Photodetector

Abstract

A first imaging device according to an embodiment of the present invention includes: a semiconductor substrate having opposing first and second surfaces and including pixels arranged in a matrix; a photoelectric conversion unit which is formed so as to be embedded in the semiconductor substrate for each pixel, and which generates an electric charge corresponding to the amount of received light by means of photoelectric conversion; a floating diffusion layer provided on the first surface between adjacent pixels and temporarily holding charges generated in the photoelectric conversion portion provided for each adjacent pixel; a first trench portion disposed to surround the pixels of the common floating diffusion layer and penetrating from the first surface to the second surface; a second diffusion layer disposed at least above the floating diffusion layer, extending from the second surface toward the first surface, and having a second trench portion at a bottom in the semiconductor substrate; and an oxide film provided in contact with the bottom.

Description

Technical Field

[0001] The present invention relates to a photodetector in which, for example, a floating diffusion layer is shared by a plurality of pixels. Background Art

[0002] For example, Patent Document 1 discloses an imaging element in which a through trench is provided between pixels each including a photoelectric conversion portion.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-145544 Summary of the invention

[0006] Thus, it is desired that a photodetector applied to an imaging device, for example, have improved performance.

[0007] It would be desirable to provide a photodetector with improved performance.

[0008] A first photodetector according to an embodiment of the present invention includes: a semiconductor substrate having a first surface and a second surface opposite to each other, the semiconductor substrate including a plurality of pixels arranged in a matrix; a plurality of photoelectric conversion portions formed in a manner embedded in the semiconductor substrate for each of the pixels and generating charges corresponding to the amount of received light by photoelectric conversion; a plurality of floating diffusion layers provided on the first surface of the semiconductor substrate between the plurality of pixels adjacent to each other, the plurality of floating diffusion layers temporarily retaining the charges generated in the plurality of photoelectric conversion portions provided for each of the pixels adjacent to each other; a first groove portion provided to surround the plurality of pixels sharing the floating diffusion layer and penetrate from the first surface of the semiconductor substrate to the second surface; a second groove portion provided at least above the plurality of floating diffusion layers and extending from the second surface of the semiconductor substrate toward the first surface, the second groove portion having a bottom located in the semiconductor substrate; and an oxide film provided to be in contact with the bottom of the second groove portion.

[0009] According to the first photodetector of the embodiment of the present invention, in a semiconductor substrate including a plurality of pixels arranged in a matrix and a floating diffusion layer disposed on the first surface between adjacent pixels, a first groove portion penetrating from the first surface of the semiconductor substrate to the second surface is disposed around the plurality of pixels sharing the floating diffusion layer; a second groove portion extending from the second surface of the semiconductor substrate toward the first surface and having a bottom located in the semiconductor substrate is disposed at least above the floating diffusion layer; and an oxide film is disposed to contact the bottom of the second groove portion. Thus, dispersion of the distance between the floating diffusion layer and the bottom of the second groove portion is reduced.

[0010] A second photodetector according to an embodiment of the present invention includes: a semiconductor substrate having a first surface and a second surface opposite to each other, the semiconductor substrate including a plurality of pixels arranged in a matrix; a plurality of photoelectric conversion portions formed in a manner embedded in the semiconductor substrate for each of the pixels and generating charges corresponding to the amount of received light by photoelectric conversion; a plurality of floating diffusion layers provided on the first surface of the semiconductor substrate between the plurality of pixels adjacent to each other, the plurality of floating diffusion layers temporarily retaining the charges generated in the plurality of photoelectric conversion portions provided for each of the pixels adjacent to each other; a first groove portion provided to surround the plurality of pixels sharing the floating diffusion layer and penetrate from the first surface to the second surface of the semiconductor substrate, the first groove portion having an inner wall on which a first pinning film is formed; and a second groove portion provided at least above the plurality of floating diffusion layers and extending from the second surface toward the first surface of the semiconductor substrate, the second groove portion having a bottom located in the semiconductor substrate and having an inner wall on which a second pinning film is formed, the second pinning film having a weaker pinning force than the first pinning film.

[0011] According to the second photodetector of the embodiment of the present invention, in a semiconductor substrate including a plurality of pixels arranged in a matrix and a floating diffusion layer disposed on a first surface between adjacent plurality of pixels, a first groove portion penetrating from the first surface of the semiconductor substrate to the second surface is disposed around a plurality of pixels sharing the floating diffusion layer, and a first pinning film is disposed on an inner wall of the first groove portion. In addition, a second groove portion extending from the second surface of the semiconductor substrate toward the first surface and having a bottom located in the semiconductor substrate is disposed at least above the floating diffusion layer, and a second pinning film having a weaker pinning force than the first pinning film is disposed on an inner wall of the second groove portion. Thus, pinning on the floating diffusion layer is reduced.

[0012] According to an embodiment of the present invention, a third light detector includes: a semiconductor substrate having a first surface and a second surface opposite to each other, the semiconductor substrate including a plurality of pixels arranged in a matrix; a plurality of photoelectric conversion units, the plurality of photoelectric conversion units being formed for each of the pixels in a manner embedded in the semiconductor substrate, and generating charges corresponding to the amount of received light through photoelectric conversion; a first separation unit, the first separation unit being arranged between the plurality of pixels adjacent to each other and extending from the second surface of the semiconductor substrate toward the first surface, the first separation unit having a bottom located in the semiconductor substrate; and a second separation unit, the second separation unit being arranged between the bottom of the first separation unit and the first surface, the width of the second separation unit on the bottom side of the first separation unit being greater than the width on the first surface side.

[0013] According to the third photodetector of the embodiment of the present invention, in a semiconductor substrate including a plurality of pixels arranged in a matrix, a first separation portion extending from the second surface of the semiconductor substrate toward the first surface and having a bottom located in the semiconductor substrate is provided between the plurality of pixels adjacent to each other; and a second separation portion having a wider width on the bottom side of the semiconductor substrate than on the first surface side is provided between the bottom of the first separation portion and the first surface. Thus, an element formation area of ​​the first surface of the semiconductor substrate is ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic cross-sectional view of an example of the configuration of a photodetector according to a first embodiment of the present invention.

[0015] Figure 2 It is shown Figure 1 A block diagram of the overall structure of the photodetector is shown.

[0016] Figure 3 yes Figure 1 The equivalent circuit diagram of the unit pixel is shown.

[0017] Figure 4A yes Figure 1 Schematic diagram of an example of a planar configuration of a light detector shown.

[0018] Figure 4B yes Figure 1 Schematic diagram of another planar configuration example of a photodetector shown.

[0019] Figure 5A yes Figure 1 Schematic diagram of another example of the cross-sectional shape of the oxide film shown.

[0020] Figure 5B yes Figure 1 Schematic diagram of another example of the cross-sectional shape of the oxide film shown.

[0021] Figure 5C yes Figure 1 Schematic diagram of another example of the cross-sectional shape of the oxide film shown.

[0022] Figure 5D yes Figure 1 Schematic diagram of another example of the cross-sectional shape of the oxide film shown.

[0023] Fig. 6A yes Figure 1 Schematic cross-sectional view illustrating a method for manufacturing a light detector is shown.

[0024] Figure 6B yes Fig. 6A Schematic cross-sectional view of the following steps.

[0025] Figure 6C yes Figure 6B Schematic cross-sectional view of the following steps.

[0026] Fig.6D yes Figure 6C Schematic cross-sectional view of the following steps.

[0027] Fig. 6E yes Fig.6D Schematic cross-sectional view of the following steps.

[0028] Fig. 6F yes Fig. 6E Schematic cross-sectional view of the following steps.

[0029] Figure 6G yes Fig. 6F Schematic cross-sectional view of the following steps.

[0030] Figure 6H yes Figure 6G Schematic cross-sectional view of the following steps.

[0031] Figure 7 : is a schematic cross-sectional view of a configuration example of a photodetector according to Modification 1 of the present invention.

[0032] Figure 8 is a schematic cross-sectional view of an example of the configuration of a photodetector according to a second embodiment of the present invention.

[0033] Fig. 9 1 is a schematic diagram showing an example of a planar structure of a photodetector according to Modification 2 of the present invention.

[0034] Fig.10 2 is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 3 of the present invention.

[0035] Fig.11is a schematic cross-sectional view of an example of the configuration of a photodetector according to a third embodiment of the present invention.

[0036] Fig. 12A yes Fig.11 Schematic cross-sectional view illustrating a method for manufacturing a light detector is shown.

[0037] Fig. 12B yes Fig. 12A Schematic cross-sectional view of the following steps.

[0038] Fig. 12C yes Fig. 12B Schematic cross-sectional view of the following steps.

[0039] Fig.12D yes Fig. 12C Schematic cross-sectional view of the following steps.

[0040] Fig.13 2 is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 4 of the present invention.

[0041] Fig.14A yes Fig.13 Schematic cross-sectional view illustrating a method for manufacturing a light detector is shown.

[0042] Fig. 14B yes Fig.14A Schematic cross-sectional view of the following steps.

[0043] Fig. 14C yes Fig. 14B Schematic cross-sectional view of the following steps.

[0044] Fig.15 is a schematic cross-sectional view of an example of the configuration of a photodetector according to a fourth embodiment of the present invention.

[0045] Fig.16A yes Fig.15 Schematic cross-sectional view illustrating a method for manufacturing a light detector is shown.

[0046] Fig. 16B yes Fig.16A Schematic cross-sectional view of the following steps.

[0047] Fig. 16C yes Fig. 16B Schematic cross-sectional view of the following steps.

[0048] Fig.17A yes Fig.15 Schematic cross-sectional view illustrating a method for manufacturing a light detector is shown.

[0049] Fig. 17B yes Fig.17A Schematic floor plan of the following steps.

[0050] Fig. 17C yes Fig. 17B Schematic floor plan of the following steps.

[0051] Fig.17D yes Fig. 17C Schematic floor plan of the following steps.

[0052] Fig.18 1 is a schematic diagram showing an example of a planar structure of a photodetector according to Modification 5 of the present invention.

[0053] Fig.19 is a schematic cross-sectional view of an example of the configuration of a photodetector according to a fifth embodiment of the present invention.

[0054] Fig. 20A yes Fig.19 Schematic diagram of an example of a planar configuration of a light detector shown.

[0055] Fig. 20B yes Fig.19 Schematic diagram of another planar configuration example of a photodetector shown.

[0056] Fig.21 is a schematic cross-sectional view of another configuration example of a photodetector according to a fifth embodiment of the present invention.

[0057] Fig.22A yes Fig.21 Schematic cross-sectional view illustrating a method for manufacturing a light detector is shown.

[0058] Fig. 22B yes Fig.22A Schematic cross-sectional view of the following steps.

[0059] Fig. 22C yes Fig. 22B Schematic cross-sectional view of the following steps.

[0060] Fig.22D yes Fig. 22C Schematic cross-sectional view of the following steps.

[0061] Fig.22E yes Fig.22D Schematic cross-sectional view of the following steps.

[0062] Fig.23A yes Fig. 22C Illustrative schematic plan view of the steps shown.

[0063] Fig. 23B Schematic diagram of an example of the cross-sectional shape of the widened portion.

[0064] Fig.23C 2 is a schematic diagram showing another example of the cross-sectional shape of the widened portion.

[0065] Fig.23D 2 is a schematic diagram showing another example of the cross-sectional shape of the widened portion.

[0066] Fig.24 2 is a schematic cross-sectional view of a configuration example of a photodetector according to Modification 6 of the present invention.

[0067] Fig.25 2 is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 7 of the present invention.

[0068] Fig.26 yes Fig.25 Schematic diagram of an example of a planar configuration of a light detector shown.

[0069] Fig. 27 It is shown that the use Figure 2 A block diagram of an example configuration of an electronic device of a photodetector is shown.

[0070] Fig.28A is used Figure 2 The photodetector shown is a schematic diagram of an example of the overall configuration of a light detection system.

[0071] Fig.28B It is shown Fig.28A A diagram showing an example of a circuit configuration of a photodetection system.

[0072] Fig.29 is a diagram showing a schematic configuration example of an endoscopic surgery system.

[0073] Fig.30 is a block diagram showing a functional configuration example of a camera head and a camera control unit (CCU).

[0074] Fig.31 is a block diagram showing a schematic configuration example of a vehicle control system.

[0075] Fig.32 It is a diagram for assisting in explaining an example of the installation positions of the vehicle exterior information detection unit and the imaging unit.

[0076] Fig.33 is a schematic cross-sectional view of an example of the configuration of a photodetector according to a sixth embodiment of the present invention.

[0077] Fig.34 is with Fig.33 Schematic diagram of an example of a planar configuration corresponding to line AA in the photodetector shown.

[0078] Fig.35 is with Fig.33 Schematic diagram of an example of a planar configuration corresponding to line BB in the photodetector shown.

[0079] Fig.36Ais with Fig.33 Schematic diagram of an example of a plane configuration corresponding to line CC in the photodetector shown.

[0080] Fig.36B is with Fig.33 Schematic diagram of another planar configuration example corresponding to line CC in the photodetector shown.

[0081] Fig.37A yes Fig.33 Schematic cross-sectional view illustrating an example of a method for manufacturing an element separation portion shown.

[0082] Fig.37B yes Fig.37A Schematic cross-sectional view of the following steps.

[0083] Fig.37C yes Fig.37B Schematic cross-sectional view of the following steps.

[0084] Fig.37D yes Fig.37C Schematic cross-sectional view of the following steps.

[0085] Fig.37E yes Fig.37D Schematic cross-sectional view of the following steps.

[0086] Fig.37F yes Fig.37E Schematic cross-sectional view of the following steps.

[0087] Figure 37G yes Fig.37F Schematic cross-sectional view of the following steps.

[0088] Fig.37H yes Figure 37G Schematic cross-sectional view of the following steps.

[0089] Fig.38A yes Fig.33 Schematic cross-sectional view illustrating another example of a method for manufacturing an element separation portion shown.

[0090] Fig.38B yes Fig.38A Schematic cross-sectional view of the following steps.

[0091] Fig.38C yes Fig.38B Schematic cross-sectional view of the following steps.

[0092] Fig.38D yes Fig.38C Schematic cross-sectional view of the following steps.

[0093] Fig.38E yes Fig.38D Schematic cross-sectional view of the following steps.

[0094] Fig.38F yes Fig.38E Schematic cross-sectional view of the following steps.

[0095] Figure 38G yes Fig.38F Schematic cross-sectional view of the following steps.

[0096] Fig.39 is a schematic cross-sectional view of another configuration example of a photodetector according to a sixth embodiment of the present invention.

[0097] Fig.40 2 is a schematic cross-sectional view of a configuration example of a photodetector according to Modification 8 of the present invention.

[0098] Fig.41 is with Fig.40 Schematic diagram of an example of a planar configuration corresponding to line AA in the photodetector shown.

[0099] Fig.42 is with Fig.40 Schematic diagram of an example of a planar configuration corresponding to line BB in the photodetector shown.

[0100] Fig.43 is with Fig.40 Schematic diagram of an example of a plane configuration corresponding to line CC in the photodetector shown.

[0101] Fig.44A yes Fig.40 Schematic cross-sectional view illustrating an example of a method for manufacturing an element separation portion shown.

[0102] Fig.44B yes Fig.44A Schematic cross-sectional view of the following steps.

[0103] Fig.44C yes Fig.44B Schematic cross-sectional view of the following steps. DETAILED DESCRIPTION

[0104] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following description is only a specific example of the present invention, and the present invention should not be limited to each of the following aspects. In addition, the present invention is not limited to the arrangement, size, size ratio, etc. of each component shown in the accompanying drawings. It should be noted that the description will be given in the following order.

