Photodetector element

Abstract

A photodetector element comprising a substrate on which a plurality of light receiving units are arrayed in units of pixels, and a filter formed on the substrate across a plurality of pixels adjacent to each other, the filter cutting out visible light and transmitting infrared light.

Description

[Technical Field]

[0001] The present technology relates to a photodetector element, and more particularly to the technical field of a photodetector element that detects infrared light. [Background technology]

[0002] As a filter that cuts visible light and transmits infrared light, one has been proposed in which a dielectric multilayer film that transmits infrared light of a predetermined wavelength is formed on a glass substrate located away from the sensor (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-76990 Summary of the Invention [Problem to be solved by the invention]

[0004] The filter described in Patent Document 1 is made up of a stack of multiple inorganic films with different refractive indices, so the wavelength of the transmitted light changes depending on the angle of incidence of the light. Therefore, in a photodetector using the filter described in Patent Document 1, there is a risk that the detection accuracy of infrared light will decrease.

[0005] The present technology has been made in view of the above circumstances, and aims to improve the detection accuracy of infrared light. [Means for solving the problem]

[0006] The photodetector element according to the present technology includes a substrate on which a plurality of light receiving units are arranged in pixel units, and a filter formed on the substrate across a plurality of adjacent pixels, which filters out visible light and transmits infrared light. This makes it possible for the light receiving section of each pixel to receive infrared light with reduced wavelength variation due to differences in the angle of incidence of the light. The phrase "formed on a substrate" includes a case where the element is formed directly on the substrate and a case where the element is formed on the substrate via another member.

[0007] In the photodetector element according to the present technology described above, it is considered that the filter is formed over the entire surface of an effective pixel region in which effective pixels that detect the infrared light are arranged. This makes it possible for the light receiving section of at least one effective pixel arranged in the effective pixel area to receive infrared light with reduced wavelength change due to differences in the angle of incidence of the light.

[0008] In the photodetector element according to the present technology described above, it is considered that the filter is formed over the entire surface of a dummy pixel region in which dummy pixels provided outside the effective pixel region are arranged. This cuts off visible light in the dummy pixel region as well, making it possible to reduce color mixing from the dummy pixels and visible light reflected in the dummy pixel region.

[0009] In the photodetector according to the present technology described above, it is considered that the filter is formed over the entire surface of a light-shielding pixel region in which light-shielding pixels provided outside the dummy pixel region are arranged. This allows visible light to be blocked even in the light-shielding pixel region, making it possible to reduce the visible light reflected in the light-shielding pixel region.

[0010] In the photodetector element according to the present technology described above, it is considered that the filter is formed on the entire surface of the substrate. This makes it possible to reduce visible light reflected on the substrate.

[0011] In the photodetector according to the present technology described above, the filter may be made of an organic resin composition in which a coloring material that cuts visible light is dispersed in an organic resin. This allows infrared light of any wavelength to pass through.

[0012] In the photodetector element according to the present technology described above, it is conceivable that the filter is made of the same material as a microlens that focuses light onto the light receiving portion, and is formed integrally with the microlens. This makes it possible to form the filter and the microlens at the same time.

[0013] The above-described photodetector according to the present technology may include a microlens formed on the substrate that focuses light onto the light receiving portion, and the filter may be formed on the microlens formed on the substrate. This makes it possible to focus only infrared light with the microlens.

[0014] In the photodetector element according to the present technology described above, it is considered that the filter is formed in an effective pixel area excluding some effective pixels. This allows some of the effective pixels to receive visible light.

[0015] The above-described photodetector according to the present technology may include a light-shielding film formed outside an effective pixel area and cutting at least infrared light, and the filter may be formed closer to the substrate than the light-shielding film. This also makes it possible to reduce reflection of infrared light outside the effective pixel area.

[0016] The photodetector element according to the present technology described above may include a light-shielding film formed outside the effective pixel area and configured to cut at least infrared light, and the filter may be formed at a position farther away from the substrate than the light-shielding film. This also makes it possible to reduce reflection of infrared light outside the effective pixel area.

[0017] In the photodetector according to the present technology described above, the light-shielding film may cut visible light and infrared light. This also makes it possible to further reduce the reflection of visible light.

