Photodetector

Abstract

A photodetector that comprises an amplification region that is electrically connected to a cathode and includes a PN junction that is provided in the depth direction of a semiconductor layer, a separation region that demarcates a pixel region that includes the amplification region, a hole storage region that is provided along a side surface of the separation region and is electrically connected to an anode, and a gate electrode that is laminated on the semiconductor layer via a gate insulation film in a region that is between the amplification region and the hole storage region.

Description

Technical Field

[0001] The present disclosure relates to a photodetector.

Background Art

[0002] In recent years, a single photon avalanche diode (SPAD) that operates a avalanche photodiode at a bias voltage higher than the breakdown voltage has been proposed (for example, Patent Document 1).

[0003] In the SPAD, carriers generated by photoelectric conversion can be multiplied by a high electric field PN junction region provided for each pixel. As a result, a photodetector using an SPAD has attracted attention as a device capable of detecting one photon for each pixel.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] In a photodetector using an SPAD, it is desired to further improve the detection sensitivity of light by further increasing the photon detection efficiency (PDE) of the SPAD.

[0006] Therefore, it is desirable to provide a photodetector with higher light detection sensitivity.

[0007] A photodetector according to an embodiment of the present disclosure includes a PN junction provided in the depth direction of a semiconductor layer, an amplification region electrically connected to a cathode, a separation region defining a pixel region including the amplification region, a hole accumulation region provided along a side surface of the separation region and electrically connected to an anode, and a gate electrode provided in a region between the amplification region and the hole accumulation region and laminated on the semiconductor layer via a gate insulating film.

[0008] According to a photodetector according to an embodiment of the present disclosure, there are provided an amplification region including a PN junction provided in the depth direction of a semiconductor layer, a separation region defining a pixel region including the amplification region, a hole accumulation region provided along a side surface of the separation region, and a gate electrode laminated on a semiconductor layer in a region between the amplification region and the hole accumulation region. Thereby, the photodetector can reflect incident light that attempts to pass through the semiconductor layer with the gate electrode and return it to the semiconductor layer.

Brief Description of the Drawings

[0009]

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Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments in the present disclosure will be described in detail with reference to the drawings. The embodiments described below are a specific example of the present disclosure, and the technology according to the present disclosure is not limited to the following aspects. Also, regarding the arrangement, dimensions, dimensional ratios, etc. of each component of the present disclosure, they are not limited to the states shown in each figure.

[0011] Note that the description will be made in the following order. 1. Embodiment 1.1. Configuration example 1.2. Operation example 1.3. Modification 2. Application example

[0012] <1. Embodiment> (1.1. Configuration example) First, with reference to FIGS. 1 and 2, a configuration example of a photodetector according to an embodiment of the present disclosure will be described. FIG. 1 is a longitudinal sectional view showing an example of a cross-sectional configuration of a photodetector 1 according to the present embodiment. FIG. 2 is a plan view showing an example of a plan configuration of the photodetector 1 according to the present embodiment.

[0013] First, with reference to FIG. 1, the cross-sectional configuration of the photodetector 1 according to the present embodiment will be described. The cross-sectional configuration of the photodetector 1 shown in FIG. 1 corresponds to the cross-sectional configuration at the A-AA cutting line of the plan configuration of the photodetector 1 shown in FIG. 2.

[0014] As shown in FIG. 1, the photodetector 1 includes, for example, a semiconductor layer 100 including a SPAD (Single Photon Avalanche Diode), a multilayer wiring layer 150, a pixel defining film 111, and an on-chip lens 101. In this specification, the side on which the multilayer wiring layer 150 is provided is also referred to as the front side, and the side on which the on-chip lens 101 is provided is also referred to as the back side.

[0015] The semiconductor layer 100 is made of, for example, a semiconductor such as Si (silicon). The semiconductor layer 100 includes, for example, a well layer 120, a P++ type region 121, an N++ type region 123, a P type region 125, a separation region 110, and a hole accumulation region 113. The well layer 120, the P++ type region 121, and the N++ type region 123 constitute a so-called SPAD.

[0016] The well layer 120 is, for example, a semiconductor region having a conductivity type of P type or N type. Specifically, the well layer 120 may be a P type or N type semiconductor region having an impurity concentration lower than that of the P++ type region 121 and the N++ type region 123. By providing the well layer 120 as a low-concentration P type or N type semiconductor region, it is more easily depleted, so that the photon detection efficiency (PDE) of the SPAD can be further increased.

[0017] The P++ type region 121 is, for example, a semiconductor region having a conductivity type of P type and a high impurity concentration. The P++ type region 121 is provided inside the well layer 120 closer to the well layer 120 than the N++ type region 123 and forms a PN junction at the interface with the N++ type region 123. In addition, the P++ type region 121 includes a multiplication region that multiplies carriers generated by light incident on the well layer 120 through the on-chip lens 101 by avalanche multiplication. The P++ type region 121 can further increase the PDE of the SPAD by being depleted.

[0018] The N++ type region 123 is, for example, a semiconductor region having an N-type conductivity type and a high impurity concentration. The N++ type region 123 is provided on the surface side of the well layer 120 with respect to the P++ type region 121. Further, the N++ type region 123 protrudes on the surface side of the well layer 120 and has a convex portion continuously provided over the entire circumference at the outer edge end. The N++ type region 123 is electrically connected to the contact 145 provided in the multilayer wiring layer 150 at the convex portion. Thereby, the N++ type region 123 can function as the cathode of the SPAD.

[0019] The P-type region 125 is provided at the center of the N++ type region 123 and on the surface side of the well layer 120 further than the N++ type region 123. The P-type region 125 is a P-type semiconductor region and is provided so as to have a potential different from that of the anode described later. Specifically, the P-type region 125 may be provided to have the same potential as the ground (GND) or the cathode. According to this, the P-type region 125 can function as a region where holes (that is, positive holes) are accumulated. By accumulating holes, the P-type region 125 can reduce the inflow of dark current generated on the surface of the well layer 120 and the damage during the formation of the N++ type region 123. Therefore, since the P-type region 125 can reduce the generation rate of dark electrons, the background noise of the SAPD can be further suppressed.

