Photodetector and electronic device

Abstract

The present disclosure relates to a photodetector and an electronic device that are capable of suppressing cracks. This photodetector has a pixel array part in which a plurality of pixels are arranged in the row direction and the column direction on a semiconductor substrate. The pixel array part has an inter-pixel separation portion provided between the pixels. The inter-pixel separation portion has a first intersection portion and a second intersection portion in plan view, and a linear portion located between the first intersection portion and the second intersection portion. The first intersection portion and the second intersection portion have, in cross section, a trench structure that divides the semiconductor substrate from a first surface of the semiconductor substrate to a second surface on the opposite side thereof. The linear portion has a semiconductor region that is a part of the semiconductor substrate in cross section, and a trench structure. The present disclosure can be applied, for example, to an imaging device that generates and outputs an imaging signal corresponding to the amount of incident light.

Description

Photodetector and electronic equipment

[0001] The present disclosure relates to a photodetector and an electronic device, and more particularly to a photodetector and an electronic device that are capable of suppressing cracks.

[0002] Conventionally, there has been a solid-state imaging device in which a trench is formed at the boundary between pixels so as to penetrate the semiconductor substrate, thereby completely isolating the photoelectric conversion unit of each pixel, in order to suppress color mixing when pixels are miniaturized and to ensure a sufficient saturation charge amount Qs (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2018-148116

[0004] The boundaries between completely isolated pixels are filled with insulating films and metal materials, but there is concern that cracks may occur at the pixel boundaries due to warping that occurs during the manufacturing process and various stresses that are applied during the process.

[0005] The present disclosure has been made in view of such circumstances, and aims to make it possible to suppress cracks.

[0006] A photodetector according to a first aspect of the present disclosure includes a pixel array section in which a plurality of pixels are arranged in row and column directions on a semiconductor substrate, the pixel array section having inter-pixel separation sections between each pixel, the inter-pixel separation sections having, in a planar view, a first intersection and a second intersection and a straight section located between the first intersection and the second intersection, the first intersection and the second intersection having a trench structure in a cross-sectional view that separates the semiconductor substrate from a first surface of the semiconductor substrate to a second surface on the opposite side, and the straight section having a trench structure and a semiconductor region that is part of the semiconductor substrate in the cross-sectional view.

[0007] An electronic device according to a second aspect of the present disclosure comprises a photodetector device having a pixel array section in which a plurality of pixels are arranged in row and column directions on a semiconductor substrate, the pixel array section having inter-pixel separation sections provided between each pixel, the inter-pixel separation sections having, in a planar view, a first intersection and a second intersection and a straight section located between the first intersection and the second intersection, the first intersection and the second intersection having, in a cross-sectional view, a trench structure that separates the semiconductor substrate from a first surface of the semiconductor substrate to a second surface on the opposite side, and the straight section having, in the cross-sectional view, a semiconductor region that is part of the semiconductor substrate and a trench structure.

[0008] In first and second aspects of the present disclosure, a pixel array section is provided on a semiconductor substrate, in which a plurality of pixels are arranged in a row direction and a plurality of pixels are arranged in a column direction, and an inter-pixel separation section is provided between each pixel in the pixel array section. The inter-pixel separation section is provided with a first intersection and a second intersection in a plan view, and a linear section located between the first intersection and the second intersection, the first intersection and the second intersection having a trench structure separating the semiconductor substrate from a first surface of the semiconductor substrate to a second surface on the opposite side in a cross-sectional view, and the linear section is configured to have a trench structure with a semiconductor region that is a part of the semiconductor substrate in the cross-sectional view.

[0009] The photodetector and electronics may be stand-alone devices or may be modules that are incorporated into other devices.

[0010] FIG. 1 is a diagram illustrating a schematic configuration of a photodetector to which the technology of the present disclosure is applied; FIG. 2 is a diagram illustrating an equivalent circuit of a pixel; FIG. 3 is a cross-sectional view illustrating a first configuration example of a pixel; FIG. 4 is a plan view illustrating a first configuration example of a pixel; FIG. 5 is a diagram illustrating a method for manufacturing a pixel according to the first configuration example; FIG. 6 is a diagram illustrating a method for manufacturing a pixel according to the first configuration example; FIG. 7 is a diagram illustrating a method for manufacturing a pixel according to the first configuration example; FIG. 8 is a cross-sectional view illustrating a first modified example of a pixel according to the first configuration example; FIG. 9 is a plan view illustrating a third modified example of a pixel according to the first configuration example; FIG. 10 is a diagram illustrating an effect of an inter-pixel separator; FIG. 11 is a cross-sectional view illustrating a second modified example of a pixel according to the first configuration example; FIG. 12 is a cross-sectional view illustrating a third modified example of a pixel according to the third configuration example; FIG. 13 is a cross-sectional view illustrating a first modified example of a pixel according to the third configuration example; FIG. 14 is a cross-sectional view illustrating a second modified example of a pixel according to the third configuration example; FIG. 15 is a cross-sectional view illustrating a third modified example of a pixel according to the third configuration example; FIG. 10 is a cross-sectional view showing a fourth modified example of a pixel according to the third configuration example. FIG. 11 is a diagram illustrating a method for manufacturing a pixel according to the third configuration example. FIG. 12 is a diagram illustrating a method for manufacturing a pixel according to the third configuration example. FIG. 13 is a block diagram illustrating an example of the configuration of an electronic device. FIG. 14 is a diagram illustrating an example of use of an image sensor. FIG. 15 is a diagram illustrating an example of the schematic configuration of an endoscopic surgery system. FIG. 16 is a block diagram illustrating an example of the functional configuration of a camera head and a CCU. FIG. 17 is a block diagram illustrating an example of the schematic configuration of a vehicle control system. FIG. 18 is an explanatory diagram illustrating an example of the installation positions of an outside-vehicle information detection unit and an imaging unit.

[0011] Modes for carrying out the technology of the present disclosure (hereinafter referred to as embodiments) will be described below with reference to the accompanying drawings. The description will be given in the following order: 1. Schematic configuration example of a photodetector 2. Equivalent circuit of a pixel 3. First configuration example of a pixel 4. Method for manufacturing a pixel according to the first configuration example 5. Modification of the first configuration example 6. Function and effect of the inter-pixel isolation section of the present disclosure 7. Second configuration example of a pixel 8. Third configuration example of a pixel 9. Modification of the third configuration example 10. Method for manufacturing a pixel according to the third configuration example 11. Configuration example of an electronic device 12. Example of use of an image sensor 13. Example of application to an endoscopic surgery system 14. Example of application to a moving body

[0012] In this specification and drawings, identical or similar parts are denoted by identical or similar reference numerals, and redundant explanations are omitted as appropriate. The drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc. may differ from the actual ones. Furthermore, there may be parts in which the dimensional relationships and ratios differ between the drawings.

[0013] Furthermore, the definitions of directions such as up and down in the following description are merely for the convenience of explanation and do not limit the technical idea of ​​the present disclosure. For example, if an object is rotated 90 degrees and observed, up and down are converted to left and right and read, and if it is rotated 180 degrees and observed, up and down are read inverted.

[0014] The technology disclosed herein can be applied to a photodetector having a pixel array in which pixels are arranged two-dimensionally in a matrix, and which photoelectrically converts incident light to output a pixel signal corresponding to the amount of light. The light to be detected may be light in the visible light range including wavelengths such as R (Red), G (Green), and B (Blue), or light in the non-visible light range such as infrared light. Alternatively, light in both the visible and non-visible light ranges may be used. The photodetector can be used as an imaging device that generates and outputs an imaging signal corresponding to the amount of incident light, or as a light receiving device (ranging sensor) in a ranging system that receives light (reflected light) that is emitted as active light from an object and reflects infrared light off the object, thereby measuring the distance to the object using a direct ToF or indirect ToF method.

[0015] 1. Schematic Configuration Example of Photodetector FIG. 1 is a diagram showing a schematic configuration of a photodetector to which the technology of the present disclosure is applied.

[0016] 1 is configured to include a pixel array section 3 in which a plurality of pixels 2 are arranged in rows and columns on a semiconductor substrate 21 made of, for example, silicon (Si) as a semiconductor, and a peripheral circuit section surrounding the pixel array section 3. The peripheral circuit section includes a vertical drive circuit 4, a column signal processing circuit 5, a horizontal drive circuit 6, an output circuit 7, a control circuit 8, etc.

[0017] The pixel 2 includes a photodiode, which is a photoelectric conversion unit, and a plurality of pixel transistors, each of which is made up of, for example, a transfer transistor, a selection transistor, a reset transistor, and an amplification transistor, each of which is made up of a MOS transistor (MOS FET).

[0018] The pixels 2 may also have a shared pixel structure. This shared pixel structure is composed of multiple photodiodes, multiple transfer transistors, one shared floating diffusion, and one other pixel transistor each. That is, in the shared pixel structure, a photodiode and a transfer transistor are disposed in each pixel 2, and the other pixel transistors are shared by multiple pixels 2.

[0019] The control circuit 8 receives an input clock and data instructing the operation mode and the like, and outputs data such as internal information of the photodetector 1. That is, the control circuit 8 generates clock signals and control signals that serve as references for the operations of the vertical drive circuit 4, column signal processing circuit 5, horizontal drive circuit 6, etc., based on a vertical synchronization signal, a horizontal synchronization signal, and a master clock. The control circuit 8 then outputs the generated clock signals and control signals to the vertical drive circuit 4, column signal processing circuit 5, horizontal drive circuit 6, etc.

[0020] The vertical drive circuit 4 is configured by, for example, a shift register, selects a predetermined pixel drive wiring 10, supplies a pulse for driving the pixels 2 to the selected pixel drive wiring 10, and drives the pixels 2 row by row. That is, the vertical drive circuit 4 selects and scans each pixel 2 of the pixel array unit 3 row by row in the vertical direction, and supplies a signal based on a signal charge generated in the photoelectric conversion unit of each pixel 2 according to the amount of received light to the column signal processing circuit 5 through the vertical signal line 9.

[0021] The column signal processing circuits 5 are arranged for each column of pixels 2, and perform signal processing such as noise removal for each pixel column on signals output from one row of pixels 2. For example, the column signal processing circuits 5 perform signal processing such as CDS (Correlated Double Sampling) for removing fixed pattern noise specific to each pixel and AD conversion.

[0022] The horizontal drive circuit 6 is configured, for example, by a shift register, and sequentially outputs horizontal scanning pulses to select each of the column signal processing circuits 5 in turn, causing each of the column signal processing circuits 5 to output a pixel signal to the horizontal signal line 11.

[0023] The output circuit 7 processes and outputs signals sequentially supplied from each of the column signal processing circuits 5 through the horizontal signal line 11. The output circuit 7 may perform only buffering, or may perform black level adjustment, column variation correction, various digital signal processing, etc. The input / output terminal 13 exchanges signals with the outside.

[0024] The photodetector 1 configured as described above has a structure known as a column AD system, in which column signal processing circuits 5 that perform CDS processing and AD conversion processing are arranged for each column. The photodetector 1 generates a signal corresponding to the amount of light received by each pixel 2 in the pixel array section 3 and outputs the signal to the outside. The photodetector 1 can be used, for example, as a solid-state imaging device that detects the distribution of incident light amounts of infrared light or visible light and captures an image, or as a light receiving device in a distance measurement system that receives light (reflected light) that is irradiated as active light from an object and reflects it, using a direct ToF system or an indirect ToF system to measure the distance to the object.

