light detection device

Abstract

The light detection device of the present disclosure comprises a semiconductor substrate having a photoelectric conversion element that converts light into a photoelectric element, and an insulating layer stacked on the semiconductor substrate and having at least one thin-film transistor, wherein the insulating layer further has wiring connecting the thin-film transistor and the semiconductor substrate, and at least a portion of the wiring is composed of the same material as the semiconductor material of the thin-film transistor.

Description

Technology Field

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

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

[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. Because of this, the capacitance of the diffusion layer on the semiconductor substrate is large. In addition, there are layout constraints on the semiconductor substrate in the case of micropixels or pixel sharing structures.

[0005] For this reason, it is desirable to provide a photodetector capable of optimizing the layout of transistors on a semiconductor substrate while reducing random noise.

[0006] A light detection device according to one embodiment of the present disclosure comprises a semiconductor substrate having a photoelectric conversion element that converts light into a photoelectric element, and an insulating layer stacked on the semiconductor substrate and having at least one thin-film transistor, wherein the insulating layer further has a wiring connecting the thin-film transistor and the semiconductor substrate, and at least a portion of the wiring is composed of the same material as the semiconductor material of the thin-film transistor.

[0007] In a light detection device according to one embodiment of the present disclosure, the insulating layer has a thin-film transistor and wiring, and at least a portion of the wiring is composed of the same material as the semiconductor material of the thin-film transistor. Brief explanation of the drawing

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

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, the description will be carried out in the following order.

[0010] 1. One implementation form

[0011] 1.1 Overall Structure

[0012] 1.2 Example of Main Part Composition

[0013] 1.3 Effect

[0014] 2. Application examples for moving objects

[0015] 3. Other embodiments

[0016] <1. Implementation form>

[0017] [1.1 Overall Structure]

[0018] FIG. 1 is a block diagram showing an overview of an imaging device (1) as a light detection device according to one embodiment.

[0019] A light detection device according to one embodiment is a device capable of detecting incident light. An imaging device (1) according to one embodiment has a plurality of pixels (P) having a photoelectric conversion unit (photoelectric conversion element) and is configured to generate a signal by photoelectrically converting incident light. The imaging device (1) can generate a signal by receiving light that has passed through an optical system (not shown) including an optical lens.

[0020] The imaging device (1) is configured using, for example, a semiconductor substrate (e.g., a silicon substrate) having a plurality of pixels (P). The photoelectric conversion unit of each pixel (P) of the imaging device (1) is, for example, a photodiode (PD) and is configured to convert light into photoelectric. The imaging device (1) has an area (pixel section (100)) in which a plurality of pixels (P) are arranged in a matrix form in two dimensions as an imaging area. The pixel section (100) is a pixel array in which a plurality of pixels (P) are arranged, and can also be called a light receiving area.

[0021] An imaging device (1) receives 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) can generate a pixel signal by converting the received light into photoelectric power. The imaging device (1) is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The imaging device (1) can be used in electronic devices such as, for example, digital still cameras, video cameras, and mobile phones.

[0022] 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 the peripheral area of ​​the pixel unit (100) (pixel array). In addition, the imaging device (1) is provided with a plurality of control lines (Lread) and a plurality of signal lines (VSL).

[0023] A control line (Lread) is a signal line capable of transmitting a signal to control a pixel (P) and is connected to a pixel driving unit (111) and a pixel (P) of a pixel unit (100). In the example illustrated in FIG. 1, in the pixel unit (100), a plurality of control lines (Lread) are wired for each pixel row composed of a plurality of pixels (P) arranged in a horizontal direction (row direction). The control line (Lread) is configured to transmit a control signal for reading a signal from a pixel (P).

[0024] A plurality of control lines (Lread) for each pixel row of the imaging device (1) include, for example, wiring that transmits a signal to control a transmission transistor, wiring that transmits a signal to control a selection transistor, and wiring that transmits a signal to control a reset transistor. A control line (Lread) can also be called a driving line (pixel driving line) that transmits a signal to drive a pixel (P).

[0025] A signal line (VSL) is a signal line capable of transmitting a signal from a pixel (P) and is connected to a pixel (P) of a pixel unit (100) and a signal processing unit (112). In the pixel unit (100), for example, one or more signal lines (VSL) are wired for each pixel row composed of multiple pixels (P) arranged in a vertical direction (column direction).

[0026] The signal line (VSL) is a vertical signal line and is configured to transmit a signal output from a pixel (P). In the imaging device (1), multiple signal lines (VSL) may be provided for one pixel row. The imaging device (1) may have multiple signal lines (VSL) for each pixel row.

[0027] The pixel driving unit (111) is configured to drive each pixel (P) of the pixel unit (100). The pixel driving unit (111) is a driving circuit and is composed of a plurality of circuits including, for example, a buffer, a shift register, and an address decoder. The pixel driving unit (111) (pixel driving circuit) generates a signal to drive the pixel (P) and outputs it to each pixel (P) of the pixel unit (100) through a control line (Lread). The pixel driving unit (111) is controlled by the control unit (113) to control the pixel (P) of the pixel unit (100).

