Light detection device

Abstract

To provide a light detection device that makes it possible to improve performance.SOLUTION: In a light detection device, a first pixel has a first photoelectric conversion part, a first charge holding part capable of holding charges transferred from the first photoelectric conversion part, and a first light shield part provided between a first face and the first charge holding part. A second pixel has a second photoelectric conversion part, a second charge holding part capable of holding charges transferred from the second photoelectric conversion part, and a second light shield part provided between the first face and the second charge holding part. In a plan view, a first opening provided in the first light shield part and a second opening provided in the second light shield part are line symmetrical. In a plan view, a first end part along the first opening part of the first light shield part and a second end part along the second opening part of the second light shield part respectively extend in a direction diagonally crossing both of first and second directions.SELECTED DRAWING: Figure 4E

Description

[Technical field]

[0001] The present disclosure relates to a light detection device. [Background technology]

[0002] 2. Description of the Related Art There is known an imaging device having a structure in which a photodiode and a memory are stacked in the light incidence direction, and a light-shielding film is disposed between the photodiode and the memory (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 117648 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for further improvement in the performance of this type of imaging device.

[0005] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a light detection device that enables improved performance. [Means for solving the problem]

[0006] A photodetector according to an embodiment of the present disclosure includes a semiconductor substrate having a first surface and a second surface located opposite to the first surface, and a plurality of sensor pixels provided on the semiconductor substrate. Each of the plurality of sensor pixels includes a first pixel and a second pixel adjacent to the first pixel in a first direction parallel to the first surface. The first pixel includes a first photoelectric conversion unit capable of generating a charge by photoelectrically converting light incident from the first surface side, a first charge holding unit provided on the opposite side of the first surface across the first photoelectric conversion unit and capable of holding the charge transferred from the first photoelectric conversion unit, and a first light shielding unit provided between the first surface and the first charge holding unit. The second pixel has a second photoelectric conversion unit capable of generating a charge by photoelectrically converting light incident from the first surface side, a second charge holding unit provided on the opposite side of the first surface across the second photoelectric conversion unit and capable of holding the charge transferred from the second photoelectric conversion unit, and a second light-shielding unit provided between the first surface and the second charge holding unit. In a plan view from a normal direction of the first surface, a first opening provided in the first light-shielding unit and a second opening provided in the second light-shielding unit are line-symmetric with respect to a straight line passing through a center of the sensor pixel and parallel to a second direction perpendicular to the first direction. In the plan view, a first end portion of the first light-shielding unit along the first opening and a second end portion of the second light-shielding unit along the second opening extend in a direction obliquely intersecting both the first direction and the second direction.

[0007] According to this, the first light-shielding portion and the second light-shielding portion can suppress the incidence of light into the first charge-holding portion and the second charge-holding portion, so that it is possible to reduce PLS (Parasitic Light Sensitivity). In addition, the first opening provided in the first light-shielding portion and the second opening provided in the second light-shielding portion are line-symmetrical with respect to a straight line passing through the center of the sensor pixel. This makes it possible to reduce the difference in sensitivity to incident light between the first pixel and the second pixel. Furthermore, the first light-shielding portion has an oblique first end portion, and the second light-shielding portion has an oblique second end portion. This makes it possible to achieve both improved charge transfer efficiency and PLS suppression. From the above, it is possible to improve the performance of the photodetector. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram illustrating an example of a functional configuration of an imaging device according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing an example of a circuit configuration of two adjacent pixels of a sensor pixel according to the first embodiment of the present disclosure. [Diagram 3] FIG. 3 is a cross-sectional view illustrating a configuration example of a sensor pixel according to the first embodiment of the present disclosure. [Figure 4A] FIG. 4A is a plan view illustrating a configuration example of a sensor pixel according to the first embodiment of the present disclosure. [Figure 4B] FIG. 4B is a plan view illustrating a configuration example of a sensor pixel according to the first embodiment of the present disclosure. [Figure 4C] FIG. 4C is a plan view illustrating a configuration example of a sensor pixel according to the first embodiment of the present disclosure. [Figure 4D] FIG. 4D is a plan view illustrating a configuration example of a sensor pixel according to the first embodiment of the present disclosure. [Figure 4E] FIG. 4E is a plan view illustrating a configuration example of a sensor pixel according to the first embodiment of the present disclosure. [Figure 5A] FIG. 5A is a plan view showing a horizontal light-shielding portion according to a comparative example of the present disclosure and an opening provided in the horizontal light-shielding portion. [Figure 5B] FIG. 5B is a plan view illustrating a horizontal light-shielding portion and an opening provided in the horizontal light-shielding portion according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is a cross-sectional view illustrating a configuration example of a sensor pixel according to the second embodiment of the present disclosure. [Figure 7A] FIG. 7A is a plan view illustrating a configuration example of a sensor pixel according to the second embodiment of the present disclosure. [Figure 7B] FIG. 7B is a plan view illustrating a configuration example of a sensor pixel according to the second embodiment of the present disclosure. [Figure 7C] FIG. 7C is a plan view illustrating a configuration example of a sensor pixel according to the second embodiment of the present disclosure. [Figure 7D]FIG. 7D is a plan view illustrating a configuration example of a sensor pixel according to the second embodiment of the present disclosure. [Figure 8] FIG. 8 is a cross-sectional view showing a configuration of a sensor pixel according to Modification 1 of Embodiment 2 of the present disclosure. [Figure 9] FIG. 9 is a plan view showing a configuration of a sensor pixel according to Modification 1 of Embodiment 2 of the present disclosure. [Figure 10] FIG. 10 is a cross-sectional view showing a configuration of a sensor pixel according to Modification 2 of Embodiment 2 of the present disclosure. [Figure 11] FIG. 11 is a plan view showing a configuration of a sensor pixel according to Modification 2 of Embodiment 2 of the present disclosure. [Figure 12] FIG. 12 is a cross-sectional view showing a configuration of a sensor pixel according to Modification 3 of Embodiment 2 of the present disclosure. [Figure 13] FIG. 13 is a plan view illustrating a configuration of a sensor pixel according to Modification 3 of Embodiment 2 of the present disclosure. [Figure 14] FIG. 14 is a cross-sectional view showing a configuration of a sensor pixel according to the fourth modification of the second embodiment of the present disclosure. [Figure 15A] FIG. 15A is a cross-sectional view showing a configuration of a sensor pixel according to Modification 5 of Embodiment 2 of the present disclosure. [Figure 15B] FIG. 15B is a cross-sectional view showing the configuration of a sensor pixel according to Modification 5 of Embodiment 2 of the present disclosure. [Figure 16A] FIG. 16A is a plan view showing a configuration of a sensor pixel according to Modification 5 of Embodiment 2 of the present disclosure. [Figure 16B] FIG. 16B is a plan view showing the configuration of a sensor pixel according to Modification 5 of Embodiment 2 of the present disclosure. [Figure 16C] FIG. 16C is a plan view showing a configuration of a sensor pixel according to Modification 5 of Embodiment 2 of the present disclosure. [Figure 16D] FIG. 16D is a plan view showing a configuration of a sensor pixel according to Modification 5 of Embodiment 2 of the present disclosure. [Figure 16E] FIG. 16E is a plan view showing a configuration of a sensor pixel according to Modification 5 of Embodiment 2 of the present disclosure. [Figure 17]FIG. 17 is a cross-sectional view showing a configuration of a sensor pixel according to the sixth modification of the second embodiment of the present disclosure. [Figure 18A] FIG. 18A is a plan view showing a configuration of a sensor pixel according to Modification 6 of Embodiment 2 of the present disclosure. [Figure 18B] FIG. 18B is a plan view showing the configuration of a sensor pixel according to Modification 6 of Embodiment 2 of the present disclosure. [Figure 19] 19A to 19C are cross-sectional views illustrating a process sequence of a trench formation method suitable for the sixth modification of the second embodiment of the present disclosure. [Figure 20] FIG. 20 is a diagram showing an example of the configuration of an electronic device to which the present technology can be applied. [Figure 21] FIG. 21 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a moving object control system to which the technology according to the present disclosure can be applied. [Figure 22] FIG. 22 is a diagram showing an example of the installation position of the imaging unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the description of the drawings referred to in the following description, the same or similar parts are denoted with the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc., differ from the actual ones. Therefore, the specific thickness and dimensions should be determined with reference to the following description. In addition, it goes without saying that the drawings include parts with different dimensional relationships and ratios.

[0010] The definitions of directions such as up and down in the following description are merely for the convenience of explanation and do not limit the technical ideas of the present disclosure. For example, if an object is rotated 90 degrees and observed, up and down are converted to left and right and read, and if it is rotated 180 degrees and observed, up and down are obviously read inverted.

[0011] In the following description, the thickness direction of the semiconductor substrate 10 means the direction from one of the front surface 10a and the back surface 10b of the semiconductor substrate to the other. The thickness direction of the semiconductor substrate 10 is the normal direction of the front surface 10a of the semiconductor substrate 10 and is also the normal direction of the back surface 10b of the semiconductor substrate 10.

[0012] In the following description, a plan view means a view from the thickness direction of the semiconductor substrate 10 (that is, a normal direction to the front surface 10a or back surface 10b of the semiconductor substrate 10).

[0013] <Embodiment 1> (Example of overall configuration of imaging device) 1 is a block diagram showing an example of a functional configuration of an imaging device 101 according to a first embodiment of the present disclosure. The imaging device 101 is an example of a "photodetection device" of the present disclosure, and is, for example, a so-called global shutter type back-illuminated image sensor such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The imaging device 101 captures an image by receiving light from a subject, photoelectrically converting the light, and generating an image signal.

[0014] The global shutter method is a method of performing global exposure in which exposure of all pixels is basically started and ended at the same time. Here, all pixels means all pixels that appear in an image, excluding dummy pixels and the like. In addition, if the time difference and image distortion are small enough to be negligible, the global shutter method also includes a method of performing global exposure in units of multiple rows (e.g., several tens of rows) rather than all pixels at the same time, while moving the area where global exposure is performed. In addition, the global shutter method also includes a method of performing global exposure on pixels in a specified area, rather than on all pixels that appear in an image.

[0015] A back-illuminated image sensor is an image sensor in which a photoelectric conversion unit such as a photodiode that receives light from a subject and converts it into an electrical signal is provided between a light-receiving surface where the light from the subject is incident and a wiring layer on which wiring such as transistors that drive each pixel is provided.

[0016] The imaging device 101 includes, for example, a pixel array unit 111, a vertical drive unit 112, a column signal processing unit 113, a data storage unit 119, a horizontal drive unit 114, a system control unit 115, and a signal processing unit 118.

[0017] In the imaging device 101, a pixel array section 111 is formed on a semiconductor substrate 10 (described later). Peripheral circuits such as a vertical drive section 112, a column signal processing section 113, a data storage section 119, a horizontal drive section 114, a system control section 115, and a signal processing section 118 are formed on the same semiconductor substrate 10 as the pixel array section 111, for example.

