Photoelectric converter and photodetection system

Abstract

This invention provides a technology for effectively reducing noise caused by through-holes and through-electrodes in a photoelectric conversion device constructed by stacking multiple substrates. [Solution] The photoelectric conversion device comprises a first semiconductor layer on which a photoelectric conversion element is provided, a second semiconductor layer having a first surface and a second surface opposite to the first surface, with an element electrically connected to the photoelectric conversion element provided on the first surface, a through electrode provided in a through hole penetrating the second semiconductor layer, a fixed charge layer provided in contact with the inner surface of the through hole, a first insulating layer provided between the fixed charge layer and the through electrode, and a second insulating layer made of an insulating material containing silicon and provided in contact with the second surface.

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion device and a photodetection system.

Background Art

[0002] Patent Document 1 describes an image sensor configured by stacking a plurality of structures each including a semiconductor substrate. In Patent Document 1, as one of the structures for electrically connecting between these plurality of structures, a through electrode provided in a through hole penetrating the semiconductor substrate is shown.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, no special consideration is given to through holes and through electrodes, and noise may occur due to providing through holes and through electrodes in the semiconductor substrate.

[0005] An object of the present invention is to provide a technique for effectively reducing the effect of noise caused by through holes and through electrodes in a photoelectric conversion device configured by stacking a plurality of substrates.

Means for Solving the Problems

[0006] One disclosure of this specification provides a photoelectric conversion device comprising: a first semiconductor layer on which a photoelectric conversion element is provided; a second semiconductor layer having a first surface and a second surface opposite to the first surface, with an element electrically connected to the photoelectric conversion element provided on the first surface; a through electrode provided in a through hole penetrating the second semiconductor layer; a fixed charge layer provided in contact with the inner surface of the through hole; a first insulating layer provided between the fixed charge layer and the through electrode; and a second insulating layer made of an insulating material containing silicon and provided in contact with the second surface. [Effects of the Invention]

[0007] According to the present invention, in a photoelectric conversion device constructed by stacking multiple substrates, noise caused by through-holes and through-electrodes can be effectively reduced. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing an example configuration of a photoelectric conversion device according to the first embodiment. [Figure 2] This is a block diagram showing another configuration example of the photoelectric conversion device according to the first embodiment. [Figure 3] This is a block diagram showing an example of the pixel configuration of a photoelectric converter according to the first embodiment. [Figure 4] This diagram illustrates the basic operation of the photoelectric conversion unit in the photoelectric conversion device according to the first embodiment. [Figure 5] This is a perspective view showing an example of the configuration of a photoelectric conversion device according to the first embodiment. [Figure 6] This is a schematic cross-sectional view showing the structure of a photoelectric conversion device according to the first embodiment. [Figure 7] This is a schematic cross-sectional view of a through electrode in a photoelectric conversion device according to the first embodiment. [Figure 8] This is a cross-sectional view showing a process for manufacturing a photoelectric converter according to the first embodiment. [Figure 9] This is a cross-sectional view showing a process for manufacturing a photoelectric converter according to the first embodiment. [Figure 10]It is a process cross-sectional view showing a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 11] It is a process cross-sectional view showing a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 12] It is a schematic cross-sectional view showing the structure of a photoelectric conversion device according to the second embodiment. [Figure 13] It is a schematic cross-sectional view showing the structure of a photoelectric conversion device according to the third embodiment. [Figure 14] It is a schematic cross-sectional view of a through electrode in a photoelectric conversion device according to the third embodiment. [Figure 15] It is a process cross-sectional view showing a method for manufacturing a photoelectric conversion device according to the third embodiment. [[ID=I16]] [Figure 16] It is a process cross-sectional view showing a method for manufacturing a photoelectric conversion device according to the third embodiment. [Figure 17] It is a schematic cross-sectional view showing the structure of a photoelectric conversion device according to the fourth embodiment. [Figure 18] It is a block diagram showing a schematic configuration of a light detection system according to the fifth embodiment. [Figure 19] It is a block diagram showing a schematic configuration of a distance image sensor according to the sixth embodiment. [Figure 20] It is a schematic diagram showing a configuration example of an endoscopic surgery system according to the seventh embodiment. [Figure 21] It is a schematic diagram showing a configuration example of a moving body according to the eighth embodiment. [Figure 22] It is a block diagram showing a schematic configuration of a light detection system according to the eighth embodiment. [Figure 23] It is a flowchart showing the operation of a light detection system according to the eighth embodiment. [Figure 24] It is a schematic diagram showing a schematic configuration of a light detection system according to the ninth embodiment.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. In the following description, terms indicating specific directions or positions (for example, "up", "down", "right", "left", and other terms including these terms) are used as necessary. The use of these terms is for facilitating the understanding of the embodiments with reference to the drawings, and the technical scope of the present invention is not limited by the meanings of these terms. In addition, the sizes and positional relationships of the members shown in each drawing may be exaggerated for clarity of explanation.

[0010] In each of the embodiments described below, as an example of a semiconductor device, a photoelectric conversion device for imaging applications will be mainly described. However, each embodiment is not limited to the photoelectric conversion device for imaging applications, and is also applicable to other semiconductor devices. For example, other examples of the photoelectric conversion device include a distance measuring device (a device for distance measurement using focus detection or TOF (Time Of Flight)), a photometric device (a device for measuring the amount of incident light), and the like.

[0011] [First Embodiment] The schematic configuration of the photoelectric conversion device according to the first embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a block diagram showing the schematic configuration of the photoelectric conversion device according to the present embodiment.

[0012] As shown in FIG. 1, the photoelectric conversion device 100 according to the present embodiment includes a pixel region 10, a vertical scanning circuit section 40, a readout circuit section 50, a horizontal scanning circuit section 60, a DFE (Digital Front End) 70, a TX (Transmitter Circuit Section) 80, and a control pulse generation section 90.

[0013] The pixel region 10 is provided with multiple pixels 12 arranged in an array such that they form multiple rows and multiple columns. Each pixel 12 may consist of a photoelectric conversion unit including a photoelectric conversion element and a signal processing unit that processes the signal output from the photoelectric conversion unit, as will be described later. The number of pixels 12 constituting the pixel region 10 is not particularly limited. For example, the pixel region 10 can be composed of multiple pixels 12 arranged in an array of several thousand rows x several thousand columns, as in a typical digital camera. Alternatively, the pixel region 10 may be composed of multiple pixels 12 arranged in one row or one column. Alternatively, the pixel region 10 may be composed of a single pixel 12.

[0014] Each row of the pixel array in the pixel region 10 has a control line 14 extending in a first direction (horizontal direction in Figure 1). The control line 14 is connected to each pixel 12 arranged in the first direction and forms a common signal line for these pixels 12. The first direction in which the control line 14 extends is sometimes called the row direction or horizontal direction. Each of the control lines 14 may include multiple signal lines for supplying multiple types of control signals to the pixels 12.

[0015] Furthermore, each column of the pixel array in the pixel region 10 has an output line 16 extending in a second direction (vertical direction in Figure 1) that intersects the first direction. The output line 16 is connected to each of the pixels 12 arranged in the second direction, forming a common signal line for these pixels 12. The second direction in which the output line 16 extends is sometimes called the column direction or the vertical direction. Each of the output lines 16 may include multiple signal lines for transferring multi-bit digital signals output from the pixels 12 bit by bit.

[0016] Each row's control line 14 is connected to the vertical scanning circuit unit 40. The vertical scanning circuit unit 40 is a control circuit that receives control signals output from the control pulse generation unit 90, generates control signals to drive the pixels 12, and supplies them to the pixels 12 via the control lines 14. Logic circuits such as shift registers and address decoders may be used in the vertical scanning circuit unit 40. The vertical scanning circuit unit 40 sequentially scans the pixels 12 within the pixel area 10 row by row and outputs the pixel signal of each pixel 12 to the readout circuit unit 50 via the output line 16.

