Light detection device

Abstract

This light detection device comprises: a semiconductor substrate that has a photoelectric conversion element for subjecting light to photoelectric conversion; and an insulating layer that is layered on the semiconductor substrate and has at least one thin film transistor, wherein the insulating layer further has wiring that connects the thin film transistor and the semiconductor substrate, and at least a portion of the wiring is composed of the same material as a semiconductor material of the thin film transistor.

Description

Photodetector

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

[0002] In back-illuminated CMOS (Complementary Metal Oxide Semiconductor) image sensors, it is possible to increase the conversion efficiency by reducing the capacitance (FD capacitance) of the floating diffusion. Improving the conversion efficiency is expected to reduce random noise. Therefore, there is a technology that aims to achieve high conversion efficiency and low random noise by adopting a local wiring structure instead of back-end-of-line (BEOL) wiring to reduce the FD capacitance (see Patent Document 1).

[0003] International Publication No. 2016 / 199588

[0004] In the above-described local wiring structure, transistors such as a reset transistor connected to the FD by local wiring exist on the semiconductor substrate. Therefore, the capacitance of the diffusion layer in the semiconductor substrate is large. Furthermore, in the case of a fine pixel or pixel sharing structure, there are layout restrictions on the semiconductor substrate.

[0005] Therefore, it is desirable to provide a photodetector that can reduce random noise while optimizing the layout of transistors on a semiconductor substrate.

[0006] A photodetector according to one embodiment of the present disclosure includes a semiconductor substrate having a photoelectric conversion element that converts light into electricity, and an insulating layer stacked on the semiconductor substrate and having at least one thin film transistor, the insulating layer further having wiring that connects the thin film transistor to the semiconductor substrate, and at least a portion of the wiring is made of the same material as the semiconductor material of the thin film transistor.

[0007] In the photodetector according to the embodiment of the present disclosure, the insulating layer has thin film transistors and wiring, and at least a portion of the wiring is made of the same material as the semiconductor material of the thin film transistors.

[0008] FIG. 1 is a block diagram illustrating an overview of an imaging device serving as a light detection device according to an embodiment of the present disclosure. FIG. 2 is a configuration diagram illustrating an example of a pixel unit in an imaging device serving as a detection device according to an embodiment. FIG. 3 is a circuit diagram illustrating a circuit configuration of a pixel in Configuration Example 1 of an imaging device according to an embodiment. FIG. 4 is a cross-sectional view of a main portion of a pixel in Configuration Example 1 of an imaging device according to an embodiment. FIG. 5 is a plan view illustrating an example of a planar configuration of a pixel in Configuration Example 1 of an imaging device according to an embodiment. FIG. 6 is a circuit diagram illustrating a circuit configuration of a pixel in Configuration Example 2 of an imaging device according to an embodiment. FIG. 7 is a cross-sectional view of a main portion of a pixel in Configuration Example 2 of an imaging device according to an embodiment. FIG. 8 is a plan view illustrating an example of a planar configuration of a pixel in Configuration Example 2 of an imaging device according to an embodiment. FIG. 9 is a circuit diagram illustrating a circuit configuration of a pixel in Configuration Example 3 of an imaging device according to an embodiment. FIG. 10 is a cross-sectional view of a main portion of a pixel in Configuration Example 3 of an imaging device according to an embodiment. FIG. 11 is a circuit diagram illustrating a circuit configuration of a pixel in Configuration Example 4 of an imaging device according to an embodiment. Fig. 12 is a plan view showing an example of the planar configuration of a pixel in configuration example 4 of an imaging device according to an embodiment. Fig. 13 is a cross-sectional view of a main part of a pixel in configuration example 5 of an imaging device according to an embodiment. Fig. 14 is a cross-sectional view of a main part of a pixel in configuration example 5 of an imaging device according to an embodiment. Fig. 15 is a cross-sectional view of a main part of a pixel in configuration example 5 of an imaging device according to an embodiment. Fig. 16 is a cross-sectional view of a main part of a pixel in configuration example 6 of an imaging device according to an embodiment. Fig. 17 is a block diagram showing an example of a schematic configuration of a vehicle control system. Fig. 18 is an explanatory diagram showing an example of installation positions of an outside vehicle information detection unit and an imaging unit.

[0009] 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. One embodiment 1.1 Overall configuration 1.2 Example of main configuration 1.3 Effects 2. Example of application to a moving body 3. Other embodiments

[0010] 1. One embodiment> [1.1 Overall configuration] FIG. 1 is a block diagram showing an outline of an imaging device 1 as a light detection device according to one embodiment.

