Light detection device

Abstract

The present disclosure relates to a light detection device for more suitably improving light condensing properties. A light detection device of the present disclosure includes a substrate on which a photoelectric conversion unit is formed for each pixel, a color filter formed for each pixel on a light-receiving surface side of the substrate, and a separation wall that partitions between the color filters for each pixel and in which an air gap is formed. A portion facing the air gap at the upper end of the separation wall on the light-receiving surface side is formed to have an uneven structure in a cross-sectional view. The present disclosure can be applied to, for example, a CMOS image sensor.

Description

Photodetector

[0001] The present disclosure relates to a photodetector, and more particularly to a photodetector that can more suitably improve light-collecting characteristics.

[0002] Patent Document 1 discloses a method for manufacturing an image sensor in which through-holes are formed in a fence material layer and then partially filled to form a fence having an embedded air gap therein in the region between pixels.

[0003] Japanese Patent Application Laid-Open No. 2022-83419

[0004] It is required to improve the light-collecting characteristics by using separation walls that separate the color filters for each pixel.

[0005] The present disclosure has been made in view of such circumstances, and aims to make it possible to more suitably improve the light-collecting characteristics.

[0006] The photodetector disclosed herein comprises a substrate on which a photoelectric conversion unit is formed for each pixel, a color filter formed for each pixel on the light-receiving surface side of the substrate, and a separation wall that separates the color filters for each pixel and has an air gap formed therein, and the portion of the separation wall at the upper end on the light-receiving surface side that faces the air gap is formed so as to have an uneven structure when viewed in cross section.

[0007] In the present disclosure, in a photodetector device comprising a substrate on which a photoelectric conversion unit is formed for each pixel, a color filter formed for each pixel on the light-receiving surface side of the substrate, and a separation wall that separates the color filters for each pixel and has an air gap formed therein, the portion of the separation wall at the upper end on the light-receiving surface side that faces the air gap is formed to have an uneven structure when viewed in cross section.

[0008] 1 is a diagram illustrating an example of the configuration of a CMOS image sensor; FIG. 2 is a cross-sectional view illustrating an example of the configuration of a pixel to which the technology according to the present disclosure is applied; FIG. 3 is a top view illustrating an example of the configuration of a separation wall; FIG. 4 is a top view illustrating an example of the configuration of a separation wall; FIG. 5 is a diagram illustrating an example of the configuration of a separation wall; FIG. 6 is a diagram illustrating a manufacturing process of a pixel; FIG. 7 is a diagram illustrating a manufacturing process of a pixel; FIG. 8 is a diagram illustrating a manufacturing process of a pixel; FIG. 9 is a diagram illustrating a manufacturing process of a pixel; FIG. 10 is a cross-sectional view illustrating another example of the configuration of a pixel; FIG. 11 is a diagram illustrating an example of a concave-convex structure at the upper end of a separation wall; FIG. 12 is a diagram illustrating an example of a concave-convex structure at the upper end of a separation wall; FIG. 13 is a diagram illustrating an example of a concave-convex structure at the upper end of a separation wall; FIG. 14 is a diagram illustrating an example of a concave-convex structure at the upper end of a separation wall; FIG. 15 is a diagram illustrating an example of a cross-sectional shape of an air gap; FIG. 16 is a diagram illustrating an example of a cross-sectional shape of an air gap; FIG. 17 is a diagram illustrating an example of a cross-sectional shape of an air gap;

[0009] Modes for carrying out the present disclosure (hereinafter referred to as embodiments) will be described below in the following order.

[0010] 1. Prior art and its problems 2. Example of CMOS image sensor configuration 3. Pixel configuration 4. Pixel manufacturing process 5. Concave and recessed structure at the top end of the separation wall 6. Cross-sectional shape of the air gap 7. Other

[0011] 1. Prior Art and Problems Thereof Conventionally, in the manufacturing process of an image sensor, the applicant has adopted a method of forming a color filter for each pixel, and then forming a separation wall that separates the color filters and has an air gap therein.

[0012] However, this manufacturing process can affect the light-collection characteristics and reliability due to defects in the color filter and the increased height of the on-chip lens. For example, the color filter can be damaged during processes such as etching and CVD (Chemical Vapor Deposition) for forming the separation wall. Furthermore, an unnecessary inorganic film is formed between the color filter and the on-chip lens material, which increases the lens height and affects the light-collection characteristics.