[0018] The pixel array section 111 has a plurality of sensor pixels PX, each including a photoelectric conversion section PD (described later) that generates and accumulates electric charges according to the amount of light incident from a subject. As shown in Fig. 1, the sensor pixels PX are arranged in a horizontal direction (row direction) and a vertical direction (column direction). In the pixel array section 111, a pixel drive line 116 is wired along the row direction for each pixel row made up of sensor pixels PX arranged in a row direction, and a vertical signal line VSL is wired along the column direction for each pixel column made up of sensor pixels PX arranged in a column direction.

[0019] The vertical driving unit 112 includes a shift register, an address decoder, etc. The vertical driving unit 112 supplies signals and the like to the plurality of sensor pixels PX via the plurality of pixel driving lines 116, thereby driving all of the plurality of sensor pixels PX in the pixel array unit 111 simultaneously or driving them on a pixel row basis.

[0020] Signals output from each unit pixel of a pixel row selected and scanned by the vertical drive section 112 are supplied through each vertical signal line VSL to a column signal processing section 113. The column signal processing section 113 performs predetermined signal processing on signals output from each unit pixel of a selected row through the vertical signal line VSL for each pixel column of the pixel array section 111, and temporarily holds the pixel signals after signal processing.

[0021] Specifically, the column signal processing unit 113 is composed of, for example, a shift register and an address decoder, and performs noise removal processing, correlated double sampling processing, A / D (Analog / Digital) conversion processing of analog pixel signals, etc. to generate digital pixel signals. The column signal processing unit 113 supplies the generated pixel signals to the signal processing unit 118.

[0022] The horizontal driving unit 114 is composed of a shift register, an address decoder, etc., and is configured to sequentially select unit circuits corresponding to pixel columns of the column signal processing unit 113. By selective scanning by this horizontal driving unit 114, pixel signals that have been signal-processed for each unit circuit in the column signal processing unit 113 are output to the signal processing unit 118 in sequence.

[0023] The system control unit 115 is composed of a timing generator that generates various timing signals, etc. The system control unit 115 controls the driving of the vertical driving unit 112, the column signal processing unit 113, and the horizontal driving unit 114 based on the timing signals generated by the timing generator.

[0024] The signal processing unit 118 performs signal processing such as arithmetic processing on the pixel signals supplied from the column signal processing unit 113 while temporarily storing the data in a data storage unit 119 as necessary, and outputs a pixel signal made up of each pixel signal.

[0025] The data storage unit 119 temporarily stores data necessary for the signal processing performed by the signal processing unit 118 .

[0026] (Example of circuit configuration of sensor pixel PX) Next, a circuit configuration example of the sensor pixel PX provided in the pixel array unit 111 of Fig. 1 will be described with reference to Fig. 2. Fig. 2 illustrates a circuit configuration example of two adjacent pixels PX(R) and PX(L) of the sensor pixel PX according to the first embodiment of the present disclosure.

[0027] In the example shown in FIG. 2, the sensor pixel PX in the pixel array unit 111 realizes a memory-retention type global shutter system. A pixel PX(R), which is a part of the sensor pixel PX, is an example of a "first pixel" in the present disclosure, and has a photoelectric conversion unit PD(R) (an example of a "first photoelectric conversion unit" in the present disclosure), a first transfer transistor TG(R)A, a second transfer transistor TG(R)B, a third transfer transistor TG(R)C, a charge retention unit MEM(R) (an example of a "first charge retention unit" in the present disclosure), and a discharge transistor OFG(R). The first transfer transistor TG(R)A includes a transfer gate TRZ(R). The second transfer transistor TG(R)B includes a transfer gate TRX(R). The third transfer transistor TG(R)C includes a transfer gate TRG(R).

[0028] Similarly, pixel PX(L), which is another part of sensor pixel PX, is an example of a "second pixel" in the present disclosure, and includes a photoelectric conversion unit PD(L) (an example of a "second photoelectric conversion unit" in the present disclosure), a first transfer transistor TG(L)A, a second transfer transistor TG(L)B, a third transfer transistor TG(L)C, a charge holding unit MEM(L) (an example of a "second charge holding unit" in the present disclosure), and a discharge transistor OFG(L). The first transfer transistor TG(L)A includes a transfer gate TRZ(L). The second transfer transistor TG(L)B includes a transfer gate TRX(L). The third transfer transistor TG(L)C includes a transfer gate TRG(L).

[0029] Furthermore, the pixel PX(R) and the pixel PX(L) share a power supply VDD, a charge-voltage conversion unit FD, a reset transistor RST, an amplification transistor AMP, and a selection transistor SEL, etc. In this example, the first transfer transistors TG(R)A, TG(L)A, the second transfer transistors TG(R)B, TG(L)B, the third transfer transistors TG(R)C, TG(L)C, the reset transistor RST, the amplification transistor AMP, and the selection transistor SEL are all N-type MOS transistors.

[0030] A drive signal is supplied to each gate electrode of the first transfer transistors TG(R)A, TG(L)A, the second transfer transistors TG(R)B, TG(L)B, the third transfer transistors TG(R)C, TG(L)C, the reset transistor RST, the amplifying transistor AMP, and the selection transistor SEL by the vertical drive unit 112 and the horizontal drive unit 114 under the drive control of the system control unit 115. These drive signals are pulse signals whose high level state is an active state (on state) and whose low level state is an inactive state (off state). Note that, hereinafter, turning a drive signal into an active state is also referred to as turning the drive signal on, and turning a drive signal into an inactive state is also referred to as turning the drive signal off.

[0031] The photoelectric conversion units PD(R), PD(L) are photoelectric conversion elements formed, for example, of PN junction photodiodes, and are configured to receive light from the subject, generate electric charges according to the amount of light received through photoelectric conversion, and accumulate the electric charges.

[0032] The charge holding units MEM(R), MEM(L) are provided between the photoelectric conversion units PD(R), PD(L) and the charge-voltage conversion unit FD, respectively. The charge holding units MEM(R), MEM(L) are regions that temporarily hold the charges generated and accumulated in the photoelectric conversion units PD(R), PD(L) until the charges are transferred to the charge-voltage conversion unit FD in order to realize a global shutter function.

[0033] The first transfer transistor TG(R)A is disposed between the photoelectric conversion unit PD(R) and the second transfer transistor TG(R)B. The second transfer transistor TG(R)B is disposed between the first transfer transistor TG(R)A and the charge holding unit MEM(R). The third transfer transistor TG(R)C is disposed between the charge holding unit MEM(R) and the charge-voltage conversion unit FD. The first transfer transistor TG(R)A and the second transfer transistor TG(R)B are configured to transfer the charge stored in the photoelectric conversion unit PD(R) to the charge holding unit MEM(R) in response to a drive signal applied to their gate electrodes.

[0034] For example, when the discharge transistor OFG(R) is turned off and the first transfer transistor TG(R)A and the second transfer transistor TG(R)B are turned on, the charge stored in the photoelectric conversion unit PD(R) is transferred from the photoelectric conversion unit PD(R) to the charge holding unit MEM(R).

[0035] Similarly, the first transfer transistor TG(L)A is disposed between the photoelectric conversion unit PD(L) and the second transfer transistor TG(L)B. The second transfer transistor TG(L)B is disposed between the first transfer transistor TG(L)A and the charge holding unit MEM(L). The third transfer transistor TG(L)C is disposed between the charge holding unit MEM(L) and the charge-voltage conversion unit FD. The first transfer transistor TG(L)A and the second transfer transistor TG(L)B are configured to transfer the charge stored in the photoelectric conversion unit PD(L) to the charge holding unit MEM(L) in response to a drive signal applied to their gate electrodes.

[0036] For example, when the discharge transistor OFG(L) is turned off and the first transfer transistor TG(L)A and the second transfer transistor TG(L)B are turned on, the charge stored in the photoelectric conversion unit PD(L) is transferred from the photoelectric conversion unit PD(L) to the charge holding unit MEM(L).

[0037] The third transfer transistors TG(R)C, TG(L)C are configured to transfer the charges temporarily stored in the charge holding units MEM(R) and MEM(L) to the charge-voltage conversion unit FD in response to drive signals applied to their gate electrodes.

[0038] In pixels PX(R) and PX(L), for example, when the third transfer transistors TG(R)C and TG(L)C are turned on, the charges held in the charge holding units MEM(R) and MEM(L), respectively, are transferred to the charge-voltage conversion unit FD via the third transfer transistors TG(R)C and TG(L)C.

[0039] The reset transistor RST has a drain connected to a power supply VDD and a source connected to the charge-voltage conversion unit FD. The reset transistor RST initializes, i.e. resets, the charge-voltage conversion unit FD in response to a drive signal applied to its gate electrode. For example, when the reset transistor RST is turned on by a drive signal, the potential of the charge-voltage conversion unit FD is reset to the voltage level of the power supply VDD. In other words, the charge-voltage conversion unit FD is initialized.

[0040] The charge-voltage conversion unit FD is a floating diffusion region that converts the charges transferred from the photoelectric conversion units PD(R) and PD(L) via the first transfer transistors TG(R)A and TG(L)A, the second transfer transistors TG(R)B and TG(L)B, the charge holding units MEM(R) and MEM(L), and the third transfer transistors TG(R)C and TG(L)C into electrical signals (e.g., voltage signals) and outputs the electrical signals. The charge-voltage conversion unit FD is connected to a reset transistor RST and is also connected to a vertical signal line VSL via an amplification transistor AMP and a selection transistor SEL.

[0041] The amplification transistor AMP outputs an electrical signal according to the potential of the charge-voltage conversion unit FD. The amplification transistor AMP constitutes a source follower circuit together with a constant current source provided in the column signal processing unit 113, for example. The selection transistor SEL is turned on when the sensor pixel PX is selected, and outputs the electrical signal from the charge-voltage conversion unit FD via the amplification transistor AMP to the column signal processing unit 113 via the vertical signal line VSL.

[0042] The sensor pixels PX(R), PX(L) each further include a power supply VDD in addition to the charge-voltage converter FD as a transfer destination of the charges of the photoelectric converters PD(R), PD(L). The discharge transistor OFG(R) is disposed between the drain of the transfer transistor TG(R)A and the power supply VDD. The discharge transistor OFG(L) is disposed between the drain of the transfer transistor TG(L)A and the power supply VDD.

[0043] The discharge transistor OFG(R) has a drain connected to a power supply VDD and a source connected to the drain of the transfer transistor TG(R)A. Similarly, the discharge transistor OFG(L) has a drain connected to a power supply VDD and a source connected to the drain of the transfer transistor TG(L)A. The discharge transistors OFG(R), OFG(L) initialize, i.e., reset, the photoelectric conversion units PD(R), PD(L) in response to a drive signal applied to each gate electrode. Resetting the photoelectric conversion units PD(R), PD(L) means depleting the photoelectric conversion units PD(R), PD(L).

[0044] For example, the first transfer transistors TG(R)A, TG(L)A are turned on, and the discharge transistors OFG(R), OFG(L) are turned on, whereby the photoelectric conversion units PD(R), PD(L) are reset.