[0020] The isolation region 110 is provided to penetrate the well layer 120 and separates the well layer 120 for each pixel. Specifically, the isolation region 110 is provided in a grid-like planar shape to separate the well layer 120 into a plurality of pixel regions arranged in a matrix on the plane. Note that the isolation region 110 may be provided so as to penetrate the well layer 120 from the surface to the back surface as shown in FIG. 1, or may be provided so as to penetrate a part of the well layer 120 from the surface to the middle.

[0021] The isolation region 110 may be composed of a metal layer 110A and an insulating layer 110B provided on the side surface of the metal layer 110A. The metal layer 110A is provided with, for example, W (tungsten). The metal layer 110A can reduce crosstalk between adjacent pixels by reflecting stray light incident from adjacent pixels. The insulating layer 110B is provided on the side surface of the metal layer 110A with an insulating material such as SiO2 (silicon dioxide). The insulating layer 110B is provided to electrically insulate the metal layer 110A and the well layer 120.

[0022] The hole accumulation region 113 is provided along the side surface of the isolation region 110. The hole accumulation region 113 is, for example, a semiconductor region with a P-type conductivity type and is provided as a region where holes are accumulated. The hole accumulation region 113 is provided at the interface where different materials are in contact, and by absorbing electrons generated at the interface, the generation of dark current can be suppressed. Further, since the hole accumulation region 113 is provided on the side surface of the isolation region 110, an electric field can be formed in the in-plane direction of the semiconductor layer 100, making it easier to collect carriers in the multiplication region of the P++ type region 121. According to this, the hole accumulation region 113 can increase the PDE of the SPAD.

[0023] Also, the hole accumulation region 113 is electrically connected to a contact 147 provided in the multilayer wiring layer 150 on the surface side of the well layer 120. Thereby, the hole accumulation region 113 on the surface side of the well layer 120 can function as the anode of the SPAD.

[0024] The multilayer wiring layer 150 includes wirings that are electrically connected to the cathode and anode of the SPAD provided in the semiconductor layer 100 and is laminated on the surface side of the semiconductor layer 100. The multilayer wiring layer 150 includes, for example, a gate electrode 131, a P-type region electrode 133, contacts 141, 143, 145, 147, a wiring layer 151, an interlayer insulating layer 153, and a junction 155.

[0025] The gate electrode 131 is provided via a gate insulating film (not shown) on the well layer 120 in the region between the hole accumulation region 113 and the N++ type region 123. For example, the gate electrode 131 may be provided on the gate insulating film with a metal such as W (tungsten), Cu (copper), or Al (aluminum), or polysilicon. The gate insulating film not shown may be provided on the well layer 120 with SiO2 (silicon dioxide).

[0026] Here, with reference to FIG. 2, the planar arrangement of the gate electrode 131 will be described more specifically.

[0027] As shown in FIG. 2, in the photodetector 1, the separation region 110 is provided in a lattice shape, and the pixel regions 200 are provided in rectangular regions separated in a matrix in the separation region 110. The pixel region 200 includes a hole accumulation region 113, a gate electrode 131, a P++ type region 121, and an N++ type region 123, respectively, and constitutes one pixel in the pixel array of the photodetector 1.

[0028] The hole accumulation region 113 is provided along the inside of the separation region 110. The P++ type region 121 is provided at the center of the pixel region 200 in a rectangular shape. The N++ type region 123 is provided at the center of the pixel region 200 in a rectangular shape so as to include the region where the P++ type region 121 is provided. The region where the N++ type region 123 is provided is a region related to the amplification of carriers by avalanche multiplication in the pixel region 200, and is also referred to as an amplification region 210.

[0029] The gate electrode 131 is provided in the region between the hole accumulation region 113 and the amplification region 210. Specifically, the gate electrode 131 is provided in an annular shape so as to surround the periphery of the amplification region 210 (that is, the N++ type region 123) provided in a rectangular shape.

[0030] Since the gate electrode 131 has light reflectivity, it can reflect the light that enters the multilayer wiring layer 150 from between the hole accumulation region 113 and the N++ type region 123. According to this, the gate electrode 131 can pass through the well layer 120 without contributing to carrier generation, reflect the light that tries to enter the multilayer wiring layer 150, and return it to the well layer 120 side. Therefore, the amount of charge generated in the P++ type region 121 and the N++ type region 123 can be increased. Thus, the gate electrode 131 can improve the PDE (Photon Detection Efficiency) of the SPAD.

[0031] In addition, in order to reflect more light passing through the well layer 120, the gate electrode 131 is preferably provided to spread over the entire region between the hole accumulation region 113 and the amplification region 210.

[0032] Also, the gate electrode 131 is provided so that a negative bias voltage is applied through the contact 141. When a negative bias voltage is applied to the gate electrode 131, a potential gradient can be formed in the well layer 120 under the gate electrode 131. According to this, the gate electrode 131 can discharge carriers to the outside of the well layer 120 by attracting the carriers to the gate electrode 131 side by the potential gradient. Therefore, the gate electrode 131 can prevent the carriers generated in the well layer 120 from remaining inside the well layer 120 and becoming a noise source.

[0033] The P-type region electrode 133 is provided on the P-type region 125. Specifically, the P-type region electrode 133 is provided on the well layer 120 inside the region surrounded by the convex portion of the N++ type region 123 so as not to contact the convex portion of the N++ type region 123. The P-type region electrode 133 applies the same potential as the ground (GND) or the cathode potential to the P-type region 125.

[0034] Contacts 141, 143, 145, and 147 electrically connect each of the electrodes provided on the well layer 120, as well as each of the cathode and anode provided in the well layer 120, to the wiring layer 151. Specifically, contact 141 electrically connects the gate electrode 131 to the wiring layer 151, and contact 143 electrically connects the P-type region electrode 133 to the wiring layer 151. Contact 145 electrically connects the N++ type region 123 that functions as the cathode of the SPAD to the wiring layer 151, and contact 147 electrically connects the surface side of the hole accumulation region 113 that functions as the anode of the SPAD to the wiring layer 151. Contacts 141, 143, 145, and 147 may be provided as a single-layer structure or a stacked structure of a metal such as Ti (titanium), Ta (tantalum), or W (tungsten), or a compound of these metals.