[0025] 2. Equivalent Circuit of Pixel> FIG. 2 shows an equivalent circuit of the pixel 2.

[0026] The pixel 2 includes, for example, a photodiode PD as a photoelectric conversion unit, a transfer transistor TG electrically connected to the photodiode PD, and a floating diffusion FD electrically connected to the transfer transistor TG. The pixel 2 also includes a reset transistor RST, an amplification transistor AMP, and a selection transistor SEL. The transfer transistor TG, reset transistor RST, amplification transistor AMP, and selection transistor SEL are each configured, for example, by an n-type MOS transistor (MOS FET).

[0027] The photodiode PD photoelectrically converts incident light and generates an electric charge (signal charge) according to the amount of incident light received. The cathode of the photodiode PD is electrically connected to the source of the transfer transistor TG, and the anode is electrically connected to a reference potential line (e.g., ground).

[0028] The transfer transistor TG controls the transfer of charges generated in the photodiode PD. When the transfer transistor TG is turned on, it transfers the charges generated in the photodiode PD to the floating diffusion FD. The drain of the transfer transistor TG is electrically connected to the floating diffusion FD, and the gate is electrically connected to a pixel drive wiring. This pixel drive wiring is part of the pixel drive wiring 10 described in FIG. 1.

[0029] The floating diffusion FD is a charge storage unit that temporarily stores the charge transferred from the photodiode PD, and a charge-voltage converter that generates a voltage according to the amount of charge. The floating diffusion FD is electrically connected to the gate of the amplifier transistor AMP and the source of the reset transistor RST.

[0030] The reset transistor RST resets the potential of the floating diffusion FD to a predetermined potential. When the reset transistor RST is turned on by the pixel drive wiring supplied to its gate, it resets the potential of the floating diffusion FD to the potential of the power supply line VDD. This pixel drive wiring is part of the pixel drive wiring 10 described in FIG. 1. When the potential of the floating diffusion FD is reset, the reset transistor RST is also controlled to the on state at the same time.

[0031] The amplification transistor AMP generates a pixel signal having a voltage corresponding to the level of charge accumulated in the floating diffusion FD. The amplification transistor AMP is connected in series with the selection transistor SEL and connected to a vertical signal line 9 via the selection transistor SEL. The amplification transistor AMP forms a source follower together with a load circuit section in the column signal processing circuit 5 connected to the vertical signal line 9. When the selection transistor SEL is turned on, the amplification transistor AMP outputs the voltage of the floating diffusion FD to the column signal processing circuit 5 via the vertical signal line 9. The drain of the amplification transistor AMP is connected to a power supply line VDD, and the source of the amplification transistor AMP is connected to the drain of the selection transistor SEL.

[0032] The selection transistor SEL controls the output timing of the pixel signal. The source of the selection transistor SEL is connected to a vertical signal line 9, and the gate of the selection transistor SEL is connected to a pixel drive line. When the selection transistor SEL is turned on by the pixel drive line supplied to its gate, it outputs the pixel signal from the amplification transistor AMP to the vertical signal line 9. This pixel drive line is part of the pixel drive line 10 described in FIG. 1.

[0033] The selection transistor SEL may be provided between the power supply line VDD and the amplification transistor AMP. In this case, the drain of the reset transistor RST is electrically connected to the power supply line VDD and the drain of the selection transistor SEL. The source of the selection transistor SEL is electrically connected to the drain of the amplification transistor AMP. The source of the amplification transistor AMP (the output terminal of the pixel 2) is electrically connected to the vertical signal line 9, and the gate of the amplification transistor AMP is electrically connected to the source of the reset transistor RST.

[0034] The pixel 2 configured as above photoelectrically converts incident light under the control of the vertical drive circuit 4 and outputs a pixel signal according to the amount of received light to the column signal processing circuit 5 via the vertical signal line 9 .

[0035] 3. First Configuration Example of Pixel> A first configuration example of the pixel 2 of the photodetector 1 will be described with reference to FIGS. 3 and 4. FIG.

[0036] Fig. 3 is a cross-sectional view of a first configuration example of a pixel 2 of the photodetector 1, and Fig. 4 is a plan view of the first configuration example of the pixel 2. Fig. 3 shows a cross-sectional view taken along line X-X' and a cross-sectional view taken along line Y-Y' in Fig. 4, and Fig. 4 shows a plan view taken along line Z-Z' in Fig. 3. Line X-X' is a line passing through a corner of the pixel 2 having a rectangular pixel region, and line Y-Y' is a line crossing the center of the pixel region in the horizontal or vertical direction.

[0037] As shown in FIG. 3 , the pixel 2 includes a semiconductor substrate (silicon substrate) 21 using, for example, silicon (Si) as a semiconductor, and a wiring layer 22 formed on a first surface FA of the semiconductor substrate 21. The first surface FA of the semiconductor substrate 21 on which the wiring layer 22 is formed, which is the lower side in FIG. 3 , is the front surface of the semiconductor substrate 21, and the second surface SA of the semiconductor substrate 21, which is the upper side in FIG. 3 , is the back surface of the semiconductor substrate 21, which is the light receiving surface (light incident surface) onto which light is incident. Therefore, the photodetector 1 including the pixel 2 is a back-illuminated photodetector in which light is incident from the back surface side of the semiconductor substrate 21. Note that a logic substrate on which a logic circuit is formed is bonded to the lower side of the wiring layer 22, but is not shown in the figure.

[0038] On the second surface SA side, which is the light-receiving surface side of the semiconductor substrate 21, a fixed charge film 23, an insulating film 24, a color filter 25, an inter-pixel light-shielding film 26, and an on-chip lens (OCL) 27 are formed.

[0039] The semiconductor substrate 21 is made of, for example, silicon (Si) and is formed to have a thickness of, for example, 2 to 15 μm. In the semiconductor substrate 21, for example, a P-type (first conductivity type) semiconductor region 41 (hereinafter referred to as the P-type semiconductor region 41) is formed with an N-type (second conductivity type) semiconductor region 42 (hereinafter referred to as the N-type semiconductor region 42) for each pixel 2, thereby forming a photodiode PD for each pixel. The N-type semiconductor region 42 serves as a charge accumulation region for the photodiode PD. The P-type semiconductor regions 41 provided on both the front and back surfaces of the semiconductor substrate 21 also serve as hole charge accumulation regions for suppressing dark current.

[0040] Between each pixel 2 on the semiconductor substrate 21, an inter-pixel isolation portion 43 is formed, isolating the photodiodes PD of each pixel 2. The inter-pixel isolation portion 43 includes a fixed charge film 44 formed on the side surfaces, an insulating film 45, and an air gap 46 formed in the center inside the insulating film 45. A P-type semiconductor region 47 is formed between the inter-pixel isolation portion 43 and the photodiode PD in the planar direction (horizontal direction). The fixed charge film 44 is formed using a high dielectric constant material with a negative fixed charge to suppress the generation of dark current. The P-type semiconductor region 47 enhances electrical isolation between pixels. The impurity concentration of the P-type semiconductor region 47 is formed to be higher than that of the P-type semiconductor region 41, which is the substrate region, but may be the same as that of the P-type semiconductor region 41. The insulating film 45 can be made of, for example, SiO2 or a composite material mainly composed of SiO2 (SiON, SiOC, etc.). The fixed charge film 44 may be made of, for example, hafnium oxide (HfO2), zirconium dioxide (ZrO2), or tantalum oxide (Ta2O5).

[0041] At the linear portions of the inter-pixel isolation portions 43 corresponding to the sides of the rectangular pixel region, as shown in the Y-Y' cross-sectional view, shallow trench isolation (STI) 48 is formed on the first surface FA side of the semiconductor substrate 21, and a p-type semiconductor region 47 is formed on the second surface SA side. Meanwhile, at the intersections of the inter-pixel isolation portions 43 corresponding to the corners of the rectangular pixel region, as shown in the X-X' cross-sectional view, the STI 48 is formed on the first surface FA side of the semiconductor substrate 21, but the p-type semiconductor region 47 is not formed on the second surface SA side. On the second surface SA side of the intersections of the inter-pixel isolation portions 43, the insulating film 45 of the inter-pixel isolation portions 43 is connected to the insulating film 24 formed above the second surface SA. Furthermore, the fixed charge film 44 formed on the side surfaces of the inter-pixel isolation portions 43 is also connected to the fixed charge film 23 formed on the second surface SA. In the straight line portion of the inter-pixel isolation portion 43 shown in the cross-sectional view along line Y-Y', a fixed charge film 44 is formed on the side, top, and bottom surfaces of the trench between the STI 48 on the first surface FA side and the P-type semiconductor region 47 on the second surface SA side. In the straight line portion of the inter-pixel isolation portion 43, the P-type semiconductor region 47, which is part of the semiconductor substrate 21, is located between the insulating film 24 and fixed charge film 23 formed on the second surface SA and the insulating film 45 and fixed charge film 44 of the inter-pixel isolation portion 43 in the substrate.

[0042] In other words, the intersection of the inter-pixel isolation portion 43 has a trench structure that penetrates the semiconductor substrate 21 from the first surface FA to the second surface SA of the semiconductor substrate 21 to completely isolate it, and is filled with the fixed charge film 44, the insulating film 45, the air gap 46, and the STI 48, while the straight portion has a trench structure with the P-type semiconductor region 47 on the second surface SA side, which is a part of the semiconductor substrate 21 that does not penetrate the semiconductor substrate 21 and remains, and is filled with the fixed charge film 44, the insulating film 45, the air gap 46, and the STI 48. The trench structure may also be called a groove portion, an excavated portion, a hole, or the like.

[0043] As shown in the plan view of FIG. 4 , the inter-pixel isolation portions 43 are arranged in a grid pattern along the boundaries of the pixels 2 indicated by the dashed-dotted lines. The inter-pixel isolation portions 43 include multiple intersections 43A and linear portions 43B located between two adjacent intersections 43A, e.g., a first intersection 43A1 and a second intersection 43A2. At the intersections 43A, the semiconductor substrate 21 is separated across the entire thickness of the substrate by a trench structure, and a fixed charge film 44, an insulating film 45, and the like are embedded in the trench structure. Meanwhile, at the linear portions 43B, a P-type semiconductor region 47 connects portions of the semiconductor substrate 21, resulting in a structure in which the trench does not penetrate. All of the intersections 43A in the pixel array portion 3 may have a trench structure that completely separates the semiconductor substrate 21, with the fixed charge film 44, the insulating film 45, and the like embedded in the trench structure. Alternatively, only a plurality of intersections 43A at predetermined locations in the pixel array portion 3 may have such an isolation structure.