[0028] The pixel driving unit (111) generates signals for controlling a pixel (P), such as a signal for controlling a transmission transistor of a pixel (P), a signal for controlling a selection transistor, and a signal for controlling a reset transistor, and supplies them to each pixel (P) via a control line (Lread). The pixel driving unit (111) can perform control to read pixel signals from each pixel (P). The pixel driving unit (111) can also be described as a pixel control unit configured to control each pixel (P). Additionally, the pixel driving unit (111) and the control unit (113) can be combined and referred to as a pixel control unit.

[0029] The signal processing unit (112) is configured to perform signal processing of the input signal of the pixel (P). The signal processing unit (112) is a signal processing circuit and, for example, has a load circuit unit, an AD converter unit (40), and a horizontal selection switch. The load circuit unit is, for example, configured by a current source capable of supplying current to the amplification transistor of the pixel (P). The load circuit unit forms a source follower circuit together with the amplification transistor of the pixel (P), for example. Additionally, the signal processing unit (112) may have an amplification circuit unit configured to amplify the signal read from the pixel (P) through the signal line (VSL).

[0030] The signal processing unit (112) includes a plurality of AD converters (40) (AD converter circuits) and can output a pixel signal converted into a digital signal by the AD converters (40). The AD converters (40) are Analog to Digital Converters (ADCs). The AD converters (40) are provided for each of the plurality of signal lines (VSLs), for example. An AD converter (40) may be provided for each pixel row of the pixel unit (100). The AD converters (40) are not limited to SS (Single Slope) type ADCs and may be ADCs of other configurations.

[0031] The AD converter (40) is configured to convert an input analog signal into a digital signal. The AD converter (40) performs AD conversion processing on the signal of a pixel (P), which is an analog signal input from each pixel (P) through a signal line (VSL). The AD converter (40) (AD conversion circuit) includes, for example, a comparison circuit (comparator circuit) and a counter, and can convert the input signal of a pixel (P) into a digital signal with a predetermined number of bits.

[0032] The signal output from each pixel (P) selected and scanned by the pixel driving unit (111) is input to the signal processing unit (112) through the signal line (VSL). The signal processing unit (112) can perform signal processing, such as AD conversion of the signal of the pixel (P) or CDS (Correlated Double Sampling). The signal of each pixel (P) transmitted through each of the signal lines (VSL) is processed by the signal processing unit (112) and output to the processing unit (114).

[0033] The processing unit (114) is configured to perform signal processing on an input signal. The processing unit (114) is a processing circuit and is configured, for example, by a circuit that performs various signal processing on a pixel signal. The processing unit (114) may include a processor and a memory. The processing unit (114) performs signal processing on a signal of a pixel (P) input from the signal processing unit (112) and outputs the signal of the pixel (P) after processing. The processing unit (114) can perform various signal processing, for example, noise reduction processing and grayscale correction processing.

[0034] The control unit (113) is configured to control each part of the imaging device (1). The control unit (113) receives data such as a clock and an operation mode commanded from the outside, and can also output data such as internal information of the imaging device (1). The control unit (113) is a control circuit and, for example, has a timing generator configured to generate various timing signals.

[0035] The control unit (113) controls the driving of the pixel driving unit (111) and the signal processing unit (112), etc., based on various timing signals (pulse signals, clock signals, etc.) generated by the timing generator. In addition, some or all of the signal processing unit (112), the control unit (113), and the processing unit (114) may be integrally formed.

[0036] [1.2 Example of Main Section Composition]

[0037] Hereinafter, a more specific configuration example of the imaging device (1) according to one embodiment will be described.

[0038] (Composition Example 1)

[0039] FIG. 2 is a configuration diagram illustrating an example of a pixel portion (100) in an imaging device (1) as a detection device according to one embodiment. FIG. 3 is a circuit diagram illustrating the circuit configuration of a pixel (P) in configuration example 1 of the imaging device (1).

[0040] In the following, as shown in FIG. 2, the incident direction of light from the subject is the Z-axis direction, the left-right direction of the ground perpendicular to the Z-axis direction is the X-axis direction, and the up-down direction of the ground perpendicular to the Z-axis direction and the X-axis direction is the Y-axis direction.

[0041] As shown in FIG. 3, the pixel (P) of the imaging device (1) has 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 an electric charge by photoelectric conversion.

[0042] The reading circuit (20) is configured to output a signal based on photoelectrically converted charge. As an example, the reading circuit (20) is provided for a plurality of pixels (P). The imaging device (1) has a configuration in which a plurality of pixels (P) share one reading circuit (20).

[0043] In the example illustrated in FIG. 3, a read circuit (20) is provided for every four pixels (P) (pixels (Pa, Pb, Pc, Pd)). Pixels (Pa), pixel (Pb), pixel (Pc), and pixel (Pd) share one read circuit (20). For example, a 2×2 pixel composed of adjacent pixels (P) shares one read circuit (20).

[0044] The imaging device (1) can read each pixel signal of a 2×2 pixel by operating the reading circuit (20) in a time-division manner. Additionally, the imaging device (1) can also read a pixel signal in which each signal of a 2×2 pixel is added. Additionally, the imaging device (1) may have a configuration in which five or more pixels (P), for example, eight pixels (P), share one reading circuit (20).

[0045] The transfer transistor (TG) is configured to transfer the charge converted by photoelectricity 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 the charge accumulated by photoelectric conversion by the photodiode (PD) to the floating diffusion (FD).