[0011] The photodetector according to one embodiment is a device capable of detecting incident light. The imaging device 1 according to one embodiment has a plurality of pixels P each having a photoelectric conversion unit (photoelectric conversion element) and is configured to photoelectrically convert incident light to generate a signal. The imaging device 1 can receive light that has passed through an optical system (not shown) including an optical lens and generate a signal.

[0012] The imaging device 1 is configured, for example, using a semiconductor substrate (e.g., a silicon substrate) on which a plurality of pixels P are provided. The photoelectric conversion unit of each pixel P of the imaging device 1 is, for example, a photodiode (PD) and is configured to be able to photoelectrically convert light. The imaging device 1 has, as an imaging area, a region (pixel unit 100) in which a plurality of pixels P are two-dimensionally arranged in a matrix. The pixel unit 100 is a pixel array in which a plurality of pixels P are arranged, and can also be called a light-receiving region.

[0013] The imaging device 1 captures incident light (image light) from a subject through an optical system including an optical lens. The imaging device 1 captures an image of the subject formed by the optical lens. The imaging device 1 may perform photoelectric conversion on the received light to generate pixel signals. The imaging device 1 is, for example, a complementary metal oxide semiconductor (CMOS) image sensor. The imaging device 1 can be used in electronic devices such as digital still cameras, video cameras, and mobile phones.

[0014] The imaging device 1 has, for example, a pixel driving unit 111, a signal processing unit 112, a control unit 113, and a processing unit 114 in a peripheral region of the pixel unit 100 (pixel array). The imaging device 1 also has a plurality of control lines Lread and a plurality of signal lines VSL.

[0015] The control lines Lread are signal lines capable of transmitting signals for controlling the pixels P, and are connected to the pixel driving unit 111 and the pixels P of the pixel unit 100. In the example shown in FIG. 1 , in the pixel unit 100, a plurality of control lines Lread are wired for each pixel row made up of a plurality of pixels P arranged in the horizontal direction (row direction). The control lines Lread are configured to transmit control signals for reading out signals from the pixels P.

[0016] The multiple control lines Lread for each pixel row of the imaging device 1 include, for example, wiring for transmitting signals that control transfer transistors, wiring for transmitting signals that control selection transistors, wiring for transmitting signals that control reset transistors, etc. The control lines Lread can also be referred to as drive lines (pixel drive lines) that transmit signals that drive the pixels P.

[0017] The signal line VSL 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 a plurality of signal lines VSL are wired for each pixel column formed by a plurality of pixels P aligned in the vertical direction (column direction).

[0018] The signal line VSL is a vertical signal line configured to transmit signals output from the pixels P. In the imaging device 1, multiple signal lines VSL may be provided for one pixel column. The imaging device 1 may have multiple signal lines VSL for each pixel column.

[0019] The pixel driving unit 111 is configured to be able to drive each pixel P of the pixel unit 100. The pixel driving unit 111 is a driving circuit and is configured by a plurality of circuits including, for example, a buffer, a shift register, an address decoder, etc. The pixel driving unit 111 (pixel driving circuit) generates a signal for driving the pixel P and outputs the signal to each pixel P of the pixel unit 100 via a control line Lread. The pixel driving unit 111 is controlled by the control unit 113 and controls the pixels P of the pixel unit 100.

[0020] The pixel driving unit 111 generates signals for controlling the pixels P, such as signals for controlling the transfer transistors of the pixels P, signals for controlling the selection transistors, and signals for controlling the reset transistors, and supplies these signals to each pixel P via a control line Lread. The pixel driving unit 111 can control the reading of pixel signals from each pixel P. The pixel driving unit 111 can also be referred to as a pixel control unit configured to be able to control each pixel P. The pixel driving unit 111 and the control unit 113 can also be referred to collectively as a pixel control unit.

[0021] The signal processing unit 112 is configured to be able to perform signal processing of the input signal of the pixel P. The signal processing unit 112 is a signal processing circuit and includes, for example, a load circuit unit, an AD conversion unit 40, and a horizontal selection switch. As an example, the load circuit unit is configured by a current source capable of supplying current to the amplification transistor of the pixel P. For example, the load circuit unit forms a source follower circuit together with the amplification transistor of the pixel P. Note that the signal processing unit 112 may also include an amplification circuit unit configured to amplify the signal read out from the pixel P via the signal line VSL.

[0022] The signal processing unit 112 includes a plurality of AD conversion units 40 (AD conversion circuits) and can output pixel signals converted into digital signals by the AD conversion units 40. The AD conversion units 40 are ADCs (Analog to Digital Converters). For example, an AD conversion unit 40 is provided for each of the plurality of signal lines VSL. An AD conversion unit 40 can be provided for each pixel column of the pixel unit 100. The AD conversion units 40 are not limited to SS (single slope) ADCs, and may be ADCs with other configurations.