[0013] Furthermore, color filters contain a large amount of metal components, which can contaminate the equipment that forms the air gap after the color filter is formed, making it impossible to share existing equipment, resulting in large capital investments and line construction man-hours.Furthermore, when changing color filter materials, it is necessary to re-examine the damage to the color filter caused by the separation wall formation process, making it necessary to ensure the reliability of the color filter material.

[0014] In contrast, in the technology according to the present disclosure, by forming a separation wall having an air gap before forming the color filter, defects in the color filter can be avoided and the height of the on-chip lens can be reduced, thereby preventing deterioration in the light-collecting characteristics and reliability due to damage to the color filter during the formation of the separation wall.

[0015] 2. Configuration Example of a CMOS Image Sensor The technology disclosed herein relates to a photodetector device including a substrate on which a photoelectric conversion unit is formed for each pixel, a color filter formed for each pixel on the light-receiving surface side of the substrate, and a separation wall that separates the color filters for each pixel and has an air gap formed therein. The portion of the separation wall at the upper end on the light-receiving surface side that faces the air gap has an uneven structure in cross section.

[0016] FIG. 1 is a diagram showing an example of the configuration of a CMOS (Complementary Metal Oxide Semiconductor) image sensor, which is a photodetector to which the technology of the present disclosure is applied.

[0017] The CMOS image sensor 10 is, for example, a back-illuminated solid-state imaging device, and is configured to have a pixel array section 21 formed on a semiconductor substrate (chip) not shown, and a peripheral circuit section integrated on the same semiconductor substrate as the pixel array section 21.

[0018] The peripheral circuit section includes, for example, a vertical drive section 22 , a column processing section 23 , a horizontal drive section 24 , and a system control section 25 .

[0019] The CMOS image sensor 10 has a signal processing unit 28 and a data storage unit 29. The signal processing unit 28 and the data storage unit 29 may be provided on the semiconductor substrate that constitutes the CMOS image sensor 10, or may be provided on a substrate different from the semiconductor substrate that constitutes the CMOS image sensor 10.

[0020] The pixel array section 21 is configured such that a plurality of unit pixels (hereinafter simply referred to as pixels) each having a photoelectric conversion section that generates and accumulates an electric charge according to the amount of light received are arranged two-dimensionally in the row and column directions, i.e., in a matrix.

[0021] Here, the row direction is the direction in which pixels in a pixel row are arranged (horizontal direction), ie, the lateral direction in the drawing, and the column direction is the direction in which pixels in a pixel column are arranged (vertical direction), ie, the longitudinal direction in the drawing.

[0022] In the pixel array unit 21, pixel drive lines 26 are wired in the row direction for each pixel row, and vertical signal lines 27 are wired in the column direction for each pixel column, for the matrix-like pixel arrangement. The pixel drive lines 26 are signal lines for supplying drive signals (control signals) for driving pixels, such as for driving when reading signals from the pixels. One end of each pixel drive line 26 is connected to an output terminal of the vertical drive unit 22 corresponding to each row.

[0023] For ease of viewing, one pixel drive line 26 is shown for one pixel row here, but in reality, a plurality of pixel drive lines 26 are wired for one pixel row.

[0024] The vertical drive unit 22 is composed of, for example, a shift register, an address decoder, etc., and drives each pixel of the pixel array unit 21 simultaneously for all pixels or in row units, etc. For example, the vertical drive unit 22 is configured to have two scanning systems: a readout scanning system and a sweep scanning system.

[0025] The readout scanning system sequentially selects and scans the unit pixels of the pixel array section 21 row by row in order to read out signals from the unit pixels.

[0026] The sweep scanning system performs sweep scanning at a predetermined timing on the readout row that is to be read out by the readout scanning system. The sweep scanning by the sweep scanning system sweeps out unnecessary charges from the photoelectric conversion units of the unit pixels of the readout row, thereby resetting the photoelectric conversion units.

[0027] The signals output from each unit pixel in the pixel row selected and scanned by the vertical drive section 22 are input to the column processing section 23 via vertical signal lines 27 for each pixel column.

[0028] The column processing unit 23 performs predetermined signal processing on signals supplied from each pixel in a selected row via a vertical signal line 27 for each pixel column in the pixel array unit 21, and temporarily stores the pixel signals after signal processing.