[0046] The floating diffusion (FD) is an accumulation unit configured to accumulate transferred charges. The floating diffusion (FD) can accumulate charges converted by photoelectricity using a photodiode (PD). The floating diffusion (FD) can also be described as a retention unit capable of holding transferred charges. The floating diffusion (FD) accumulates transferred charges and converts them into a voltage according to the capacitance of the floating diffusion (FD).

[0047] The reading circuit (20) has an amplification transistor (AMP), a selection transistor (SEL), and a reset transistor (RST), as shown in FIG. 3, for example. The amplification transistor (AMP) is configured to generate and output a signal based on the charge accumulated in the floating diffusion (FD). The gate of the amplification transistor (AMP) is electrically connected to the floating diffusion (FD) so that the voltage converted by the floating diffusion (FD) is input.

[0048] The drain of the amplifier transistor (AMP) is connected to a power line to which the power supply voltage (VDD) is supplied, and the source of the amplifier transistor (AMP) is connected to a signal line (VSL) through a selector transistor (SEL). The amplifier transistor (AMP) can generate a signal based on the charge accumulated in the floating diffusion (FD), that is, a signal based on the voltage of the floating diffusion (FD), and output it to the signal line (VSL). The amplifier transistor (AMP) is configured to generate a signal based on the charge converted by the photodiode (PD).

[0049] The select transistor (SEL) is configured to control the output of the pixel (P) signal. The select transistor (SEL) is configured to output a signal from the amplifier transistor (AMP) to the signal line (VSL). The select transistor (SEL) can control the output timing of the pixel (P) signal. The select transistor (SEL) is configured to output a signal based on the charge converted by the photodiode (PD). Additionally, the select transistor (SEL) may be placed between the power line to which the power supply voltage (VDD) is applied and the amplifier transistor (AMP). Furthermore, the select transistor (SEL) may be omitted if necessary.

[0050] The reset transistor (RST) is configured to reset the voltage of the floating diffusion (FD). The reset transistor (RST) is electrically connected to a power line to which the 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).

[0051] The transfer transistor (TG), amplifier transistor (AMP), select transistor (SEL), and reset transistor (RST) may each be a MOS transistor (MOSFET) having gate, source, and drain terminals. In the configuration example of FIG. 3, the transfer transistor (TG), amplifier transistor (AMP), select transistor (SEL), and reset transistor (RST) are each configured by NMOS transistors. Additionally, the transfer transistor (TG), amplifier transistor (AMP), select transistor (SEL), and reset transistor (RST) may be configured by PMOS transistors.

[0052] FIG. 4 is a cross-sectional view of the main part of a pixel (P) in configuration example 1 of an imaging device (1). FIG. 5 is a plan view illustrating an example of the planar configuration of a pixel (P) in configuration example 1 of an imaging device (1).

[0053] An imaging device (1) according to one embodiment may have a first substrate (101) and a second substrate (102) laminated on the first substrate (101), as shown in FIG. 4. The first substrate (101) has a semiconductor layer (110), an insulating layer (211), and a wiring layer (212). The second substrate (102) has a semiconductor layer (120) and a wiring layer (220).

[0054] The semiconductor layer (120) of the second substrate (102) has a signal processing unit (112) capable of performing signal processing on a signal output from a reading circuit (20). Additionally, the semiconductor layer (120) may be provided with a pixel driving unit (111), a control unit (113), and a processing unit (114), etc. Other circuits, such as a memory, a processor, a power circuit, and an interface circuit, may be provided in the semiconductor layer (120).

[0055] 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 side where light is incident, the semiconductor layer (110), the insulating layer (211), the wiring layer (212), the wiring layer (220), and the semiconductor layer (120) are provided.

[0056] The semiconductor layer (110) and the semiconductor layer (120) are formed by a semiconductor substrate, for example, a Si (silicon) substrate. Additionally, the semiconductor layer (110) and the semiconductor layer (120) may be formed using an SOI (Silicon On Insulator) substrate, a SiGe (silicon germanium) substrate, or other compound semiconductor materials.

[0057] The insulating layer (211), the wiring layer (212), and the insulating film (interlayer insulating film) of the wiring layer (220) are composed using, for example, TEOS, silicon nitride (SiN), silicon oxide (SiO), etc. Additionally, they may be formed using, for example, SiCN, SiCON, HfO2, Al2O3, or ZrO2, etc. Furthermore, the insulating film of the insulating layer (211), the wiring layer (212), and the wiring layer (220) may be composed using other insulating materials. The insulating film of the insulating layer (211), the wiring layer (212), and the wiring layer (220) also serves as a passivation film (protective film) for the thin-film transistor and is formed to cover the area around each thin-film transistor.

[0058] The wiring layer (212) and the wiring layer (220) may be, for example, a wiring layer formed by BEOL (Back End of Line).

[0059] The wiring layer (212) and the wiring layer (220) include, for example, a conductive film and an insulating film, and have a plurality of wirings, vias (VIA), interlayer insulating films, etc. The wiring of the wiring layer (212) and the wiring layer (220) is formed using, for example, a metal material such as aluminum (Al), copper (Cu), and tungsten (W). The wiring of the wiring layer (212) may be formed using other conductive materials. The interlayer insulating film is formed using, for example, silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiON), etc.

[0060] The semiconductor layer (110) of the first substrate (101) has a photodiode (PD) as a photoelectric conversion element, a floating diffusion (FD), a transfer transistor (TG), and an amplification transistor (AMP). Additionally, the semiconductor layer (110) may have a selection transistor (SEL).

