Solid-state imaging element, light detection element, and light detection system

Abstract

A solid-state imaging element according to one embodiment of the present disclosure comprises: a light absorption layer that includes silicon and has a light-receiving surface in which a recess is provided; a separation region that is provided to the light absorption layer, at the periphery of the recess; and a first medium that has a lower refractive index than the refractive index of silicon and is provided so as to fill the recess.

Description

Solid-state imaging device, photodetector, and photodetection system

[0001] The present disclosure relates to a solid-state imaging device, a photodetector, and a photodetection system.

[0002] A solid-state imaging device has been proposed that has a reflection suppressing portion formed on the light-receiving surface of a semiconductor layer, and that diffracts incident light that enters the semiconductor layer with the reflection suppressing portion (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2021-168316

[0004] It is desirable to improve the sensitivity of a solid-state imaging device.

[0005] It is desirable to provide a solid-state imaging device that can improve sensitivity.

[0006] A solid-state imaging element according to an embodiment of the present disclosure includes a light-absorbing layer containing silicon and having a light-receiving surface with a recess provided therein, a separation region provided in the light-absorbing layer around the recess, and a first medium having a refractive index lower than that of silicon and configured to fill the recess.A light-detecting element according to an embodiment of the present disclosure includes a light-absorbing layer containing silicon and having a light-receiving surface with a recess provided therein, a separation region provided in the light-absorbing layer around the recess, and a first medium having a refractive index different from that of silicon and configured to fill the recess.A light-detecting system according to an embodiment of the present disclosure includes a light source capable of irradiating light onto an object, and a light-detecting element that receives light from the object.The light-detecting element includes a light-absorbing layer containing silicon and having a light-receiving surface with a recess provided therein, a separation region provided in the light-absorbing layer around the recess, and a first medium having a refractive index different from that of silicon and configured to fill the recess.

[0007] FIG. 1 is a block diagram illustrating an example of a schematic configuration of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating an example of a pixel unit of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 3A is a diagram illustrating an example of a configuration of a pixel of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 3B is a diagram illustrating another example of a configuration of a pixel of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 4 is a diagram illustrating another example of a configuration of a pixel of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 5A is a diagram illustrating an example of a cross-sectional configuration of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 5B is a diagram illustrating another example of a cross-sectional configuration of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 5C is a diagram illustrating another example of a cross-sectional configuration of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 5D is a diagram illustrating another example of a cross-sectional configuration of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 5E is a diagram illustrating another example of a cross-sectional configuration of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 6 is a diagram illustrating an example of a configuration of a solid-state imaging element according to a comparative example of the present disclosure. FIG. 7 is a diagram illustrating an example of a configuration of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 8 is a diagram illustrating an example configuration of a solid-state imaging element according to an embodiment of the present disclosure. FIG. 9A is a diagram illustrating an example configuration of an imaging device according to an embodiment of the present disclosure. FIG. 9B is a diagram illustrating an example configuration of an imaging device according to an embodiment of the present disclosure. FIG. 10A is a diagram illustrating an example configuration of an imaging device according to an embodiment of the present disclosure. FIG. 10B is a diagram illustrating an example configuration of an imaging device according to an embodiment of the present disclosure. FIG. 11 is a block diagram illustrating an example of a schematic configuration of a light detection system according to an embodiment of the present disclosure. FIG. 12 is a diagram illustrating an example configuration of a solid-state imaging element according to a first modification of the present disclosure. FIG. 13 is a diagram illustrating an example configuration of a solid-state imaging element according to the first modification of the present disclosure. FIG. 14 is a diagram illustrating an example configuration of a solid-state imaging element according to a second modification of the present disclosure. FIG. 15A is a diagram illustrating an example configuration of a solid-state imaging element according to a third modification of the present disclosure. FIG. 15B is a diagram illustrating an example configuration of a solid-state imaging element according to a third modification of the present disclosure. FIG. 16 is a diagram illustrating an example configuration of a solid-state imaging element according to a fourth modification of the present disclosure. FIG. 17 is a diagram for explaining another configuration example of a solid-state imaging device according to the fourth modification of the present disclosure.FIG. 18 is a diagram for describing an example configuration of a solid-state imaging element according to Modification 5 of the present disclosure. FIG. 19 is a diagram for describing an example configuration of a solid-state imaging element according to Modification 5 of the present disclosure. FIG. 20 is a diagram for describing an example configuration of a solid-state imaging element according to Modification 6 of the present disclosure. FIG. 21 is a diagram for describing an example configuration of a solid-state imaging element according to Modification 7 of the present disclosure. FIG. 22 is a diagram for describing an example configuration of a solid-state imaging element according to Modification 8 of the present disclosure. FIG. 23 is a diagram for describing another example configuration of a solid-state imaging element according to Modification 8 of the present disclosure. FIG. 24 is a diagram for describing an example configuration of a solid-state imaging element according to Modification 9 of the present disclosure. FIG. 25 is a diagram for describing an example configuration of a solid-state imaging element according to Modification 9 of the present disclosure. FIG. 26 is a diagram for describing an example configuration of a solid-state imaging element according to Modification 10 of the present disclosure. FIG. 27 is a diagram for describing an example configuration of a solid-state imaging element according to Modification 10 of the present disclosure. FIG. 28 is a diagram for describing another example configuration of a solid-state imaging element according to Modification 10 of the present disclosure. Fig. 29 is a diagram for explaining another example configuration of a solid-state imaging element according to Modification 10 of the present disclosure. Fig. 30 is a diagram for explaining an example configuration of a solid-state imaging element according to Modification 11 of the present disclosure. Fig. 31 is a diagram for explaining another example configuration of a solid-state imaging element according to Modification 11 of the present disclosure. Fig. 32 is a diagram for explaining an example configuration of a solid-state imaging element according to Modification 12 of the present disclosure. Fig. 33 is a diagram for explaining an example configuration of a solid-state imaging element according to Modification 12 of the present disclosure. Fig. 34 is a block diagram showing an example of a schematic configuration of a vehicle control system. Fig. 35 is an explanatory diagram showing an example of installation positions of an outside vehicle information detection unit and an imaging unit.

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order: 1. Embodiment 2. Modification 3. Usage example 4. Application example

[0009] 1. Embodiment Fig. 1 is a block diagram showing an example of a schematic configuration of a solid-state imaging element according to an embodiment of the present disclosure. Fig. 2 is a diagram showing an example of a pixel section of the solid-state imaging element according to the embodiment. The solid-state imaging element 1 is, for example, an imaging element having a plurality of pixels P including light-receiving elements (photoelectric conversion elements), and is configured to receive incident light and generate a signal. The solid-state imaging element 1 is an element capable of detecting incident light, and can also be called a photodetector element.

[0010] The solid-state imaging device 1 can generate a signal by receiving light that has passed through an optical system (not shown) including an optical lens. The solid-state imaging device 1 is configured using a semiconductor substrate (e.g., a silicon substrate) on which light receiving elements of each pixel P are provided. The solid-state imaging device 1 can have a structure (a stacked structure) configured by stacking multiple semiconductor layers, for example.

[0011] 1 or 2, the solid-state imaging device 1 has a region (pixel section 100) in which a plurality of pixels P are provided. The solid-state imaging device 1 has, for example, the pixel section 100 in which a plurality of pixels P are two-dimensionally arranged in a matrix. The solid-state imaging device 1 can also be called a two-dimensional solid-state imaging device. The pixel section 100 is a pixel array in which a plurality of pixels P are arranged. The light-receiving elements of the pixels P are, for example, photodiodes (PDs) and are configured to be able to photoelectrically convert light.

[0012] The solid-state imaging device 1 captures incident light from a subject to be measured via an optical system including an optical lens. The solid-state imaging device 1 captures an image of the subject formed by the optical lens. The solid-state imaging device 1 can photoelectrically convert the received light (e.g., infrared light, visible light, etc.) to generate pixel signals.

[0013] The light receiving element of the pixel P of the solid-state imaging device 1 is, for example, an APD (Avalanche Photo Diode), which is configured to receive light and output a current. The light receiving element (light receiving unit) of each pixel P of the pixel unit 100 is configured to generate a signal in response to the reception of photons.

[0014] The light receiving element of each pixel P may be configured as a SPAD (single photon avalanche diode). The light receiving element receives light (e.g., infrared light, visible light, etc.) from a measurement target, generates charges through photoelectric conversion, and generates a photocurrent. The solid-state imaging device 1 may be configured as, for example, a distance measuring sensor, an image sensor, etc.

[0015] The pixel P may include a light-receiving element capable of generating electric charges through photoelectric conversion and a readout circuit capable of outputting a pixel signal based on the electric charges photoelectrically converted by the light-receiving element. The readout circuit may include, for example, a transfer transistor, a floating diffusion, an amplification transistor, a selection transistor, a reset transistor, etc. The readout circuit may be, for example, a 4Tr (transistor) type pixel, which may also be referred to as a 4Tr type active pixel sensor pixel.

[0016] The solid-state imaging device 1 (photodetector device) is an element capable of performing distance measurement, and is configured to be capable of performing distance measurement using a time-of-flight (TOF) method, for example. The solid-state imaging device 1 is used, for example, as a distance measurement sensor capable of measuring distance using the TOF method. The solid-state imaging device 1 can be used in various electronic devices, such as digital still cameras, video cameras, and mobile phones.

[0017] The solid-state imaging device 1 may be configured as a ranging sensor capable of performing distance measurement using an indirect time of flight (iToF) method (i.e., an iToF type ranging sensor).The solid-state imaging device 1 may also be configured as a ranging sensor capable of performing distance measurement using a direct time of flight (dToF) method (i.e., a dToF type ranging sensor).

[0018] 2, the incident direction of light from the object to be measured is defined as the Z-axis direction, the left-right direction on the paper surface perpendicular to the Z-axis direction is defined as the X-axis direction, and the up-down direction on the paper surface perpendicular to the Z-axis and X-axis directions is defined as the Y-axis direction. In the following figures, directions may be indicated based on the direction of the arrow in FIG. 2.

[0019] 1 , the solid-state imaging element 1 includes a pixel section 100 (pixel array), a pixel control section 111, a signal processing section 112, and a control section 113. The solid-state imaging element 1 is also provided with, for example, a plurality of control lines L1 and a plurality of signal lines L2. The control line L1 is a signal line capable of transmitting a signal for controlling the pixel P, and is connected to the pixel control section 111 and the pixel P of the pixel section 100.

