type material layers. Therefore, it is easy to arrange many p-type material layers and n-type material layers and increase the output.

[0027] (16) In any of the above (1) to (15), at least one of the p-type material layer and the n-type material layer may be made of SiGe having at least one of a nanocrystalline structure and an amorphous structure with a grain size of 3 nm to 200 nm. This can improve the thermoelectric conversion efficiency and therefore the sensitivity.

[0028] (17) In any of the above (1) to (15), the SiGe may be polycrystalline. Such polycrystalline SiGe is also suitably used in the optical sensor of the present disclosure. The crystallization rate of the polycrystalline material of the present disclosure is 99% or more.

[0029] [Details of the embodiment of the present disclosure] Next, an embodiment of the optical sensor of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference characters and the description thereof will not be repeated.

[0030] (Embodiment 1) The configuration of the optical sensor according to the first embodiment of the present disclosure will be described. FIG. 1 is a schematic plan view of the appearance of the optical sensor in the first embodiment. FIG. 2 is a schematic plan view showing a state in which an infrared absorbing film as a light absorbing film and an insulating film, which will be described later, are removed from the optical sensor shown in FIG. 1. FIG. 3 is a schematic cross-sectional view of the optical sensor of the first embodiment, showing a cross-section along line III-III in FIG. 1. FIG. 4 is an enlarged view of a portion indicated by region IV in FIG. 1. FIG. 5 is a schematic cross-sectional view of the optical sensor of the first embodiment, showing a cross-section along line VV in FIG. 4.

[0031] 1, 2, 3, 4, and 5, the optical sensor 11a is, for example, an infrared sensor. The optical sensor 11a includes a support layer 12, a thermoelectric conversion material part 13, a heat sink 14, an infrared absorbing film 15a as a light absorbing film, an insulating film 16, a first electrode 17, and a second electrode 18. The support layer 12 is a thin layer. In this embodiment, the support layer 12 is rectangular when viewed in the thickness direction. Specifically, the length of the support layer 12 in the Y direction is longer than the length of the support layer 12 in the X direction. The X direction and the Y direction are directions perpendicular to the Z direction, which is the thickness direction of the support layer 12. The X direction and the Y direction are perpendicular to each other.

[0032] The support layer 12 has a first main surface 21 and a second main surface 22. The first main surface 21 is a main surface on which the thermoelectric conversion material portion 13 is formed, and the second main surface 22 is a main surface located opposite the first main surface 21. In other words, the first main surface 21 and the second main surface 22 are arranged with an interval in the Z direction, which is the thickness direction of the support layer 12. As a material for the support layer 12, for example, SiO2 (silicon dioxide) or SiN (silicon nitride) is selected.

[0033] The thermoelectric conversion material section 13 converts thermal energy (temperature difference) into electrical energy. The thermoelectric conversion material section 13 is disposed on the support layer 12, specifically on the first main surface 21. The thermoelectric conversion material section 13 includes a plurality of strip-shaped p-type material layers 23 and a plurality of strip-shaped n-type material layers 24. The p-type material layer 23 is made of SiGe (silicon germanium) having a p-type conductivity. The n-type material layer 24 is made of SiGe (silicon germanium) having an n-type conductivity. A pair of thermocouples is formed by combining one p-type material layer 23 and one n-type material layer 24. The number of p-type material layers 23 and the number of n-type material layers 24 are arbitrarily determined according to the required function, application, and the like. The configurations of the plurality of p-type material layers 23 and the plurality of n-type material layers 24 will be described in detail later.

[0034] The heat sink 14 is disposed on the support layer 12, specifically on the second main surface 22. The heat sink 14 is configured to be sufficiently thick compared to the support layer 12 and the like. The heat sink 14 has a recess 25 on the inside when viewed in the Z direction, which is a direction perpendicular to the first main surface 21. The edge 26 of the recess 25 is rectangular when viewed in the Z direction. The recess 25, together with an infrared absorbing film 15a described later, is provided so as to form a temperature difference in the longitudinal direction of the strip-shaped p-type material layer 23 and the longitudinal direction of the strip-shaped n-type material layer 24 disposed on the first main surface 21 of the support layer 12. For example, Si (silicon) is selected as the material of the heat sink 14. In this embodiment, the heat sink 14 is configured from a silicon substrate.

[0035] The infrared absorbing film 15a is disposed in a region where the recesses 25 are formed when viewed in a direction perpendicular to the first main surface 21. That is, the infrared absorbing film 15a is disposed in a region where the recesses 25 are located when viewed in the Z direction, which is a direction perpendicular to the first main surface 21. An outer edge 27 of the infrared absorbing film 15a is rectangular when viewed in the Z direction. The configuration of the infrared absorbing film 15a will be described in detail later.

