WO2024111271A1

WO2024111271A1 - Light detector and electronic appliance

Info

Publication number: WO2024111271A1
Application number: PCT/JP2023/036790
Authority: WO
Inventors: 貴大矢田; 尊明下村; 有志井芹; 和弘大澤; 大輔萩原; 淳平田中
Original assignee: ソニーセミコンダクタソリューションズ株式会社
Priority date: 2022-11-21
Filing date: 2023-10-10
Publication date: 2024-05-30

Abstract

Provided is a light detector capable of more adequately reducing incident light. Specifically, the light detector has a configuration comprising a semiconductor substrate having a plurality of photoelectric conversion parts formed thereon, a plurality of light-collecting parts disposed on the light-entrance-surface side of the semiconductor substrate and having on-chip lenses, and a light reduction structure disposed between some of the on-chip lenses and the semiconductor substrate and having a light-shielding pattern consisting of transmission regions for transmitting light and light-shielding regions for shielding some of the light, wherein the light convergence spot attributable to each light-collecting part is separated from the light reduction structure along a direction orthogonal to the light entrance surface of the semiconductor substrate.

Description

Photodetection device and electronic device

This disclosure relates to a light detection device and electronic equipment.

　In the past, in order to realize a high dynamic range of an image sensor, a photodetection device has been proposed that introduces a light-attenuating structure that generates a sensitivity difference between pixels. For example, the photodetection device described in Patent Document 1 describes a configuration in which a polarizer having multiple wires arranged in parallel with each other is disposed as a light-attenuating structure between an on-chip lens and a photoelectric conversion unit.

JP 2011-526105 A

In such photodetection devices, there is a need to more appropriately attenuate the incoming light.

The present disclosure aims to provide a light detection device and electronic device that can more appropriately attenuate incident light.

The photodetector disclosed herein comprises (a) a semiconductor substrate on which multiple photoelectric conversion units are formed, (b) multiple focusing units each having an on-chip lens and disposed on the light incident surface side of the semiconductor substrate, and (c) a light-attenuating structure disposed between some of the on-chip lenses and the semiconductor substrate and having a light-shielding pattern with a light-transmitting region that transmits light and a light-shielding region that blocks some of the light, and (d) a light-focusing spot of light generated by the focusing units and the light-attenuating structure are separated from each other in a direction perpendicular to the light incident surface of the semiconductor substrate.

Another photodetector device disclosed herein includes (a) a semiconductor substrate on which multiple photoelectric conversion units are formed, (b) multiple light-collecting units each having an on-chip lens and disposed on the light-incident surface side of the semiconductor substrate, and (c) a light-attenuating structure disposed between some of the on-chip lenses and the semiconductor substrate, and having a light-shielding pattern with a light-transmitting region that transmits light and a light-shielding region that blocks some of the light, and (d) the light-shielding pattern has a portion in which the proportion of the light-shielding region is different from other portions.

The electronic device disclosed herein comprises (a) a semiconductor substrate on which multiple photoelectric conversion units are formed, (b) multiple focusing units each having an on-chip lens and disposed on the light incident surface side of the semiconductor substrate, (c) and a light-attenuating structure disposed between some of the on-chip lenses and the semiconductor substrate and having a light-shielding pattern with a light-transmitting region that transmits light and a light-shielding region that blocks some of the light, and (d) a light detection device in which the light-focusing spot of the focusing units and the light-attenuating structure are separated from each other in a direction perpendicular to the light incident surface of the semiconductor substrate.

1 is a diagram showing an overall configuration of a solid-state imaging device according to a first embodiment; 2 is a diagram showing a cross-sectional configuration of the solid-state imaging device taken along line AA in FIG. 1. 1 is a diagram showing a cross-sectional configuration of a solid-state imaging device when broken at the position of a light incidence surface of a light-attenuating structural body. FIG. 13 is a diagram showing the overall configuration of a solid-state imaging device when a light-attenuating structural body is disposed at a position overlapping with a focused spot. FIG. 5 is a diagram showing a light blocking pattern and an incidence area of the light attenuation structural body at the position of a light incidence surface of the light attenuation structural body shown in FIG. 4 . FIG. 1 is a diagram showing the overall configuration of a solid-state imaging device in which a light-attenuating structural body is disposed at a position overlapping with a focused spot when light is incident from an oblique direction; FIG. 7 is a diagram showing a light blocking pattern and an incidence area of the light attenuation structural body at the position of the light incidence surface of the light attenuation structural body shown in FIG. 6 . FIG. FIG. 4 is a diagram showing the relationship between the incident angle of light and sensitivity. 1 is a diagram showing the overall configuration of a solid-state imaging device when light is incident from an oblique direction. 10 is a diagram showing a light blocking pattern and an incidence area of the light attenuation structural body at the position of a light incidence surface of the light attenuation structural body shown in FIG. 9 . FIG. FIG. 4 is a diagram showing the relationship between the incident angle of light and sensitivity. FIG. 11 is a diagram showing a method for adjusting the degree of light attenuation. FIG. 11 is a diagram showing a method for adjusting the degree of light attenuation. FIG. 13 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 4 is a diagram showing the relationship between the incident angle of light and sensitivity. FIG. 13 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 13 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 13 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 13 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. 13 is a diagram showing a light blocking pattern of a light attenuation structural body at the position of a light incident surface of the light attenuation structural body according to the modified example. FIG. 13 is a diagram showing a light blocking pattern of a light attenuation structural body at the position of a light incident surface of the light attenuation structural body according to the modified example. FIG. 13 is a diagram showing a light blocking pattern of a light attenuation structural body at the position of a light incident surface of the light attenuation structural body according to the modified example. FIG. 13 is a diagram showing a light blocking pattern of a light attenuation structural body at the position of a light incident surface of the light attenuation structural body according to the modified example. FIG. FIG. 11 is a diagram showing an overall configuration of an electronic device according to a second embodiment.