[0017] Each output line 16 of a column is connected to the readout circuit 50. The readout circuit 50 includes a plurality of holding units (not shown) corresponding to each column of the pixel array of the pixel region 10, and has the function of holding the pixel signals of the pixels 12 of each column, which are output row by row from the pixel region 10 via the output line 16, in the holding unit of the corresponding column.

[0018] The horizontal scanning circuit unit 60 is a control circuit that receives a control signal output from the control pulse generation unit 90, generates a control signal for reading pixel signals from the holding units of each column of the reading circuit unit 50, and supplies it to the reading circuit unit 50. Logic circuits such as shift registers and address decoders may be used in the horizontal scanning circuit unit 60. The horizontal scanning circuit unit 60 sequentially scans the holding units of each column of the reading circuit unit 50 and sequentially outputs the pixel signals held in each to the DFE 70.

[0019] DFE70 is a signal processing circuit that performs predetermined digital signal processing on the pixel signals output from the readout circuit 50. DFE70 sequentially outputs the digitally processed pixel signals to TX80.

[0020] TX80 is a circuit unit that has an external interface circuit and outputs the pixel signal output from the readout circuit unit 50 to the outside of the photoelectric converter 100. The external interface circuit provided by TX80 is not particularly limited. For example, a SerDes (SERializer / DESerializer) transmission circuit can be applied as an external interface circuit. Examples of SerDes transmission circuits include an LVDS (Low Voltage Differential Signaling) circuit and an SLVS (Scalable Low Voltage Signaling) circuit.

[0021] The control pulse generation unit 90 is a control circuit that generates control signals to control the operation and timing of the vertical scanning circuit unit 40, the readout circuit unit 50, and the horizontal scanning circuit unit 60, and supplies them to each functional block. At least a portion of the control signals that control the operation and timing of the vertical scanning circuit unit 40, the readout circuit unit 50, and the horizontal scanning circuit unit 60 may be supplied from outside the photoelectric converter 100.

[0022] Note that the connection configuration of each functional block of the photoelectric converter 100 is not limited to the configuration example shown in Figure 1, and can also be configured as shown in Figure 2, for example.

[0023] In the configuration example shown in Figure 2, output lines 16 extending in a first direction are provided for each row of the pixel array in the pixel region 10. Each output line 16 is connected to a pixel 12 aligned in the first direction, forming a common signal line for these pixels 12. Additionally, control lines 18 extending in a second direction are provided for each column of the pixel array in the pixel region 10. Each control line 18 is connected to a pixel 12 aligned in the second direction, forming a common signal line for these pixels 12.

[0024] Each row's control line 18 is connected to the horizontal scanning circuit unit 60. The horizontal scanning circuit unit 60 receives a control signal output from the control pulse generation unit 90, generates a control signal for reading pixel signals from the pixels 12, and supplies it to the pixels 12 via the control lines 18. Specifically, the horizontal scanning circuit unit 60 sequentially scans multiple pixels 12 in the pixel area 10 in column units and outputs the pixel signals of the pixels 12 in each row belonging to the selected column to the output line 16.

[0025] Each row's output line 16 is connected to the readout circuit unit 50. The readout circuit unit 50 includes a plurality of holding units (not shown) corresponding to each row of the pixel array in the pixel area 10, and has the function of holding the pixel signals of the pixels 12 of each row, which are output column by column from the pixel area 10 via the output line 16, in the holding unit of the corresponding row.

[0026] The readout circuit 50 receives a control signal output from the control pulse generation unit 90 and sequentially outputs the pixel signals held in the holding unit for each row to the DFE 70. Other configurations in the example configuration shown in Figure 2 may be the same as those in the example configuration shown in Figure 1.

[0027] Figure 3 is a block diagram showing an example of the pixel configuration of a photoelectric converter according to this embodiment. Each pixel 12 has a photoelectric conversion unit 20 and a signal processing unit 30, as shown in Figure 3. The photoelectric conversion unit 20 has a photoelectric conversion element 22 and outputs a signal corresponding to the incident light. The signal processing unit 30 is a signal processing circuit that processes the signal output from the photoelectric conversion unit 20. The signal processing unit 30 has a functional block 30A including a quench circuit 32 and a waveform shaping circuit 34, and a functional block 30B including a selection circuit 38 and a processing circuit 36. In the pixel configuration shown in Figure 3, the control lines 14 of each row may include a signal line 14A to which a control signal pRES is supplied from the vertical scanning circuit unit 40, and a signal line 14B to which a control signal pSEL is supplied from the vertical scanning circuit unit 40.

[0028] The photoelectric conversion element 22 may be an avalanche photodiode (hereinafter referred to as "APD"). The anode of the APD constituting the photoelectric conversion element 22 is connected to a node to which voltage VL is supplied. The cathode of the APD constituting the photoelectric conversion element 22 is connected to one terminal of the quench circuit 32. The connection node between the photoelectric conversion element 22 and the quench circuit 32 is the output node of the photoelectric conversion unit 20. The other terminal of the quench circuit 32 is connected to a node to which a voltage VH higher than voltage VL is supplied. Voltages VL and VH are set so that a reverse bias voltage sufficient for the APD to perform avalanche multiplication operation is applied. In one example, a negative high voltage is applied as voltage VL, and a positive voltage of about the power supply voltage is applied as voltage VH. For example, voltage VL is -30V and voltage VH is 1V.

[0029] The photoelectric conversion element 22 can be composed of an APD as described above. By supplying the APD with a reverse bias voltage sufficient for avalanche multiplication, the carriers generated by the incidence of light on the APD undergo avalanche multiplication, and an avalanche current is generated. There are two operating modes when a reverse bias voltage is supplied to the APD: Geiger mode and linear mode. Geiger mode is an operating mode in which the voltage applied between the anode and cathode is a reverse bias voltage greater than the breakdown voltage of the APD. Linear mode is an operating mode in which the voltage applied between the anode and cathode is a reverse bias voltage near or below the breakdown voltage of the APD. An APD operating in Geiger mode is called a SPAD (Single Photon Avalanche Diode). The APD constituting the photoelectric conversion element 22 may operate in linear mode or in Geiger mode, but a SPAD is more preferable because it has a larger potential difference than a linear mode APD and the effect of improving the signal-to-noise ratio is more pronounced.

[0030] In the circuit configuration shown in Figure 3, the anode of the APD is at a fixed potential and the signal is taken from the cathode side. However, the cathode of the APD may also be at a fixed potential and the signal may be taken from the anode side. In the former case, the signal charge is an electron. In the latter case, the signal charge is a hole. Furthermore, although this embodiment describes the case where one node of the APD is at a fixed potential, the potentials of both nodes may fluctuate.

[0031] The quench circuit 32 has the function of converting the change in avalanche current generated in the photoelectric conversion element 22 into a voltage signal. Furthermore, the quench circuit 32 functions as a load circuit (quench circuit) during signal multiplication by avalanche multiplication, reducing the voltage applied to the photoelectric conversion element 22 and suppressing avalanche multiplication. The operation by which the quench circuit 32 suppresses avalanche multiplication is called the quench operation. The quench circuit 32 also has the function of returning the voltage supplied to the photoelectric conversion element 22 to voltage VH by allowing current to flow to compensate for the voltage drop caused by the quench operation. The operation by which the quench circuit 32 returns the voltage supplied to the photoelectric conversion element 22 to voltage VH is called the recharge operation. The quench circuit 32 can be composed of resistive elements, MOS transistors, and the like.

[0032] The waveform shaping circuit 34 has an input node to which the output signal from the photoelectric conversion unit 20 is supplied, and an output node. The waveform shaping circuit 34 has the function of converting the analog signal supplied from the photoelectric conversion unit 20 into a pulse signal. The waveform shaping circuit 34 may be composed of logic circuits including NOT gates (inverter circuits), NOR gates, NAND gates, etc. The output node of the waveform shaping circuit 34 is connected to the processing circuit 36.