[0036] The insulating film 16 is disposed between the thermoelectric conversion material section 13 and the infrared absorbing film 15a. The insulating film 16 ensures insulation between the thermoelectric conversion material section 13 and the infrared absorbing film 15a. The insulating film 16 is in contact with the support layer 12 in an area where the thermoelectric conversion material section 13 is not disposed. The outer edge 28 of the insulating film 16 is also rectangular when viewed in the Z direction, similar to the outer edge 27 of the infrared absorbing film 15a. For example, SiO2 is selected as the material of the insulating film 16. The thickness of the insulating film 16 is selected to be 10 nm or more and 300 nm or less.

[0037] The first electrode 17 and the second electrode 18 are disposed on the first main surface 21 of the support layer 12. Two first electrodes 17 and two second electrodes 18 are provided. The first electrodes 17 and the second electrodes 18 are each so-called pad electrodes. The two first electrodes 17 are each connected to one of the p-type material layers 23 among the plurality of p-type material layers 23. The two second electrodes 18 are each connected to one of the n-type material layers 24 among the plurality of n-type material layers 24. For example, Au (gold), Ti (titanium), and Pt (platinum) are selected as the material of the first electrode 17 and the second electrode 18. The first electrode 17 and the second electrode 18 are each electrically connected to the outside.

[0038] Next, a specific configuration of the thermoelectric conversion material section 13 will be described. Each of the multiple p-type material layers 23 includes a first region 31 that overlaps with the heat sink 14 when viewed in a direction perpendicular to the first main surface 21, and a second region 32 that overlaps with the infrared absorbing film 15a. The first region 31 includes a first end 41 located on one side in the longitudinal direction of the p-type material layer. The second region 32 includes a second end 42 located on the other side in the longitudinal direction of the p-type material layer. Each of the multiple n-type material layers includes a third region 33 that overlaps with the heat sink 14 when viewed in a direction perpendicular to the first main surface 21, and a fourth region 34 that overlaps with the infrared absorbing film 15a. As described below, the first region 31 and the third region 33 are regions that overlap with the heat sink 14 when viewed in a direction perpendicular to the first main surface 21, and are electrically connected to each other. The second region 32 and the fourth region 34 overlap with the infrared absorbing film 15a when viewed in a direction perpendicular to the first main surface 21, and are electrically connected to each other. The third region 33 includes a third end 43 located on one side in the longitudinal direction of the n-type material layer 24. The fourth region 34 includes a fourth end 44 located on the other side in the longitudinal direction of the n-type material layer 24.

[0039] In this embodiment, each p-type material layer 23 and each n-type material layer 24 is arranged so that the longitudinal direction is along the extending direction of one side of the infrared absorbing film 15a or a direction perpendicular to the extending direction of one side. Specifically, each p-type material layer 23 and each n-type material layer 24 is arranged so that the longitudinal direction is the X direction or the Y direction.

[0040] The thermoelectric conversion material portion 13 also includes a plurality of first connection portions 35 having electrical conductivity and a plurality of second connection portions 36 having electrical conductivity. The first connection portion 35 and the second connection portion 36 are each rectangular when viewed in the Z direction. The first connection portion 35 connects the first region 31 and the third region 33. That is, the first region 31 and the third region 33 are electrically connected via the first connection portion 35. The second connection portion 36 connects the second region 32 and the fourth region 34. That is, the second region 32 and the fourth region 34 are electrically connected via the second connection portion 36. For example, the same material as that of the first electrode 17 and the second electrode 18 is selected as the material of the first connection portion 35 and the second connection portion 36. The first region 31 and the third region 33 are each a region in ohmic contact with the first connection portion 35. In this manner, the first region 31 and the third region 33 are electrically connected. The second region 32 and the fourth region 34 are each in ohmic contact with the second connecting portion 36. In this manner, the second region 32 and the fourth region 34 are electrically connected to each other.

[0041] The first region 31 and the third region 33 of each of the multiple p-type material layers 23 and the multiple n-type material layers 24 are electrically connected via a first connection portion 35. Also, the second region 32 and the fourth region 34 of each of the multiple p-type material layers 23 and the multiple n-type material layers 24 are electrically connected via a second connection portion 36. In this manner, the multiple p-type material layers 23 and the multiple n-type material layers 24 are alternately arranged in series.

[0042] Here, a specific configuration of the infrared absorbing film 15a will be described. The infrared absorbing film 15a is composed of carbon and resin. In this embodiment, the infrared absorbing film 15a is composed of 60% by mass or more and 95% by mass or less of carbon and 5% by mass or more and 40% by mass or less of resin. Specifically, for example, the infrared absorbing film 15a is composed of 85% by mass of carbon and 15% by mass of resin. As a specific resin, for example, epoxy resin is selected. The thermal conductivity of the infrared absorbing film 15a is 1 W / mK or less. In this embodiment, the thermal conductivity of the infrared absorbing film 15a is 0.6 W / mK. In addition, the thickness T1 of the infrared absorbing film 15a is 2 μm or more and 7 μm or less. In this embodiment, the thickness T1 of the infrared absorbing film 15a is 5 μm.