[0029] For example, the column processing unit 23 performs signal processing such as noise removal processing, CDS (Correlated Double Sampling) processing, AD (Analog to Digital) conversion processing, etc. For example, CDS processing removes pixel-specific fixed pattern noise such as reset noise and threshold variations of amplification transistors in pixels.

[0030] The horizontal driving unit 24 is composed of a shift register, an address decoder, etc., and sequentially selects unit circuits corresponding to pixel columns in the column processing unit 23. By selective scanning by the horizontal driving unit 24, pixel signals that have been signal-processed for each unit circuit in the column processing unit 23 are sequentially output to the signal processing unit 28.

[0031] The system control unit 25 includes a timing generator that generates various timing signals, and controls the driving of the vertical driving unit 22, the column processing unit 23, the horizontal driving unit 24, and the like based on the generated timing signals.

[0032] The signal processing unit 28 has at least an arithmetic processing function and performs various signal processing such as arithmetic processing on the pixel signals output from the column processing unit 23. When the signal processing unit 28 performs signal processing, the data storage unit 29 temporarily stores data necessary for the processing.

[0033] 3. Pixel Configuration An example of the configuration of a pixel to which the technology according to the present disclosure is applied will be described with reference to Fig. 2. Fig. 2 is a cross-sectional view showing an example of the configuration of a pixel 30 arranged in a pixel array section 21.

[0034] 2, a photoelectric conversion unit 41 is formed on a substrate 40 made of Si (silicon) for each pixel 30. Although not shown, an isolation unit that isolates the photoelectric conversion unit 41 for each pixel 30, a pixel transistor, a wiring layer, and the like are also formed on the substrate 40.

[0035] An oxide film 50 is formed on the light-receiving surface side (upper side in the figure) of the substrate 40 so as to be shared by a plurality of pixels 30. The oxide film 50 may be formed of any material such as SiO, AlO, or HfO.

[0036] On the oxide film 50, there is provided a color filter 70 formed for each pixel 30 on the light-receiving surface side of the substrate 40, and a film layer 60 that forms a separation wall 60S that separates the color filters 70 for each pixel 30 and has an air gap AG formed therein.

[0037] The color filter 70 may be any one of a red color filter 70R, a green color filter 70G, and a blue color filter 70B, or may be a color filter other than red, green, and blue. In the example of Fig. 2, one pixel 30 has a red color filter 70R, and the other pixel 30 has a green color filter 70G.

[0038] An on-chip lens 80 is formed on the light-receiving surface side of the color filter 70 formed for each pixel 30. The on-chip lens 80 is formed so as to more efficiently allow incident light to be incident on the underlying photoelectric conversion unit 41.

[0039] Here, the separation walls 60S that separate the color filters 70 for each pixel 30 will be described in detail.

[0040] The upper end 60T of the separation wall 60S on the light-receiving surface side has an uneven structure in a cross-sectional view, and the film layer 60 constituting the separation wall 60S may be made of a material such as SiN, SiCN, SiON, or SiO2.

[0041] The separation wall 60S is formed so that the upper end 60T is thicker than the side portions that contact the color filter 70. In other words, the side portions of the separation wall 60S are thinner than the upper end 60T, so the area of ​​the color filter 70 relative to the light-receiving surface can be increased. This can improve the waveguiding characteristics of light incident from the on-chip lens 80 to the photoelectric conversion unit 41.

[0042] 2, the separation wall 60S and the color filter 70 are formed to have the same height, but this is not necessarily limited to this. For example, the separation wall 60S may be formed to be lower than the color filter 70, or the separation wall 60S may be formed to be higher than the color filter 70.

[0043] The film layer 60 constituting the separation wall 60S is composed of a first film 61 having one or more micropores at an upper end 60T and an air gap AG formed therein, and a second film 62 formed to cover the first film 61. The first film 61 and the second film 62 may be formed of the same material among the above-mentioned materials, or may be formed of different materials.

[0044] 3 to 5 are top views showing examples of the configuration of the separation wall 60S.

[0045] 3 to 5, the separation wall 60S is configured in a shape that surrounds the photoelectric conversion unit 41 of each pixel 30 in top view. In addition, in the examples of Figures 3 to 5, micropores 91 that the first film 61 has are shown.