[0044] As shown in the cross-sectional view of FIG. 3 , the wiring layer 22 formed on the first surface FA of the semiconductor substrate 21 includes multiple layers of metal wiring 51 and insulating films (interlayer insulating films) 52 formed therebetween. The metal wiring 51 is formed of, for example, a metal film made of a metal material such as Al, Ag, Au, Cu, Pt, Mo, Cr, Ti, Ni, W, or Fe, or an alloy material containing these metals. The metal wiring 51 in each layer is connected to other metal wiring 51 in the upper and lower layers at predetermined locations by via plugs made of, for example, W or Cu. The insulating films 52 are formed of, for example, a SiO2 film, a low-k film (low-dielectric constant insulating film), or a SiOC film. The wiring layer 22 includes multiple pixel transistors Tr, such as a transfer transistor TG, which reads out charges stored in the photodiodes PD.

[0045] The fixed charge film 23 formed on the second surface SA, which is the back surface side of the semiconductor substrate 21, is a film having negative fixed charges, similar to the fixed charge film 44, and suppresses the generation of dark current. The fixed charge film 23 on the second surface SA and the fixed charge film 44 of the inter-pixel isolation portion 43 are formed simultaneously in the same process, as will be described later. The insulating film 24 formed on the fixed charge film 23 is also formed simultaneously in the same process as the insulating film 45 of the inter-pixel isolation portion 43.

[0046] The color filter 25 transmits light of a predetermined wavelength, such as R (red), G (green), or B (blue), from the light incident through the on-chip lens 27 and allows it to enter the photodiode PD. The color filter 25 is formed by spin-coating a photosensitive resin containing a coloring material such as a pigment or dye. The red, green, and blue colors are arranged in each pixel, for example, in a Bayer array, but other arrangement methods are also possible. For example, a color filter array may be an RGBW array in which W is added to R, G, and B. The W color filter is a color filter that transmits light of all R, G, and B colors (wavelengths) and is sometimes referred to as C (clear). Complementary color filters, such as yellow (Y), cyan (Cy), and magenta (Mg), may also be arranged.

[0047] The inter-pixel light-shielding film 26 is provided to prevent light from leaking into adjacent pixels 2. The inter-pixel light-shielding film 26 is made of a single-layer metal film such as titanium (Ti), titanium nitride (TiN), tungsten (W), aluminum (Al), or tungsten nitride (WN). Alternatively, the inter-pixel light-shielding film 26 may be made of a laminated film of these metals (e.g., a laminated film of titanium and tungsten, or a laminated film of titanium nitride and tungsten).

[0048] An on-chip lens 27 is formed on the upper side of the color filter 25 for each pixel 2. The on-chip lens 27 is made of a resin material such as a styrene-based resin, an acrylic-based resin, a styrene-acrylic copolymer resin, or a siloxane-based resin. The on-chip lens 27 condenses incident light, and the condensed light passes through the color filter 25 and is efficiently incident on the photodiode PD.

[0049] As described above, the pixel array section 3 of the photodetector 1 has inter-pixel isolation sections 43 at the boundaries of each pixel 2. The inter-pixel isolation sections 43 have a structure that completely isolates the semiconductor substrate 21 at intersections corresponding to corners of the pixel region, and a structure in which parts of the semiconductor substrate 21 are connected at linear sections by P-type semiconductor regions 47 near the second surface SA. This structure can suppress cracks compared to an inter-pixel isolation structure in which all pixel boundaries are completely isolated. The crack suppression effect of the inter-pixel isolation sections 43 will be described later with reference to FIG. 17 .

[0050] 4. Method for Manufacturing Pixel According to First Configuration Example A method for manufacturing the pixel 2 according to the first configuration example described above will be described with reference to FIGS.

[0051] First, as shown in FIG. 5 , with the first surface FA, which is the front surface of the semiconductor substrate 21, facing up, N-type impurities such as phosphorus (P) and arsenic (As) are ion-implanted into each pixel region of the semiconductor substrate 21, which is formed of a P-type semiconductor region 41, to form an N-type semiconductor region 42, thereby forming a photodiode PD for each pixel. Next, the semiconductor substrate 21 is excavated to a predetermined depth from the first surface FA side by dry etching, forming trenches 101 at the boundaries of the pixels 2. The trenches 101 are formed in a lattice pattern in plan view. As can be seen by comparing the depths of the trenches 101 in the X-X′ and Y-Y′ cross-sectional views, the trenches 101 are formed so that the intersections of the inter-pixel isolation regions 43 are deeper than the linear portions. For example, as shown in FIG. 6 , by making the opening width of the mask wider at the intersections than at the linear portions during dry etching, the trenches 101 at the intersections can be formed deeper than at the linear portions due to the microloading effect. An STI 48 is formed around the trench 101 on the first surface FA of the semiconductor substrate 21. The STI 48 may be formed after the trench 101 is formed, or may be formed before the trench 101 is formed.

[0052] Next, as shown in FIG. 7 , P-type impurities such as boron (B) and gallium (Ga) are ion-implanted into the side and bottom surfaces of the trench 101, forming a P-type semiconductor region 47 in a region at a predetermined depth from the side and bottom surfaces of the trench 101. The impurity concentration of the P-type semiconductor region 47 is, for example, higher than that of the P-type semiconductor region 41, which is the substrate region. After that, a buried material 111 is buried inside the trench 101, and an STI 48 is formed near the interface on the first surface FA side, blocking the first surface FA side of the trench 101. This results in the STI 48 being integrated with the STI 48 on both sides of the inter-pixel isolation portion 43 on the first surface FA side of the semiconductor substrate 21. In the plan views of line Z-Z′ in FIGS. 7 to 10 , the buried material 111 formed deeper than the STI 48 is also superimposed to show the arrangement of the buried material 111. The filling material 111 may be a single layer or a multilayer film of, for example, SiO2, SiN, polysilicon, or the like.

[0053] 8, pixel transistors Tr such as transfer transistors TG are formed on the first surface FA interface of the semiconductor substrate 21, and then a wiring layer 22 is formed, which is made up of multiple layers of metal wiring 51 and insulating films 52 therebetween. The wiring layer 22 is formed by sequentially stacking insulating films 52 such as silicon oxide films and metal wiring 51 made of aluminum, copper, or the like, and electrically connecting the metal wiring 51 of each layer with via plugs (through vias) or the like as needed.

[0054] Next, as shown in FIG. 9 , the entire semiconductor substrate 21 on which the wiring layer 22 is formed is turned upside down, and a logic board manufactured in a separate process is bonded to the wiring layer 22 by plasma bonding or the like. Then, the semiconductor substrate 21 is thinned to a desired thickness from the top surface (second surface SA) of the semiconductor substrate 21 using, for example, wet etching, dry etching, CMP, or the like. The thickness of the semiconductor substrate 21 varies depending on the target wavelength assumed for the incident light. For example, if the target wavelength is only wavelengths in the visible light region, the thickness of the semiconductor substrate 21 is preferably in the range of 2 to 6 μm, for example. Alternatively, if the target wavelength also includes wavelengths in the near-infrared region, the thickness of the semiconductor substrate 21 is preferably in the range of 3 to 15 μm, for example.

[0055] 10 , the second surface SA side of the semiconductor substrate 21 is further removed using, for example, wet etching, dry etching, CMP, etc. As a result, the thickness of the semiconductor substrate 21 becomes such that the filling material 111 protrudes at the intersections of the inter-pixel isolation portions 43 and the filling material 111 is not exposed at the linear portions.

[0056] 11 , the filling material 111 filled in the trenches 101 of the pixel isolation portions 43 is removed to form cavities 121. The filling material 111 in the trenches 101 can be removed using, for example, wet etching or isotropic dry etching. The cavities 121 communicate with the rear surface side of the semiconductor substrate 21 at the intersections of the pixel isolation portions 43, and are blocked by the P-type semiconductor regions 47 at the linear portions. In the plan view of line Z-Z′, the linear portions of the pixel isolation portions 43 are also shown superimposed with the cavities 121 formed deeper than the P-type semiconductor regions 47.

[0057] Next, as shown in FIG. 12 , a fixed charge film 23 on the upper surface of the second surface SA of the semiconductor substrate 21 and a fixed charge film 44 on the side and bottom surfaces of the cavity 121 are simultaneously formed. Subsequently, an insulating film 24 on the upper surface of the fixed charge film 44 on the second surface SA of the semiconductor substrate 21 and an insulating film 45 on the inside of the fixed charge film 44 in the cavity 121 are simultaneously formed. When the insulating film 24 is formed to a predetermined thickness, as shown in FIG. 12 , a region in the cavity 121 where the insulating film 24 is not formed remains, forming an air gap 46. The insulating film 24 may be embedded entirely inside the fixed charge film 44 in the cavity 121, in which case the air gap 46 is not formed. The fixed charge films 23, 44 and the insulating films 24, 45 can be formed by, for example, CVD, sputtering, atomic layer deposition (ALD), or the like. For the linear portion of the inter-pixel isolation portion 43 whose second surface SA side is blocked by the P-type semiconductor region 47, a fixed charge film 44 is formed on the side and bottom of the cavity 121 as well as on the top surface. Examples of materials that can be used for the fixed charge film 44 include hafnium oxide (HfO2), aluminum oxide (Al2O3), zirconium dioxide (ZrO2), and tantalum oxide (Ta2O5). Examples of materials that can be used for the insulating film 45 include SiO2 and composite materials (SiON, SiOC, etc.) that contain SiO2 as a main component.

[0058] 13, an inter-pixel light-shielding film 26 and a color filter 25 are formed on the upper surface of the insulating film 24 above the second surface SA of the semiconductor substrate 21, and then an on-chip lens 27 is formed for each pixel 2, thereby completing the structure of the pixel 2 shown in FIG. 3. The inter-pixel light-shielding film 26 is formed simultaneously with the light-shielding film of the OPB pixels formed outside the effective pixel area. The OPB pixels are pixels that detect a black level reference signal, and the entire pixel area on the second surface SA side of the semiconductor substrate 21 is covered with a light-shielding film.

[0059] The pixel 2 according to the first configuration example shown in FIG. 3 can be manufactured by the method described above.

[0060] 5. Modifications of the First Configuration Example A description will be given of modifications of the pixel 2 according to the first configuration example described above. Hereinafter, the structure of the pixel 2 described with reference to FIG. 3 will be referred to as the basic structure.

[0061] 14 is a cross-sectional view showing a first modified example of pixel 2. The positions on the plan view of the cross-sectional view along line XX' and the cross-sectional view along line YY' in Fig. 14 are the intersections and straight line portions of inter-pixel separator 43 corresponding to lines XX' and YY' in Fig. 4.

[0062] In the pixel 2 according to the first modification shown in FIG. 14 , a reflection suppression portion 211 that suppresses reflection of incident light is further formed on the second surface SA of the semiconductor substrate 21. The pixel 2 according to the first modification has the same basic structure as that shown in FIG. 3 except for the inclusion of the reflection suppression portion 211. The reflection suppression portion 211 is configured as a concave-convex structure in which concaves and convexes are repeatedly arranged at a predetermined pitch on the second surface SA of the semiconductor substrate 21. A fixed charge film 23 formed on the second surface SA of the semiconductor substrate 21 is embedded in the concave portions, which are minute trenches, of the reflection suppression portion 211. The convex portions of the concave-convex structure are formed of the P-type semiconductor region 41 above the photodiode PD, and the linear portions of the inter-pixel separation portion 43 are formed of the P-type semiconductor region 47. The pitch of the convex portions and concave portions is equal to or less than the wavelength of light passing through the fixed charge film 23. The shapes of the convex portions and concave portions of the concave-convex structure may be rectangular pillars, cylindrical, quadrangular pyramids, or the like.