[0043] The infrared absorbing film 15a is divided into a plurality of divisions 52a by grooves 51a recessed in the thickness direction (Z direction). In this embodiment, the infrared absorbing film 15a has a rectangular outer shape when viewed in a direction perpendicular to the first main surface 21. The plurality of divisions 52a each have a rectangular outer shape. The plurality of divisions 52a each have the same shape when viewed in a direction perpendicular to the first main surface 21. Specifically, the plurality of divisions 52a each have a square outer shape when viewed in a direction perpendicular to the first main surface 21. The length of one side of the square is 0.1 mm or more and 0.5 mm or less. The plurality of divisions 52a are arranged over the entire infrared absorbing film 15a.

[0044] The groove 51a includes a plurality of first groove-shaped portions 53a that extend in the X direction, which is a first direction, and are arranged at intervals in the Y direction, which is a second direction that intersects with the X direction and is perpendicular to the X direction in this embodiment, and a plurality of second groove-shaped portions 54a that extend in the Y direction and are arranged at intervals in the X direction. That is, the plurality of division portions 52a are divided by the first groove-shaped portions 53a and the second groove-shaped portions 54a. The groove 51a penetrates the infrared absorbing film 15a in the thickness direction.

[0045] The optical sensor 11a can be manufactured, for example, as follows. The manufacturing method of the optical sensor 11a having the above configuration will be briefly described below. First, a silicon substrate is prepared, and a film of SiO2 or SiN that becomes the support layer 12 is formed on the silicon substrate. Then, a film of SiGe that constitutes the p-type material layer 23 and the n-type material layer 24 included in the thermoelectric conversion material portion 13 is formed, and the first connection portion 35 and the second connection portion 36, and the first electrode 17 and the second electrode 18 are formed by film formation in order to electrically connect each material layer. For example, Ni (nickel), Ti (titanium), or Au (gold) is selected as the material of the first connection portion 35 and the second connection portion 36. The material of the first electrode 17 and the second electrode 18 is as described above. Then, the insulating film 16 is formed by SiO2, and the infrared absorbing film 15a is formed.

[0046] Regarding the formation of the infrared absorbing film 15a, first, a black resist is prepared, and this is applied by a spin coater to form a film. The black resist is prepared by blending various components, for example, a solvent, so that the infrared absorbing film 15a consisting of 60% by mass or more and 95% by mass or less of carbon and 5% by mass or more and 40% by mass or less of resin is finally left. In this case, for example, bisphenol A type epoxy resin may be used as the epoxy resin. After the film formation, the black resist is exposed by a photolithography device and immersed in a developer to form a pattern. In this case, the outer shape is formed to be rectangular, and the above-mentioned multiple recessed grooves 51a extending in the X direction and multiple recessed grooves 51a extending in the Y direction are formed. Finally, post-baking is performed to complete the film formation. Thereafter, the silicon substrate is etched so as to penetrate the silicon substrate and reach the support layer 12, forming recesses 25 and the like, thereby forming the heat sink 14, and the optical sensor 11a having the above configuration is manufactured.

[0047] According to such an optical sensor 11a, since the insulating film 16 is disposed between the thermoelectric conversion material section 13 and the infrared absorbing film 15a, it is possible to ensure insulation between the thermoelectric conversion material section 13 and the infrared absorbing film 15a. In addition, since the infrared absorbing film 15a that forms a temperature difference between each of the strip-shaped p-type material layers 23 and the strip-shaped n-type material layers 24 included in the thermoelectric conversion material section 13 is made of carbon and resin, it is possible to realize a high light absorption rate while reducing the thermal conductivity. In other words, it is possible to achieve both low thermal conductivity and high light absorption rate. Therefore, it is possible to improve the sensitivity. Furthermore, since the infrared absorbing film 15a is divided into a plurality of division parts 52a by the grooves 51a, it is possible to alleviate the stress generated in the infrared absorbing film 15a when a high temperature difference occurs. Therefore, even if a high temperature difference occurs, it is possible to suppress damage to the infrared absorbing film 15a. As a result, it is possible to improve the yield of the optical sensor 11a. As described above, according to such an optical sensor 11a, it is possible to improve the sensitivity and the yield rate.

[0048] In this embodiment, the outer shape of the infrared absorbing film 15a is rectangular when viewed in a direction perpendicular to the first main surface 21. The outer shapes of the multiple divisions 52a are each rectangular. Therefore, the multiple divisions 52a can be arranged along the overall outer shape of the infrared absorbing film 15a, and damage to the infrared absorbing film 15a when a high temperature difference occurs can be more reliably suppressed. Therefore, the yield can be more reliably improved.

[0049] In this embodiment, the multiple divisions 52a have the same shape when viewed in a direction perpendicular to the first main surface 21. The multiple divisions 52a are arranged over the entire infrared absorbing film 15a. This configuration can reduce stress when a high temperature difference occurs over the entire infrared absorbing film 15a. Therefore, the yield can be improved more reliably.