[0018] In the photodetector according to the present technology described above, the light-shielding film may be made of an organic resin composition in which a coloring material that blocks visible light is dispersed in an organic resin. This makes it possible to reduce the influence of the incident angle of light. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a block diagram illustrating a configuration example of a photodetector according to the present technology. [Figure 2] FIG. 2 is a cross-sectional view for explaining a configuration example of a pixel array section. [Figure 3] FIG. 2 is a diagram for explaining a filter arrangement in a pixel array section. [Figure 4] FIG. 10 is a diagram illustrating an example of the spectral characteristics of an infrared light pass filter. [Figure 5] 10 is a flowchart showing the flow of pixel formation processing. [Figure 6] FIG. 10 is a diagram for explaining the flow of pixel formation processing. [Figure 7] FIG. 10 is a diagram showing a first example of a forming range of an infrared light pass filter. [Figure 8] FIG. 10 is a diagram showing a second example of the formation range of the infrared light pass filter. [Figure 9] FIG. 10 is a diagram showing a third example of the formation range of the infrared light pass filter. [Figure 10] FIG. 10 is a diagram showing a fourth example of the formation range of the infrared light pass filter. [Figure 11] FIG. 10 is a diagram showing a fifth example of the formation range of the infrared light pass filter. [Figure 12] FIG. 10 is a diagram showing a sixth example of the formation range of the infrared light pass filter. [Figure 13] FIG. 10 is a diagram showing a second example of a separation wall. [Figure 14] FIG. 10 is a diagram showing a third example of a separation wall; [Figure 15] FIG. 10 is a diagram showing a fourth example of a separation wall; [Figure 16] FIG. 10 is a diagram showing a fifth example of a separation wall; [Figure 17] FIG. 10 is a diagram showing a sixth example of a separation wall; [Figure 18] FIG. 7 is a diagram showing a seventh example of a separation wall. [Figure 19] FIG. 10 is a diagram showing an eighth example of a separation wall; [Figure 20] FIG. 10 is a diagram illustrating a second example of a semiconductor substrate. [Figure 21] FIG. 10 is a diagram illustrating a third example of a semiconductor substrate. [Figure 22] 1 is a block diagram illustrating an application example of a photodetector element according to the present technology. [Figure 23] 10A and 10B are diagrams illustrating modified examples of the formation range of the infrared light pass filter. [Figure 24] 10A and 10B are diagrams illustrating modified examples of the infrared light pass filter. [Figure 25] FIG. 10 is a diagram illustrating a modified example of the pixel array section. [Figure 26] FIG. 10 is a diagram illustrating a modified example of the pixel array section. [Figure 27] FIG. 10 is a diagram illustrating a modified example of the pixel array section. [Figure 28] FIG. 10 is a diagram illustrating a modified example of the pixel array section. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present technology will be described in the following order with reference to the accompanying drawings. <1. Structure of the photodetector element> 2. Pixel array configuration 3. Pixel formation process <4. Infrared light pass filter formation range> <5. Example of separation wall configuration> <6. Example of semiconductor substrate configuration> <7. Application examples of photodetector elements> <8. Variations> <9. Summary of embodiments> <10. This Technology>

[0021] <1. Structure of the photodetector element> 1 is a block diagram illustrating a configuration example of a photodetector 1 according to the present technology. As shown in Fig. 1, the photodetector 1 includes a pixel array unit 11, a vertical driver 12, a system controller 13, a column processor 14, a horizontal driver 15, and a signal processor 16.

[0022] A plurality of pixels Px are arranged two-dimensionally in a matrix in the row and column directions in the pixel array section 11. Each pixel Px has a photodiode PD as a light receiving section.

[0023] Here, the row direction refers to the horizontal arrangement direction of the pixels Px, and the column direction refers to the vertical arrangement direction of the pixels Px. In the drawing, the row direction is the horizontal direction and the column direction is the vertical direction. In the following, the row direction may be referred to as the "X direction," the column direction as the "Y direction," and the direction perpendicular to the XY plane (i.e., the thickness direction of the photodetector element 1) as the "Z direction."

[0024] The pixel array section 11 is provided with an effective pixel region 21, a dummy pixel region 22, and a light-shielded pixel region 23. The effective pixel region 21 is provided in the center of the pixel array section 11, and has a majority of pixels Px arranged therein. The dummy pixel region 22 is provided on the periphery of the effective pixel region 21, and has pixels Px arranged so as to surround the effective pixel region 21. The light-shielded pixel region 23 is provided on the periphery of the dummy pixel region 22, and has pixels Px arranged so as to surround the dummy pixel region 22. The dummy pixel region 22 and the light-shielded pixel region 23 may be provided adjacent to only one side or multiple sides of the periphery of the effective pixel region 21.

[0025] In the following, the pixels Px arranged in the effective pixel region 21 may be referred to as effective pixels 24, the pixels Px arranged in the dummy pixel region 22 as dummy pixels 25, and the pixels Px arranged in the light-shielded pixel region 23 as light-shielded pixels (optical black pixels) 26. Furthermore, when the effective pixels 24, dummy pixels 25, and light-shielded pixels 26 are described without distinction, they will all be referred to as pixels Px.

[0026] The effective pixels 24 receive incident light (infrared light). The dummy pixels 25 are provided to stabilize the pixel characteristics of the effective pixels 24 and the light-shielded pixels 26, and are capable of receiving incident light (infrared light). The light-shielded pixels 26 are pixels for dark current correction, and are light-shielded so as not to receive light, as will be described in detail later.

[0027] In the pixel array unit 11, row drive lines 17 are wired in the row direction for each pixel row in the matrix-like pixel arrangement, and vertical signal lines 18 are wired in the column direction for each pixel column. For example, the row drive lines 17 transmit drive signals for driving the pixels Px when reading out signals. One end of the row drive line 17 is connected to an output terminal of the vertical drive unit 12 corresponding to each row.

[0028] The system control unit 13 is composed of a timing generator that generates various timing signals, and controls the driving of the vertical driving unit 12, column processing unit 14, horizontal driving unit 15, etc. based on the various timing signals generated by the timing generator.

[0029] The vertical drive unit 12 is configured with a shift register, an address decoder, etc., and drives the pixels Px of the pixel array unit 11 all at once or in row units, etc. In other words, the vertical drive unit 12, together with the system control unit 13 that controls the vertical drive unit 12, constitutes a drive control unit that controls the operation of each pixel Px of the pixel array unit 11.

[0030] A detection signal output (read) from each pixel Px in a pixel row in response to drive control by the vertical drive unit 12, specifically a signal corresponding to the signal charge accumulated in a floating diffusion provided for each pixel Px, is input to a column processing unit 14 through a corresponding vertical signal line 18. The column processing unit 14 performs predetermined signal processing on the detection signal read from each pixel Px through the vertical signal line 18, and temporarily stores the processed detection signal. Specifically, the column processing unit 14 performs signal processing such as noise removal and A / D (Analog to Digital) conversion.