[0035] The wiring layer 151 is provided inside the multilayer wiring layer 150 with a metal material such as Cu (copper) or Al (aluminum). Specifically, the wiring layer 151 is provided in a plurality of layers sandwiching the interlayer insulating layer 153, and is electrically connected to each other by contacts passing through the interlayer insulating layer 153. The wiring layer 151 electrically connects each of the electrodes provided on the well layer 120, as well as each of the cathode and anode provided in the well layer 120, to a predetermined circuit.

[0036] The interlayer insulating layer 153 is provided so as to embed the wiring layer 151 with an insulating material such as SiO2 (silicon dioxide) or SiN (silicon nitride). The interlayer insulating layer 153 forms the layer structure of the multilayer wiring layer 150 and electrically insulates the wiring layers 151 provided inside the multilayer wiring layer 150 from each other.

[0037] The joint portion 155 is provided, for example, when forming the photodetector 1 by bonding substrates together, to form an electrical connection point between the substrates. Specifically, the joint portion 155 is provided by bringing into contact electrodes provided so as to be exposed on the surface of the substrate with each other and then bonding the electrodes by heat treatment or the like. By using the joint portion 155, the photodetector 1 can be formed, for example, by bonding a semiconductor substrate provided with an SPAD and a semiconductor substrate provided with a signal processing circuit. According to this, the manufacturing process difficulty of the photodetector 1 can be reduced. Note that depending on the manufacturing process of the photodetector 1, the joint portion 155 may not be provided.

[0038] The pixel definition film 111 is provided on the surface (i.e., the back side) opposite to the side where the multilayer wiring layer 150 of the separation region 110 is laminated. The pixel definition film 111, also referred to as a black matrix, is provided around the pixel to prevent light from entering the separation region 110 between the pixels. The pixel definition film 111 may be provided, for example, with W (tungsten) or the like.

[0039] Note that the pixel definition film 111 illustrated between the well layer 120 and the on-chip lens 101 in FIG. 1 is the pixel definition film 111 provided on the back side of the separation region 110 on the front side or the back side facing the paper surface of the well layer 120. Actually, no pixel definition film 111 is provided between the well layer 120 and the on-chip lens 101 inside the pixel region surrounded by the separation region 110.

[0040] The on-chip lens 101 is provided, for example, for each pixel on the back side of the semiconductor layer 100. The on-chip lens 101 is provided with a transparent optical material and condenses the light incident on the well layer 120.

[0041] According to the photodetector 1 having the above configuration, the light passing through the well layer 120 without contributing to the generation of carriers can be reflected toward the well layer 120 side by the gate electrode 131. Therefore, the photodetector 1 can improve the amount of carrier generation in the well layer 120 and improve the PDE of the SPAD. Thus, the photodetector 1 can further improve the light detection sensitivity.

[0042] (1.2. Operating example) Subsequently, with reference to FIGS. 3 and 4, an operating example of the photodetector 1 according to the present embodiment will be described. FIG. 3 is a graph schematically showing the transition of the SPAD output of the photodetector 1 according to the present embodiment and the voltage applied to the gate electrode 131. FIG. 4 is a longitudinal sectional view schematically showing the potential gradient generated from the gate electrode 131 to which a negative bias voltage is applied.

[0043] In the SPAD included in the photodetector 1 according to the present embodiment, a voltage higher than the breakdown voltage is applied between the anode (the surface side of the hole accumulation region 113) and the cathode (the N++ type region 123). As a result, in the SPAD, a strong electric field is applied to the multiplication regions of the N++ type region 123 and the P++ type region 121, and the carriers generated by the photoelectric conversion of the incident light are avalanche multiplied in the multiplication region. Thus, the photodetector 1 can obtain an amplified light detection signal.

[0044] The avalanche multiplication can be stopped by controlling the voltage between the anode and the cathode to be lower than the breakdown voltage via a resistor or the like. For example, the photodetector 1 can generate a voltage drop and lower the cathode potential below the breakdown voltage by flowing the current generated by avalanche multiplying the carriers from the cathode to the resistor. Thereby, the photodetector 1 can stop the avalanche multiplication after the light is incident. Such an operation of the photodetector 1 is also referred to as a quench operation. Thereafter, the photodetector 1 resets the voltage between the anode and the cathode to a voltage higher than the breakdown voltage so that new light can be detected.

[0045] Here, in the photodetector 1, noise peculiar to the SPAD called afterpulse may occur. The afterpulse is a phenomenon in which, after detecting a signal based on the light incident on the photodetector 1, a signal is detected again even though no new light is incident. As a cause of the afterpulse, for example, it is considered that a large number of carriers generated by avalanche multiplication continue to remain in the well layer 120 or the like even after the quenching operation. The remaining carriers generate avalanche multiplication when a voltage higher than the breakdown voltage is applied between the anode and the cathode in order to detect new light, and thus the current due to the avalanche multiplication is considered to be detected as an afterpulse.

[0046] In the photodetector 1 according to the present embodiment, as shown in FIG. 3, when a quenching operation occurs in the SPAD and the voltage decreases, a negative bias voltage is applied to the gate electrode 131. The application of the negative bias voltage to the gate electrode 131 is performed, for example, until the current due to avalanche multiplication decreases, the voltage drop due to the resistor is eliminated, and the cathode potential returns to the potential at the level before light detection.

[0047] As shown in FIG. 4, due to the application of the negative bias voltage, a potential gradient BP caused by the negative bias voltage applied to the gate electrode 131 is generated in the well layer 120 under the gate electrode 131. Since the gate electrode 131 can attract the carriers remaining in the well layer 120 to the gate electrode 131 side by the potential gradient BP, the attracted carriers can be discharged to the outside of the well layer 120. According to this, the photodetector 1 can apply a voltage between the anode and the cathode in order to detect new light in a state where no carriers remain in the well layer 120, and thus the generation of after noise can be suppressed. That is, the photodetector 1 can suppress the generation of noise by applying a negative bias voltage to the gate electrode 131 provided in the region between the hole accumulation region 113 and the N++ type region 123 after the quenching operation.