[0023] The AD conversion unit 40 is configured to convert an input analog signal into a digital signal. The AD conversion unit 40 performs AD conversion processing on the pixel P signal, which is an analog signal input from each pixel P via the signal line VSL. The AD conversion unit 40 (AD conversion circuit) includes, for example, a comparison circuit (comparator circuit) and a counter, and can convert the input pixel P signal into a digital signal with a predetermined number of bits.

[0024] The signals output from each pixel P selected and scanned by the pixel driving unit 111 are input to the signal processing unit 112 via signal lines VSL. The signal processing unit 112 can perform signal processing such as AD conversion of the signals from the pixels P and CDS (Correlated Double Sampling). The signals from each pixel P transmitted through each of the signal lines VSL are subjected to signal processing by the signal processing unit 112 and output to the processing unit 114.

[0025] The processing unit 114 is configured to be able to perform signal processing on the input signal. The processing unit 114 is a processing circuit and is configured, for example, by a circuit that performs various types of signal processing on pixel signals. The processing unit 114 may include a processor and a memory. The processing unit 114 performs signal processing on the signal of pixel P input from the signal processing unit 112 and outputs the processed signal of pixel P. The processing unit 114 can perform various types of signal processing, such as noise reduction processing and gradation correction processing.

[0026] The control unit 113 is configured to be able to control each unit of the 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 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.

[0027] The control unit 113 controls the driving of the pixel driving unit 111, the signal processing unit 112, etc. based on various timing signals (pulse signals, clock signals, etc.) generated by the timing generator. Note that some or all of the signal processing unit 112, the control unit 113, and the processing unit 114 may be configured integrally.

[0028] [1.2 Example of Configuration of Main Parts] A more specific example of the configuration of the imaging device 1 according to one embodiment will now be described.

[0029] 2 is a configuration diagram showing an example of a pixel unit 100 in an image pickup device 1 as a detection device according to an embodiment. FIG. 3 is a circuit diagram showing a circuit configuration of a pixel P in the image pickup device 1 in configuration example 1.

[0030] In the following, as shown in Figure 2, the incident direction of light from the subject 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.

[0031] 3, each pixel P of the imaging device 1 includes a photodiode PD, a transfer transistor TG, a floating diffusion FD, and a readout circuit 20. The photodiode PD is configured to receive light and generate a signal. The photodiode PD is configured to generate electric charges through photoelectric conversion.

[0032] The readout circuit 20 is configured to be able to output a signal based on photoelectrically converted charges. As an example, the readout circuit 20 is provided for a plurality of pixels P. The imaging device 1 has a configuration in which a single readout circuit 20 is shared by a plurality of pixels P.

[0033] 3 , a readout circuit 20 is arranged for every four pixels P (pixels Pa, Pb, Pc, and Pd). Pixels Pa, Pb, Pc, and Pd share one readout circuit 20. For example, 2×2 pixels formed by adjacent pixels P share one readout circuit 20.

[0034] The imaging device 1 can read out pixel signals of each of the 2×2 pixels by operating the readout circuit 20 in a time-division manner. The imaging device 1 can also read out a pixel signal obtained by adding together the signals of each of the 2×2 pixels. Note that the imaging device 1 may have a configuration in which five or more pixels P, for example, eight pixels P, share one readout circuit 20.

[0035] The transfer transistor TG is configured to be able to transfer charges photoelectrically converted by the photodiode PD to the floating diffusion FD. The transfer transistor TG electrically connects or disconnects the photodiode PD and the floating diffusion FD. The transfer transistor TG can transfer charges photoelectrically converted and accumulated by the photodiode PD to the floating diffusion FD.

[0036] 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 photodiode PD. 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.

[0037] 3, the readout circuit 20 includes an amplifier transistor AMP, a select transistor SEL, and a reset transistor RST. The amplifier transistor AMP is configured to generate and output a signal based on the charge accumulated in the floating diffusion FD. The gate of the amplifier transistor AMP is electrically connected to the floating diffusion FD, and receives the voltage converted by the floating diffusion FD.

[0038] The drain of the amplifier transistor AMP is connected to a power supply line to which a power supply voltage VDD is supplied, and the source of the amplifier transistor AMP is connected to a signal line VSL via a selection transistor SEL. The amplifier transistor AMP generates 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 outputs the signal to the signal line VSL. The amplifier transistor AMP is configured to be able to generate a signal based on the charge converted by the photodiode PD.

[0039] The selection transistor SEL is configured to be able to control the output of a signal from the pixel P. The selection transistor SEL is configured to be able to output a signal from the amplification transistor AMP to a signal line VSL. The selection transistor SEL can control the output timing of the signal from the pixel P. The selection transistor SEL is configured to be able to output a signal based on the charge converted by the photodiode PD. The selection transistor SEL may be provided between the power supply line to which the power supply voltage VDD is applied and the amplification transistor AMP. Furthermore, the selection transistor SEL may be omitted as necessary.