[0045] Furthermore, the discharge transistors OFG(R), OFG(L) each form an overflow path, and discharge the charge overflowing from the photoelectric conversion units PD(R), PD(L) to the power supply VDD. However, when resetting the photoelectric conversion units PD(R), PD(L), it is necessary to turn on the discharge transistors OFG(R), OFG(L) and the transfer gates TRZ(R), TRZ(L) at the same time.

[0046] (Example of cross-sectional and planar configuration of sensor pixel PX) Next, a cross-sectional and planar configuration example of the sensor pixel PX will be described with reference to FIG. 3 and FIGS. 4A to 4E. FIG. 3 is a cross-sectional view showing a configuration example of the sensor pixel PX according to the first embodiment of the present disclosure. FIGS. 4A to 4E are plan views showing a configuration example of the sensor pixel PX according to the first embodiment of the present disclosure. To explain in detail, FIG. 3 shows a cross-sectional configuration example obtained by cutting each of the plan views of FIGS. 4A to 4D along the lines A1-A1′ and A4-A4′. FIGS. 4A to 4D show planar configuration examples at each position of LV1 to LV4 in the cross-sectional view of FIG. 3. FIG. 4E shows an enlarged planar configuration example when one sensor pixel PX is viewed from the rear surface 10b side, and more specifically, shows an enlarged overlapping view of the plan views of LV1 and LV2 shown in FIGS. 4A and 4B.

[0047] The semiconductor substrate 10 is, for example, a silicon (Si) substrate, and its front surface 10a and back surface 10b are (111) surfaces. In a pixel array section 111 provided on the semiconductor substrate 10, sensor pixels PX shown in Fig. 4A to Fig. 4E are repeatedly arranged along each of the X-axis direction and the Y-axis direction. Each of the sensor pixels PX has the same shape as the other sensor pixels PX in a plan view, or a shape that is horizontally inverted or vertically inverted, and has substantially the same structure.

[0048] As shown in Figures 4A to 4D, the multiple sensor pixels PX are arranged side by side in a first direction (e.g., left-right direction on the paper) parallel to the rear surface 10b (one example of a "first surface" in the present disclosure) of the semiconductor substrate 10, and in a second direction (e.g., up-down direction on the paper) perpendicular to the first direction. An inter-pixel separator 30 is provided between one sensor pixel PX and the other sensor pixel PX adjacent to each other in the first direction or the second direction. The inter-pixel separator 30 separates the one sensor pixel PX from the other sensor pixel PX. The configuration of the inter-pixel separator 30 will be described later.

[0049] 3 and 4A to 4E, each of the sensor pixels PX includes a pixel PX(R) (an example of a "first pixel" in the present disclosure) and a pixel PX(L) (an example of a "second pixel" in the present disclosure). The pixels PX(R) and PX(L) are adjacent to each other in a first direction (for example, the left-right direction on the paper of each of FIGS. 3 to 4E).

[0050] 3, an on-chip lens OCL is provided on the back surface 10b side of the semiconductor substrate 10 via an insulating film 11 such as a silicon oxide film (SiO film) and a color filter CF. For example, one on-chip lens OCL is provided on pixels PX(R) and PX(L) included in one pixel PX via color filters CF of the same color.

[0051] As shown in FIG. 3 to FIG. 4E, the pixel PX(R) has a photoelectric conversion unit PD(R) (the "first photoelectric conversion unit" of the present disclosure), a charge holding unit MEM(R) (the "first photoelectric conversion unit" of the present disclosure), and a horizontal light shielding unit LS1(R) (an example of the "first light shielding unit" of the present disclosure). The photoelectric conversion unit PD(R) has a function of generating charges by photoelectrically converting light (hereinafter also referred to as incident light) that has passed through the on-chip lens OCL, the color filter CF, and the insulating film 11 and is incident from the back surface 10b side of the semiconductor substrate 10. The charge holding unit MEM(R) is provided on the opposite side of the back surface 10b (i.e., the front surface side) with the photoelectric conversion unit PD(R) in between, and has a function of holding charges transferred from the photoelectric conversion unit PD(R). The horizontal light shielding unit LS1(R) is provided between the back surface of the semiconductor substrate and the MEM(R).

[0052] Similarly, pixel PX(L) has a photoelectric conversion unit PD(L) (the "second photoelectric conversion unit" of the present disclosure), a charge holding unit MEM(L) (the "second photoelectric conversion unit" of the present disclosure), and a horizontal light shielding unit LS1(L) (an example of the "second light shielding unit" of the present disclosure). The photoelectric conversion unit PD(L) has a function of performing photoelectric conversion of incident light to generate electric charge. The charge holding unit MEM(L) is provided on the front surface 10a side of the semiconductor substrate 10, and has a function of holding electric charge transferred from the photoelectric conversion unit PD(L). The horizontal light shielding unit LS1(L) is provided between the rear surface of the semiconductor substrate and the charge holding unit MEM(L).

[0053] As shown in FIG. 3, the horizontal light shielding portions LS1(R) and LS1(L) are provided parallel to the back surface 10b of the semiconductor substrate 10, which is the light incident surface, and at the same depth from the back surface 10b.

[0054] 3 to 4E, the inter-pixel isolation section 30 has a first inter-pixel isolation section 31 and a second inter-pixel isolation section 32. One sensor pixel PX and the other sensor pixel PX are electrically isolated by the first inter-pixel isolation section 31 and the second inter-pixel isolation section 32. In addition, a space S30 (an example of a "second space" in the present disclosure) is provided between the first inter-pixel isolation section 31 and the second inter-pixel isolation section 32, the space S30 communicating between one sensor pixel PX and the other sensor pixel PX adjacent to each other in a first direction (e.g., the left-right direction on the paper) or a second direction (e.g., the up-down direction on the paper).

[0055] The space S30 is formed of, for example, a p-type region 12, and forms a pn junction with the photoelectric conversion unit PD(R) or PD(L) formed of an n-type region. This pn junction forms a depletion layer in the space S30. As a result, even in the region where the space S30 exists, one sensor pixel PX and the other sensor pixel PX are electrically isolated from each other.

[0056] Each of the multiple sensor pixels PX is provided with an intra-pixel separator 20 that separates one pixel PX(R) and the other pixel PX(L) that are adjacent to each other in a first direction (e.g., the left-right direction on the paper). The pixels PX(R) and PX(L) are arranged symmetrically with respect to a line CL that passes through the center of the pixel and is parallel to a second direction (e.g., the up-down direction on the paper). The intra-pixel separator 20 is arranged so as to overlap with this line CL (i.e., the axis of symmetry).

[0057] The pixel isolation section 20 has a first pixel isolation section 21 and a second pixel isolation section 22. Between the first pixel isolation section 21 and the second pixel isolation section 22, a space S20 (an example of the "first space" in the present disclosure) is provided that connects one pixel PX(R) and the other pixel PX(L) adjacent to each other in a first direction (for example, the left-right direction on the paper). This space S20 is, for example, formed of a p-type region 12, and forms a pn junction with the photoelectric conversion units PD(R) and PD(L) formed of an n-type region. This pn junction forms a depletion layer in the space S20. As a result, even in the region where the space S20 exists, the adjacent pixels PX(R) and PX(L) are electrically isolated from each other.

[0058] 3, the semiconductor substrate 10 may be provided with an n-type region 13 having a higher n-type impurity concentration than the photoelectric conversion units PD(R) and PD(L) and in contact with the p-type region 12. For example, the n-type region 13 may be provided in a region facing the intra-pixel isolation unit 20 across the p-type region 12 and a region facing the inter-pixel isolation unit 30 across the p-type region 12. Of these regions, the n-type region 13 may be provided only on the side closer to the surface 10a of the semiconductor substrate 10 than the horizontal light shielding units LS1(R) and LS1(L). The presence of the n-type region 13 can increase the number of electrons stored in the photoelectric conversion unit PD, thereby expanding the dynamic range.

[0059] Each of the charge retention units MEM(R), MEM(L) is composed of an n-type region 14 provided on the surface 10a side of the semiconductor substrate 10 and a p-type region 15 surrounding the n-type region 14. The n-type impurity concentration of the n-type region 14 may be the same as that of the n-type regions constituting the pixels PX(R), PX(L), or may not be the same. The p-type impurity concentration of the p-type region 15 may be the same as that of the p-type region 12, or may not be the same. The p-type region 15 may be formed integrally with the p-type region 12, or may not be the same.

[0060] 3, the transfer gates TRZ(R), TRZ(L) are provided with a vertical gate VG that penetrates the p-type region 15 in the thickness direction of the semiconductor substrate 10. When the transfer gates TRZ(R), TRZ(L) are turned on, a channel is formed along the vertical gate VG, and charges are transferred from the pixels PX(R), PX(L) to the charge holding units MEM(R), MEM(L), respectively.

[0061] In the sensor pixel PX shown in FIG. 3 to FIG. 4E, the first intra-pixel isolation portion 21, the first inter-pixel isolation portion 31, the horizontal light-shielding portion LS1(R), and the horizontal light-shielding portion LS1(L) are integrally formed. For example, the first intra-pixel isolation portion 21 (one example of a "part of the intra-pixel isolation portion" in the present disclosure) and the first inter-pixel isolation portion 31 (one example of a "other part of the inter-pixel isolation portion" in the present disclosure) each have a first trench 51 provided in the thickness direction of the semiconductor substrate 10, and a first metal film 61 provided in the first trench 51 via an insulating film 55. The first trench 51 may or may not penetrate the semiconductor substrate 10 in the thickness direction. FIG. 3 illustrates a case where the first trench 51 penetrates the semiconductor substrate 10 in the thickness direction.

[0062] Each of the horizontal light-shielding portion LS1(R) and the horizontal light-shielding portion LS1(L) has a space portion 52 provided in a horizontal direction perpendicular to the thickness direction of the semiconductor substrate 10, and a first metal film 61 provided in the space portion 52 via an insulating film 55. The first trench 51 of the first intra-pixel isolation portion 21 and the first trench 51 of the inter-pixel isolation portion 31 communicate (connect) with each other via the space portion 52. The insulating film 55 in the first trench 51 and the insulating film 55 in the space portion 52 are integrally formed, and the first metal film 61 in the first trench 51 and the first metal film 61 in the space portion 52 are also integrally formed.

[0063] Further, the second intra-pixel isolation portion 22 and the second inter-pixel isolation portion 32 are integrally formed. For example, the second intra-pixel isolation portion 22 and the second inter-pixel isolation portion 32 each have a second trench 53 penetrating the semiconductor substrate 10 in the thickness direction, and a second metal film 62 provided in the second trench 53 with an insulating film 56 interposed therebetween.

[0064] The first metal film 61 and the second metal film 62 are made of a material containing at least one of a light-shielding elemental metal, a metal alloy, a metal nitride, and a metal silicide. Specifically, the first metal film 61 and the second metal film 62 are made of a material containing at least one of Al (aluminum), Cu (copper), Co (cobalt), W (tungsten), Ti (titanium), Ta (tantalum), Ni (nickel), Mo (molybdenum), Cr (chromium), Ir (iridium), platinum iridium, TiN (titanium nitride), or a tungsten silicon compound. The first metal film 61 and the second metal film 62 may or may not be made of the same material.