[0031] The horizontal driving unit 15 is configured with a shift register, an address decoder, etc., and sequentially selects unit circuits corresponding to pixel columns in the column processing unit 14. Through selective scanning by this horizontal driving unit 15, detection signals that have been signal-processed for each unit circuit in the column processing unit 14 are sequentially output.

[0032] The signal processing unit 16 has at least an arithmetic processing function, and performs various signal processing on the detection signals output from the column processing unit 14 and outputs the results. For example, the signal processing unit 16 may perform only buffering in some cases, or may perform black level adjustment, column variation correction, various digital signal processing, etc.

[0033] 2. Pixel array configuration Fig. 2 is a cross-sectional view for explaining an example of the configuration of the pixel array section 11. Fig. 3 is a diagram for explaining the filter arrangement in the pixel array section 11. As shown in Fig. 2, the pixel array section 11 receives incident light from one surface Sa side (upper side in the figure) of a semiconductor substrate 31 on which photodiodes PD are formed in pixel units.

[0034] The semiconductor substrate 31 is made of, for example, silicon (Si) and is formed to have a thickness of, for example, about 1 μm to 6 μm. In the semiconductor substrate 31, for example, an N-type (second conductivity type) semiconductor region 31b is formed in a P-type (first conductivity type) semiconductor region 31a in a pixel unit, thereby forming a photodiode PD in a pixel unit. The P-type semiconductor regions 31a provided on both sides of the semiconductor substrate 31 also serve as hole charge accumulation regions for suppressing dark current.

[0035] One surface Sa of the semiconductor substrate 31 serves as a light incident surface onto which light is incident. An infrared light pass filter 32 is formed on the one surface Sa of the semiconductor substrate 31. The infrared light pass filter 32 is formed across a plurality of adjacent pixels, and as an example, is formed across all pixels Px as indicated by "IR" in FIG. 3.

[0036] The infrared light pass filter 32 is a filter that cuts (absorbs) visible light and transmits infrared light. Specifically, the infrared light pass filter 32 is an organic resin composition containing a coloring material that cuts visible light dispersed in an organic resin. The organic resin composition is preferably a photocurable composition containing at least a photopolymerization initiator or a thermosetting composition containing at least a thermosetting resin.

[0037] The coloring material is preferably one having a transmission spectral characteristic of blocking visible light of a predetermined wavelength and transmitting infrared light of a predetermined wavelength. The coloring material is, for example, a mixture of multiple organic pigments that have high light blocking properties in the red, green, and blue visible light ranges and low light blocking properties in the infrared light range. Organic pigments include, for example, CI Pigment Yellow 11, 24, 31, 53, 83, 93, 99, 108, 109, 110, 138, 139, 147, 150, 151, 154, 155, 167, 180, 185, and 199; CIPigment Orange 36,38,43,71; CIPigment Red 81,105,122,149,150,155,171,175,176,177,209,220,224,242,254,255,264,270; CIPigment Violet 19,23,32,39; CIPigment Blue 1,2,15,15:1,15:3,15:6,16,22,60,66; CIPigment Green 7,36,37; CIPigment Brown 25,28; CIPigment Black 1,7; Examples include:

[0038] In addition to the organic pigment, a near-infrared absorbing dye can also be added to the organic resin composition. Examples of near-infrared absorbing dyes include pyrrolopyrrole dyes, copper compounds, cyanine dyes, phthalocyanine compounds, immonium compounds, thiol complex compounds, transition metal oxide compounds, squarylium dyes, naphthalocyanine dyes, quattarylene dyes, dithiol metal complex dyes, and croconium compounds.

[0039] Fig. 4 is a diagram showing an example of the spectral characteristics of the infrared light pass filter 32. The infrared light pass filter 32 can have spectral characteristics such as those shown in Fig. 4 by containing the above-mentioned organic pigment, or the organic pigment and near-infrared absorbing dye dispersed in an organic resin.

[0040] As shown by the dashed line in FIG. 4, the infrared light pass filter 32 can be configured to have a transmittance of 10% or less in the wavelength range of approximately 650 nm or less, and a transmittance of 90% or more in the wavelength range of higher than approximately 650 nm.

[0041] Furthermore, as shown by the solid line in FIG. 4, the infrared light pass filter 32 can be configured to have a transmittance of 10% or less in the wavelength range of approximately 800 nm or less, and a transmittance of 90% or more in the wavelength range of more than approximately 800 nm.

[0042] Furthermore, as shown by the dashed line in FIG. 4, the infrared light pass filter 32 can be configured to have a transmittance of 10% or less in the wavelength range of approximately 900 nm or less, and a transmittance of 90% or more in the wavelength range of more than approximately 900 nm.

[0043] 2, separation walls 33 for preventing incident light from entering adjacent pixels (color mixing) are formed on the semiconductor substrate 31 and within the infrared light pass filter 32. These separation walls 33 are formed in a lattice pattern so as to open the photodiode PD of each pixel Px. It is desirable that the height of the separation walls 33 in the Z direction be at least 100 nm or more and be equal to or less than the height (thickness) of the infrared light pass filter 32.

[0044] The material of the separation wall 33 may be any material that blocks light, such as a metal material (metal film) such as tungsten (W), aluminum (Al), or copper (Cu). The separation wall 33 can prevent light that should be incident only on one pixel Px from leaking into the other pixel Px between adjacent pixels Px.