[0020] 1 , a plurality of control lines L1 are wired in the pixel unit 100 for each pixel row made up of a plurality of pixels P arranged in the horizontal direction (row direction). The control lines L1 are configured to transmit control signals for reading out signals from the pixels P. The control lines L1 can also be referred to as drive lines (or pixel drive lines) that transmit signals for driving the pixels P.

[0021] The signal line L2 is a signal line capable of transmitting a signal from the pixel P, and is connected to the pixel P of the pixel unit 100 and the signal processing unit 112. In the pixel unit 100, for example, one or more signal lines L2 are wired for each pixel column formed by a plurality of pixels P aligned in the vertical direction (column direction).

[0022] The signal line L2 is electrically connected to the pixel P and configured to be able to transmit a signal output from the pixel P. In the solid-state imaging device 1, a plurality of signal lines L2 may be provided for one pixel column. For example, the solid-state imaging device 1 may have a plurality of signal lines L2 for each pixel column including a plurality of pixels P.

[0023] The pixel control unit 111 is configured to be able to control each pixel P of the pixel unit 100. The pixel control unit 111 is a control circuit and is configured by a plurality of circuits including, for example, a buffer, a shift register, an address decoder, etc. The pixel control unit 111 generates a signal for controlling the pixel P and outputs it to each pixel P of the pixel unit 100 via a control line L1. The pixel control unit 111 is controlled by the control unit 113 and controls the pixels P of the pixel unit 100.

[0024] The pixel control unit 111 generates signals for controlling the pixels P, such as signals for controlling a readout circuit of the pixels P, and supplies the signals to each pixel P via a control line L1. The pixel control unit 111 can control the reading out of pixel signals from each pixel P. The pixel control unit 111 can also be said to be a pixel driving unit (pixel driving circuit) configured to be able to drive each pixel P.

[0025] The control unit 113 is configured to be able to control each unit of the solid-state imaging device 1. The control unit 113 receives an externally provided clock, data instructing an operation mode, etc., and can also output data such as internal information of the solid-state imaging device 1. The control unit 113 is a control circuit, and has, for example, a timing generator configured to be able to generate various timing signals.

[0026] The control unit 113 controls the driving of the pixel control unit 111, the signal processing unit 112, etc. based on various timing signals (pulse signals, clock signals, etc.) generated by the timing generator. The control unit 113 may include circuits such as a PLL (Phase Locked Loop) and a DAC (Digital to Analog Converter).

[0027] The signal processing unit 112 is a signal processing circuit configured to be able to perform signal processing. The signal processing unit 112 is configured by circuits that perform various types of signal processing on signals output from each pixel P. For example, a signal output from each pixel P selected and scanned by the pixel control unit 111 is input to the signal processing unit 112 via a signal line L2.

[0028] The signal processing unit 112 is configured to include an arithmetic circuit, a memory circuit, etc., and can perform various types of signal processing such as AD (Analog-Digital) conversion processing, noise reduction processing, counting (accumulation) processing, etc. of the signals of the pixels P. The signal processing unit 112 is configured to, for example, acquire the signals of each pixel P, and generate and output a signal related to the distance to the measurement target.

[0029] The signal processing unit 112 performs various signal processing on the signal from each pixel to generate and output distance image data representing the distance to the measurement target. The signal processing unit 112 and the control unit 113 may be integrated. The signal processing unit 112 and the control unit 113 may include a processor and a memory.

[0030] The pixel unit 100, pixel control unit 111, signal processing unit 112, control unit 113, etc. described above may be provided on a single substrate or may be provided separately on multiple substrates. The pixel control unit 111, signal processing unit 112, control unit 113, etc. may be provided in a peripheral region of the pixel unit 100 as, for example, peripheral circuits. The solid-state imaging device 1 may have a stacked structure configured by stacking multiple substrates.

[0031] 3A is a diagram showing an example of the configuration of a pixel of a solid-state imaging device according to an embodiment. A pixel P of the solid-state imaging device 1 has a light receiving element 10 and a readout circuit 20. The readout circuit 20 is provided, for example, for each light receiving element 10 or for each set of multiple light receiving elements 10. The solid-state imaging device 1 may have a configuration in which multiple pixels P share one readout circuit 20.

[0032] The light receiving element 10 is configured to receive light and generate a signal. The light receiving element 10 is, for example, a single photon avalanche diode (SPAD) and has a multiplication region (multiplication section) capable of avalanche multiplication. The light receiving element 10 can convert incident photons into electric charges and output a signal S10, which is an electrical signal corresponding to the incident photons.

[0033] The solid-state imaging device 1 may be configured as a distance measurement sensor having a plurality of pixels P each including a SPAD and capable of performing distance measurement using the dToF method. Note that the light receiving element 10 of the pixel P may also be referred to as a photoelectric conversion element (photoelectric conversion unit) configured to be able to photoelectrically convert light.

[0034] The light receiving element 10 is electrically connected to, for example, a power supply line, an electrode, or the like that can supply a predetermined voltage. In the example shown in Fig. 3A, one electrode of the light receiving element 10, that is, a cathode, is electrically connected to a supply circuit 21. The other electrode of the light receiving element 10, that is, an anode, is connected to the reference potential line.

[0035] The anode of the light receiving element 10 is electrically connected to, for example, a wiring, an electrode, or the like to which a relatively low power supply voltage is supplied. In the example shown in Fig. 3A, a voltage VSP is applied to the anode of the light receiving element 10 from a power supply unit (voltage source) capable of supplying voltage via a potential line L12 serving as a power supply line. The voltage VSP is, for example, a negative voltage.

[0036] The readout circuit 20 is configured to be able to output a signal based on the current of the light receiving element 10. The readout circuit 20 is configured to include circuits for reading out a signal based on the photocurrent flowing through the light receiving element 10, such as a supply circuit 21 and an output circuit 25. Note that the configuration of the readout circuit 20 is not limited to the example shown in the figure and can be changed as appropriate.

[0037] The supply circuit 21 is configured to be able to supply current and voltage to the light receiving element 10. The supply circuit 21 (supply unit) is electrically connected to the potential line L11 and can supply current and voltage to the light receiving element 10. The supply circuit 21 is configured, for example, by a current source that can supply current to the light receiving element 10. The potential line L11 is a wiring to which a predetermined potential (voltage) is applied. In the example shown in FIG. 3A , the potential line L11 is a power supply line to which a power supply voltage VDD is applied.

[0038] 3A, the supply circuit 21 is configured with a transistor M1. In the example shown in FIG. 3A, the transistor M1 is a P-type transistor (e.g., a PMOS transistor). One of the source and drain of the transistor M1, which serves as a current source, is electrically connected to a potential line L11 to which a power supply voltage VDD is applied, and the other of the source and drain of the transistor M1 is electrically connected to the light receiving element 10.

[0039] The transistor M1 of the supply circuit 21 generates a current corresponding to the signal level of a signal input to its gate, and can supply the generated current to the light receiving element 10. The supply circuit 21 (supply unit) may be configured using a resistive element. The supply circuit 21 may also be configured by a switch that electrically connects or disconnects the potential line L11 and the light receiving element 10.

[0040] A voltage can be applied between the cathode and anode of the light receiving element 10, which is the voltage supplied via the supply circuit 21 and the voltage VSP supplied by the potential line L12, resulting in a potential difference greater than the breakdown voltage of the light receiving element 10. In other words, the potential difference across the light receiving element 10 can be set to a potential difference greater than the breakdown voltage.

[0041] When a reverse bias voltage greater than the breakdown voltage is applied to the light receiving element 10, the element 10 enters a state in which it can operate in Geiger mode. In Geiger mode, the light receiving element 10 may experience an avalanche multiplication phenomenon in response to incident photons, generating a pulsed current. In the pixel P, a signal S10 corresponding to the photocurrent flowing through the light receiving element 10 due to the incident photons is output to the output circuit 25.

[0042] The supply circuit 21 supplies current to the light-receiving element 10, for example, when avalanche multiplication occurs and the potential difference between the electrodes of the light-receiving element 10 is smaller than the breakdown voltage. The supply circuit 21 recharges the light-receiving element 10, making it possible for the light-receiving element 10 to operate in Geiger mode again. The supply circuit 21 can also be called a recharge unit (recharge circuit). The supply circuit 21 can recharge the light-receiving element 10 with electric charge and recharge the voltage of the light-receiving element 10.

[0043] The output circuit 25 is configured to generate a signal S20 based on the signal S10 generated by the light receiving element 10. The output circuit 25 can output the signal S20 as a voltage signal based on the current of the light receiving element 10. The output circuit 25 is configured, for example, by an inverter (INV).

[0044] The output circuit 25 has, for example, an input section 26 and an output section 27, and can output an inverted signal of an input signal. In the example shown in Fig. 3A, the output circuit 25 is configured by an INV circuit (inverter circuit). The INV circuit is configured by, for example, a PMOS transistor and an NMOS transistor connected in series between the potential line L11 and a reference potential line. In the example shown in Fig. 3A, the reference potential line is a ground line.

[0045] The input section 26 of the output circuit 25 is electrically connected to, for example, the cathode of the light receiving element 10 and the supply circuit 21. In the example shown in FIG. 3A , the input section 26 of the output circuit 25 (i.e., the INV circuit) is electrically connected to a node N1 that connects the light receiving element 10 and the supply circuit 21.

[0046] The output circuit 25 receives a signal S10 from the light-receiving element 10. The signal level of the signal S10, i.e., the voltage (potential) of the signal S10, varies depending on the current flowing through the light-receiving element 10. For example, when the voltage of the signal S10 is higher than a threshold, the output circuit 25 outputs a low-level signal S20. When the voltage of the signal S10 is lower than the threshold, the output circuit 25 outputs a high-level signal S20.

[0047] 3A, the INV circuit, which is output circuit 25, transitions the voltage of signal S20 from low to high when the voltage of signal S10 becomes smaller than the threshold voltage of the INV circuit due to the reception of photons by light receiving element 10. Furthermore, when the voltage of signal S10 becomes larger than the threshold voltage of the INV circuit as a result of recharging light receiving element 10 by supply circuit 21, output circuit 25 transitions the voltage of signal S20 from high to low.