[0033] The processing circuit 36 ​​has an input node to which the output signal of the waveform shaping circuit 34 is supplied, an input node connected to the control line 14, and an output node. The processing circuit 36 ​​has the function of performing predetermined signal processing on the output signal of the waveform shaping circuit 34 and holding the processed signal or processing result. The processing circuit 36 ​​is not particularly limited, but for example it may be a counter circuit. In this case, the processing circuit 36 ​​counts the pulses superimposed on the signal output from the waveform shaping circuit 34 and holds the count value which is the counting result. The signals supplied from the vertical scanning circuit unit 40 to the processing circuit 36 ​​via the control line 14 may include an enable signal for controlling the pulse counting period (exposure period) and a reset signal for resetting the count value held by the processing circuit 36. Figure 3 shows, as an example, a reset signal (control signal pRES) supplied via the signal line 14A. The output node of the processing circuit 36 ​​is connected to the selection circuit 38.

[0034] The selection circuit 38 has the function of switching the electrical connection state (connected or disconnected) between the processing circuit 36 ​​and the output line 16. The selection circuit 38 switches the connection state between the processing circuit 36 ​​and the output line 16 in accordance with the selection signal supplied from the vertical scanning circuit unit 40 via the control line 14 (in the configuration example of Figure 2, the selection signal supplied from the horizontal scanning circuit unit 60 via the control line 18). Figure 3 shows, as an example, the selection signal (control signal pSEL) supplied via the signal line 14B. The processing circuit 36 ​​may include a buffer circuit for outputting signals.

[0035] Pixel 12 is typically a unit structure that outputs a pixel signal for forming an image. However, in cases where the purpose is distance measurement using the TOF (Time of Flight) method, pixel 12 does not necessarily have to be a unit structure that outputs a pixel signal for forming an image. That is, pixel 12 can also be a unit structure that outputs a signal for measuring the time and amount of light that arrived.

[0036] Furthermore, the signal processing unit 30 does not necessarily need to be provided for each pixel 12; a single signal processing unit 30 may be provided for multiple pixels 12. In this case, a single signal processing unit 30 can be used to sequentially perform signal processing for multiple pixels 12.

[0037] Next, the basic operation of the photoelectric conversion unit 20 in the photoelectric conversion device according to this embodiment will be explained using Figure 4. Figure 4 is a diagram illustrating the basic operation of the photoelectric conversion element 22, the quench circuit 32, and the waveform shaping circuit 34 in the photoelectric conversion device according to this embodiment. Figure 4(a) is a circuit diagram of the photoelectric conversion element 22, the quench circuit 32, and the waveform shaping circuit 34. Figure 4(b) shows the waveform of the signal at the input node (node ​​A) of the waveform shaping circuit 34. Figure 4(c) shows the waveform of the signal at the output node (node ​​B) of the waveform shaping circuit 34. For the sake of simplicity, it is assumed here that the waveform shaping circuit 34 is configured as an inverter circuit.

[0038] At time t0, a reverse bias voltage with a potential difference equivalent to (VH-VL) is applied to the photoelectric element 22. A reverse bias voltage sufficient to cause avalanche multiplication is applied between the anode and cathode of the APD constituting the photoelectric element 22, but when no photons are incident on the photoelectric element 22, there are no carriers that serve as seeds for avalanche multiplication. Therefore, avalanche multiplication does not occur in the photoelectric element 22, and no current flows through the photoelectric element 22.

[0039] At the following time t1, assume that a photon is incident on the photoelectric conversion element 22. When a photon is incident on the photoelectric conversion element 22, electron-hole pairs are generated by photoelectric conversion, and avalanche multiplication occurs using these carriers as a seed, causing an avalanche current to flow through the photoelectric conversion element 22. This avalanche current flows through the quench circuit 32, causing a voltage drop through the quench circuit 32, and the voltage at node A begins to drop. When the voltage drop at node A becomes large and avalanche multiplication stops at time t3, the voltage level at node A will no longer drop.

[0040] When the avalanche multiplication in the photoelectric conversion element 22 stops, a current flows from the node to which voltage VL is supplied through the photoelectric conversion element 22 to node A to compensate for the voltage drop, and the voltage at node A gradually increases. Subsequently, at time t5, node A settles back to its original voltage level.

[0041] The waveform shaping circuit 34 binarizes the signal input from node A according to a predetermined threshold and outputs it from node B. Specifically, the waveform shaping circuit 34 outputs a low-level signal from node B when the voltage level at node A exceeds the threshold, and outputs a high-level signal from node B when the voltage level at node A is below the threshold. For example, as shown in Figure 4(b), suppose the voltage at node A is below the threshold during the period from time t2 to time t4. In this case, as shown in Figure 4(c), the signal level at node B is low during the period from time t0 to time t2 and from time t4 to time t5, and high during the period from time t2 to time t4.

[0042] Thus, the analog signal input from node A is waveform-shaped into a digital signal by the waveform shaping circuit 34. The pulse signal output from the waveform shaping circuit 34 in response to the incidence of photons on the photoelectric conversion element 22 is the photon detection pulse signal.

[0043] The photoelectric converter 100 of this embodiment may be configured as a stacked type photoelectric converter in which multiple substrates are stacked. For example, as shown in Figure 5, the photoelectric converter 100 may be configured by stacking three substrates, a sensor substrate 110, a circuit substrate 130, and a circuit substrate 160, and electrically connecting them to each other.

[0044] In the configuration example shown in Figure 5, at least the photoelectric conversion unit 20, one of the components of the pixel 12, can be placed on the sensor substrate 110. The functional block 30A of the signal processing unit 30, one of the components of the pixel 12, can be placed on the circuit board 130. The functional block 30B of the signal processing unit 30, one of the components of the pixel 12, can be placed on the circuit board 160. Pixel regions 10 may be provided on each of the sensor substrate 110, circuit board 130, and circuit board 160 so as to overlap in a plan view. The photoelectric conversion unit 20, functional block 30A, and functional block 30B of each of the multiple pixels 12 constituting the pixel region 10 may be provided on the sensor substrate 110, circuit board 130, and circuit board 160, respectively, so as to overlap in a plan view. In this specification, a plan view means viewing from a direction perpendicular to the light incident surface of the sensor substrate 110. If the light incident surface of the semiconductor layer is rough when viewed microscopically, the plan view is defined based on the light incident surface of the semiconductor layer when viewed macroscopically. The photoelectric conversion unit 20 and the functional block 30A, and the functional block 30A and the functional block 30B are electrically connected via connecting wiring (not shown) provided for each pixel 12.

[0045] Furthermore, the circuit boards 130 and 160 can be further equipped with a vertical scanning circuit section 40, a readout circuit section 50, a horizontal scanning circuit section 60, a DFE 70, a TX 80, and a control pulse generation section 90. The vertical scanning circuit section 40, the readout circuit section 50, the horizontal scanning circuit section 60, the DFE 70, the TX 80, and the control pulse generation section 90 can be arranged around the pixel area 10 on the circuit boards 130 and 160. Each of the vertical scanning circuit section 40, the readout circuit section 50, the horizontal scanning circuit section 60, the DFE 70, the TX 80, and the control pulse generation section 90 may be provided on one of the circuit boards 130 and 160, or they may be provided separately on the circuit boards 130 and 160.

[0046] By configuring a stacked photoelectric converter 100, the integration density of elements can be increased, and functionality can be enhanced. In particular, by arranging the photoelectric conversion unit 20 and the signal processing unit 30 on separate substrates, the photoelectric conversion elements 22 can be arranged at high density without sacrificing the light-receiving area of ​​the photoelectric conversion elements 22, thereby improving photon detection efficiency. Furthermore, by arranging the functional block 30A and functional block 30B of the signal processing unit 30 on separate substrates, the photoelectric conversion elements 22 can be arranged at high density while simultaneously achieving high integration and functionality of the processing circuit 36 ​​that constitutes the functional block 30B.