[0061] The insulating layer (211) is laminated onto the semiconductor layer (110) and has at least one thin film transistor (TFT). The insulating layer (211) further has a wiring (41c) connecting the at least one thin film transistor to the semiconductor layer (110). At least a portion of the wiring (41c) is composed of the same material as the semiconductor material of the at least one thin film transistor. Additionally, the insulating layer (211) further has a contact portion (51) to a floating diffusion (FD) and a contact portion (52) to an amplifier transistor (AMP).

[0062] The contact portion (51) and the contact portion (52) are composed of a metal material including 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), and manganese (Mn). Additionally, the contact portion (51) and the contact portion (52) may be composed using other metal materials.

[0063] The wiring (41c) composed of semiconductor material is local wiring. The wiring (41c) is configured to make direct contact with the contact portion (51) and the contact portion (52).

[0064] 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) may include, for example, at least one material selected from oxide semiconductors (InGaZnO, InZnO, ZnO, SnO, TiO2, etc.), hydride amorphous silicon, and low-temperature polysilicon (single film or stacked film). Additionally, the semiconductor material of the thin-film transistor in the insulating layer (211) may include, for example, at least one material selected from two-dimensional materials (MoS2, WS2, MoSe2, WSe2, HfS2, etc.), organic semiconductors (fullerene, pentacene, rubrene, etc.), and carbon nanotubes (single film or stacked film).

[0065] 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) 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).

[0066] The gate insulating film (41i) may include at least one material among silicon oxide (SiO), silicon nitride (SiN), Al2O3, HfO2, ZrO2, LaO2, HfSiO, Y2O3, and SiON. Additionally, the gate insulating film (41i) may be composed of other insulating materials.

[0067] The electrode (41a) as a drain electrode may include at least one conductive material among, for example, copper (Cu), tungsten (W), ruthenium (Ru), cobalt (Co), etc. Additionally, the electrode (41a) may be constructed using other conductive materials. The electrode (41a) may be constructed from a low-resistance conductive material.

[0068] The gate electrode (41g) may include at least one metal material among Au, Pt, copper (Cu), Ti, tungsten (W), Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn. Additionally, the gate electrode (41g) may be constructed using other metal materials.

[0069] In the imaging device (1) according to Configuration Example 1, by using the semiconductor material (channel material) of the thin-film transistor in the insulating layer (211) as wiring (41c), the number of manufacturing processes and the area of ​​the transistor can be reduced. In addition, the thin-film transistor can be formed by adjusting the carrier density to a potential controllable only directly below the gate electrode (41g).

[0070] (Composition Example 2)

[0071] FIG. 6 is a circuit diagram illustrating the circuit configuration of a pixel (P) in configuration example 2 of an imaging device (1) according to one embodiment. FIG. 7 is a cross-sectional view of the main part of a pixel (P) in configuration example 2 of an imaging device (1) according to one embodiment. FIG. 8 is a plan view illustrating an example of the planar configuration of a pixel (P) in configuration example 2 of an imaging device (1) according to one embodiment.

[0072] The imaging device (1) according to Configuration Example 2, compared to Configuration Example 1, has a reading circuit (20) that further includes a floating diffusion capacitance switching transistor (FDG) as shown in FIG. 6. The floating diffusion capacitance switching transistor (FDG) is provided, for example, between a floating diffusion (FD) and a reset transistor (RST).

[0073] By turning on the floating diffusion capacitance switching transistor (FDG), 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 changes the conversion efficiency by switching the capacitance connected to the gate of the amplifier transistor (AMP).

[0074] In the imaging device (1) according to Configuration Example 2, as shown in FIG. 7, a reset transistor (RST) and a floating diffusion capacitance switching transistor (FDG) are formed in parallel as thin-film transistors in an insulating layer (211).

[0075] 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 a semiconductor material constituting wiring (41c) in an insulating layer (211).

[0076] The gate insulating film (42i) may include at least one material among silicon oxide (SiO), silicon nitride (SiN), Al2O3, HfO2, ZrO2, LaO2, HfSiO, Y2O3, and SiON. Additionally, the gate insulating film (42i) may be composed of other insulating materials.

[0077] The gate electrode (42g) may include at least one metal material among Au, Pt, copper (Cu), Ti, tungsten (W), Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn. Additionally, the gate electrode (42g) may be constructed using other metal materials.

[0078] In the imaging 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 semiconductor material, thereby enabling switching of conversion efficiency. Additionally, by increasing the area of ​​the floating diffusion capacitance switching transistor (FDG) and using it as a capacitive element, it is also possible to secure a dynamic range.

[0079] Other configurations may be nearly identical to Configuration Example 1 above.

[0080] (Composition Example 3)

[0081] FIG. 9 is a circuit diagram illustrating the circuit configuration of a pixel (P) in configuration example 3 of an imaging device (1) according to one embodiment. FIG. 10 is a cross-sectional view of the main part of a pixel (P) in configuration example 3 of an imaging device (1) according to one embodiment.

[0082] The imaging device (1) according to Configuration Example 3 has, compared to Configuration Example 2, a reading circuit (20) further includes a capacitance element (C1). One end of the capacitance element (C1) is connected between a floating diffusion (FD) and a floating diffusion capacitance switching transistor (FDG).