[0048] The output circuit 25 can output the signal S20, which becomes a pulse signal, as a pixel signal to the signal processing unit 112 (see FIG. 1 ). In the solid-state imaging device 1, for example, the signal S20, which becomes a pulse signal based on the voltage of the signal S10, is output as a pixel signal to the signal processing unit 112 via the signal line L2.

[0049] The output circuit 25 may be configured with a buffer circuit, an AND circuit, a NAND circuit, an OR circuit, a NOR circuit, etc. The output circuit 25 may also be configured to include a counter circuit, a TDC (Time to Digital Converter) circuit, etc. The output circuit 25 may also include a circuit that controls the supply circuit 21.

[0050] 3B is a diagram showing another example of the configuration of a pixel of the solid-state imaging device according to the embodiment. As shown in the example of FIG. 3B, the readout circuit 20 may have an output control circuit 22. As an example, the output control circuit 22 is configured with a transistor M2 and is electrically connected to a node N1 that connects the light receiving element 10 and the supply circuit 21. In the example shown in FIG. 3B, the transistor M2 is an N-type transistor (e.g., an NMOS transistor).

[0051] The output control circuit 22 (output control unit) is configured to be able to control the output of a signal from the light receiving element 10. The output control circuit 22 is controlled by a signal input to the gate of the transistor M2, and can control the timing of reading out the signal from the light receiving element 10. For example, when the transistor M2 of the output control circuit 22 is in the off state, a signal S10 corresponding to the reception of a photon can be output to the output circuit 25. The output control circuit 22 can also be considered a selection circuit (selection unit) configured to be able to select a pixel P to be read out.

[0052] FIG. 4 is a diagram showing another example of the configuration of a pixel of a solid-state imaging device according to an embodiment. As an example, a pixel P may have the circuit configuration shown in FIG. 4. The light-receiving element 10 of the pixel P is a photoelectric conversion unit (photoelectric conversion element) configured to be able to generate electric charges by photoelectric conversion. In the example shown in FIG. 4, the light-receiving element 10 is a photodiode (PD) that converts incident light into electric charges. The light-receiving element 10 can perform photoelectric conversion to generate electric charges according to the amount of received light.

[0053] The readout circuit 20 is configured to be able to output a signal based on the charge obtained by photoelectric conversion. The readout circuit 20 includes, for example, a transistor TG, a floating diffusion FD, a transistor AMP, a transistor SEL, and a transistor RST. The readout circuit 20 can read out a pixel signal based on the charge obtained by photoelectric conversion in the light receiving element 10.

[0054] The transistor TG is a transfer transistor and is configured to be able to transfer charge photoelectrically converted by the light-receiving element 10 to the floating diffusion FD. The transistor TG is controlled by a signal STG to electrically connect or disconnect the light-receiving element 10 and the floating diffusion FD. The transistor TG can transfer charge photoelectrically converted and accumulated in the light-receiving element 10 to the floating diffusion FD.

[0055] The floating diffusion FD is an accumulation section configured to be able to accumulate transferred charges. The floating diffusion FD can accumulate charges photoelectrically converted by the light receiving element 10. The floating diffusion FD can also be considered a holding section capable of holding the transferred charges. The floating diffusion FD accumulates the transferred charges and converts them into a voltage according to the capacitance of the floating diffusion FD.

[0056] The transistor AMP is configured to generate and output a signal based on the charge accumulated in the floating diffusion FD. The transistor AMP is an amplifying transistor and can generate and output a signal based on the charge converted by the light receiving element 10.

[0057] 4, the gate of the transistor AMP is electrically connected to the floating diffusion FD, and the voltage converted by the floating diffusion FD is input to the gate of the transistor AMP. The drain of the transistor AMP is connected to a power supply line that supplies a power supply voltage (power supply voltage VDD in the example shown in FIG. 4).

[0058] The source of the transistor AMP is connected to a signal line L2 via a transistor SEL. The transistor AMP is configured to generate a signal based on the charge accumulated in the floating diffusion FD, i.e., a signal based on the voltage of the floating diffusion FD, and output the signal to the signal line L2.

[0059] The transistor SEL is configured to be able to control the output of a pixel signal. The transistor SEL is electrically connected in series to the transistor AMP, for example, as in the example shown in FIG. 4. The transistor SEL is controlled by a signal SSEL and is configured to be able to output a signal from the transistor AMP to a signal line L2. The transistor SEL is a selection transistor and can control the output timing of the pixel signal.

[0060] The transistor SEL is configured to be able to output a signal based on the charge converted by the light receiving element 10. The transistor SEL can output a pixel signal of the pixel P to a signal line L2. The transistor SEL may be electrically connected in series between the transistor AMP and a power supply line to which a power supply voltage (power supply voltage VDD in FIG. 4) is applied. The transistor SEL may also be omitted as necessary.

[0061] The transistor RST is configured to be able to reset the voltage of the floating diffusion FD. In the example shown in Fig. 4, the transistor RST is electrically connected to a power supply line to which a power supply voltage VDD is applied, and is configured to reset the charge of the pixel P. The transistor RST is a reset transistor.

[0062] The transistor RST is controlled by a signal SRST to reset the charge accumulated in the floating diffusion FD and reset the voltage of the floating diffusion FD. The transistor RST electrically connects the power supply line and the floating diffusion FD and can discharge the charge accumulated in the floating diffusion FD. The transistor RST can also discharge the charge accumulated in the light receiving element 10 via the transistor TG.

[0063] The above-mentioned transistor TG (transfer transistor), transistor AMP (amplification transistor), transistor SEL (selection transistor), and transistor RST (reset transistor) are each a MOS transistor (MOSFET) having a gate, a source, and a drain terminal. In the example shown in Figure 4, the transistors TG, AMP, SEL, and RST are each composed of an NMOS transistor. Note that the transistor of pixel P may also be composed of a PMOS transistor.

[0064] The pixel control unit 111 (see FIG. 1 ) of the solid-state imaging device 1 supplies control signals to the gates of the transistors TG, SEL, RST, etc. of each pixel P via the control lines L1 described above, turning the transistors on (conducting state) or off (non-conducting state). As an example, the plurality of control lines L1 for each pixel row of the solid-state imaging device 1 include a line that transmits a signal STG that controls the transistor TG, a line that transmits a signal SSEL that controls the transistor SEL, a line that transmits a signal SRST that controls the transistor RST, etc.

[0065] The transistors TG, SEL, and RST are controlled to be turned on and off by the pixel control unit 111. The pixel control unit 111 controls the readout circuit 20 of each pixel P, for example, to output a pixel signal from each pixel P to the signal line L2. The pixel control unit 111 can control the reading out of the pixel signal of each pixel P to the signal line L2.

[0066] [Configuration Example of Image Sensor] Fig. 5A is a diagram showing an example of a cross-sectional configuration of a solid-state image sensor according to an embodiment. Each pixel P of the solid-state image sensor 1 may have, for example, the structure shown in Fig. 5A. The solid-state image sensor 1 (photodetector element) is configured using a light absorption layer 30. The light absorption layer 30 is, for example, a light absorption layer containing silicon, and is configured by a semiconductor layer containing silicon.

[0067] 5A , the solid-state imaging element 1 has a lens 80, a light absorbing layer 30, and a wiring layer 90. The solid-state imaging element 1 has a configuration in which the lens 80, the light absorbing layer 30, and the wiring layer 90 are stacked in the Z-axis direction. The lens 80, the light absorbing layer 30, and the wiring layer 90 are provided from the light incident side.

[0068] The light absorbing layer 30 is formed of a semiconductor substrate such as a silicon (Si) substrate or an SOI (Silicon On Insulator) substrate. The light absorbing layer 30 may be formed of silicon germanium (SiGe), Ge, or other semiconductor materials. The light absorbing layer 30 may be formed of a III-V group compound semiconductor material, etc.

[0069] As shown in Fig. 5A , the light absorbing layer 30 has a surface 11S1 and a surface 11S2. The surface 11S2 is the surface opposite to the surface 11S1. For example, the surface 11S1 of the light absorbing layer 30 is a light receiving surface (light incident surface). As shown in the example of Fig. 5A , the light absorbing layer 30 has the surface 11S1 as the light receiving surface, on which a recess 70 is provided. The recess 70 is a recessed portion and has, for example, an inverted pyramid shape.

[0070] The surface 11S2 of the light absorbing layer 30 is an element formation surface on which elements such as transistors are formed. A gate electrode, a gate insulating film (e.g., a gate oxide film), etc. may be provided on the surface 11S2 of the light absorbing layer 30. Note that the surface 11S2 is a surface on which various circuit elements such as transistors, resistors, or capacitors are provided, and can also be called a circuit surface.

[0071] 5A , a lens 80 is provided on the surface 11S1 (light-receiving surface) side of the light absorbing layer 30. The lens 80 is provided by being stacked on the light absorbing layer 30 in a thickness direction perpendicular to the surface 11S1 of the light absorbing layer 30. A wiring layer 90 is provided on the surface 11S2 side of the light absorbing layer 30. The lens 80 is provided on the side where light from the optical system is incident, and the wiring layer 90 is provided on the side opposite to the side where the light is incident.

[0072] In the light absorbing layer 30, a plurality of light receiving elements 10 are provided along the surfaces 11S1 and 11S2 of the light absorbing layer 30. For example, a plurality of light receiving elements 10 are embedded in the light absorbing layer 30. The light receiving elements 10 are provided between the surfaces 11S1 and 11S2 of the light absorbing layer 30. The light receiving elements 10 can also be referred to as photoelectric conversion regions. The light receiving elements 10 photoelectrically convert light incident through the lens 80.

[0073] The wiring layer 90 is provided by being stacked on the light absorption layer 30. The wiring layer 90 includes, for example, a conductor film and an insulating film, and has a plurality of wirings and vias. The wiring layer 90 has a configuration in which a plurality of wirings are stacked via an insulating film serving as an interlayer insulating film (interlayer insulating layer). The wiring layer 90 is a multi-layer wiring layer, and includes, for example, two or more layers of wirings, or three or more layers of wirings.

[0074] The wiring of the wiring layer 90 is formed using a metal material such as aluminum (Al), tungsten (W), or copper (Cu). The wiring of the wiring layer 90 may be formed using polysilicon (Poly-Si) or other conductive materials. The interlayer insulating film is formed using, for example, silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiON), or the like.