[0050] In this embodiment, the groove 51a penetrates the infrared absorbing film 15a in the thickness direction. Therefore, the adjacent division parts 52a can be completely separated by the groove 51a. Therefore, it is possible to further reduce the stress generated in the infrared absorbing film 15a when a large temperature difference occurs. Therefore, it is possible to more reliably improve the yield.

[0051] In this embodiment, the recessed groove 51a includes a plurality of first groove-shaped portions 53a extending in a first direction and arranged at intervals in a second direction intersecting the first direction, and a plurality of second groove-shaped portions 54a extending in the second direction and arranged at intervals in the first direction. The infrared absorbing film 15a having such a configuration can be made to have a relatively simple shape, and stress can be relieved evenly throughout the infrared absorbing film 15a.

[0052] In this embodiment, the outer shape of each of the divided portions 52a is a square when viewed in a direction perpendicular to the first main surface 21. The length of one side of the square is 0.1 mm or more and 0.5 mm or less. With this configuration, it is possible to more reliably relieve the stress generated in each divided portion 52a while preventing the divided portion 52a from becoming a complicated shape, thereby improving productivity.

[0053] In this embodiment, the outer shape of the infrared absorbing film 15a is rectangular when viewed in a direction perpendicular to the first main surface 21. Each p-type material layer 23 and each n-th material layer 24 are arranged so that their longitudinal direction is along the extending direction of one side of the infrared absorbing film 15a or a direction perpendicular to the extending direction of one side. Therefore, when the support layer 12 is rectangular when viewed in a direction perpendicular to the first main surface 21, it is possible to effectively utilize the area on the first main surface 21 to form a large temperature difference in the longitudinal direction of the strip-shaped p-type material layer 23 and the longitudinal direction of the strip-shaped n-type material layer 24. Therefore, it is possible to further improve the sensitivity.

[0054] In this embodiment, the first region 31 and the third region 33 are electrically connected via a first conductive member having conductivity, and the second region 32 and the fourth region 34 are electrically connected via a second connecting portion 36 having conductivity. Therefore, the first connecting portion 35 and the second connecting portion 36 can reliably electrically connect the p-type material layer 23 and the n-type material layer 24. In addition, since the p-type material layer 23 and the n-type material layer 24 are configured not to overlap each other, the p-type material layer 23 and the n-type material layer 24 can be easily formed by film formation or the like in the same process. Therefore, the productivity can be improved.

[0055] A heat cycle test (compliant with MIL-STD-883 Method 1010 condition C) was conducted on the optical sensor 11a having the above configuration to perform a reliability test. A TSA-73ES-W (manufactured by Espec Corporation) was used as the device, and the temperature conditions were -65°C (30 minutes) and 150°C (30 minutes) as one cycle, and 10 cycles were repeated in total. After the test, the sample was taken out and the current-voltage characteristics and sensitivity were evaluated to evaluate whether there was any disconnection or deterioration in sensitivity, thereby evaluating the yield after the reliability test. The same test was also conducted on an optical sensor (hereinafter sometimes referred to as a "conventional optical sensor") that does not have a groove 51a, that is, includes an infrared absorbing film without a dividing portion.

[0056] In conventional optical sensors, after heat cycle testing, there were many cases of damage caused by the infrared absorbing film peeling off from the boundary between the silicon substrate and the infrared absorbing film (the edge of the membrane structure), and disconnections caused by the thermoelectric conversion material overlapping the infrared absorbing film being peeled off, and the yield did not reach 30%.

[0057] In contrast, with the optical sensor of embodiment 1, the probability of the above-mentioned damage or disconnection occurring was low, and the yield was 95%, nearly 100%.

[0058] Here, a CAE (Computer Aided Engineering) analysis of stress was performed for the conventional optical sensor and the optical sensor of the first embodiment. Figures 6 and 7 are analysis results of a model of the conventional optical sensor. Figures 6 and 7 show the displacement of the support layer at -65°C and 350°C, respectively. Figures 8 and 9 are analysis results of a model of the optical sensor of the first embodiment. Figures 8 and 9 are schematic diagrams showing the displacement of the infrared absorbing film at -65°C and 350°C, respectively. In Figures 6, 7, 8, and 9, the Z direction indicates the thickness direction of the infrared absorbing film. The rectangular shape as viewed from the Z direction indicates, from the inside, the end of the infrared absorbing film and the boundary between the heat sink and the support layer. The displacement is illustrated in five stages (for example, in Figure 6, region 61a, region 62a, region 63a, region 64a, and region 65a).

[0059] 10 and 11 are graphs showing the displacement amount and its position of the support layer at −65° C. and 350° C. in a model of a conventional optical sensor. FIG. 12 and FIG. 13 are graphs showing the displacement amount and its position of the support layer at −65° C. and 350° C. in a model of an optical sensor according to the first embodiment. In FIG. 10, the vertical axis shows the displacement amount (mm), and the horizontal axis shows the position (mm). On the horizontal axis, the position shown by 0 mm is the center of the infrared absorbing film, the position shown by 0.375 mm is the end of the infrared absorbing film, and the position shown by 0.6 mm is the end of the support layer (the boundary with the heat sink). The same applies to the vertical and horizontal axes in the graphs shown in FIG. 11, FIG. 12, and FIG. 13.