[0045] A microlens 34 is formed for each pixel Px on the infrared light pass filter 32. The microlens 34 is made of a resin material (lens material) such as a styrene resin, an acrylic resin, a styrene-acrylic copolymer resin, or a siloxane resin. The light collected by the microlens 34 is efficiently incident on the photodiode PD.

[0046] 3. Pixel formation process Fig. 5 is a flowchart showing the flow of pixel formation processing. Fig. 6 is a diagram for explaining the flow of pixel formation processing. Next, the flow of processing up to the formation of pixels Px in the pixel array section 11 will be explained. Note that, hereinafter, processing after the photodiode PD is formed on the semiconductor substrate 31 will be explained.

[0047] 5, a metal film that will be the material of the separation wall 33 is formed on one surface Sa of the semiconductor substrate 31. In step S2, a photoresist is applied to the area where the separation wall 33 is to be formed, and the photoresist is exposed and developed by photolithography, and then dry etched to form the separation wall 33 as shown in the upper part of FIG.

[0048] In step S3, an organic resin composition that will be the material for the infrared light pass filter 32 is spin-coated onto one surface Sa of the semiconductor substrate 31. Then, because the organic resin composition has photolithography properties, the organic resin composition is directly exposed and developed to form the infrared light pass filter 32 as shown in the center of FIG.

[0049] In step S4, a lens material that will become the microlens 34 is applied onto the infrared light pass filter 32. Then, the lens material is subjected to a positive resist patterning process, a lens shape formation process by thermal reflow, and a microlens shape transfer process by dry etching, in that order, to form the microlens 34 as shown in the lower part of FIG.

[0050] <4. Formation range of the infrared light pass filter 32> Next, the formation range of the infrared light pass filter 32 will be described. Fig. 7 is a diagram showing a first example of the formation range of the infrared light pass filter 32. Fig. 8 is a diagram showing a second example of the formation range of the infrared light pass filter 32. Fig. 9 is a diagram showing a third example of the formation range of the infrared light pass filter 32. Fig. 10 is a diagram showing a fourth example of the formation range of the infrared light pass filter 32. Fig. 11 is a diagram showing a fifth example of the formation range of the infrared light pass filter 32. Fig. 12 is a diagram showing a sixth example of the formation range of the infrared light pass filter 32. Figs. 7 to 12 show cross-sectional views of the pixel array section 11.

[0051] 7 to 12, an effective pixel region 21, a dummy pixel region 22, and a light-shielded pixel region 23 are arranged in this order from the right side to the left side in the pixel array section 11. Note that a portion of effective pixels 24 is shown in the effective pixel region 21. In addition, in FIGS. 7 to 12, the right direction is the direction toward the center of the effective pixel region 21, and the left direction is the direction toward the outside (edge) of the semiconductor substrate 31.

[0052] A metal film 41 is formed on the light-shielded pixel region 23 on one surface Sa of the semiconductor substrate 31, and the light-shielded pixels 26 are shielded from light by the metal film 41. In addition, a connection hole 42 is provided at the left end of the figure, into which a conductor connected to an electrode pad formed on the semiconductor substrate 31 is embedded.

[0053] 7, in a first example of the formation range of the infrared light pass filter 32, the infrared light pass filter 32 is formed over the entire surface of the effective pixel region 21, and is not formed on the dummy pixel region 22 or the light-shielding pixel region 23. This makes it possible to cut out visible light from the light that directly irradiates at least the effective pixels 24, and to transmit only infrared light.

[0054] 8, in a second example of the formation range of the infrared light pass filter 32, the infrared light pass filter 32 is formed over the entire surface of the effective pixel region 21 and the dummy pixel region 22, but is not formed on the light-shielded pixel region 23. This makes it possible to cut visible light out of the light directly incident on the effective pixel 24 and transmit only infrared light, and also cut visible light in the dummy pixel region 22 and transmit only infrared light. That is, it is possible to suppress the effects of flare caused by visible light reflected in the dummy pixel region 22. Furthermore, by using the infrared light pass filter 32 to cut visible light incident toward the effective pixel 24 from the adjacent dummy pixel 25, it is possible to reduce color mixing.

[0055] As shown in FIG. 9 , in a third example of the formation range of the infrared light pass filter 32, the infrared light pass filter 32 is formed over the entire surfaces of the effective pixel region 21, the dummy pixel region 22, and the light-shielding pixel region 23, but is not formed to the outside (edge) of the semiconductor substrate 31. In the light-shielding pixel region 23, the infrared light pass filter 32 is formed on a metal film 41. This allows visible light to be cut out of the light directly incident on the effective pixel 24 and only infrared light to be transmitted, and also allows the infrared light pass filter 32 to cut visible light in the dummy pixel region 22 and the light-shielding pixel region 23 and only infrared light to be transmitted. That is, it is possible to further suppress the effects of flare caused by visible light reflection in the dummy pixel region 22 and the light-shielding pixel region 23. Furthermore, it is possible to reduce color mixing by cutting out visible light incident from the adjacent dummy pixel 25 toward the effective pixel 24.

[0056] As shown in FIG. 10 , in a fourth example of the formation range of the infrared light pass filter 32, the infrared light pass filter 32 is formed over the entire surface of the semiconductor substrate 31, including the effective pixel region 21, the dummy pixel region 22, and the light-shielding pixel region 23. This cuts out visible light from the light directly incident on the effective pixels 24 and transmits only infrared light, and also cuts out visible light from regions other than the effective pixels 24 on the semiconductor substrate 31 and transmits only infrared light. That is, it is possible to further suppress the effects of flare caused by visible light reflected in regions other than the effective pixels 24 on the semiconductor substrate 31. In addition, it is possible to reduce color mixing by cutting out visible light incident from the adjacent dummy pixels 25 toward the effective pixels 24. Furthermore, it is advantageous that the infrared light pass filter 32 is disposed over the entire surface as a measure against collet scratches during assembly.