[0048] (1.3. Modification example) (First modification example) Next, with reference to FIG. 5, a configuration example of the photodetector according to the first modification will be described. FIG. 5 is a longitudinal sectional view showing an example of the sectional configuration of the photodetector 11 according to the first modification.

[0049] As shown in FIG. 5, the photodetector 11 according to the first modification has a different three-dimensional shape of the gate electrode 131 from that of the photodetector 1 shown in FIGS. 1 and 2. Regarding other configurations, since the photodetector 11 according to the first modification is the same as the photodetector 1 shown in FIGS. 1 and 2, the description here is omitted.

[0050] In the photodetector 11 according to the first modification, the gate electrode 131 is provided to include a flat portion 131A and an embedded portion 131B. The gate electrode 131 may be provided with a metal such as W (tungsten), Cu (copper), or Al (aluminum), or polysilicon. Note that a gate insulating film (not shown) is provided between the flat portion 131A and the embedded portion 131B of the gate electrode 131 and the well layer 120.

[0051] The flat portion 131A is provided on the surface of the well layer 120 between the hole accumulation region 113 and the N++ type region 123. The flat portion 131A is provided to reflect light that passes through the well layer 120 and enters the multilayer wiring layer 150. Therefore, the flat portion 131A may be provided to extend over the entire region between the hole accumulation region 113 and the N++ type region 123.

[0052] The embedded portion 131B extends in the depth direction of the well layer 120 and is provided so as to be embedded inside the well layer 120. The embedded portion 131B is provided to spread the potential gradient formed when a negative bias voltage is applied to the gate electrode 131 to a deeper region of the well layer 120. According to this, the embedded portion 131B can discharge carriers remaining in a deeper portion of the well layer 120.

[0053] Therefore, in the photodetector 11 according to the first modification example, since the gate electrode 131 is provided to include the flat portion 131A and the embedded portion 131B, the remaining carriers that cause after-noise can be discharged more effectively. Thus, the photodetector 11 according to the first modification example can further suppress the generation of noise.

[0054] (Second Modification Example) Subsequently, with reference to FIG. 6, a configuration example of the photodetector according to the second modification example will be described. FIG. 6 is a plan view showing an example of the planar configuration of the photodetector 12 according to the second modification example.

[0055] As shown in FIG. 6, in the photodetector 12 according to the second modification example, the planar arrangement of the gate electrode 131 is different from that of the photodetector 1 shown in FIGS. 1 and 2. Regarding other configurations, since the photodetector 12 according to the second modification example is the same as the photodetector 1 shown in FIGS. 1 and 2, the description here is omitted.

[0056] In the photodetector 12 according to the second modification example, the gate electrode 131 is provided separately from each other in the region between each side of the amplification region 210 (that is, the N++ type region 123) provided in a rectangular shape and the hole accumulation region 113. For example, the gate electrodes 131 may be provided on the upper, lower, left, and right sides of the amplification region 210 in a rectangular shape separated from each other.

[0057] According to this, in the photodetector 12 according to the second modification example, by providing the gate electrode 131 in the above region, the controllability of the potential gradient formed when a negative bias voltage is applied to the gate electrode 131 can be improved. Therefore, the photodetector 12 according to the second modification example can control the ability to suppress the generation of noise. In addition, the photodetector 12 according to the second modification example can change the region where the gate electrode 131 is provided more flexibly.

[0058] (Third Modification Example) Next, with reference to FIG. 7, a configuration example of a photodetector according to a third modification will be described. FIG. 7 is a plan view showing an example of the planar configuration of the photodetector 13 according to the third modification.

[0059] As shown in FIG. 7, the photodetector 13 according to the third modification has a different planar arrangement of the gate electrodes 131 from the photodetector 1 shown in FIGS. 1 and 2. Regarding other configurations, since the photodetector 13 according to the third modification is the same as the photodetector 1 shown in FIGS. 1 and 2, the description here is omitted.

[0060] In the photodetector 13 according to the third modification, the gate electrodes 131 are provided so as to be separated from each other in the regions between the respective vertex portions of the amplification region 210 (i.e., the N++ type region 123) provided in a rectangular shape and the hole accumulation region 113. For example, the gate electrodes 131 may be provided in a rectangular shape separated from each other at the upper right, upper left, lower right, and lower left of the amplification region 210, respectively.

[0061] According to this, the photodetector 13 according to the third modification can improve the controllability of the potential gradient formed when a negative bias voltage is applied to the gate electrode 131 by providing the gate electrode 131 in the above region. Therefore, the photodetector 13 according to the third modification can control the ability to suppress the generation of noise. In addition, the photodetector 13 according to the third modification can more flexibly change the region where the gate electrode 131 is provided.

[0062] (Fourth Modification) Subsequently, with reference to FIGS. 8 and 9, a configuration example of a photodetector according to a fourth modification will be described. FIG. 8 is a plan view showing an example of the planar configuration of the photodetector 14 according to the fourth modification, and FIG. 9 is a longitudinal sectional view showing an example of the sectional configuration of the photodetector 14 according to the fourth modification. The sectional configuration of the photodetector 14 shown in FIG. 9 corresponds to the sectional configuration at the B - BB cutting line of the planar configuration of the photodetector 14 shown in FIG. 8.

[0063] As shown in FIGS. 8 and 9, the photodetector 14 according to the fourth modification has a different planar arrangement of the gate electrode 131 from that of the photodetector 1 shown in FIGS. 1 and 2. Regarding other configurations, since the photodetector 14 according to the fourth modification is the same as the photodetector 1 shown in FIGS. 1 and 2, the description here is omitted.

[0064] In the photodetector 14 according to the fourth modification, the gate electrode 131 is provided in regions between each of the side portions of the amplification region 210 (i.e., the N++ type region 123) provided in a rectangular shape and each of the side portions of the amplification region 210 of the adjacent pixel region 200, being spaced apart from each other. That is, the gate electrode 131 is provided continuously with the gate electrode 131 of the adjacent pixel region 200 across the separation region 110. For example, the gate electrode 131 may be provided in each of the four directions of up, down, left, and right of the amplification region 210 in a rectangular shape that extends across the separation region 110 and spreads to the adjacent pixel region 200.