[0075] On the surface 11S2 side of the light absorption layer 30 and on the wiring layer 90, for example, the above-described readout circuit 20 (see FIG. 3A etc.) is provided for each pixel P or for each set of pixels P. In addition, the above-described pixel control unit 111, signal processing unit 112, control unit 113 (see FIG. 1), etc. may be provided on the light absorption layer 30 and the wiring layer 90, or on a substrate separate from the light absorption layer 30.

[0076] The lens 80 is a lens that focuses light and is an optical component also called an on-chip lens. The lens 80 is made of, for example, silicon oxide, silicon nitride, silicon oxynitride, or the like. The lens 80 may also be made of other light-transmitting materials. The lens 80 is provided above the light-receiving element 10, for example, for each pixel P or for each set of multiple pixels P.

[0077] Light from an object to be measured is incident on the lens 80 (lens unit) via an optical system such as an imaging lens. The lens 80 guides the incident light to the light receiving element 10. The light receiving element 10 photoelectrically converts the light incident via the lens 80. The light receiving element 10 can absorb the incident light and generate an electric charge.

[0078] The solid-state imaging device 1 may have a filter configured to selectively transmit light of a specific wavelength range from among incident light. The filter is a filter that transmits infrared light, for example, a filter that transmits near-infrared light (NIR light), and is provided above the light receiving element 10.

[0079] The filter for the pixel P may be an RGB color filter, a complementary color filter, or the like. The filter may be formed above the light absorption layer 30. The filter may be provided between the lens 80 and the light receiving element 10 for each pixel P or for each set of pixels P, for example.

[0080] 5A , the light absorption layer 30 (semiconductor layer) has semiconductor regions 40, 41, 42 and semiconductor regions 45, 46. The semiconductor region 40 is, for example, an n-type semiconductor region and an n-type well (n-well). Note that the semiconductor region 40 may also be a p-type semiconductor region serving as a p-type well region.

[0081] The semiconductor region 41 and the semiconductor region 42 are provided in, for example, the semiconductor region 40. It can also be said that the semiconductor region 41 and the semiconductor region 42 are arranged to replace part of the semiconductor region 40. The semiconductor region 41 and the semiconductor region 42 have different conductivity types.

[0082] The semiconductor region 41 is, for example, a p-type semiconductor region and is a region formed using p-type impurities. The semiconductor region 41 is a p-type diffusion region and can also be called a p-type conductive layer. The semiconductor region 42 is an n-type semiconductor region and is a region formed using n-type impurities. The semiconductor region 42 is an n-type diffusion region and can also be called an n-type conductive layer.

[0083] 5A, the light receiving element 10 includes a semiconductor region 41 and a semiconductor region 42, and has a multiplication region 47 (multiplication portion) capable of avalanche multiplication. The multiplication region 47 is formed of, for example, a p-type semiconductor region 41 and an n-type semiconductor region 42.

[0084] 5A , the semiconductor region 45 is provided from the surface 11S2 side to the surface 11S1 side of the light absorbing layer 30. The semiconductor region 46 is provided on the surface 11S2 side of the light absorbing layer 30. The semiconductor region 45 and the semiconductor region 46 have mutually different conductivity types.

[0085] The semiconductor region 45 is, for example, a p-type semiconductor region and is a region formed using p-type impurities. The semiconductor region 45 is a p-type diffusion region and can also be called a p-type conductive layer. The semiconductor region 46 is an n-type semiconductor region and is a region formed using n-type impurities. The semiconductor region 46 is an n-type diffusion region and can also be called an n-type conductive layer.

[0086] As an example, the semiconductor region 45 has an impurity concentration higher than that of the semiconductor region 41, and is a p+ type (or p++ type) semiconductor region. The semiconductor region 46 has an impurity concentration higher than that of the semiconductor region 42, and is an n+ type (or n++ type) semiconductor region.

[0087] 5A , the semiconductor region 45 is provided in contact with the semiconductor region 41 and is electrically connected to the semiconductor region 41. The p-type semiconductor region 41 and the p-type semiconductor region 45 are the anode region of the light-receiving element 10. The semiconductor region 45 can also be said to be the anode electrode of the light-receiving element 10.

[0088] The semiconductor region 46 is provided in contact with the semiconductor region 42 and is electrically connected to the semiconductor region 42. The n-type semiconductor region 42 and the n-type semiconductor region 46 form the cathode region of the light-receiving element 10. The semiconductor region 46 can also be said to be the cathode electrode of the light-receiving element 10.

[0089] 5A , the solid-state imaging device 1 has an isolation region 60. The isolation region 60 is provided, for example, around the pixel P (or the light-receiving element 10). The isolation region 60 is provided between adjacent pixels P in the light absorption layer 30, and separates the pixels P (or the light-receiving elements 10). The solid-state imaging device 1 has an element isolation structure using the isolation region 60.

[0090] The isolation region 60 is configured using a trench (groove portion). At least a part of the isolation region 60 (isolation portion) is provided at the boundary between adjacent pixels P. The isolation region 60 can be provided in the light absorption layer 30 so as to surround the light receiving element 10. The isolation region 60 is formed in the light absorption layer 30 in a lattice shape so as to surround the light receiving element 10 of each pixel P, for example.

[0091] 5A , the isolation region 60 is provided around the recess 70 on the surface 11S1 of the light absorbing layer 30. The isolation region 60 may be provided so as to surround the recess 70 in a plan view. The isolation region 60 may have, for example, a full trench isolation (FTI) structure and may be provided so as to penetrate the light absorbing layer 30. That is, the isolation region 60 may be formed so as to reach the surface 11S2 of the light absorbing layer 30.

[0092] The isolation region 60 includes, for example, a medium 62 and a metal material 65. The medium 62 and the metal material 65 are provided in the trench of the isolation region 60. For example, as in the example shown in FIG. 5A , the medium 62 and the metal material 65 can be provided so as to fill the trench of the isolation region 60.

[0093] The medium 62 is, for example, an oxide film such as silicon oxide. At least a portion of the medium 62 is provided in the light absorption layer 30 so as to follow the sidewall (side surface) of the isolation region 60. In the isolation region 60, the medium 62 can be formed so as to cover the inner surface of the trench. The medium 62 is a member provided so as to fill the trench of the isolation region 60, and can also be called a filling member.

[0094] The medium 62 is configured to have a refractive index different from that of the light absorbing layer 30. For example, the medium 62 has a refractive index lower than that of the light absorbing layer 30. The medium 62 is made of a material that has a refractive index lower than that of the material that makes up the light absorbing layer 30, for example, silicon. As an example, the medium 62 can be made of a dielectric material that has a refractive index lower than that of silicon.

[0095] An insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or an aluminum oxide film may be provided as a medium 62 within the trench of the isolation region 60. The medium 62 may also be formed using other materials having a low refractive index. Note that at least a portion of the medium 62 (filler member) may include voids (cavities) and may have a hollow structure.

[0096] The metal material 65 is provided so as to be embedded in the trench of the isolation region 60. The metal material 65 is made of tungsten (W), aluminum (Al), or the like. The metal material 65 may be made of, for example, an alloy containing tungsten as a main component or an alloy containing aluminum as a main component.

[0097] The metal material 65 may be formed using other metal materials such as Ti (titanium), Cu (copper), Ag (silver), etc. Furthermore, for example, the metal material 65 may be made of an AlCu (aluminum copper) alloy. The metal material 65 may also be made of other metal compounds (metal oxides, metal nitrides, etc.).

[0098] The metal material 65 is a structure made of a metal material such as tungsten or aluminum, and can be considered a metal member. A medium 62 can be provided around the metal material 65. The medium 62 is provided, for example, so as to cover the periphery of the metal material 65 (metal member). The medium 62 can be arranged along the side surface of the metal material 65, as in the example shown in FIG. 5A .

[0099] The separation region 60 may be provided with a plurality of metal materials (e.g., metal materials 65a, 65b) as the metal material 65. For example, as shown in Fig. 5B or 5C, the separation region 60 has a metal material 65a and a metal material 65b provided around the metal material 65a. As an example, the separation region 60 has a layered structure of the metal material 65 including the outer metal material 65b and the inner metal material 65a.

[0100] For example, the metal material 65b is provided so as to surround the metal material 65a. The metal material 65b can be formed so as to cover the side surface (side portion) of the metal material 65a. The metal material 65a can be said to be provided within the metal material 65b and to be disposed by replacing a part of the metal material 65b. The metal materials 65a and 65b are made of different materials.

[0101] The metal material 65a may be made of, for example, a material having a small thermal expansion coefficient and being resistant to temperature changes, such as tungsten or titanium.

[0102] The metal material 65b may be made of, for example, a material having high reflectivity from the visible wavelength band to the near-infrared wavelength band, such as aluminum or a metal containing aluminum as a main component (e.g., AlCu). Note that the metal materials 65a and 65b may each be made of another metal material.

[0103] In the solid-state imaging device 1, the provision of the separation region 60 can suppress unnecessary light from leaking into the surrounding pixels P and can suppress crosstalk between pixels. It is possible to suppress the leakage of light into the surrounding pixels P and suppress the occurrence of color mixing.

[0104] 5A , the light absorbing layer 30 of the solid-state imaging device 1 has a recess 70. The recess 70 is provided on the surface 11S1 (light receiving surface) side of the light absorbing layer 30. The surface 11S1 of the light absorbing layer 30 has the recess 70 provided by, for example, recessing the light absorbing layer 30. In other words, the solid-state imaging device 1 has a recessed structure on the light receiving surface of the light absorbing layer 30.

[0105] The recess 70 is a recessed portion of the light absorption layer 30 and is formed, for example, to have an inverted pyramid structure. As shown in the example of FIG. 5A , the recess 70 may have a triangular (inverted triangular) cross-sectional shape. The recess 70 may be recessed in the Z-axis direction and provided so as to reach the multiplication region 47 of the light receiving element 10. The recess 70 may be provided in contact with the multiplication region 47.

[0106] The recess 70 has, for example, a quadrangular pyramid shape including a bottom surface S1 formed on the lens 80 side. As an example, the recess 70 has a shape including the bottom surface S1 configured by the (100) plane of the silicon that configures the light absorbing layer 30. The recess 70 may also have a surface S2 configured by the (111) plane of the silicon that configures the light absorbing layer 30.

[0107] 5A, the surface S2 of the recess 70 is, for example, a slope inclined at approximately 54.7 degrees with respect to the (100) plane of silicon. The angle formed between the bottom surface S1 of the recess 70 and the surface S2 is approximately 54.7 degrees. Note that the shape and number of the recesses 70 are not limited to the example shown in the figure and can be changed as appropriate.