[0063] The pixel 2 according to the first modified example configured as described above can further suppress reflection of incident light by further including the reflection suppression portion 211. The reflection suppression portion 211 is also formed on the P-type semiconductor region 47 formed in the linear portion of the inter-pixel isolation portion 43, and the area of ​​the P-type semiconductor region 47, which is part of the semiconductor substrate 21, is reduced, thereby improving the electrical isolation characteristics between pixels. Note that the reflection suppression portion 211 only needs to be formed on at least the light incident surface on the photodiode PD, and does not necessarily have to be formed on the intersections and linear portions of the inter-pixel isolation portion 43.

[0064] 15 is a cross-sectional view showing a second modified example of pixel 2. The positions on the plan view of the cross-sectional view along line XX' and the cross-sectional view along line YY' in Fig. 15 are the intersections and straight line portions of inter-pixel separator 43, which correspond to lines XX' and YY' in Fig. 4.

[0065] In a pixel 2 according to a second modification shown in FIG. 15 , the insulating films 24 and 45 of the basic structure shown in FIG. 3 are replaced with transparent electrodes 221 and 222. The inter-pixel isolation portion 43 includes a fixed charge film 44 formed on the side surface or the like, a transparent electrode 222, and an air gap 46. Near the second surface SA at the intersection of the inter-pixel isolation portion 43, the transparent electrode 222 of the inter-pixel isolation portion 43 is connected to the transparent electrode 221 formed above the second surface SA. A negative voltage (negative bias), for example, is applied to the transparent electrode 221 at the outer periphery of the pixel array portion 3. The transparent electrodes 221 and 222 are made of a transparent conductive material such as indium tin oxide (ITO), zinc oxide, or indium zinc oxide.

[0066] According to the pixel 2 of the second modified example configured as described above, the dark current suppression effect can be enhanced by providing transparent electrodes 221, 222 to which a negative bias is applied so as to be in contact with the fixed charge film 23 on the second surface SA of the semiconductor substrate 21 and the fixed charge film 44 of the inter-pixel separation portion 43.

[0067] 16 is a plan view illustrating a third modification of the pixel 2. In order to make the drawing easier to see, the fixed charge film 44 is omitted from the drawing in a simplified manner.

[0068] If one on-chip lens 27 is arranged as one pixel, the basic structure shown in Fig. 3 has one photodiode PD formed in one pixel and one transfer transistor TG transfers the signal charge generated in the photodiode PD, as shown in A of Fig. 16. The intersection 43A of the inter-pixel isolation portion 43 is a corner of the approximately rectangular pixel region in plan view, and is formed at the position of the corner of the photodiode PD.

[0069] On the other hand, as shown in FIG. 16B, there is a pixel structure in which the photoelectric conversion region is divided in half to place two photodiodes PD in one pixel, and two transfer transistors TG are arranged within one pixel so that the signal charges of the two photodiodes PD can be read out individually. An overflow path may be provided in the P-type semiconductor region 41 between the two photodiodes PD. With an overflow path, the amount of signal charge accumulates in each photodiode PD up to the height of the potential barrier of the overflow path. Once the potential barrier height is exceeded, the signal charge flows from one of the two photodiodes PD to the other via the overflow path. When the signal charges of the two photodiodes PD in one pixel are read out individually, it is possible to detect a phase difference. When the signal charges of the two photodiodes PD in one pixel are read out simultaneously, a signal similar to the signal of one photodiode PD in the pixel shown in FIG. 16A can be read out.

[0070] FIG. 16B shows a plan view of a third modified example of the pixel 2, in which an inter-pixel isolation portion 43 is applied to a pixel 2 in which two photodiodes PD and two transfer transistors TG are arranged in one pixel.

[0071] When two photodiodes PD are arranged in one pixel, intersections 43A of the inter-pixel isolation portions 43 are formed at the positions of the corners of the rectangular pixel region and the corners of the photodiodes PD in plan view. In the center of the pixel between the two photodiodes PD, which is also the position where an overflow path is formed, a P-type semiconductor region 41 is formed, and the inter-pixel isolation portion 43 is not formed.

[0072] According to the pixel 2 of the third modified example configured as described above, even in a pixel structure in which two photodiodes PD and two transfer transistors TG are arranged in one pixel, cracks can be suppressed by providing an inter-pixel separation portion 43.

[0073] Any two or more of the structures of the first to third modified examples described above may be appropriately combined and employed in the pixel 2. For example, the first modified example and the second modified example may be combined to form a structure having the anti-reflection portion 211 with a concave-convex structure and the transparent electrodes 221 and 222.

[0074] 6. Effects of Inter-Pixel Isolation Portion of Present Disclosure> With reference to FIG. 17 , the effects of the inter-pixel isolation portion 43 of pixel 2 will be described in comparison with other inter-pixel isolation structures.

[0075] 17A to 17C show isolation structures in which at least a portion of the intersections 43A or linear portions 43B of the inter-pixel isolation portion 43 is penetrated, and are diagrams comparing the crack suppression effect depending on the location of the penetration portion. In Figures 17A to 17C, the hatched areas indicate the locations of the penetration portions that penetrate the semiconductor substrate 21. The structure of the inter-pixel isolation portion 43 of pixel 2 is the structure shown in Figure 17B, in which only the intersections 43A are penetrated.

[0076] 17A shows an inter-pixel isolation structure in which the linear portion 43B of the inter-pixel isolation portion 43 is formed so as to penetrate the semiconductor substrate 21. In such an inter-pixel isolation structure, there are many penetrating portions, and the strength is weak. Furthermore, although it is thought that cracks tend to propagate along the surface orientation of the silicon substrate, it is thought that when a crack occurs in the inter-pixel isolation portion 43, the crack is less likely to propagate in the inter-pixel isolation structure of FIG. 17A.

[0077] 17B shows an inter-pixel isolation structure in which the inter-pixel isolation portion 43 has an intersection 43A formed so as to penetrate the semiconductor substrate 21. In such an inter-pixel isolation structure, the number of penetrating portions is small and the strength is high. Furthermore, when a crack occurs in the inter-pixel isolation portion 43, the crack is thought to be less likely to propagate in the inter-pixel isolation structure of FIG. 17B.

[0078] 17C shows an inter-pixel isolation structure in which a part of the linear portion 43B of the inter-pixel isolation portion 43 is formed to penetrate the semiconductor substrate 21. In such an inter-pixel isolation structure, the number of penetrating portions is small and the strength is high. Furthermore, when a crack occurs in the inter-pixel isolation portion 43, the crack is thought to be less likely to propagate in the inter-pixel isolation structure of FIG. 17C.

[0079] From the above, it is believed that all of the inter-pixel isolation structures of A to C in Figure 17 are structures that make it difficult for cracks to propagate. From the viewpoint of strength, the inter-pixel isolation structures of B and C in Figure 17 are more preferable than A in Figure 17. Furthermore, in the case of the inter-pixel isolation structures of B and C in Figure 17, if a crack were to occur, the inter-pixel isolation structure of C in Figure 17 could affect four pixels, but the inter-pixel isolation structure of B in Figure 17 would only affect two pixels.

[0080] As described above, the inter-pixel isolation portion 43 of the pixel 2 has a structure that is strong, can suppress cracks, and is less susceptible to crack propagation.

[0081] 7. Second Configuration Example of Pixel Next, a second configuration example of the pixel 2 of the photodetector 1 will be described with reference to FIGS. 18 and 19. FIG.

[0082] Fig. 18 is a cross-sectional view of a pixel 2 according to a second configuration example of the photodetector 1, and Fig. 19 is a plan view of the pixel 2 according to the second configuration example. Fig. 18 shows a cross-sectional view taken along line Y-Y' in Fig. 19, and Fig. 19 shows a plan view taken along line Z-Z' in Fig. 18.

[0083] 18 and 19, the same reference numerals are used to designate parts corresponding to those in the first configuration example described above, and duplicated explanations will be omitted where appropriate.

[0084] The pixel 2 according to the first configuration example described above has a structure in which the on-chip lenses 27 are arranged in pixel units. In contrast, in the pixel 2 according to the second configuration example, one on-chip lens 27 is arranged for four 2x2 pixels. The color filters 25 are arranged in the same color in units of four pixels that share the on-chip lens 27. Hereinafter, the four 2x2 pixels that share the on-chip lens 27 and in which color filters 25 of the same color are arranged will also be referred to as a sharing unit. The color filters 25 are arranged in a Bayer array in sharing units of, for example, R (red), G (green), and B (blue). FIG. 18 shows a cross-sectional view centered on two adjacent pixels in which one on-chip lens 27 and color filters 25 of the same color (G) are arranged.

[0085] The pixel 2 according to the second configuration example differs from the first configuration example in the configuration of the inter-pixel isolation portion 43. The inter-pixel isolation portion 43 according to the first configuration example includes a fixed charge film 44 formed on the side surface or the like, an insulating film 45, and an air gap 46 formed in the center inside the insulating film 45. In contrast, in the second configuration example, the inter-pixel isolation portion 43 that forms the boundary of the sharing unit (hereinafter referred to as the sharing unit boundary) includes a fixed charge film 44 formed on the side surface or the like, a high-refractive index film 401, an insulating film 45, and an air gap 46 formed in the center inside the insulating film 45, as shown in FIGS. 18 and 19 . Compared to the inter-pixel isolation portion 43 according to the first configuration example, a high-refractive index film 401 is newly added between the fixed charge film 44 and the insulating film 45 in the inter-pixel isolation portion 43 at the sharing unit boundary. On the other hand, the inter-pixel separating portion 43 inside the sharing unit (hereinafter referred to as the inside of the sharing unit) is composed only of the fixed charge film 44 and the high refractive index film 401 inside it.

[0086] 3 is omitted, but also in the second configuration example, at intersections 43A corresponding to corners of the pixel regions, the inter-pixel isolation portions 43 have a structure that completely isolates the semiconductor substrate 21, and on the second surface SA side, the insulating film 45 of the inter-pixel isolation portion 43 is connected to the insulating film 24 formed above the second surface SA. In addition, the fixed charge film 44 formed on the side surface of the inter-pixel isolation portion 43 is also connected to the fixed charge film 23 formed on the second surface SA.

[0087] The inter-pixel separation portion 43 at the boundary of the sharing unit has the color filters 25 of the pixels 2 on both sides of the inter-pixel separation portion 43 being different colors, and can also be said to be an inter-pixel separation portion 43 between different color filters. On the other hand, the inter-pixel separation portion 43 inside the sharing unit has the color filters 25 of the pixels 2 on both sides of the inter-pixel separation portion 43 being the same color, and can also be said to be an inter-pixel separation portion 43 between same color filters.