[0065] The horizontal light shielding portion LS1(R) is provided with an opening H1 (an example of a "first opening" in the present disclosure) penetrating the horizontal light shielding portion LS1(R). The horizontal light shielding portion LS1(L) is provided with an opening H2 (an example of a "second opening" in the present disclosure) penetrating the horizontal light shielding portion LS1(L). As shown in FIG. 4E, in a plan view, the opening H1 provided in the horizontal light shielding portion LS1(R) and the opening H2 provided in the horizontal light shielding portion LS1(L) are line-symmetrical with respect to a straight line CL that passes through the center of the sensor pixel PX and is parallel to a second direction (e.g., the vertical direction in the paper) perpendicular to the first direction (e.g., the horizontal direction in the paper). In a planar view, end EDG1 (an example of a "first end" in this disclosure) along the opening H1 of horizontal shading portion LS1(R) and end EDG2 (an example of a "second end" in this disclosure) along the opening H2 of horizontal shading portion LS1(L) each extend in a direction that intersects obliquely with both the first direction and the second direction.

[0066] That is, the opening H1 of the pixel PX(R) and the opening H2 of the pixel PX(L) are substantially symmetrical in a plan view and have ends that are not 90° apart from the axis of symmetry, which makes it possible to simultaneously improve the charge transfer efficiency and suppress PLS (Parasitic Light Sensitivity).

[0067] The shapes of the openings H1 and H2 and their influence on charge transfer and PLS will be described in more detail. Fig. 5A is a plan view showing a horizontal light shielding portion LS' according to a comparative example of the present disclosure and an opening H' provided in the horizontal light shielding portion LS'. Fig. 5B is a plan view showing a horizontal light shielding portion LS according to an embodiment of the present disclosure and an opening H provided in the horizontal light shielding portion LS. Note that the horizontal light shielding portion LS and the opening H in Fig. 5B are schematic diagrams of one of the horizontal light shielding portions LS1(R) and LS1(L) and one of the openings H1 and H2 shown in Fig. 4E and the like.

[0068] In order to obtain a sufficient light shielding effect on the charge storage section by the light shielding section, it is important to separate the opening of the light shielding section from the light collection center of the pixel. Also, in order to suppress dark signals in general image sensors, the interface of a material other than the Si that constitutes the semiconductor substrate is made p-type and filled with holes.

[0069] In both the comparative example and the present embodiment, the n-type semiconductor region is depleted in its entirety immediately after resetting the photoelectric conversion unit. Here, when the shape of the opening H' of the horizontal light shielding portion LS' is rectangular as in the comparative example shown in FIG. 5A, the short side of the opening H' is short, so that the potential of the depletion portion of the n-type semiconductor region becomes shallow, and it becomes difficult to extend the depletion layer to the back surface. On the other hand, when the opening H of the horizontal light shielding portion LS has an oblique side as in the present embodiment shown in FIG. 5B, it is possible to secure the width of the opening H, so that the potential of the n-type semiconductor region can be increased, and it becomes possible to extend the depletion layer to the back surface. This can improve the charge transfer efficiency. It is possible to achieve both improved charge transfer efficiency and PLS suppression.

[0070] (Effects of the First Embodiment) As described above, the imaging device 101 according to the first embodiment of the present disclosure includes a semiconductor substrate 10 having a back surface 10b and a front surface 10a located on the opposite side of the back surface 10b, and a plurality of sensor pixels PX provided on the semiconductor substrate 10. Each of the plurality of sensor pixels PX includes a pixel PX(R) and a pixel PX(L) adjacent to the pixel PX(R) in a first direction parallel to the back surface 10b. The pixel PX(R) includes a photoelectric conversion unit (R) capable of generating a charge by photoelectrically converting light incident from the back surface 10b side of the semiconductor substrate 10, a charge holding unit MEM(R) provided on the opposite side of the back surface 10b across the photoelectric conversion unit (R) and capable of holding a charge transferred from the photoelectric conversion unit (R), and a horizontal light shielding unit LS1(R) provided between the back surface 10b and the charge holding unit MEM(R). The pixel PX(L) has a photoelectric conversion unit (L) capable of generating an electric charge by photoelectrically converting light incident from the back surface 10b side of the semiconductor substrate 10, a charge holding unit MEM(L) that is provided on the opposite side of the back surface 10b across the photoelectric conversion unit (L) and is capable of holding electric charges transferred from the photoelectric conversion unit (L), and a horizontal light-shielding unit LS1(L) provided between the back surface 10b and the charge holding unit MEM(L).

[0071] In a plan view from the normal direction of the back surface 10b of the semiconductor substrate 10, the opening H1 provided in the horizontal light shielding portion LS1(R) and the opening H2 provided in the horizontal light shielding portion LS1(L) are symmetrical with respect to a straight line CL that passes through the center of the sensor pixel PX and is parallel to a second direction perpendicular to the first direction. In a plan view, an end EDG1 along the opening H1 of the horizontal light shielding portion LS1(R) and an end EDG2 along the opening H2 of the horizontal light shielding portion LS1(L) each extend in a direction that obliquely intersects both the first direction and the second direction.

[0072] According to this, the horizontal light shielding portion LS1(R) and the horizontal light shielding portion LS1(L) can suppress the incidence of light to the charge holding portion MEM(R) and the charge holding portion MEM(L), so that PLS can be reduced. In addition, the opening portion H1 provided in the horizontal light shielding portion LS1(R) and the opening portion H2 provided in the horizontal light shielding portion LS1(L) are symmetrical with respect to the straight line CL passing through the center of the sensor pixel PX as the axis of symmetry. This can reduce the sensitivity difference of the incident light between the pixel PX(R) and the pixel PX(L). For example, the sensitivity difference of the obliquely incident light obliquely incident on the back surface 10b of the semiconductor substrate 10 can be reduced, and the phase difference detection ability can be improved. Furthermore, the horizontal light shielding portion LS1(R) has an oblique end portion EDG1, and the horizontal light shielding portion LS1(L) has an oblique end portion EDG2. This can improve the transfer efficiency of the charge from the photoelectric conversion portion PD(R), PD(L) to the charge holding portion MEM(R), MEM(L) and suppress the PLS at the same time. As a result, it is possible to improve the performance of the imaging device.

[0073] <Embodiment 2> In the above-described first embodiment, one stage each of the horizontal light shielding portions LS1(R) and LS1(L) is arranged in the thickness direction (depth direction) of the semiconductor substrate. However, the embodiments of the present disclosure are not limited to this. In the embodiments of the present disclosure, two or more stages of horizontal light shielding portions may be arranged alternately in the depth direction in one sensor pixel PX.

[0074] FIG. 6 is a cross-sectional view showing a configuration example of a sensor pixel PXA according to the second embodiment of the present disclosure. FIGS. 7A to 7D are plan views showing a configuration example of a sensor pixel PXA according to the second embodiment of the present disclosure. In more detail, FIG. 6 shows a cross-sectional configuration example obtained by cutting each of the plan views of FIGS. 7A to 7C along the line B1-B1' to the line B3-B3'. FIGS. 7A to 7C show planar configuration examples at each position of LV1 to LV3 in the cross-sectional view of FIG. 6. FIG. 7D shows an enlarged planar configuration example when one sensor pixel PXA is viewed from the rear surface 10b side, and more specifically, shows an enlarged view of the plan views of LV1 to LV3 shown in FIGS. 7A to 7C superimposed on each other.

[0075] 6 to 7D, each of the multiple sensor pixels PXA has a pixel PX(R) and a pixel PX(L) similar to the pixel PX according to embodiment 1. The pixels PX(R) and PX(L) are adjacent to each other in a first direction (for example, the left-right direction on the paper of each of FIGS. 6 to 7D).

[0076] In addition to the horizontal light-shielding portion LS1(R), the pixel PX(R) has a horizontal light-shielding portion LS2(R) (an example of a "third light-shielding portion" in the present disclosure) that is arranged alternately with the horizontal light-shielding portion LS1(R) in the depth direction. The horizontal light-shielding portion LS2(R) is provided between the rear surface 10b of the semiconductor substrate 10 and the charge retention portion MEM(R) and is closer to the front surface 10a of the semiconductor substrate 10 than the horizontal light-shielding portion LS1(R). As shown in FIG. 7D, in the pixel PX(R), there is an overlapping region OVL(R) where the horizontal light-shielding portion LS1(R) and the horizontal light-shielding portion LS2(R) overlap in the depth direction.

[0077] Similarly, the pixel PX(L) has, in addition to the horizontal light-shielding portion LS1(L), a horizontal light-shielding portion LS2(L) (an example of a "fourth light-shielding portion" in the present disclosure) that is arranged alternately with the horizontal light-shielding portion LS1(L) in the depth direction. The horizontal light-shielding portion LS2(L) is provided between the rear surface 10b of the semiconductor substrate 10 and the charge retention portion MEM(L) and closer to the front surface 10a of the semiconductor substrate 10 than the horizontal light-shielding portion LS1(L). As shown in FIG. 7D, in the pixel PX(L), there is an overlapping region OVL(L) where the horizontal light-shielding portion LS1(L) and the horizontal light-shielding portion LS2(L) overlap in the depth direction.

[0078] As shown in FIG. 6, the horizontal light shielding portions LS2(R) and LS2(L) are provided parallel to the back surface 10b of the semiconductor substrate 10, which is the light incident surface, and at the same depth from the back surface 10b.

[0079] 6 and 7A, the horizontal light shielding portion LS2(R) is provided with an opening H3 (an example of the "third opening" in this disclosure) penetrating the horizontal light shielding portion LS2(R). The horizontal light shielding portion LS2(L) is provided with an opening H4 (an example of the "fourth opening" in this disclosure) penetrating the horizontal light shielding portion LS2(L).

[0080] In a planar view, the opening H3 provided in the horizontal light shielding portion LS2(R) and the opening H4 provided in the horizontal light shielding portion LS2(L) are symmetrical with respect to a straight line CL that passes through the center of the sensor pixel PXA and is parallel to the second direction (for example, the up-down direction of each of the pages of Figures 7A to 7D).

[0081] In a planar view, the end EDG2(R) along the opening H3 of the horizontal shading portion LS2(R) and the end EDG2(L) along the opening H4 of the horizontal shading portion LS2(L) each extend in a direction that obliquely intersects both the first direction and the second direction.

[0082] The openings H3 provided in the horizontal light shielding portion LS2(R) and the openings H1 provided in the horizontal light shielding portion LS1(R) are arranged alternately in the thickness direction (depth direction) of the semiconductor substrate 10. Similarly, the openings H4 provided in the horizontal light shielding portion LS2(L) and the openings H2 provided in the horizontal light shielding portion LS1(L) are arranged alternately in the depth direction.

[0083] As shown in FIGS. 6 and 7A, horizontal light shielding portion LS2(R) and horizontal light shielding portion LS2(L) are formed integrally with second inter-pixel isolation portion 32 which is a part of inter-pixel isolation portion 30. As shown in FIG.