[0046] The micropores 91 may be formed in a honeycomb shape in top view at the upper end 60T of the separation wall 60S (first film 61) as shown in Fig. 3, or may be formed in a row along the separation wall 60S (first film 61) as shown in Fig. 4. Furthermore, the micropores 91 may be formed one at each intersection of a lattice shape surrounding the photoelectric conversion unit 41 of each pixel 30 at the upper end 60T of the separation wall 60S (first film 61).

[0047] According to the above configuration, the separation wall 60S having an air gap therein can more suitably improve the light-collecting characteristics.

[0048] That is, the air gap AG formed in the separation wall 60S has a low refractive index, such as 1.0. When the separation wall 60S includes an air gap AG with a relatively low refractive index, incident light toward the air gap AG is totally reflected and directed toward the center of the photoelectric conversion unit 41. Specifically, the air gap AG can prevent incident light that is incident at an inclined angle into the color filter 70 arranged over one pixel 30 from entering the color filter 70 arranged over an adjacent pixel 30. This makes it possible to prevent crosstalk between multiple pixels 30.

[0049] 4. Pixel Manufacturing Process> The manufacturing process of the pixel 30 described above will be described with reference to FIGS.

[0050] Below, as shown in Figure 6, we will explain the flow of the manufacturing process from the state where an oxide film 50 is formed on the light-receiving surface side (upper side in the figure) of a substrate 40 on which a photoelectric conversion section 41 is formed for each pixel 30, and then an amorphous silicon (a-Si) layer 110 is formed.

[0051] 6, a plurality of micro-hole patterns 121 are formed on the light-receiving surface side of the amorphous silicon (a-Si) layer 110. The diameter of the micro-hole patterns 121 is set to, for example, about 20 to 30 nm.

[0052] 7, photoresist 131 is applied to the light-receiving surface side of a-Si layer 110, and then a photomask 132 is formed in the region that partitions the pixels 30. By undergoing the processes of exposure, development, etching, and resist removal from the state shown in FIG. 7, a silicon wall 110W having a plurality of microhole patterns 121 on its upper surface is formed in the region that partitions the pixels 30 on the light-receiving surface side of substrate 40, as shown in FIG.

[0053] 9, the first film 61 is formed on the silicon wall 110W under conditions that do not clog the micropore pattern 121. At this time, the first film 61 is formed by a film formation method such as CVD or ALD (Atomic Layer Deposition) with reduced coverage characteristics. This allows the first film 61 to be formed by self-alignment so that the micropore pattern 121 of the silicon wall 110W is not clogged and has multiple micropores 91 at the upper end.

[0054] From the state shown in FIG. 9, the silicon wall 110W is removed from inside the first film 61 by etching back through the fine holes 91, thereby forming an air gap AG inside the first film 61 as shown in FIG.

[0055] 11 , a second film 62 is formed on a first film 61 having micropores 91 at its upper end and an air gap AG formed therein under conditions that close the micropores 91, thereby forming a film layer 60. Unlike the first film 61, the second film 62 is formed using a film formation method such as CVD or ALD to enhance its coverage. This results in an air gap AG formed therein, and a separation wall 60S having an uneven structure in cross section at the upper end on the light-receiving surface side, facing the air gap AG. Because the micropores 91 are very fine, the thickness of the second film 62 that closes the micropores 91 can be reduced, resulting in the formation of a separation wall 60S with high light-collection characteristics.

[0056] In the step shown in FIG. 11, the film layer 60 may be removed from the light-receiving surface side (upper side in the drawing) of the oxide film 50 except for the region where the separation wall 60S is formed.

[0057] 12, color filters 70 (70R, 70G) are applied to the areas partitioned by the separation walls 60S, and as shown in Fig. 13, an on-chip lens 80 is formed for each pixel 30. In this manner, the pixels 30 can be formed.

[0058] According to the above process, in the manufacturing process of an image sensor, before forming the color filters for each pixel, it is possible to form separation walls that separate the color filters. This makes it possible to avoid defects in the color filters without damaging the color filters during processes such as etching and CVD for forming the separation walls. Furthermore, it is possible to achieve a low profile for the on-chip lens without forming an unnecessary inorganic film between the color filter and the on-chip lens material. As a result, it is possible to prevent deterioration in light-collection characteristics and reliability due to damage to the color filters during the formation of the separation walls.

[0059] In the above description, an example has been described in which a plurality of micropores 91 are formed in the upper end portion 60T of the separation wall 60S (first film 61) between the pixels 30 in a cross-sectional view.