[0088] 18 , the inter-pixel isolation portion 43 inside the sharing unit and the inter-pixel isolation portion 43 serving as the sharing unit boundary are common in that they do not penetrate the semiconductor substrate 21, but rather a portion of the second surface SA side of the semiconductor substrate 21 remains, and a P-type semiconductor region 47 is formed therein. On the other hand, the inter-pixel isolation portion 43 inside the sharing unit and the inter-pixel isolation portion 43 serving as the sharing unit boundary have different trench widths and depths. Specifically, the trench depth from the first surface FA side of the semiconductor substrate 21 is shorter for the inter-pixel isolation portion 43 inside the sharing unit than for the inter-pixel isolation portion 43 serving as the sharing unit boundary, and the trench width for the inter-pixel isolation portion 43 inside the sharing unit is also narrower than for the inter-pixel isolation portion 43 serving as the sharing unit boundary. In other words, when processing the trench for the inter-pixel isolation portion 43, the width of the trench for the inter-pixel isolation portion 43 within the sharing unit is narrower than the width of the trench for the inter-pixel isolation portion 43 at the sharing unit boundary, so that the depth of the trench for the inter-pixel isolation portion 43 within the sharing unit is shallower than the inter-pixel isolation portion 43 at the sharing unit boundary. Furthermore, in the process of embedding the high-refractive index film 401 inside the trench, there are no gaps in the inter-pixel isolation portion 43 within the sharing unit, where the trench is narrow, so there is no room for the insulating film 45 or the air gap 46 to be formed. On the other hand, in the inter-pixel isolation portion 43 at the sharing unit boundary, where the trench is wide, gaps remain even after the high-refractive index film 401 is embedded, so the insulating film 45 and the air gap 46 are formed inside the high-refractive index film 401. As a result, the composition of the material embedded in the inter-pixel isolation portion 43 differs between the inter-pixel isolation portion 43 at the sharing unit boundary and the inter-pixel isolation portion 43 within the sharing unit.

[0089] The high-refractive-index film 401 is a film made of a material whose refractive index is lower than that of silicon (Si), the material of the semiconductor substrate 21, but higher than that of the inner insulating film 45 and air gap 46. The refractive index of silicon is approximately 3.8, the refractive index of the insulating film 45 material, e.g., SiO2, is approximately 1.4, and the refractive index of the air gap 46 is approximately 1.0. Therefore, the high-refractive-index film 401 can be made of a material with a refractive index in the range of 1.5 to 3.0, such as titanium oxide (TiO2), zirconium oxide (ZrO2), or tantalum oxide (Ta2O5). Alternatively, silicon nitride can be used. For example, the refractive index of titanium oxide (TiO2) is approximately 2.35. The refractive index of zirconium oxide (ZrO2) is approximately 2.05, the refractive index of tantalum oxide (Ta2O5) is approximately 2.1, and the refractive index of silicon nitride is approximately 2.0.

[0090] In the pixel 2 according to the second configuration example described above, similarly to the first configuration example described above, the inter-pixel isolation portion 43 has a structure in which the semiconductor substrate 21 is completely isolated at the intersections 43A corresponding to the corners of the pixel region, and in which a part of the semiconductor substrate 21 is connected at the linear portions 43B by the P-type semiconductor regions 47 near the second surface SA. This makes it possible to suppress cracks compared to a structure in which all pixel boundary portions are completely isolated from each other.

[0091] Moreover, the pixel 2 according to the second configuration example has a shared structure in which the on-chip lens 27 is shared by a plurality of pixels, and the inter-pixel isolation portion 43 at the boundary of the sharing unit includes a fixed charge film 44, a high-refractive index film 401 (first insulating material) and an insulating film 45 (second insulating material) having different refractive indices, and an air gap 46, while the inter-pixel isolation portion 43 inside the sharing unit includes the fixed charge film 44, the high-refractive index film 401 having the higher refractive index among the high-refractive index films 401 and the insulating film 45, but does not include the insulating film 45 having the lower refractive index and the air gap 46. As a result, the inter-pixel isolation portion 43 inside the sharing unit suppresses scattering of light incident into the pixel, and the inter-pixel isolation portion 43 at the boundary of the sharing unit totally reflects the light incident into the pixel, thereby having the effect of keeping the incident light within the photodiode PD.

[0092] 8. Third Configuration Example of Pixel Fig. 20 is a cross-sectional view of a third configuration example of the pixel 2 of the photodetector 1. Fig. 20 shows a cross-sectional view corresponding to the X-X' line and a cross-sectional view corresponding to the Y-Y' line in Fig. 4. The X-X' line is a line passing through a corner of the pixel 2 having a rectangular pixel region, and the Y-Y' line is a line crossing the center part of the pixel region in the horizontal or vertical direction.

[0093] In FIG. 20, the same reference numerals are used to designate parts corresponding to those in the first configuration example described above, and redundant explanations will be omitted where appropriate.

[0094] In the third configuration example, the linear portion 43B of the inter-pixel isolation portion 43 shown in the Y-Y' cross-sectional view includes a first trench structure 421 dug from the first surface FA side of the semiconductor substrate 21 and a second trench structure 422 dug from the second surface SA side. A portion of the semiconductor substrate 21 remains between the first trench structure 421 and the second trench structure 422, creating a non-isolated region. The trench structures of the first trench structure 421 and the second trench structure 422 are groove structures dug to a predetermined depth from the interface of the semiconductor substrate 21. The first trench structure 421 extends from the first surface FA to a predetermined depth, and the second trench structure 422 extends from the second surface SA to a predetermined depth. The non-isolated region of the semiconductor substrate 21 is a P-type semiconductor region 47. Similar to the first configuration example, a fixed charge film 44, an insulating film 45, an air gap 46, and an STI 48 are buried in the first trench structure 421. A fixed charge film 44, an insulating film 45, and an air gap 46 are buried in the second trench structure 422. The insulating film 45 in the second trench structure 422 is connected to the insulating film 24 formed above the second surface SA. In addition, the fixed charge film 44 formed on the side surface in the second trench structure 422 is connected to the fixed charge film 23 formed on the second surface SA.

[0095] The structure of the intersection 43A of the inter-pixel isolation portion 43 shown in the cross section along line XX' is the same as that of the first configuration example described above, and therefore a description thereof will be omitted.

[0096] In the third configuration example having the above configuration, the pixel array section 3 of the photodetector 1 has an inter-pixel isolation section 43 at the boundary between each pixel 2. The inter-pixel isolation section 43 has, in the linear portion 43B, a first trench structure 421 dug from the first surface FA side of the semiconductor substrate 21 and a second trench structure 422 dug from the second surface SA side, with a fixed charge film 44, an insulating film 45, and an air gap 46 embedded therein. In addition to the first trench structure 421 similar to that of the first configuration example described above, the second trench structure 422 is formed from the second surface SA side, and a structure in which the fixed charge film 44, the insulating film 45, and the air gap 46 are embedded is added. This reduces the non-isolated region of the semiconductor substrate 21 in the linear portion 43B compared to the first configuration example. This reduces the amount of light incident from adjacent pixels through the non-isolated region of the semiconductor substrate 21, thereby enhancing color mixing suppression compared to the first configuration example. Therefore, according to the third configuration example, cracks can be suppressed in the same way as in the first configuration example, and color mixing can be suppressed more than in the first configuration example.

[0097] 9. Modification of the Third Configuration Example A modification of the pixel 2 according to the third configuration example described above will be described. Portions corresponding to those in the basic structure of the third configuration example described in FIG. 20 are denoted by the same reference numerals, and duplicated descriptions will be omitted as appropriate.

[0098] (First Modification) Figure 21 is a cross-sectional view showing a first modification of pixel 2 according to the third configuration example. In Figure 21, the cross-sectional view along line X-X' is a cross-sectional view of intersection 43A of inter-pixel separator 43 corresponding to line X-X' in Figure 4, and the cross-sectional view along line Y-Y' is a cross-sectional view of linear portion 43B of inter-pixel separator 43 corresponding to line Y-Y' in Figure 4. The cross-sectional view along line X-X' is similar to the basic structure of the third configuration example shown in Figure 20 and the first configuration example shown in Figure 3.

[0099] In the first modified example of FIG. 21 , the internal configuration of the second trench structure 422 excavated from the second surface SA side in the cross-sectional view along line Y-Y′ differs from the basic structure of the third configuration example shown in FIG. 20 . Specifically, the basic structure of the third configuration example shown in FIG. 20 is configured such that the fixed charge film 44, the insulating film 45, and the air gap 46 are embedded inside the second trench structure 422. In contrast, the first modified example of FIG. 21 is configured such that the fixed charge film 44 and the air gap 46 are embedded inside the second trench structure 422. In other words, in the first modified example of FIG. 21 , the embedding of the insulating film 45 inside the second trench structure 422 is omitted. In this way, the embedding of the insulating film 45 inside the second trench structure 422 may be omitted. Conversely, the embedding of the air gap 46 may be omitted, and the fixed charge film 44 and the insulating film 45 may be embedded inside the second trench structure 422.

[0100] (Second Modification) Figure 22 is a cross-sectional view showing a second modification of pixel 2 according to the third configuration example. In Figure 22, the cross-sectional view along line X-X' is a cross-sectional view of intersection 43A of inter-pixel separator 43 corresponding to line X-X' in Figure 4, and the cross-sectional view along line Y-Y' is a cross-sectional view of linear portion 43B of inter-pixel separator 43 corresponding to line Y-Y' in Figure 4. The cross-sectional view along line X-X' is similar to the basic structure of the third configuration example shown in Figure 20 and the first configuration example shown in Figure 3.

[0101] In the second modified example of FIG. 22 , the internal configuration of the second trench structure 422 dug from the second surface SA side in the cross-sectional view along line Y-Y′ differs from the basic structure of the third configuration example shown in FIG. 20 . Specifically, in the second modified example, a filling material 431 different from the material filled in the first trench structure 421 is filled inside the second trench structure 422. The filling material 431 can be, for example, any of the materials exemplified as the material for the high-refractive-index film 401 in the second configuration example described above. For example, the filling material 431 may be an insulating material such as titanium oxide (TiO ), zirconium oxide (ZrO ), or tantalum oxide (Ta O ), or alternatively, silicon nitride. Note that, as in the first modified example shown in FIG. 21 , a fixed charge film 44 may be formed on the bottom and side surfaces of the second trench structure 422, and the filling material 431 may be provided inside the fixed charge film 44.

[0102] (Third Modification) Figure 23 is a cross-sectional view showing a third modification of pixel 2 according to the third configuration example. In Figure 23, the cross-sectional view along line X-X' is a cross-sectional view of intersection 43A of inter-pixel separator 43 corresponding to line X-X' in Figure 4, and the cross-sectional view along line Y-Y' is a cross-sectional view of linear portion 43B of inter-pixel separator 43 corresponding to line Y-Y' in Figure 4. The cross-sectional view along line X-X' is similar to the basic structure of the third configuration example shown in Figure 20 and the first configuration example shown in Figure 3.

[0103] In the third modification shown in FIG. 23 , in the cross-sectional view along line Y-Y′, the second trench structure 422 dug from the second surface SA side is replaced with a second trench structure 422A. The second trench structure 422A has a wider width in the planar direction than the first trench structure 421. The second trench structure 422A includes a microtrenches 422B, which are minute trench structures formed near the trench sidewalls. The microtrenches 422B make the depth of the second trench structure 422A near the trench sidewalls deeper than the top surface of the first trench structure 421. This further reduces the non-isolation region of the semiconductor substrate 21. The microtrenches 422B provide an overlapping region between the first trench structure 421 and the second trench structure 422A in the depth direction, which is perpendicular to the second surface SA of the semiconductor substrate 21, thereby reducing the amount of light incident from adjacent pixels through the non-isolation region of the semiconductor substrate 21. In the example of FIG. 23 , the materials embedded inside the second trench structure 422A are a fixed charge film 44, an insulating film 45, and an air gap 46, and have the same configuration as the materials embedded inside the first trench structure 421. However, as in the second configuration example shown in FIG. 22 , the material embedded inside the second trench structure 422A may be a material different from the material embedded inside the first trench structure 421.