[0108] The apex of the recess 70 may be rounded. The recess 70 may have rounded corners. The recess 70 may be substantially pyramidal or substantially quadrangular pyramidal, as long as it can achieve predetermined performance (e.g., light refraction characteristics). The rounded tip of the recess 70 can alleviate electric field concentration at the tip, which can contribute to reducing dark current noise.

[0109] A medium 61 is provided in the recess 70 of the light absorption layer 30. The medium 61 is provided so as to fill the recess 70 having an inverted pyramid shape, for example. The medium 61 is, for example, an oxide film such as silicon oxide. The medium 61 is a member provided so as to fill the recess 70, and can also be called a filling member. The recess 70 having the medium 61 can also be called a structure or a concave-convex structure.

[0110] The medium 61 is configured to have a refractive index different from that of the light absorbing layer 30. For example, the medium 61 has a refractive index lower than that of the light absorbing layer 30. The medium 61 is made of a material that has a refractive index lower than that of the material that constitutes the light absorbing layer 30, for example, silicon.

[0111] The recess 70 may be provided with an insulating film, such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or an aluminum oxide film, as the medium 61. The medium 61 may also be made of other low refractive index materials. At least a portion of the medium 61 (filler member) may include voids and have a hollow structure.

[0112] 5A , the medium 61 and the medium 62 are formed continuously and integrally. A portion of the medium 61 is provided in the recess 70, and another portion of the medium 61 is provided in the separation region 60 as the medium 62. The medium 62 can also be considered a portion of the medium 61.

[0113] The medium 61 and the medium 62 can be collectively referred to as the medium 61 or the filling member. The lens 80 may be made of the same material as the medium 61, or may be made of a material different from the material of the medium 61. The materials of the media 61 and 62 and the material of the lens 80 can be selected depending on the wavelength range of the incident light to be measured, the material of the light absorption layer 30, etc.

[0114] 5D or 5E , the solid-state imaging device 1 may have a fixed charge film 66 on the surface 11S1 side of the light absorbing layer 30. The fixed charge film 66 is provided, for example, along the recesses 70 of the light absorbing layer 30. The fixed charge film 66 is, for example, made of a metal compound (metal oxide, metal nitride, etc.).

[0115] A portion of the fixed charge film 66 may be provided in the light absorption layer 30 so as to extend along the sidewall (side surface) of the isolation region 60. The fixed charge film 66 is a film having a fixed charge and may be formed using a high dielectric material. For example, the fixed charge film 66 is made of a metal oxide such as aluminum oxide or hafnium oxide. The fixed charge film 66 is, for example, a film having a negative fixed charge.

[0116] In the solid-state imaging device 1, the fixed charge film 66 is provided to suppress the generation of dark current at the interface of the light absorption layer 30. The fixed charge film 66 may be made of another metal oxide film, or may be made using a metal nitride film or a metal oxynitride film. The fixed charge film 66 may also be made using other materials. A film having a positive fixed charge may be provided as the fixed charge film 66.

[0117] Light from an object to be measured is incident on the recess 70 of the light absorption layer 30 via the lens 80. The recess 70 has a size (width, depth, etc.) that is equal to or greater than a predetermined wavelength of the incident light. The width and depth of the recess 70 may be equal to or greater than the wavelength of near-infrared light, for example, 940 nm.

[0118] The recess 70 has a size equal to or larger than the effective wavelength of the light to be measured. For example, the width of the recess 70 on the surface 11S1 serving as the light receiving surface is greater than the effective wavelength of near-infrared light (NIR light) in the medium 61 (i.e., the wavelength of near-infrared light in air / the refractive index of the medium 61). In addition, the depth of the recess 70 (i.e., the length in the Z-axis direction) may be greater than the effective wavelength of near-infrared light in the medium 61.

[0119] The recess 70 may be configured, for example, to be sufficiently larger than the effective wavelength of the light to be measured in the medium 61. As an example, the width of the recess 70 on the surface 11S1 may be 1000 nm or more and 9 μm or less. The depth of the recess 70 may be 700 nm or more and 6.35 μm or less.

[0120] In the solid-state imaging device 1 according to the present embodiment, the provision of the recess 70 as described above allows the incident light to be refracted. For example, the recess 70, which is larger than the effective wavelength of the light to be measured, adjusts the propagation direction of the light incident on the recess 70, and can guide the light toward the separation region 60. This can prevent the incident light from passing through the light absorption layer 30 as zero-order light, thereby improving quantum efficiency (QE). This makes it possible to improve sensitivity to incident light.

[0121] 6 is a diagram illustrating an example of the configuration of a solid-state imaging device according to a comparative example. In the case of a solid-state imaging device having a minute uneven structure on the light-receiving surface, as shown by the arrows in FIG. 6, the zero-order light component may become large, and the amount of light absorbed by the light absorption layer may decrease. It is considered that the optical path length cannot be increased, and the light utilization efficiency may decrease. For example, a decrease in quantum efficiency in the infrared region may occur.

[0122] In this embodiment, as shown by the arrow in Fig. 7, a relatively large recess 70 is provided in which a medium 61 having a refractive index different from that of the light absorbing layer 30 is provided, and light incident on the recess 70 can be split. The traveling direction of the incident light can be changed, and the zero-order light component can be reduced. It is also possible to prevent incident light from being transmitted through the light absorbing layer 30 without being absorbed.

[0123] The pixel P of the solid-state imaging device 1 has a light confinement structure including a recess 70 and an isolation region 60. As shown by the arrow in Fig. 8, light refracted by the recess 70 can be reflected by the isolation region 60, thereby lengthening the optical path length of the incident light. This increases the amount of light absorbed by the light absorption layer 30, thereby improving quantum efficiency.

[0124] The recesses 70 of the light absorption layer 30 are configured to be significantly larger than the effective wavelength of the light to be measured, for example, the effective wavelength of near-infrared light in the medium 61. The recesses 70 as structures geometrically refract the incident light, thereby suppressing the linear light component corresponding to the zeroth-order term and further enhancing the confinement effect. This makes it possible to improve the QE in the near-infrared region.

[0125] The size of the recess 70 is significantly larger than the effective wavelength of near-infrared light (e.g., 940 nm) in the medium 61. Therefore, light incident on the recess 70 having an inverted pyramid shape is refracted by the side surface of the inverted pyramid (i.e., surface S2), splitting to the left and right, and propagating through the light absorbing layer 30. Because the refracted light has a large angle with respect to surface 11S2 of the light absorbing layer 30, it satisfies the total reflection condition and can prevent light from escaping below surface 11S2. This can improve light confinement performance.

[0126] The solid-state imaging device 1 may have wiring 95, as in the example shown in Fig. 8. The wiring 95 is formed in the wiring layer 90 on the surface 11S2 side of the light absorption layer 30. The wiring 95 is provided corresponding to the semiconductor region 46 and is electrically connected to the semiconductor region 46. In the example shown in Fig. 8, the wiring 95 is part of the cathode electrode and can also be called cathode wiring.

[0127] The wiring 95 is made of, for example, a metal material and can function as a reflective member (reflector). The wiring 95 can be provided below the light receiving element 10 so as to extend in the X-axis direction (or the Y-axis direction). By arranging the wiring 95 as a reflector, it is possible to reflect light toward the light receiving element 10, thereby improving, for example, PDE (Photon Detection Efficiency).

[0128] Furthermore, in this embodiment, it is possible to suppress the occurrence of unnecessary reflected light above the light absorption layer 30 (or the lens 80). It is possible to suppress the incorporation of noise caused by unnecessary reflected light into pixel signals. Furthermore, by digging out the light absorption layer 30 to provide the large recesses 70, the travel distance of photoelectrically converted charges is reduced, making it possible to improve jitter (i.e., fluctuations in the time direction) of pixel signals.

[0129] 9A and 9B are diagrams illustrating an example of the configuration of an imaging device according to an embodiment. Fig. 9A shows an example of a cross-sectional configuration of the solid-state imaging element 1, and Fig. 9B shows an example of a planar configuration of the solid-state imaging element 1. The width W of the recess 70 on the light receiving surface may be greater than, for example, the effective wavelength of near-infrared light in the medium 61.

[0130] For example, the width W of the recess 70 on the surface 11S1 serving as the light-receiving surface may be in the range of 1000 nm to 4000 nm. For example, the length of one side of the base of the recess 70 having an inverted pyramid shape corresponds to the width W of the recess 70 and is set to be greater than the effective wavelength of near-infrared light in the medium 61. For example, the length of one side of the bottom surface of the inverted pyramid (i.e., the bottom surface S1) may be in the range of 1000 nm to 4000 nm.

[0131] Furthermore, the depth d of the recess 70 may be, for example, greater than the effective wavelength of near-infrared light in the medium 61. For example, the depth d of the recess 70 may be 700 nm or more and 3000 nm or less. By configuring the solid-state imaging device 1 in this manner, it is possible to effectively improve the quantum efficiency in the near-infrared region. It is also possible to effectively improve the sensitivity to near-infrared light.

[0132] The thickness in the X-axis direction (or Y-axis direction) of the part of the medium 61 provided around the metal material 65, i.e., the medium 62, may be, for example, 100 nm or more. The medium 62 is, for example, an insulating film (such as a silicon oxide film, a silicon oxynitride film, or an aluminum oxide film) having a refractive index lower than that of silicon.

[0133] 9A , the thickness t (film thickness) of the medium 62 may be 100 nm or more. In this case, it is possible to mitigate the interaction between the metal material 65 and the near-field light that seeps out when light is totally reflected at the boundary surface between the medium 62 and the silicon portion (e.g., the semiconductor region 45). This makes it possible to reduce the loss of light and prevent a decrease in quantum efficiency.

[0134] The thickness t of the medium 62 may be 150 nm or more. This makes it possible to effectively suppress a decrease in quantum efficiency. The thickness t (film thickness) of the medium 62 may be within a range of 150 nm or more and 250 nm or less. The thickness t of the medium 62 may be, for example, approximately 200 nm.

[0135] The medium 61 and the medium 62 may be formed integrally, or may be formed separately as in the example shown in Figure 10A or 10B. The medium 61 and the medium 62 may be made of different dielectric materials. The thickness t of the medium 62 in the X-axis direction (or Y-axis direction) may be, for example, 100 nm or more and 300 nm or less.