[0084] As shown in Fig. 6 and Fig. 7C, the horizontal light shielding portion LS1(R) and the horizontal light shielding portion LS1(L) are formed integrally with the first intra-pixel isolation portion 21, which is a part of the intra-pixel isolation portion 20. For example, as shown in Fig. 7D, in the second direction (the vertical direction of the paper surface of Fig. 7D), if the length of the first intra-pixel isolation portion 21 is L1 and the length of the second intra-pixel isolation portion 22 is L2, the length L1 is longer than the length L2 (L1>L2). The horizontal light shielding portion LS1(R) and the horizontal light shielding portion LS1(L), which are closer to the charge retention portions MEM(R) and MEM(L) than the horizontal light shielding portion LS2(R) and the horizontal light shielding portion LS2(L), are formed integrally with the first intra-pixel isolation portion 21, which is longer in the second direction than the second intra-pixel isolation portion 22.

[0085] (Effects of the second embodiment) As described above, in the sensor pixel PXA according to the second embodiment, the pixel PX(R) further includes a horizontal light-shielding portion LS2(R) provided between the rear surface 10b and the charge storage portion MEM(R) and closer to the rear surface 10b than the horizontal light-shielding portion LS1(R). The pixel PX(L) further includes a horizontal light-shielding portion LS2(L) provided between the rear surface 10b and the charge storage portion MEM(L) and closer to the rear surface 10b than the horizontal light-shielding portion LS1(L).

[0086] According to this, the horizontal light shielding portion LS2(R) and the horizontal light shielding portion LS2(L) can further suppress the incidence of light on the charge holding portion MEM(R) and the charge holding portion MEM(L), thereby further improving the light shielding ability for the charge holding portions MEM(R) and (L).

[0087] In addition, in the thickness direction (depth direction) of the semiconductor substrate 10, the openings H1 of the horizontal light shielding portion LS1(R1) and the openings H3 of the horizontal light shielding portion LS2(R) are arranged alternately, and the openings H2 of the horizontal light shielding portion LS1(L1) and the openings H4 of the horizontal light shielding portion LS2(L) are also arranged alternately. This makes it possible to bypass the optical path from the rear surface 10b of the semiconductor substrate 10 to the charge holding portions MEM(R),(L), and thus to extend the optical path length to the charge holding portions MEM(R),(L). This makes it possible to further improve the light shielding ability for the charge holding portions MEM(R),(L).

[0088] Furthermore, the horizontal light-shielding portions LS1(R), LS1(L) located closest to the front surface 10a of the semiconductor substrate 10 are integrally formed with the first intra-pixel isolation portion 21, which is the longest among the intra-pixel isolation portions 20 located on the straight line CL (i.e., the axis of symmetry) passing through the center of the sensor pixel PX. This makes it possible to further extend the optical path length from the rear surface 10b of the semiconductor substrate 10 to the charge retention portions MEM(R),(L). This makes it possible to further improve the light-shielding ability for the charge retention portions MEM(R),(L).

[0089] (Modification of the second embodiment) (1) Variation 1 Fig. 8 is a cross-sectional view showing a configuration of a sensor pixel PXB according to Modification 1 of Embodiment 2 of the present disclosure. Fig. 9 is a plan view showing a configuration of a sensor pixel PXB according to Modification 1 of Embodiment 2 of the present disclosure. To explain in detail, Fig. 8 shows a cross-sectional configuration obtained by cutting the plan view of Fig. 9 along line C1-C1'. Fig. 9 shows a planar configuration of four sensor pixels PXB when viewed from the rear surface 10b side, and more specifically, shows horizontal light shielding portions LS1(R) and LS2(R) and horizontal light shielding portions LS1(L) and LS2(L) that are alternately arranged in the thickness direction (depth direction) of the semiconductor substrate 10, superimposed on each other.

[0090] The sensor pixel PXB shown in Figures 8 and 9 is different from the sensor pixel PXA shown in Figures 6 to 7D in that the space S20 provided in the intra-pixel isolation portion 20 is wider. As shown in Figure 9, for example, if the width of the space S20 in the second direction (the vertical direction on the paper surface of Figure 7) is WS20 and the width of the space S30 in the second direction is WS30, the width WS20 is wider than the width WS30 (WS20>WS30). Even if the width of the space S30 in the first direction (the horizontal direction on the paper surface of Figure 7) is WS30, WS20>WS30.

[0091] In this example, the intra-pixel separation section 20 is constituted by only the first intra-pixel separation section 21, and the second intra-pixel separation section 22 is not disposed, so that the space S20 of the intra-pixel separation section 20 is formed to be wide.

[0092] The sensor pixel PXB according to the first modification example makes it easy to form the overflow path 23 in the space S20 of the intra-pixel isolation unit 20. Even if charges are saturated in one of the photoelectric conversion units PD(R), PD(L), charges can be moved from one of the photoelectric conversion units PD(R) and PD(L) to the other via the overflow path 23. Signal charges can be stored using the capacitances of both the photoelectric conversion units PD(R) and PD(L), which contributes to an expansion of the dynamic range.

[0093] (2) Variation 2 Fig. 10 is a cross-sectional view showing a configuration of a sensor pixel PXC according to Modification 2 of Embodiment 2 of the present disclosure. Fig. 11 is a plan view showing a configuration of a sensor pixel PXC according to Modification 2 of Embodiment 2 of the present disclosure. To explain in detail, Fig. 10 shows a cross-sectional configuration obtained by cutting the plan view of Fig. 11 along line D1-D1'. Fig. 11 shows a planar configuration of four sensor pixels PXC when viewed from the rear surface 10b side, and more specifically, shows horizontal light shielding portions LS1(R) and LS2(R) and horizontal light shielding portions LS1(L) and LS2(L) that are alternately arranged in the thickness direction (depth direction) of the semiconductor substrate 10, superimposed on each other.

[0094] 10 and 11 is different from the sensor pixel PXA shown in Fig. 6 to Fig. 7D in that the first metal film 61 is not embedded in the intra-pixel isolation portion 20 on the side closer to the back surface 10b (i.e., the light incident surface) than the horizontal light shielding portions LS1(R), LS1(L) (hereinafter also referred to as the light incident surface side). The portion of the intra-pixel isolation portion 20 on the light incident surface side is composed of a first trench 51 and an insulating film 55 embedded in the first trench 51.

[0095] In addition, the portion of the intra-pixel isolation portion 20 that is closer to the surface 10a than the horizontal light-shielding portions LS1(R) and LS1(L) is composed of a first trench 51, an insulating film 55 provided in the first trench 51, and a first metal film 61 provided in the first trench 51 via the insulating film 55, similar to the sensor pixel PXA shown in Figures 6 to 7D.

[0096] In the sensor pixel PXC according to the second modification, the first metal film 61 is not embedded in the portion of the intra-pixel separation unit 20 on the light incident surface side, so that it is possible to prevent the incident light from being reflected on the surface of the first metal film 61 or being absorbed by the first metal film 61. In particular, the end portion on the light incident surface side of the intra-pixel separation unit 20 tends to strongly reflect the incident light, but since there is no first metal film 61 in this portion, it is possible to effectively suppress the reflection and absorption of the incident light. This can be expected to improve sensitivity by suppressing absorption of the incident light, and to suppress flare by reducing the reflectance of the incident light.

[0097] 11, in the second modification, the space S20 provided in the intra-pixel separation unit 20 may be made wider, as in the first modification. For example, the intra-pixel separation unit 20 may be composed of only the first intra-pixel separation unit 21, without providing the second intra-pixel separation unit 22, thereby making it possible to form the space S20 of the intra-pixel separation unit 20 wider. This allows charge to move via the overflow path 23, as in the first modification.

[0098] (3) Variation 3 Fig. 12 is a cross-sectional view showing a configuration of a sensor pixel PXD according to Modification 3 of Embodiment 2 of the present disclosure. Fig. 13 is a plan view showing a configuration of a sensor pixel PXD according to Modification 3 of Embodiment 2 of the present disclosure. To explain in detail, Fig. 12 shows a cross-sectional configuration obtained by cutting the plan view of Fig. 13 along line E1-E1'. Fig. 13 shows a planar configuration of four sensor pixels PXDs when viewed from the rear surface 10b side, and more specifically, shows horizontal light shielding portions LS1(R) and LS2(R) and horizontal light shielding portions LS1(L) and LS2(L) that are alternately arranged in the thickness direction (depth direction) of the semiconductor substrate 10, superimposed on each other.

[0099] 12 and 13, the first difference from the sensor pixel PXA shown in Figures 6 to 7D is that the first metal film 61 is not embedded in the entire portion extending from the back surface 10b to the front surface 10a of the intra-pixel isolation portion 20. The intra-pixel isolation portion 20 is composed of a first trench 51 and an insulating film 55 embedded in the first trench 51.

[0100] The second difference is that the intra-pixel separation portion 20 is formed to be narrower than the inter-pixel separation portion 30. As shown in FIG. 13, in a plan view, the intra-pixel separation portion 20 has a narrower line width than the inter-pixel separation portion 30. If the line width of the intra-pixel separation portion 20 is W20 and the line width of the inter-pixel separation portion 30 is W30, then W20 <W30である。

[0101] In the sensor pixel PXD according to the third modification, the first metal film 61 is not embedded in the intra-pixel separation portion 20, and therefore it is possible to prevent the incident light from being reflected on the surface of the first metal film 61 or absorbed by the first metal film 61. This can be expected to improve sensitivity by suppressing absorption of the incident light, and to suppress flare by reducing the reflectance of the incident light.

[0102] Furthermore, since the intra-pixel isolation portion 20 is formed narrower than the inter-pixel isolation portion 30, it is easy to fill the intra-pixel isolation portion 20 with the insulating film 55. Furthermore, it is possible to simultaneously form the insulating film 56 of the inter-pixel isolation portion 30 and the insulating film of the intra-pixel isolation portion 20 in the same process. For example, when the insulating film 56 of the inter-pixel isolation portion 30 and the insulating film 55 of the intra-pixel isolation portion 20 are simultaneously formed by atomic layer deposition (ALD), it is possible to first close only the first trench 51 of the intra-pixel isolation portion 20 with the insulating film 55 before closing the second trench 53 of the inter-pixel isolation portion 30 with the insulating film 56.

[0103] 13, in the third modification, the space S20 provided in the intra-pixel separation unit 20 may be made wider, as in the first modification. For example, the intra-pixel separation unit 20 may be composed of only the first intra-pixel separation unit 21, without providing the second intra-pixel separation unit 22, thereby making it possible to form the space S20 of the intra-pixel separation unit 20 wider. This allows charge to move via the overflow path 23, as in the first modification.

[0104] (4) Variation 4 Fig. 14 is a cross-sectional view showing a configuration of a sensor pixel PXE according to Modification 4 of Embodiment 2 of the present disclosure. The first difference between the sensor pixel PXE shown in Fig. 14 and the sensor pixel PXA shown in Fig. 6 to Fig. 7D is that the first trench 51 constituting the intra-pixel isolation section 20 is not provided on the side closer to the back surface 10b than the horizontal light shielding sections LS1(R) and LS1(L) (i.e., the light incident surface side), and the insulating film 55 and the first metal film 61 embedded in the first trench 51 are not provided either. The portion of the intra-pixel isolation section 20 on the light incident surface side is composed of only the p-type region 12.