[0060] First, referring to FIG. 6 and FIG. 10, the displacement increases in the order of region 61a, region 62a, region 63a, region 64a, and region 65a. At −65° C., the central region of the infrared absorbing film 56a in the conventional optical sensor is recessed in the thickness direction, and the displacement reaches 0.025 mm. It can be seen that the displacement increases at low temperatures for the conventional optical sensor. Referring to FIG. 7 and FIG. 11, the displacement increases in the order of region 61b, region 62b, region 63b, region 64b, and region 65b. At 350° C., the central region of the infrared absorbing film 56b in the conventional optical sensor is raised in the thickness direction, and the displacement reaches 0.090 mm. It can be seen that the displacement increases extremely at high temperatures for the conventional optical sensor.

[0061] Next, referring to FIG. 8 and FIG. 12, the displacement increases in the order of region 61c, region 62c, region 63c, region 64c, and region 65c. At −65° C., the central region of the infrared absorbing film 56c in the optical sensor of embodiment 1 is recessed in the thickness direction, but the displacement is at most 0.0083 mm. It can be seen that the displacement of the optical sensor of embodiment 1 is not larger than that of the conventional optical sensor at low temperatures. Referring to FIG. 9 and FIG. 13, the displacement increases in the order of region 61d, region 62d, region 63d, region 64d, and region 65d. At 350° C., the central region of the infrared absorbing film 56d in the optical sensor of embodiment 1 is raised in the thickness direction, but the displacement is at most 0.030 mm. It can be seen that the displacement of the optical sensor of embodiment 1 at high temperatures is about 1 / 3 of that of the conventional optical sensor, and the displacement is not larger than that of the conventional optical sensor.

[0062] FIG. 14 is a schematic diagram showing stress generated in an infrared absorbing film in a CAE analysis of stress in a model of a conventional optical sensor. FIG. 15 is a schematic diagram showing stress generated in an infrared absorbing film in a CAE analysis of stress in a model of an optical sensor of the first embodiment. FIG. 14 and FIG. 15 are views seen in the thickness direction of the infrared absorbing film. In FIG. 14 and FIG. 15, the stress generated in the boundary portion between the silicon substrate and the support layer is shown by lines 57e and 57f, and the stress generated in the boundary portion between the support layer and the infrared absorbing film is shown by lines 58e and 58f. In FIG. 15, the infrared absorbing film is divided into a plurality of division portions by a plurality of grooves 51a, so that a plurality of lines 58f are formed. Note that, from the viewpoint of facilitating understanding, only lines extending in the X direction are shown, and lines extending in the Y direction are not shown.

[0063] First, referring to FIG. 14, in the conventional optical sensor 56e, the line 57e is generated at two places in the vertical direction (Y direction), and a strong stress F1 equivalent to 66 MPa is applied to each of the lines. Also, the line 58e is generated at two places in the vertical direction, and a strong stress F2 equivalent to 61 MPa is applied to each of the lines. In contrast, referring to FIG. 15, in the optical sensor 56f of the first embodiment, a plurality of stresses F2, specifically, a stress equivalent to the number of the recessed grooves 51a, are generated for the line 58f. It can be seen that the stresses F2 are equivalent to 39 MPa, and are reduced by about 63% compared to the case of the conventional optical sensor. Also, it can be seen that the stress F1 shown in the line 57f is equivalent to 24 MPa, and are reduced by about 36% compared to the case of the conventional optical sensor.

[0064] (Embodiment 2) Another embodiment, embodiment 2, will now be described. Fig. 16 is a schematic plan view of the exterior of an infrared absorbing film 15b included in an optical sensor according to embodiment 2 of the present disclosure. The optical sensor according to embodiment 2 basically has the same configuration as in embodiment 1, and achieves the same effects. However, the optical sensor according to embodiment 2 differs from embodiment 1 in the configuration of the infrared absorbing film 15b.

[0065] With reference to FIG. 16, the infrared absorbing film 15b included in the optical sensor in the second embodiment is made of carbon and resin, and is divided into a plurality of divisions by a groove 51a recessed in the thickness direction. Unlike the first embodiment, the plurality of divisions includes a first division 71b arranged in the center of the infrared absorbing film 15b, and a second division 72b arranged closer to the outer periphery of the infrared absorbing film 15b than the first division 71b, as viewed in a direction perpendicular to the first main surface. The area of ​​the first division 71b is larger than the area of ​​the second division 72b. A plurality of second divisions 72b are provided along the outer periphery of the first division 71b. In this embodiment, the second divisions 72b are provided around the outer periphery of the first division 71b for two revolutions. The second divisions 72b are not limited to two revolutions, and may be provided for three or more revolutions.