[0047] Although Figure 5 shows a configuration in which three substrates, sensor substrate 110, circuit substrate 130, and circuit substrate 160, are stacked, the circuits of circuit substrate 130 and circuit substrate 160 may be placed on a single substrate, resulting in a configuration of two substrates stacked. Alternatively, a configuration of four or more substrates stacked may be used.

[0048] Furthermore, while Figure 5 assumes chips diced as sensor substrate 110 and circuit boards 130, 160, the sensor substrate 110 and circuit boards 130, 160 are not limited to chips. For example, each of the sensor substrate 110 and circuit boards 130, 160 may be a wafer. Also, the sensor substrate 110 and circuit boards 130, 160 may be stacked in wafer form and then diced, or they may be made into chips and then stacked and bonded.

[0049] Figure 6 is a schematic cross-sectional view showing a more specific configuration example of the photoelectric conversion device according to this embodiment. Figure 6 shows an example of a photoelectric conversion device constructed by stacking two substrates, a sensor substrate 110 and a circuit board 130. The sensor substrate 110 has a semiconductor layer 111 having a first surface F11 and a second surface F12 opposite to the first surface, and a wiring structure layer 121 provided on the side of the semiconductor layer 111 facing the first surface F11. The circuit board 130 has a semiconductor layer 131 having a first surface F21 and a second surface F22 opposite to the first surface F21, and a wiring structure layer 141 provided on the side of the semiconductor layer 131 facing the first surface F21.

[0050] The semiconductor layer 111 may be provided with at least one photoelectric conversion element 22 among the components of a plurality of pixels 12. Figure 6 shows the photoelectric conversion elements 22 of two adjacent pixels 12 among the plurality of pixels 12 that constitute the pixel region 10. The photoelectric conversion element 22 is configured to receive a drive voltage from the side of the first surface F11 and to output a photon detection pulse signal to the side of the first surface F11. The photoelectric conversion element 22 is configured to detect light incident from the side of the second surface F12.

[0051] The structure of the photoelectric conversion element 22 is not particularly limited. Here, as an example, we assume that a charge-collecting SPAD including N-type semiconductor regions 112, 113, 115 and P-type semiconductor regions 114, 116, 117 is provided in a semiconductor layer 111 with a low impurity concentration.

[0052] The semiconductor layer 111 is a thinned semiconductor substrate, such as a single-crystal silicon substrate, and contains a predetermined concentration of N-type or P-type impurities. In this embodiment, as an example, a semiconductor layer 111 made by thinning an N-type silicon substrate with a low impurity concentration is assumed.

[0053] The P-type semiconductor region 117 is provided on the side of the second surface F12 of the semiconductor layer 111 in a cross-sectional view. In this specification, a cross-sectional view refers to viewing a cross section of the semiconductor layer perpendicular to the light incident surface from the normal direction. The P-type semiconductor region 117 is provided over the entire region where the photoelectric conversion element 22 is arranged, and overlaps with the N-type semiconductor regions 112, 113 and the P-type semiconductor regions 114, 115, 116 in a plan view. When configuring a back-illuminated photoelectric conversion device, it is preferable to arrange the P-type semiconductor region 117 so as to be in contact with the second surface F12. By configuring it in this way, the generation of dark current on the second surface F12 can be prevented. The P-type semiconductor region 116 is provided at the boundary portion of the photoelectric conversion element 22 of adjacent pixels 12. That is, in a plan view, the P-type semiconductor region 116 is provided so as to surround each of the regions where the photoelectric conversion element 22 is arranged. The P-type semiconductor region 116 is provided from the first surface F11 of the semiconductor layer 120 to the depth to which the P-type semiconductor region 117 is located.

[0054] Inside the region enclosed by the P-type semiconductor regions 116 and 117, N-type semiconductor regions 112, 113, 115 and P-type semiconductor region 114 are provided. The N-type semiconductor region 112 is the region that constitutes the cathode of the APD and is provided on the side of the first surface F11 of the semiconductor layer 111, spaced apart from the P-type semiconductor region 116. The N-type semiconductor region 113 is provided so as to surround the periphery of the N-type semiconductor region 112. The P-type semiconductor region 114 is the region that constitutes the anode of the APD and is provided on the side of the second surface F12 than the N-type semiconductor regions 112 and 113. The P-type semiconductor region 114 is in contact with the P-type semiconductor region 116 at its peripheral edge in a plan view. The N-type semiconductor region 115 is provided between the P-type semiconductor region 114 and the P-type semiconductor region 117.

[0055] A separation structure 118 may be further provided inside the P-type semiconductor region 116. The separation structure 118 serves to prevent light from leaking into adjacent photoelectric conversion elements 22, and is preferably a wall-like structure surrounding each region in which the photoelectric conversion elements 22 are arranged. The separation structure 118 can be constructed, for example, by embedding an insulating member or a metal member in a groove formed in the semiconductor layer 111. In the example configuration shown in Figure 6, the separation structure 118 is provided so as to extend from the first surface F11 to the second surface F12 of the semiconductor layer 111, but the separation structure 118 does not necessarily have to extend from the first surface F11 to the second surface F12.

[0056] Furthermore, a ridged structure 119 may be provided on the second surface F12 of the semiconductor layer 111. The ridged structure 119 has the role of scattering light incident from the side of the second surface F12 of the semiconductor layer 111, and the pattern constituting the ridged structure 119 is not particularly limited as long as it has the function of scattering light incident from the second surface F12. The ridged structure 119 can be formed, for example, by embedding an insulating member in grooves formed on the second surface F12 of the semiconductor layer 111.

[0057] The wiring structure layer 121 may be composed of an insulating layer 122 and one or more wiring layers disposed within the insulating layer 122. These one or more wiring layers include wiring 123 electrically connected to the photoelectric conversion element 22 and wiring 124 composed of the uppermost wiring layer furthest from the first surface F11.

[0058] The semiconductor layer 131 is provided with elements that constitute the signal processing unit 30, vertical scanning circuit unit 40, readout circuit unit 50, horizontal scanning circuit unit 60, DFE 70, TX 80, and control pulse generation unit 90 of the pixel 12. Figure 6 shows an example of the elements that constitute these functional blocks, namely an N-type transistor 133N and a P-type transistor 133P. At least some of these elements are electrically connected to a photoelectric conversion element 22 provided on the semiconductor layer 111. An element isolation section 132 is provided on the first surface F21 of the semiconductor layer 131 to separate these elements. A silicide layer 135 is provided on the active region of the first surface F21 defined by the element isolation section 132 and on the gate electrodes 134 of the N-type transistor 133N and the P-type transistor 133P. The semiconductor layer 131 is also provided with a through-electrode 149. The through-electrode 149 is provided in a through-hole that penetrates between the first surface F21 and the second surface F22 of the semiconductor layer 131.

[0059] The wiring structure layer 141 may be composed of an insulating layer 142 and one or more wiring layers disposed within the insulating layer 142. These one or more wiring layers include wiring 145 connected to elements of the semiconductor layer 131 via contact plugs 143, contact plugs 144 connected to through electrodes 149, and wiring 146 composed of the uppermost wiring layer furthest from the first surface F21.

[0060] The sensor substrate 110 and the circuit board 130 are joined face to face such that the first surface F11 side of the semiconductor layer 111 on which the wiring structure layer 121 is located faces the first surface F21 side of the semiconductor layer 131 on which the wiring structure layer 141 is located faces. In other words, the joining surface between the sensor substrate 110 and the circuit board 130 is formed by the interface between the wiring structure layer 121 and the wiring structure layer 141. The electrical connection between the sensor substrate 110 and the circuit board 130 can be formed by a metal joint between the uppermost metal wiring (wiring 124) constituting the wiring structure layer 121 and the uppermost metal wiring (wiring 146) constituting the wiring structure layer 141.