[0105] The second difference is that the second trench 53 constituting the inter-pixel isolation section 30 is not provided on the side closer to the back surface 10b than the horizontal light-shielding sections LS2(R), LS2(L) (i.e., the light incident surface side), and the insulating film 56 and the second metal film 62 embedded in the second trench 53 are not provided either. The portion of the inter-pixel isolation section 30 on the light incident surface side is also composed of only the p-type region 12.

[0106] In the sensor pixel PXE according to the second modification, the first metal film 61 is not embedded in the portion of the intra-pixel separation unit 20 on the light incident surface side, so that it is possible to prevent the incident light from being reflected on the surface of the first metal film 61 or being absorbed by the first metal film 61. Moreover, not only in the intra-pixel separation unit 20 but also in the inter-pixel separation unit 30, the second metal film 62 is not embedded in the portion on the light incident surface side, so that it is possible to prevent the incident light from being reflected on the surface of the second metal film 62 or being absorbed by the second metal film 62. This can be expected to improve sensitivity by suppressing absorption of the incident light and to further suppress flare by reducing the reflectance of the incident light.

[0107] Furthermore, the first trench 51 is not provided in the portion of the intra-pixel isolation section 20 on the light incident surface side. This allows an overflow path 23 to be provided in the portion of the intra-pixel isolation section 20 on the light incident surface side, as shown in Fig. 14. The overflow path 23 is, for example, an n-type In the portion on the light incident surface side, charge can move via an overflow path 23.

[0108] (Variation 5) Figures 15A and 15B are cross-sectional views showing the configuration of a sensor pixel PXF according to Modification 5 of Embodiment 2 of the present disclosure. Figures 16A to 16E are plan views showing the configuration of a sensor pixel PXF according to Modification 5 of Embodiment 2 of the present disclosure. To explain in detail, Figure 15A shows a cross-sectional configuration obtained by cutting each of the plan views of Figures 16A to 16E along lines FA1-FA1' to FA5-FA5'. Figures 16A to 16E show planar configurations at each position from LV1 to LV5 in each of the cross-sectional views of Figures 15A and 15.

[0109] The difference between the sensor pixel PXF shown in Figures 15A to 16E and the sensor pixel PXA shown in Figures 6 to 7D is that the trench constituting the inter-pixel isolation portion 30 is provided deep from the front surface 10a to the back surface 10b of the semiconductor substrate 10, whereas the trench constituting the intra-pixel isolation portion 20 is not provided from the front surface 10a to the back surface 10b of the semiconductor substrate 10, and is not dug deep.

[0110] A more detailed description will be given. The inter-pixel isolation portion 30 has a first inter-pixel isolation portion 31 and a second inter-pixel isolation portion 32. The first inter-pixel isolation portion 31 has a first trench 51, an insulating film 55 provided in the first trench 51, and a first metal film 61 embedded in the first trench 51 via the insulating film 55. The second inter-pixel isolation portion 32 has a second trench 53, an insulating film 56 provided in the second trench 53, and a second metal film 62 embedded in the second trench 53 via the insulating film 56. Between the first inter-pixel isolation portion 31 and the second inter-pixel isolation portion 32, a space S30 constituted by, for example, a p-type region 12 is interposed.

[0111] Moreover, the intra-pixel isolation portion 20 has a first intra-pixel isolation portion 21 and a second intra-pixel isolation portion 22. The first intra-pixel isolation portion 21 has a first trench 51, an insulating film 55 provided in the first trench 51, and a first metal film 61 embedded in the first trench 51 with the insulating film 55 interposed therebetween. The second intra-pixel isolation portion 22 has a second trench 53, an insulating film 56 provided in the second trench 53, and a second metal film 62 embedded in the second trench 53 with the insulating film 56 interposed therebetween. Between the first intra-pixel isolation portion 21 and the second intra-pixel isolation portion 22, a space S20 constituted by, for example, a p-type region 12 is interposed.

[0112] In the sensor pixel PXF, both the first trench 51 (hereinafter, first trench 51B; an example of the "first trench B" in the present disclosure) constituting the first inter-pixel isolation portion 31 and the second trench 53 (hereinafter, second trench 53B) constituting the second inter-pixel isolation portion 32 are provided deep from the front surface 10a to the back surface 10b of the semiconductor substrate 10. As a result, the first metal film 61 in the first trench 51B and the second metal film 62 in the second trench 53B are also provided from the front surface 10a to the back surface 10b of the semiconductor substrate 10.

[0113] In contrast, the first trench 51 (hereinafter, the first trench 51A; an example of the "first trench A" in the present disclosure) constituting the first intra-pixel isolation portion 21 and the second trench 53 (hereinafter, the second trench 53A) constituting the second intra-pixel isolation portion 22 are provided from the front surface 10a of the semiconductor substrate 10 to the positions of the horizontal light-shielding portions LS1(R), (L). The first trench 51A and the second trench 53A are not deeply excavated like the first trench 51B and the second trench 53B, and are not provided between the horizontal light-shielding portions LS1(R), (L) and the rear surface 10b. The first trench 51A, the first metal film 61 in the first trench 51A, and the second metal film 62 in the second trench 53A do not reach the rear surface 10b.

[0114] In the first intra-pixel isolation portion 21, a portion between the positions of the horizontal light-shielding portions LS1(R), (L) and the back surface 10b is composed of, for example, a p-type region 12. Similarly, in the second intra-pixel isolation portion 22, a portion between the positions of the horizontal light-shielding portions LS1(R), (L) and the back surface 10b is composed of, for example, a p-type region 12.

[0115] In the sensor pixel PXF, the first intra-pixel isolation portion 21 and the first inter-pixel isolation portion 31 are also formed integrally, but the depths of their trenches are different. The trench is formed deeper in the first inter-pixel isolation portion 31 than in the first intra-pixel isolation portion 21. Similarly, the second intra-pixel isolation portion 22 and the second inter-pixel isolation portion 32 are also formed integrally, but the depths of their trenches are different. The trench is formed deeper in the second inter-pixel isolation portion 32 than in the second intra-pixel isolation portion 22.

[0116] The sensor pixel PXF according to the fifth modification has the above-described structure, and thus can reduce electrical and optical crosstalk while suppressing scattering and reflection of light.

[0117] (Variation 6) (1) Composition FIG. 17 is a cross-sectional view showing a configuration of a sensor pixel PXG according to Modification 6 of the embodiment 2 of the present disclosure. FIGS. 18A and 18B are plan views showing a configuration of a sensor pixel PXG according to Modification 6 of the embodiment 2 of the present disclosure. To explain in detail, FIG. 17 shows a cross-sectional configuration obtained by cutting each of the plan views of FIGS. 18A and 18B along lines GB1-GB1' and GB5-GB5'. FIGS. 18A and 18B show plan configurations at positions LV1 and LV5 of the cross-sectional view of FIG. 17. Note that the plan configurations at positions LV2 to LV4 of the cross-sectional view of FIG. 17 are the same as the plan configurations shown in FIGS. 16B to 16D, and therefore repeated illustrations are omitted. Also, the cross-sectional configurations obtained by cutting each of the plan views of FIGS. 18A and 18B along lines GA1-GA1' and GA5-GA5' are the same as the cross-sectional configuration shown in FIG. 15A, and therefore repeated illustrations are omitted.

[0118] The sensor pixel PXG shown in Figures 17A to 18B is different from the sensor pixel PXF shown in Figures 15A to 16E in that the first intra-pixel isolation portion 21 and the first inter-pixel isolation portion 31 are not directly connected to each other, but are connected to each other via horizontal light-shielding portions LS1(R) and LS1(L). In the sensor pixel PXG, the first trench 51A constituting the first intra-pixel isolation portion 21 and the first trench 51B constituting the first inter-pixel isolation portion 31 are not integrated. The first trench 51A and the first trench 51B are connected (communicated) to each other via a space portion 52 constituting the horizontal light-shielding portions LS1(R) and LS1(L). A first metal film 61 is embedded in the first trenches 51A and 51B connected to the space portion 52 via the second trench via an insulating film 55.

[0119] In the first intra-pixel isolation portion 21, the first trench 51A is not provided between the positions of the horizontal light-shielding portions LS1(R), (L) and the back surface 10b. In the first intra-pixel isolation portion 21, the portion between the positions of the horizontal light-shielding portions LS1(R), (L) and the back surface 10b is configured with, for example, a p-type region 12.

[0120] The sensor pixel PXG according to the sixth modification, like the sensor pixel PXF according to the fifth modification, can reduce electrical and optical crosstalk while suppressing scattering and reflection of light.

[0121] (2) Manufacturing method 19 is a cross-sectional view showing a process sequence of a trench formation method suitable for the sixth modification of the second embodiment of the present disclosure. In step ST1 of FIG. 19, a semiconductor substrate 10 on which photoelectric conversion units PD(R), PD(L) (see FIG. 18A) (not shown) are formed is prepared. Next, a hard mask (not shown) is formed on the front surface 10a (the lower surface in FIG. 19) of the semiconductor substrate 10. The hard mask is made of an insulating material such as a silicon nitride film (SiN film) or a silicon oxide film (SiO film).

[0122] Next, the surface 10a of the semiconductor substrate 10 is partially dug down by dry etching using a hard mask to form a trench T1. The depth of the trench T1 at this time corresponds to the depth of the first trench shown in FIG.

[0123] Next, a sidewall SW is formed to cover the side and bottom surfaces of the trench T1. When forming the sidewall SW, an insulating film made of, for example, a SiN film or a SiO film is formed to cover the inner surface of the trench T1, i.e., the side and bottom surfaces of the trench T1, and then only the insulating film covering the bottom surface of the trench T1 is removed by dry etchback.

[0124] 19, the semiconductor substrate 10 is partially removed by dry etch-back so as to further dig down the bottom surface of the trench T1. At that time, the bottom surface of the trench T1 is further dug down by an amount corresponding to the thickness of the horizontal light-shielding portions LS1(R) and LS2(L) (see FIGS. 17 and 16D), for example.

[0125] Next, a specific alkaline aqueous solution is injected into the trench T1, and wet etching is performed to remove a portion of the Si(111) surface constituting the semiconductor substrate 10. As the alkaline aqueous solution, inorganic solutions such as KOH, NaOH, and CsOH can be used, and organic solutions such as EDP (ethylenediaminepyrocatechol aqueous solution), N2H4 (hydrazine), NH4OH (ammonium hydroxide), and TMAH (tetramethylammonium hydroxide) can be used.

[0126] Here, we perform anisotropic etching, which utilizes the property that the etching rate varies depending on the surface orientation of Si(111). Specifically, for a Si(111) substrate, <111> With respect to the etching rate in the direction, i.e., the direction with three Si back bonds <110> The etching rate in the direction, i.e., the direction having one or two Si back bonds, becomes sufficiently high.