[0040] The reset transistor RST is configured to be able to reset the voltage of the floating diffusion FD. The reset 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 reset transistor RST can reset the charge accumulated in the floating diffusion FD and reset the voltage of the floating diffusion FD.

[0041] The transfer transistor TG, the amplification transistor AMP, the selection transistor SEL, and the reset transistor RST may each be a MOS transistor (MOSFET) having a gate, a source, and a drain terminal. In the configuration example of Figure 3, the transfer transistor TG, the amplification transistor AMP, the selection transistor SEL, and the reset transistor RST are each configured as an NMOS transistor. Note that the transfer transistor TG, the amplification transistor AMP, the selection transistor SEL, and the reset transistor RST may also be configured as a PMOS transistor.

[0042] Fig. 4 is a cross-sectional view of a main part of a pixel P in the first configuration example of the imaging device 1. Fig. 5 is a plan view showing an example of the planar configuration of a pixel P in the first configuration example of the imaging device 1.

[0043] 4 , the imaging device 1 according to one embodiment may include a first substrate 101 and a second substrate 102 stacked on the first substrate 101. The first substrate 101 includes a semiconductor layer 110, an insulating layer 211, and a wiring layer 212. The second substrate 102 includes a semiconductor layer 120 and a wiring layer 220.

[0044] The semiconductor layer 120 of the second substrate 102 has a signal processing unit 112 that can perform signal processing on the signal output from the readout circuit 20. The semiconductor layer 120 may also be provided with a pixel driving unit 111, a control unit 113, a processing unit 114, etc. The semiconductor layer 120 may also be provided with other circuits such as a memory, a processor, a power supply circuit, and an interface circuit.

[0045] The imaging device 1 has a configuration in which a semiconductor layer 110, an insulating layer 211, a wiring layer 212, a wiring layer 220, and a semiconductor layer 120 are stacked in the Z-axis direction. From the light incident side, the semiconductor layer 110, the insulating layer 211, the wiring layer 212, the wiring layer 220, and the semiconductor layer 120 are provided.

[0046] The semiconductor layer 110 and the semiconductor layer 120 are made of a semiconductor substrate, for example, a silicon (Si) substrate. The semiconductor layer 110 and the semiconductor layer 120 may be made of a silicon-on-insulator (SOI) substrate, a silicon germanium (SiGe) substrate, or other compound semiconductor materials.

[0047] The insulating films (interlayer insulating films) of the insulating layer 211, the wiring layer 212, and the wiring layer 220 are made of, for example, TEOS, silicon nitride (SiN), silicon oxide (SiO), etc. Also, for example, SiCN, SiCON, HfO ２ , Al ２ O ３ , or ZrO ２ The insulating films of the insulating layer 211, the wiring layer 212, and the wiring layer 220 may be formed using other insulating materials. The insulating films of the insulating layer 211, the wiring layer 212, and the wiring layer 220 also serve as passivation films (protective films) for the thin film transistors, and are formed so as to cover the periphery of each thin film transistor.

[0048] The wiring layer 212 and the wiring layer 220 may be, for example, wiring layers formed by a back end of line (BEOL).

[0049] The wiring layer 212 and the wiring layer 220 include, for example, a conductor film and an insulating film, and have a plurality of wires and vias (VIAs), an interlayer insulating film, etc. The wires of the wiring layer 212 and the wiring layer 220 are formed using, for example, metal materials such as aluminum (Al), copper (Cu), and tungsten (W). The wires of the wiring layer 212 may be composed of other conductive materials. The interlayer insulating film is formed using, for example, silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiON), etc.

[0050] The semiconductor layer 110 of the first substrate 101 includes a photodiode PD as a photoelectric conversion element, a floating diffusion FD, a transfer transistor TG, and an amplification transistor AMP. The semiconductor layer 110 may also include a selection transistor SEL.

[0051] The insulating layer 211 is stacked on the semiconductor layer 110 and has at least one thin film transistor (TFT). The insulating layer 211 further has a wiring 41c that connects the at least one thin film transistor to the semiconductor layer 110. At least a portion of the wiring 41c is made of the same semiconductor material as the at least one thin film transistor. The insulating layer 211 also has a contact portion 51 to the floating diffusion FD and a contact portion 52 to the amplification transistor AMP.

[0052] The contact portion 51 and the contact portion 52 are made of a metal material containing at least one of Au (gold), Pt (platinum), Pd (palladium), copper (Cu), titanium (Ti), tungsten (W), titanium nitride (TiN), tantalum nitride (TaN), titanium aluminum (TiAl), bismuth (Bi), indium (In), aluminum (Al), scandium (Sc), cobalt (Co), molybdenum (Mo), manganese (Mo), etc. The contact portion 51 and the contact portion 52 may also be made of other metal materials.