[0057] In a fifth example of the formation range of the infrared light pass filter 32 shown in Fig. 11 and a sixth example of the formation range of the infrared light pass filter 32 shown in Fig. 12, the infrared light pass filter 32 is formed over the entire surface of the semiconductor substrate 31, similar to the fourth example of the formation range of the infrared light pass filter 32 shown in Fig. 10. On the other hand, in the fifth and sixth examples of the formation range of the infrared light pass filter 32, a light-shielding organic film 43 is formed on the semiconductor substrate 31, unlike the fourth example.

[0058] 11 , in the fifth example of the formation range of the infrared light pass filter 32, the light-shielding organic film 43 is formed on the infrared light pass filter 32. That is, the infrared light pass filter 32 is formed closer to the semiconductor substrate 31 than the light-shielding organic film 43. The light-shielding organic film 43 is formed over the entire light-shielding pixel region 23 and extends outside the light-shielding pixel region 23.

[0059] The light-shielding organic film 43 is made of an organic resin composition containing a coloring material that blocks at least infrared light dispersed in an organic resin. The light-shielding organic film 43 may also contain a coloring material that blocks visible light. The organic resin composition is preferably a photocurable composition that contains at least a photopolymerization initiator or a thermosetting composition that contains at least a thermosetting resin.

[0060] The coloring material may be a mixture of an organic pigment that blocks visible light and an organic dye that blocks infrared light, or may contain an organic compound such as carbon black or a metal compound such as titanium black that blocks visible light and infrared light.

[0061] Thus, in the fifth example of the formation range of the infrared light pass filter 32, by combining the infrared light pass filter 32 with the light-shielding organic film 43 on the light-shielding pixel region 23 and outside the light-shielding pixel region 23, it is possible to cut not only visible light but also infrared light.

[0062] 12, in a sixth example of the formation range of the infrared light pass filter 32, the light-shielding organic film 43 is formed between the metal film 41 and the infrared light pass filter 32. That is, the infrared light pass filter 32 is formed at a position farther away from the semiconductor substrate 31 than the light-shielding organic film 43. Specifically, in the sixth example, after the metal film 41 is formed on the semiconductor substrate 31, the light-shielding organic film 43 is formed thereon, and then the infrared light pass filter 32 is further formed.

[0063] In the sixth example of the formation range of the infrared light pass filter 32, as in the fifth example of the formation range of the infrared light pass filter 32, by combining the infrared light pass filter 32 with the light-shielding organic film 43, it is possible to cut not only visible light but also infrared light above the light-shielding pixel region 23 and outside the light-shielding pixel region 23.

[0064] <5. Example of separation wall configuration> Next, the configuration of the separation wall will be described. Fig. 2 shows a first example of the separation wall. Fig. 13 is a diagram showing a second example of the separation wall. Fig. 14 is a diagram showing a third example of the separation wall. Fig. 15 is a diagram showing a fourth example of the separation wall. Fig. 16 is a diagram showing a fifth example of the separation wall. Fig. 17 is a diagram showing a sixth example of the separation wall. Fig. 18 is a diagram showing a seventh example of the separation wall. Fig. 19 is a diagram showing an eighth example of the separation wall.

[0065] 2, the separation wall 33, which is a first example of the separation wall, is formed of a metal film made of W, Al, or the like, and is shorter in height than the infrared light pass filter 32. However, the material and height (thickness) of the separation wall are not limited to this, and the material and height may be, for example, as shown in FIGS.

[0066] 13, a separation wall 51, which is a second example of the separation wall, is formed of a metal film made of W, Al, or the like, and has the same height as the infrared light pass filter 32. Therefore, as can be seen from the first and second examples, it is preferable that the separation wall is formed of a metal film made of W, Al, or the like, and that its height is equal to or less than the height of the infrared light pass filter 32.

[0067] 14, a third example of the separation wall, a separation wall 52, is formed by laminating an inorganic film 52b made of SiO2, SiN, etc. on a metal film 52a made of W, Al, etc. In this case, the total height of the metal film 52a and the inorganic film 52b is preferably equal to or less than the height of the infrared light pass filter 32.

[0068] 15, a separation wall 53, which is a fourth example of the separation wall, is formed of an inorganic film made of SiO2, SiN, etc. In this case, the height of the separation wall 53 is preferably equal to or less than the height of the infrared light pass filter 32.

[0069] 16, a separation wall 54, which is a fifth example of the separation wall, is formed by laminating an organic resin 54b having a predetermined refractive index on a metal film 54a made of W, Al, or the like. In this case, the total height of the metal film 54a and the organic resin 54b is preferably equal to or less than the height of the infrared light pass filter 32. The refractive index of the organic resin 54b is preferably 1.6 or less.

[0070] 17, a separation wall 55, which is a sixth example of the separation wall, is formed of an organic resin having a predetermined refractive index. In this case, the height of the separation wall 55 is preferably equal to or less than the height of the infrared light pass filter 32. The refractive index of the separation wall 55 (organic resin) is preferably 1.6 or less.

[0071] Furthermore, in addition to the configurations of the first to sixth examples, the separation wall may be formed together with a PD separation wall that separates the photodiode PD of each pixel Px for each pixel, as shown in the seventh and eighth examples.