[0061] A wiring structure layer 151 is provided on the second surface F22 side of the semiconductor layer 131. The wiring structure layer 151 has an insulating layer 152 and one or more wiring layers disposed within the insulating layer 152. These one or more wiring layers include wiring 153 that is electrically connected to a through electrode 149. The wiring 153 is electrically connected to a contact plug 144 provided on the wiring structure layer 141 via the through electrode 149. Alternatively, a circuit board separate from the circuit board 130 may be bonded instead of the wiring structure layer 151.

[0062] An optical structure layer 181 is provided on the second surface F12 side of the semiconductor layer 111. The optical structure layer 181 may consist of, for example, a pinning film 182, a planarization layer 183, and a microlens layer containing a plurality of microlenses ML. The optical structure layer 181 may further include a filter layer (not shown). Various optical filters such as color filters, infrared light cut filters, and monochrome filters can be applied to the filter layer.

[0063] The photoelectric converter of this embodiment is a so-called back-illuminated photoelectric converter that detects light incident from the second surface F12, which is the back surface side of the semiconductor layer 111, via the optical structural layer 181. However, the photoelectric converter of the present invention may also be configured as a so-called front-illuminated photoelectric converter that detects light incident from the first surface F11, which is the front surface side of the semiconductor layer 111.

[0064] Figure 7 is an enlarged cross-sectional view of the portion where the through-electrode 149 is provided. The semiconductor layer 131 is provided with a through-hole 139 that penetrates it. If an element isolation portion 132 is provided on the first surface F21 side of the semiconductor layer 131, the through-hole 139 may be provided so as to penetrate the element isolation portion 132. In the portion of the semiconductor layer 131 where the through-hole 139 is provided, a semiconductor region 150 is provided extending from the first surface F21 side to the second surface F22. In other words, the area around the through-hole 139 that penetrates the semiconductor layer 131 is composed of the semiconductor region 150. By applying a fixed potential to the semiconductor region 150, the effect of potential changes in the through-electrode 149 can be electrostatically shielded, and the electrical influence on transistors arranged around the through-electrode 149 can be reduced. The semiconductor region 150 may be an N-type semiconductor region or a P-type semiconductor region. If the semiconductor region 150 and the well region of the transistor adjacent to the semiconductor region 150 are regions of different conductivity types, it is possible to suppress the leakage of dark electrons generated when forming the through-hole 139 to the adjacent transistor. A low impurity concentration region may also be provided between the semiconductor region 150 and the N-type transistor 133N. By providing a low impurity concentration region, the PN junction capacitance between the semiconductor region 150 and the N-type transistor 133N can be reduced, thereby reducing the electrical influence on transistors arranged around the through-electrode 149 that may occur due to potential changes in the through-electrode 149. A low impurity concentration region may also be provided between the semiconductor region 150 and the P-type transistor 133P. By providing a low impurity concentration region, the PN junction capacitance between the semiconductor region 150 and the P-type transistor 133P can be reduced, thereby reducing the electrical influence on transistors arranged around the through-electrode 149 that may occur due to potential changes in the through-electrode 149.

[0065] A fixed charge layer 147, an insulating layer 148, and a through electrode 149 are provided inside the through hole 139. The fixed charge layer 147 is provided so as to be in contact with the inner surface of the through hole 139. The insulating layer 148 is provided along the inner surface of the through hole 139 in which the fixed charge layer 147 is provided. Preferably, the insulating layer 148 has a thicker film thickness on the side of the first surface F21 than on the side of the second surface F22. The through electrode 149 is provided so as to fill the through hole 139 in which the fixed charge layer 147 and the insulating layer 148 are provided. The through electrode 149 is electrically connected to a contact plug 144, which is provided as a connecting member as part of the wiring structure layer 141, at the end of the semiconductor layer 131 on the side of the first surface F21. The through electrode 149 is also electrically connected to a wiring 153, which is provided as part of the wiring structure layer 151, at the end of the semiconductor layer 131 on the side of the second surface F22.

[0066] The fixed charge layer 147 is a layer having a fixed charge, for example, a negative fixed charge. The fixed charge layer 147 can be made of, for example, hafnium oxide, zirconium oxide, aluminum oxide, titanium oxide, tantalum oxide, etc. By providing the fixed charge layer 147 on the inner surface of the through hole 139, holes can be induced near the inner surface of the through hole 139. By recombining dark electrons caused by etching damage during the formation of the through hole 139 with these holes, the generation of electrons contributing to noise signals can be reduced. The fixed charge layer 147 may also be a layer having a positive fixed charge. In that case, by providing the fixed charge layer 147 on the inner surface of the through hole 139, electrons can be induced near the inner surface of the through hole 139. By recombining holes caused by etching damage during the formation of the through hole 139 with these electrons, the generation of holes contributing to noise signals can be reduced.

[0067] On the other hand, the fixed charge layer 147 is not in contact with the second surface F22 of the semiconductor layer 131. Instead, the insulating layer 152 is in contact with the second surface F22 of the semiconductor layer 131. This is because if a film with fixed charges were in contact with the second surface F22 of the semiconductor layer 131, the depletion layer region of the semiconductor element (e.g., a MOS transistor) provided on the semiconductor layer 131 would come into contact with the fixed charge layer 147, potentially causing leakage current to occur between the semiconductor elements.

[0068] From this viewpoint, the insulating layer 152 may preferably be an insulating material containing silicon, such as silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiON), silicon carbide (SiC), or silicon carbonitride (SiCN). It is sufficient that at least the portion of the insulating layer 152 in contact with the second surface F22 of the semiconductor layer 131 is made of one of these insulating materials that does not contain fixed charges. The insulating layer 148 may be made of an insulating material containing silicon, similar to the insulating layer 152. The through-electrode 149 may be made of a conductive material such as tungsten, aluminum, or copper.

[0069] Next, the method for manufacturing the photoelectric converter according to this embodiment will be described with reference to Figures 8 to 11. Figures 8 to 11 are cross-sectional views showing the process for manufacturing the photoelectric converter according to this embodiment.

[0070] First, a semiconductor layer (semiconductor substrate) 111 having a first surface F11 and a second surface F12' is prepared, and at least one of the components of a plurality of pixels 12, a photoelectric conversion element 22, is formed on the first surface F11 side of this semiconductor layer 111. Next, a wiring structure layer 121 is formed on the first surface F11 of the semiconductor layer 111, in which one or more wiring layers containing wirings 123, 124 are provided within an insulating layer 122. In this way, a sensor substrate 110 including the semiconductor layer 111 and the wiring structure layer 121 is formed (Figure 8(a)).

[0071] In addition, a semiconductor layer (semiconductor substrate) 131 having a first surface F21 and a second surface F22' is prepared separately from the sensor substrate 110, and elements constituting other components of the pixel 12 and peripheral circuit blocks are formed on the first surface F21 side of this semiconductor layer 131. Next, a wiring structure layer 141 is formed on the first surface F21 of the semiconductor layer 131, in which one or more wiring layers including contact plugs 143, 144 and wiring 145, 146 are provided within an insulating layer 142. In this way, a circuit board 130 including the semiconductor layer 131 and the wiring structure layer 141 is formed (Figure 8(b)).

[0072] Next, the sensor substrate 110 and the circuit board 130 prepared in this manner are joined face to face, such that the first surface F11, which is the front side of the semiconductor layer 111, and the first surface F21, which is the front side of the semiconductor layer 131, face each other (Figure 8(c)). At this time, the sensor substrate 110 and the circuit board 130 can be electrically connected by forming a metal joint between the uppermost metal wiring (wiring 124) of the wiring structure layer 121 and the uppermost metal wiring (wiring 146) of the wiring structure layer 141.

[0073] Next, the semiconductor layer 131 of the circuit board 130 is polished from the second surface F22' side, for example, by chemical mechanical polishing (CMP), to thin it. The surface newly formed by polishing the semiconductor layer 131 is the second surface F22 of the semiconductor layer 131 (Figure 9(a)). It is preferable to process the semiconductor layer 131 of the circuit board 130 to be thinner, as this makes it easier to electrically isolate wells of the same conductivity type and improves design flexibility. From the viewpoint of reducing the influence of leakage current caused by defects remaining near the second surface F22 after thinning the semiconductor layer 131, the impurity concentration in the depth direction of the well may be distributed.