[0105] 1. First Embodiment (Example of a Photodetector Including an Oxide Film at the Bottom of a Separation Section Provided Above an FD)

[0106] 2. Modification 1 (Example of Providing a P-Type Diffusion Region on the Outer Wall of the Separation Section)

[0107] 3. Second Embodiment (Example of a Photodetector Including an Etching Inhibiting Layer at the Bottom of a Separation Section Provided Above an FD)

[0108] 4. Modification 2 (Another example of the position where the etching inhibiting layer is formed)

[0109] 5. Modification 3 (Another example of the position where the etching inhibiting layer is formed)

[0110] 6. Third Embodiment (Example of a Photodetector: A pinning film is formed on the inner wall of a separation portion disposed above the FD and exposed to the bottom, wherein the pinning film is weaker than a pinning film disposed on another separation portion)

[0111] 7. Modification 4 (Example of a photodetector: There is no pinning force at the bottom of the separation portion provided above the FD)

[0112] 8. Fourth Embodiment (Example of a Photodetector in Which a Pinning Film is Formed on the Inner Wall of a Separation Section Provided Above an FD, Where the Pinning Film is Weaker Than a Pinning Film Provided on Another Separation Section)

[0113] 9. Modification 5 (Another example of the planar shape of the separation portion provided above the FD)

[0114] 10. Fifth Embodiment (Example of Photodetector Provided with T-Shaped Element Separation Section)

[0115] 11. Modification 6 (Another example of a photodetector having a T-shaped element separator)

[0116] 12. Modification 7 (Another example of a photodetector having a T-shaped element separator)

[0117] 13. Sixth Embodiment (Example of Photodetector Having a Void in an Element Separation Section)

[0118] 14. Modification 8 (Another example of a photodetector having a gap in the element separation portion)

[0119] 15. Application Examples

[0120] 16. Practical application examples

[0121] <1. First Embodiment>

[0122] Figure 1 A cross-sectional configuration example of a photodetector (photodetector 1 ) according to a first embodiment of the present invention is schematically shown. Figure 2 Show Figure 1The overall configuration example of the photodetector 1 shown. The photodetector 1 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or the like used in electronic devices such as a digital still camera or a video camera, and includes a pixel section (pixel section 100A) as an imaging area in which a plurality of pixels are two-dimensionally arranged in a matrix. The photodetector 1 is, for example, a so-called back-illuminated photodetector in such a CMOS image sensor or the like.

[0123] In the photodetector 1 according to the present embodiment, a plurality of unit pixels P are arranged in a matrix. In addition, in a semiconductor substrate 10 in which a floating diffusion (FD) 19 is provided on a surface (surface 10S1) between a plurality of unit pixels P adjacent to each other, a separation portion 16 is provided around the outer periphery of a plurality of unit pixels P sharing the FD 19. The separation portion 16 penetrates a pair of surfaces (surface 10S1 and surface 10S2) of the semiconductor substrate 10 that are opposite to each other. A separation portion 17 is provided above the FD 19. The separation portion 17 extends from the surface 10S2 of the semiconductor substrate 10 toward the surface 10S1 thereof, and has a bottom located in the semiconductor substrate 10. An oxide film 18 is provided at the bottom of the separation portion 17.

[0124] [Schematic Structure of Photodetector]

[0125] Figure 2 An overall configuration example of the photodetector 1 is shown.

[0126] The photodetector 1 is, for example, a CMOS image sensor. The photodetector 1 acquires incident light (image light) from a subject through an optical lens system (not shown), converts the amount of incident light formed as an image on an imaging surface into an electrical signal in units of pixels, and outputs the electrical signal as a pixel signal. The photodetector 1 includes a pixel portion 100A as an imaging area on a semiconductor substrate 10. In addition, in the peripheral area of ​​the pixel portion 100A, the photodetector 1 also includes, for example, a vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and an input / output terminal 116.

[0127] The pixel section 100A includes, for example, a plurality of unit pixels P arranged two-dimensionally in a matrix form. For example, the unit pixel P is provided with a pixel drive line Lread (specifically, a row selection line and a reset control line) for each pixel row wiring, and a vertical signal line Lsig for each pixel column wiring. The pixel drive line Lread transmits a drive signal for reading a signal from a pixel. One end of the pixel drive line Lread is connected to an output end of the vertical drive circuit 111 corresponding to each row.

[0128] The vertical drive circuit 111 is a pixel drive section composed of a shift register, an address decoder, and the like, and drives the unit pixels P of the pixel section 100A row by row, for example. Signals output from the respective unit pixels P in the pixel row selectively scanned by the vertical drive circuit 111 are supplied to the column signal processing circuit 112 through the respective vertical signal lines Lsig. The column signal processing circuit 112 is composed of an amplifier, a horizontal selection switch, and the like provided for each vertical signal line Lsig.

[0129] The horizontal driving circuit 113 is composed of a shift register, an address decoder, etc. The horizontal driving circuit 113 sequentially drives the horizontal selection switches of the column signal processing circuit 112 while scanning the horizontal selection switches. Through the selective scanning of the horizontal driving circuit 113, the signal of each pixel transmitted through each vertical signal line Lsig can be sequentially output to the horizontal signal line 121, and transmitted to the outside of the semiconductor substrate 10 through the horizontal signal line 121.

[0130] The output circuit 114 processes the signals sequentially supplied from the column signal processing circuits 112 through the horizontal signal line 121 and outputs the signals. The output circuit 114 performs, for example, only buffering in some cases and performs black level adjustment, column difference correction, various digital signal processing, etc. in other cases.

[0131] The circuit portion including the vertical drive circuit 111, the column signal processing circuit 112, the horizontal drive circuit 113, the horizontal signal line 121, and the output circuit 114 may be directly formed on the semiconductor substrate 10, or may be provided on an external control IC. In addition, the circuit portion may also be formed on another substrate connected by a cable or the like.

[0132] The control circuit 115 receives a clock supplied from outside the semiconductor substrate 10, data for indicating an operation mode, and the like, and also outputs data such as internal information of the photodetector 1. The control circuit 115 also includes a timing generator for generating various timing signals, and controls the driving of peripheral circuits including the vertical driving circuit 111, the column signal processing circuit 112, the horizontal driving circuit 113, and the like according to the various timing signals generated by the timing generator.

[0133] The input / output terminal 116 exchanges signals with the outside.

[0134] [Circuit structure of unit pixel]

[0135] Figure 3 Show Figure 1 An example of a readout circuit of a unit pixel P of the photodetector 1 is shown.

[0136] In the pixel section 100A, as described above, a plurality of unit pixels P are arranged two-dimensionally in a matrix. More specifically, a unit cell U including a plurality of unit pixels P is used as a repetitive unit and is repeatedly arranged in an array including a row direction and a column direction. For example, one unit cell U includes four unit pixels P. The four unit pixels P share a floating diffusion portion FD and a readout circuit. Here, the term "shared" means that the outputs of the four unit pixels P are input to a common floating diffusion portion FD and a readout circuit.

[0137] Each unit pixel P includes components that are common to each other. Figure 3 In order to distinguish the components of the unit pixel P from each other, an identification number (1, 2, 3, or 4) is assigned to the end of the symbol of the component of each unit pixel P. Hereinafter, in the case where it is necessary to distinguish the components of the respective unit pixels P from each other, the identification number is assigned to the end of the symbol of the component of each unit pixel P; however, in the case where it is not necessary to distinguish the components of the respective unit pixels P from each other, the identification number at the end of the symbol of the component of each unit pixel P is omitted.

[0138] Each unit pixel P includes, for example, a photodiode PD, a transfer transistor TR electrically connected to the photodiode PD, and a floating diffusion FD that temporarily holds the charge output from the photodiode PD through the transfer transistor TR. The photodiode PD performs photoelectric conversion to generate a charge corresponding to the amount of light received. The cathode of the photodiode PD is electrically connected to the source of the transfer transistor TR, and the anode of the photodiode PD is electrically connected to a reference potential line (e.g., ground). The drain of the transfer transistor TR is electrically connected to the floating diffusion FD, and the gate of the transfer transistor TR is electrically connected to the pixel drive line Lread. The transfer transistor TR is, for example, a CMOS (complementary metal oxide semiconductor) transistor.

[0139] As described above, the floating diffusion FD shared by the four unit pixels P is electrically connected to the input of the common readout circuit. The readout circuit includes, for example, a reset transistor RST, a selection transistor SEL, and an amplifier transistor AMP. Note that the selection transistor SEL can be omitted as needed. The source of the reset transistor RST (the input of the readout circuit) is electrically connected to the floating diffusion FD, and the drain of the reset transistor RST is electrically connected to the power supply line VDD and the drain of the amplifier transistor AMP. The gate of the reset transistor RST is electrically connected to the pixel drive line Lread. The source of the amplifier transistor AMP is electrically connected to the drain of the selection transistor SEL, and the gate of the amplifier transistor AMP is electrically connected to the source of the reset transistor RST. The source of the selection transistor SEL (the output of the readout circuit) is electrically connected to the vertical signal line Lsig, and the gate of the selection transistor SEL is electrically connected to the pixel drive line Lread.

[0140] When the transfer transistor TR is in the on state, the transfer transistor TR transfers the charge of the photodiode PD to the floating diffusion FD. Figure 1 As shown, the gate of the transfer transistor TR includes a vertical transfer gate 31 and is formed on the surface (surface 10S1) of the semiconductor substrate 10. The reset transistor RST resets the potential of the floating diffusion FD to a predetermined potential. When the reset transistor RST is in the on state, the potential of the floating diffusion FD is reset to the potential of the power supply line VDD. The selection transistor SEL controls the output timing of the pixel signal from the readout circuit. The amplifier transistor AMP generates a voltage signal corresponding to the charge level maintained in the floating diffusion FD as a pixel signal. The amplifier transistor AMP constitutes a source follower amplifier and outputs a pixel signal having a voltage corresponding to the charge level generated in the photodiode PD. When the selection transistor SEL is in the on state, the amplifier transistor AMP amplifies the potential of the floating diffusion FD and outputs a voltage corresponding to the potential to the column signal processing circuit 112 through the vertical signal line Lsig. The reset transistor RST, the amplifier transistor AMP and the selection transistor SEL are, for example, CMOS transistors.

[0141] Note that the readout circuit may include, for example, an FD transfer transistor FDG. The FD transfer transistor FDG is provided, for example, between the source of the reset transistor RST and the gate of the amplifier transistor AMP.

[0142] [Structure of unit pixel]

[0143] Figure 4A and 4B Schematically shown respectively Figure 1 The planar configuration example of the photodetector 1 is shown. Note that Figure 1 Corresponding to the Figure 4A A cross section along line II is shown.

[0144] The unit pixel P is described below taking the case of a backside illumination type as an example; however, the present technology is also applicable to a frontside illumination type.

[0145] The unit pixel P includes a photodiode (PD) 11, which is a photoelectric conversion element formed to be embedded in a semiconductor substrate 10 having a pair of surfaces (surface 10S1 and surface 10S2) facing each other. A p-type region 13 is formed on the light incident side S1 side of the PD 11, that is, the back side (surface 10S2) side of the semiconductor substrate 10). A p-well 12 is formed as an active region on the side of the PD 11 opposite to the light incident side S1, that is, the front side (surface 10S1) side of the semiconductor substrate 10. The p-well 12 includes, for example, an FD 19, a transfer transistor TR, and pixel transistors constituting a readout circuit (for example, a reset transistor RST, a selection transistor SEL, and an amplifier transistor AMP). The p-well 12 also includes an element separation portion 15 having a shallow trench isolation (STI: Shallow Trench Isolation) structure and separating pixel transistors, and the like.

[0146] The separation parts 16 and 17 are provided between the adjacent unit pixels P. The separation part 16 is provided between the adjacent unit cells U. For example, the separation part 16 is provided between the adjacent unit pixels P and the adjacent unit cells U. x ) film or the like, together with the element separation portion 15 formed by the semiconductor substrate 10, constitute a full trench isolation (FTI: Full Trench Isolation) structure. The FTI structure extends from the surface 10S1 of the semiconductor substrate 10 to its surface 10S2. The separation portion 17 is provided between a plurality of unit pixels P that share the FD 19. The separation portion 17 extends from the surface 10S2 of the semiconductor substrate 10 toward its surface 10S1, and has a deep trench isolation (DTI: Deep Trench Isolation) structure having a bottom located in the semiconductor substrate 10. For example, the separation portion 17 provided in the semiconductor substrate 10 includes an oxide film 18 at the bottom, and the width of the oxide film 18 is greater than the width of the separation portion 17. An n-type diffusion region 14 is provided between the PD 11 and the separation portions 16, 17.

[0147] On the light incident side S1 (surface 10S2 side of the semiconductor substrate 10), the unit pixel P includes a light shielding film 41, a color filter 42, and an on-chip lens 43 provided between adjacent unit pixels P. On the surface 10S1 of the semiconductor substrate 10 on the opposite side to the light incident side S1 of the unit pixel P, a multilayer wiring layer 30 is provided.

[0148] The light shielding film 41 is intended to prevent light from leaking into adjacent unit pixels P, and is disposed between adjacent unit pixels P, specifically, at a boundary position between color filters 42 that transmit mutually different color light beams. Examples of constituent materials of the light shielding film 41 include conductive materials having light shielding properties. Specific examples thereof include tungsten (W), silver (Ag), copper (Cu), aluminum (Al), and alloys of Al and Cu.

[0149] The color filter 42 includes, for example, a red color filter 42R that selectively transmits red light (R), a green color filter 42G that selectively transmits green light (G), and a blue color filter 42B that selectively transmits blue light (B). As for the color filters 42R, 42G, and 42B, for example, for each unit cell U, four green filters 42G are arranged on a diagonal line, and the red filter 42R and the blue filter 42B are arranged one by one on an orthogonal diagonal line. For example, in each unit cell U provided with the color filters 42R, 42G, and 42B, a light beam of a corresponding color is detected in a plurality of PDs 11 in the unit cell U. That is, in the pixel portion 100A, the unit cells U that respectively detect red light (R), green light (G), and blue light (B) are arranged in a Bayer pattern.

[0150] For example, Figure 1 As shown in FIG. 1 , the on-chip lens 43 collects incident light on the PD 11 and is provided for each unit pixel P. The on-chip lens 43 may be made of, for example, silicon oxide (SiO x ) or silicon nitride (SiN x ) or the like. In addition, the on-chip lens 43 may also be formed using an organic material having a high refractive index such as an episulfide-based resin, a thietane compound, or a resin thereof.

[0151] The multilayer wiring layer 30 is provided with, for example, a pixel transistor for constituting a readout circuit. Specifically, for example, a vertical transfer gate 31 of the transfer transistor TR is provided to extend from the surface 10S1 of the semiconductor substrate 10 at a depth reaching the PD 11. A side wall 32 is provided around the transfer gate 31 provided on the surface 10S1 of the semiconductor substrate 10. The side wall and the bottom surface of the transfer gate 31 extending in the semiconductor substrate 10 are covered with an insulating film 21. A plurality of wiring layers 33 and a plurality of wiring layers 34 are further stacked in the multilayer wiring layer 30, an interlayer insulating layer 35 is interposed between these wiring layers, and, for example, the wiring layer 33 and the FD 19 are electrically connected to each other through a through-hole interconnection V1. In the multilayer wiring layer 30, in addition to the above-mentioned readout circuit, for example, a vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and an input / output terminal 116 are formed.

[0152] The separation portions 16 and 17 and the oxide film 18 will be described in detail below.