[0104] (Fourth Modification) Figure 24 is a cross-sectional view showing a fourth modification of pixel 2 according to the third configuration example. In Figure 24, the cross-sectional view along line X-X' is a cross-sectional view of intersection 43A of inter-pixel separator 43 corresponding to line X-X' in Figure 4, and the cross-sectional view along line Y-Y' is a cross-sectional view of linear portion 43B of inter-pixel separator 43 corresponding to line Y-Y' in Figure 4. The cross-sectional view along line X-X' is similar to the basic structure of the third configuration example shown in Figure 20 and the first configuration example shown in Figure 3.

[0105] In the fourth modification example of FIG. 24 , in the cross-sectional view along line Y-Y′, the second trench structure 422 dug from the second surface SA side is replaced with two second trench structures 422C. In the cross-sectional view, the first trench structure 421 is disposed between the two second trench structures 422C, and the two second trench structures 422C are provided at positions outside the first trench structure 421. Each of the two second trench structures 422C has a narrower width in the planar direction than the first trench structure 421, and is dug from the second surface SA side to a depth deeper than the top surface of the first trench structure 421. By providing a region where the first trench structure 421 and the second trench structure 422C overlap in the depth direction, which is the direction perpendicular to the second surface SA of the semiconductor substrate 21, it is possible to reduce the amount of light incident from adjacent pixels through the non-isolation region of the semiconductor substrate 21. In the example of FIG. 24, an insulating film 45 is buried inside the two second trench structures 422C, but as in the second configuration example shown in FIG. 22, a material different from the material buried in the first trench structure 421 may be buried therein.

[0106] In the first to fourth modified examples of the third configuration example described above, cracks can be suppressed in the same way as in the first configuration example, and color mixing can be suppressed more effectively than in the first configuration example.

[0107] 25 to 27, a method for manufacturing the pixel 2 according to the third configuration example described in Fig. 20 will be described. In Fig. 25 to 27, differences from the method for manufacturing the pixel 2 according to the first configuration example described in Fig. 5 to Fig. 13 will be described.

[0108] 5 to 9 for pixel 2 according to the first configuration example are also applicable to the third configuration example. In the processes described with reference to Fig. 5 to 9, trench 101 formed by digging a predetermined depth into semiconductor substrate 21 from the first surface FA side by dry etching corresponds to first trench structure 421 in the third configuration example.

[0109] In the process described in FIG. 9, the entire semiconductor substrate 21 on which the wiring layer 22 is formed is turned upside down and bonded to a logic substrate manufactured in a separate process, thereby thinning the semiconductor substrate 21 to the desired thickness.

[0110] 9, as shown in the cross-sectional view of line Y-Y' in Fig. 25, the semiconductor substrate 21 is excavated by dry etching from the second surface SA side in a region that will become the linear portion 43B of the inter-pixel isolation portion 43, to form a second trench structure 422, and a filling material 441 is filled inside the second trench structure 422. The filling material 441 is the same material as the filling material 111 filled inside the trench 101 (first trench structure 421).

[0111] 26 , the second surface SA side of the semiconductor substrate 21 is further removed using, for example, wet etching, dry etching, CMP, etc. As a result, the thickness of the semiconductor substrate 21 is such that the filling material 111 protrudes from the intersection 43A in the X-X′ cross section, and the filling material 441 protrudes from the linear portion 43B in the Y-Y′ cross section.

[0112] Next, as shown in the X-X' cross-sectional view of FIG. 27 , the filling material 111 embedded in the trench 101 of the pixel isolation portion 43 is removed, forming a cavity 121. This cavity 121 corresponds to the first trench structure 421 in the third configuration example. Furthermore, as shown in the Y-Y' cross-sectional view of FIG. 27 , the filling material 441 embedded in the second trench structure 422 of the pixel isolation portion 43 is also removed simultaneously with the filling material 111. The filling materials 111 and 442 can be removed using, for example, wet etching or isotropic dry etching.

[0113] 27 is the same as the process described with reference to FIG. 12 in the manufacturing method of the pixel 2 according to the first configuration example. Specifically, a fixed charge film 44, an insulating film 45, and an air gap 46 are formed in the first trench structure 421 (cavity 121) and the second trench structure 422, and a fixed charge film 23 and an insulating film 24 are also formed on the second surface SA of the semiconductor substrate 21. Subsequently, as described with reference to FIG. 13, an inter-pixel light-shielding film 26, a color filter 25, and an on-chip lens 27 are formed on the upper surface of the insulating film 24 above the second surface SA of the semiconductor substrate 21, thereby completing the pixel 2 according to the third configuration example shown in FIG. 20.

[0114] The pixel 2 according to the third configuration example shown in FIG. 20 can be manufactured by the method described above.

[0115] 11. Configuration Examples of Electronic Devices The above-described light detection device 1 can be applied to various electronic devices, such as imaging systems such as digital still cameras and digital video cameras, mobile phones with imaging functions, or other devices with imaging functions.

[0116] FIG. 28 is a block diagram showing an example of the configuration of an electronic device.

[0117] 28 , electronic device 301 includes an optical system 302, a photodetector 303, a DSP (Digital Signal Processor) 304, a display device 305, an operation system 306, a memory 307, a recording device 308, and a power supply system 309. DSP 304, display device 305, operation system 306, memory 307, recording device 308, and power supply system 309 are interconnected via a bus 310. Electronic device 301 is, for example, an imaging device capable of capturing still images and moving images.

[0118] The optical system 302 is configured to have one or more lenses, and guides image light (incident light) from a subject to the photodetector 303 , forming an image on the light-receiving surface (sensor portion) of the photodetector 303 .

[0119] The photodetector 303 has the same configuration as the photodetector 1 described above. Electrons are accumulated as signal charges in the photodetector 303 for a certain period of time in accordance with an image formed on the light-receiving surface via the optical system 302. A signal corresponding to the electrons accumulated in the photodetector 303 is then supplied to the DSP 304.

[0120] The DSP 304 performs various signal processing on the signal from the photodetector 303 to generate an image, and temporarily stores the image data in a memory 307. The image data stored in the memory 307 is recorded in a recording device 308 or supplied to a display device 305 to display the image. In addition, an operation system 306 accepts various operations by a user and supplies operation signals to each block of the electronic device 301, and a power supply system 309 supplies the power necessary to drive each block of the electronic device 301.

[0121] In the electronic device 301 configured as described above, a pixel structure that suppresses cracks can be realized by applying the above-described photodetector 1 as the photodetector 303. This makes it possible to generate high-quality captured images with excellent durability.

[0122] 12. Example of Use of Image Sensor FIG. 29 is a diagram showing an example of use of the above-described photodetector 1 when it is an image sensor.

[0123] When the above-described photodetector 1 is an image sensor, it can be used in various cases for sensing light such as visible light, infrared light, ultraviolet light, and X-rays, for example, as follows.

[0124] ・Devices for taking images for viewing purposes, such as digital cameras and mobile devices with camera functions. ・Devices for traffic purposes, such as in-vehicle sensors that take images of the front, rear, surroundings, and interior of a car for safe driving such as automatic stopping, and for recognizing the driver's state, surveillance cameras that monitor moving vehicles and roads, and distance measuring sensors that measure distances between vehicles. ・Devices for home appliances such as TVs, refrigerators, and air conditioners that take images of user gestures and operate the device according to those gestures. ・Devices for medical and healthcare purposes, such as endoscopes and devices that take images of blood vessels by receiving infrared light. ・Devices for security purposes, such as surveillance cameras for crime prevention and cameras for person authentication. ・Devices for beauty purposes, such as skin measuring devices that take images of the skin and microscopes that take images of the scalp. ・Devices for sports purposes, such as action cameras and wearable cameras for sports, etc. ・Devices for agricultural purposes, such as cameras to monitor the condition of fields and crops.

[0125] 13. Application Example to Endoscopic Surgery System The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

[0126] FIG. 30 is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (the present technology) can be applied.

[0127] 30 shows an operator (doctor) 11131 performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 is composed of an endoscope 11100, other surgical tools 11110 such as an insufflation tube 11111 and an energy treatment tool 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are mounted.

[0128] The endoscope 11100 is composed of a lens barrel 11101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 11132, and a camera head 11102 connected to the base end of the lens barrel 11101. In the example shown, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may also be configured as a so-called flexible scope having a flexible lens barrel.

[0129] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101, and is irradiated via the objective lens toward an object to be observed inside the body cavity of the patient 11132. The endoscope 11100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0130] An optical system and an image sensor are provided inside the camera head 11102, and light reflected from the object of observation (observation light) is collected onto the image sensor by the optical system. The observation light is photoelectrically converted by the image sensor to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The image signal is sent to a camera control unit (CCU) 11201 as RAW data.

[0131] The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives an image signal from the camera head 11102 and performs various image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0132] Under the control of the CCU 11201, the display device 11202 displays an image based on an image signal that has been subjected to image processing by the CCU 11201.

[0133] The light source device 11203 is composed of a light source such as an LED (Light Emitting Diode), and supplies irradiation light to the endoscope 11100 when photographing the surgical area, etc.

[0134] The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of irradiation light, magnification, focal length, etc.) of the endoscope 11100.

[0135] The treatment tool control device 11205 controls the driving of the energy treatment tool 11112 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 11206 inflates the body cavity of the patient 11132 through the insufflation tube 11111 in order to ensure a clear field of view for the endoscope 11100 and a working space for the surgeon. The recorder 11207 is a device capable of recording various types of information related to the surgery. The printer 11208 is a device capable of printing various types of information related to the surgery in various formats such as text, images, or graphs.

[0136] The light source device 11203, which supplies illumination light to the endoscope 11100 when photographing the surgical site, can be configured from a white light source, such as an LED, a laser light source, or a combination of these. When the white light source is configured from a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, allowing the light source device 11203 to adjust the white balance of the captured image. In this case, it is also possible to time-share images corresponding to each RGB by irradiating the object of observation with laser light from each RGB laser light source and controlling the drive of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, color images can be obtained without providing a color filter to the image sensor.

[0137] Furthermore, the light source device 11203 may be controlled to change the intensity of light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 11102 in synchronization with the timing of the change in light intensity to acquire images in a time-division manner and combining the images, it is possible to generate an image with a high dynamic range that is free from so-called blocked-up shadows and blown-out highlights.

[0138] The light source device 11203 may also be configured to supply light in a predetermined wavelength band corresponding to special light observation. Special light observation, for example, utilizes the wavelength dependence of light absorption in body tissues to irradiate light with a narrower band than the light irradiated during normal observation (i.e., white light), thereby capturing high-contrast images of specific tissues, such as blood vessels on the surface of mucous membranes, known as narrow-band imaging. Alternatively, special light observation may be performed using fluorescence observation, in which images are obtained using fluorescence generated by irradiating excitation light. Fluorescence observation may involve irradiating excitation light onto body tissue and observing the fluorescence from the tissue (autofluorescence observation), or by locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 11203 may be configured to supply narrow-band light and / or excitation light corresponding to such special light observation.