[0072] 18, a seventh example of a separation wall 61 is formed by an intra-filter separation wall 61a formed in the infrared light pass filter 32 and a PD separation wall 61b of a DTI structure having a predetermined depth from one surface Sa of the semiconductor substrate 31. The intra-filter separation wall 61a is formed by a metal film made of W, Al, or the like, an inorganic film made of SiO, SiN, or the like, an organic resin having a predetermined refractive index, or the like. The PD separation wall 61b is formed by embedding an oxide film in the semiconductor substrate 31.

[0073] 19, a separation wall 62, which is an eighth example of the separation wall, is formed by an intra-filter separation wall 62a formed in the infrared light pass filter 32 and a PD separation wall 62b of a DTI structure having a predetermined depth from one surface Sa of the semiconductor substrate 31. The intra-filter separation wall 62a and the PD separation wall 62b are integrally formed from a metal material such as W or Al.

[0074] <6. Example of semiconductor substrate configuration> Next, an example of the configuration of the semiconductor substrate 31 will be described. Fig. 2 shows a first example of the semiconductor substrate 31. Fig. 20 is a diagram showing a second example of the semiconductor substrate 31. Fig. 21 is a diagram showing a third example of the semiconductor substrate 31.

[0075] 2, in the first example of the semiconductor substrate 31, an N-type (second conductivity type) semiconductor region 31b is formed in a pixel unit in a P-type (first conductivity type) semiconductor region 31a, thereby forming a photodiode PD in a pixel unit. However, the semiconductor substrate 31 may have a configuration such as those shown in the second and third examples, as long as it is configured to be able to detect light (infrared light).

[0076] 20, in the second example of the semiconductor substrate 31, in order to improve the particle efficiency (Qe) due to scattering in the photodiode PD, the interface of the semiconductor region 31a may have a structure in which pyramidal structures, which are quadrangular pyramidal concave structures, are periodically arranged. An oxide film is formed on the interface of the semiconductor region 31a.

[0077] 21, in a third example of the semiconductor substrate 31, a structure may be adopted in which trenches of a predetermined depth are periodically formed on the interface of the semiconductor region 31a in order to improve the particle efficiency (Qe) due to scattering in the photodiode PD in the semiconductor substrate 31. An oxide film is formed on the interface of the semiconductor region 31a.

[0078] In addition, the light detection element 1 may be a front-side illumination type in which the photodiode PD receives light from the front side of the semiconductor substrate 31, or may be a front-side illumination type in which the photodiode PD receives light from the back side of the semiconductor substrate 31.

[0079] In addition, the photodetector element 1 may be a stacked type in which the effective pixel region 21, the dummy pixel region 22, and the light-shielding pixel region 23 are stacked on part or all of the vertical drive unit 12, the system control unit 13, the column processing unit 14, the horizontal drive unit 15, and the signal processing unit 16.

[0080] The photodetector element 1 may also be a two-pixel shared type in which one floating diffusion is shared by two photodiodes PD, or a four-pixel shared type in which one floating diffusion is shared by four photodiodes PD.

[0081] <7. Application examples of photodetector elements> 22 is a block diagram illustrating an application example of the photodetector 1 according to the present technology. As shown in Fig. 22, a photodetector device 70 as an application example of the photodetector 1 includes, for example, the photodetector 1, a light emitting unit 71, a control unit 72, a signal processing unit 73, and a memory 74.

[0082] The light emitting unit 71 has one or more light emitting elements as a light source, and emits irradiation light Li to the object Ob. Note that the light detecting device 70 does not necessarily have to be provided with the light emitting unit 71. The control unit 72 appropriately controls the photodetector element 1 and the light emitter 71 to cause the photodetector element 1 to receive infrared light and cause the light emitter 71 to emit irradiation light Li.

[0083] The signal processing unit 73 performs predetermined signal processing on the detection signal obtained by the photodetector element 1 and outputs the processed signal to the memory 74 . The memory 74 is a storage device such as a flash memory, a solid state drive (SSD), or a hard disk drive (HDD), and stores information (data) processed by the signal processing unit 73.

[0084] Here, the photodetector 70 may be any device equipped with a photodetector element 1 that receives infrared light and outputs a detection signal, such as an infrared light imaging device that captures images based on infrared light, or a distance measuring device that measures distance using a ToF (Time of Flight) method based on infrared light.

[0085] A direct ToF method can be applied as a distance measuring device, which calculates distance by directly determining the time it takes for reflected light Lr obtained when irradiated light Li is reflected by an object Ob to return. Alternatively, an indirect ToF method can be applied as a distance measuring device, which calculates the distance to the object Ob based on the phase difference between the irradiated light Li toward the object Ob and the reflected light Lr obtained when the irradiated light Li is reflected by the object Ob.

[0086] In addition, the indirect ToF method can employ a CAPD (Current Assisted Photonic Demodulator) method, in which a voltage is applied directly to a sensor substrate to generate a current in the substrate, thereby enabling high-speed modulation of a wide area within the substrate, or a Gate method, in which two transfer transistors and two charge accumulation units (floating diffusions) are provided for one photodiode, and charges generated by photoelectric conversion in the photodiode are alternately accumulated in the charge accumulation units by the transfer transistors. Note that the CAPD method and the Gate method are well-known technologies, and detailed description will be omitted, but the CAPD method is disclosed, for example, in Japanese Patent Laid-Open No. 2018-117118, and the Gate method is disclosed, for example, in Japanese Patent Laid-Open No. 2020-013909.