[0153] The separation portion 16 corresponds to the "first groove portion" of the present invention, and is provided between the mutually adjacent unit cells U as described above. In other words, for example, Figure 4AAs shown, the separation section 16 is provided to surround the outer periphery of four unit pixels arranged in two rows and two columns and sharing the FD 19, for example, and is provided in a grid pattern in the pixel section 100A. The separation section 16 electrically separates adjacent unit cells U from each other, and extends, for example, from the surface 10S2 side of the semiconductor substrate 10 toward the surface 10S1 side thereof. As described above, the separation section 16 constitutes an FTI structure together with the element separation section 15 provided on the surface 10S1 of the semiconductor substrate 10. The FTI structure penetrates from the surface 10S1 of the semiconductor substrate 10 to the surface 10S2 thereof.

[0154] The separation portion 16 is composed of a pinning film 16A and an insulating film 16B. The pinning film 16A is provided on the inner wall and bottom surface of the groove forming the separation portion 16 and has, for example, positive fixed charge. The insulating film 16B fills the groove.

[0155] Examples of the constituent material of the pinning film 16A include hafnium oxide (HfO x ), aluminum oxide (AlO x )、ZrO x ), tantalum oxide (TaO x ), titanium oxide (TiO x ), lanthanum oxide (LaO x ), praseodymium oxide (PrO x ), cerium oxide (CeO x ), neodymium oxide (NdO x ), promethium oxide (PmO x ), samarium oxide (SmO x ), europium oxide (EuO x ), Gadolinium oxide (GdO x ), terbium oxide (TbO x ), Dysprosium oxide (DyO x ), holmium oxide (HoO x ), thulium oxide (TmO x ), Ytterbium oxide (YbO x ), Lutetium oxide (LuO x ), yttrium oxide (YO x ), Hafnium Nitride (HfN x ), aluminum nitride (AlN x ), Hafnium Oxynitride (HfO x N y ) and aluminum oxynitride (AlO x N y ). The pinning film 16A may be a single-layer film, or a stacked film including different materials.

[0156] Examples of the constituent material of the insulating film 16B include silicon oxide (SiO x )membrane.

[0157] In addition, a conductive film having light-shielding properties may be embedded in the pinning film 16A of the groove forming the separation portion 16. Specific examples thereof include tungsten (W), silver (Ag), copper (Cu), aluminum (Al), and alloys of Al and Cu. The conductive film may be a single-layer film, or a stacked film containing different materials. Examples of stacked films include stacked films of Al and cobalt (Co) or stacked films of Al and Ti constituting so-called barrier metals. As described above, by embedding a conductive film having light-shielding properties in the pinning film 16A, adjacent unit cells U can be electrically and optically separated from each other.

[0158] The separation portion 17 corresponds to the "second groove portion" of the present invention. As described above, for example, the separation portion 17 is provided between a plurality of unit pixels P sharing the FD 19 and is in contact with the separation portion 16 on the outer periphery of the unit cell U. In addition to the above, for example, Figure 4B As shown, the separation portion 17 may be selectively provided only above the FD 19 located near the intersection of four unit pixels constituting the unit cell U and arranged, for example, in two rows and two columns. At this time, the separation portion 16 extends from the outer periphery of the unit cell U toward the separation portion 17 between the adjacent unit pixels P constituting the unit cell U, and contacts the separation portion 17 near the FD 19 in a plan view. For example, as described above, the separation portion 17 electrically separates the adjacent unit pixels P in the unit cell U from each other, and extends from the surface 10S2 side of the semiconductor substrate 10 toward the surface 10S1 side thereof; the separation portion 17 has a DTI structure having a bottom located in the semiconductor substrate 10, specifically, having a bottom at the interface or inside the p-well 12.

[0159] The separation portion 17 is composed of, for example, a pinning film 17A and an insulating film 17B in the same manner as the separation portion 16. The pinning film 17A is provided on the inner wall and bottom surface of the groove forming the separation portion 17 and has, for example, positive fixed charge. The insulating film 17B fills the groove.

[0160] Examples of the constituent material of the pinning film 17A include hafnium oxide (HfO x ), aluminum oxide (AlO x )、ZrO x ), tantalum oxide (TaO x ), titanium oxide (TiO x ), lanthanum oxide (LaO x ), praseodymium oxide (PrO x ), cerium oxide (CeO x ), neodymium oxide (NdO x ), promethium oxide (PmO x ), samarium oxide (SmO x ), europium oxide (EuOx ), Gadolinium oxide (GdO x ), terbium oxide (TbO x ), Dysprosium oxide (DyO x ), holmium oxide (HoO x ), thulium oxide (TmO x ), Ytterbium oxide (YbO x ), Lutetium oxide (LuO x ), yttrium oxide (YO x ), Hafnium Nitride (HfN x ), aluminum nitride (AlN x ), Hafnium Oxynitride (HfO x N y ) and aluminum oxynitride (AlO x N y ). The pinning film 17A may be a single-layer film, or a stacked film including different materials. The pinning film 17A corresponds to a specific example of the "first pinning film" of the present invention.

[0161] Examples of the constituent material of the insulating film 17B include silicon oxide (SiO x ).

[0162] In addition, a conductive film having light-shielding properties may be embedded in the pinning film 17A of the groove forming the separation portion 17. Specific examples thereof include tungsten (W), silver (Ag), copper (Cu), aluminum (Al), and alloys of Al and Cu. The conductive film may be a single-layer film, or a stacked film comprising different materials. Examples of stacked films include stacked films of Al and cobalt (Co) or stacked films of Al and Ti constituting so-called barrier metals. As described above, by embedding a conductive film having light-shielding properties in the pinning film 17A, adjacent unit pixels P in the unit unit U can be electrically and optically separated from each other.

[0163] The oxide film 18 corresponds to a specific example of the "oxide film" of the present invention, and is provided in contact with the bottom of the separation portion 17 formed at the interface or inside the p-well 12. In other words, the oxide film 18 is provided in contact with the bottom of the separation portion 17 located in the p-well 12. Figure 6G ), the oxide film 18 functions as an etching stopper film and reduces dispersion of the distance between the separation portion 17 and the FD 19. Figure 1 , 4A As shown in other figures, the oxide film 18 is provided to have a larger width in the direction of the XZ plane than the separation portion 17 .

[0164] For example, the cross-sectional shape of the oxide film 18 may be as follows Figure 1 The rectangle shown, or it can be Figure 5A Alternatively, a trapezoidal shape such as Figure 5B A rectangle with a notch at the corner on the surface 10S1 side as shown, or a Figure 5C , Figure 5D The rectangle shown has rounded corners on the surface 10S1 side.

[0165] The oxide film 18 can be formed using, for example, a material having an etching rate lower than that of the silicon substrate constituting the semiconductor substrate 10. In addition, the constituent material of the oxide film 18 is preferably selected from a material having no fixed charge or a material having a weaker pinning force than the pinning force of the pinning film 17A formed on the inner wall or the bottom surface of the separation portion 17. Thus, it is possible to relax the pinning of holes by the pinning film 17A, thereby relaxing, for example, the electric field with respect to the n-type FD 19. Examples of such materials include silicon oxide (SiO x ), silicon nitride (SiN x ) and high dielectric constant (high-k) materials.

[0166] [Photodetector Manufacturing Method]

[0167] The photodetector 1 can be formed, for example, as follows.

[0168] First, if Fig. 6A As shown, for example, STI is formed on the surface 10S1 of the semiconductor substrate 10, and by embedding SiO x The element separation portion 15 is formed by forming a film. Next, a trench 12H having a bottom located in the p-well 12 is formed from the surface 10S1 side at a predetermined position of the semiconductor substrate 10. Subsequently, an oxide film is formed by bottom-up film formation using an inhibitor or a sputtering method, for example, so that the bottom of the trench 12H is thicker than its sidewall. Thereafter, as Figure 6C As shown, the oxide film of the trench 12H is removed by wet processing using a chemical solution such as DHF to form an oxide film 18 at the bottom of the trench 12H.

[0169] Next, if Fig.6D As shown in FIG. 1 , Si crystal is grown from the side wall of the trench 12H by an epitaxial crystal growth method to fill the trench 12H. Fig. 6E As shown, the surface 10S1 of the semiconductor substrate 10 and the SiO2 layer formed on the surface 10S1 of the semiconductor substrate 10 are polished by, for example, chemical mechanical polishing (CMP). x film to flatten the surface. Fig. 6F As shown, for example, n-type impurities are implanted by ion implantation to form the FD 19 over the oxide film 18. Next, a multilayer wiring layer 30 including pixel transistors is formed on the surface 10S1 of the semiconductor substrate 10 using a FEOL step.

[0170] Next, if Figure 6G As shown, the trench 10H constituting the separation portions 16 and 17 is formed from the surface 10S2 side of the semiconductor substrate 10 using photolithography and etching. At this time, the etching of the trench 10H constituting the separation portion 17 is stopped at the oxide film 18 formed in the p-well 12.

[0171] Then, a pinning film is formed on the inner wall and bottom surface of the trench 10H using, for example, an atomic layer deposition (ALD) method. Next, an insulating film is embedded in the trench 10H using, for example, an ALD method. Then, the insulating film and the pinning film formed on the surface 10S2 of the semiconductor substrate 10 are polished using, for example, CMP to flatten the surface. Figure 6H As shown, thereby allowing the separation sections 16 and 17 to be formed. Thereafter, a light shielding film 41 is formed on the separation section 16, and then a color filter 42 and an on-chip lens 43 are formed. As described above, the Figure 1 The light detector 1 is shown.

[0172] [Function and Effect]

[0173] In the photodetector 1 according to the present embodiment, a plurality of unit pixels P are arranged in a matrix. In a semiconductor substrate 10 in which FD 19 is provided on a surface 10S1 between a plurality of unit pixels P adjacent to each other, a separation portion 16 penetrating from the surface 10S1 of the semiconductor substrate 10 to the surface 10S is provided around the outer periphery of a unit cell U including a plurality of unit pixels P sharing the FD 19. A separation portion 17 having a bottom located in the semiconductor substrate 10 and extending from the surface 10S2 of the semiconductor substrate 10 toward the surface 10S1 thereof is provided between adjacent unit pixels P constituting the unit cell U and above the FD 19. An oxide film 18 having a larger width than the bottom of the separation portion 17 is provided at the bottom of the separation portion 17. Thus, dispersion of the distance between the FD 19 and the bottom of the separation portion 17 is reduced. This will be described below.

[0174] In recent years, in order to realize fine pixels, a structure has been envisioned in which pixel transistors are manufactured on the front surface side of a semiconductor substrate. To realize this structure, it is necessary to separately manufacture a reverse full trench isolation (RFTI: Reverse Full Trench Isolation) and a reverse deep trench isolation (RDTI: Reverse Deep Trench Isolation).

[0175] Photodetectors with a typical structure require that the dry etching process be stopped midway from the back side of the semiconductor substrate when forming the RDTI; variations in trench depth are a problem.

[0176] In contrast, in the present embodiment, the oxide film 18 is formed in advance at the bottom of the separation portion 17 having the DTI structure formed over the FD 19 , and is allowed to function as an etching stopper film when processing the DTI (trench 10H).

[0177] As described above, in the photodetector 1 according to the present embodiment, the dispersion of the distance between the separator 17 and the FD 19 is reduced, so that the performance thereof can be improved.

[0178] Furthermore, in the present embodiment, the oxide film 18 functions as an etching stopper film when processing the DTI (trench 10H), so that the FTI constituting the separation portion 16 and the DTI constituting the separation portion 17 can be formed together.

[0179] Furthermore, in a photodetector having a typical structure, the following problem is conceivable: due to film formation of a p-type layer from the back side of a semiconductor substrate, the bottom of the RDTI may be pinned to the p-type, thereby enhancing the electric field relative to the n-type FD and reducing the dark time characteristics.

[0180] In contrast, in the photodetector 1 according to the present embodiment, by forming the oxide film 18 at the bottom of the separation portion 17, the pinning of holes by the pinning film 17H above the FD 19 is relaxed. Thus, the electric field with respect to the n-type FD 19 is relaxed, thereby reducing the dark current of the FD 19. That is, the performance of the photodetector 1 can be further improved.

[0181] Next, the second to sixth embodiments of the present invention and Modifications 1 to 8 will be described. Hereinafter, components similar to those of the aforementioned first embodiment are denoted by the same reference numerals, and description thereof is appropriately omitted.

[0182] <2. Modification 1>

[0183] Figure 7 An example of a cross-sectional configuration of a photodetector (photodetector 1A) according to variant 1 of the present invention is schematically shown. In the same manner as in the aforementioned first embodiment, the photodetector 1A is, for example, a CMOS image sensor used in an electronic device such as a digital still camera or a video camera, and is, for example, a back-illuminated photodetector.

[0184] like Figure 7 As shown, a p-type diffusion region 22 may be further provided on the outer wall of the separation portions 16 and 17. For example, the p-type diffusion region 22 may be formed by plasma doping or solid phase after the trenches 10H constituting the separation portions 16 and 17 are formed.

[0185] As described above, by providing the p-type diffusion region 22 on the outer walls of the separation portions 16 and 17, a strong electric field region is allowed to be formed in the pn junction region between the n-type diffusion region 14 and the p-type diffusion region 22, thereby retaining the charge generated in the PD 11. Thus, it is possible to simultaneously achieve an increase in saturation charge capacity and a reduction in dark current.

[0186] <3. Second embodiment>

[0187] Figure 8 An example of a cross-sectional configuration of a light detector (light detector 2) according to a second embodiment of the present invention is schematically shown. In the same manner as in the aforementioned first embodiment, the light detector 2 is, for example, a CMOS image sensor used in an electronic device such as a digital still camera or a video camera, and is, for example, a back-illuminated light detector.

[0188] In the photodetector 2 according to the present embodiment, a plurality of unit pixels P are arranged in a matrix. In addition, in a semiconductor substrate 10 in which FD 19 is provided on a surface (surface 10S1) between a plurality of unit pixels P adjacent to each other, a separation portion 16 is provided around the outer periphery of the plurality of unit pixels P sharing the FD 19. The separation portion 16 penetrates a pair of surfaces (surface 10S1 and surface 10S2) of the semiconductor substrate 10 that are opposite to each other. A separation portion 17 is provided above the FD 19. The separation portion 17 extends from the surface 10S2 of the semiconductor substrate 10 toward the surface 10S1 thereof, and has a bottom portion located in the semiconductor substrate 10. An etching inhibition layer 23 is also provided at the bottom of the separation portion 17.

[0189] The etching inhibiting layer 23 corresponds to a specific example of the “oxide film” of the present invention, and is provided in contact with the bottom of the separation portion 17 formed at the interface or inside the p-well 12. When processing the trench (DTI) constituting the separation portion 17, the etching inhibiting layer 23 serves as an etching stopper film, and reduces the dispersion of the distance between the separation portion 17 and the FD 19. For example, Figure 8 As shown, the etching inhibiting layer 23 is provided to have a larger width in the XZ plane direction than the separation portion 17 .

[0190] The etching inhibiting layer 23 can be formed by, for example, heat treatment and ion implantation of carbon (C), oxygen (O), nitrogen (N), etc. from the surface 10S1 of the semiconductor substrate 10. That is, the etching inhibiting layer 23 includes, for example, silicon carbide (SiC), silicon oxide (SiO x ) or silicon nitride (SiN x ).

[0191] In this way, in the present embodiment, by pre-forming the etching inhibition layer 23 at the bottom of the separation portion 17 having the DTI structure formed above the FD19, it is possible to jointly form grooves with different depths in one groove processing, that is, jointly form the FTI constituting the separation portion 16 and the DTI constituting the separation portion 17.

[0192] As described above, in the photodetector 2 according to the present embodiment, the characteristic fluctuation caused by the misalignment between the separation portion 16 and the separation portion 17 is reduced. In addition, the dispersion of the distance between the separation portion 17 and the FD 19 can be reduced to the dispersion level of ion implantation. Thus, its performance as a photodetector can be improved.