[0083] Other configurations may be approximately the same as Configuration Example 2 above.

[0084] (Composition Example 4)

[0085] FIG. 11 is a circuit diagram illustrating the circuit configuration of a pixel (P) in configuration example 4 of an imaging device (1) according to one embodiment. FIG. 12 is a plan view illustrating an example of the planar configuration of a pixel (P) in configuration example 4 of an imaging device (1) according to one embodiment.

[0086] The imaging device (1) according to Configuration Example 4, compared to Configuration Example 2, has floating diffusion capacitance switching transistors (FDG) arranged between adjacent pixel groups. In the example shown in FIGS. 11 and 12, four pixels (Pa, Pb, Pc, Pd) are made into one pixel group. Each pixel group shares one readout circuit (20). The floating diffusion capacitance switching transistors (FDG) and each pixel group are connected by wiring (41c) made of semiconductor material in an insulating layer (211).

[0087] In the imaging device (1) according to Configuration Example 4, by using wiring (41c) made of semiconductor material to arrange floating diffusion capacitance switching transistors (FDG) between adjacent pixel groups, it is possible to switch conversion efficiency while connecting adjacent pixel groups at a minimum distance. In addition, by forming two floating diffusion capacitance switching transistors (FDG), it is also possible to quantify each pixel group.

[0088] Other configurations may be nearly identical to Configuration Example 2 above.

[0089] (Composition Example 5)

[0090] FIGS. 13 to 15 are cross-sectional views of the main part of a pixel (P) in configuration example 5 of an imaging device (1) according to one embodiment.

[0091] In the imaging device (1) according to Configuration Example 5, compared to Configuration Example 1, as shown in FIG. 13, a semiconductor material constituting the wiring (41c) in the insulating layer (211) is extended to the semiconductor layer (110) to form a contact portion (51c) to the floating diffusion (FD). Additionally, a semiconductor material constituting the wiring (41c) is extended to the semiconductor layer (110) to form a contact portion (52c) to the amplification transistor (AMP). The contact portion (52c) is extended to be connected to the gate electrode of the amplification transistor (AMP).

[0092] In addition, the imaging device (1) according to Configuration Example 5 may have a contact portion (51c) formed by extending the semiconductor material constituting the wiring (41c) to the floating diffusion (FD), as shown in FIG. 14, in the same manner as Configuration Example 2 in which a floating diffusion capacitance switching transistor (FDG) is provided. Likewise, the contact portion (52c) may be formed by extending the semiconductor material constituting the wiring (41c) to the gate electrode of the amplification transistor (AMP).

[0093] Additionally, as shown in FIG. 15, at least a metal film (51a) may be formed between the semiconductor material constituting the contact portion (51c) to the floating diffusion (FD) and the floating diffusion (FD). The metal film (51a) may include at least one metal material among Ti, TiN, Ta, TaN, and W. By forming the metal film (51a), the contact resistance with the semiconductor material is reduced, thereby reducing the degradation of charge transfer in the floating diffusion (FD).

[0094] Other configurations may be nearly identical to Configuration Example 1 or Configuration Example 2 above.

[0095] (Composition Example 6)

[0096] FIG. 16 is a cross-sectional view of the main part of a pixel (P) in configuration example 6 of an imaging device (1) according to one embodiment.

[0097] The imaging device (1) according to Configuration Example 6 has a semiconductor layer (110) that further includes a diffusion layer (61) compared to Configuration Example 5. Additionally, in the insulating layer (211), the semiconductor material constituting the wiring (41c) is formed in a first region where a reset transistor (RST) (and floating diffusion capacitance switching transistor (FDG)) is formed, and in a second region different from the first region.

[0098] 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). By doing so, a 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 constituting the wiring (41c) is n-type, it becomes possible to form a PN junction diode as the protection diode (60).

[0099] Additionally, the first region and the second region may be connected by wiring (63) using copper (Cu). For example, the gate electrode (41g) of the reset transistor (RST) and the wiring (41c) in the second region may be connected by wiring (63).

[0100] Other configurations may be nearly identical to configuration example 5 above.

[0101] (Variation Example)

[0102] For each of the above configuration examples, a selection transistor (SEL) having a wiring (41c) made of a semiconductor material may be further provided in the insulating layer (211).

[0103] [1.3 Effect]

[0104] As described above, according to the imaging device (1) as a detection device according to one embodiment, the insulating layer (211) has a thin-film transistor and a wiring (41c), and at least a portion of the wiring (41c) is composed of the same material as the semiconductor material of the thin-film transistor. By doing so, it is possible to provide a light detection device capable of optimizing the layout of the transistor in the semiconductor substrate (semiconductor layer (110)) while reducing random noise.

[0105] According to the imaging device (1) as a detection device according to one embodiment, by using local wiring (41c) made of semiconductor material, conversion efficiency can be improved and random noise can be reduced. By forming a thin-film transistor using wiring (41c) made of semiconductor material on an insulating layer (211) on a semiconductor substrate, substrate capacitance and diffusion layer capacitance can be eliminated, and the device can be formed via the shortest path. In addition, capacitance such as through-vias in a two-stage pixel can be eliminated. It is possible to reduce the number of transistors formed on the semiconductor substrate, and it is possible to enlarge the size of transistors such as amplifier transistors (AMP), increase Qs, and optimize the layout.