An example of a light detection device and an electronic device according to an embodiment of the present disclosure will be described below with reference to FIGS. 1 to 24. The embodiments of the present disclosure will be described in the following order. Note that the present disclosure is not limited to the following examples. In addition, the effects described in this specification are examples and are not limiting, and other effects may also be present.
1. First embodiment: solid-state imaging device 1-1 Overall configuration of solid-state imaging device 1-2 Configuration of main parts 1-3 Modifications 2. Second embodiment: Application to electronic devices

1. First embodiment: solid-state imaging device
[1-1 Overall configuration of solid-state imaging device]
A solid-state imaging device 1 (or, in a broader sense, a "photodetector") according to a first embodiment of the present disclosure will be described below. Fig. 1 is a diagram showing an overall configuration of the solid-state imaging device 1 according to the first embodiment.
The solid-state imaging device 1 in Fig. 1 is a back-illuminated CMOS (Complementary Metal Oxide Semiconductor) image sensor. As shown in Fig. 24, the solid-state imaging device 1 (1002) captures image light (incident light) from a subject via a lens group 1001, converts the amount of incident light focused on an imaging surface into an electrical signal on a pixel-by-pixel basis, and outputs the electrical signal.
As shown in FIG. 1, the solid-state imaging device 1 includes a pixel region 2, a vertical drive circuit 3, a column signal processing circuit 4, a horizontal drive circuit 5, an output circuit 6, and a control circuit .

The pixel region 2 has a plurality of pixels 8 arranged in a two-dimensional array. Each pixel 8 has a photoelectric conversion unit 22 (see FIG. 2) and a plurality of pixel transistors (e.g., a transfer transistor, a reset transistor, an amplification transistor, and a selection transistor). In order to realize a high dynamic range of the image sensor, the pixels 8 have two types of pixels: a high sensitivity pixel 8H and a low sensitivity pixel 8L having a lower sensitivity than the high sensitivity pixel 8H.
The vertical drive circuit 3 is configured, for example, by a shift register, and sequentially selects each pixel 8 in the pixel region 2 on a row-by-row basis by, for example, sequentially outputting selection pulses to pixel drive wirings 9, and outputs pixel signals of the selected pixels 8 to the column signal processing circuit 4 through vertical signal lines 10. The pixel signals are signals obtained by electricity (for example, electrons) generated in the photoelectric conversion units 22.

The column signal processing circuit 4 is arranged, for example, for each column of pixels 8, and performs signal processing such as noise removal for each pixel column on signals output from one row of pixels 8. For example, correlated double sampling (CDS) for removing fixed pattern noise specific to each pixel and AD (Analog-Digital) conversion can be used as the signal processing.
The horizontal drive circuit 5 is, for example, composed of a shift register, and sequentially outputs horizontal scanning pulses to the column signal processing circuits 4, selects the column signal processing circuits 4 in order, and causes the selected column signal processing circuit 4 to output pixel signals that have been subjected to signal processing to the horizontal signal line 11.

The output circuit 6 performs various signal processing on each of the pixel signals sequentially output from the column signal processing circuit 4 through the horizontal signal line 11. As the signal processing, various types of digital signal processing such as buffering, black level adjustment, column variation correction, etc. can be used.
The control circuit 7 generates clock signals and control signals that serve as a reference for the operation of the vertical drive circuit 3, the column signal processing circuit 4, the horizontal drive circuit 5, etc., based on the vertical synchronization signal, the horizontal synchronization signal, and the master clock signal. Then, the control circuit 7 outputs the generated clock signals and control signals to the vertical drive circuit 3, the column signal processing circuit 4, the horizontal drive circuit 5, etc.

[1-2 Configuration of main parts]
Next, there will be described a detailed structure of the solid-state imaging device 1. Fig. 2 is a diagram showing a cross-sectional configuration of the solid-state imaging device 1 taken along line AA in Fig. 1.
As shown in Fig. 2, the solid-state imaging device 1 has an insulating film 13, a light-shielding film 14, a planarizing film 15, an inner lens 16, a planarizing film 17, a color filter 18, and an on-chip lens 19 laminated in this order on a light incident surface (hereinafter also referred to as "back surface S1") of a semiconductor substrate 12. A wiring layer 20 is disposed on a surface (hereinafter also referred to as "front surface S2") opposite to the back surface S1 of the semiconductor substrate 12. Also, of the pixels 8 (high sensitivity pixel 8H, low sensitivity pixel 8L) of the solid-state imaging device 1, a light-shielding structure 21 having a predetermined light-shielding pattern (see Fig. 5) is disposed immediately below the color filter 18 in the portion of the low sensitivity pixel 8L. That is, the light-shielding structure 21 is disposed between some of the on-chip lenses 19 and the semiconductor substrate 12.

The semiconductor substrate 12 is made of, for example, a silicon (Si) substrate. A photoelectric conversion unit 22 is formed in each region of the semiconductor substrate 12 where each pixel 8 is located. That is, a plurality of photoelectric conversion units 22 are arranged in a two-dimensional array on the semiconductor substrate 12. The photoelectric conversion unit 22 has a p-type semiconductor region and an n-type semiconductor region, and the pn junction between these forms a photodiode, which performs photoelectric conversion to generate charge according to the amount of light received. The photoelectric conversion unit 22 also accumulates the charge generated by photoelectric conversion in the electrostatic capacitance generated by the pn junction.