[0193] <4. Modification 2>

[0194] Fig. 9 An example of a planar structure of a light detector (light detector 2A) according to variant 2 of the present invention is schematically shown. The light detector 2A is, for example, a CMOS image sensor used in an electronic device such as a digital still camera or a video camera, and is, for example, a back-illuminated light detector capable of simultaneously acquiring imaging information and parallax information.

[0195] The etching inhibiting layer 23 described in the foregoing second embodiment may also be formed in a region different from the region above the FD 19. For example, Fig. 9 As shown, the separation portion 17 having the DTI structure may be provided as a blooming path between two PDs 11 provided in one unit pixel P, and the etching inhibition layer 23 may be provided at the bottom of the separation portion 17 .

[0196] <5. Modification 3>

[0197] Fig.10 An example of a cross-sectional configuration of a photodetector (photodetector 2B) according to variant 3 of the present invention is schematically shown. The photodetector 2B is, for example, a CMOS image sensor used in an electronic device such as a digital still camera or a video camera, and is, for example, a back-illuminated photodetector of a so-called global shutter system.

[0198] A global shutter system is a system that performs global exposure, which starts exposure of all pixels substantially at the same time and completes exposure of all pixels at the same time. As used herein, all pixels refer to all pixels of a portion that appears in an image, and do not include dummy pixels, etc. In addition, a global shutter system also includes a system that moves the area where global exposure is performed while performing global exposure in units of multiple rows (e.g., dozens of rows) rather than in units of all pixels at the same time when the time difference or image distortion is small enough not to cause a problem. In addition, a global shutter system also includes a system that performs global exposure on pixels of a predetermined area rather than all pixels of a portion that appears in an image.

[0199] The photodetector 2B implements a memory holding global shutter, and the unit pixel P includes a charge accumulation section (MEM 27) that temporarily holds the charge generated in the PD 11 until the charge is transferred to the FD 19. Fig.10 As shown, the MEM 27 is formed to be embedded on the surface 10S1 side of the semiconductor substrate 10. The separation portion 17 having the DTI structure is provided between the PD 11 and the MEM 27, and the light shielding film 41 is formed to extend on the surface 10S2 of the semiconductor substrate 10 provided with the MEM 27. The etching inhibition layer 23 described in the aforementioned second embodiment may be provided at the bottom of the separation portion 17 located between the PD 11 and the MEM 27.

[0200] <6. Third embodiment>

[0201] Fig.11 An example of a cross-sectional configuration of a light detector (light detector 3) according to a third embodiment of the present invention is schematically shown. In the same manner as in the aforementioned first embodiment, the light detector 3 is, for example, a CMOS image sensor used in an electronic device such as a digital still camera or a video camera, and is, for example, a back-illuminated light detector.

[0202] In the photodetector 3 according to the present embodiment, a plurality of unit pixels P are arranged in a matrix. In addition, in a semiconductor substrate 10 in which FD 19 is provided on a surface (surface 10S1) between a plurality of unit pixels P adjacent to each other, a separation portion 16 is provided around the outer periphery of a plurality of unit pixels P sharing FD 19. The separation portion 16 penetrates a pair of surfaces (surface 10S1 and surface 10S2) of the semiconductor substrate 10 that are opposite to each other. A separation portion 17 is provided above FD 19. The separation portion 17 extends from the surface 10S2 of the semiconductor substrate 10 toward the surface 10S1 thereof, and has a bottom located in the semiconductor substrate 10. A pinning film 24 having a weaker pinning force than a pinning film 17A formed on the inner wall of the separation portion 17 is exposed to the bottom of the separation portion 17.

[0203] The pinning film 24 corresponds to a specific embodiment of the "second pinning film" of the present invention. Fig.11 As shown, the pinning film 24 extends on the surface 10S2 of the semiconductor substrate 10, and is formed on the inner wall of the groove 10H constituting the separation parts 16 and 17 via the pinning films 16A and 17A. In addition, at the bottom of the separation parts 16 and 17, the pinning films 16A and 17A are removed, resulting in the pinning film 24 being exposed. As described above, examples of usable constituent materials of the pinning film 24 include materials having a weaker pinning force than the pinning film 17A; examples of such materials include hafnium oxide (HfO x ).

[0204] The separation portions 16 and 17 according to the present embodiment can be formed, for example, as follows.

[0205] First, as in the aforementioned first embodiment, the grooves 10H constituting the separation portions 16 and 17 are formed from the surface 10S2 side of the semiconductor substrate 10. Thereafter, for example, Fig. 12A As shown in FIG. 1 , an aluminum oxide film serving as the pinning films 16A and 17A is formed on the inner wall and bottom surface of the trench 10H by using the ALD method. Fig. 12B As shown, the aluminum oxide film formed on the surface 10S2 of the semiconductor substrate 10 and on the bottom surface of the trench 10H is removed by etch back. This allows the pinning films 16A and 17A to be formed on the respective side surfaces of the trench 10H constituting the separation portions 16 and 17.

[0206] Then, if Fig. 12C As shown, for example, a hafnium oxide film serving as the pinning film 24 is formed on the sidewalls and bottom surfaces of each trench 10H having the side surfaces formed with the pinning films 16A and 17A using the ALD method. Next, although not shown, an antireflection film or the like is formed, and then, as shown in FIG. Fig.12D As shown, an insulating film is embedded in the trench 10H using, for example, the ALD method. Thereafter, for example, the insulating film formed on the surface 10S2 of the semiconductor substrate 10 is polished by CMP to flatten the surface. This allows the formation of Fig.11 Separation sections 16 and 17 are shown.

[0207] As described above, in the present embodiment, the pinning film 17A formed at the bottom of the separation portion 17 having the DTI structure formed above the FD 19 is removed, and the pinning film 24 having a weaker pinning force than the pinning film 17A is formed on the inner wall of the separation portion 17. Thus, the pinning film 24 is allowed to be exposed to the bottom of the separation portion 17, thereby relaxing the electric field with respect to the n-type FD 19 while suppressing the interface state.

[0208] As described above, in the photodetector 3 according to the present embodiment, the dark current of the FD 19 can be reduced, so that the performance thereof can be improved.

[0209] <7. Modification 4>

[0210] Fig.13 An example of a cross-sectional configuration of a light detector (light detector 3A) according to variant 4 of the present invention is schematically shown. In the same manner as in the aforementioned first embodiment, the light detector 3A is, for example, a CMOS image sensor used in an electronic device such as a digital still camera or a video camera, and is, for example, a back-illuminated light detector.

[0211] The third embodiment described above illustrates that the pinning film 24 having a weaker pinning force than the pinning film 17A is exposed at the bottom of the separation portion 17; however, the bottom of the separation portion 17 may not have a pinning force. Specifically, a structure that allows the insulating film 17B to be exposed at the bottom of the separation portion 17 may be adopted.

[0212] The separation parts 16 and 17 of this modification can be formed, for example, as follows.

[0213] First, in the same manner as in the aforementioned third embodiment, an aluminum oxide film serving as the pinning films 16A and 17A is formed on the inner wall and bottom surface of the trench 10H using, for example, the ALD method. Fig.14A As shown, the aluminum oxide film formed on the surface 10S2 of the semiconductor substrate 10 and on the bottom surface of the trench 10H is removed by etching back, thereby forming pinning films 16A and 17A on the respective side surfaces of the trench 10H constituting the separation portions 16 and 17 .

[0214] like Fig. 14B As shown, the pinning film 24 is formed on the surface 10S2 of the semiconductor substrate 10 using, for example, a sputtering method. Next, although not shown, an antireflection film or the like is formed, and then, as shown in FIG. Fig. 14C As shown, an insulating film is embedded in the trench 10H using, for example, the ALD method. Thereafter, for example, the insulating film formed on the surface 10S2 of the semiconductor substrate 10 is polished by CMP to flatten the surface. Thus, the formation of Fig.13 Separation sections 16 and 17 are shown.

[0215] As described above, in the present modification, the pinning film 17A formed at the bottom of the separation portion 17 having the DTI structure formed above the FD 19 is removed, and the insulating film 17B is exposed to the bottom of the separation portion 17, so that the bottom of the separation portion 17 has no pinning force. Thus, the electric field with respect to the n-type FD 19 is relaxed in the same manner as in the aforementioned third embodiment.

[0216] As described above, in the photodetector 3A according to the present modification, the dark current of the FD 19 can be reduced in the same manner as in the aforementioned third embodiment, so that the performance thereof can be improved.

[0217] <8. Fourth embodiment>

[0218] Fig.15 An example of a cross-sectional configuration of a light detector (light detector 4) according to a fourth embodiment of the present invention is schematically shown. In the same manner as in the aforementioned first embodiment, the light detector 4 is, for example, a CMOS image sensor used in an electronic device such as a digital still camera or a video camera, and is, for example, a back-illuminated light detector.

[0219] In the photodetector 4 according to the present embodiment, a plurality of unit pixels P are arranged in a matrix. In addition, in a semiconductor substrate 10 in which FD 19 is provided on a surface (surface 10S1) between a plurality of unit pixels P adjacent to each other, a separation portion 16 is provided around the outer periphery of a plurality of unit pixels P sharing FD 19. The separation portion 16 penetrates a pair of surfaces (surface 10S1 and surface 10S2) of the semiconductor substrate 10 that are opposite to each other. The separation portion 17 is provided between adjacent unit pixels P sharing FD 19, but is not provided in a region above FD 19. The separation portion 17 extends from the surface 10S2 of the semiconductor substrate 10 toward the surface 10S1 thereof, and has a bottom portion located in the semiconductor substrate 10. The separation portion 25 is provided above FD 19. The separation portion 25 extends from the surface 10S2 of the semiconductor substrate 10 toward the surface 10S1 thereof, and has a bottom portion located in the semiconductor substrate 10. A pinning film 25A having a weaker pinning force than the pinning films formed on the inner walls of the separation portions 16 and 17 is formed on the inner wall of the separation portion 25 .

[0220] The separation portion 25 corresponds to a specific example of the "second groove portion" of the present invention. The separation portion 25 is composed of, for example, a pinning film 25A and an insulating film 25B. The pinning film 25A is provided on the inner wall and bottom surface of the groove (DTI) forming the separation portion 25 and has a positive fixed charge. The insulating film 25B fills the groove.

[0221] As described above, examples of usable constituent materials of the pinning film 25A include materials having a weaker pinning force than the pinning films 16A and 17A. Examples of such materials include hafnium oxide (HfO x ), lanthanum oxide (LaO x ) and yttrium oxide (YO x ). The pinning film 25A may be a single-layer film or a stacked film including different materials. The pinning film 25A corresponds to a specific example of the "second pinning film" of the present invention.

[0222] Examples of the constituent material of the insulating film 25B include silicon oxide (SiO x ), silicon nitride (SiN x ) and polysilicon (Poly-Si).

[0223] In addition, a conductive film having a light-shielding property can be embedded in the pinning film 25A. Specific examples thereof include tungsten (W), silver (Ag), copper (Cu), aluminum (Al), and alloys of Al and Cu. The conductive film can be a single-layer film, or a stacked film containing different materials. Examples of stacked films include stacked films of Al and cobalt (Co) or stacked films of Al and Ti that constitute so-called barrier metals. As described above, by embedding a conductive film having a light-shielding property in the pinning film 25A, adjacent unit pixels P in the unit unit U can be electrically and optically separated from each other.

[0224] The separation portions 16 , 17 , and 25 according to the present embodiment can be formed, for example, as follows.

[0225] First, as in the first embodiment described above, Fig.16A and 17A As shown, a multilayer wiring layer 30 including pixel transistors is formed on the surface 10S1 of the semiconductor substrate 10 using the FEOL step, and then a trench 10H1 is formed over the FD 10. Next, as Fig. 16B and 17B As shown in FIG. 1 , a pinning film 25A and an insulating film 25B are formed in the trench 10H1 . This allows the separation portion 25 to be formed above the FD 19 .

[0226] Then, if Fig. 17C As shown, FTI (trench 10H2) is formed around the outer periphery of the unit cell U, and as shown in FIG. Fig.17D As shown in FIG. 1 , a DTI (groove 10H3) is formed between adjacent unit pixels P in the unit cell U. Thereafter, as shown in FIG. Fig. 16C As shown, the pinning films 16A and 17A and the insulating films 16B and 17B are formed in the trenches 10H2 and 10H3. Thus, the separation portions 16 and 17 are allowed to be formed.

[0227] In recent years, in order to realize fine pixels, an imaging device has been developed in which four pixels that share FD and are arranged in two rows and two columns are separated by RDTI, and the outer periphery of the four pixels that share FD is separated by RFTI. As for concerns about this structure, RDTI and FD need to have a certain distance from each other (500nm to 600nm depending on certain conditions), and precise processing is required.

[0228] However, it has been found that by processing RDTI to have a grid pattern, only the intersection portion needs to be deeply processed. In addition, by forming a typical pinning film on the inner wall of RDTI, the electric field directly above the FD may become strong, thereby deteriorating the characteristics.

[0229] In contrast, in the present embodiment, for example, a cylindrical DTI (groove 10H1) is formed in advance above the FD 19, and a pinning film 25A including a pinning material having a weaker pinning force than that formed on the inner walls of the separation portions 16 and 17 is formed on the inner wall thereof.

[0230] As described above, in the photodetector 3 according to the present embodiment, the distance between the separator 25 and the FD 19 is secured and the dispersion of the distance between the separator 25 and the FD 19 is reduced. In addition, the pinning force just above the FD 19 is reduced, so that the performance thereof can be improved.

[0231] <9. Modification 5>

[0232] 17 schematically shows an example of a planar configuration of a light detector (light detector 4A) according to variant 5 of the present invention. In the same manner as in the aforementioned first embodiment, the light detector 4A is, for example, a CMOS image sensor used in an electronic device such as a digital still camera or a video camera, and is, for example, a back-illuminated light detector.

[0233] The aforementioned fourth embodiment exemplifies the formation of a cylindrical DTI, for example, used as the separation portion 25 above the FD 19; however, the shape of the DTI used as the separation portion 25 is not limited thereto. For example, the planar shape of the separation portion 25 may be as follows: Fig.18 The cross shape shown, or may be a polygon such as a quadrilateral, although no illustration thereof is given. In addition, the separation section 16 having an FTI structure disposed between mutually adjacent unit cells U may extend between a plurality of unit pixels P sharing the FD 19 to allow the separation section 16 and the separation section 25 to contact each other.

[0234] In this configuration as well, effects similar to those of the aforementioned fourth embodiment can be obtained.

[0235] <10. Fifth embodiment>

[0236] Fig.19 A cross-sectional configuration example of a photodetector (photodetector 5 ) according to a fifth embodiment of the present invention is schematically shown. Fig. 20A and 20B Schematically shown respectively Fig.19The illustrated planar configuration example of the photodetector 5. In the same manner as the aforementioned first embodiment, the photodetector 5 is, for example, a CMOS image sensor or the like used in electronic equipment such as a digital still camera or a video camera, and is, for example, a back-illuminated photodetector.

[0237] In the photodetector 5 according to the present embodiment, a plurality of unit pixels P are arranged in a matrix. In addition, in the semiconductor substrate 10 in which the FD 19 is provided on the surface (surface 10S1) between the plurality of unit pixels P adjacent to each other, the separation parts 51 and 52 each having a DTI structure are provided, for example, around the outer periphery of the plurality of unit pixels P sharing the FD 19 and between the adjacent unit pixels P sharing the FD 19. The element separation part 53 is provided at each bottom of the separation parts 51 and 52. The width of the element separation part 53 on the bottom side of the separation parts 51 and 52 is greater than the width on the surface 10S1 side of the semiconductor substrate 10.