[0106] Furthermore, the effects described in this specification are merely examples and are not limited thereto, and other effects may also exist. The same applies to the effects of other embodiments that follow.

[0107] <2. Application Examples for Moving Objects>

[0108] The technology of the present disclosure (the technology) can be applied to various products. For example, the technology of the present disclosure may be realized as a device mounted on any type of mobile body, such as automobiles, electric vehicles, hybrid electric vehicles, automatic two-wheeled vehicles, bicycles, personal mobility devices, airplanes, drones, ships, robots, etc.

[0109] FIG. 17 is a block diagram illustrating a schematic configuration example of a vehicle control system, which is an example of a moving object control system to which the technology of the present disclosure can be applied.

[0110] The vehicle control system (12000) is equipped with a plurality of electronic control units connected via a communication network (12001). In the example illustrated in FIG. 17, the vehicle control system (12000) is equipped with a drive system control unit (12010), a body system control unit (12020), an external information detection unit (12030), an internal information detection unit (12040), and an integrated control unit (12050). Additionally, as a functional configuration of the integrated control unit (12050), a microcomputer (12051), a voice-image output unit (12052), and a vehicle-mounted network interface (12053) are illustrated.

[0111] The drivetrain control unit (12010) controls the operation of devices related to the vehicle's drivetrain according to various programs. For example, the drivetrain control unit (12010) functions as a control device for a driving force generating device for generating the driving force of a vehicle, such as an internal combustion engine or a driving motor, a driving force transmission mechanism for transmitting the driving force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating the braking force of the vehicle.

[0112] The body control unit (12020) controls the operation of various devices equipped on the vehicle body according to various programs. For example, the body 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 headlights, taillights, brake lights, turn signals, or fog lights. In this case, radio waves transmitted from a portable device that replaces a key or signals from various switches may be input to the body control unit (12020). The body control unit (12020) receives the input of such radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0113] The external information detection unit (12030) detects external information of a vehicle equipped with a vehicle control system (12000). For example, an imaging unit (12031) is connected to the external information detection unit (12030). The external information detection unit (12030) captures an image of the outside of the vehicle with the imaging unit (12031) and receives the captured image. Based on the received image, the external information detection unit (12030) may perform object detection processing, such as people, vehicles, obstacles, signs, or text on the road surface, or distance detection processing.

[0114] The imaging unit (12031) is a light sensor that receives light and outputs an electrical signal according to the amount of light received. The imaging unit (12031) may output the electrical signal as an image or as measurement information. In addition, the light received by the imaging unit (12031) may be visible light or non-visible light such as infrared light.

[0115] The in-vehicle information detection unit (12040) detects information inside the vehicle. The in-vehicle information detection unit (12040) is connected to, for example, a driver state detection unit (12041) that detects the driver's state. The driver state detection unit (12041) includes, for example, a camera that captures the driver, and the in-vehicle information detection unit (12040) may calculate the driver's fatigue level or concentration level based on the detection information input from the driver state detection unit (12041), or determine whether the driver is dozing off.

[0116] The microcomputer (12051) can calculate a control target value for a driving force generating device, a steering mechanism, or a braking device based on information inside and outside the vehicle obtained from an external information detection unit (12030) or an internal information detection unit (12040), and output a control command to the drive system control unit (12010). For example, the microcomputer (12051) can perform cooperative control aimed at realizing functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or shock mitigation, following driving based on the distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning.

[0117] In addition, the microcomputer (12051) can perform cooperative control for the purpose of autonomous driving without following the driver's operation by controlling a driving force generating device, a steering mechanism, or a braking device based on surrounding information of the vehicle obtained from an external information detection unit (12030) or an internal information detection unit (12040).

[0118] Additionally, the microcomputer (12051) can output a control command to the body system control unit (12020) based on information from outside the vehicle obtained from the outside information detection unit (12030). For example, the microcomputer (12051) can perform cooperative control aimed at achieving illumination, such as switching the high beam to the low beam, by controlling the headlamps according to the position of the preceding vehicle or the opposing vehicle detected by the outside information detection unit (12030).

[0119] The voice-image output unit (12052) transmits at least one of a voice and an image output signal to an output device capable of notifying information visually or audibly to the occupants of the vehicle or to the outside of the vehicle. In the example of FIG. 17, an audio speaker (12061), a display unit (12062), and an instrument panel (12063) are exemplified as output devices. The display unit (12062) may include, for example, at least one of an onboard display and a head-up display.

[0120] FIG. 18 is a drawing illustrating an example of the installation location of the imaging unit (12031).

[0121] In FIG. 18, as an imaging unit (12031), it has imaging units (12101, 12102, 12103, 12104, 12105).

[0122] The imaging units (12101, 12102, 12103, 12104, 12105) are provided at locations such as, for example, the front nose, side mirrors, rear bumpers, back doors, and the upper part of the front glass inside the vehicle (12100). The imaging unit (12101) provided on the front nose and the imaging unit (12105) provided on the upper part of the front glass inside the vehicle mainly acquire a front image of the vehicle (12100). The imaging units (12102, 12103) provided on the side mirrors mainly acquire a side image of the vehicle (12100). The imaging unit (12104) provided on the rear bumper or back door mainly acquires a rear image of the vehicle (12100). The imaging unit (12105) provided on the upper part of the front glass of the vehicle interior is mainly used for detecting preceding vehicles, pedestrians, obstacles, signals, traffic signs, or lanes.