[0074] Next, a through-hole 139 reaching the contact plug 144 is formed in the semiconductor layer 131 using photolithography and dry etching (Figure 9(b)). In this case, it is preferable that the through-hole 139 has a tapered shape in which the opening width on the second surface F22 side is larger than the opening width on the first surface F21 side. By making the through-hole 139 such a shape, film deposition inside the through-hole 139 is made easier, and the uniformity of the film thickness of the fixed charge layer 147 and the insulating layer 148 inside the through-hole 139 and the embedding characteristics of the through-electrode 149 can be improved. Furthermore, from the viewpoint of suppressing dark current caused by etching damage, it is preferable to perform chemical dry etching to remove surface damage to the through-hole 139. In addition, it is preferable that the opening width on the first surface F21 side of the through-hole 139 be formed to be sufficiently larger than the diameter of the contact plug 144. This increases the contact area between the through-electrode 149 and the contact plug 144, suppressing contact failures caused by manufacturing variations and reducing conductivity failures.

[0075] Next, a film with a fixed charge is deposited on the entire surface of the second surface F22, including the through-hole 139, for example by atomic layer deposition (ALD), to form a fixed charge layer 147 (Figure 10(a)). The fixed charge layer 147 may be composed of, for example, hafnium oxide, zirconium oxide, aluminum oxide, titanium oxide, tantalum oxide, etc. In the following drawings, for simplification, some parts of the semiconductor layer 111 and the wiring structure layer 121 are omitted.

[0076] Next, the fixed charge layer 147 is etched back from the second surface F22 side by anisotropic etching, selectively removing the fixed charge layer 147 from the surface of the second surface F22 and the bottom of the through hole 139. This removes the fixed charge layer 147 from the surface of the second surface F22 while leaving some of the fixed charge layer 147 on the side walls of the through hole 139, thus exposing the contact plug 144 again at the bottom of the through hole 139 (Figure 10(b)).

[0077] Next, an insulating material such as SiO, SiN, SiC, or SiCN is deposited on the entire surface of the second surface F22, including the through-hole 139 where the fixed charge layer 147 is provided, by chemical vapor deposition (CVD), for example, to form an insulating layer 148 (Figure 10(c)). The insulating layer 148 may be formed such that the thickness of the insulating layer 148 on the first surface F21 side is greater than the thickness of the insulating layer 148 on the second surface F22 side. Doing so reduces the likelihood of voids forming within the through-hole 139 when the conductive material is deposited within it in the subsequent steps, thus reducing variations in electrical resistance.

[0078] Next, the insulating layer 148 is etched back from the second surface F22 side by anisotropic etching, selectively removing the insulating layer 148 from the surface of the second surface F22 and the bottom of the through hole 139. This removes the insulating layer 148 from the surface of the second surface F22 while leaving the insulating layer 148 on the side wall portion of the through hole 139 where the fixed charge layer 147 is provided, and re-exposing the contact plug 144 at the bottom of the through hole 139 (Figure 11(a)).

[0079] Next, a conductive material such as tungsten, aluminum, or copper is deposited on the entire surface of the second surface F22, including the inside of the through-hole 139, by methods such as CVD or sol-gel deposition. Subsequently, the conductive material on the second surface F22 is removed by anisotropic etching or CMP so that the conductive material remains only inside the through-hole 139. This forms a through-electrode 149 made of the conductive material embedded in the through-hole 139, which has a laminated film of a fixed charge layer 147 and an insulating layer 148 on its side portion (Figure 11(b)).

[0080] Next, a wiring structure layer 151 is formed on the second surface F22 of the semiconductor layer 131 in which the through-electrode 149 is embedded, including an insulating layer 152 and wiring 153 electrically connected to the contact plug 144 via the through-electrode 149 (Figure 11(c)). In this case, at least the portion of the insulating layer 152 that is in contact with the second surface F22 of the semiconductor layer 131 is made of an insulating material containing silicon such as SiO, SiN, SiON, SiC, or SiCN.

[0081] Next, the semiconductor layer 111 of the sensor substrate 110 is polished from the second surface F12' side, for example by CMP, until it reaches the P-type semiconductor region 117. Then, an optical structure layer 181 is formed on the second surface F12 of the semiconductor layer 111 formed by thinning, completing the photoelectric conversion device of this embodiment (see Figure 6).

[0082] Thus, in this embodiment, a fixed charge layer is placed between the side wall of the through-hole penetrating the semiconductor layer and the through-electrode, and an insulating layer made of an insulating material containing silicon that does not contain fixed charges is provided in contact with the back surface of the semiconductor layer. Therefore, according to this embodiment, noise caused by damage during the formation of the through-hole and through-electrode can be effectively reduced.

[0083] [Second Embodiment] A photoelectric conversion device according to a second embodiment of the present invention will be described with reference to Figure 12. Figure 12 is a schematic cross-sectional view showing an example of the configuration of the photoelectric conversion device according to this embodiment. Components similar to those in the photoelectric conversion device according to the first embodiment are denoted by the same reference numerals, and their descriptions are omitted or simplified.

[0084] As shown in Figure 12, the photoelectric conversion device 100 according to this embodiment is formed by stacking a sensor substrate 110, a circuit board 130, and a circuit board 160. The sensor substrate 110 has a semiconductor layer 111 having a first surface F11 and a second surface F12 opposite to the first surface F11, and a wiring structure layer 121 provided on the side of the semiconductor layer 111 facing the first surface F11. The circuit board 130 has a semiconductor layer 131 having a first surface F21 and a second surface F22 opposite to the first surface F21, a wiring structure layer 141 provided on the side of the semiconductor layer 131 facing the first surface F21, and a wiring structure layer 151 provided on the side of the semiconductor layer 131 facing the second surface F22. The circuit board 160 has a semiconductor layer 161 having a first surface F31 and a second surface F32 opposite to the first surface F31, and a wiring structure layer 171 provided on the side of the semiconductor layer 161 facing the first surface F31. The wiring structure layer 171 comprises an insulating layer 172 and one or more wiring layers arranged therein. This one or more wiring layers include wiring 173, which is composed of the uppermost wiring layer furthest from the first surface F31.

[0085] The sensor substrate 110 and the circuit board 130 are joined face-to-back such that the first surface F11 of the semiconductor layer 111 on which the wiring structure layer 121 is located faces the second surface F22 of the semiconductor layer 131 on which the wiring structure layer 151 is located. In other words, the joining surface between the sensor substrate 110 and the circuit board 130 is formed by the interface between the wiring structure layer 121 and the wiring structure layer 151. The electrical connection between the sensor substrate 110 and the circuit board 130 can be formed by a metal joint between the uppermost metal wiring (wiring 124) constituting the wiring structure layer 121 and the uppermost metal wiring (wiring 154) constituting the wiring structure layer 151.

[0086] Circuit boards 130 and 160 are joined face-to-face such that the first surface F21 side of semiconductor layer 131 on which the wiring structure layer 141 is located faces the first surface F31 side of semiconductor layer 161 on which the wiring structure layer 171 is located. In other words, the joining surface between circuit board 130 and circuit board 160 is formed by the interface between wiring structure layer 141 and wiring structure layer 171. The electrical connection between circuit board 130 and circuit board 160 can be formed by a metal joint between the uppermost metal wiring (wiring 146) constituting the wiring structure layer 141 and the uppermost metal wiring (wiring 173) constituting the wiring structure layer 171.