[0136] 11 is a block diagram illustrating an example of a schematic configuration of a light detection system according to an embodiment of the present disclosure. The light detection system 200 includes, for example, the above-described solid-state image sensor 1 (light detection element), a light source control unit 210, and a light source 220, as shown in the example of FIG.

[0137] The light source 220 is configured to be capable of generating light (optical signals). The light source 220 has, for example, one or more light-emitting elements and is configured to be capable of irradiating the measurement object with light. The light-emitting element is an LD (Laser Diode), an LED (Light Emitting Diode), or the like, and can output light (infrared light, visible light, etc.) to the outside.

[0138] The light source 220 (light source unit) may generate laser light and emit the laser light to the outside. The light source 220 may be configured using a semiconductor laser element, for example, a vertical cavity surface emitting laser (VCSEL).

[0139] The light source control unit 210 is configured to be able to control the light source 220. The light source control unit 210 is a drive unit (drive circuit) configured to drive the light source 220. The light source control unit 210 is configured by a plurality of circuits including, for example, a digital-to-analog converter (DAC), an amplifier circuit, etc., and can control the operation of the light source 220.

[0140] The light source control unit 210 is configured to be able to control, for example, the current and voltage to the light emitting elements of the light source 220. The light source control unit 210 supplies the light source 220 with the current and voltage for driving the light emitting elements of the light source 220, and can control the light emission by the light source 220 (for example, the light emission timing, the light emission duration, etc.).

[0141] The light source control unit 210 can also be said to be a light source driving unit configured to be able to drive the light source 220 (or the light emitting element of the light source 220). Note that the light source 220 and the light source control unit 210 may be partially or entirely configured as an integrated unit. For example, the light source 220 and the light source control unit 210 may be partially or entirely configured as a light source device (light source unit).

[0142] The light detection system 200 can irradiate a measurement object with light (e.g., laser light) using a light source 220 and receive the light reflected by the measurement object. In the solid-state imaging device 1, for example, reflected light (returned light) reflected by the measurement object is incident on the pixel unit 100, and an electrical signal corresponding to the reception of the reflected light is detected. The electrical signal generated by receiving the reflected light from the measurement object is a signal corresponding to the distance to the measurement object.

[0143] The light detection system 200 including the solid-state imaging device 1 can transmit and receive light and measure the distance to a measurement target. As an example, the solid-state imaging device 1 is configured to detect the distance to the object (subject) that is the measurement target for each pixel P and generate image data (distance image data) related to the distance to the object. The solid-state imaging device 1 can generate, for example, a depth map.

[0144] The solid-state imaging device 1 (photodetection device) can also be applied as a sensor capable of detecting an event, for example, an event-driven sensor (also called an EVS (Event Vision Sensor), an EDS (Event Driven Sensor), or a DVS (Dynamic Vision Sensor)). The solid-state imaging device 1 and the photodetection system 200 can be applied to various electronic devices.

[0145] [Actions and Effects] The solid-state imaging element (solid-state imaging element 1) according to this embodiment includes a light-absorbing layer (light-absorbing layer 30) that contains silicon and has a light-receiving surface (e.g., surface 11S1) on which a recess (recess 70) is provided, a separation region (separation region 60) that is provided around the recess in the light-absorbing layer, and a first medium (medium 61) that has a refractive index lower than that of silicon and is provided to fill the recess.

[0146] The solid-state imaging element 1 according to this embodiment includes a light absorption layer 30 having a recess 70, a separation region 60, and a medium 61. The medium 61 has a refractive index lower than that of silicon, and is provided so as to fill the recess 70. This makes it possible to realize a solid-state imaging element (photodetection element) capable of improving sensitivity to incident light.

[0147] In the solid-state imaging device according to this embodiment, the separation region (separation region 60) includes a metal material (metal material 65) and a portion of a first medium (medium 62) that surrounds the metal material. The thickness of the portion of the first medium (medium 62) surrounding the metal material is 100 nm or more. This reduces the interaction between near-field light (evanescent light) and the metal material 65. This also makes it possible to suppress a decrease in quantum efficiency.

[0148] In the solid-state imaging device according to the present embodiment, for example, the separation region (separation region 60) includes a metal material containing aluminum (metal material 65). By providing the metal material 65 made of aluminum, which reflects light, it is possible to improve the light confinement performance and the quantum efficiency.

[0149] In this embodiment, the separation region (separation region 60) has a metal material (metal material 65) and a second medium (medium 62) provided so as to surround the metal material. The thickness of the second medium is 100 nm or more. This can mitigate the interaction between the near-field light and the metal material 65, making it possible to suppress a decrease in quantum efficiency.

[0150] In this embodiment, for example, the separation region (separation region 60) has a first metal material (metal material 65a) and a second metal material (metal material 65b) provided around the first metal material. The first metal material includes tungsten. The second metal material includes aluminum. By configuring the separation region 60 in this manner, it is possible to improve the light confinement performance while improving resistance to external stress (e.g., thermal stress).

[0151] Next, a modified example of the present disclosure will be described. In the following, the same components as those in the above embodiment will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0152] <2. Modifications> (2-1. Modification 1) In the above-described embodiment, configuration examples of a solid-state imaging element have been described, but the configuration of the solid-state imaging element is not limited to the above-described example. FIGS. 12 and 13 are diagrams for explaining a configuration example of a solid-state imaging element according to Modification 1 of the present disclosure. As in the example shown in FIG. 12 , multiple recesses 70 may be provided for each pixel P (or light receiving element 10). For example, 2×2, or four recesses 70 may be provided for one pixel P (or light receiving element 10).

[0153] In the solid-state imaging device 1, an array of N×M recesses 70 may be provided per pixel P (or light receiving element 10). For example, N=M (e.g., N=M=2) recesses 70 having an inverted pyramid shape may be formed per pixel P. N is, for example, an integer smaller than 5. M may also be an integer smaller than 5. Note that N may not be equal to M.

[0154] 13 , a lens 80 may be provided for each recess 70. One lens 80 may be arranged for one recess 70. By configuring the solid-state imaging device 1 in this manner, light can be appropriately focused onto the recess 70, and the light refraction effect of the recess 70 can be improved.

[0155] (2-2. Modification 2) Fig. 14 is a diagram for explaining a configuration example of a solid-state imaging element according to modification 2. The size of the recess 70 may be set according to the size of the light spot focused by the lens 80. For example, as in the example schematically shown by the dashed line in Fig. 14, the width W1 of the recess 70 on the light receiving surface may be approximately the same as the size of the light spot focused by the lens 80.

[0156] (2-3. Modification 3) Figures 15A and 15B are diagrams for explaining an example of the configuration of a solid-state imaging element according to Modification 3. Figures 15A and 15B show example cross-sectional configurations at positions of different image heights of the solid-state imaging element. Figure 15B shows an example of the cross-sectional configuration in a region where the distance from the center of the pixel unit 100, i.e., the image height, is higher than in the case of Figure 15A.

[0157] For example, light from an optical lens is incident almost perpendicularly on the central portion of the pixel unit 100 of the solid-state imaging device 1. Light is incident obliquely on the peripheral portion located outside the central portion, i.e., on the region farther from the center of the pixel unit 100, as shown by the example schematically indicated by the arrows in Fig. 15B. Therefore, in the solid-state imaging device 1, the position of the recess 70 in each pixel P can be configured to vary depending on the distance from the center of the pixel unit 100, i.e., the image height.

[0158] 15B , the recess 70 in the light receiving surface is, for example, shifted with respect to the light receiving element 10 (or the lens 80) on the opposite side from the center of the pixel unit 100. In the example shown in FIG. 15B , the recess 70 can also be said to be shifted leftward with respect to the light receiving element 10 and the lens 80 of the pixel P.

[0159] In the pixel section 100 of the solid-state imaging device 1, the position of the recess 70 is adjusted according to the image height, allowing for appropriate pupil correction. This prevents a decrease in the amount of light incident on the light receiving element 10 of each pixel P, thereby preventing a decrease in sensitivity to incident light. This makes it possible to improve the quantum efficiency of the pixels P in the high image height region.

[0160] (2-4. Modification 4) Fig. 16 is a diagram for explaining a configuration example of a solid-state imaging element according to Modification 4. As in the example shown in Fig. 16, the solid-state imaging element 1 may have a light-shielding member 67. The light-shielding member 67 is a light-shielding portion (light-shielding film) made of a material that blocks light, and is provided around a recess 70 in the light absorption layer 30. The light-shielding member 67 may be provided so as to surround the recess 70 in a plan view.

[0161] 16 , the light-shielding member 67 is located above the metal material 65 in the direction in which light is incident. The light-shielding member 67 is provided, for example, by being laminated on the metal material 65. The light-shielding member 67 is made of a metal material such as tungsten or aluminum. Note that the light-shielding member 67 may also be made of other materials.

[0162] The light-shielding member 67 may be made of a light-reflecting material, such as aluminum. By providing the light-shielding member 67 (reflecting member), incident light reflected by the light-absorbing layer 30 or the wiring layer 90 can be reflected toward the light-receiving element 10. This makes it possible to improve the light-confining performance.

[0163] 17 is a diagram illustrating another example of the configuration of a solid-state imaging device according to Modification 4. The solid-state imaging device 1 may have a medium 61 made of a highly refractive material. The medium 61 is made of, for example, a material that has a refractive index higher than that of the material that makes up the light absorption layer 30, such as silicon. As an example, the medium 61 may be made of a silicon nitride film. Note that the medium 61 may be configured to have a refractive index higher than that of the lens 80.

[0164] 17, the recess 70 having the medium 61 can appropriately focus incident light onto the light receiving element 10. This can improve the sensitivity to incident light. This can improve the light utilization efficiency.

[0165] 17, an anti-reflection film 68 may be provided above the medium 61. The anti-reflection film 68 may be made of, for example, silicon nitride, silicon oxide, aluminum oxide, or the like. In the example shown in FIG. 17, the anti-reflection film 68 (anti-reflection film) is provided between the lens 80 and the medium 61 to reduce (suppress) reflection. The anti-reflection film 68 may be made of metal oxide or may be formed using other materials.

[0166] 18 and 19 are diagrams for explaining a configuration example of a solid-state imaging element according to Modification 5. The solid-state imaging element 1 may have a structure 69 provided below the light receiving element 10. The structure 69 is a scatterer and has, for example, an STI (Shallow Trench Isolation) structure. The solid-state imaging element 1 has a plurality of structures 69 arranged side by side in the X-axis direction or the Y-axis direction, for example.