[0060] However, as shown in FIG. 14, one micropore 91 may be formed in a cross-sectional view at an upper end 60T' of a separation wall 60S (first film 61) between pixels 30.

[0061] 5. Uneven Structure at Upper End of Separation Wall Hereinafter, an example of the uneven structure at the upper end 60T of the separation wall 60S will be described.

[0062] The upper end face (surface) of the separation wall 60S on the light-receiving surface side may be configured to be flat or may be configured to have an uneven shape.

[0063] For example, as shown in FIG. 15, the upper end surface of the upper end portion 60T of the separation wall 60S on the light receiving surface side may be configured in a moth-eye structure.

[0064] As shown in FIG. 16, the upper end surface of the upper end portion 60T of the separation wall 60S on the light-receiving surface side may be configured to include a recessed portion having a curvature.

[0065] Furthermore, as shown in FIG. 17, the upper end surface of the upper end portion 60T of the separation wall 60S on the light receiving surface side may be made up of a concave portion and a convex portion having a curvature.

[0066] The shape of the upper end surface of these separation walls 60S on the light-receiving surface side can be determined by the coating characteristics when forming the second film 62, the spacing and diameter of the micropores 91 to be closed, and the like.

[0067] 9, when the first film 61 is formed on the silicon wall 110W under conditions that prevent the micropore pattern 121 from clogging, it is desirable that the upper end face (surface) of the first film 61 on which the micropores 91 are formed be uniform. That is, it is ideal that the uneven structure at the upper end 60T of the separation wall 60S is configured to have a uniform height in cross-sectional view.

[0068] However, when the first film 61 is formed under conditions that do not cause the micropore pattern 121 to become clogged, a portion of the first film 61 may enter the recesses (holes) of the micropore pattern 121, and the upper surface of the first film 61 on which the micropores 91 are formed may become uneven, as shown in Fig. 18. In this case, the uneven structure at the upper end 60T of the separation wall 60S may be configured to have an uneven height in cross-sectional view.

[0069] <6. Cross-sectional shape of the air gap> The cross-sectional shape of the air gap AG formed inside the separation wall 60S can take various shapes depending on the film formation conditions of the first film 61 and the second film 62 that make up the separation wall 60S (film formation layer 60).

[0070] For example, as shown in FIG. 19, the separation wall 60S may be formed so that the air gap AG has a spindle shape in cross section.

[0071] As shown in FIG. 20, the separation wall 60S may be formed so that the shape of the air gap AG tapers toward the light receiving surface side (upper side in the drawing) in cross section.

[0072] Furthermore, as shown in FIG. 21, the separation wall 60S may be formed so that the shape of the air gap AG is tapered toward the substrate 40 (oxide film 50) in a cross-sectional view.

[0073] Furthermore, as shown in FIG. 22, the separation wall 60S may be formed so that the air gap AG has an inverted spindle shape in cross section.

[0074] 7. Others The embodiments described above can be combined as appropriate.

[0075] Furthermore, the technology disclosed herein can be applied to photodetection devices in general, including not only solid-state imaging devices such as the CMOS image sensors described above, but also distance measurement sensors that measure distance, also known as Time of Flight (ToF) sensors. A distance measurement sensor emits light toward an object, detects the light reflected from the surface of the object, and calculates the distance to the object based on the time of flight between the emission of the light and the reception of the reflected light. The pixel structure of this distance measurement sensor can employ the structure of pixel 30 described above.

[0076] Furthermore, the technology disclosed herein is not limited to image sensors having a pixel array section in which pixels are arranged two-dimensionally, but can also be applied to line sensors in which pixels are arranged one-dimensionally (specifically, arranged in one or several rows).

[0077] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0078] Furthermore, the embodiments to which the technology according to the present disclosure is applied are not limited to the above-described embodiments, and various modifications are possible within the scope that does not deviate from the gist of the technology according to the present disclosure.