The insulating film 13 continuously covers the entire back surface S1 side of the semiconductor substrate 12. The insulating film 13 may be made of a material such as silicon oxide (SiO ₂ ) or silicon nitride (SiN).
The light-shielding film 14 is formed in a lattice shape on a part of the light incident surface (hereinafter also referred to as "rear surface S3") side of the insulating film 13 so as to open the light incident surface (rear surface S1) of each of the multiple photoelectric conversion units 22. That is, the light-shielding film 14 is disposed on the rear surface S1 side of the semiconductor substrate 12, and is formed so as to cover the region between adjacent photoelectric conversion units 22 in a plan view. As the material for the light-shielding film 14, for example, a metal such as aluminum (Al), tungsten (W), or copper (Cu) can be used.
The planarization film 15 covers the rear surface S3 of the insulating film 13 and the light-shielding film 14, and makes the surface on the inner lens 16 side (hereinafter also referred to as the "rear surface S4") a flat surface without any irregularities. Examples of the material for the planarization film 15 include silicon oxide ( _SiO2 ) and silicon nitride (SiN).

The inner lenses 16 are arranged in a two-dimensional array so as to correspond to each pixel 8. The inner lenses 16 collect light transmitted through the on-chip lenses 19 and cause the collected transmitted light to enter the corresponding photoelectric conversion unit 22. The inner lenses 16, together with the on-chip lenses 19, form a light collecting unit 24 that collects incident light (hereinafter also referred to as "light 23") for each pixel 8. This results in a configuration in which a plurality of light collecting units 24 having the on-chip lenses 19 and the inner lenses 16 arranged between the semiconductor substrate 12 and the on-chip lenses 19 are arranged on the rear surface S1 side of the semiconductor substrate 12. FIG. 2 illustrates a case in which the position of a light collecting spot 25 of the light 23 by the light collecting unit 24 is located at a depth where the light shielding film 14 is arranged in a direction perpendicular to the rear surface S1 of the semiconductor substrate 12 (the vertical direction in FIG. 2). That is, in a direction perpendicular to the rear surface S 1 of the semiconductor substrate 12 , a light spot 25 of the light 23 focused by the light focusing portion 24 is positioned closer to the semiconductor substrate 12 than the light attenuation structural body 21 .
The planarization film 17 covers the light incidence surface (hereinafter also referred to as the "rear surface S5") of the inner lens 16, and makes the surface on the color filter 18 side (hereinafter also referred to as the "rear surface S6") a flat surface without irregularities. The planarization film 17 can be made of the same material as the planarization film 15, for example.

In addition, the planarization film 15, the inner lens 16, and the planarization film 17 are partitioned into a plurality of regions corresponding to the pixels 8, and a partition wall 27 is disposed between adjacent regions. That is, the partition wall 27 is formed in a lattice shape so as to surround each region. This makes it possible to suppress the light 23 incident on a certain region from leaking out to an adjacent region, thereby suppressing optical color mixing. In addition, the end of the partition wall 27 on the semiconductor substrate 12 side is in contact with the light-shielding film 14 and is electrically connected to the light-shielding film 14. For example, metals such as aluminum (Al), tungsten (W), and copper (Cu) can be used as the material of the partition wall 27. When the same metal as the light-shielding film 14 is used as the material of the partition wall 27, the partition wall 27 and the light-shielding film 14 may be formed integrally.
The color filters 18 are arranged in a two-dimensional array so as to correspond to each pixel 8. FIG. 2 illustrates a case where a shared color filter 18 is arranged between the high-sensitivity pixel 8H and the low-sensitivity pixel 8L. The color filter 18 transmits only light of a predetermined wavelength different from each other. For example, an R filter that transmits red light, a G filter that transmits green light, and a B filter that transmits blue light can be given. As a result, the color filter 18 transmits light of a predetermined wavelength according to the transmission characteristics, and the transmitted light is made incident on the corresponding photoelectric conversion unit 22. Note that FIG. 2 illustrates a case where a G filter is used as the color filter 18 shared between the high-sensitivity pixel 8H and the low-sensitivity pixel 8L, but is not limited thereto. For example, an R filter or a B filter may be used, and a color filter other than RGB may be used.
The on-chip lenses 19 are arranged in a two-dimensional array so as to correspond to each pixel 8. The on-chip lenses 19 collect image light (light 23) from a subject, and cause the collected image light (light 23) to enter the corresponding photoelectric conversion unit 22 via the color filter 18 or the like.
The wiring layer 20 is disposed on the surface S2 side of the semiconductor substrate 12. The wiring layer 20 has an interlayer insulating film and wirings stacked in multiple layers with the interlayer insulating film interposed therebetween. The wiring layer 20 drives pixel transistors (not shown) of each pixel 8 via the multiple layers of wiring.