[0053] The wiring 41c made of a semiconductor material is a local wiring, and is configured to be in direct contact with the contact portion 51 and the contact portion 52.

[0054] In the insulating layer 211, the thin film transistor is provided in the immediate vicinity of the contact portion 51 to the floating diffusion FD. The semiconductor material (channel material) of the thin film transistor in the insulating layer 211 is, for example, an oxide semiconductor (InGaZnO, InZnO, ZnO, SnO, TiO ２The insulating layer 211 may contain at least one material selected from the group consisting of hydrogenated amorphous silicon, low-temperature polysilicon, and the like (single film or laminated film). The semiconductor material of the thin film transistor in the insulating layer 211 may be, for example, a two-dimensional material (MoS ２ , W.S. ２ , MoSe ２ , WSe ２ , HfS ２ The layer may contain at least one material selected from the group consisting of organic semiconductors (fullerene, pentacene, rubrene, etc.), carbon nanotubes, etc. (single film or laminated film).

[0055] The thin film transistor in the insulating layer 211 may be a reset transistor RST. In this case, the reset transistor RST may have a structure in which an electrode 41a serving as a drain electrode, a gate insulating film 41i (gate oxide film), and a gate electrode 41g are stacked on a semiconductor material constituting the wiring 41c in the insulating layer 211.

[0056] The gate insulating film 41i is made of silicon oxide (SiO), silicon nitride (SiN), or Al ２ O ３ , HfO ２ , ZrO ２ , LaO ２ , HfSiO, Y ２ O ３ The gate insulating film 41i may include at least one of the materials of SiO 2 and SiON. The gate insulating film 41i may be made of other insulating materials.

[0057] The electrode 41a serving as a drain electrode may include at least one conductive material selected from the group consisting of copper (Cu), tungsten (W), ruthenium (Ru), and cobalt (Co). The electrode 41a may also be made of other conductive materials. The electrode 41a may be made of a low-resistance conductive material.

[0058] The gate electrode 41g may contain at least one metal material selected from the group consisting of Au, Pt, copper (Cu), Ti, tungsten (W), Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn, etc. The gate electrode 41g may also be made of other metal materials.

[0059] In the imaging device 1 according to Configuration Example 1, the number of manufacturing steps and the area of ​​the transistor can be reduced by using the semiconductor material (channel material) of the thin-film transistor in the insulating layer 211 as the wiring 41c. Also, the thin-film transistor can be formed by adjusting the carrier density to a potential controllable level only directly below the gate electrode 41g.

[0060] (Configuration Example 2) Fig. 6 is a circuit diagram showing a circuit configuration of a pixel P in Configuration Example 2 of an image pickup device 1 according to an embodiment. Fig. 7 is a cross-sectional view of a main part of a pixel P in Configuration Example 2 of an image pickup device 1 according to an embodiment. Fig. 8 is a plan view showing an example of the planar configuration of a pixel P in Configuration Example 2 of an image pickup device 1 according to an embodiment.

[0061] 6, in the image pickup device 1 according to Configuration Example 2, the readout circuit 20 further includes a floating diffusion capacitance switching transistor FDG, as compared to Configuration Example 1. The floating diffusion capacitance switching transistor FDG is provided, for example, between the floating diffusion FD and the reset transistor RST.

[0062] When the floating diffusion capacitance switching transistor FDG is turned on, the capacitance added to the floating diffusion FD of the pixel P increases, making it possible to change the conversion efficiency (gain) when converting charge into voltage. The floating diffusion capacitance switching transistor FDG is a switching transistor that switches the capacitance connected to the gate of the amplification transistor AMP and changes the conversion efficiency.

[0063] In the imaging device 1 according to the second configuration example, as shown in FIG. 7, the reset transistor RST and the floating diffusion capacitance switching transistor FDG are formed in parallel as thin film transistors in the insulating layer 211.

[0064] The floating diffusion capacitance switching transistor FDG may have a structure in which a gate insulating film 42i (gate oxide film) and a gate electrode 42g are stacked on the semiconductor material that constitutes the wiring 41c in the insulating layer 211.

[0065] The gate insulating film 42i is made of silicon oxide (SiO), silicon nitride (SiN), or Al ２ O ３ , HfO ２ , ZrO ２ , LaO ２ , HfSiO, Y ２ O ３ The gate insulating film 42i may include at least one of the materials of SiO 2 and SiON. The gate insulating film 42i may be made of other insulating materials.