[0238] The separation portion 51 corresponds to the "first separation portion" of the present invention, and is provided between the unit cells U adjacent to each other as described above. In other words, the separation portion 51 is provided to surround the outer periphery of four unit pixels that share the FD 19 and are arranged in two rows and two columns, for example, and is provided in a grid pattern in the pixel portion 100A. The separation portion 51 electrically separates the adjacent unit cells U from each other. For example, the separation portion 51 extends from the surface 10S2 side of the semiconductor substrate 10 toward the surface 10S1 side thereof, and constitutes a DTI structure having a bottom located in the semiconductor substrate 10, specifically, having a bottom at the interface or inside the p-well 12.

[0239] The separation portion 51 is composed of, for example, a pinning film 51A and an insulating film 51B. The pinning film 51A is provided on the inner wall and bottom surface of the groove forming the separation portion 51 and has positive fixed charge. The insulating film 51B fills the groove.

[0240] Examples of the constituent material of the pinning film 51A include hafnium oxide (HfO x ), aluminum oxide (AlO x )、ZrO x ), tantalum oxide (TaO x ), titanium oxide (TiO x ), lanthanum oxide (LaO x ), praseodymium oxide (PrO x ), cerium oxide (CeO x ), neodymium oxide (NdO x ), promethium oxide (PmO x ), samarium oxide (SmO x ), europium oxide (EuO x ), Gadolinium oxide (GdO x), terbium oxide (TbO x ), Dysprosium oxide (DyO x ), holmium oxide (HoO x ), thulium oxide (TmO x ), Ytterbium oxide (YbO x ), Lutetium oxide (LuO x ), yttrium oxide (YO x ), Hafnium Nitride (HfN x ), aluminum nitride (AlN x ), Hafnium Oxynitride (HfO x N y ) and aluminum oxynitride (AlO x N y ). The pinning film 51A may be a single-layer film, or a stacked film including different materials.

[0241] Examples of the constituent material of the insulating film 51B include silicon oxide (SiO x )membrane.

[0242] In addition, a conductive film having light-shielding properties may be embedded in the pinning film 51A of the groove forming the separation portion 51. Specific examples thereof include tungsten (W), silver (Ag), copper (Cu), aluminum (Al), and alloys of Al and Cu. The conductive film may be a single-layer film or a stacked film containing different materials. Examples of stacked films include stacked films of Al and cobalt (Co) or stacked films of Al and Ti constituting so-called barrier metals. As described above, by embedding a conductive film having light-shielding properties in the pinning film 51A, adjacent unit cells U can be electrically and optically separated from each other.

[0243] The separation portion 52 corresponds to the "first separation portion" of the present invention. As described above, for example, the separation portion 52 is provided between a plurality of unit pixels P that share the FD 19, and contacts the separation portion 51 on the outer periphery of the unit cell U. In addition to the above, the separation portion 52 may be selectively provided only above the FD 19 located near the intersection of four unit pixels that constitute the unit cell U and are arranged, for example, in two rows and two columns. At this time, the separation portion 51 extends from the outer periphery of the unit cell U toward the separation portion 52 between the adjacent unit pixels P that constitute the unit cell U, and contacts the separation portion 52 near the FD 19 in a plan view. The separation portion 52 electrically separates the adjacent unit pixels P in the unit cell U from each other, and, for example, extends from the surface 10S2 side of the semiconductor substrate 10 toward the surface 10S1 side thereof; the separation portion 52 has a DTI structure having a bottom located in the semiconductor substrate 10, specifically, having a bottom at the interface or inside the p-well 12.

[0244] The separation portion 52 is composed of, for example, a pinning film 52A and an insulating film 52B in the same manner as the separation portion 51. The pinning film 52A is provided on the inner wall and bottom surface of the groove forming the separation portion 52 and has positive fixed charge. The insulating film 52B fills the groove.

[0245] Examples of the constituent material of the pinning film 52A include hafnium oxide (HfO x ), aluminum oxide (AlO x )、ZrO x ), tantalum oxide (TaO x ), titanium oxide (TiO x ), lanthanum oxide (LaO x ), praseodymium oxide (PrO x ), cerium oxide (CeO x ), neodymium oxide (NdO x ), promethium oxide (PmO x ), samarium oxide (SmO x ), europium oxide (EuO x ), Gadolinium oxide (GdO x ), terbium oxide (TbO x ), Dysprosium oxide (DyO x ), holmium oxide (HoO x ), thulium oxide (TmO x ), Ytterbium oxide (YbO x ), Lutetium oxide (LuO x ), yttrium oxide (YO x ), Hafnium Nitride (HfN x ), aluminum nitride (AlN x ), Hafnium Oxynitride (HfO x N y ) and aluminum oxynitride (AlO x N y ). The pinning film 52A may be a single-layer film, or a stacked film including different materials.

[0246] Examples of the constituent material of the insulating film 52B include silicon oxide (SiO x ).

[0247] In addition, a conductive film having light-shielding properties may be embedded in the pinning film 52A of the groove forming the separation portion 52. Specific examples thereof include tungsten (W), silver (Ag), copper (Cu), aluminum (Al), and alloys of Al and Cu. The conductive film may be a single-layer film, or a stacked film containing different materials. Examples of stacked films include stacked films of Al and cobalt (Co) or stacked films of Al and Ti constituting so-called barrier metals. As described above, by embedding a conductive film having light-shielding properties in the pinning film 52A, adjacent unit pixels P in the unit unit U may be electrically and optically separated from each other.

[0248] The element separation portion 53 corresponds to a specific example of the "second separation portion" of the present invention. The element separation portion 53 separates the pixel transistors and the like from each other on the surface 10S1 side of the semiconductor substrate 10, and has an STI structure. As described above, the element separation portion 53 is provided at the bottom of each of the separation portions 51 and 52. As described above, the cross-sectional shape of the element separation portion 53 on the bottom side of the separation portions 51 and 52 is wider than the cross-sectional shape on the surface 10S1 side of the semiconductor substrate 10.

[0249] Specifically, the element separation portion 53 has, for example, a T-shaped cross-sectional shape, and includes a vertical portion 53A and a horizontal portion 53B. For example, the width of the horizontal portion 53B is greater than the width of each of the separation portions 51 and 52. The vertical portion 53A may be formed as follows. Fig. 20A As shown, the bottom of the separation parts 51 and 52 can be continuously arranged in a grid pattern, or it can be as shown in FIG. Fig. 20B In addition, the cross-sectional shape of the element separation portion 53 is not limited thereto, and for example, Fig.21 As shown, it can be roughly trapezoidal in shape.

[0250] The element separation portion 53 is made of, for example, silicon oxide (SiO x ) film is formed. In addition to the above, in the element separation portion 53, a silicon oxide film may be formed on the inner wall thereof, and a silicon nitride film may be embedded therein. Alternatively, in the element separation portion 53, a silicon oxide film may be formed on the inner wall thereof, and polysilicon may be further embedded therein.

[0251] Note that in the present embodiment, for each unit pixel P, the FDs 19 are separated from each other by the element separation section 53 , and the FDs 19 are electrically connected to each other by the contact layer 36 provided on the surface 10S1 of the semiconductor substrate 10 .

[0252] The element separation portion 53 can be formed, for example, as follows.

[0253] First, if Fig.22A As shown in FIG. 1 , a trench 12H1 serving as the vertical portion 53A is formed in the p-well 12 from the surface 10S1 side of the semiconductor substrate 10. Fig. 22B As shown, the side surface of the trench 12H1 is protected by the protective film 54. Fig. 22C As shown, the trench 12H2 used as the horizontal portion 53B is formed by wet etching. At this time, when the silicon substrate having a (111) plane orientation is etched using an alkaline etchant, the planar shape of the trench 12H2 is as follows: Fig.23A The rectangular shape shown in FIG. Fig. 23B The shape shown (corresponding to Fig.23A Line II-II) and Fig.23C The shape shown (corresponding to Fig.23A In addition, as in Fig.23D In the embodiment, as to the cross-sectional shape of the trench 12H2, the silicon substrate having a (100) plane orientation is etched.

[0254] Then, if Fig.22D As shown, the protective film 54 is removed, and then, for example, as Fig.22E As shown, a silicon oxide film is embedded in the trenches 12H1 and 12H2. This allows the element separation portion 53 having a T-shape to be formed.

[0255] As described above, in the present embodiment, the element separation portion 53 that allows pixel transistors and the like to be separated from each other on the surface 10S1 side of the semiconductor substrate 10 has a wider shape on the surface 10S2 side of the semiconductor substrate 10 than on the surface 10S1 side. Thus, the element formation area on the surface 10S1 side of the semiconductor substrate 10 can be ensured.

[0256] As described above, in the photodetector 5 according to the present embodiment, the area efficiency of the elements formed on the surface 10S1 of the semiconductor substrate 10 can be improved, thereby reducing the pixel size. Thus, the performance as a photodetector can be improved.

[0257] <11. Modification 6>

[0258] Fig.24 An example of a planar structure of a light detector (light detector 5A) according to variant example 6 of the present invention is schematically shown. In the same manner as in the aforementioned first embodiment, the light detector 5A is, for example, a CMOS image sensor used in an electronic device such as a digital still camera or a video camera, and is, for example, a back-illuminated light detector.

[0259] The foregoing fifth embodiment illustrates an example in which the separation section 51 around the outer periphery of four unit pixels arranged in two rows and two columns and surrounding the common FD 19 is allowed to have a DTI structure and have an FTI structure together with the element separation section 53. However, this is not restrictive. Fig.24 As shown, the separation portion 51 may be a structure that penetrates the semiconductor substrate 10 itself.

[0260] <12. Modification 7>

[0261] Fig.25 An example of a planar configuration of a photodetector (photodetector 5B) according to Modification 7 of the present invention is schematically shown. Fig.26 Show Fig.25 The planar configuration example of the photodetector 5B shown in FIG. Fig.25 Corresponds to Fig.26Line IV-IV is shown. In the same manner as the aforementioned first embodiment, the photodetector 5B is, for example, a CMOS image sensor or the like used in electronic equipment such as a digital still camera or a video camera, and is, for example, a back-side illumination type photodetector.

[0262] For example, Fig.26 As shown, pixel transistors constituting the readout circuit (e.g., reset transistor RST, selection transistor SEL, and amplifier transistor AMP) may be disposed around a unit cell U of a plurality of unit pixels P including a common FD 19. Alternatively, the pixel transistors may be disposed in another substrate stacked on the surface 10S1 side and electrically connected to the semiconductor substrate 10. Fig.26 As shown, in the case where the pixel transistor is formed around the unit cell U, the element separation portion 15 of the aforementioned first embodiment and the like may be formed between the unit cell U and the pixel transistor.

[0263] <13. Sixth Embodiment>

[0264] Fig.33 A cross-sectional configuration example of a photodetector (photodetector 6 ) according to a sixth embodiment of the present invention is schematically shown. Fig.34 is the photodetector 6 and Fig.33 A schematic diagram of an example of a plane configuration corresponding to line AA shown. Fig.35 is the photodetector 6 and Fig.33 A schematic diagram of an example of a plane configuration corresponding to line BB shown. Fig.36A is the photodetector 6 and Fig.33 A schematic diagram of an example of a plane configuration corresponding to line CC shown. Fig.36B is the photodetector 6 and Fig.33 Schematic diagram of another planar configuration example corresponding to line CC shown. In the same manner as the aforementioned first embodiment, the photodetector 6 is, for example, a CMOS image sensor used in electronic equipment such as a digital still camera or a video camera, and is, for example, a back-illuminated photodetector.

[0265] In the photodetector 6 according to the present embodiment, a plurality of unit pixels P are arranged in a matrix. In addition, in the semiconductor substrate 10 in which the FD 19 is provided on the surface (surface 10S1) between the plurality of unit pixels P adjacent to each other, the separation parts 51 and 52 each having a DTI structure are provided, for example, around the outer periphery of the plurality of unit pixels P sharing the FD 19 and between the adjacent unit pixels P sharing the FD 19. The element separation part 63 is provided at each bottom of the separation parts 51 and 52. The width of the element separation part 63 on the bottom side of the separation parts 51 and 52 is greater than the width on the surface 10S1 side of the semiconductor substrate 10. The element separation part 63 has, for example, an inclined side surface.

[0266] The separation portion 51 corresponds to the "first separation portion" of the present invention, and is provided between the unit cells U adjacent to each other as described above. In other words, the separation portion 51 is provided to surround the outer periphery of four unit pixels that share the FDs 19A, 19B, 19C, and 19D and are arranged, for example, in two rows and two columns, and is provided in a grid pattern in the pixel portion 100A. The separation portion 51 electrically separates the adjacent unit cells U from each other. For example, the separation portion 51 extends from the surface 10S2 side of the semiconductor substrate 10 toward the surface 10S1 side thereof, and constitutes a DTI structure having a bottom located in the semiconductor substrate 10, specifically, having a bottom at the interface or inside the p-well 12.

[0267] The separation portion 51 is composed of, for example, a pinning film 51A and an insulating film 51B. The pinning film 51A is provided on the inner wall and bottom surface of the groove forming the separation portion 51 and has positive fixed charge. The insulating film 51B fills the groove.

[0268] Examples of the constituent material of the pinning film 51A include hafnium oxide (HfO x ), aluminum oxide (AlO x )、ZrO x ), tantalum oxide (TaO x ), titanium oxide (TiO x ), lanthanum oxide (LaO x ), praseodymium oxide (PrO x ), cerium oxide (CeO x ), neodymium oxide (NdO x ), promethium oxide (PmO x ), samarium oxide (SmO x ), europium oxide (EuO x ), Gadolinium oxide (GdO x ), terbium oxide (TbO x ), Dysprosium oxide (DyO x ), holmium oxide (HoO x ), thulium oxide (TmO x ), Ytterbium oxide (YbO x ), Lutetium oxide (LuO x ), yttrium oxide (YO x ), Hafnium Nitride (HfN x ), aluminum nitride (AlN x ), Hafnium Oxynitride (HfO x N y ) and aluminum oxynitride (AlO x N y ). The pinning film 51A may be a single-layer film, or a stacked film including different materials.

[0269] Examples of the constituent material of the insulating film 51B include silicon oxide (SiO x )membrane.

[0270] In addition, a conductive film having a light-shielding property may be embedded in the pinning film 51A of the groove forming the separation portion 51. Specific examples thereof include tungsten (W), silver (Ag), copper (Cu), aluminum (Al), and alloys of Al and Cu. The conductive film may be a single-layer film, or a stacked film containing different materials. Examples of stacked films include a stacked film of Al and cobalt (Co) or a stacked film of Al and Ti constituting a so-called barrier metal. As described above, by embedding a conductive film having a light-shielding property in the pinning film 51A, adjacent unit cells U can be electrically and optically separated from each other.

[0271] The separation portion 52 corresponds to the “first separation portion” of the present invention. As described above, for example, the separation portion 52 is provided between a plurality of unit pixels P that share the FD 19, and contacts the separation portion 51 on the outer periphery of the unit cell U. In addition to the above, the separation portion 52 may be selectively provided only above the FD 19 located near the intersection of four unit pixels that constitute the unit cell U and are arranged, for example, in two rows and two columns. At this time, the separation portion 51 extends from the outer periphery of the unit cell U toward the separation portion 52 between the adjacent unit pixels P that constitute the unit cell U, and contacts the separation portion 52 near the FD 19 in a plan view. The separation portion 52 electrically separates the adjacent unit pixels P in the unit cell U from each other, and, for example, extends from the surface 10S2 side of the semiconductor substrate 10 toward the surface 10S1 side thereof; the separation portion 52 has a DTI structure having a bottom located in the semiconductor substrate 10, specifically, having a bottom at the interface or inside the p-well 12.