The light-reducing structure 21 is disposed between the inner lens 16 and the color filter 18, and is formed so as to cover the entire surface (hereinafter also referred to as "surface S7") of the color filter 18 on the planarization film 17 side in the low-sensitivity pixel 8L. As a result, in a direction perpendicular to the back surface S1 of the semiconductor substrate 12 (the vertical direction in FIG. 2), the light-condensing spot 25 of the light-condensing portion 24 and the light-reducing structure 21 are configured to be separated from each other. FIG. 2 illustrates a case in which the light-reducing structure 21 is disposed directly below the color filter 18. As the light-reducing structure 21, a structure having a light-shielding pattern by a transmission region 30 that transmits light and a light-shielding region 31 that partially blocks light is used. As a result, the light-reducing structure 21 attenuates the light 23 according to the light-shielding pattern, and causes the attenuated light 23 to enter the inner lens 16. As an example of the light-reducing structure 21, for example, as shown in FIG. 3, a mesh-shaped structure 21a in which a mesh-shaped light-shielding pattern is formed by the transmission region 30 and the light-shielding region 31 can be adopted. 3 illustrates an example of a mesh-shaped light-shielding pattern in which, in a plan view, a frame formed of a frame-shaped light-shielding region 31 is arranged in the outer edge region, and two linear band-shaped light-shielding regions 31 extending along the vertical and horizontal directions are arranged at a constant pitch in the inner region surrounded by the frame, thereby arranging opening regions (transmitting regions 30) in a two-dimensional matrix of 3×3. As a result, in the mesh-shaped structure 21a, the ratio of the transmitting region 30 to the light-shielding region 31 is constant in the entire region of the mesh-shaped structure 21a. In addition, the outer periphery of the mesh-shaped structure 21a is in contact with the side surface of the partition wall 27 and is electrically connected to the partition wall 27. FIG. 3 is a diagram showing a cross-sectional configuration of the solid-state imaging device 1 when the light-attenuating structure 21 is broken at the position of the rear surface S8. As the material of the light-attenuating structure 21, for example, metals such as aluminum (Al), tungsten (W), and copper (Cu), and light-absorbing materials such as black resin can be used. For example, if a light absorbing material is used, reflection of light 23 by the dimming structure 21 can be suppressed, reducing the possibility of flare caused by reflected light.

In the solid-state imaging device 1 having the above configuration, when light 23 is incident on the high-sensitivity pixel 8H, the incident light 23 passes through the on-chip lens 19, the color filter 18, and the inner lens 16, and the transmitted light 23 is photoelectrically converted in the photoelectric conversion unit 22 to generate a signal charge. The generated signal charge is then output as a pixel signal from the vertical signal line 10 in FIG. 1 formed by the wiring of the wiring layer 20. Also, when light 23 is incident on the low-sensitivity pixel 8L, the incident light 23 passes through the on-chip lens 19, the color filter 18, the inner lens 16, and also the light-reducing structure 21 to be incident on the photoelectric conversion unit 22. Therefore, the sensitivity of the low-sensitivity pixel 8L is lower than that of the high-sensitivity pixel 8H. This allows a sensitivity difference to be created between the low-sensitivity pixel 8L and the high-sensitivity pixel 8H, and a high dynamic range of the image sensor can be realized by using the pixel signal of the high-sensitivity pixel 8H and the pixel signal of the low-sensitivity pixel 8L.

Here, for example, as shown in FIG. 4, consider a configuration in which the light attenuation structure 21 is disposed at a depth where the light-shielding film 14 is located, and the light-focusing spot 25 of the light 23 by the light-focusing unit 24 overlaps with the position of the light attenuation structure 21 in a direction perpendicular to the back surface S1 of the semiconductor substrate 12 (the vertical direction in FIG. 4). In such a configuration, the diameter of the region of the light attenuation structure 21 where the light 23 hits (hereinafter also referred to as the "irradiation region 26") becomes smaller than the width of the transmission region 30 and the width of the light-shielding region 31. Therefore, for example, as shown in FIG. 4 and FIG. 5, when the incidence angle (CRA) of the light 23 becomes a predetermined angle, the light-focusing spot 25 of the light 23 is located within the transmission region 30 of the light attenuation structure 21, and the light 23 passes through the transmission region 30 as it is, and the light 23 is incident on the photoelectric conversion unit 22. FIG. 5 is a diagram showing the light shielding pattern and the irradiation area 26 of the light attenuation structure 21 at the position of the light incident surface (hereinafter, "rear surface S8") of the light attenuation structure 21 shown in FIG. 4.

Also, for example, when the angle of incidence of the light 23 is changed from the above-mentioned predetermined angle, the condensed spot 25 of the light 23 moves laterally, and when the condensed spot 25 of the light 23 moves to a position where it overlaps with the light-shielding region 31 of the light-attenuating structure 21 as shown in Figs. 6 and 7, most of the light 23 is blocked by the light-shielding region 31, and only a small amount of the light 23 that has passed through the surrounding transparent region 30 is incident on the photoelectric conversion unit 22. Fig. 7 is a diagram showing the light-shielding pattern and the irradiation region 26 of the light-attenuating structure 21 at the position of the back surface S8 of the light-attenuating structure 21 shown in Fig. 6. Such a change in the amount of light 23 incident on the photoelectric conversion unit 22 occurs periodically according to the change in the angle of incidence of the light 23, since it is due to the position of the light-attenuating spot 25 and the light-shielding pattern of the light-attenuating structure 21. Therefore, the change in the amount of light 23 incident on the photoelectric conversion unit 22 causes the sensitivity of the pixel 8 (low-sensitivity pixel 8L) to change periodically according to the angle of incidence of the light 23, as shown in Fig. 8. Therefore, in the solid-state imaging device 1 having the configuration shown in FIG. 4, even if the pixel 8 (low-sensitivity pixel 8L) uses the same light-attenuating structure 21, the sensitivity of the pixel 8 (low-sensitivity pixel 8L) may vary depending on its position within the pixel region 2, which may result in a deterioration in the image quality of the captured image.