[0066] The gate electrode 42g may contain at least one metal material selected from the group consisting of Au, Pt, copper (Cu), Ti, tungsten (W), Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn, etc. The gate electrode 42g may also be made of other metal materials.

[0067] In the image pickup device 1 according to configuration example 2, the reset transistor RST and the floating diffusion capacitance switching transistor FDG are formed in parallel using wiring 41c made of a semiconductor material, which makes it possible to switch the conversion efficiency. In addition, by increasing the area of ​​the floating diffusion capacitance switching transistor FDG and using it as a capacitive element, it is possible to ensure a sufficient dynamic range.

[0068] The other configurations may be substantially the same as those in the first configuration example.

[0069] 9 is a circuit diagram showing a circuit configuration of a pixel P in a configuration example 3 of an imaging device 1 according to an embodiment. FIG. 10 is a cross-sectional view of a main part of a pixel P in a configuration example 3 of an imaging device 1 according to an embodiment.

[0070] In the imaging device 1 according to Configuration Example 3, the readout circuit 20 further includes a capacitance element C1 in addition to the components of Configuration Example 2. One end of the capacitance element C1 is connected between the floating diffusion FD and the floating diffusion capacitance switching transistor FDG.

[0071] The other configurations may be substantially the same as those in the second configuration example.

[0072] 11 is a circuit diagram showing a circuit configuration of a pixel P in configuration example 4 of an image pickup device 1 according to an embodiment. Fig. 12 is a plan view showing an example of the planar configuration of a pixel P in configuration example 4 of an image pickup device 1 according to an embodiment.

[0073] In the imaging device 1 according to Configuration Example 4, compared to Configuration Example 2, a floating diffusion capacitance switching transistor FDG is provided between adjacent pixel groups. In the example shown in FIGS. 11 and 12 , four pixels Pa, Pb, Pc, and Pd form one pixel group. Each pixel group shares one readout circuit 20. The floating diffusion capacitance switching transistor FDG and each pixel group are connected in the insulating layer 211 by wiring 41c made of a semiconductor material.

[0074] In the imaging device 1 according to configuration example 4, the floating diffusion capacitance switching transistor FDG is provided between adjacent pixel groups using wiring 41c made of a conductive material, which makes it possible to connect the adjacent pixel groups at a minimum distance while switching the conversion efficiency. Note that by forming two floating diffusion capacitance switching transistors FDG, it is also possible to quantify each pixel group.

[0075] The other configurations may be substantially the same as those in the second configuration example.

[0076] Configuration Example 5 FIGS. 13 to 15 are cross-sectional views of a main part of a pixel P in Configuration Example 5 of an imaging device 1 according to an embodiment.

[0077] 13 , in the imaging device 1 according to Configuration Example 5, in comparison with Configuration Example 1, the semiconductor material constituting the wiring 41c in the insulating layer 211 extends to the semiconductor layer 110, thereby forming a contact portion 51c to the floating diffusion FD. In addition, the semiconductor material constituting the wiring 41c extends to the semiconductor layer 110, thereby forming a contact portion 52c to the amplifier transistor AMP. The contact portion 52c extends so as to be connected to the gate electrode of the amplifier transistor AMP.

[0078] Similarly, in the imaging device 1 according to Configuration Example 5, even for Configuration Example 2 described above in which the floating diffusion capacitance switching transistor FDG is provided, the contact portion 51c may be formed by extending the semiconductor material of the wiring 41c to the floating diffusion FD, as shown in Fig. 14. Similarly, the contact portion 52c may be formed by extending the semiconductor material of the wiring 41c to the gate electrode of the amplification transistor AMP.

[0079] 15, a metal film 51a may be formed at least between the floating diffusion FD and the semiconductor material that constitutes the contact portion 51c to the floating diffusion FD. The metal film 51a may contain at least one metal material selected from the group consisting of Ti, TiN, Ta, TaN, and W. The formation of the metal film 51a reduces the contact resistance with the semiconductor material, and reduces deterioration of charge transfer in the floating diffusion FD.

[0080] The other configurations may be substantially the same as those in the above-described configuration example 1 or 2.

[0081] Configuration Example 6 FIG. 16 is a cross-sectional view of a main part of a pixel P in a configuration example 6 of an imaging device 1 according to an embodiment.

[0082] In the imaging device 1 according to Configuration Example 6, the semiconductor layer 110 further includes a diffusion layer 61 in comparison with Configuration Example 5. In addition, in the insulating layer 211, the semiconductor material constituting the wiring 41c is formed in a first region in which the reset transistor RST (and the floating diffusion capacitance switching transistor FDG) are formed, and a second region different from the first region.