[0127] Therefore, in this embodiment, etching proceeds in the X-axis direction, while etching hardly proceeds in the Y-axis and Z-axis directions. As a result, a space T2 communicating with trench T1 is formed inside semiconductor substrate 10, which is a Si(111) substrate. This space T2 becomes space 52 (see FIG. 17) in which horizontal light shielding portions LS1(R) and LS2(L) (see FIG. 17 and FIG. 16D) are disposed. <110> The distance of etching in the direction can be adjusted by the etching treatment time for the semiconductor substrate 10 with the alkaline aqueous solution.

[0128] Next, as shown in step ST3 of FIG. 19, photoresist is embedded in the trenches that will become the first trenches 51A (see FIG. 17) among the multiple trenches T1. Then, as shown in step ST4 of FIG. 19, the surface 10a of the semiconductor substrate 10 is partially further dug down by dry etching using the photoresist to form a trench T3. This trench T3 becomes the deeply dug first trench 51B and second trench 53A shown in FIG. 17. After the trench T3 is formed, the photoresist PR is removed, and then the sidewalls SW are removed. Through these steps, a trench suitable for the sixth modification is formed.

[0129] <Applications to electronic devices> The technology according to the present disclosure (the present technology) can be applied to electronic devices. Fig. 20 is a diagram showing a configuration example of an electronic device 600 to which the present technology can be applied. As shown in Fig. 20, the electronic device 600 includes a solid-state imaging device 601, an optical lens 602, a shutter device 603, a driving circuit 604, and a signal processing circuit 605. The electronic device 600 is, for example, an electronic device such as a camera.

[0130] The electronic device 600 includes an imaging device 101 having one or more of the sensor pixels PX, PXA, PXB, PXC, PXD, PXE, PXF, and PXG shown in Figures 3, 6, 8, 10, 12, 14, 15A, 15B, 17, etc. as a solid-state imaging device 601. This allows the solid-state imaging device 601 to achieve both improved charge transfer efficiency and PLS suppression, thereby improving performance.

[0131] The optical lens 602 focuses image light (incident light 606) from a subject on the imaging surface of the solid-state imaging device 601. As a result, signal charges are accumulated in the solid-state imaging device 601 for a certain period of time. The shutter device 603 controls the light irradiation period and light blocking period of the solid-state imaging device 601. The drive circuit 604 supplies a drive signal that controls the transfer operation of the solid-state imaging device 601 and the shutter operation of the shutter device 603. The drive signal (timing signal) supplied from the drive circuit 604 transfers signals from the solid-state imaging device 601. The signal processing circuit 605 performs various signal processing on signals (pixel signals) output from the solid-state imaging device 601. The video signal that has undergone signal processing is stored in a storage medium such as a memory, or output to a monitor.

[0132] The electronic device 600 is not limited to a camera, and may be another electronic device, for example, an imaging device such as a camera module for a mobile device such as a mobile phone.

[0133] <Applications to moving objects> The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility device, an airplane, a drone, a ship, a robot, etc.

[0134] FIG. 21 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a moving object control system to which the technology according to the present disclosure can be applied.

[0135] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 21, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also, as functional configurations of the integrated control unit 12050, a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053 are illustrated.

[0136] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0137] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as head lamps, back lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves or signals of various switches transmitted from a portable device that replaces a key may be input to the body system control unit 12020. The body system control unit 12020 receives the input of these radio waves or signals and controls the door lock device, power window device, lamps, and the like of the vehicle.

[0138] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture an image outside the vehicle and receives the captured image. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for a person, a car, an obstacle, a sign, or characters on a road surface, based on the received image.

[0139] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal according to the amount of light received. The imaging unit 12031 can output the electrical signal as an image, or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0140] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing.

[0141] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, the steering mechanism, or the braking device based on the information inside and outside the vehicle acquired by the outside-of-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output a control command to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0142] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on the driver's operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle acquired by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0143] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside-vehicle information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside-vehicle information detection unit 12030, and perform cooperative control for the purpose of preventing glare, such as switching from high beams to low beams.

[0144] The audio / video output unit 12052 transmits at least one output signal of audio and video to an output device capable of visually or audibly notifying information to passengers in the vehicle or the outside of the vehicle. In the example of Fig. 21, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as the output device. The display unit 12062 may include at least one of an on-board display and a head-up display, for example.

[0145] FIG. 22 is a diagram showing an example of the installation position of the imaging unit 12031.

[0146] In FIG. 22, a vehicle 12100 has imaging units 12101, 12102, 12103, 12104, and 12105 as an imaging unit 12031.

[0147] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided at positions such as the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided at the front nose and the imaging unit 12105 provided at the upper part of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided at the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided at the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The images of the front acquired by the imaging units 12101 and 12105 are mainly used to detect a preceding vehicle, a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.

[0148] 22 shows an example of the imaging ranges of the imaging units 12101 to 12104. An imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and an imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, an overhead image of the vehicle 12100 viewed from above is obtained by superimposing the image data captured by the imaging units 12101 to 12104.

[0149] At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera made up of a plurality of imaging elements, or may be an imaging element having pixels for detecting a phase difference.

[0150] For example, the microcomputer 12051 can extract, as a preceding vehicle, a three-dimensional object that is the closest three-dimensional object on the travel path of the vehicle 12100 and travels at a predetermined speed (for example, 0 km / h or more) in approximately the same direction as the vehicle 12100, by calculating the distance to each three-dimensional object in the imaging ranges 12111 to 12114 and the change over time of this distance (relative speed with respect to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104. Furthermore, the microcomputer 12051 can set a vehicle distance to be secured in advance in front of the preceding vehicle, and perform automatic brake control (including follow-up stop control) and automatic acceleration control (including follow-up start control). In this way, cooperative control can be performed for the purpose of automatic driving that travels autonomously without relying on the driver's operation.

[0151] For example, the microcomputer 12051 classifies and extracts three-dimensional object data on three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. Then, the microcomputer 12051 determines a collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0152] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether or not a pedestrian is present in the captured images of the imaging units 12101 to 12104. The recognition of such a pedestrian is performed, for example, by a procedure of extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras, and a procedure of performing pattern matching processing on a series of feature points that indicate the contour of an object to determine whether or not the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating a pedestrian at a desired position.

[0153] An example of a vehicle control system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to the imaging unit 12031 and the like among the configurations described above. Specifically, the imaging device 101 having one or more of the sensor pixels PX, PXA, PXB, PXC, PXD, PXE, PXF, and PXG shown in the above-mentioned FIGS. 3, 6, 8, 10, 12, 14, 15A, 15B, 17, and the like can be applied to the imaging unit 12031. By applying the technology according to the present disclosure to the imaging unit 12031, a captured image that is easier to see can be obtained, thereby reducing the driver's fatigue.

[0154] <Other embodiments> As described above, the present disclosure has been described by the embodiments, modifications, and application examples, but the descriptions and drawings forming part of this disclosure should not be understood as limiting the present disclosure. From this disclosure, various alternative embodiments, examples, and operation techniques will become apparent to those skilled in the art. Of course, the present technology includes various embodiments not described here. At least one of various omissions, substitutions, and modifications of components can be made within the scope of the gist of the above-mentioned embodiments and modifications. In addition, the effects described in this specification are merely examples and are not limited, and other effects may be present.

[0155] The present disclosure can also be configured as follows. (1) a semiconductor substrate having a first surface and a second surface opposite the first surface; a plurality of sensor pixels provided on the semiconductor substrate; Each of the plurality of sensor pixels includes A first pixel; a second pixel adjacent to the first pixel in a first direction parallel to the first surface, The first pixel is a first photoelectric conversion unit capable of generating charges by photoelectrically converting light incident from the first surface side; a first charge holding section that is provided on the opposite side of the first surface with the first photoelectric conversion section in between and is capable of holding the charge transferred from the first photoelectric conversion section; a first light-shielding portion provided between the first surface and the first charge retention portion; The second pixel is A second photoelectric conversion unit capable of generating charges by photoelectrically converting light incident from the first surface side; a second charge holding section that is provided on the opposite side of the first surface with the second photoelectric conversion section in between and is capable of holding the charge transferred from the second photoelectric conversion section; a second light-shielding portion provided between the first surface and the second charge retention portion, a first opening provided in the first light-shielding portion and a second opening provided in the second light-shielding portion are line-symmetric with respect to a line that passes through a center of the sensor pixel and is parallel to a second direction orthogonal to the first direction, in a plan view from a normal direction of the first surface; A light detection device, wherein, in the planar view, a first end portion of the first light-shielding portion extending along the first opening and a second end portion of the second light-shielding portion extending along the second opening each extend in a direction that obliquely intersects both the first direction and the second direction. (2) The photodetector according to (1), wherein the first light-shielding portion and the second light-shielding portion are provided parallel to the first surface and at the same depth from the first surface. (3) Each of the plurality of sensor pixels includes The photodetector according to (1) or (2), further comprising an intra-pixel separator disposed between the first pixel and the second pixel at a position overlapping with the axis of symmetry. (4) The pixel isolation portion is A first intra-pixel isolation portion; a second intra-pixel isolation portion facing the first intra-pixel isolation portion in the second direction, The photodetector according to (3), wherein a first space communicating with the first pixel and the second pixel is provided between the first intra-pixel isolation portion and the second intra-pixel isolation portion. (5) The photodetector according to (4), wherein a length of the first intra-pixel separation portion in the second direction is longer than a length of the second intra-pixel separation portion in the second direction. (6) If a direction from one of the first surface and the second surface to the other is defined as a thickness direction of the semiconductor substrate, The first intra-pixel isolation portion is A first trench provided in the thickness direction of the semiconductor substrate; The photodetector according to (4) or (5), further comprising a first metal film provided in the first trench via an insulating film. (7) The optical detection device described in (6), wherein in the thickness direction, the first trench is provided between the second surface and the first light-shielding portion and the second light-shielding portion, and is not provided between the first light-shielding portion and the second light-shielding portion and the first surface. (8) The photodetector according to any one of (4) to (7), wherein the first light-shielding portion and the second light-shielding portion are each formed integrally with the first intra-pixel isolation portion. (9) an inter-pixel separator provided on the semiconductor substrate and disposed between adjacent ones of the plurality of sensor pixels; a second space communicating between the one sensor pixel and the other sensor pixel is provided in the inter-pixel separation portion, The light detection device according to any one of (4) to (8), wherein the first space is wider than the second space in the plan view. (10) The first pixel is a third light-shielding portion provided between the first surface and the first charge retention portion and closer to the first surface than the first light-shielding portion; The second pixel is The photodetection device described in any one of (1) to (9), further comprising a fourth light-shielding portion provided between the first surface and the second charge retention portion and at a position closer to the first surface than the second light-shielding portion. (11) The light detection device according to (10), wherein the third light-shielding portion and the fourth light-shielding portion are provided parallel to the first surface and at the same depth from the first surface. (12) a third opening provided in the third light-shielding portion and a fourth opening provided in the fourth light-shielding portion are line-symmetric with respect to the straight line as an axis of symmetry in the plan view; The optical detection device described in (10) or (11), wherein, in the planar view, a third end portion of the third light-shielding portion along the third opening and a fourth end portion of the fourth light-shielding portion along the fourth opening each extend in a direction that obliquely intersects both the first direction and the second direction. (13) If a direction from one of the first surface and the second surface to the other is defined as a thickness direction of the semiconductor substrate, The first openings and the third openings are arranged alternately in the thickness direction, The light detection device according to (12), wherein the second opening and the fourth opening are arranged at different positions in the thickness direction. (14) an inter-pixel separator provided on the semiconductor substrate and disposed between adjacent ones of the plurality of sensor pixels; The photodetector according to any one of (10) to (13), wherein the third light-shielding portion and the fourth light-shielding portion are formed integrally with a part of the inter-pixel isolation portion. (15) an inter-pixel separator provided on the semiconductor substrate and disposed between adjacent ones of the plurality of sensor pixels; Each of the plurality of sensor pixels includes further comprising an intra-pixel separation portion disposed between the first pixel and the second pixel at a position overlapping with the axis of symmetry, If a direction from one of the first surface and the second surface to the other is defined as a thickness direction of the semiconductor substrate, A part of the intra-pixel isolation portion and another part of the inter-pixel isolation portion are Each of the first trenches is provided in the thickness direction, the first light-shielding portion and the second light-shielding portion each have a space portion provided in a direction intersecting the thickness direction of the semiconductor substrate, the first trench included in a part of the intra-pixel isolation portion and the first trench included in another part of the inter-pixel isolation portion are in communication with each other via the space portion; The photodetector according to any one of (1) to (14), wherein a first metal film is provided in the first trench and in the space with an insulating film interposed therebetween. (16) The first trench included in a part of the intra-pixel isolation portion is referred to as a first trench A; When the first trench included in the other part of the inter-pixel isolation portion is referred to as a first trench B, In the thickness direction, the first trench A is provided between the first surface and the first light-shielding portion and the second light-shielding portion, and is not provided between the first light-shielding portion and the second light-shielding portion and the first surface; The photodetector according to (15), wherein the first trench B is provided from the first surface to the second surface. (17) The photodetector according to any one of (15) to (16), wherein, in the plan view, the intra-pixel separation portion has a line width narrower than that of the inter-pixel separation portion. (18) The photodetector according to any one of (1) to (17), wherein the first surface of the semiconductor substrate is a (111) surface. [Explanation of symbols]