In contrast, in the first embodiment, the condensed spot 25 of the light 23 by the condensing unit 24 and the light attenuation structure 21 are separated from each other in the direction perpendicular to the back surface S1 of the semiconductor substrate 12 (the vertical direction in FIG. 2). As a result, the region (irradiation region 26) of the light attenuation structure 21 on which the light 23 hits can be made larger than when, for example, the light attenuation structure 21 is disposed at a depth where the light shielding film 14 is located (the configuration shown in FIG. 4). Therefore, the diameter of the irradiation region 26 can be made larger than the width of the transmission region 30 and the width of the light shielding region 31. Therefore, for example, as shown in FIG. 2, FIG. 3, FIG. 9, and FIG. 10, the variation in the ratio of the transmission region 30 and the ratio of the light shielding region 31 included in the irradiation region 26 when the angle of incidence of the light 23 is changed can be suppressed. FIG. 2 and FIG. 3 are diagrams showing the case where the angle of incidence of the light 23 is the same as the light 23 shown in FIG. 4, and FIG. 9 and FIG. 10 are diagrams showing the case where the angle of incidence of the light 23 is the same as the light 23 shown in FIG. 6.
As a result, the change in the amount of light 23 incident on the photoelectric conversion unit 22 according to the change in the angle of incidence of the light 23 can be suppressed, and as shown in FIG. 11, the periodic change in the sensitivity of the pixel 8 (low-sensitivity pixel 8L) according to the angle of incidence of the light 23 can be suppressed. Therefore, according to the solid-state imaging device 1 according to the first embodiment, it is possible to more appropriately attenuate the incident light (light 23). Therefore, the change in the sensitivity of the pixel 8 (low-sensitivity pixel 8L) according to the position in the pixel region 2 can be suppressed, and the deterioration of the image quality of the captured image can be suppressed. FIG. 10 is a diagram showing the light-shielding pattern and the irradiation region 26 of the light-attenuating structure 21 at the position of the back surface S8 of the light-attenuating structure 21 shown in FIG. 9.
In the first embodiment, the light is reduced using the light-reducing structure 21 having a light-shielding pattern made up of the transmission region 30 and the light-shielding region 31. Therefore, unlike a configuration in which light is reduced using a gray filter, for example, light can be reduced without changing the spectrum.

In the first embodiment, the light attenuation structure 21 is configured to use a mesh-like structure 21a that forms a mesh-like light-shielding pattern by means of transmissive regions 30 and light-shielding regions 31. Therefore, the degree of attenuation of light 23 by the light attenuation structure 21 can be adjusted by changing the width of the line-like portions (light-shielding regions 31) that make up the mesh and the width of the openings (transmissive regions 30), as shown in FIG. 12, for example. Alternatively, it can also be adjusted by changing the number of line-like portions (light-shielding regions 31) and the number of openings (transmissive regions 30), as shown in FIG. 13, for example.

[1-3 Modifications]
(1) In the first embodiment, the light-reducing structure 21 is disposed between the inner lens 16 and the color filter 18, but other configurations may be adopted. For example, as shown in FIG. 14, the light-reducing structure 21 may be disposed between the semiconductor substrate 12 and the inner lens 16, and may be formed to cover the entire surface (hereinafter, also referred to as "surface S9") of the inner lens 16 on the planarization film 15 side in the low-sensitivity pixel 8L. FIG. 14 illustrates a case in which the light-reducing structure 21 is disposed directly below the inner lens 16. By disposing the light-reducing structure 21 between the semiconductor substrate 12 and the inner lens 16, for example, compared to the case in which the light-reducing structure 21 is disposed at a depth where the light-shielding film 14 is located (the configuration shown in FIG. 4), the region (irradiation region 26) of the light-reducing structure 21 on which the light 23 hits can be made larger. Therefore, by using the same principle as in the case where the light attenuation structure 21 is disposed between the inner lens 16 and the color filter 18 (the configuration shown in FIG. 2 ), as shown in FIG. 15 , it is possible to suppress periodic changes in the sensitivity of the pixel 8 (low sensitivity pixel 8L) depending on the angle of incidence of the light 23. In addition, according to the configuration shown in FIG. 14 , the light attenuation structure 21 is disposed at a deeper position from the light incidence surface of the on-chip lens 19 than in the configuration shown in FIG. 2 , so that it is possible to weaken the reflected light due to the light 23 reflected by the light attenuation structure 21, and it is possible to reduce the possibility of flare occurring due to the reflected light.
16, for example, the light attenuation structure 21 may be disposed between the on-chip lens 19 and the color filter 18, and may be formed so as to cover the entire light incidence surface (hereinafter also referred to as "surface S10") of the color filter 18 in the low-sensitivity pixel 8L. FIG. 16 illustrates a case in which the light attenuation structure 21 is disposed directly above the color filter 18.

(2) For example, as shown in FIG. 17 and FIG. 18, the light-attenuating structure 21 may be disposed at a depth where the light-shielding film 14 is located, and may be formed to cover the entire light-incident surface (rear surface S3) of the insulating film 13 in the low-sensitivity pixel 8L. FIG. 17 and FIG. 18 show an example in which the light-attenuating structure 21 is formed in a part of the metal film forming the light-shielding film 14. In this case, as shown in FIG. 17, the light-concentrating portion 24 is formed so that the light-concentrating spot 25 of the light 23 by the light-concentrating portion 24 is located within the semiconductor substrate 12 in the direction perpendicular to the rear surface S1 of the semiconductor substrate 12 (the vertical direction in FIG. 17). Alternatively, as shown in FIG. 18, the light-concentrating portion 24 is formed so that the light-concentrating spot 25 of the light 23 by the light-concentrating portion 24 is located closer to the light-concentrating portion 24 than the light-attenuating structure 21 in the direction perpendicular to the rear surface S1 of the semiconductor substrate 12 (the vertical direction in FIG. 18). 17 and 18, the inner lens 16 shown in FIG. 2 is omitted, and the light collecting portion 24 is formed only by the on-chip lens 19. Also, the light collecting portion 24 can be formed only by the on-chip lens 19 in the configuration in which the light attenuation structure 21 is disposed directly under the color filter 18 (the configuration shown in FIG. 2). Also, in the configuration shown in FIG. 2 and the configuration shown in FIG. 14, the light collecting spot 25 of the light 23 by the light collecting portion 24 may be located within the semiconductor substrate 12 in the direction perpendicular to the rear surface S1 of the semiconductor substrate 12.