[0167] 19 , the structure 69 may be provided in the wiring layer 90. The structure 69 may be a concave-convex structure formed by dry etching or wet etching. By providing the structure 69, light that is not absorbed by the light absorption layer 30 and passes through can be reflected by the structure 69 toward the light receiving element 10. Light that travels below the light receiving element 10 can also be made to re-enter the light receiving element 10, thereby improving quantum efficiency.

[0168] (2-6. Modification 6) FIG. 20 is a diagram illustrating an example of the configuration of a solid-state imaging device according to Modification 6. The thickness t of the medium 62 in the X-axis direction (or Y-axis direction) may be, for example, 100 nm or more. In this case, it is possible to reduce the interaction between the evanescent wave and the metal material 65, and to suppress a decrease in quantum efficiency. The thickness t of the medium 62 may be 150 nm or more. This makes it possible to effectively suppress a decrease in quantum efficiency.

[0169] (2-7. Modification 7) In the above-described embodiment and modification, exemplary configurations of the lens 80 have been illustrated, but these are merely examples, and the configuration of the lens 80 is not limited to the above-described examples. The lens 80 may be, for example, a rectangular lens (digital lens) or a Fresnel lens.

[0170] The solid-state imaging device 1 may include a metalens 89, as shown in the example in FIG. 21 . The metalens 89 is an optical element that focuses light using metamaterial (metasurface) technology, and is configured using, for example, a plurality of structures 88. As an example, the structures 88 have a columnar shape and may be configured using a material that has a refractive index different from that of the surrounding medium. The structures 88 are also referred to as, for example, nanopillars, nanostructures, nanoposts, etc.

[0171] (2-8. Modification 8) FIG. 22 is a diagram illustrating a configuration example of a solid-state imaging element according to Modification 8. The solid-state imaging element 1 may have a stacked structure in which a plurality of semiconductor layers are stacked. In the example shown in FIG. 22, the solid-state imaging element 1 has a light absorbing layer 30 (semiconductor layer) and a semiconductor layer 35. The solid-state imaging element 1 has a configuration in which the light absorbing layer 30 and the semiconductor layer 35 are stacked.

[0172] For example, the readout circuit 20 described above may be provided separately in the light absorption layer 30 and the semiconductor layer 35. At least some of the transistors of the readout circuit 20 described above with reference to Fig. 3A or 4 may be provided in the semiconductor layer 35. Note that the solid-state imaging device 1 may have a structure in which three or more semiconductor layers are stacked.

[0173] The solid-state imaging device 1 may have a reflective member 85, as in the example shown in Fig. 23 . The reflective member 85 is made of a light-reflecting material, such as aluminum. The reflective member 81 (reflective film) may be made of other metal materials, a dielectric multilayer film, or the like. By providing the reflective member 85, light that passes through the light-absorbing layer 30 without being absorbed can be reflected by the reflective member 85 toward the light-receiving element 10, thereby improving quantum efficiency.

[0174] (2-9. Modification 9) FIGS. 24 and 25 are diagrams illustrating an example of the configuration of a solid-state imaging device according to Modification 9. The metal material 65 of the separation region 60 may be made of a light-reflecting material, such as aluminum. The metal material 65 may be made mainly of aluminum or silver. A thin barrier metal may also be provided on the surface of the metal material 65. By configuring the solid-state imaging device 1 in this way, it is possible to further improve the light confinement performance.

[0175] 26 and 27 are diagrams for explaining an example of the configuration of a solid-state imaging element according to Modification 10. FIG. 26 shows an example of the planar configuration of the solid-state imaging element 1, and FIG. 27 shows an example of the cross-sectional configuration of the solid-state imaging element 1. The solid-state imaging element 1 has a plurality of pixels P each including a photodiode (PD), and may be configured as a distance measurement sensor capable of performing iToF distance measurement.

[0176] The light receiving element 10 of the pixel P is configured to be capable of generating charge through photoelectric conversion. The light receiving element 10 is a photoelectric conversion element that performs photoelectric conversion to generate charge according to the amount of light received. The readout circuit 20 has, for example, multiple transistors (transfer transistor, amplification transistor, selection transistor, reset transistor, etc.) and is configured to be capable of outputting a signal based on the photoelectrically converted charge. The readout circuit 20 can read out a pixel signal based on the charge photoelectrically converted by the photoelectric conversion unit 12. In this modified example, the same effects as those of the above-described embodiment can be obtained.

[0177] 28 and 29 are diagrams illustrating another example configuration of a solid-state imaging element according to Modification 10. The isolation region 60 may be provided within a pixel P, as in the example shown in FIGS. 28 and 29 . In the example shown in FIG. 28 , recesses 70 serving as dug portions of an inverted pyramid structure are provided so as to be located at four vertices of the substantially square region of the pixel P. Some vertices of the recesses 70 may be provided between adjacent pixels P. In this case as well, as in the example schematically shown by the arrows in FIG. 29 , the recesses 70 can refract light, thereby improving quantum efficiency.

[0178] 27 or 29, the recess 70 may have a rounded shape. For example, the recess 70 may have a rounded, approximately pyramidal shape (or an approximately square pyramid shape). This can alleviate electric field concentration at the edge of the recess 70, thereby suppressing the generation of dark current.

[0179] (2-11. Modification 11) Fig. 30 is a diagram illustrating an example configuration of a solid-state imaging device according to Modification 11. The solid-state imaging device 1 can be configured as a distance measurement sensor capable of performing iToF distance measurement. The readout circuit 20 of the pixel P includes, for example, a transistor TG1, a transistor TG2, a charge storage memory MEM1, and a charge storage memory MEM2.

[0180] The transistor TG1 is a transfer transistor and is configured to be able to transfer charges photoelectrically converted by the light receiving element 10 to the charge storage memory MEM1. The transistor TG1 electrically connects or disconnects the light receiving element 10 and the charge storage memory MEM1. The transistor TG1 can transfer charges photoelectrically converted and stored in the light receiving element 10 to the charge storage memory MEM1.

[0181] The transistor TG2 is a transfer transistor and is configured to be able to transfer charges photoelectrically converted by the light receiving element 10 to the charge storage memory MEM2. The transistor TG2 electrically connects or disconnects the light receiving element 10 and the charge storage memory MEM2. The transistor TG2 can transfer charges photoelectrically converted and stored in the light receiving element 10 to the charge storage memory MEM2.

[0182] The charge storage memories MEM1 and MEM2 are each a storage unit configured to store transferred charges. The charge storage memories MEM1 and MEM2 can each store charges photoelectrically converted by the light receiving element 10. The charge storage memories MEM1 and MEM2 may each be configured by a capacitive element such as a MOS capacitor or a MIM (Metal-Insulator-Metal) capacitor.

[0183] The readout circuit 20 is configured to output a pixel signal Sig1 based on the charges stored in the charge storage memory MEM1 and a pixel signal Sig2 based on the charges stored in the charge storage memory MEM2 to the signal processing unit 112 (see FIG. 1 ). For example, by using the pixel signals Sig1 and Sig2, the signal processing unit 112 can estimate the phase difference between the irradiated light and the reflected light, i.e., the round-trip time of the light, and calculate the distance between the solid-state imaging device 1 and the object to be measured.

[0184] 31 , a plurality of recesses 70 may be provided for each pixel P (or light receiving element 10). As an example, four recesses 70 (2×2) may be provided for each pixel P. Furthermore, a lens 80 may be provided for each recess 70.

[0185] (2-12. Modification 12) FIGS. 32 and 33 are diagrams for explaining a configuration example of a solid-state imaging element according to Modification 12. In the solid-state imaging element 1, a plurality of isolation regions 60 may be provided so as to surround the recess 70. For example, a plurality of isolation regions 60 including a metal material 65 may be discretely arranged. As in the example shown in FIG. 32, a plurality of isolation regions 60 may be provided in a pinwheel shape. As in the example shown in FIG. 33, an isolation region 60 may not be provided at the cross portion (intersection portion) of four adjacent pixels P.

[0186] 3. Usage Examples The above-described solid-state imaging device 1 and light detection system 200 can be used in various cases for sensing light such as visible light, infrared light, ultraviolet light, and X-rays, for example, as follows.・Devices for taking images for viewing purposes, such as digital cameras and mobile devices with camera functions. ・Devices for traffic purposes, such as in-vehicle sensors that take images of the front, rear, surroundings, and interior of a car for safe driving such as automatic stopping, and for recognizing the driver's state, surveillance cameras that monitor moving vehicles and roads, and distance measuring sensors that measure distances between vehicles. ・Devices for home appliances such as televisions, refrigerators, and air conditioners that take images of user gestures and operate the device according to those gestures. ・Devices for medical and healthcare purposes, such as endoscopes and devices that take images of blood vessels by receiving infrared light. ・Devices for security purposes, such as surveillance cameras for crime prevention and cameras for person authentication. ・Devices for beauty purposes, such as skin measuring devices that take images of the skin and microscopes that take images of the scalp. ・Devices for sports purposes, such as action cameras and wearable cameras for sports, etc. ・Devices for agricultural purposes, such as cameras to monitor the condition of fields and crops.

[0187] 4. Application Examples (Application Examples to Mobile Bodies) The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of mobile body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0188] FIG. 34 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0189] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 34, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053.

[0190] 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.

[0191] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0192] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0193] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0194] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0195] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0196] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0197] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0198] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying information to vehicle occupants or the outside of the vehicle. In the example of Fig. 34, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0199] FIG. 35 is a diagram showing an example of the installation position of the imaging unit 12031.

[0200] In FIG. 35 , a vehicle 12100 has imaging units 12101, 12102, 12103, 12104, and 12105 as the imaging unit 12031.

[0201] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The forward images acquired by the imaging units 12101 and 12105 are mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0202] 35 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0203] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0204] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which runs autonomously without relying on driver operation.

[0205] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding 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. The microcomputer 12051 then determines a collision risk that indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0206] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0207] The above describes an example of a mobile object control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to, for example, the image capturing unit 12031 of the above-described configuration. Specifically, for example, the solid-state image sensor 1 can be applied to the image capturing unit 12031. By applying the technology according to the present disclosure to the image capturing unit 12031, high-resolution captured images can be obtained, enabling highly accurate control to be performed in the mobile object control system using the captured images.