[0156] 10. Semiconductor Substrate 10a surface 10b back side 11, 55, 56 Insulating film 12, 15 p-type region 13, 14 n-type region 20 Intra-pixel separation section 21 First pixel separation section 22 Second pixel separation section 23 Overflow Path 30 Inter-pixel separation section 31 First inter-pixel separation section 32 Second inter-pixel separation section 51, 51A, 51B, T1 First trench 52, T2 space 53, 53A, 53B, T3 Second trench 61 First metal film 62 Second metal film 101 Imaging device 111 Pixel array section 112 Vertical drive unit 113 Column signal processing section 114 Horizontal drive unit 115 System control section 116 pixel drive line 118 Signal Processing Section 119 Data Storage Unit 600 Electronic equipment 601 Solid-state imaging device 602 Optical Lenses 603 Shutter device 604 Drive circuit, 605 Signal Processing Circuit 606 Incident light 12000 Vehicle Control System 12001 Communication Networks 12010 Drive system control unit 12020 Body control unit 12030 External information detection unit 12030 Body control unit 12031 Imaging unit 12040 In-vehicle information detection unit 12041 Driver status detection unit 12050 Integrated Control Unit 12051 Microcomputer 12052 Audio / Video Output Unit 12061 Audio Speaker 12062 Display section 12063 Instrument Panel 12100 Vehicles 12101, 12102, 12103, 12104, 12105 Imaging unit 12111, 12112, 12113, 12114 Imaging range AMP Amplification transistor CF Color Filter CL straight line EDG1, EDG2 ends FD Charge-to-voltage converter H, H´, H1, H2, H3, H4 opening I In-vehicle network LS1(R), LS1(L), LS2(R), LS2(L) Horizontal light shielding part MEM(R), MEM(L) Charge retention section OCL On-chip lens OFG emission transistor OVL overlap area PD, PD(R), PD(L) photoelectric conversion section PR Photoresist PX(R), PX(L) pixels PX, PXA, PXB, PXC, PXD, PXE, PXF, PXG sensor pixels RST Reset transistor S20, S30 Space SEL Select transistor SW Sidewall T1, T3 trenches T2 space TG(R)A, TG(L)A, TG(R)B, TG(L)B, TG(R)C, TG(L)C transfer transistor TRG(R), TRG(L), TRX(R), TRX(L), TRZ(R), TRZ(L) Transfer gate VDD power supply VG Vertical Gate VSL vertical signal line

Claims

1. a semiconductor substrate having a first surface and a second surface opposite the first surface; a plurality of sensor pixels provided on the semiconductor substrate; Each of the plurality of sensor pixels includes A first pixel; a second pixel adjacent to the first pixel in a first direction parallel to the first surface, The first pixel is a first photoelectric conversion unit capable of generating charges by photoelectrically converting light incident from the first surface side; a first charge holding unit that is provided on the opposite side of the first surface with the first photoelectric conversion unit therebetween and is capable of holding the charge transferred from the first photoelectric conversion unit; a first light-shielding portion provided between the first surface and the first charge retention portion; The second pixel is a second photoelectric conversion unit capable of generating charges by photoelectrically converting light incident from the first surface side; a second charge holding unit that is provided on the opposite side of the first surface with the second photoelectric conversion unit therebetween and is capable of holding the charge transferred from the second photoelectric conversion unit; a second light-shielding portion provided between the first surface and the second charge retention portion, a first opening provided in the first light-shielding portion and a second opening provided in the second light-shielding portion are line-symmetric with respect to a line that passes through a center of the sensor pixel and is parallel to a second direction orthogonal to the first direction, in a plan view from a normal direction of the first surface, A light detection device, wherein, in the planar view, a first end portion of the first light-shielding portion extending along the first opening and a second end portion of the second light-shielding portion extending along the second opening each extend in a direction that obliquely intersects both the first direction and the second direction.

2. The light detection device according to claim 1 , wherein the first light-shielding portion and the second light-shielding portion are provided parallel to the first surface and at the same depth from the first surface.

3. Each of the plurality of sensor pixels includes The photodetection device according to claim 1 , further comprising an intra-pixel separator disposed between the first pixel and the second pixel at a position overlapping with the axis of symmetry.

4. The pixel isolation portion is A first intra-pixel isolation portion; a second intra-pixel isolation portion facing the first intra-pixel isolation portion in the second direction, The photodetector according to claim 3 , wherein a first space that communicates between the first pixel and the second pixel is provided between the first intra-pixel isolation portion and the second intra-pixel isolation portion.

5. The photodetector according to claim 4 , wherein a length of the first intra-pixel isolation portion in the second direction is longer than a length of the second intra-pixel isolation portion in the second direction.

6. When a direction from one of the first surface and the second surface to the other is defined as a thickness direction of the semiconductor substrate, The first intra-pixel isolation portion is a first trench provided in the thickness direction of the semiconductor substrate; 5. The photodetector according to claim 4, further comprising a first metal film provided in the first trench via an insulating film.

7. 7. The photodetector device of claim 6, wherein in the thickness direction, the first trench is provided between the second surface and the first light-shielding portion and the second light-shielding portion, and is not provided between the first light-shielding portion and the second light-shielding portion and the first surface.

8. The light-detecting device according to claim 4 , wherein the first light-shielding portion and the second light-shielding portion are each formed integrally with the first intra-pixel isolation portion.

9. an inter-pixel separator provided on the semiconductor substrate and disposed between adjacent ones of the plurality of sensor pixels; a second space communicating between the one sensor pixel and the other sensor pixel is provided in the inter-pixel separation portion, The light detection device according to claim 4 , wherein the first space is wider than the second space in the plan view.

10. The first pixel is a third light-shielding portion provided between the first surface and the first charge retention portion and closer to the first surface than the first light-shielding portion; The second pixel is The light detection device according to claim 1 , further comprising a fourth light-shielding portion provided between the first surface and the second charge holding portion and closer to the first surface than the second light-shielding portion.

11. The light detection device according to claim 10 , wherein the third light-shielding portion and the fourth light-shielding portion are provided parallel to the first surface and at the same depth from the first surface.

12. a third opening provided in the third light-shielding portion and a fourth opening provided in the fourth light-shielding portion are line-symmetric with respect to the straight line as an axis of symmetry in the plan view; The light detection device of claim 10, wherein, in the planar view, a third end portion of the third light-shielding portion extending along the third opening and a fourth end portion of the fourth light-shielding portion extending along the fourth opening each extend in a direction that obliquely intersects both the first direction and the second direction.

13. When a direction from one of the first surface and the second surface to the other is defined as a thickness direction of the semiconductor substrate, The first openings and the third openings are arranged alternately in the thickness direction, The light detection device according to claim 12 , wherein the second opening and the fourth opening are arranged at different positions in the thickness direction.

14. an inter-pixel separator provided on the semiconductor substrate and disposed between adjacent ones of the plurality of sensor pixels; The light-detecting device according to claim 10 , wherein the third light-shielding portion and the fourth light-shielding portion are formed integrally with a part of the inter-pixel isolation portion.

15. an inter-pixel separator provided on the semiconductor substrate and disposed between adjacent ones of the plurality of sensor pixels; Each of the plurality of sensor pixels includes an intra-pixel separation portion disposed between the first pixel and the second pixel and overlapping with the axis of symmetry; When a direction from one of the first surface and the second surface to the other is defined as a thickness direction of the semiconductor substrate, A part of the intra-pixel isolation portion and another part of the inter-pixel isolation portion are Each of the first trenches is provided in the thickness direction, the first light-shielding portion and the second light-shielding portion each have a space portion provided in a direction intersecting the thickness direction of the semiconductor substrate, the first trench included in a part of the intra-pixel isolation portion and the first trench included in another part of the inter-pixel isolation portion are in communication with each other via the space portion; The photodetector according to claim 1 , further comprising a first metal film provided within said first trench and said space with an insulating film interposed therebetween.

16. The first trench included in a part of the intra-pixel isolation portion is referred to as a first trench A, When the first trench included in the other part of the inter-pixel isolation portion is a first trench B, In the thickness direction, the first trench A is provided between the first surface and the first light-shielding portion and the second light-shielding portion, and is not provided between the first light-shielding portion and the second light-shielding portion and the first surface, The photodetector according to claim 15 , wherein the first trench B is provided from the first surface to the second surface.

17. The photodetector according to claim 15 , wherein the intra-pixel isolation portion has a line width narrower than that of the inter-pixel isolation portion in the plan view.

18. 2. The photodetector device of claim 1, wherein the first surface of the semiconductor substrate is a (111) surface.

Images