[0123] Additionally, FIG. 18 illustrates an example of the shooting range of the imaging units (12101 to 12104). The imaging range (12111) represents the imaging range of the imaging unit (12101) provided on the front nose, the imaging ranges (12112, 12113) represent the imaging ranges of the imaging units (12102, 12103) provided on the side mirrors, respectively, and the imaging range (12114) represents the imaging range of the imaging unit (12104) provided on the rear bumper or back door. For example, by overlapping image data captured by the imaging units (12101 to 12104), an overhead view image of the vehicle (12100) viewed from above is obtained.

[0124] At least one of the imaging units (12101 to 12104) may have a function for acquiring distance information. For example, at least one of the imaging units (12101 to 12104) may be a stereo camera composed of a plurality of imaging elements, or an imaging element having a pixel for phase difference detection.

[0125] For example, the microcomputer (12051) can determine the distance to each object within the imaging range (12111 to 12114) and the temporal change of this distance (relative speed with respect to the vehicle (12100)) based on distance information obtained from the imaging unit (12101 to 12104), and can extract as a leading vehicle the closest object on the vehicle (12100) and the object traveling at a predetermined speed (e.g., 0 km / h or higher) in approximately the same direction as the vehicle (12100). In addition, the microcomputer (12051) can set the distance between vehicles to be secured in advance immediately before the leading vehicle and perform automatic brake control (including follow-up stop control) or automatic acceleration control (including follow-up start control). In this way, cooperative control can be performed for the purpose of autonomous driving, such as driving autonomously without following the driver's operation.

[0126] For example, the microcomputer (12051) can classify and extract object data regarding objects based on distance information obtained from the imaging unit (12101 to 12104), such as two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other objects, and use this for automatic avoidance of obstacles. For example, the microcomputer (12051) identifies obstacles around the vehicle (12100) as obstacles that are visible to the driver of the vehicle (12100) and obstacles that are difficult to see. Then, the microcomputer (12051) determines a collision risk indicating the risk of collision with each obstacle, and when the collision risk is greater than a set value and there is a possibility of a collision, it can provide driving support for collision avoidance by outputting an alarm to the driver through the audio speaker (12061) or display unit (12062), or by performing forced deceleration or evasive steering through the drive system control unit (12010).

[0127] At least one of the imaging units (12101 to 12104) may be an infrared camera that detects infrared rays. For example, a microcomputer (12051) can recognize a pedestrian by determining whether a pedestrian exists in the image captured by the imaging units (12101 to 12104). This recognition of a pedestrian is performed by a procedure of extracting feature points in the image captured by the imaging units (12101 to 12104), for example, as an infrared camera, and a procedure of determining whether it is a pedestrian by performing pattern matching processing on a series of feature points representing the outline of an object. When the microcomputer (12051) determines that a pedestrian exists in the image captured by the imaging units (12101 to 12104) and recognizes the pedestrian, the voice image output unit (12052) controls the display unit (12062) to superimpose a rectangular outline for emphasis on the recognized pedestrian. Additionally, the voice and image output unit (12052) may control the display unit (12062) to display an icon representing a pedestrian, etc., at a desired location.

[0128] The foregoing has described an example of a vehicle control system to which the technology of the present disclosure may be applied. The technology of the present disclosure may be applied to the imaging unit (12031), the driver state detection unit (12041), and the imaging units (12101, 12102, 12103, 12104, 12105) among the configurations described above.

[0129] <3. Other embodiments>

[0130] The technology according to the present disclosure is not limited to the description of the above-mentioned embodiment and various modifications are possible.

[0131] For example, the present technology may also take the following configuration.

[0132] According to the present invention with the following configuration, an insulating layer has a thin-film transistor and wiring, and at least a portion of the wiring is composed of the same material as the semiconductor material of the thin-film transistor.

[0133] By doing so, it is possible to provide a photodetector device capable of optimizing the layout of transistors on a semiconductor substrate while reducing random noise.

[0134] (1)

[0135] A semiconductor substrate having a photoelectric conversion element that converts light into electricity, and

[0136] An insulating layer having at least one thin-film transistor, laminated on the semiconductor substrate.

[0137] Equipped,

[0138] The insulating layer further has wiring connecting the thin-film transistor and the semiconductor substrate, and at least a portion of the wiring is composed of the same material as the semiconductor material of the thin-film transistor.

[0139] Light detection device.

[0140] (2)

[0141] The semiconductor substrate further has at least one of a floating diffusion capacitance, a transfer transistor, and an amplifier transistor.

[0142] The light detection device described in (1) above.

[0143] (3)

[0144] The thin-film transistor comprises at least one of a reset transistor, a floating diffusion capacitance switching transistor, and a selection transistor.

[0145] The light detection device described in (2) above.

[0146] (4)

[0147] The above insulating layer further has a contact portion to the floating diffusion capacity, and

[0148] The above thin-film transistor is provided in the immediate vicinity of the above contact portion.

[0149] The light detection device described in (3) above.

[0150] (5)

[0151] The above contact portion is composed of a metal material comprising at least one of Au, Pt, Cu, Ti, W, Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn.

[0152] The light detection device described in (4) above.

[0153] (6)

[0154] The wiring composed of the semiconductor material and the contact portion composed of the metal material are configured to come into direct contact.