(3) In the first embodiment, the back surface S1 of the semiconductor substrate 12 is a flat surface, but other configurations can be adopted. For example, as shown in FIG. 19, a plurality of inverted pyramid-shaped recesses 32 may be formed on the back surface S1 side of the semiconductor substrate 12, and a moth-eye structure anti-reflection portion may be provided. In this case, the semiconductor substrate 12 has pixel separation portions 33 disposed between adjacent photoelectric conversion portions 22. The pixel separation portions 33 are formed in a lattice shape so as to surround each of the photoelectric conversion portions 22. Metals such as aluminum (Al), tungsten (W), and copper (Cu) can be used as the material of the pixel separation portions 33. The recesses 32 and the pixel separation portions 33 increase the amount of refraction of the incident light (light 23), and the light 23 is reflected between the pixel separation portions 33, thereby increasing the optical path length. In addition, the reflection of the incident light (light 23) can be prevented, and the light utilization efficiency can be improved. In addition, when the rear surface S1 of the semiconductor substrate 12 has a structure in which a recess 32 is formed, the light-reducing structure 21 is formed at the tip of the inverted pyramid-shaped recess 32. In other words, the tip of the inverted pyramid-shaped recess 32 becomes the light-shielding region 31, and the space between adjacent light-shielding regions 31 becomes the transmission region 30.

(4) In the first embodiment, a mesh-shaped light-shielding pattern is formed on the entire light-attenuating structure 21, and the ratio of the transmission region 30 to the light-shielding region 31 is constant in the entire region of the light-attenuating structure 21. However, other configurations can be adopted. For example, as shown in Figs. 20, 22, and 23, the light-shielding structure 21 may be configured such that the ratio of the transmission region 30 to the light-shielding region 31 differs between the center side 34 and the outer periphery side 35 of the light-attenuating structure 21. This makes it possible to control the degree of attenuation of the light 23 relative to the incidence angle (CRA) of the incident light (light 23), and to more appropriately attenuate the light 23. Figs. 20 to 23 illustrate a case in which the ratio of the light-shielding region 31 on the center side 34 of the light-attenuating structure 21 (hereinafter also referred to as the "first ratio") is greater than the ratio of the light-shielding region 31 on the outer periphery side 35 (hereinafter also referred to as the "second ratio"). By making the first ratio greater than the second ratio, for example, it is possible to improve the sensitivity of the pixel 8 (low sensitivity pixel 8L) on the high image height side where the angle of incidence of the light 23 is larger, and it is possible to prevent the sensitivity of the dimming structure 21 from becoming too low.
FIG. 20 illustrates an example in which the light-attenuating structure 21 is an FZP-like structure 21b in which a light-shielding pattern constituting a Fresnel zone plate (FZP) is formed by a transmission region 30 and a light-shielding region 31. The FZP-like structure 21b is a structure in which annular transmission regions 30 and light-shielding regions 31 are alternately arranged concentrically around a circular light-shielding region 31, and the width of these concentric circles (zones) becomes narrower as they approach the outer periphery. By using the FZP-like structure 21b, a light-attenuating effect can be obtained while maintaining optical symmetry. In addition, since the Fresnel zone plate collects light 23, a color mixing reduction effect can also be obtained.
Also, for example, as shown in Fig. 21, the light-shielding pattern of the FZP-like structure 21b may be a pattern that connects the entire layout as a pattern that is easy to process. Fig. 21 illustrates a case in which a linear light-shielding region 31 that penetrates all of the circular or annular light-shielding regions 31 and is electrically connected to the partition wall 27 is added to the FZP-like structure 21b shown in Fig. 20.

FIG. 22 illustrates a case where the light-attenuating structure 21 is a radial structure 21c in which the transmission region 30 and the light-shielding region 31 form a radial light-shielding pattern extending from the center to the outer periphery of the light-attenuating structure 21. By using the radial structure 21c, it is possible to obtain a light-attenuating effect while maintaining optical symmetry. As an example of the radial structure 21c, as shown in FIG. 22, a structure in which linear band-shaped light-shielding regions 31 are radially arranged along the vertical direction, horizontal direction, right diagonal direction, and left diagonal direction in a plan view is given. In addition, the ends of the linear band-shaped light-shielding regions 31 constituting the radial structure 21c are in contact with the side surfaces of the partition wall 27 and are electrically connected to the partition wall 27. This prevents the light-shielding pattern (light-shielding region 31) of the radial structure 21c from being in a floating state.
23 illustrates an example in which the light attenuation structure 21 is a deformed mesh structure 21d in which a mesh-shaped light-shielding pattern is formed on the central side 34 of the light attenuation structure 21 by the transmission region 30 and the light-shielding region 31, and another light-shielding pattern is formed on the peripheral side 35. By using the deformed mesh structure 21d, the degree of light attenuation of the light 23 incident on the photoelectric conversion unit 22 can be adjusted when the incidence angle (CRA) of the light 23 is small and large, and the sensitivity of the pixel 8 (low-sensitivity pixel 8L) can be adjusted. As an example of the deformed mesh structure 21d, as shown in FIG. 23, a mesh-shaped light-shielding pattern in which the transmission regions 30 are arranged in a two-dimensional matrix of 4×4 is formed on the central side 34, and a light-shielding pattern in which the transmission regions 30 are arranged on the entire peripheral side 35 except for the corners is formed. According to the configuration of this example, the sensitivity of the pixel 8 (low-sensitivity pixel 8L) can be improved when the incidence angle of the light 23 is large.

(5) Furthermore, this technology can be applied to light detection devices in general, including distance measurement sensors that measure distance, also known as ToF (Time of Flight) sensors, in addition to the solid-state imaging device 1 as the image sensor described above. A distance measurement sensor is a sensor that emits light toward an object, detects the reflected light that is reflected back from the surface of the object, and calculates the distance to the object based on the flight time from when the light is emitted to when the reflected light is received. The structure of pixel 8 (low sensitivity pixel 8L) described above can be adopted as the light receiving pixel structure of this distance measurement sensor.