[0272] The separation portion 52 is composed of, for example, a pinning film 52A and an insulating film 52B in the same manner as the separation portion 51. The pinning film 52A is provided on the inner wall and bottom surface of the groove forming the separation portion 52 and has positive fixed charge. The insulating film 52B fills the groove.

[0273] Examples of the constituent material of the pinning film 52A include hafnium oxide (HfO x ), aluminum oxide (AlO x )、ZrO x ), tantalum oxide (TaO x ), titanium oxide (TiO x ), lanthanum oxide (LaO x ), praseodymium oxide (PrO x ), cerium oxide (CeO x ), neodymium oxide (NdO x ), promethium oxide (PmO x ), samarium oxide (SmO x), europium oxide (EuO x ), Gadolinium oxide (GdO x ), terbium oxide (TbO x ), Dysprosium oxide (DyO x ), holmium oxide (HoO x ), thulium oxide (TmO x ), Ytterbium oxide (YbO x ), Lutetium oxide (LuO x ), yttrium oxide (YO x ), Hafnium Nitride (HfN x ), aluminum nitride (AlN x ), Hafnium Oxynitride (HfO x N y ) and aluminum oxynitride (AlO x N y ). The pinning film 52A may be a single-layer film, or a stacked film including different materials.

[0274] Examples of the constituent material of the insulating film 52B include silicon oxide (SiO x ).

[0275] In addition, a conductive film having light-shielding properties may be embedded in the pinning film 52A of the groove forming the separation portion 52. Specific examples thereof include tungsten (W), silver (Ag), copper (Cu), aluminum (Al), and alloys of Al and Cu. The conductive film may be a single-layer film, or a stacked film containing different materials. Examples of stacked films include stacked films of Al and cobalt (Co) or stacked films of Al and Ti constituting so-called barrier metals. As described above, by embedding a conductive film having light-shielding properties in the pinning film 52A, adjacent unit pixels P in the unit unit U may be electrically and optically separated from each other.

[0276] The element separation portion 63 corresponds to a specific example of the "second separation portion" of the present invention. The element separation portion 63 separates pixel transistors and the like from each other on the surface 10S1 side of the semiconductor substrate 10, and has an STI structure. The element separation portion 63 is provided at the bottom of each separation portion 51 and 52. As described above, the element separation portion 63 is wider on the bottom side of the separation portions 51 and 52 than on the surface 10S1 side of the semiconductor substrate 10. In addition, the element separation portion 63 has a cross-sectional shape with inclined side surfaces. Specifically, the element separation portion 63 has a substantially trapezoidal shape.

[0277] A p-type diffusion region 64 is provided at each side of the separation portions 51 and 52. As for the width of the bottom side of the element separation portion 63, for example, the width of the element separation portion 63 is preferably equal to or larger than the width of the p-type diffusion region 64. Thereby, for example, it is possible to suppress the diffusion of p-type impurities (for example, boron (B)) doped in the p-type diffusion region 64 to the charge transfer path.

[0278] The element separation portion 63 is made of, for example, silicon oxide (SiO x ) film is formed. In addition to the above, in the element separation portion 63, a silicon oxide film may be formed on the inner wall thereof, and a silicon nitride film may be embedded therein. Alternatively, in the element separation portion 63, a silicon oxide film may be formed on the inner wall thereof, and polysilicon may be further embedded therein.

[0279] A gap G may also be formed in the element separation portion 63. For example, Fig.36A As shown in FIG. 1 , the gap G is formed at the intersection of four unit pixels P adjacent to each other in the X-axis direction and the Y-axis direction. Fig.36B As shown, the gap G may be formed to extend between the unit pixels P adjacent to each other in the X-axis direction and the Y-axis direction.

[0280] The element separation portion 63 can be formed, for example, as follows.

[0281] First, if Fig.37A As shown, from the surface 10S1 side of the semiconductor substrate 10 where the silicon nitride film 135 and the silicon oxide film 61 are stacked, a trench 12H3 is formed in the silicon nitride film 135 and the silicon oxide film 61. Fig.37B As shown, the trench 12H3 is extended into the p-well 12 by anisotropic etching.

[0282] Next, an isotropic etch is performed. Fig.37C As shown, the p-well 12 is allowed to be isotropically etched to form a groove 12H3 having, for example, a 45° inclination angle. The inclination angle of the groove 12H3 can be controlled by preparing the etching gas to be used. In addition, in order to be able to suppress the diffusion of the p-type impurities doped in the p-type diffusion region 64 to the charge transfer path as described above, for example, the etching depth can be a depth (for example, 50 nm) that allows the area of ​​the groove 12H3 constituting the element separation portion 63 in the XY plane direction to surround the diffusion length of the p-type impurities doped in the p-type diffusion region 64.

[0283] Then, if Fig.37D As shown, for example, a silicon oxide film 63A including SiO2 / LP-SiN / SiO2 is formed on the sidewall of the trench 12H3. Fig.37E As shown, a trench 12H4 is formed extending from the interior of the trench 12H3 toward the surface 10S2. Fig.37F As shown, boron (B) is diffused laterally in trench 12H4 using, for example, solid phase diffusion or plasma doping to form p-type diffusion region 64 .

[0284] Next, if Figure 37GAs shown in FIG. 1 , a polysilicon film 152 is embedded in the trench 12H4, and then etched back to remove the silicon oxide film 61. Thereafter, as shown in FIG. Fig.37H As shown, a silicon oxide film is embedded in the trench 12H3 using, for example, the ALD method, and then etch-back is performed to remove the silicon oxide film formed on the silicon nitride film 135. Thus, the element separation portion 63 having the gap G is allowed to be formed.

[0285] The element separation portion 63 can be formed, for example, as follows.

[0286] First, using a method similar to that described above, from the surface 10S1 side of the semiconductor substrate 10 where the silicon nitride film 135 and the silicon oxide film 61 are stacked, the trench 12H5 is formed in the silicon nitride film 135 and the silicon oxide film 61. Fig.38A As shown, the trench 12H5 is extended into the p-well 12 by anisotropic etching.

[0287] Next, if Fig.38B As shown, for example, a protective film 62 including SiO2 / LP-SiN / SiO2 is formed on the sidewall of the trench 12H5. Fig.38C As shown, a groove 12H6 is formed extending from the inside of the groove 12H5 toward the surface 10S2. Fig.38D As shown, boron (B) is diffused laterally in the trench 12H6 using, for example, solid phase diffusion or plasma doping to form a p-type diffusion region 64 .

[0288] Then, if Fig.38E As shown, the polysilicon film 152 is embedded in the trench 12H6, and then, as shown in FIG. Fig.38F As shown in FIG. 1 , etching back is performed to remove the protective film 62. Thereafter, as shown in FIG. Figure 38G As shown, isotropic etching is performed to form a groove 12H5 having an inclination angle of, for example, 45°. Thereafter, a silicon oxide film is embedded in the groove 12H3 using, for example, an ALD method, and then etched back to remove the silicon oxide film formed on the silicon nitride film 135. Thus, the element separation portion 63 having a gap G therein is allowed to be formed.

[0289] Note that Fig.33 As shown, the present embodiment illustrates an example in which the contact layer 36 electrically connecting the FD 19 (e.g., FD 19A, 19B, 19C, and 19D) provided for each unit pixel P is provided between the transfer transistors TR adjacent to each other. However, this is not restrictive. For example, Fig.39 As shown, a portion of contact layer 36 may ride on sidewall 32 of the pass transistor.

[0290] As described above, in the present embodiment, the element separation portion 63 that allows pixel transistors and the like to be separated from each other on the surface 10S1 side of the semiconductor substrate 10 has a wider shape on the surface 10S2 side of the semiconductor substrate 10 than on the surface 10S1 side. Thus, in the same manner as in the aforementioned fifth embodiment, the element formation region of the surface 10S1 of the semiconductor substrate 10 can be ensured.

[0291] As described above, in the photodetector 6 according to the present embodiment, the area efficiency of the elements formed on the surface 10S1 of the semiconductor substrate 10 can be improved, thereby reducing the pixel size. Thus, the performance as a photodetector can be improved.

[0292] Furthermore, in the photodetector 6 according to the present embodiment, the width of the element separation portion 63 on the bottom side is set, for example, to be equal to or larger than the width of the p-type diffusion region 64, thereby being able to suppress the diffusion of the p-type impurities doped in the p-type diffusion region 64 to the charge transfer path. Thus, the deterioration of the transfer characteristics caused by the dispersion of the shapes of the separation portions 51 and 52 can be reduced.

[0293] <14. Modification 8>

[0294] Fig.40 An example of a cross-sectional configuration of a photodetector (photodetector 6A) according to Modification 8 of the present invention is schematically shown. Fig.41 is the photodetector 6 corresponding to Fig.40 Schematic diagram of a planar configuration example of line AA shown. Fig.42 is the photodetector 6 corresponding to Fig.40 Schematic diagram of an example of a plane configuration of line BB shown. Fig.43 is the photodetector 6 corresponding to Fig.40 Schematic diagram of a planar configuration example of line CC shown. In the same manner as the aforementioned first embodiment, the photodetector 6A is, for example, a CMOS image sensor or the like used in electronic equipment such as a digital still camera or a video camera, and is, for example, a back-illuminated photodetector.

[0295] The aforementioned sixth embodiment explains an example in which the element separation portion 63 having a substantially trapezoidal shape and having the gap G therein is provided; however, the shape of the element separation portion 63 is not limited thereto. It is sufficient as long as the element separation portion 63 is wider on the bottom side of the separation portions 51 and 52 than on the surface 10S1 side of the semiconductor substrate 10. For example, Fig.40 As shown, the element separation portion 63 may have, for example, a substantially T-shaped cross-sectional shape including a vertical portion and a horizontal portion, and may have a shape in which a gap G is formed inside the horizontal portion.

[0296] The element separation portion 63 of this modification can be formed, for example, as follows.

[0297] In the same manner as in the aforementioned sixth embodiment, first, from the surface 10S1 side of the semiconductor substrate 10 on which the silicon nitride film 135 and the silicon oxide film 61 are stacked, a trench 12H7 is formed in the silicon nitride film 135 and the silicon oxide film 61. Fig.44A As shown, the trench 12H7 is extended into the p-well 12 by anisotropic etching.

[0298] Next, if Fig.44B As shown in FIG. 1 , isotropic etching is performed to isotropically etch the p-well 12 to form a trench 12H7. Fig.44C As shown, for example, a silicon oxide film 63A including SiO2 / LP-SiN / SiO2 is formed on the side wall of the trench 12H7. Then, in the same manner as in the aforementioned sixth embodiment, a p-type diffusion region 64 is formed, and then a silicon oxide film is embedded in the trench 12H7 using, for example, an ALD method. Thereafter, etching back is performed to remove the silicon oxide film formed on the silicon nitride film 135. Thus, an element separation portion 63 having a gap G is allowed to be formed.

[0299] As described above, the cross-sectional shape of the element separation portion 63 is not limited to a substantially trapezoidal shape. The separation portions 51 and 52 have a greater width at their bottom sides than at the surface 10S1 side of the semiconductor substrate 10, thereby achieving effects similar to those of the aforementioned sixth embodiment.

[0300] <15. Application Examples>

[0301] (Application Example 1)

[0302] In addition, the above-described photodetector (eg, photodetector 1) can be applied to, for example, various types of electronic devices including imaging systems such as digital still cameras and video cameras, mobile phones having an imaging function, or other devices having an imaging function.

[0303] Fig. 27 is a block diagram showing a configuration example of the electronic device 1000 .

[0304] like Fig. 27 As shown, the electronic device 1000 includes an optical system 1001, a light detector 1 and a DSP (digital signal processor) 1002, and in its structure, the DSP 1002, a memory 1003, a display device 1004, a recording device 1005, an operating system 1006 and a power supply system 1007 are connected together via a bus 1008, so that still images and moving images can be captured.

[0305] The optical system 1001 includes one or more lenses and acquires incident light (image light) from a subject to display the image. As shown in FIG. 23 , the electronic device 1000 includes the optical system 1001, a light detector 1 and a DSP (digital signal processor) 1002, and in its structure, the DSP 1002, a memory 1003, a display device 1004, a recording device 1005, an operating system 1006 and a power supply system 1007 are connected together via a bus 1008, thereby being able to capture still images and moving images.

[0306] The optical system 1001 includes one or more lenses and absorbs incident light (image light) from the subject to display the image. As shown in Figure 23, the electronic device 1000 includes the optical system 1001, a light detector 1 and a DSP (digital signal processor) 1002, and in its structure, the DSP 1002, a memory 1003, a display device 1004, a recording device 1005, an operating system 1006 and a power supply system 1007 are connected together via a bus 1008, so that still images and moving images can be captured.

[0307] The optical system 1001 includes one or more lenses, and absorbs incident light (image light) from a subject to form an image on an imaging surface of the photodetector 1 .

[0308] The above-described photodetector 1 is suitable as the photodetector 1. The photodetector 1 converts the amount of incident light formed as an image on the imaging surface by the optical system 1001 into electrical signals in units of pixels, and supplies the electrical signals to the DSP 1002 as pixel signals.

[0309] The DSP 1002 performs various types of signal processing on the signal from the photodetector 1 to acquire an image, and causes the memory 1003 to temporarily store data about the image. The image data stored in the memory 1003 is recorded in the recording device 1005, or is provided to the display device 1004 to display the image. In addition, the operating system 1006 receives various operations of the user and provides operation signals to the various blocks of the electronic device 1000. The power supply system 1007 provides power required to drive the various blocks of the electronic device 1000.

[0310] (Application Example 2)

[0311] Fig.28A An overall configuration example of a light detection system 2000 including the light detector 1 is schematically shown. Fig.28B2 shows a circuit configuration example of a light detection system 2000. The light detection system 2000 includes a light emitting device 2001 as a light source unit that emits infrared light L2 and a light detector 2002 as a light receiving unit having a photoelectric conversion element. The above-described light detector 1 can be used as the light detector 2002. The light detection system 2000 may further include a system control unit 2003, a light source driving unit 2004, a sensor control unit 2005, a light source side optical system 2006, and a camera side optical system 2007.

[0312] The light detector 2002 can detect light L1 and light L2. Light L1 is reflected light ( Fig.24 A). Light L2 is light reflected by the subject 2100 after being emitted by the light emitting device 2001. Light L1 is, for example, visible light, and light L2 is, for example, infrared light. Light L1 is detectable at the photoelectric conversion portion in the light detector 2002, and light L2 is detectable at the photoelectric conversion region in the light detector 2002. Image information about the subject 2100 can be acquired from light L1, and information about the distance between the subject 2100 and the light detection system 2000 can be acquired from light L2. For example, the light detection system 2000 can be installed on an electronic device such as a smartphone or on a moving body such as a car. The light emitting device 2001 can be composed of, for example, a semiconductor laser, a surface emitting semiconductor laser, or a vertical resonator surface emitting laser (VCSEL). As a method for the light detector 2002 to detect the light L2 emitted from the light emitting device 2001, an iTOF method can be adopted; however, this is not restrictive. In the iTOF method, the photoelectric conversion unit is capable of measuring the distance of the subject 2100 by, for example, the flight time of light (time of flight; TOF). As a method for the light detector 2002 to detect the light L2 emitted from the light emitting device 2001, for example, a structured light method or a stereoscopic vision method can be used. For example, in the structured light method, light having a predetermined pattern is projected onto the subject 2100, and the distortion of the pattern is analyzed, so that the distance between the light detection system 2000 and the subject 2100 can be measured. In addition, in the stereoscopic vision method, for example, two or more cameras are used to obtain two or more images of the subject 2100 viewed from two or more different viewpoints, so that the distance between the light detection system 2000 and the subject can be measured. Note that the system control unit 2003 can synchronously control the light emitting device 2001 and the light detector 2002.