[0083] In the insulating layer 211, the semiconductor material formed in the second region is extended so as to be connected to the diffusion layer 61 provided in the semiconductor layer 110. As a result, the protection diode 60 is formed by the diffusion layer 61 and the semiconductor material connected to the diffusion layer 61. For example, if the diffusion layer 61 is a p-type diffusion layer and the semiconductor material forming the wiring 41c is an n-type, a PN junction diode can be formed as the protection diode 60.

[0084] The first region and the second region may be connected by a copper (Cu) wiring 63. For example, the gate electrode 41g of the reset transistor RST may be connected to the wiring 41c in the second region by the wiring 63.

[0085] The other configurations may be substantially the same as those in the fifth configuration example.

[0086] (Modification) In each of the above configuration examples, a selection transistor SEL using the wiring 41c as a semiconductor material may be further provided in the insulating layer 211.

[0087] [1.3 Effects] As described above, in the imaging device 1 as a detection device according to one embodiment, the insulating layer 211 has a thin-film transistor and wiring 41 c, and at least a portion of the wiring 41 c is made of the same semiconductor material as the thin-film transistor. This makes it possible to provide a photodetection device that can reduce random noise and optimize the layout of the transistors on the semiconductor substrate (semiconductor layer 110).

[0088] According to the imaging device 1 as a detection device of one embodiment, the use of local wiring using wiring 41c made of semiconductor material can improve conversion efficiency and reduce random noise. By forming thin-film transistors using wiring 41c made of semiconductor material in the insulating layer 211 on the semiconductor substrate, substrate capacitance and diffusion layer capacitance can be eliminated, allowing elements to be formed using the shortest route. Furthermore, capacitance such as through-vias in two-stage pixels can be eliminated. It is possible to reduce the number of transistors formed on the semiconductor substrate, enabling transistor size expansion, Qs increase, and layout optimization for amplifier transistors AMP and the like.

[0089] The effects described in this specification are merely examples and are not limiting, and other effects may also be achieved. The same applies to the effects of other embodiments described below.

[0090] 2. 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.

[0091] FIG. 17 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.

[0092] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 17, 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the distance between vehicles, maintaining vehicle speed, vehicle collision warning, vehicle lane departure warning, etc.

[0099] 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.

[0100] 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.

[0101] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying the passengers of the vehicle or the outside of the vehicle of information. In the example of Fig. 17, 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.

[0102] FIG. 18 is a diagram showing an example of the installation position of the imaging unit 12031.

[0103] In FIG. 18, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0104] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided on the top of the windshield inside the vehicle cabin is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0105] 18 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] The above describes an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the imaging unit 12031, the driver state detection unit 12041, and the imaging units 12101, 12102, 12103, 12104, and 12105 among the above-described configurations.

[0111] 3. Other Embodiments The technology according to the present disclosure is not limited to the description of the above embodiment, and various modifications are possible.

[0112] For example, the present technology can be configured as follows: According to the present technology configured as follows, an insulating layer has thin-film transistors and wiring, and at least a portion of the wiring is made of the same semiconductor material as the thin-film transistors. This makes it possible to provide a photodetector that can reduce random noise and optimize the layout of transistors on a semiconductor substrate.

[0113] (1) A photodetector comprising: a semiconductor substrate having a photoelectric conversion element that converts light into electricity; and an insulating layer laminated on the semiconductor substrate and having at least one thin film transistor, wherein the insulating layer further has wiring connecting the thin film transistor to the semiconductor substrate, and at least a portion of the wiring is made of the same semiconductor material as the thin film transistor. (2) The photodetector according to (1), wherein the semiconductor substrate further has at least one of a floating diffusion capacitance, a transfer transistor, and an amplification transistor. (3) The photodetector according to (2), wherein the thin film transistor includes at least one of a reset transistor, a floating diffusion capacitance switching transistor, and a selection transistor. (4) The photodetector according to (3), wherein the insulating layer further has a contact portion to the floating diffusion capacitance, and the thin film transistor is provided immediately adjacent to the contact portion. (5) The photodetector according to (4), wherein the contact portion is made of a metal material containing at least one of Au, Pt, Cu, Ti, W, Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn. (6) The photodetector according to (5), wherein the wiring made of the semiconductor material and the contact portion made of the metal material are configured to be in direct contact with each other. (7) The photodetector according to (4), wherein the contact portion is formed by extending the semiconductor material constituting the wiring in the insulating layer to the semiconductor substrate. (8) The photodetector according to (7), wherein the semiconductor material constituting the wiring is extended in the insulating layer so as to be connected to at least one of the floating diffusion capacitance and the gate electrode of the amplification transistor provided on the semiconductor substrate. (9) The photodetector according to (8), wherein at least one of the reset transistor and the floating diffusion capacitance switching transistor has a structure in which a drain electrode, a gate insulating film, and a gate electrode are stacked on the semiconductor material constituting the wiring in the insulating layer.(10) The photodetector according to (9) above, wherein the semiconductor substrate further has a diffusion layer, and the semiconductor material constituting the wiring in the insulating layer is formed in a first region where the reset transistor and the floating diffusion capacitance switching transistor are formed, and a second region different from the first region, and the semiconductor material formed in the second region of the insulating layer is extended to connect to the diffusion layer provided in the semiconductor substrate, thereby forming a diode by the diffusion layer and the semiconductor material connected to the diffusion layer. (11) The photodetector according to any one of (7) to (10) above, wherein a metal film is formed at least between the semiconductor material constituting the contact portion to the floating diffusion capacitance and the floating diffusion capacitance. (12) The photodetector according to (11) above, wherein the metal film includes at least one metal material selected from the group consisting of Ti, TiN, Ta, TaN, and W. (13) The photodetector device according to any one of (1) to (12), wherein the semiconductor material of the thin film transistor includes at least one material selected from the group consisting of an oxide semiconductor, hydrogenated amorphous silicon, and low-temperature polysilicon. (14) The thin film transistor is made of silicon oxide, silicon nitride, or Al. ２ O ３ , HfO ２ , ZrO ２ , LaO ２ , HfSiO, Y ２ O ３ and SiON; and a gate electrode containing at least one metal material selected from the group consisting of Au, Pt, Cu, Ti, W, Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn.