[0065] As shown in FIG. 9, since the gate electrode 131 extends not only on the well layer 120 but also on the hole accumulation region 113 and the separation region 110, the gate electrode 131 is provided also on the metal layer 110A of the separation region 110. In such a case, a gate insulating film (not shown) provided on the separation region 110 may be provided with a film thickness thicker than that of the gate insulating film (not shown) provided on the well layer 120 and the hole accumulation region 113 in order to ensure the insulation between the gate electrode 131 and the metal layer 110A.

[0066] According to this, the photodetector 14 according to the fourth modification can improve the controllability of the potential gradient formed when a negative bias voltage is applied to the gate electrode 131 by providing the gate electrode 131 in the above regions. Therefore, the photodetector 14 according to the fourth modification can control the ability to suppress the generation of noise. Further, since the gate electrode 131 is continuously provided in the adjacent pixel region 200 in the photodetector 14 according to the fourth modification, the number of contacts 141 for controlling the potential of the gate electrode 131 can be reduced.

[0067] <2. Application Examples> (Application Example to Depth Sensor) The photodetector 1 according to an embodiment of the present disclosure can be applied to, for example, a device for measuring distance.

[0068] For example, a ToF (Time of Flight) type sensor is a sensor that measures the distance to an object by measuring the time until the light emitted by itself is reflected by the object and returns.

[0069] Specifically, in a ToF type sensor, first, based on a supplied trigger pulse, light (light transmission pulse) is emitted from a light pulse transmitter. The emitted light transmission pulse is reflected by the object, and the reflected light (light reception pulse) is received by a light pulse receiver. At this time, the difference between the time when the light transmission pulse is emitted and the time when the light reception pulse is received corresponds to the time according to the distance to the object, that is, the time of flight of light (TOF). Thereby, the ToF type sensor can derive the distance to the object by deriving the time of flight of light. The photodetector 1 according to the present embodiment can be used, for example, as a light pulse receiver.

[0070] Specifically, in a ToF type sensor, the trigger pulse is supplied to the light pulse transmitter and also to a flip - flop circuit. The light pulse transmitter emits a short - time light pulse to the object when the trigger pulse is supplied. Also, the flip - flop circuit is reset when the trigger pulse is supplied. The light pulse receiver that has received the reflected light of the emitted light pulse generates an electrical pulse based on the received reflected light. The generated electrical pulse is supplied to the flip - flop circuit to reset the flip - flop circuit. Thereby, the flip - flop circuit generates a gate signal having a pulse width corresponding to the time of flight TOF. Therefore, the ToF type sensor can calculate the time of flight TOF by counting the generated gate signal using a clock signal or the like, and generate distance information to the object.

[0071] (Application examples to mobile bodies) The technology according to the present disclosure (this technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of mobile body such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility device, an airplane, a drone, a ship, a robot, etc.

[0072] FIG. 10 is a block diagram showing a schematic configuration example of a vehicle control system which is an example of a mobile body control system to which the technology according to the present disclosure can be applied.

[0073] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in FIG. 10, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an out-vehicle information detection unit 12030, an in-vehicle information detection unit 12040, and an integrated control unit 12050. Further, as a functional configuration 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.

[0074] The drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 functions as a control device such as a driving force generation device for generating a driving force of the vehicle such as an internal combustion engine or a driving motor, a driving force transmission mechanism for transmitting the driving 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.

[0075] The body system control unit 12020 controls the operations of various devices equipped on the vehicle 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 a headlamp, a backlamp, a brake lamp, a turn signal, or a fog lamp. In this case, radio waves transmitted from a portable device that substitutes for a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these inputs of radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0076] The vehicle exterior 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 vehicle exterior information detection unit 12030. The vehicle exterior information detection unit 12030 causes the imaging unit 12031 to capture an image of the outside of the vehicle and receives the captured image. The vehicle exterior information detection unit 12030 may perform object detection processing or distance detection processing on objects such as people, vehicles, obstacles, signs, or characters on the road surface based on the received image.

[0077] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal according to the amount of received light. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. Also, the light received by the imaging unit 12031 may be visible light or non-visible light such as infrared light.

[0078] The vehicle interior 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 vehicle interior information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that images the driver, and the vehicle interior information detection unit 12040 may calculate the degree of driver fatigue or concentration based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0079] Based on the information inside and outside the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, the microcomputer 12051 can calculate the control target values of the driving force generation device, the steering mechanism, or the braking device, and output a control command to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control for realizing functions of ADAS (Advanced Driver Assistance System) including collision avoidance or shock mitigation of the vehicle, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, collision warning of the vehicle, or lane departure warning of the vehicle.

[0080] In addition, based on the information around the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, etc., which runs autonomously without relying on the driver's operation, by controlling the driving force generation device, the steering mechanism, or the braking device, etc.

[0081] Also, based on the exterior information of the vehicle acquired by the vehicle exterior information detection unit 12030, the microcomputer 12051 can output a control command to the body system control unit 12020. For example, the microcomputer 12051 can perform cooperative control for the purpose of anti-glare, such as controlling the headlamp according to the position of the preceding vehicle or oncoming vehicle detected by the vehicle exterior information detection unit 12030 and switching the high beam to the low beam.

[0082] The audio-visual output unit 12052 transmits at least one of the audio and video output signals to an output device capable of notifying information visually or auditorily to the vehicle occupants or outside the vehicle. In the example of FIG. 10, the output devices are exemplified by the audio speaker 12061, the display unit 12062, and the instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0083] FIG. 11 is a diagram showing an example of the installation position of the imaging unit 12031.