[0313] <16. Practical application examples>

[0314] (Example of actual application in endoscopic surgery system)

[0315] The technology according to the embodiment of the present invention (the present technology) can be applied to various products. For example, the technology according to the embodiment of the present invention can be applied to an endoscopic surgery system.

[0316] Fig.29 : is a diagram showing a schematic configuration example of an endoscopic surgery system to which the technology according to the embodiment of the present invention (the present technology) can be applied.

[0317] exist Fig.29 , a state is shown in which a surgical operator (doctor) 11131 is using an endoscopic surgical system 11000 to perform surgery on a patient 11132 on a bed 11133. As shown in the figure, the endoscopic surgical system 11000 includes an endoscope 11100, other surgical tools 11110 such as a pneumoperitoneum tube 11111 and an energy device 11112, a support arm device 11120 for supporting the endoscope 11100 thereon, and a cart 11200 on which various endoscopic surgical devices are mounted.

[0318] The endoscope 11100 includes a lens barrel 11101 and a camera head 11102 connected to the proximal end of the lens barrel 11101, and a region of the lens barrel 11101 having a predetermined length starting from the distal end thereof is inserted into a body cavity of a patient 11132. In the illustrated example, the endoscope 11100 is shown as including a rigid endoscope including the rigid lens barrel 11101. However, the endoscope 11100 may also be a flexible endoscope including the flexible lens barrel 11101.

[0319] The lens barrel 11101 has an opening at its distal end, and the objective lens is fitted into the opening. The light source device 11203 is connected to the endoscope 11100, so that the light generated by the light source device 11203 is introduced into the distal end of the lens barrel 11101 through the light guide extending inside the lens barrel 11101, and irradiated toward the observation target in the body cavity of the patient 11132 through the objective lens. It should be noted that the endoscope 11100 can be a forward-looking endoscope, or can be an oblique-looking endoscope or a side-looking endoscope.

[0320] An optical system and an image capturing element are provided inside the camera 11102, so that the reflected light (observation light) from the observation target is focused on the image capturing element through the optical system. The observation light is photoelectrically converted by the image capturing element to generate an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image. The image signal is transmitted to the CCU 11201 as raw data.

[0321] The CCU 11201 includes a central processing unit (CPU), a graphics processing unit (GPU), etc., and integrally controls the operations of the endoscope 11100 and the display device 11202. In addition, the CCU 11201 receives an image signal from the camera 11102, and performs various image processing such as development processing (demosaic processing) on ​​the image signal to display an image based on the image signal.

[0322] Under the control of the CCU 11201 , the display device 11202 displays an image thereon based on the image signal on which the CCU 11201 has performed image processing.

[0323] The light source device 11203 includes, for example, a light source such as a light emitting diode (LED), and provides illumination light to the endoscope 11100 when imaging a surgical area.

[0324] The input device 11204 is an input interface of the endoscopic surgery system 11000. The user can input various types of information or instructions in the endoscopic surgery system 11000 through the input device 11204. For example, the user can input instructions for changing the image capturing conditions (type of irradiation light, magnification factor, focal length, etc.) of the endoscope 11100.

[0325] The treatment tool control device 11205 controls the drive of the energy device 11112 for cauterizing tissue, cutting tissue, sealing blood vessels, etc. The pneumoperitoneum device 11206 feeds gas into the body cavity of the patient 11132 through the pneumoperitoneum tube 11111 to expand the body cavity, thereby ensuring the field of view of the endoscope 11100 and ensuring the working space for the treatment operation. The recorder 11207 is a device capable of recording various information related to the operation. The printer 11208 is a device capable of recording various information related to the operation. - A device capable of printing various information related to surgery in various forms such as text, images and charts.

[0326] It should be noted that, for example, the light source device 11203 that provides irradiation light to the endoscope 11100 when imaging the surgical area may include a white light source, such as an LED, a laser light source, or a combination thereof. In the case where the white light source includes a combination of red, green, and blue (RGB) laser light sources, since the output intensity and output timing of each color (each wavelength) can be controlled with high precision, the white balance of the captured image can be adjusted by the light source device 11203. In addition, in this case, if the laser beam from the RGB laser light source is irradiated to the observation target in a time-division manner and the drive of the image capturing element of the camera 11102 is controlled in synchronization with the emission timing, images corresponding to RGB respectively can be captured in a time-division manner. According to this method, a color image can be acquired even if a color filter is not provided for the image capturing element.

[0327] In addition, the light source device 11203 can be controlled so that the intensity of the output light is changed at each predetermined time. By controlling the drive of the image capturing element of the camera 11102 in synchronization with the timing of the change in light intensity so as to acquire images in a time-division manner and synthesize the images, a high dynamic range image without underexposed shadows and overexposed highlights can be generated.

[0328] In addition, the light source device 11203 can be configured to provide light having a predetermined wavelength region domain prepared for specific light observation. In specific light observation, for example, by utilizing the wavelength dependence of light absorption in body tissue to irradiate light having a narrower band than the irradiation light (i.e., white light) during normal observation, imaging (narrow-band imaging) for predetermined tissues such as blood vessels in the surface part of the mucosal layer with high contrast is performed. Alternatively, in specific light observation, fluorescence observation for obtaining an image based on fluorescence generated by irradiation of excitation light can be performed. In fluorescence observation, observation of fluorescence from body tissue (autofluorescence observation) can be performed by irradiating body tissue, or a fluorescent image can be obtained by locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the body tissue with excitation light corresponding to the fluorescence wavelength of the reagent. The light source device 11203 can be configured to provide narrow-band light and / or excitation light suitable for specific light observation as described above.

[0329] Fig.30 It is shown Fig.29 A block diagram of an example of the functional configuration of the camera 11102 and the CCU 11201 shown.

[0330] The camera 11102 includes a lens unit 11401, an image capturing unit 11402, a driving unit 11403, a communication unit 11404, and a camera control unit 11405. The CCU 11201 includes a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera 11102 and the CCU 11201 are connected via a transmission cable 11400 to communicate with each other.

[0331] The lens unit 11401 is an optical system provided at a position connected to the lens barrel 11101. Observation light acquired from the distal end of the lens barrel 11101 is guided to the camera head 11102 and introduced into the lens unit 11401. The lens unit 11401 includes a combination of a plurality of lenses including a zoom lens and a focus lens.

[0332] The number of image capturing elements included in the image capturing unit 11402 may be one (single-board type) or multiple (multi-board type). In the case where the image capturing unit 11402 is configured as a multi-board type, for example, image signals corresponding to R, G, and B, respectively, are generated by the image capturing elements, and a color image can be obtained by synthesizing these image signals. The image capturing unit 11402 may also be configured to have a pair of image capturing elements for acquiring a right-eye image signal and a left-eye image signal for three-dimensional (3D) display. If a 3D display is performed, the surgical operator 11131 is able to more accurately perceive the depth of body tissue at the surgical site. It should be noted that in the case where the image capturing unit 11402 is configured as a multi-board type, a plurality of systems of lens units 11401 may be arranged in a manner corresponding to the respective image capturing elements.

[0333] In addition, the image capturing unit 11402 may not necessarily be disposed in the camera head 11102. For example, the image capturing unit 11402 may be disposed immediately after the objective lens inside the lens barrel 11101.

[0334] The driving unit 11403 includes an actuator, and under the control of the camera control unit 11405, the driving unit 11403 moves the zoom lens and the focus lens of the lens unit 11401 by a predetermined distance along the optical axis. Therefore, the magnification and focus of the image captured by the image capturing unit 11402 can be appropriately adjusted.

[0335] The communication unit 11404 includes a communication device for transmitting / receiving various information to / from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the image capturing unit 11402 to the CCU 11201 through the transmission cable 11400 as raw data.

[0336] In addition, the communication unit 11404 receives a control signal for controlling the driving of the camera 11102 from the CCU 11201, and provides the control signal to the camera control unit 11405. For example, the control signal includes information related to imaging conditions, such as information for specifying a frame rate for capturing an image and information for specifying an exposure value when capturing an image and / or information for specifying a magnification and a focus of a captured image.

[0337] It should be noted that image capturing conditions such as frame rate, exposure value, magnification, and focus may be appropriately specified by the user or automatically set based on the acquired image signal by the control unit 11413 of the CCU 11201. In the latter case, an automatic exposure (AE) function, an automatic focus (AF) function, and an automatic white balance (AWB) function are combined in the endoscope 11100.

[0338] The camera control unit 11405 controls the driving of the camera 11102 based on a control signal received from the CCU 11201 through the communication unit 11404 .

[0339] The communication unit 11411 includes a communication device for transmitting / receiving various types of information to / from the camera 11102. The communication unit 11411 receives an image signal transmitted from the camera 11102 through the transmission cable 11400.

[0340] In addition, the communication unit 11411 transmits a control signal for controlling the driving of the camera 11102 to the camera 11102. The image signal and the control signal may be transmitted through electrical communication, optical communication, or the like.

[0341] The image processing unit 11412 performs various image processing on the image signal transmitted from the camera 11102 in the form of raw data.

[0342] The control unit 11413 performs various types of control related to image capture of the operation area, etc. performed by the endoscope 11100 and display of captured images obtained by the image capture of the operation area, etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

[0343] In addition, the control unit 11413 controls the display device 11202 to display a captured image depicting the surgical area, etc., based on the image signal that has been image-processed by the image processing unit 11412. At this time, the control unit 11413 can identify various objects in the captured image by using various image recognition technologies. For example, the control unit 11413 can identify surgical tools such as forceps, specific living parts, bleeding, fog when using the energy device 11112, etc. by detecting the shape, color, etc. of the edge of the object included in the captured image. When the control unit 11413 controls the display device 11202 to display the captured image, the control unit 11413 can display various surgical auxiliary information in a manner superimposed with the image of the surgical area by using the recognition result. By displaying and presenting the surgical auxiliary information to the surgical operator 11131 in a superimposed manner, the burden on the surgical operator 11131 can be reduced, or the surgeon 11131 can be enabled to perform surgery more reliably.

[0344] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 to each other is an electric signal cable for electric signal communication, an optical fiber for optical communication, or a composite cable for both electric communication and optical communication.

[0345] Here, in the example shown, although communication is performed by wired communication using the transmission cable 11400, communication between the camera 11102 and the CCU 11201 may be performed by wireless communication.

[0346] An example of an endoscopic surgery system to which the technology according to an embodiment of the present invention can be applied has been described above. For example, the technology according to an embodiment of the present invention can be applied to the image capturing unit 11402 in the above-mentioned structure. By applying the technology according to an embodiment of the present invention to the image capturing unit 11402, the detection accuracy can be improved.

[0347] Note that although an endoscopic surgery system is used as an example for description here, the technology according to the embodiment of the present invention can be applied to, for example, a microscope surgery system, etc.

[0348] (Example of actual application on mobile objects)

[0349] The technology according to the embodiments of the present invention (the present technology) can be applied to various products. For example, the technology according to the embodiments of the present invention can be implemented in the form of a device installed on any type of mobile body. Non-limiting examples of mobile bodies include automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, any personal mobile devices, airplanes, unmanned aerial vehicles (UAVs), ships, robots, construction machinery, and agricultural machinery (tractors).

[0350] Fig.31 : is a block diagram showing a schematic configuration example of a vehicle control system as an example of a moving body control system to which the technology according to the embodiment of the present invention can be applied.

[0351] The vehicle control system 12000 includes a plurality of electronic control units connected to each other via a communication network 12001. Fig. 27 In the example shown, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside information detection unit 12030, an inside information detection unit 12040, and an integrated control unit 12050. In addition, a microcomputer 12051, a sound / image output section 12052, and an in-vehicle network interface (I / F) 12053 are shown as a functional configuration of the integrated control unit 12050.

[0352] The drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 acts as a control device for the following devices: a drive force generating device (such as an internal combustion engine, a drive motor, etc.) for generating a vehicle drive force, a drive force transmitting mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, a braking device for generating a vehicle braking force, etc.

[0353] The body system control unit 12020 controls the operation of various devices provided on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for the following devices: a keyless entry system, a smart key system, a power window device, or various lights such as a headlight, a reverse light, a brake light, a turn signal, a fog light, etc. In this case, a radio wave transmitted from a portable device as a key substitute or a signal of various switches may be input to the body system control unit 12020. The body system control unit 12020 receives these input radio waves or signals, and controls the door lock device, the power window device, the lights, etc. of the vehicle.

[0354] The vehicle exterior information detection unit 12030 detects external information about the vehicle including the vehicle control system 12000. For example, the vehicle exterior information detection unit 12030 is connected to the imaging unit 12031. The vehicle exterior information detection unit 12030 causes the imaging unit 12031 to capture an image of the exterior of the vehicle and receives the captured image. Based on the received image, the vehicle exterior information detection unit 12030 may perform processing for detecting objects such as people, vehicles, obstacles, signs, characters on the road surface, or processing for distance detection.

[0355] 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 may also output an electrical signal as an image, or may output an electrical signal as measured distance information. In addition, the light received by the imaging unit 12031 may be visible light, or may be invisible light such as infrared rays.

[0356] The in-vehicle information detection unit 12040 detects interior information about the vehicle. For example, the in-vehicle information detection unit 12040 is connected to a driver state detection unit 12041 for detecting a driver state. The driver state detection unit 12041 includes, for example, a camera for capturing an image of the driver. Based on the detection information input from the driver state detection unit 12041, the in-vehicle information detection unit 12040 can calculate the driver's fatigue or the driver's concentration, or can determine whether the driver is dozing off.

[0357] The microcomputer 12051 can calculate the control target value of the driving force generating device, the steering mechanism or the braking device based on the information about the inside and outside of the vehicle obtained by the vehicle outside information detection unit 12030 or the vehicle inside information detection unit 12040, and output the control command to the driving system control unit 12010. For example, the microcomputer 12051 can perform coordinated control of functions aimed at realizing an advanced driver assistance system (ADAS), including collision avoidance or shock absorption of the vehicle, following driving based on vehicle spacing, speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0358] In addition, based on the environmental information about the vehicle obtained by the external information detection unit 12030 or the internal information detection unit 12040, the microcomputer 12051 can perform coordinated control for automatic driving by controlling the driving force generating device, steering mechanism, braking device, etc., which enables the vehicle to drive automatically without relying on the driver's operation, etc.

[0359] In addition, the microcomputer 12051 can output a control command to the body system control unit 12030 based on the external information about the vehicle obtained by the vehicle exterior information detection unit 12030. For example, the microcomputer 12051 can perform coordinated control for preventing glare by, for example, controlling the headlights to change from high beam to low beam according to the position of a preceding vehicle or an oncoming vehicle detected by the vehicle exterior information detection unit 12030.

[0360] The sound / image output unit 12052 transmits an output signal of at least one of sound and image to an output device capable of visually or auditorily notifying the vehicle occupants or the outside of the vehicle of information. Fig. 27 In the example of FIG. 1 , an audio speaker 12061, a display portion 12062, and a dashboard 12063 are used as output devices. The display portion 12062 may include, for example, at least one of an in-vehicle display and a head-up display.

[0361] Fig.32 12031 is a diagram showing an example of the installation position of the imaging unit 12031.

[0362] exist Fig.32 In the embodiment, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104 and 12105.

[0363] The imaging units 12101, 12102, 12103, 12104, and 12105 are, for example, arranged at the front nose, rearview mirror, rear bumper, rear door, and upper portion of the windshield of the vehicle 12100. The imaging unit 12101 arranged at the front nose and the imaging unit 12105 arranged at the upper portion of the windshield of the vehicle mainly acquire images in front of the vehicle 12100. The imaging units 12102 and 12103 arranged at the rearview mirror mainly acquire images on both sides of the vehicle 12100. The imaging unit 12104 arranged at the rear bumper or rear door mainly acquires images behind the vehicle 12100. The imaging unit 12105 arranged at the upper portion of the windshield of the vehicle is mainly used to detect vehicles in front, pedestrians, obstacles, signal lights, traffic signs, lanes, etc.