[0066] According to the optical sensor including the infrared absorbing film 15b of this embodiment, the first divided portion 71b, which has an area larger than that of the second divided portion 72b, can efficiently absorb light. Furthermore, the second divided portion 72b, which has an area smaller than that of the first divided portion 71b, can relieve the stress of the infrared absorbing film 15b and reduce the risk of damage or breakage at the outer periphery of the infrared absorbing film 15b. Therefore, it is possible to improve the yield while further improving the sensitivity.

[0067] (Embodiment 3) Another embodiment, that is, embodiment 3, will be described. Fig. 17 is a schematic plan view of the appearance of the infrared absorbing film 15c included in the optical sensor in embodiment 3 of the present disclosure. The optical sensor in embodiment 3 basically has the same configuration as in embodiment 2 and achieves the same effects. However, the optical sensor in embodiment 3 differs from embodiment 2 in the configuration of the infrared absorbing film 15c.

[0068] With reference to FIG. 17, the infrared absorbing film 15c included in the optical sensor in the third embodiment is made of carbon and resin, and is divided into a plurality of divisions by a groove recessed in the thickness direction. Unlike the first embodiment, the plurality of divisions includes a first division 71c arranged in the center of the infrared absorbing film 15c, and a second division 72c arranged closer to the outer periphery of the infrared absorbing film 15c than the first division 71c, as viewed in a direction perpendicular to the first main surface. The area of ​​the first division 71c is larger than the area of ​​the second division 72c. A plurality of second divisions 72c are provided along the outer periphery of the first division 71c. In this embodiment, the second division 72c is provided around the outer periphery of the first division 71c.

[0069] According to the optical sensor including the infrared absorbing film 15c of this embodiment, the first division 71c, which has an area larger than that of the second division 72c, can efficiently absorb light. Furthermore, the second division 72c, which has an area smaller than that of the first division 71c, can relieve the stress of the infrared absorbing film 15c and reduce the risk of damage or breakage at the outer periphery of the infrared absorbing film 15c. Therefore, it is possible to improve the yield while further improving the sensitivity.

[0070] (Embodiment 4) Another embodiment, that is, embodiment 4, will be described. Fig. 18 is a schematic plan view of the appearance of an infrared absorbing film 15d included in an optical sensor according to embodiment 4 of the present disclosure. The optical sensor according to embodiment 4 basically has the same configuration as in embodiment 1, and exerts the same effects. However, the optical sensor according to embodiment 4 differs from embodiment 1 in the configuration of the infrared absorbing film 15d.

[0071] 18, the infrared absorbing film 15d included in the optical sensor in the fourth embodiment is made of carbon and resin, and is divided into a plurality of divisions 52d by a groove 51a recessed in the thickness direction. Unlike the first embodiment, the plurality of divisions 52d are divided by one groove 51a extending in the X direction and one groove 51a extending in the Y direction when viewed in a direction perpendicular to the first main surface. Specifically, the infrared absorbing film 15d included in the optical sensor in the fourth embodiment is divided into four divisions 52d of the same shape and size. This also makes it possible to improve the yield while improving the sensitivity.

[0072] (Embodiment 5) Another embodiment, embodiment 5, will be described. Fig. 19 is a schematic plan view of the appearance of an infrared absorbing film 15e included in an optical sensor in embodiment 5 of the present disclosure. The optical sensor in embodiment 5 basically has the same configuration as in embodiment 1 and achieves the same effects. However, the optical sensor in embodiment 5 differs from embodiment 1 in the configuration of the infrared absorbing film 15e.

[0073] Referring to FIG. 19, the infrared absorbing film 15e included in the optical sensor in the fifth embodiment is made of carbon and resin, and is divided into a plurality of divisions 52e by grooves 51a recessed in the thickness direction. Unlike the first embodiment, the infrared absorbing film 15e has a circular outer shape when viewed in a direction perpendicular to the first main surface. The grooves 51a are provided in a lattice pattern as in the first embodiment. In this case, for example, the plurality of P-type material layers and the plurality of n-type material layers may be arranged radially. This also improves the yield while improving the sensitivity.

[0074] (Other embodiments) In the above embodiment, the groove penetrates the infrared absorbing film in the thickness direction, but the groove may not penetrate the infrared absorbing film in the thickness direction. That is, the groove is made of the infrared absorbing film, and as an example, the thickness of the groove may be 20% of the thickness of the infrared absorbing film in the division part. This configuration also reduces the stress generated in the infrared absorbing film compared to a configuration in which the infrared absorbing film is uniformly formed without the groove.

[0075] In the above embodiment, the thickness of the infrared absorbing film may be 3 μm or more. The absorptivity of the light absorbing film for light with a wavelength of 8 μm may be 75% or more. In this way, it is possible to more reliably maintain high light absorptivity while realizing low thermal conductivity.