[0084] In FIG. 11, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0085] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided at positions such as the front nose, side mirror, rear bumper, back door of the vehicle 12100, and the upper part of the front glass in the vehicle interior, for example. The imaging unit 12101 provided at the front nose and the imaging unit 12105 provided at the upper part of the front glass in the vehicle interior mainly acquire images in front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images on the side of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or the back door mainly acquires images behind the vehicle 12100. The imaging unit 12105 provided at the upper part of the front glass in the vehicle interior is mainly used for detecting a preceding vehicle or detecting pedestrians, obstacles, traffic lights, traffic signs, or lanes.

[0086] Note that FIG. 11 shows an example of the imaging ranges of the imaging units 12101 to 12104. The imaging range 12111 indicates the imaging range of the imaging unit 12101 provided at the front nose, and the imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively. The imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or the back door. For example, by overlapping the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0087] 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 including a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0088] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 determines the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the temporal change in this distance (relative speed with respect to the vehicle 12100). By doing so, it can extract, as the leading vehicle, the closest three-dimensional object on the traveling path of the vehicle 12100 that is traveling in substantially the same direction as the vehicle 12100 at a predetermined speed (for example, 0 km / h or more). Further, the microcomputer 12051 can set the inter-vehicle distance to be secured in advance in front of the leading vehicle and perform automatic brake control (including follow-up stop control) and automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, etc., without relying on the driver's operation.

[0089] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into motorcycles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects, and can use it for automatic avoidance of obstacles. For example, the microcomputer 12051 discriminates between obstacles around the vehicle 12100 that are visible to the driver of the vehicle 12100 and those that are difficult to visually recognize. Then, the microcomputer 12051 determines the collision risk indicating the degree of danger of collision with each obstacle, and when the collision risk is equal to or greater than the set value and there is a possibility of collision, it outputs an alarm to the driver via the audio speaker 12061 or the display unit 12062, or performs forced deceleration or avoidance steering via the drive system control unit 12010, thereby providing driving support for collision avoidance.

[0090] 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 a pedestrian exists in the captured images of the imaging units 12101 to 12104. Such recognition of 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 indicating the outline of an object to determine whether it is a pedestrian. When the microcomputer 12051 determines that a pedestrian exists in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio-visual image output unit 12052 controls the display unit 12062 to superimpose and display a rectangular outline for emphasizing the recognized pedestrian. Further, the audio-visual image output unit 12052 may control the display unit 12062 to display an icon or the like indicating a pedestrian at a desired position.

[0091] As described above, an example of a vehicle control system to which the technology according to the present disclosure can be applied has been described. The technology according to the present disclosure can be applied to, among the configurations described above, the imaging unit 12031 and the like. Since the light detector 1 according to the present embodiment can output ranging information with less noise, the accuracy of vehicle control can be improved by applying it to the above configuration.

[0092] (Application Example to Endoscopic Surgery System) The technology according to the present disclosure (this technology) may be applied to, for example, an endoscopic surgery system.

[0093] FIG. 12 is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (this technology) can be applied.

[0094] In FIG. 12, it shows a state where an operator (doctor) 11131 is performing an operation on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 includes an endoscope 11100, other surgical instruments 11110 such as a pneumoperitoneum tube 11111 and an energy treatment instrument 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 equipped with various devices for endoscopic surgery.

[0095] The endoscope 11100 is composed of a lens barrel 11101 whose region of a predetermined length from the tip is inserted into the body cavity of the patient 11132, and a camera head 11102 connected to the proximal end of the lens barrel 11101. In the illustrated example, an endoscope 11100 configured as a so-called rigid endoscope having a rigid lens barrel 11101 is shown, but the endoscope 11100 may be configured as a so-called flexible endoscope having a flexible lens barrel.

[0096] An opening in which an objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and the light generated by the light source device 11203 is guided to the tip of the lens barrel through a light guide extending inside the lens barrel 11101 and irradiated toward the observation target in the body cavity of the patient 11132 through the objective lens. Note that the endoscope 11100 may be a direct vision endoscope, a forward oblique endoscope, or a side vision endoscope.

[0097] An optical system and an imaging element are provided inside the camera head 11102, and the reflected light (observation light) from the observation target is condensed on the imaging element by the optical system. The observation light is photoelectrically converted by the imaging element, and an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image, is generated. The image signal is transmitted as RAW data to a camera control unit (CCU) 11201.

[0098] The CCU 11201 is composed of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 11100 and the display device 11202. Further, the CCU 11201 receives an image signal from the camera head 11102, and performs various image processes on the image signal for displaying an image based on the image signal, such as development processing (demosaicing processing).

[0099] The display device 11202 displays an image based on the image signal that has been subjected to image processing by the CCU 11201 under the control of the CCU 11201.

[0100] The light source device 11203 is composed of a light source such as an LED (light emitting diode), and supplies irradiation light for photographing the surgical site or the like to the endoscope 11100.

[0101] The input device 11204 is an input interface for the endoscope surgical system 11000. The user can input various information and instruction inputs to the endoscope surgical system 11000 via the input device 11204. For example, the user inputs an instruction to change imaging conditions (type of irradiation light, magnification, focal length, etc.) by the endoscope 11100.

[0102] The treatment instrument control device 11205 controls the driving of the energy treatment instrument 11112 for tissue cauterization, incision, or blood vessel sealing. The pneumoperitoneum device 11206 sends gas into the body cavity of the patient 11132 via the pneumoperitoneum tube 11111 in order to expand the body cavity of the patient for the purpose of securing the visual field by the endoscope 11100 and securing the working space for the surgeon. The recorder 11207 is a device capable of recording various information related to the surgery. The printer 11208 is a device capable of printing various information related to the surgery in various forms such as text, image, or graph.

[0103] Note that the light source device 11203 that supplies irradiation light when photographing the surgical site with the endoscope 11100 can be configured from, for example, an LED, a laser light source, or a white light source composed of a combination thereof. When a white light source is configured by a combination of RGB laser light sources, since the output intensity and output timing of each color (each wavelength) can be controlled with high precision, the white balance of the captured image can be adjusted in the light source device 11203. Further, in this case, the laser light from each of the RGB laser light sources is irradiated to the observation target in a time-division manner, and by controlling the driving of the imaging element of the camera head 11102 in synchronization with the irradiation timing, it is also possible to capture images corresponding to each of RGB in a time-division manner. According to this method, a color image can be obtained without providing a color filter on the imaging element.