[0208] Although the present disclosure has been described above by giving embodiments, modifications, use examples, and application examples, the present technology is not limited to the above-described embodiments, etc., and various modifications are possible. For example, although the modifications described above have been described as modifications of the above-described embodiments, the configurations of the modifications can be combined as appropriate.

[0209] The solid-state imaging element of the present disclosure may be, for example, an element that receives incident light and converts the light into an electric charge. The output signal may be a signal of image information or a signal of distance measurement information. The light detection element (imaging element) may be applied to an image sensor, a distance measurement sensor, etc.

[0210] According to an embodiment of the present disclosure, a solid-state imaging device includes a light absorbing layer including silicon and having a light receiving surface with a recess provided therein, a separation region provided around the recess in the light absorbing layer, and a first medium having a refractive index lower than that of silicon and provided to fill the recess, thereby enabling the realization of a solid-state imaging device capable of improving sensitivity.

[0211] According to an embodiment of the present disclosure, a photodetector element includes a light absorbing layer including silicon and having a light receiving surface with a recess formed therein, a separation region provided in the light absorbing layer around the recess, and a first medium having a refractive index different from that of silicon and provided to fill the recess, thereby enabling the realization of a photodetector element capable of improving sensitivity.

[0212] Note that the effects described in this specification are merely examples and are not limited to those described, and other effects may be present. The present disclosure may also have the following configurations. (1) A solid-state imaging device comprising: a light-absorbing layer containing silicon and having a light-receiving surface with a recess provided therein; an isolation region provided in the light-absorbing layer around the recess; and a first medium having a refractive index lower than that of silicon and provided to fill the recess. (2) The solid-state imaging device according to (1), comprising: a plurality of pixels each having a light-receiving element provided in the light-absorbing layer; the isolation region being provided between adjacent pixels; and a portion of the first medium being provided in the isolation region. (3) The solid-state imaging device according to (1) or (2), wherein the recess is a recessed portion having an inverted pyramid shape. (4) The solid-state imaging device according to any one of (1) to (3), wherein the light-absorbing layer is a semiconductor layer containing silicon; and the recess has a shape including a surface formed by a (111) plane of silicon. (5) The solid-state imaging device according to any one of (1) to (4), wherein the width of the recess in the light-receiving surface is greater than the effective wavelength of near-infrared light in the first medium. (6) The solid-state imaging device according to any one of (1) to (5), wherein the width of the recess in the light-receiving surface is 1000 nm or more and 4000 nm or less. (7) The solid-state imaging device according to any one of (1) to (6), wherein the depth of the recess is greater than the effective wavelength of near-infrared light in the first medium. (8) The solid-state imaging device according to any one of (1) to (7), wherein the depth of the recess is 700 nm or more and 3000 nm or less. (9) The solid-state imaging device according to any one of (1) to (8), wherein the separation region includes a metal material and a portion of the first medium provided so as to cover the periphery of the metal material. (10) The solid-state imaging device according to (9), wherein the thickness of the portion of the first medium provided around the metal material is 100 nm or more. (11) The solid-state imaging device according to (9), wherein the thickness of the portion of the first medium provided around the metal material is 150 nm or more.(12) The solid-state imaging device according to any one of (1) to (8), wherein the separation region includes a metal material and a second medium provided so as to cover the periphery of the metal material. (13) The solid-state imaging device according to (12), wherein the second medium has a refractive index lower than that of silicon. (14) The solid-state imaging device according to (12) or (13), wherein the thickness of the second medium is 100 nm or more. (15) The solid-state imaging device according to any one of (12) to (14), wherein the thickness of the second medium is 150 nm or more. (16) The solid-state imaging device according to any one of (12) to (15), wherein the thickness of the second medium is 150 nm or more and 250 nm or less. (17) The solid-state imaging device according to any one of (12) to (16), wherein the first medium and the second medium are provided integrally. (18) The solid-state imaging device according to any one of (9) to (17), wherein the metal material includes tungsten. (19) The solid-state imaging device according to any one of (9) to (17), wherein the metal material includes aluminum. (20) The solid-state imaging device according to any one of (9) to (17), wherein the separation region has, as the metal material, a first metal material and a second metal material provided around the first metal material, wherein the first metal material includes tungsten, and the second metal material includes aluminum. (21) The solid-state imaging device according to any one of (1) to (20), further including: a plurality of pixels each having a light-receiving element provided in the light absorption layer; and a lens provided above the light absorption layer. (22) The solid-state imaging device according to (21), wherein the light-receiving surface has a plurality of the recesses for each pixel, and the lens is provided for each recess or for each of the plurality of recesses. (23) The solid-state imaging device according to any one of (1) to (22), further comprising: a plurality of pixels each having a light-receiving element provided in the light absorption layer; and the separation region being provided within the pixel.(24) The solid-state imaging device according to any one of (1) to (23), comprising: a pixel having a light-receiving element provided in the light absorption layer, wherein the light-receiving element performs photoelectric conversion on light incident through the recess, and the pixel includes a first charge storage memory capable of storing charge photoelectrically converted by the light-receiving element and a second charge storage memory capable of storing charge photoelectrically converted by the light-receiving element. (25) The solid-state imaging device according to any one of (1) to (24), comprising: a pixel having a light-receiving element provided in the light absorption layer, wherein the light-receiving element is an avalanche photodiode. (26) A photodetector comprising: a light absorption layer including silicon and having a light-receiving surface on which a recess is provided; a separation region provided in the light absorption layer around the recess; and a first medium having a refractive index different from that of silicon and provided to fill the recess. (27) A light detection system comprising: a light source capable of irradiating light onto an object; and a light detection element that receives light from the object, wherein the light detection element comprises: a light absorption layer that includes silicon and has a light receiving surface in which a recess is provided; a separation region that is provided in the light absorption layer around the recess; and a first medium that has a refractive index different from the refractive index of silicon and is provided to fill the recess.

[0213] This application claims priority to U.S. Provisional Patent Application No. 63 / 533,080, filed in the U.S. Patent and Trademark Office on August 16, 2023, the entire contents of which are incorporated herein by reference.

[0214] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur depending on design requirements and other factors, and are intended to be within the scope of the appended claims and their equivalents.

Claims

1. A solid-state imaging device comprising: a light absorbing layer including silicon and having a light receiving surface with a recess provided therein; a separation region provided in said light absorbing layer around said recess; and a first medium having a refractive index lower than that of silicon and provided so as to fill said recess.

2. A solid-state imaging device as described in claim 1, comprising a plurality of pixels each having a light receiving element provided in the light absorption layer, the separation region being provided between adjacent ones of the pixels, and a portion of the first medium being provided in the separation region.

3. The solid-state imaging device according to claim 1, wherein the recess is a recessed portion having an inverted pyramid shape.

4. The solid-state imaging device according to claim 1, wherein the light absorption layer is a semiconductor layer containing silicon, and the recess has a shape including a surface formed by a (111) surface of silicon.

5. The solid-state imaging device according to claim 1, wherein the width of the recess in the light receiving surface is greater than the effective wavelength of near-infrared light in the first medium.

6. The solid-state imaging device according to claim 1, wherein the width of the recess in the light receiving surface is 1000 nm or more and 4000 nm or less.

7. The solid-state imaging device according to claim 1, wherein the depth of the recess is greater than the effective wavelength of near-infrared light in the first medium.

8. The solid-state imaging device according to claim 1, wherein the depth of the recess is 700 nm or more and 3000 nm or less.

9. The solid-state imaging element according to claim 1, wherein the separation region comprises a metal material and a part of the first medium provided so as to cover the periphery of the metal material.

10. The solid-state imaging device according to claim 9, wherein the thickness of the portion of the first medium provided around the metal material is 100 nm or more.

11. The solid-state imaging device according to claim 9, wherein the thickness of the portion of the first medium provided around the metal material is 150 nm or more.

12. The solid-state imaging device according to claim 1, wherein the separation region comprises a metal material and a second medium provided so as to surround the metal material.

13. The solid-state imaging device according to claim 12, wherein the second medium has a refractive index lower than that of silicon.

14. The solid-state imaging device according to claim 12, wherein the second medium has a thickness of 100 nm or more.

15. The solid-state imaging device according to claim 12, wherein the second medium has a thickness of 150 nm or more.

16. The solid-state imaging device according to claim 12, wherein the thickness of the second medium is 150 nm or more and 250 nm or less.

17. The solid-state imaging device according to claim 12, wherein the first medium and the second medium are integrally provided.

18. The solid-state imaging device according to claim 9, wherein the metal material includes tungsten.

19. The solid-state imaging device according to claim 9, wherein the metal material includes aluminum.

20. The solid-state imaging element of claim 9, wherein the separation region has as its metal material a first metal material and a second metal material provided around the first metal material, the first metal material including tungsten, and the second metal material including aluminum.

21. The solid-state imaging device according to claim 1, further comprising: a plurality of pixels each having a light receiving element provided in said light absorbing layer; and a lens provided above said light absorbing layer.

22. The solid-state imaging device according to claim 21, wherein the light receiving surface has a plurality of the recesses for each pixel, and the lens is provided for each recess or for each of a plurality of the recesses.

23. The solid-state imaging device according to claim 1, comprising a plurality of pixels each having a light receiving element provided in said light absorption layer, said separation region being provided within said pixel.

24. A solid-state imaging element as described in claim 1, comprising a pixel having a light receiving element provided in the light absorption layer, the light receiving element photoelectrically converting light incident through the recess, and the pixel including a first charge accumulation memory capable of accumulating electric charges photoelectrically converted by the light receiving element, and a second charge accumulation memory capable of accumulating electric charges photoelectrically converted by the light receiving element.

25. The solid-state imaging device according to claim 1, further comprising a pixel having a light receiving element provided in said light absorption layer, said light receiving element being an avalanche photodiode.

26. A photodetector comprising: a light absorbing layer including silicon and having a light receiving surface with a recess provided therein; a separation region provided in the light absorbing layer around the recess; and a first medium having a refractive index different from that of silicon and provided to fill the recess.

27. An optical detection system comprising: a light source capable of irradiating light onto an object; and an optical detection element that receives light from the object, wherein the optical detection element comprises: a light absorbing layer including silicon and having a light receiving surface with a recess provided therein; a separation region provided in the light absorbing layer around the recess; and a first medium having a refractive index different from the refractive index of silicon and provided to fill the recess.

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