[0155] The light detection device described in (5) above.

[0156] (7)

[0157] In the above insulating layer, the contact portion is formed by extending the semiconductor material constituting the wiring to the semiconductor substrate.

[0158] The light detection device described in (4) above.

[0159] (8)

[0160] The semiconductor material constituting the wiring is stretched in the insulating layer to be connected to at least one of the floating diffusion capacitance provided on the semiconductor substrate and the gate electrode of the amplification transistor.

[0161] The light detection device described in (7) above.

[0162] (9)

[0163] At least one of the above reset transistor and the above 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.

[0164] The light detection device described in (8) above.

[0165] (10)

[0166] The above semiconductor substrate further has a diffusion layer,

[0167] In the insulating layer above, the semiconductor material constituting the wiring is formed in a first region where the reset transistor and the floating diffusion capacitance switching transistor are formed, and in a second region different from the first region.

[0168] In the insulating layer, the semiconductor material formed in the second region is stretched to be connected to the diffusion layer provided on the semiconductor substrate, thereby forming a diode by means of the diffusion layer and the semiconductor material connected to the diffusion layer.

[0169] The light detection device described in (9) above.

[0170] (11)

[0171] At least, a metal film is formed between the semiconductor material constituting the contact portion to the floating diffusion capacity and the floating diffusion capacity.

[0172] A light detection device described in any one of (7) to (10) above.

[0173] (12)

[0174] The metal film comprises at least one metal material among Ti, TiN, Ta, TaN, and W.

[0175] The light detection device described in (11) above.

[0176] (13)

[0177] The semiconductor material of the thin-film transistor comprises at least one material selected from oxide semiconductor, hydride amorphous silicon, and low-temperature polysilicon.

[0178] A light detection device described in any one of claims (1) to (12) above.

[0179] (14)

[0180] The above thin-film transistor is,

[0181] A gate insulating film comprising at least one material selected from silicon oxide, silicon nitride, Al2O3, HfO2, ZrO2, LaO2, HfSiO, Y2O3, and SiON, and

[0182] A gate electrode comprising at least one metal material selected from Au, Pt, Cu, Ti, W, Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn.

[0183] having

[0184] A light detection device described in any one of claims (1) to (13) above.

[0185] This application claims priority based on Japanese Patent Application No. 2023-212394 filed with the Japan Patent Office on December 15, 2023, and incorporates all contents of this application by reference.

[0186] A person skilled in the art would understand that various modifications, combinations, sub-combinations, and changes may be made depending on design requirements or other factors, but these are included within the scope of the appended claims or equivalents.

Claims

Claim 1 A light detection device comprising a semiconductor substrate having a photoelectric conversion element that converts light into photoelectric, 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 and the semiconductor substrate, and at least a portion of the wiring is composed of the same material as the semiconductor material of the thin-film transistor. Claim 2 In claim 1, the semiconductor substrate further comprises at least one of a floating diffusion capacitance, a transfer transistor, and an amplification transistor, forming a photodetector. Claim 3 In paragraph 2, the thin-film transistor comprises at least one of a reset transistor, a floating diffusion capacitance switching transistor, and a selection transistor. Claim 4 In paragraph 3, the insulating layer further has a contact portion to the floating diffusion capacitance, and the thin-film transistor is provided in the immediate vicinity of the contact portion. Claim 5 In claim 4, the light detection device is composed of a metal material comprising at least one of Au, Pt, Cu, Ti, W, Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn. Claim 6 A light detection device according to claim 5, wherein the wiring composed of the semiconductor material and the contact portion composed of the metal material are configured to come into direct contact. Claim 7 A light detection device according to claim 4, wherein, in the insulating layer, the semiconductor material constituting the wiring is extended to the semiconductor substrate to form the contact portion. Claim 8 A light detection device according to claim 7, wherein the semiconductor material constituting the wiring is stretched in the insulating layer to be connected to at least one of the floating diffusion capacitance provided on the semiconductor substrate and the gate electrode of the amplification transistor. Claim 9 In claim 8, 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. Claim 10 In claim 9, 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 where the reset transistor and the floating diffusion capacitance switching transistor are formed and in a second region different from the first region, and in the insulating layer, the semiconductor material formed in the second region is stretched so as to be connected to the diffusion layer provided on the semiconductor substrate, thereby forming a diode by the diffusion layer and the semiconductor material connected to the diffusion layer. Claim 11 In claim 7, a light detection device having a metal film formed between the semiconductor material constituting the contact portion to the floating diffusion capacity and the floating diffusion capacity. Claim 12 In claim 11, the metal film comprises at least one metal material among Ti, TiN, Ta, TaN, and W. A light detection device. Claim 13 A light detection device according to claim 1, wherein the semiconductor material of the thin-film transistor comprises at least one material selected from oxide semiconductor, hydride amorphous silicon, and low-temperature polysilicon. Claim 14 The light detection device according to claim 1, wherein the thin-film transistor comprises a gate insulating film comprising at least one material selected from silicon oxide, silicon nitride, Al2O3, HfO2, ZrO2, LaO2, HfSiO, Y2O3, and SiON, and a gate electrode comprising at least one metal material selected from Au, Pt, Cu, Ti, W, Pd, TiN, TaN, TiAl, Bi, In, Al, Sc, Co, and Mn.

Images