[0104] Further, the driving of the light source device 11203 may be controlled so as to change the intensity of the output light at predetermined time intervals. By controlling the driving of the imaging element of the camera head 11102 in synchronization with the timing of the change in the intensity of the light and acquiring images in a time-division manner and synthesizing the images, it is possible to generate a high-dynamic-range image without so-called black crush and white clip.

[0105] Further, the light source device 11203 may be configured to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, by utilizing the wavelength dependence of light absorption in body tissues, a narrow-band light is irradiated as compared with the irradiation light (i.e., white light) during normal observation, so-called narrow-band imaging is performed to capture a predetermined tissue such as blood vessels in the mucosal surface layer with high contrast. Alternatively, in special light observation, fluorescence observation may be performed to obtain an image by fluorescence generated by irradiating excitation light. In fluorescence observation, excitation light is irradiated to the body tissue to observe the fluorescence from the body tissue (autofluorescence observation), or a reagent such as indocyanine green (ICG) is locally injected into the body tissue and excitation light corresponding to the fluorescence wavelength of the reagent is irradiated to the body tissue to obtain a fluorescence image. The light source device 11203 can be configured to supply such narrow-band light and / or excitation light corresponding to special light observation.

[0106] FIG. 13 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG. 12.

[0107] The camera head 11102 includes a lens unit 11401, an imaging unit 11402, a driving unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 includes a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are communicably connected to each other by a transmission cable 11400.

[0108] The lens unit 11401 is an optical system provided at a connection portion with the lens barrel 11101. The observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is configured by combining a plurality of lenses including a zoom lens and a focus lens.

[0109] The imaging device that constitutes the imaging unit 11402 may be one (so-called single-plate type) or multiple (so-called multi-plate type). When the imaging unit 11402 is configured as a multi-plate type, for example, image signals corresponding to RGB respectively may be generated by each imaging device, and a color image may be obtained by synthesizing them. Alternatively, the imaging unit 11402 may be configured to have a pair of imaging devices for respectively acquiring image signals for the right eye and the left eye corresponding to 3D (dimensional) display. By performing 3D display, the surgeon 11131 can more accurately grasp the depth of the biological tissue in the surgical site. Note that when the imaging unit 11402 is configured as a multi-plate type, a plurality of lens units 11401 may be provided corresponding to each imaging device.

[0110] Also, the imaging unit 11402 does not necessarily have to be provided on the camera head 11102. For example, the imaging unit 11402 may be provided immediately behind the objective lens inside the lens barrel 11101.

[0111] The drive unit 11403 is constituted by an actuator, and under the control from the camera head control unit 11405, moves the zoom lens and the focus lens of the lens unit 11401 along the optical axis by a predetermined distance. Thereby, the magnification and focus of the captured image by the imaging unit 11402 can be appropriately adjusted.

[0112] The communication unit 11404 is constituted by a communication device for transmitting and receiving various information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 as RAW data to the CCU 11201 via the transmission cable 11400.

[0113] In addition, the communication unit 11404 receives a control signal for controlling the drive of the camera head 11102 from the CCU 11201 and supplies it to the camera head control unit 11405. The control signal includes information related to imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value at the time of imaging, and / or information specifying the magnification and focus of the captured image.

[0114] Note that the imaging conditions such as the above frame rate, exposure value, magnification, and focus may be appropriately specified by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. In the latter case, so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function are installed in the endoscope 11100.

[0115] The camera head control unit 11405 controls the drive of the camera head 11102 based on the control signal from the CCU 11201 received via the communication unit 11404.

[0116] The communication unit 11411 is composed of a communication device for transmitting and receiving various kinds of information to and from the camera head 11102. The communication unit 11411 receives the image signal transmitted from the camera head 11102 via the transmission cable 11400.

[0117] In addition, the communication unit 11411 transmits a control signal for controlling the drive of the camera head 11102 to the camera head 11102. The image signal and the control signal can be transmitted by wire communication, optical communication, or the like.

[0118] The image processing unit 11412 performs various image processes on the image signal, which is RAW data transmitted from the camera head 11102.

[0119] The control unit 11413 performs various controls related to imaging of the surgical site and other areas by the endoscope 11100, and display of the captured images obtained by imaging the surgical site and other areas. For example, the control unit 11413 generates a control signal for controlling the drive of the camera head 11102.

[0120] Also, the control unit 11413 causes the display device 11202 to display a captured image in which the surgical site and other areas are reflected, based on the image signal that has been subjected to image processing by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition techniques. For example, the control unit 11413 can recognize surgical instruments such as forceps, specific biological sites, bleeding, mist during use of the energy treatment instrument 11112, etc., by detecting the shape, color, etc. of the edges of the objects included in the captured image. When causing the display device 11202 to display the captured image, the control unit 11413 may use the recognition result to superimpose and display various surgical support information on the image of the surgical site. By superimposing and displaying the surgical support information and presenting it to the surgeon 11131, the burden on the surgeon 11131 can be reduced, and the surgeon 11131 can surely proceed with the surgery.

[0121] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable corresponding to electrical signal communication, an optical fiber corresponding to optical communication, or a composite cable of these.

[0122] Here, in the illustrated example, communication is performed wired using the transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

[0123] The above has described an example of an endoscopic surgical system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to, for example, the endoscope 11100 or the imaging unit 11402 of the camera head 11102 among the configurations described above. Since the photodetector 1 according to the present embodiment can output ranging information with less noise, by being applied to the above configuration, the operation accuracy of the surgical instrument 11110 or the energy treatment instrument 11112 by the surgeon 11131 can be improved.

[0124] Here, although an endoscopic surgical system has been described as an example, the technology according to the present disclosure may also be applied to, for example, a microscopic surgical system or the like.

[0125] The above has described the technology according to the present disclosure by way of embodiments and modification examples. However, the technology according to the present disclosure is not limited to the above-described embodiments and the like, and various modifications are possible.