[0087] <8. Variations> FIG. 23 is a diagram illustrating a modified example of the formation range of the infrared light pass filter 32. In FIG. As described above, the infrared light pass filter 32 is formed over at least the entire surface of the effective pixel region 21. However, as shown in Fig. 23, the infrared light pass filter 32 may be formed excluding some of the effective pixels 24 arranged in the effective pixel region 21. In this case, the same material as that of the microlenses 34 is applied to the region 101 where the infrared light pass filter 32 is not provided.

[0088] In this way, the pixel array unit 11 only needs to have the infrared light pass filter 32 formed across at least a plurality of adjacent pixels Px, and the infrared light pass filter 32 does not have to be formed over the entire surface of the effective pixel region 21. However, when the infrared light pass filter 32 is formed over the entire surface of the effective pixel region 21, the effects of color mixing and flare can be suppressed more effectively than when the infrared light pass filter 32 is not formed in part of the effective pixel region 21, and the detection accuracy of infrared light can be improved.

[0089] Fig. 24 is a diagram illustrating a modified example of an infrared light pass filter. The above-described infrared light pass filter 32 is a single layer of organic resin composition containing a color material that cuts visible light dispersed in an organic resin. However, as shown in Fig. 24, the infrared light pass filter 110 may be configured by laminating a color filter 111 that cuts light of red wavelengths and a color filter 112 that cuts light of blue wavelengths. Even in this case, the infrared light pass filter 110 can cut visible light and transmit infrared light.

[0090] 25 to 28 are diagrams illustrating modified examples of the pixel array section. The infrared light pass filter 32 is formed on and in contact with the semiconductor substrate 31, but as shown in Fig. 25, in the pixel array section 120, an organic planar film 121 is formed on the semiconductor substrate 31, and the infrared light pass filter 32 is formed on the organic planar film 121. In this way, the infrared light pass filter 32 may be formed directly on the semiconductor substrate 31, or may be formed on the semiconductor substrate 31 via another member (here, the organic planar film 121).

[0091] 26, the pixel array section 130 may have a microlens 34 formed on a semiconductor substrate 31, and an infrared light pass filter 131 formed on the microlens 34.

[0092] Also, as shown in FIG. 27, in the pixel array section 140, the infrared light pass filter 141 is integrally formed from the same material (for example, an organic resin composition) as the microlens 142, and functions as an infrared light pass filter that cuts out visible light and transmits infrared light, and may also function as a microlens.

[0093] 28, in the pixel array section 150, a polarizing element 151 may be formed between the semiconductor substrate 31 and the infrared light pass filter 32. The polarizing element 151 may be formed of a metal film (wire grid) such as Al.

[0094] <9. Summary of embodiments> As described above, the photodetector 1 according to the embodiment includes a substrate (semiconductor substrate 31) on which a plurality of light receiving sections (photodiodes PD) are arranged in pixel units, and a filter (infrared light pass filter 32) formed on the substrate across a plurality of adjacent pixels, which blocks visible light and transmits infrared light. This makes it possible for the light receiving section of each pixel to receive infrared light with reduced wavelength variation due to differences in the angle of incidence of the light. Therefore, the photodetector 1 can reduce the influence of the incident angle of light and improve the detection accuracy of infrared light.

[0095] In the photodetector element 1, the filter may be formed over the entire surface of the effective pixel region 21 in which the effective pixels 24 that detect infrared light are arranged (see FIG. 7). This makes it possible for the light receiving section of at least one effective pixel arranged in the effective pixel area to receive infrared light with reduced wavelength change due to differences in the angle of incidence of the light. Therefore, the photodetector 1 can improve the detection accuracy of infrared light in all of the effective pixels 24 arranged in the effective pixel area 21.

[0096] In the photodetector element 1, the filter may be formed over the entire surface of the dummy pixel region 22 in which the dummy pixels 25 provided outside the effective pixel region 21 are arranged (see FIG. 8). As a result, visible light is also cut off in the dummy pixel region 22, so that color mixing from the dummy pixels 25 and visible light reflected by the dummy pixel region 22 can be reduced. Therefore, the photodetector 1 can further improve the detection accuracy of infrared light by reducing color mixing from the dummy pixels 25 and flare caused by visible light.

[0097] In the photodetector element 1, the filter may be formed on the entire surface of the light-shielded pixel region 23, which is provided outside the dummy pixel region 22 and in which the light-shielded pixels 26 are arranged (see FIG. 9). As a result, visible light is also blocked in the light-shielded pixel region 23, so that the visible light reflected in the light-shielded pixel region 23 can be reduced. Therefore, by reducing the visible light reflected by the light-shielded pixel region 23 where the light-shielded pixels 26 are formed and further reducing the flare caused by visible light, it is possible to further improve the detection accuracy of infrared light.

[0098] In the photodetector element 1, the filter may be formed on the entire surface of the substrate (see FIG. 10). This makes it possible to reduce visible light reflected on the substrate. Therefore, by reducing the visible light reflected on the substrate and further reducing flare caused by visible light, it is possible to further improve the detection accuracy of infrared light.

[0099] In the photodetector element 1, the filter may be made of a material in which a coloring material that cuts visible light is dispersed in an organic resin. This makes it possible to reduce the influence of the angle of incidence of incident light. Therefore, the detection accuracy of infrared light can be improved regardless of the incident angle of light.