[0076] In the above embodiment, the carbon content may be 60% by mass or more and 95% by mass or less. The resin content may be 5% by mass or more and 40% by mass or less. The infrared absorbing film having such a configuration contains the resin at a content rate of 5% by mass or more and 40% by mass or less, so that the thermal conductivity can be more reliably reduced. That is, the infrared absorbing film having the above configuration can achieve high light absorptivity while reducing thermal conductivity.

[0077] In the above-described embodiment, the thermal conductivity of the infrared absorbing film may be equal to or less than 1 W / mK. Such an optical sensor can more reliably generate a large temperature difference, thereby improving the sensitivity.

[0078] In the above embodiment, the resin may include an epoxy resin. Such an optical sensor can more reliably achieve low thermal conductivity and high light absorptance in the light absorbing film, and therefore can more reliably improve the sensitivity.

[0079] In the above embodiment, the thickness of the infrared absorbing film may be 2 μm or more and 7 μm or less, thereby preventing the infrared absorbing film from becoming too thick more than necessary while reliably maintaining the light absorption performance of the infrared absorbing film, thereby more reliably realizing a large temperature difference.

[0080] In the above embodiment, the plurality of p-type material layers and the plurality of n-type material layers may be connected in ohmic contact with each other such that the first region and the third region overlap when viewed in a direction perpendicular to the first main surface, and the second region and the fourth region overlap when viewed in a direction perpendicular to the first main surface, and the second region and the fourth region overlap when viewed in a direction perpendicular to the first main surface, and the second region and the fourth region overlap when viewed in a direction perpendicular to the first main surface. In this way, it is easy to arrange the p-type material layers and the n-type material layers in a concentrated manner on the first main surface without interposing a member between the p-type material layers and the n-type material layers. Therefore, it is easy to increase the output by arranging many p-type material layers and n-type material layers.

[0081] In the above embodiment, at least one of the p-type material layer and the n-type material layer may be made of SiGe having at least one of a nanocrystalline structure and an amorphous structure with a grain size of 3 nm to 200 nm. In this way, the thermoelectric conversion efficiency can be improved. Therefore, the sensitivity can be improved.

[0082] The grain size of the crystals was measured by observing TEM (Transmission Electron Microscope) images. The device used was a JEM-2100F (manufactured by JEOL Ltd.), and the acceleration voltage was set to 200 kV. The electron probe diameter was set to 0.2 nm, and the EDX mapping conditions were set to 256 pixels x 256 pixels, 0.5 ms / pixel, and 15 times of accumulation.

[0083] In addition, for SiGe, which is a constituent material of the p-type material layer and the n-type material layer, a nanocrystalline structure may be created in a part of amorphous SiGe by heat-treating the SiGe at a temperature of, for example, about 500°C. In addition, SiGe may be polycrystalline. Such polycrystalline SiGe is also preferably used in the optical sensor of the present disclosure. The crystallization rate of the polycrystalline body in the optical sensor of the present disclosure is 99% or more. The crystallization rate was measured as follows. The apparatus used was a HORIBA LabRam HR-PL. The measurement conditions were a laser wavelength of 532 nm and a laser power of 2.5 mW. The analysis conditions were a 400 cm -1 The peaks around were analyzed. In the analysis, a Gaussian function and a pseudo-Voigt function were fitted. The Gaussian function G(x) is expressed by the following formula 2.

[0084]

number

[0085] Moreover, the pseudo-Voigt function F(x) is expressed by the following formula 3.

[0086]

number

[0087] Gaussian function G(x): variable A g , W g , x g In this example, the initial value of x0 is 400 cm -1 The pseudo-Voigt function F(x): variable A f , W f , x f , m, the initial value of x0 is 380 cm -1and g was set to 0.5. Each parameter was optimized by the least squares method, and the pseudo-Voigt function and Gaussian function were integrated to determine the area. The crystallinity ratio was calculated by the formula: crystallinity ratio = area derived using the pseudo-Voigt function / (area derived using the pseudo-Voigt function + area derived using the Gaussian function), assuming that the area derived using the Gaussian function corresponds to amorphous and the area derived using the pseudo-Voigt function corresponds to crystal.

[0088] It should be understood that the embodiments disclosed herein are illustrative in all respects and are not limiting in any respect. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0089] 11a, 56e, 56f Optical sensors 12 Support layer 13 Thermoelectric Materials Department 14 Heat sink 15a, 15b, 15c, 15d, 15e, 56a, 56b, 56c, 56d Infrared absorbing film (light absorbing film) 16 Insulating film 17 1st electrode 18 2nd electrode 21 First main surface 22 Second main surface 23 p-type material layer 24 n-type material layers 25 Recess 26 Relationship 27,28 Outer edge 31 First area 32 Second area 33 Third area 34 4th area 35 First connection part 36 Second connection part 41 First end 42 Second end 43 Third end 44 4th end 51a, 53d, 54d concave grooves 52a, 52d, 52e dividing parts 53a first groove-shaped part 54a second groove-shaped part 57e, 57f, 58e, 58f lines 61a, 61b, 61c, 61d, 62a, 62b, 62c, 62d, 63a, 63b, 63c, 63d, 64a, 64b, 64c, 64d, 65a, 65b, 65c, 65d regions 71b, 71c first dividing part 72b, 72c second dividing part F1, F2 stresses