[0364] Notice, Fig.32 An example of the imaging range of the imaging units 12101 to 12104 is shown. The imaging range 12111 indicates the imaging range of the imaging unit 12101 provided at the front nose. The imaging ranges 12112 and 12113 respectively indicate the imaging ranges of the imaging units 12102 and 12103 provided at the rearview mirror. The imaging range 12114 indicates the imaging range of the imaging unit 12104 provided at the rear bumper or the rear door. For example, a bird's-eye view image of the vehicle 12100 is obtained by superimposing the image data captured by the imaging units 12101 to 12104.

[0365] At least one of the imaging units 12101 to 12104 may have a function for obtaining distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera composed of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0366] For example, the microcomputer 12051 can determine the distance of each three-dimensional object within the imaging ranges 12111 to 12114 and the time change of the distance (relative speed with respect to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104, and extract the nearest three-dimensional object as the preceding vehicle, which is particularly present on the driving path of the vehicle 12100 and is traveling at a predetermined speed (e.g., equal to or greater than 0 km / h) in the substantially same direction as the vehicle 12100. In addition, the microcomputer 12051 is capable of presetting the following distance to be maintained in front of the preceding vehicle, and performing automatic braking control (including following stop control), automatic acceleration control (including following start control), etc. Therefore, it is possible to perform coordinated control for automatic driving so that the vehicle can travel automatically without relying on the operation of the driver, etc.

[0367] For example, the microcomputer 12051 can classify the three-dimensional object data of the three-dimensional object into two-wheeled vehicles, standard-sized vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on the distance information obtained from the imaging units 12101 to 12104, extract the classified three-dimensional object data, and use the extracted three-dimensional object data for automatic obstacle avoidance. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that can be visually identified by the driver of the vehicle 12100 and obstacles that are difficult to be visually identified by the driver of the vehicle 12100. Then, the microcomputer 12051 determines a collision risk indicating the risk of collision with each obstacle. When the collision risk is equal to or higher than the set value and therefore there is a possibility of collision, the microcomputer 12051 outputs a warning to the driver through the audio speaker 12061 or the display unit 12062, and performs forced deceleration or evasive steering through the driving system control unit 12010. The microcomputer 12051 can thereby assist driving to avoid collisions.

[0368] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 may identify a pedestrian by determining whether there is a pedestrian in the captured images of the imaging units 12101 to 12104. This pedestrian recognition is performed, for example, by the following process: a process of extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras; and a process of determining whether it is a pedestrian by performing pattern matching processing on a series of feature points representing the contour of the object. When the microcomputer 12051 determines that there is a pedestrian in the captured images of the imaging units 12101 to 12104 and thus identifies the pedestrian, the sound / image output unit 12052 controls the display unit 12062 so as to display a square contour line for emphasis superimposed on the identified pedestrian. In addition, the sound / image output unit 12052 may control the display unit 12062 so as to display an icon or the like for indicating a pedestrian at a desired position.

[0369] An example of a mobile body control system to which the technology according to an embodiment of the present invention can be applied has been described above. The technology according to an embodiment of the present invention can be applied to the imaging unit 12031 among the components of the above-mentioned structure. Specifically, the imaging element (for example, the light detector 1) according to any of the aforementioned embodiments and their modified examples can be applied to the imaging unit 12031. By applying the technology according to an embodiment of the present invention to the imaging unit 12031, a captured image with less noise and high precision can be obtained, so that the captured image can be used in the mobile body control system for high-precision control.

[0370] The present invention has been described above with reference to the first to sixth embodiments, variants 1 to 8, application examples, and practical application examples; however, the present technology is not limited to the aforementioned embodiments, etc., and can be modified in various ways. For example, the aforementioned variants 1 to 8 can be appropriately combined with other embodiments and variants.

[0371] It should be noted that the effects described herein are merely exemplary and not restrictive, and other effects may also be included.

[0372] It should be noted that the present invention can also have the following configuration. According to the present technology with the following configuration, the dispersion of the distance between the floating diffusion layer and the bottom of the second groove portion can be reduced, the pinning force on the floating diffusion layer can be reduced, and the element formation area of ​​the first surface (front side) of the semiconductor substrate can be ensured. Thus, the performance can be improved.

[0373] (1) A light detector comprising:

[0374] a semiconductor substrate having a first surface and a second surface opposite to each other, the semiconductor substrate including a plurality of pixels arranged in a matrix;

[0375] a plurality of photoelectric conversion units, each of which is formed in a manner embedded in the semiconductor substrate for each of the pixels and generates charges corresponding to the amount of received light by photoelectric conversion;

[0376] a plurality of floating diffusion layers provided on the first surface of the semiconductor substrate between the plurality of pixels adjacent to each other, the plurality of floating diffusion layers temporarily holding the charges generated in the plurality of photoelectric conversion portions provided for the respective pixels adjacent to each other;

[0377] a first groove portion, the first groove portion being provided to surround the plurality of pixels sharing the floating diffusion layer and penetrating from the first surface of the semiconductor substrate to the second surface;

[0378] a second groove portion, the second groove portion being disposed at least above the plurality of floating diffusion layers and extending from the second surface of the semiconductor substrate toward the first surface, the second groove portion having a bottom portion located in the semiconductor substrate; and

[0379] An oxide film is provided so as to be in contact with the bottom of the second groove portion.

[0380] (2) The photodetector according to (1), wherein the oxide film is provided to have a width wider than a width of the second groove portion.

[0381] (3) The photodetector according to (1) or (2), wherein the oxide film functions as an etching stopper.

[0382] (4) The photodetector according to any one of (1) to (3), wherein the oxide film includes a silicon carbide film, a silicon oxide film, or a silicon nitride film.

[0383] (5) The photodetector according to any one of (1) to (4), wherein

[0384] The semiconductor substrate has a p-well on the first surface side, and

[0385] The oxide film is disposed in the p-well.

[0386] (6) The photodetector according to any one of (1) to (5), wherein

[0387] The second groove portion extends between the plurality of pixels adjacent to each other that share the floating diffusion layer, and

[0388] The second groove portion is in contact with the first groove portion on the outer periphery of the plurality of pixels sharing the floating diffusion layer.

[0389] (7) The photodetector according to any one of (1) to (6), wherein

[0390] The first groove portion extends from the outer periphery of the plurality of pixels sharing the floating diffusion layer between the plurality of pixels adjacent to each other sharing the floating diffusion layer, and

[0391] The first trench portion is in contact with the second trench portion disposed above the plurality of floating diffusion layers.

[0392] (8) The photodetector according to any one of (1) to (7), wherein a first pinning film having positive fixed charges is formed on an inner wall of each of the first groove portion and the second groove portion.

[0393] (9) The photodetector according to (8), wherein the oxide film is formed of a second pinning film having a weaker pinning force than the first pinning film.

[0394] (10) The photodetector according to (9), wherein the second pinned film includes a hafnium oxide film.

[0395] (11) The photodetector according to (10), wherein an insulating film is further embedded in the first groove portion and the second groove portion.

[0396] (12) The photodetector according to (10), wherein a conductive film having a light shielding property is further embedded in the first groove portion and the second groove portion.

[0397] (13) The photodetector according to any one of (1) to (12), wherein a p-type diffusion region is formed along an outer wall of each of the first groove portion and the second groove portion.

[0398] (14) The photodetector according to any one of (1) to (13), wherein the floating diffusion layer is provided near intersections of four of the pixels arranged in two rows and two columns and is shared by the four pixels.

[0399] (15) A light detector comprising:

[0400] a semiconductor substrate having a first surface and a second surface opposite to each other, the semiconductor substrate including a plurality of pixels arranged in a matrix;

[0401] a plurality of photoelectric conversion units, each of which is formed in a manner embedded in the semiconductor substrate for each of the pixels and generates charges corresponding to the amount of received light by photoelectric conversion;

[0402] a plurality of floating diffusion layers provided on the first surface of the semiconductor substrate between the plurality of pixels adjacent to each other, the plurality of floating diffusion layers temporarily holding the charges generated in the plurality of photoelectric conversion portions provided for the respective pixels adjacent to each other;

[0403] a first groove portion provided to surround the plurality of pixels sharing the floating diffusion layer and to penetrate from the first surface to the second surface of the semiconductor substrate, the first groove portion having an inner wall on which a first pinning film is formed; and

[0404] A second groove portion, the second groove portion is arranged at least above the multiple floating diffusion layers and extends from the second surface of the semiconductor substrate toward the first surface, the second groove portion has a bottom located in the semiconductor substrate and has an inner wall with a second pinning film formed thereon, and the second pinning film has a weaker pinning force than the first pinning film.

[0405] (16) The photodetector according to (15), wherein:

[0406] The first groove portion extends from the outer periphery of the plurality of pixels sharing the floating diffusion layer between the plurality of pixels adjacent to each other sharing the floating diffusion layer, and

[0407] The first trench portion is in contact with the second trench portion disposed above the plurality of floating diffusion layers.

[0408] (17) A light detector comprising:

[0409] a semiconductor substrate having a first surface and a second surface opposite to each other, the semiconductor substrate including a plurality of pixels arranged in a matrix;

[0410] a plurality of photoelectric conversion units, each of which is formed in a manner embedded in the semiconductor substrate for each of the pixels and generates charges corresponding to the amount of received light by photoelectric conversion;

[0411] a first separation portion, the first separation portion being provided between the plurality of pixels adjacent to each other and extending from the second surface of the semiconductor substrate toward the first surface, the first separation portion having a bottom portion located in the semiconductor substrate; and

[0412] A second separation portion is provided between the bottom of the first separation portion and the first surface, wherein a width of the second separation portion on the bottom side of the first separation portion is greater than a width on the first surface side.

[0413] (18) The photodetector according to (17), wherein a width of the second separation portion on the bottom side of the first separation portion is larger than a width of the first separation portion.

[0414] (19) The photodetector according to (17) or (18), wherein the second separation portion has a T-shape.

[0415] (20) The photodetector according to any one of (17) to (19), wherein the second separation portion has a gap therein.

[0416] This application claims the benefit of Japanese Priority Patent Application JP2022-112817 filed in the Japan Patent Office on Jul. 14, 2022, the entire contents of which are incorporated herein by reference.

[0417] It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.

Claims

1. A light detector comprising: a semiconductor substrate having a first surface and a second surface opposite to each other, the semiconductor substrate including a plurality of pixels arranged in a matrix; a plurality of photoelectric conversion units, each of which is formed in a manner embedded in the semiconductor substrate for each of the pixels and generates charges corresponding to the amount of received light by photoelectric conversion; a plurality of floating diffusion layers provided on the first surface of the semiconductor substrate between the plurality of pixels adjacent to each other, the plurality of floating diffusion layers temporarily holding the charges generated in the plurality of photoelectric conversion portions provided for the respective pixels adjacent to each other; a first groove portion, the first groove portion being provided to surround the plurality of pixels sharing the floating diffusion layer and penetrating from the first surface of the semiconductor substrate to the second surface; a second groove portion, the second groove portion being disposed at least above the plurality of floating diffusion layers and extending from the second surface of the semiconductor substrate toward the first surface, the second groove portion having a bottom portion located in the semiconductor substrate; as well as An oxide film is provided so as to be in contact with the bottom of the second groove portion.

2. The optical detector according to claim 1, wherein The oxide film is provided to have a width wider than a width of the second groove portion.

3. The light detector according to claim 1, wherein The oxide film functions as an etching stopper.

4. The light detector according to claim 1, wherein The oxide film includes a silicon carbide film, a silicon oxide film, or a silicon nitride film.

5. The light detector according to claim 1, wherein The semiconductor substrate has a p-well on the first surface side, and The oxide film is disposed in the p-well.

6. The light detector according to claim 1, wherein The second groove portion extends between the plurality of pixels adjacent to each other that share the floating diffusion layer, and The second groove portion is in contact with the first groove portion on the outer periphery of the plurality of pixels sharing the floating diffusion layer.

7. The light detector according to claim 1, wherein The first groove portion extends from the outer periphery of the plurality of pixels sharing the floating diffusion layer between the plurality of pixels adjacent to each other sharing the floating diffusion layer, and The first trench portion is in contact with the second trench portion disposed above the plurality of floating diffusion layers.

8. The light detector according to claim 1, wherein A first pinning film having positive fixed charges is formed on an inner wall of each of the first groove portion and the second groove portion.

9. The light detector according to claim 8, wherein The oxide film is formed of a second pinning film having a weaker pinning force than the first pinning film.

10. The light detector according to claim 9, wherein The second pinning film includes a hafnium oxide film.

11. The light detector according to claim 10, wherein An insulating film is also embedded in the first groove portion and the second groove portion.

12. The light detector according to claim 10, wherein A conductive film having a light-shielding property is embedded in the first groove portion and the second groove portion.

13. The light detector according to claim 1, wherein A p-type diffusion region is formed along an outer wall of each of the first trench portion and the second trench portion.

14. The light detector according to claim 1, wherein The floating diffusion layer is provided near intersections of four of the pixels arranged in two rows and two columns, and is shared by the four pixels.

15. A light detector comprising: a semiconductor substrate having a first surface and a second surface opposite to each other, the semiconductor substrate including a plurality of pixels arranged in a matrix; a plurality of photoelectric conversion units, each of which is formed in a manner embedded in the semiconductor substrate for each of the pixels and generates charges corresponding to the amount of received light by photoelectric conversion; a plurality of floating diffusion layers provided on the first surface of the semiconductor substrate between the plurality of pixels adjacent to each other, the plurality of floating diffusion layers temporarily holding the charges generated in the plurality of photoelectric conversion portions provided for the respective pixels adjacent to each other; a first groove portion provided to surround the plurality of pixels sharing the floating diffusion layer and to penetrate from the first surface to the second surface of the semiconductor substrate, the first groove portion having an inner wall on which a first pinning film is formed; as well as A second groove portion, the second groove portion is arranged at least above the multiple floating diffusion layers and extends from the second surface of the semiconductor substrate toward the first surface, the second groove portion has a bottom located in the semiconductor substrate and has an inner wall with a second pinning film formed thereon, and the second pinning film has a weaker pinning force than the first pinning film.

16. The light detector according to claim 15, wherein The first groove portion extends from the outer periphery of the plurality of pixels sharing the floating diffusion layer between the plurality of pixels adjacent to each other sharing the floating diffusion layer, and The first trench portion is in contact with the second trench portion disposed above the plurality of floating diffusion layers.

17. A light detector comprising: a semiconductor substrate having a first surface and a second surface opposite to each other, the semiconductor substrate including a plurality of pixels arranged in a matrix; a plurality of photoelectric conversion units, each of which is formed in a manner embedded in the semiconductor substrate for each of the pixels and generates charges corresponding to the amount of received light by photoelectric conversion; a first separation portion, the first separation portion being disposed between the plurality of pixels adjacent to each other and extending from the second surface of the semiconductor substrate toward the first surface, the first separation portion having a bottom portion located in the semiconductor substrate; as well as A second separation portion is provided between the bottom of the first separation portion and the first surface, wherein a width of the second separation portion on the bottom side of the first separation portion is greater than a width on the first surface side.

18. The light detector according to claim 17, wherein The width of the second separation portion on the bottom side of the first separation portion is greater than the width of the first separation portion.

19. The light detector according to claim 17, wherein The second separation portion has a T-shape.

20. The light detector according to claim 17, wherein The second separation portion has a gap therein.

Images