[0087] Thus, the photoelectric converter of this embodiment is a back-illuminated type photoelectric converter similar to that of the first embodiment. On the other hand, the photoelectric converter of this embodiment differs from the photoelectric converter of the first embodiment, in that the sensor substrate 110 and the circuit board 130 are joined face to face, in that the sensor substrate 110 and the circuit board 130 are joined face to back. By joining the sensor substrate 110 and the circuit board 130 face to back, the distance from the light incident surface to the MOS transistors arranged in the semiconductor layer 131 can be increased, and thus the characteristic fluctuations of the MOS transistors can be suppressed compared to the first embodiment.

[0088] In the photoelectric conversion device of this embodiment, the through electrode 149 may have the same configuration as in the first embodiment.

[0089] Thus, according to this embodiment, similar to the first embodiment, noise caused by damage during the formation of through holes and through electrodes can be effectively reduced.

[0090] [Third Embodiment] A photoelectric conversion device according to a third embodiment of the present invention will be described with reference to Figure 13. Figure 13 is a schematic cross-sectional view showing an example of the configuration of the photoelectric conversion device according to this embodiment. Components similar to those in the photoelectric conversion device according to the first or second embodiment are denoted by the same reference numerals, and their descriptions are omitted or simplified.

[0091] The photoelectric converter according to this embodiment is a back-illuminated type photoelectric converter similar to the first embodiment, but the configuration of the portion where the through-electrode 149 is located differs from that of the photoelectric converter according to the first embodiment. That is, as shown in Figure 13, the photoelectric converter according to this embodiment further has an insulating layer 137 provided between the second surface F22 of the semiconductor layer 131 and the wiring structure layer 151, and the through-electrode 149 is provided in a through-hole that penetrates the semiconductor layer 131 and the insulating layer 137. As the constituent material of the insulating layer 137, similar to the insulating layer 152 described above, an insulating material containing silicon, such as SiO, SiN, SiCN, SiC, or SiCN, can preferably be used.

[0092] Figure 14 is an enlarged cross-sectional view of the portion where the through-electrode 149 is provided. An insulating layer 137 is provided on the second surface F22 of the semiconductor layer 131. Through-holes 139 are provided in the insulating layer 137 and the semiconductor layer 131. A fixed charge layer 147, an insulating layer 148, and a through-electrode 149 are provided inside the through-hole 139. The fixed charge layer 147 is provided so as to be in contact with the inner surface of the through-hole 139. The insulating layer is provided along the inner surface of the through-hole 139 in which the fixed charge layer 147 is provided. The through-electrode 149 is provided so as to fill the through-hole 139 in which the fixed charge layer 147 and the insulating layer 148 are provided.

[0093] With this configuration, the through-electrode 149 is positioned not only within the semiconductor layer 131 but also within the insulating layer 137. This allows the through-electrode 149 to also function as a contact plug for electrically connecting to the wiring 153 positioned within the insulating layer 152, thereby simplifying the manufacturing process. In addition, it reduces poor contact between the through-electrode 149 and the wiring 153.

[0094] Furthermore, in the above configuration, the through-holes 139, the fixed charge layer 147, the insulating layer 148, and the through-electrode 149 are formed after the insulating layer 137 is formed on the semiconductor layer 131. In other words, the second surface F22 of the semiconductor layer 131 can be protected from damage during anisotropic etching when forming the fixed charge layer 147 and the insulating layer 148, and during CMP when forming the through-electrode 149. This makes it possible to suppress dark current caused by damage introduced to the second surface F22 of the semiconductor layer 131.

[0095] Next, the method for manufacturing the photoelectric converter according to this embodiment will be described with reference to Figures 15 and 16. Figures 15 and 16 are cross-sectional views showing the process for manufacturing the photoelectric converter according to this embodiment.

[0096] First, the sensor substrate 110 and the circuit board 130 are joined together in the same manner as the manufacturing method of the first embodiment shown in Figures 8(a) to 9(a), and the semiconductor layer 131 is thinned from the second surface F22' side.

[0097] Next, an insulating material such as SiO, SiN, SiON, SiC, or SiCN is deposited on the second surface F22 of the semiconductor layer 131 formed by thinning, for example, by chemical vapor deposition (CVD) or sol-gel method, to form an insulating layer 137 (Figure 15(a)). At this time, the thickness of the insulating layer 137 is set to such a degree that the second surface F22 of the semiconductor layer 131 is not exposed when the wiring 153 is formed, taking into consideration the reduction in film thickness due to processing during the formation of the through-electrode 149 and wiring 153 described later.

[0098] Next, photolithography and dry etching are used to form through holes 139 reaching the contact plug 144 in the insulating layer 137 and the semiconductor layer 131 (Figure 15(b)).

[0099] Next, a fixed charge layer 147 and an insulating layer 148 are formed on the entire surface of the second surface F22, including the insulating layer 137 and the inside of the through-hole 139, by methods such as CVD, ALD, or sol-gel (Figure 15(c)).

[0100] Next, the insulating layer 148 and the fixed charge layer 147 are etched back from the second surface F22 side by anisotropic etching, selectively removing the insulating layer 148 and the fixed charge layer 147 from the surface of the insulating layer 137 and the bottom of the through hole 139. This removes the insulating layer 148 and the fixed charge layer 147 from the surface of the insulating layer 137 while leaving the fixed charge layer 147 and the insulating layer 148 on the side walls of the through hole 139, thereby exposing the contact plug 144 again at the bottom of the through hole 139 (Figure 16(a)).

[0101] Furthermore, the etch-back of the insulating layer 148 and the fixed charge layer 147 may be performed each time the fixed charge layer 147 and the insulating layer 148 are deposited, as in the first embodiment. In addition, in the first embodiment, the insulating layer 148 and the fixed charge layer 147 may be etch-back continuously, as in this embodiment.

[0102] Next, a conductive material is deposited on the entire surface of the second surface F22, including the insulating layer 137 and the through-holes 139, by methods such as CVD or sol-gel deposition. Subsequently, the conductive material on the insulating layer 137 is removed by anisotropic etching or CMP, so that the conductive material remains only in the through-holes 139. This forms a through-electrode 149 made of conductive material embedded in the through-holes 139, which have a laminated film of a fixed charge layer 147 and an insulating layer 148 on their side portions (Figure 16(b)).

[0103] Next, a wiring structure layer 151 is formed on the insulating layer 137 in which the through electrode 149 is embedded, including wiring 153 electrically connected to the contact plug 144 via the through electrode 149, and an insulating layer 152 (Figure 16(c)).

[0104] Next, the semiconductor layer 111 of the sensor substrate 110 is polished from the second surface F12' side, for example by CMP, until it reaches the P-type semiconductor region 117. Then, an optical structure layer 181 is formed on the second surface F12 of the semiconductor layer 111 formed by thinning, completing the photoelectric conversion device of this embodiment (see Figure 13).

[0105] Thus, according to this embodiment, similar to the first embodiment, noise caused by damage during the formation of through holes and through electrodes can be effectively reduced.

[0106] [Fourth Embodiment] A photoelectric conversion device according to a fourth embodiment of the present invention will be described with reference to Figure 17. Figure 17 is a schematic cross-sectional view showing an example of the configuration of the photoelectric conversion device according to this embodiment. Components similar to those in the photoelectric conversion devices of the first to third embodiments are denoted by the same reference numerals, and their descriptions are omitted or simplified.

[0107] As shown in Figure 17, the photoelectric converter 100 according to this embodiment is formed by stacking a sensor substrate 110, a circuit board 130, and a circuit board 160. The sensor substrate 110 has a semiconductor layer 111 having a first surface F11 and a second surface F12 opposite to the first surface F11, and a wiring structure layer 121 provided on the side of the semiconductor layer 111 facing the first surface F11. The circuit board 130 has a semiconductor layer 131 having a first surface F21 and a second surface F22 opposite to the first surface F21, a wiring structure layer 141 provided on the side of the semiconductor layer 131 facing the first surface F21, and a wiring structure layer 151 provided on the side of the semiconductor layer 131 facing the second surface F22. The circuit board 160 has a semiconductor layer 161 having a first surface F31 and a second surface F32 opposite to the first surface F31, and a wiring structure layer 171 provided on the side of the semiconductor layer 161 facing the first surface F31. The wiring structure layer 171 comprises an insulating layer 172 and one or more wiring layers arranged therein. This one or more wiring layers include wiring 173, which is composed of the uppermost wiring layer furthest from the first surface F31.