[0139] FIG. 31 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG.

[0140] The camera head 11102 has a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 has a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other by a transmission cable 11400 so that they can communicate with each other.

[0141] The lens unit 11401 is an optical system provided at the connection portion with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is composed of a combination of multiple lenses including a zoom lens and a focus lens.

[0142] The imaging unit 11402 is composed of an imaging element. The imaging element constituting the imaging unit 11402 may be a single (single-chip type) or multiple (multi-chip type). When the imaging unit 11402 is composed of a multi-chip type, for example, each imaging element may generate an image signal corresponding to each of RGB, and a color image may be obtained by combining these signals. Alternatively, the imaging unit 11402 may be configured to have a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to 3D (dimensional) display. The 3D display allows the surgeon 11131 to more accurately grasp the depth of the biological tissue at the surgical site. Note that when the imaging unit 11402 is composed of a multi-chip type, multiple lens units 11401 may be provided corresponding to each imaging element.

[0143] Furthermore, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101, immediately after the objective lens.

[0144] The driving unit 11403 is configured by an actuator, and moves the zoom lens and focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera head control unit 11405. This allows the magnification and focus of the image captured by the imaging unit 11402 to be adjusted appropriately.

[0145] The communication unit 11404 is configured by a communication device for transmitting and receiving various information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 to the CCU 11201 via the transmission cable 11400 as RAW data.

[0146] Furthermore, the communication unit 11404 receives a control signal for controlling the driving of the camera head 11102 from the CCU 11201 and supplies the control signal to the camera head control unit 11405. The control signal includes information on the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value at the time of imaging, and / or information specifying the magnification and focus of the captured image.

[0147] The image capturing conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. In the latter case, the endoscope 11100 is equipped with so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

[0148] The camera head control unit 11405 controls the driving of the camera head 11102 based on a control signal received from the CCU 11201 via the communication unit 11404.

[0149] The communication unit 11411 is configured by a communication device for transmitting and receiving various information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

[0150] Furthermore, the communication unit 11411 transmits to the camera head 11102 a control signal for controlling the driving of the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, or the like.

[0151] The image processing unit 11412 performs various image processing operations on the image signal, which is RAW data sent from the camera head 11102 .

[0152] The control unit 11413 performs various controls related to the imaging of the surgical site, etc. by the endoscope 11100 and the display of the captured image obtained by imaging the surgical site, etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

[0153] Furthermore, the control unit 11413 displays the captured image showing the surgical site, etc., on the display device 11202 based on the image signal subjected to image processing by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition technologies. For example, the control unit 11413 can recognize surgical tools such as forceps, specific biological parts, bleeding, mist generated when using the energy treatment tool 11112, etc., by detecting the shape and color of the edges of objects included in the captured image. When displaying the captured image on the display device 11202, the control unit 11413 may use the recognition results to superimpose various surgical support information on the image of the surgical site. By superimposing the surgical support information and presenting it to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

[0154] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for communication of electrical signals, an optical fiber for optical communication, or a composite cable of these.

[0155] In the illustrated example, communication is performed wired using a transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

[0156] The foregoing has described an example of an endoscopic surgery system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the imaging unit 11402 of the camera head 11102, among the configurations described above. Specifically, the above-described light detection device 1 can be applied as the imaging unit 11402. By applying the technology according to the present disclosure to the imaging unit 11402, the camera head 11102 can be made smaller, while still achieving excellent durability and enabling clearer images of the surgical site to be obtained.

[0157] Although an endoscopic surgery system has been described as an example here, the technology disclosed herein may also be applied to other systems, such as a microsurgery system.

[0158] 14. Application Examples to Mobile Bodies The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of mobile body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0159] FIG. 32 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0160] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 32, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (Interface) 12053.

[0161] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0162] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0163] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0164] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0165] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0166] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the distance between vehicles, maintaining vehicle speed, vehicle collision warning, vehicle lane departure warning, etc.

[0167] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0168] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0169] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying the passengers of the vehicle or the outside of the vehicle of information. In the example of Fig. 32, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0170] FIG. 33 is a diagram showing an example of the installation position of the imaging unit 12031.

[0171] In FIG. 33, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0172] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided on the top of the windshield inside the vehicle cabin is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0173] 33 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0174] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for detecting a phase difference.

[0175] For example, based on distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the closest three-dimensional object on the path of the vehicle 12100 that is traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which travels autonomously without relying on driver operation.

[0176] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into categories such as two-wheeled vehicles, standard vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into those that are visible to the driver of the vehicle 12100 and those that are difficult to see. The microcomputer 12051 then determines the collision risk, which indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drivetrain control unit 12010.

[0177] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize pedestrians by determining whether or not a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching processing on a series of feature points that indicate the outline of an object to determine whether or not the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0178] The above describes an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the image capture unit 12031 of the above-described configuration. Specifically, the above-described light detection device 1 can be applied as the image capture unit 12031. By applying the technology according to the present disclosure to the image capture unit 12031, it is possible to obtain a more durable, easily visible captured image while reducing the size, and to acquire distance information. Furthermore, it is possible to reduce driver fatigue and increase the safety of the driver and the vehicle by using the obtained captured image and distance information.

[0179] In the above example, a photodetector in which the first conductivity type is P-type and the second conductivity type is N-type and electrons are used as signal charges has been described, but the present disclosure can also be applied to a photodetector in which holes are used as signal charges. That is, the first conductivity type can be N-type and the second conductivity type can be P-type, and the aforementioned semiconductor regions can be configured with semiconductor regions of opposite conductivity types.

[0180] The technology disclosed herein is not limited to application to photodetection devices that detect the distribution of incident light amount of visible light and capture it as an image, but can also be applied to photodetection devices that capture the distribution of incident amounts of infrared rays, X-rays, particles, etc. as an image, and in a broad sense, to photodetection devices in general (physical quantity distribution detection devices) such as fingerprint detection sensors that detect the distribution of other physical quantities such as pressure or capacitance and capture it as an image.

[0181] In this specification, a system refers to a collection of multiple components (devices, modules (components), etc.), regardless of whether all of the components are housed in the same housing. Therefore, multiple devices housed in separate housings and connected via a network, and a single device housed in a single housing with multiple modules, are both systems.

[0182] The embodiments of the technology of the present disclosure are not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the technology of the present disclosure.

[0183] The effects described in this specification are merely examples and are not intended to be limiting, and there may be effects other than those described in this specification.

[0184] The technology disclosed herein may employ the following configurations: (1) A photodetector including a pixel array section in which a plurality of pixels are arranged in row and column directions on a semiconductor substrate, the pixel array section including inter-pixel isolation sections between the pixels, the inter-pixel isolation sections including, in a plan view, first and second intersections and straight sections located between the first and second intersections, the first and second intersections including trench structures separating the semiconductor substrate from a first surface of the semiconductor substrate to an opposite second surface, the straight sections including, in a cross-sectional view, a semiconductor region that is a part of the semiconductor substrate and a trench structure. (2) The second surface of the semiconductor substrate is a light incident surface on which light is incident, opposite the first surface on which pixel transistors are formed, and the semiconductor region in the straight section is formed on the second surface side of the semiconductor substrate. (3) The photodetector according to (1) or (2), wherein the semiconductor region is composed of a semiconductor region of a second conductivity type opposite to a semiconductor region of a first conductivity type that constitutes a charge accumulation region of a photoelectric conversion unit of the pixel. (4) The photodetector according to any of (1) to (3), wherein the semiconductor region is also formed between the inter-pixel isolation unit and the photoelectric conversion unit. (5) The photodetector according to any of (1) to (4), wherein the inter-pixel isolation unit has an STI in a region on the first surface side of the semiconductor substrate. (6) The photodetector according to any of (1) to (5), wherein the inter-pixel isolation unit has a fixed charge film on a side surface of a trench. (7) The photodetector according to (6), wherein the linear portion of the inter-pixel isolation unit has the fixed charge film on the side, top surface, and bottom surface of the trench. (8) The photodetector according to any one of (6) to (7), further comprising a fixed charge film on the second surface of the semiconductor substrate, wherein the fixed charge film on the side surfaces of the trenches at the first intersection and the second intersection is connected to the fixed charge film on the second surface. (9) The photodetector according to any one of (1) to (8), further comprising an uneven structure on the second surface of the semiconductor substrate. (10) The photodetector according to any one of (1) to (9), wherein a fixed charge film is embedded in recesses of the uneven structure.(11) The photodetector according to any one of (1) to (10), wherein the concavo-convex structure is provided on a semiconductor region of the straight line portion. (12) The photodetector according to any one of (1) to (11), wherein the inter-pixel isolation portion has at least a fixed charge film and an insulating film. (13) The photodetector according to any one of (1) to (12), wherein the inter-pixel isolation portion has at least a fixed charge film and a transparent electrode. (14) The photodetector according to any one of (1) to (13), further comprising an insulating film above the second surface of the semiconductor substrate, wherein the insulating film is connected to the insulating film inside the trenches at the first intersection and the second intersection. (15) The photodetector according to any one of (1) to (13), further comprising a transparent electrode above the second surface of the semiconductor substrate, wherein the transparent electrode is connected to the transparent electrode inside the trenches at the first intersection and the second intersection. (16) The photodetector according to any one of (1) to (15), wherein the pixel has two photoelectric conversion units. (17) The photodetector according to any one of (1) to (16), wherein the inter-pixel isolation portion further has a third intersection portion at a position different from the first intersection portion and the second intersection portion, and the third intersection portion has a trench structure that separates the semiconductor substrate from the first surface to the second surface on the opposite side in a cross-sectional view. (18) The photodetector according to any one of (1) to (17), wherein all intersection portions of the inter-pixel isolation portion have trench structures that separate the semiconductor substrate from the first surface to the second surface on the opposite side in a cross-sectional view. (19) The photodetector according to any one of (1) to (18), which has an on-chip lens shared by four 2x2 pixels, and wherein a depth of a trench structure of the linear portion of the inter-pixel isolation portion is different between the inter-pixel isolation portion at a boundary of a sharing unit that shares the on-chip lens and the inter-pixel isolation portion inside the sharing unit. (20) The photodetector according to (19), wherein a depth of the trench structure of the linear portion of the inter-pixel isolation portion is shorter in the inter-pixel isolation portion inside the sharing unit than in the inter-pixel isolation portion at a boundary of a sharing unit that shares the on-chip lens.(21) The photodetector according to any one of (1) to (20), which has an on-chip lens shared by four 2x2 pixels, and wherein a composition of a material filled in the inter-pixel isolation portion is different between the inter-pixel isolation portion at a boundary of a sharing unit that shares the on-chip lens and the inter-pixel isolation portion inside the sharing unit. (22) The photodetector according to (21), wherein the inter-pixel isolation portion at the boundary of the sharing unit includes a fixed charge film and a first insulating material and a second insulating material having different refractive indices, and the inter-pixel isolation portion inside the sharing unit includes the fixed charge film and the first insulating material having a higher refractive index of the first insulating material and the second insulating material, and does not include the second insulating material having a lower refractive index. (23) The photodetector according to any one of (1) to (22), wherein the linear portion of the inter-pixel isolation portion has, in the cross-sectional view, a first trench structure that exists from the first surface side of the semiconductor substrate to a predetermined depth, a second trench structure that exists from the second surface side of the semiconductor substrate to a predetermined depth, and the semiconductor region that is a part of the semiconductor substrate. (24) The photodetector according to (23), wherein the second surface of the semiconductor substrate is a light incident surface onto which light is incident, opposite to the first surface on which pixel transistors are formed, and wherein a shallow trench isolation is provided in a region of the first surface side of the first trench structure of the inter-pixel isolation portion. (25) The photodetector according to any one of (23) to (24), wherein the second surface of the semiconductor substrate is a light incident surface on which light is incident, opposite to the first surface on which pixel transistors are formed, a fixed charge film and an insulating film are buried inside the first trench structure and the second trench structure, the fixed charge film inside the second trench structure is connected to the fixed charge film on the second surface, and the insulating film inside the second trench structure is connected to the insulating film on the second surface. (26) The photodetector according to any one of (25), wherein the material of the fixed charge film is any one of hafnium oxide, aluminum oxide, zirconium dioxide, and tantalum oxide, and the material of the insulating film is SiO2 or a composite material mainly composed of SiO2.(27) The photodetector according to any one of (23) to (26), wherein the first trench structure and the second trench structure have different compositions of materials filled therein. (28) The photodetector according to any one of (23) to (27), wherein a region is provided where the first trench structure and the second trench structure overlap with each other in a depth direction that is a direction perpendicular to the second surface of the semiconductor substrate. (29) The photodetector according to any one of (23) to (28), wherein the width of the second trench structure is set wider than the width of the first trench structure. (30) The photodetector according to any one of (23) to (29), wherein the first trench structure is disposed between two of the second trench structures in the cross-sectional view. (31) An electronic device including a photodetector device having a pixel array section in which a plurality of pixels are arranged in row and column directions on a semiconductor substrate, the pixel array section having inter-pixel separation sections provided between each pixel, the inter-pixel separation sections having, in a planar view, a first intersection and a second intersection and a straight section located between the first intersection and the second intersection, the first intersection and the second intersection having a trench structure separating the semiconductor substrate from a first surface of the semiconductor substrate to a second surface on the opposite side, in a cross-sectional view, and the straight section having a semiconductor region that is part of the semiconductor substrate and a trench structure in the cross-sectional view. (32) A photodetector comprising: a pixel array section in which a plurality of pixels are arranged in row and column directions on a semiconductor substrate; the pixel array section having inter-pixel separation sections provided between the pixels; the inter-pixel separation sections having, in a plan view, first and second intersection sections and straight sections located between the first and second intersection sections; the first and second intersection sections having a structure penetrating from a first surface of the semiconductor substrate to a second surface on the opposite side in a cross-sectional view; and the straight sections having a structure not penetrating the semiconductor substrate in the cross-sectional view.