2. Second embodiment: Application example to electronic device
The technology according to the present disclosure (the present technology) may be applied to various electronic devices.
FIG. 24 is a diagram showing an example of a schematic configuration of an imaging device (such as a video camera or a digital still camera) as an electronic device to which the present technology is applied.
24, the imaging device 1000 includes a lens group 1001, a solid-state imaging device 1002 (solid-state imaging device 1 according to the first embodiment), a DSP (Digital Signal Processor) circuit 1003, a frame memory 1004, a monitor 1005, and a memory 1006. The DSP circuit 1003, the frame memory 1004, the monitor 1005, and the memory 1006 are connected to each other via a bus line 1007.

The lens group 1001 guides incident light (image light) from a subject to the solid-state imaging device 1002 , and forms an image on the light incident surface (pixel region) of the solid-state imaging device 1002 .
The solid-state imaging device 1002 is made up of the CMOS image sensor according to the first embodiment described above. The solid-state imaging device 1002 converts the amount of incident light focused on the light incident surface by the lens group 1001 into an electrical signal on a pixel-by-pixel basis and supplies the signal to the DSP circuit 1003 as a pixel signal.
The DSP circuit 1003 performs predetermined image processing on the pixel signals supplied from the solid-state imaging device 1002. Then, the DSP circuit 1003 supplies the image signals after the image processing to a frame memory 1004 on a frame-by-frame basis, and temporarily stores the image signals in the frame memory 1004.
The monitor 1005 is formed of a panel-type display device such as a liquid crystal panel, an organic EL (Electro Luminescence) panel, etc. The monitor 1005 displays an image (moving image) of a subject based on pixel signals in frame units temporarily stored in the frame memory 1004.
The memory 1006 is composed of a DVD, a flash memory, etc. The memory 1006 reads out and records the pixel signals temporarily stored in the frame memory 1004 on a frame-by-frame basis.

The electronic device to which the solid-state imaging device 1 can be applied is not limited to the imaging device 1000, but can also be applied to other electronic devices. In addition, although the solid-state imaging device 1 according to the first embodiment is used as the solid-state imaging device 1002, other configurations can also be adopted. For example, it may be configured to use other light detection devices to which the present technology is applied, such as the solid-state imaging device 1 according to a modified example.

The present disclosure may be configured as follows.
(1)
A semiconductor substrate having a plurality of photoelectric conversion units formed thereon;
a plurality of light collecting units each having an on-chip lens, the light collecting units being disposed on a light incident surface side of the semiconductor substrate;
a light-attenuating structure disposed between a part of the on-chip lenses and the semiconductor substrate, the light-attenuating structure having a light-transmitting region that transmits light and a light-shielding region that partially blocks light,
a spot of light focused by said light focusing portion and said light attenuation structure body are spaced apart from each other in a direction perpendicular to a light incident surface of said semiconductor substrate.
(2)
The light detection device according to (1), wherein a spot of light focused by the light focusing portion is located closer to the semiconductor substrate than the light attenuation structural body in a direction perpendicular to a light incident surface of the semiconductor substrate.
(3)
The light detection device according to (1), wherein a spot of light focused by the light focusing portion is located closer to the light focusing portion than the light attenuation structural body in a direction perpendicular to a light incident surface of the semiconductor substrate.
(4)
the light collecting unit has the on-chip lens and an inner lens disposed between the semiconductor substrate and the on-chip lens,
The light detection device according to any one of (1) to (3), wherein the light-attenuating structure is disposed between the semiconductor substrate and the inner lens.
(5)
the light collecting unit has the on-chip lens and an inner lens disposed between the semiconductor substrate and the on-chip lens,
A color filter is disposed between the inner lens and the on-chip lens,
The light detection device according to any one of (1) to (3), wherein the light-attenuating structure is disposed between the inner lens and the color filter.
(6)
The light detection device according to any one of (1) to (5), wherein the attenuation structure defines a mesh-shaped light blocking pattern by the transmission regions and the light blocking regions.
(7)
The light detection device according to any one of (1) to (5), wherein the attenuation structure body forms a light blocking pattern that constitutes a Fresnel zone plate by the transmission region and the light blocking region.
(8)
The light detection device according to any one of (1) to (5), wherein the attenuation structure body forms a radial light-shielding pattern extending from a center portion to an outer periphery of the attenuation structure body by the transmission region and the light-shielding region.
(9)
The light detection device according to any one of (1) to (5), wherein the attenuation structure has a mesh-shaped light-shielding pattern formed on a central portion side of the attenuation structure by the transmission region and the light-shielding region, and another light-shielding pattern formed on an outer periphery side of the attenuation structure.
(10)
A semiconductor substrate having a plurality of photoelectric conversion units formed thereon;
a plurality of light collecting units each having an on-chip lens, the light collecting units being disposed on a light incident surface side of the semiconductor substrate;
a light-attenuating structure disposed between a part of the on-chip lenses and the semiconductor substrate, the light-attenuating structure having a light-transmitting region that transmits light and a light-shielding region that partially blocks light,
The light-shielding structure has a ratio of the transmission region to the light-shielding region that differs between a central portion and an outer periphery of the light-attenuating structure.
(11)
The light detection device according to (10), wherein the attenuation structure body forms a light blocking pattern that constitutes a Fresnel zone plate by the transmission regions and the light blocking regions.
(12)
The light detection device according to (10), wherein the attenuation structural body forms a radial light blocking pattern extending from a center portion to an outer periphery of the attenuation structural body by the transmission region and the light blocking region.
(13)
The light detection device according to (10), wherein the attenuation structure has a mesh-shaped light-shielding pattern formed on a central portion side of the attenuation structure by the transmission region and the light-shielding region, and another light-shielding pattern formed on an outer periphery side of the attenuation structure.
(14)
1. An electronic device comprising: a photodetector comprising: a semiconductor substrate on which a plurality of photoelectric conversion units are formed; a plurality of light collecting units each having an on-chip lens and disposed on a light incident surface side of the semiconductor substrate; and a light attenuation structure disposed between some of the on-chip lenses and the semiconductor substrate and having a light shielding pattern with a light transmitting region that transmits light and a light shielding region that blocks some of the light, wherein a light collecting spot of light by the light collecting units and the light attenuation structure are separated from each other in a direction perpendicular to the light incident surface of the semiconductor substrate.