[0100] In the photodetector element 1, the filter (infrared light pass filter 141) is made of the same material as the microlens 142 that focuses light onto the pixel, and is considered to be formed integrally with the microlens 142 (see FIG. 27). This makes it possible to form the filter and the microlens at the same time. Therefore, the time and cost required to form the filters and microlenses can be reduced.

[0101] Furthermore, the photodetector 1 may be provided with a microlens 34 formed on the substrate to focus light onto the light receiving portion, and the filter may be formed on the microlens 34 formed on the substrate (see FIG. 26). This allows the microlens 34 to focus only infrared light.

[0102] In the photodetector element 1, the filter may be formed so as to exclude some of the effective pixels 24 within the effective pixel region 21 (see FIG. 23). This allows some of the effective pixels 24 to receive visible light. Therefore, visible light can be detected in some pixels, and information based on the visible light can be obtained.

[0103] Furthermore, the photodetector element 1 may be provided with a light-shielding film (light-shielding organic film 43) that is formed outside the effective pixel area 21 and cuts at least infrared light, and the filter may be formed closer to the substrate (semiconductor substrate 31) than the light-shielding film (see FIG. 11). This makes it possible to reduce reflection of infrared light outside the effective pixel area 21 as well. Therefore, the detection accuracy of infrared light can be further improved.

[0104] Furthermore, the photodetector element 1 may be provided with a light-shielding film (light-shielding organic film 43) that is formed outside the effective pixel area 21 and cuts at least infrared light, and the filter may be formed at a position farther away from the substrate (semiconductor substrate 31) than the light-shielding film (see FIG. 12). This makes it possible to reduce reflection of infrared light outside the effective pixel area 21 as well. Therefore, the detection accuracy of infrared light can be further improved.

[0105] In the light-detecting element 1, the light-shielding film (light-shielding organic film 43) is considered to cut visible light. This also makes it possible to further reduce the reflection of visible light. Therefore, the detection accuracy of infrared light can be further improved.

[0106] In the light-detecting element 1, the light-shielding film (light-shielding organic film 43) may be made of a material in which a coloring material that blocks visible light is dispersed in an organic resin. This makes it possible to reduce the influence of the angle of incidence of incident light. Therefore, the detection accuracy of infrared light can be further improved.

[0107] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0108] <10. This Technology> The present technology can also be configured as follows. (1) a substrate on which a plurality of light receiving units are arranged in pixel units; a filter formed on the substrate across a plurality of adjacent pixels, the filter cutting visible light and transmitting infrared light; A photodetector element comprising: (2) The filter is formed over the entire surface of an effective pixel area in which effective pixels for detecting the infrared light are arranged. The photodetector element according to (1). (3) The filter is formed on the entire surface of a dummy pixel area in which dummy pixels provided outside the effective pixel area are arranged. The photodetector element according to (2). (4) The filter is formed on the entire surface of a light-shielding pixel region in which light-shielding pixels provided outside the dummy pixel region are arranged. The photodetector element according to (3). (5) The filter is formed on the entire surface of the substrate. A photodetector according to any one of (1) to (4). (6) The filter is made of an organic resin composition in which a coloring material that cuts visible light is dispersed in the organic resin. A photodetector according to any one of (1) to (5). (7) The filter is made of the same material as the microlens that focuses light onto the light receiving portion, and is formed integrally with the microlens. A photodetector according to any one of (1) to (6). (8) a microlens formed on the substrate for condensing light onto the light receiving portion; The filter is formed on a microlens formed on the substrate. A photodetector according to any one of (1) to (7). (9) The filter is formed by excluding some of the effective pixels within the effective pixel area. A photodetector according to any one of (1), (5) to (7). (10) a light-shielding film formed outside the effective pixel area and blocking at least infrared light; The filter is formed closer to the substrate than the light-shielding film. A photodetector according to any one of (1) to (9). (11) a light-shielding film formed outside the effective pixel area and blocking at least infrared light; The filter is formed at a position farther from the substrate than the light-shielding film. A photodetector according to any one of (1) to (9). (12) The light-shielding film blocks visible light and infrared light. The photodetector according to (10) or (11). (13) The light-shielding film is made of an organic resin composition in which a coloring material that blocks visible light is dispersed in an organic resin. The photodetector according to (10) or (11). [Explanation of symbols]

[0109] 1. Photodetector element 21 Effective pixel area 22 Dummy pixel area 23 Light-shielding pixel area 24 effective pixels 25 dummy pixels 26 Light-shielding pixels 31 Semiconductor substrate 32 Infrared light pass filter 33 Separation wall 34 Microlens

Claims

1. a substrate provided with an effective pixel area in which effective pixels that detect infrared light are arranged, a dummy pixel area provided outside the effective pixel area in which dummy pixels are arranged, and a light-shielding pixel area provided outside the dummy pixel area in which light-shielding pixels are arranged; a filter formed on the substrate over the entire surfaces of the effective pixel region, the dummy pixel region, and the light-shielding pixel region, the filter blocking visible light and transmitting infrared light; a first light-shielding film formed in the light-shielding pixel region on the substrate side relative to the filter, and shielding the light-shielding pixels from light; a second light-shielding film that is formed in the light-shielding pixel region on the opposite side of the substrate from the filter and that blocks at least infrared light; A photodetector element comprising:

2. The filter is made of an organic resin composition in which a coloring material that cuts visible light is dispersed in the organic resin. The photodetector element according to claim 1 .

3. The second light-shielding film blocks visible light and infrared light. The photodetector element according to claim 1 .

4. The second light-shielding film is made of an organic resin composition in which a coloring material that blocks visible light is dispersed in an organic resin. The photodetector element according to claim 3 .

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