[0114] This application claims priority based on Japanese Patent Application No. 2023-212394, filed on December 15, 2023, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0115] 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 photodetector comprising: a semiconductor substrate having a photoelectric conversion element that converts light into electricity; and an insulating layer laminated on the semiconductor substrate and having at least one thin film transistor, the insulating layer further having wiring connecting the thin film transistor to the semiconductor substrate, at least a portion of the wiring being made of the same material as the semiconductor material of the thin film transistor.

2. The photodetector device according to claim 1, wherein the semiconductor substrate further comprises at least one of a floating diffusion capacitance, a transfer transistor, and an amplifying transistor.

3. The photodetector device according to claim 2, wherein the thin-film transistor includes at least one of a reset transistor, a floating diffusion capacitance switching transistor, and a selection transistor.

4. The photodetector according to claim 3, wherein the insulating layer further has a contact portion to the floating diffusion capacitance, and the thin film transistor is provided in close proximity to the contact portion.

5. The photodetector according to claim 4, wherein the contact portion is made of a metal material containing at least one of Au, Pt, Cu, Ti, W, Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn.

6. The photodetector according to claim 5, wherein the wiring made of the semiconductor material and the contact portion made of the metal material are configured to be in direct contact with each other.

7. The photodetector according to claim 4, wherein the contact portion is formed by extending the semiconductor material constituting the wiring in the insulating layer to the semiconductor substrate.

8. The photodetector according to claim 7, wherein the semiconductor material constituting the wiring is extended in the insulating layer so as to be connected to at least one of the floating diffusion capacitance and the gate electrode of the amplifying transistor provided in the semiconductor substrate.

9. The photodetector according to claim 8, wherein at least one of the reset transistor and the floating diffusion capacitance switching transistor has a structure in which a drain electrode, a gate insulating film and a gate electrode are stacked on the semiconductor material constituting the wiring in the insulating layer.

10. The photodetector according to claim 9, wherein the semiconductor substrate further has a diffusion layer, and in the insulating layer, the semiconductor material constituting the wiring is formed in a first region in which the reset transistor and the floating diffusion capacitance switching transistor are formed, and a second region different from the first region, and in the insulating layer, the semiconductor material formed in the second region is extended so as to be connected to the diffusion layer provided in the semiconductor substrate, thereby forming a diode by the diffusion layer and the semiconductor material connected to the diffusion layer.

11. The photodetector according to claim 7, further comprising a metal film formed at least between said semiconductor material constituting said contact portion to said floating diffusion capacitance and said floating diffusion capacitance.

12. The photodetector according to claim 11, wherein the metal film contains at least one metal material selected from the group consisting of Ti, TiN, Ta, TaN, and W.

13. The photodetector device according to claim 1, wherein the semiconductor material of the thin film transistor includes at least one of an oxide semiconductor, hydrogenated amorphous silicon, and low-temperature polysilicon.

14. The thin film transistor is made of silicon oxide, silicon nitride, Al ２ O ３ , HfO ２ , ZrO ２ , LaO ２ , HfSiO, Y ２ O ３ 2. The photodetector according to claim 1 , further comprising: a gate insulating film including at least one of the following materials: TiN, TiAl, Bi, In, Al, Sc, Co, and SiON; and a gate electrode including at least one of the following metal materials: Au, Pt, Cu, Ti, W, Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn.

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