1...solid-state imaging device, 2...pixel area, 3...vertical drive circuit, 4...column signal processing circuit, 5...horizontal drive circuit, 6...output circuit, 7...control circuit, 8...pixel, 8H...high sensitivity pixel, 8L...low sensitivity pixel, 9...pixel drive wiring, 10...vertical signal line, 11...horizontal signal line, 12...semiconductor substrate, 13...insulating film, 14...light-shielding film, 15...planarization film, 16...inner lens, 17...planarization film, 18...color filter layer, 19...lens array, 20...wiring layer, 21...light-attenuating structure, 21a...mesh structure, 21b...FZP structure, 21c...radial structure, 21d...deformed mesh structure, 22...photoelectric conversion section, 23...light, 24...light-collecting section, 25...light-collecting spot, 26...irradiation area, 27...partition wall, 30...transmission area, 31...light-shielding area, 32...recess, 33...pixel separation section, 34...center side, 35...periphery side

Claims

A semiconductor substrate having a plurality of photoelectric conversion units formed thereon;
a plurality of light collecting units each having an on-chip lens, the light collecting units being disposed on a light incident surface side of the semiconductor substrate;
a light-attenuating structure disposed between a part of the on-chip lenses and the semiconductor substrate, the light-attenuating structure having a light-transmitting region that transmits light and a light-shielding region that partially blocks light,
a spot of light focused by said light focusing portion and said light attenuation structure body are spaced apart from each other in a direction perpendicular to a light incident surface of said semiconductor substrate.
The light detection device according to claim 1 , wherein a spot of light focused by said light focusing portion is located closer to said semiconductor substrate than said light attenuation structural body in a direction perpendicular to a light incident surface of said semiconductor substrate.
The light detection device according to claim 1 , wherein a spot of light focused by the light focusing portion is located closer to the light focusing portion than the light attenuation structural body in a direction perpendicular to a light incident surface of the semiconductor substrate.
the light collecting unit has the on-chip lens and an inner lens disposed between the semiconductor substrate and the on-chip lens,
The light detection device according to claim 1 , wherein the light-attenuating structure is disposed between the semiconductor substrate and the inner lens.
the light collecting unit has the on-chip lens and an inner lens disposed between the semiconductor substrate and the on-chip lens,
A color filter is disposed between the inner lens and the on-chip lens,
The light detection device according to claim 1 , wherein the light-attenuating structure is disposed between the inner lens and the color filter.
The light detection device according to claim 1 , wherein the attenuation structure defines a mesh-shaped light blocking pattern by the transmission regions and the light blocking regions.
2. The light detection device according to claim 1, wherein the attenuation structure body forms a light blocking pattern that constitutes a Fresnel zone plate by the transmission regions and the light blocking regions.
The light detection device according to claim 1 , wherein the light-attenuating structural body forms a radial light-shielding pattern extending from a center portion to an outer periphery of the light-attenuating structural body by the transmission region and the light-shielding region.
The light detection device according to claim 1 , wherein the attenuation structural body has a mesh-shaped light-shielding pattern formed by the transmission region and the light-shielding region at a central portion of the attenuation structural body, and another light-shielding pattern formed at an outer periphery thereof.
A semiconductor substrate having a plurality of photoelectric conversion units formed thereon;
a plurality of light collecting units each having an on-chip lens, the light collecting units being disposed on a light incident surface side of the semiconductor substrate;
a light-attenuating structure disposed between a part of the on-chip lenses and the semiconductor substrate, the light-attenuating structure having a light-transmitting region that transmits light and a light-shielding region that partially blocks light,
The light-shielding structure has a ratio of the transmission region to the light-shielding region that differs between a central portion and an outer periphery of the light-attenuating structure.
The light detection device according to claim 10 , wherein the attenuation structure body forms a light blocking pattern that constitutes a Fresnel zone plate by the transmission regions and the light blocking regions.
The light detection device according to claim 10 , wherein the light-attenuating structural body forms a radial light-shielding pattern extending from a center portion to an outer periphery of the light-attenuating structural body by the transmission region and the light-shielding region.
The light detection device according to claim 10 , wherein the attenuation structural body has a mesh-shaped light-shielding pattern formed by the transmission region and the light-shielding region at a central portion of the attenuation structural body, and another light-shielding pattern formed at an outer periphery thereof.
1. An electronic device comprising: a photodetector comprising: a semiconductor substrate on which a plurality of photoelectric conversion units are formed; a plurality of light collecting units each having an on-chip lens and disposed on a light incident surface side of the semiconductor substrate; and a light attenuation structure disposed between some of the on-chip lenses and the semiconductor substrate and having a light shielding pattern with a light transmitting region that transmits light and a light shielding region that blocks some of the light, wherein a light collecting spot of light by the light collecting units and the light attenuation structure are separated from each other in a direction perpendicular to the light incident surface of the semiconductor substrate.