Claims

1. A support layer having a first main surface and a second main surface located opposite the first main surface in a thickness direction; a thermoelectric conversion material portion disposed on the first main surface, the thermoelectric conversion material portion including: a plurality of strip-shaped p-type material layers made of SiGe having a p-type conductivity and converting thermal energy into electrical energy; and a plurality of strip-shaped n-type material layers made of SiGe having an n-type conductivity and converting thermal energy into electrical energy; a heat sink disposed on the second main surface and having a recess on an inner side when viewed in a direction perpendicular to the first main surface; a light absorbing film arranged to overlap the recess when viewed in a direction perpendicular to the first main surface; an insulating film disposed between the thermoelectric conversion material portion and the light absorbing film, each of the plurality of p-type material layers includes a first region overlapping the heat sink and a second region overlapping the light absorbing film when viewed in a direction perpendicular to the first main surface; each of the plurality of n-type material layers includes a third region overlapping the heat sink and a fourth region overlapping the light absorbing film when viewed in a direction perpendicular to the first main surface; the plurality of p-type material layers and the plurality of n-type material layers are alternately arranged in series such that the first region and the third region are electrically connected and the second region and the fourth region are electrically connected; The light absorbing film is made of carbon and resin, The light absorbing film is divided into a plurality of divisions by grooves recessed in a thickness direction of the light sensor.

2. When viewed in a direction perpendicular to the first main surface, The outer shape of the light absorbing film is rectangular, The optical sensor according to claim 1 , wherein each of the divided portions has an outer shape of a rectangle.

3. When viewed in a direction perpendicular to the first main surface, the plurality of divisions are A first division portion; a second division portion disposed closer to an outer periphery of the light absorbing film than the first division portion, The optical sensor according to claim 1 , wherein an area of ​​the first divided portion is larger than an area of ​​the second divided portion.

4. The optical sensor according to claim 1 , wherein the plurality of divided portions have the same shape when viewed in a direction perpendicular to the first main surface.

5. The optical sensor according to claim 1 , wherein the groove penetrates the light absorbing film in a thickness direction.

6. The groove is A plurality of first groove-shaped portions extending in a first direction and arranged at intervals in a second direction intersecting the first direction; 3 . The optical sensor according to claim 1 , further comprising: a plurality of second groove-shaped portions extending in the second direction and arranged at intervals in the first direction.

7. When viewed in a direction perpendicular to the first main surface, The outer shape of each of the plurality of divisions is a square, The optical sensor according to claim 2 , wherein the length of one side of the square is not less than 0.1 mm and not more than 0.5 mm.

8. The thickness of the light absorbing film is 3 μm or more, 3. The optical sensor according to claim 1, wherein the light absorbing film has an absorptance of 75% or more for light having a wavelength of 8 μm.

9. The carbon content is 60% by mass or more and 95% by mass or less, The optical sensor according to claim 1 , wherein a content ratio of the resin is 5% by mass or more and 40% by mass or less.

10. 3. The optical sensor according to claim 1, wherein the thermal conductivity of the light absorbing film is 1 W / mK or less.

11. The optical sensor according to claim 1 or 2, wherein the resin includes an epoxy resin.

12. 3. The optical sensor according to claim 1, wherein the light absorbing film has a thickness of 2 μm or more and 7 μm or less.

13. The outer shape of the light absorbing film is rectangular when viewed in a direction perpendicular to the first main surface, 3. The optical sensor according to claim 1, wherein each of the p-type material layers and each of the n-th material layers are arranged such that their longitudinal directions are aligned along an extension direction of one side of the light absorbing film or a direction perpendicular to the extension direction of the one side.

14. 3. The optical sensor of claim 1, wherein the first region and the third region are electrically connected via a first connection portion having electrical conductivity, and the second region and the fourth region are electrically connected via a second connection portion having electrical conductivity.

15. 3. The optical sensor according to claim 1, wherein the first region and the third region of the plurality of p-type material layers overlap when viewed in a direction perpendicular to the first main surface, and the plurality of n-type material layers are connected in ohmic contact, and the second region and the fourth region of the plurality of n-type material layers overlap when viewed in a direction perpendicular to the first main surface, and the second region and the fourth region of the plurality of p-type material layers overlap when viewed in a direction perpendicular to the first main surface, and the plurality of n-type material layers are connected in ohmic contact.

16. 3. The optical sensor of claim 1, wherein at least one of the p-type material layer and the n-type material layer is made of SiGe having at least one of a nanocrystalline structure and an amorphous structure with a grain size of 3 nm or more and 200 nm or less.

17. The optical sensor according to claim 1 , wherein the SiGe is polycrystalline.

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