[0079] Furthermore, the present disclosure may have the following configurations. (1) A photodetector comprising: a substrate on which a photoelectric conversion unit is formed for each pixel; a color filter formed for each pixel on the light-receiving surface side of the substrate; and a separation wall that partitions the color filters for each pixel and has an air gap formed therein, wherein a portion of the separation wall at its upper end on the light-receiving surface side that faces the air gap is formed to have an uneven structure in cross-section. (2) The photodetector described in (1), in which the upper end surface of the separation wall on the light-receiving surface side is formed in a moth-eye structure. (3) The photodetector described in (1), in which the upper end surface of the separation wall on the light-receiving surface side is configured to include a concave portion having a curvature. (4) The photodetector described in (1), in which the upper end surface of the separation wall on the light-receiving surface side is composed of concave portions and convex portions having a curvature. (5) The photodetector described in any of (1) to (4), in which the uneven structure is configured to have a uniform height in cross-section. (6) The photodetector according to any one of (1) to (4), wherein the uneven structure has a non-uniform height in cross section. (7) The photodetector according to any one of (1) to (6), wherein the separation wall is formed so that the upper end is thicker than the side portions that contact the color filter. (8) The photodetector according to any one of (1) to (7), wherein the separation wall is formed so that the air gap has a spindle shape in cross section. (9) The photodetector according to any one of (1) to (7), wherein the separation wall is formed so that the air gap has a tapered shape toward the light-receiving surface in cross section. (10) The photodetector according to any one of (1) to (7), wherein the separation wall is formed so that the air gap has a tapered shape toward the substrate in cross section. (11) The photodetector according to any one of (1) to (7), wherein the separation wall is formed so that the air gap has an inverted spindle shape in cross section. (12) The photodetector according to any one of (1) to (11), wherein the separation wall is composed of a first film having one or more micropores at the upper end and the air gap formed therein, and a second film formed to cover the first film. (13) The photodetector according to (12), wherein the first film and the second film are formed of the same material.(14) The photodetector according to (12), wherein the first film and the second film are formed of different materials. (15) A method for manufacturing a photodetector, comprising: forming a silicon wall having one or more micropores on an upper end surface in a region separating pixels on a light-receiving surface side of a substrate on which a photoelectric conversion unit is formed for each pixel; depositing a first film on the silicon wall under conditions that the micropore is not blocked; removing the silicon wall from inside the first film by etching through the micropores; depositing a second film on the first film having the micropores on an upper end and an air gap formed therein under conditions that the micropore is blocked; and applying a color filter to each of the pixels.

[0080] 10 CMOS image sensor, 21 pixel array section, 30 pixel, 40 pixel substrate, 41 photoelectric conversion section, 50 oxide film, 60 film deposition layer, 60S separation wall, 60T upper end portion, 61 first film, 62 second film, 70 color filter, 80 on-chip lens

Claims

1. A photodetector comprising: a substrate on which a photoelectric conversion unit is formed for each pixel; a color filter formed for each pixel on the light-receiving surface side of said substrate; and a separation wall that separates the color filters for each pixel and has an air gap formed therein, wherein the portion of the separation wall at the upper end on the light-receiving surface side that faces the air gap is formed so as to have an uneven structure in cross section.

2. The photodetector according to claim 1, wherein the upper end surface of the separation wall on the light receiving surface side is configured in a moth-eye structure.

3. The photodetector according to claim 1, wherein the upper end surface of the separation wall on the light receiving surface side is configured to include a recess having a curvature.

4. The photodetector according to claim 1, wherein the upper end surface of said separation wall on the light receiving surface side is composed of a concave portion and a convex portion having a curvature.

5. The photodetector according to claim 1, wherein the uneven structure has a uniform height in cross section.

6. The photodetector according to claim 1, wherein the uneven structure has a non-uniform height in cross section.

7. The photodetector according to claim 1, wherein the separation wall is formed so that the upper end is thicker than the side portions that contact the color filters.

8. The photodetector according to claim 1, wherein the separation wall is formed so that the air gap has a spindle shape in cross section.

9. The photodetector according to claim 1, wherein the separation wall is formed so that the shape of the air gap tapers toward the light-receiving surface side in a cross-sectional view.

10. The photodetector according to claim 1, wherein the separation wall is formed so that the shape of the air gap tapers toward the substrate in a cross-sectional view.

11. The photodetector according to claim 1, wherein the separation wall is formed so that the air gap has an inverted spindle shape in cross section.

12. The photodetector device according to claim 1, wherein the separation wall is composed of a first film having one or more microscopic holes at the upper end and having the air gap formed therein, and a second film formed to cover the first film.

13. The photodetector device according to claim 12, wherein the first film and the second film are formed of the same material.

14. The photodetector device according to claim 12, wherein the first film and the second film are formed of different materials.

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