[0126] Furthermore, not all of the configurations and operations described in each embodiment are essential as the configurations and operations of the present disclosure. For example, among the components in each embodiment, components not described in the independent claims indicating the most general concept of the present disclosure should be understood as optional components.

[0127] The terms used throughout this specification and the appended claims should be construed as "non-limiting" terms. For example, the terms "comprising" or "included" should be construed as not being limited to the manner described as being included. The term "having" should be construed as not being limited to the manner described as having.

[0128] The terms used in this specification include terms that are used merely for convenience of explanation and are not used for the purpose of limiting the configuration and operation. For example, terms such as "right", "left", "up", and "down" merely indicate directions on the drawing being referred to. Also, the terms "inside" and "outside" merely indicate the direction toward the center of the element of interest and the direction away from the center of the element of interest, respectively. The same applies to terms similar to these and terms of the same purport.

[0129] Note that the technology according to the present disclosure can also adopt the following configuration. According to the technology according to the present disclosure having the following configuration, incident light that passes through the semiconductor layer and enters the multilayer wiring layer can be reflected by the gate electrode and returned to the semiconductor layer side. Therefore, the photodetector according to an embodiment of the present disclosure can increase the amount of carriers generated in the semiconductor layer by the incident light, and thus can further improve the detection sensitivity of light. The effects exhibited by the technology according to the present disclosure are not necessarily limited to the effects described herein, and any of the effects described in the present disclosure may be applicable. (1) including a PN junction provided in the depth direction of the semiconductor layer, an amplification region electrically connected to the cathode, and a separation region that defines a pixel region including the amplification region, and a hole accumulation region provided along the side surface of the separation region and electrically connected to the anode, and a gate electrode provided in a region between the amplification region and the hole accumulation region and laminated on the semiconductor layer with a gate insulating film interposed therebetween A photodetector comprising: (2) The photodetector according to (1) above, wherein the amplification region and the pixel region are each rectangular in shape. (3) The photodetector according to (1) or (2) above, wherein the gate electrode is provided in a region surrounding the amplification region. (4) The photodetector according to (3) above, wherein the gate electrode is continuously provided in a region between the amplification region and the hole accumulation region. (5) The gate electrode is provided in each of a plurality of regions separated from each other, and the photodetector according to (2) above. (6) The gate electrode is provided in each region between each of the side portions of the rectangular shape of the amplification region and the hole accumulation region, and the photodetector according to (5) above. (7) The gate electrode is provided in each region between each of the vertex portions of the rectangular shape of the amplification region and the hole accumulation region, and the photodetector according to (5) above. (8) The gate electrode is provided continuously with the gate electrode provided in the adjacent pixel region beyond the separation region, and the photodetector according to any one of (5) to (7) above. (9) The film thickness of the gate insulating film provided in the separation region is thicker than the film thickness of the gate insulating film provided in the pixel region, and the photodetector according to (8) above. (10) The gate electrode is provided so as to be applied with a negative bias voltage, and the photodetector according to any one of (1) to (9) above. (11) The gate electrode is provided embedded inside the semiconductor layer, and the photodetector according to (10) above. (12) The conductivity type of the hole accumulation region is P-type, and the photodetector according to any one of (1) to (11) above. (13) The contact for electrically connecting the amplification region and the cathode is provided at an end of the amplification region, A P-type region is provided on the surface of the semiconductor layer at the central portion of the amplification region, and the photodetector according to any one of (1) to (12) above. (14) The PN junction is provided by joining an N++ type region on a P++ type region provided inside the semiconductor layer, and the photodetector according to any one of (1) to (13) above.

[0130] This application claims priority based on Japanese Patent Application No. 2019-233854, filed with the Japan Patent Office on December 25, 2019, and all contents of this application are incorporated herein by reference.

[0131] Those skilled in the art can conceive various modifications, combinations, sub-combinations, and changes according to design requirements and other factors, and it is understood that they are included within the scope of the appended claims and their equivalents.

Claims

1. Each including a PN junction provided in the depth direction of the semiconductor layer, first and second amplification regions each electrically connected to the cathode, and a separation region defining a first pixel region including the first amplification region and a second pixel region adjacent to the first pixel region and including the second amplification region, a first hole accumulation region provided along the side surface of the separation region between the separation region and the first amplification region and electrically connected to the anode, a second hole accumulation region provided along the side surface of the separation region between the separation region and the second amplification region and electrically connected to the anode, a plurality of first gate electrodes respectively provided in a plurality of regions spaced apart from each other among the regions surrounding the first amplification region between the first amplification region and the first hole accumulation region, and respectively stacked on the surface of the semiconductor layer via a first gate insulating film, a plurality of second gate electrodes respectively provided in a plurality of regions spaced apart from each other among the regions surrounding the second amplification region between the second amplification region and the second hole accumulation region, and respectively stacked on the surface of the semiconductor layer via a second gate insulating film and comprising, the first and second amplification regions, and the first and second pixel regions are each rectangular in shape, one of the plurality of first gate electrodes is provided continuously with one of the plurality of second gate electrodes across the separation region, a photodetector.

2. The plurality of first gate electrodes are respectively provided in regions between each of the rectangular sides of the first amplification region and the first hole accumulation region, The plurality of second gate electrodes are respectively provided in regions between each of the rectangular sides of the second amplification region and the second hole accumulation region, the photodetector according to Claim 1.

3. The film thicknesses of the first and second gate insulating films respectively provided in the separation region are thicker than the film thicknesses of the first and second gate insulating films respectively provided in the first and second pixel regions, the photodetector according to Claim 1.

4. The PN junction is laminated in the order of an N++ type region and a P++ type region from the surface side, the photodetector according to Claim 1.

5. The first and second pixel regions each include a well layer and the PN junction, The photodetector according to claim 4, wherein the first and second gate electrodes are provided to be applied with a negative bias voltage.

6. The photodetector according to claim 1, wherein the conductivity type of the hole accumulation region is P-type.

7. The contact that electrically connects the amplification region and the cathode is provided at an end of the amplification region. The photodetector according to claim 1, wherein a P-type region is provided on the surface of the semiconductor layer at the central portion of the amplification region.

Images