[0185] REFERENCE SIGNS LIST 1 Photodetector, 2 Pixel, PD photodiode, 3 Pixel array section, 21 Semiconductor substrate, 22 Wiring layer, 23 Fixed charge film, 24 Insulating film, 25 Color filter, 26 Inter-pixel light-shielding film, 27 On-chip lens, 41 P-type semiconductor region, 42 N-type semiconductor region, 43 Inter-pixel isolation section, 43A Intersection section, 43B Linear section, 44 Fixed charge film, 45 Insulating film, 46 Air gap, 47 P-type semiconductor region, 211 Reflection suppression section, 221 Transparent electrode, 222 Transparent electrode, 301 Electronic device, 303 Photodetector, 401 High refractive index film, 421 First trench, 422, 422A Second trench, 422B Microtrench, 422C Second trench

Claims

1. A photodetector comprising: a pixel array section in which a plurality of pixels are arranged in both row and column directions on a semiconductor substrate; the pixel array section having inter-pixel separation sections between each pixel; the inter-pixel separation sections having, in a plan view, a first intersection and a second intersection and a straight section located between the first intersection and the second intersection; the first intersection and the second intersection having a trench structure in a cross-sectional view that separates the semiconductor substrate from a first surface of the semiconductor substrate to a second surface on the opposite side; and the straight section having a trench structure and a semiconductor region that is part of the semiconductor substrate in the cross-sectional view.

2. The photodetector according to claim 1, wherein the second surface of the semiconductor substrate is a light incident surface onto which light is incident, opposite the first surface on which pixel transistors are formed, and the semiconductor region of the linear portion is formed on the second surface side of the semiconductor substrate.

3. The photodetector according to claim 1, wherein the semiconductor region is composed of a semiconductor region of a second conductivity type opposite to a semiconductor region of a first conductivity type that constitutes a charge accumulation region of a photoelectric conversion unit of the pixel.

4. The photodetector according to claim 1, wherein the semiconductor region is also formed between the inter-pixel isolation section and the photoelectric conversion section.

5. The photodetector according to claim 1, wherein the inter-pixel isolation section has an STI in a region on the first surface side of the semiconductor substrate.

6. The photodetector according to claim 1, wherein the inter-pixel isolation section has a fixed charge film on the side surface of the trench.

7. The photodetector according to claim 6, wherein the linear portion of the inter-pixel isolation portion has the fixed charge film on the side, top and bottom surfaces of the trench.

8. The photodetector according to claim 6, further comprising a fixed charge film on the second surface of the semiconductor substrate, wherein the fixed charge film on the side surfaces of the trenches at the first intersection and the second intersection is connected to the fixed charge film on the second surface.

9. The photodetector according to claim 1, further comprising an uneven structure on the second surface of the semiconductor substrate.

10. The photodetector according to claim 9, wherein a fixed charge film is embedded in the recesses of the uneven structure.

11. The photodetector according to claim 9, wherein the concave-convex structure is provided on a semiconductor region of the linear portion.

12. The photodetector according to claim 1, wherein the inter-pixel isolation portion has at least a fixed charge film and an insulating film.

13. The photodetector according to claim 1, wherein the inter-pixel separating portion has at least a fixed charge film and a transparent electrode.

14. The photodetector according to claim 1, further comprising an insulating film above the second surface of the semiconductor substrate, the insulating film being connected to the insulating films inside the trenches at the first intersection and the second intersection.

15. The photodetector device according to claim 1, further comprising a transparent electrode above the second surface of the semiconductor substrate, the transparent electrode being connected to transparent electrodes inside the trenches at the first intersection and the second intersection.

16. The photodetector according to claim 1, wherein the pixel has two photoelectric conversion units.

17. The photodetector device according to claim 1, wherein the inter-pixel isolation portion further has a third intersection portion at a position different from the first intersection portion and the second intersection portion, and the third intersection portion has a trench structure that separates the semiconductor substrate from the first surface of the semiconductor substrate to the second surface on the opposite side in a cross-sectional view.

18. The photodetector device according to claim 1, wherein all intersections of the inter-pixel isolation portions have a trench structure that separates the semiconductor substrate from the first surface to the opposite second surface of the semiconductor substrate in a cross-sectional view.

19. The photodetector device according to claim 1, which has an on-chip lens shared by four 2x2 pixels, and wherein the depth of the trench structure of the linear portion of the inter-pixel isolation portion is different between the inter-pixel isolation portion at the boundary of the sharing unit that shares the on-chip lens and the inter-pixel isolation portion inside the sharing unit.

20. The photodetector device according to claim 19, wherein the depth of the trench structure of the linear portion of the inter-pixel isolation portion is shorter inside the shared unit than at the boundary of the shared unit that shares the on-chip lens.

21. The photodetector device according to claim 1, which has an on-chip lens shared by four 2x2 pixels, and the composition of the material embedded in the inter-pixel isolation portion differs between the inter-pixel isolation portion at the boundary of the sharing unit that shares the on-chip lens and the inter-pixel isolation portion inside the sharing unit.

22. The photodetector device described in claim 21, wherein the inter-pixel separation portion at the boundary of the shared unit includes a fixed charge film and a first insulating material and a second insulating material having different refractive indices, and the inter-pixel separation portion inside the shared unit includes the fixed charge film and the first insulating material having a higher refractive index among the first insulating material and the second insulating material, but does not include the second insulating material having a lower refractive index.

23. The photodetector device described in claim 1, wherein the linear portion of the inter-pixel isolation portion has, in the cross-sectional view, a first trench structure that exists from the first surface side of the semiconductor substrate to a predetermined depth, a second trench structure that exists from the second surface side of the semiconductor substrate to a predetermined depth, and the semiconductor region that is part of the semiconductor substrate.

24. The photodetector according to claim 23, wherein the second surface of the semiconductor substrate is a light incident surface on which light is incident, opposite to the first surface on which pixel transistors are formed, and wherein shallow trench isolation is provided in an area of ​​the inter-pixel isolation portion on the first surface side of the first trench structure.

25. The photodetector according to claim 23, wherein the second surface of the semiconductor substrate is a light incident surface on which light is incident, opposite to the first surface on which pixel transistors are formed; a fixed charge film and an insulating film are embedded inside the first trench structure and the second trench structure; the fixed charge film inside the second trench structure is connected to the fixed charge film on the second surface; and the insulating film inside the second trench structure is connected to the insulating film on the second surface.

26. The photodetector according to claim 25, wherein the material of the fixed charge film is either hafnium oxide, aluminum oxide, zirconium dioxide, or tantalum oxide, and the material of the insulating film is SiO2 or a composite material containing SiO2 as a main component.

27. The photodetector device according to claim 23, wherein the first trench structure and the second trench structure are filled with different materials.

28. The photodetector according to claim 23, wherein a region is provided in which the first trench structure and the second trench structure overlap in a depth direction that is a direction perpendicular to the second surface of the semiconductor substrate.

29. The photodetector device according to claim 23, wherein the width of the second trench structure is greater than the width of the first trench structure.

30. The photodetector according to claim 23, wherein the first trench structure is disposed between two of the second trench structures in the cross-sectional view.

31. An electronic device comprising a photodetector having a pixel array section in which a plurality of pixels are arranged in both row and column directions on a semiconductor substrate, the pixel array section having inter-pixel separation sections provided between each pixel, the inter-pixel separation sections having, in a plan view, a first intersection and a second intersection and a straight section located between the first intersection and the second intersection, the first intersection and the second intersection having a trench structure separating the semiconductor substrate from a first surface of the semiconductor substrate to a second surface on the opposite side, in a cross-sectional view, and the straight section having a semiconductor region that is part of the semiconductor substrate and a trench structure in the cross-sectional view.

32. A photodetector comprising: a pixel array section in which a plurality of pixels are arranged in row and column directions on a semiconductor substrate; the pixel array section having inter-pixel separation sections provided between each pixel; the inter-pixel separation sections having, in a plan view, first and second intersection sections and straight sections located between the first and second intersection sections; the first and second intersection sections having a structure that penetrates from a first surface of the semiconductor substrate to a second surface on the opposite side in a cross-sectional view; and the straight sections having a structure that does not penetrate the semiconductor substrate in the cross-sectional view.

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