[0108] The sensor substrate 110 and the circuit board 130 are joined face-to-back such that the first surface F11 of the semiconductor layer 111 on which the wiring structure layer 121 is located faces the second surface F22 of the semiconductor layer 131 on which the wiring structure layer 151 is located. In other words, the joining surface between the sensor substrate 110 and the circuit board 130 is formed by the interface between the wiring structure layer 121 and the wiring structure layer 151. The electrical connection between the sensor substrate 110 and the circuit board 130 can be formed by a metal joint between the uppermost metal wiring (wiring 124) constituting the wiring structure layer 121 and the uppermost metal wiring (wiring 154) constituting the wiring structure layer 151.

[0109] Circuit boards 130 and 160 are joined face to face such that the first surface F21 side of semiconductor layer 131 on which the wiring structure layer 141 is located faces the first surface F31 side of semiconductor layer 161 on which the wiring structure layer 171 is located. In other words, the joining surface between circuit board 130 and circuit board 160 is formed by the interface between wiring structure layer 141 and wiring structure layer 171. The electrical connection between circuit board 130 and circuit board 160 can be formed by a metal joint between the uppermost metal wiring (wiring 146) constituting the wiring structure layer 141 and the uppermost metal wiring (wiring 173) constituting the wiring structure layer 171.

[0110] Thus, the photoelectric converter of this embodiment is a back-illuminated type photoelectric converter similar to that of the first embodiment. On the other hand, the photoelectric converter of this embodiment differs from the photoelectric converter of the first embodiment, in that the sensor substrate 110 and the circuit board 130 are joined face to face, in that the sensor substrate 110 and the circuit board 130 are joined face to back. By joining the sensor substrate 110 and the circuit board 130 face to back, the distance from the light incident surface to the MOS transistors arranged in the semiconductor layer 131 can be increased, making it less likely for the characteristics of the MOS transistors to fluctuate compared to the first embodiment.

[0111] Furthermore, in this embodiment, the through electrode 149 has the same configuration as in the third embodiment, while the insulating layer 137 disposed between the semiconductor layer 131 and the wiring structure layer 151 has a multilayer structure including an insulating layer 138 with a higher refractive index than the insulating layer 152. For example, if the insulating layer 152 is made of an SiO film, the insulating layer 138 may be made of a SiN film. By making the insulating layer 137 such a multilayer structure, it is possible to more effectively prevent light incident from the light incident surface side from incident on the semiconductor layer 131 side.

[0112] Thus, according to this embodiment, similar to the first embodiment, noise caused by damage during the formation of through holes and through electrodes can be effectively reduced.

[0113] [Fifth Embodiment] A photodetection system according to a fifth embodiment of the present invention will be described with reference to Figure 18. Figure 18 is a block diagram showing the schematic configuration of the photodetection system according to this embodiment. In this embodiment, a photodetection sensor to which the photoelectric converter 100 described in the first to fourth embodiments is applied will be described.

[0114] The photoelectric converter 100 described in the first to fourth embodiments above is applicable to various light detection systems. Examples of applicable light detection systems include imaging systems such as digital still cameras, digital camcorders, surveillance cameras, photocopiers, fax machines, mobile phones, in-vehicle cameras, and observation satellites. Camera modules, which include optical systems such as lenses and imaging devices, are also included in light detection systems. Figure 18 shows a block diagram of a digital still camera as an example of these.

[0115] The photodetection system 200 illustrated in Figure 18 includes a photoelectric converter 201, a lens 202 for forming an optical image of a subject onto the photoelectric converter 201, an aperture 204 for varying the amount of light passing through the lens 202, and a barrier 206 for protecting the lens 202. The lens 202 and aperture 204 form an optical system that focuses light onto the photoelectric converter 201. The photoelectric converter 201 is the photoelectric converter 100 described in the first to fourth embodiments, which converts the optical image formed by the lens 202 into image data.

[0116] The photodetection system 200 also includes a signal processing unit 208 that processes the output signal from the photoelectric converter 201. The signal processing unit 208 generates image data from the digital signal output by the photoelectric converter 201. The signal processing unit 208 also performs various corrections and compressions as needed before outputting the image data. The photoelectric converter 201 may include an AD conversion unit that generates the digital signal processed by the signal processing unit 208. The AD conversion unit may be formed on the semiconductor layer (semiconductor substrate) on which the photon detection element of the photoelectric converter 201 is formed, or on a semiconductor substrate separate from the semiconductor layer on which the photon detection element of the photoelectric converter 201 is formed. The signal processing unit 208 may also be formed on the same semiconductor layer as the photoelectric converter 201.

[0117] The light detection system 200 further includes a memory unit 210 for temporarily storing image data, and an external interface unit (external I / F unit) 212 for communicating with an external computer or the like. Furthermore, the light detection system 200 includes a recording medium 214 such as a semiconductor memory for recording or reading imaging data, and a recording medium control interface unit (recording medium control I / F unit) 216 for recording or reading data from the recording medium 214. The recording medium 214 may be built into the light detection system 200 or it may be detachable. In addition, communication between the recording medium control I / F unit 216 and the recording medium 214, and communication from the external I / F unit 212, may be performed wirelessly.

[0118] Furthermore, the photodetection system 200 includes an overall control / calculation unit 218 that controls various calculations and the entire digital still camera, and a timing generation unit 220 that outputs various timing signals to the photoelectric converter 201 and the signal processing unit 208. Here, the timing signals and the like may be input from an external source, and the photodetection system 200 only needs to have at least the photoelectric converter 201 and the signal processing unit 208 that processes the output signals output from the photoelectric converter 201. The timing generation unit 220 may be mounted on the photoelectric converter 201. In addition, the overall control / calculation unit 218 and the timing generation unit 220 may be configured to perform some or all of the control functions of the photoelectric converter 201.

[0119] The photoelectric converter 201 outputs the imaging signal to the signal processing unit 208. The signal processing unit 208 performs predetermined signal processing on the imaging signal output from the photoelectric converter 201 and outputs image data. The signal processing unit 208 generates an image using the imaging signal. The signal processing unit 208 may also be configured to perform distance measurement calculations on the signal output from the photoelectric converter 201.

[0120] Thus, according to this embodiment, by configuring a photodetection system using the photoelectric conversion device of the first to fourth embodiments, a photodetection system capable of acquiring higher quality images can be realized.

[0121] [Sixth Embodiment] A distance image sensor according to the sixth embodiment of the present invention will be described with reference to Figure 19. Figure 19 is a block diagram showing the schematic configuration of the distance image sensor according to this embodiment. In this embodiment, the distance image sensor will be described as an example of a photodetection system to which the photoelectric conversion device 100 described in the first to fourth embodiments is applied.

[0122] As shown in Figure 19, the distance image sensor 300 according to this embodiment may be configured to include an optical system 302, a photoelectric converter 304, an image processing circuit 306, a monitor 308, and a memory 310. This distance image sensor 300 receives light (modulated light or pulsed light) that is irradiated from a light source device 320 toward the subject 330 and reflected from the surface of the subject 330, and acquires a distance image corresponding to the distance to the subject 330.

[0123] The optical system 302 consists of one or more lenses and has the role of forming an image of the image light (incident light) from the subject 330 onto the light-receiving surface (sensor part) of the photoelectric converter 304.

[0124] The photoelectric converter 304 is the photoelectric converter 100 described in the first to fourth embodiments, and has the function of generating a distance signal indicating the distance to the subject 330 based on the image light from the subject 330, and supplying the generated distance signal to the image processing circuit 306.

[0125] The image processing circuit 306 has the function of performing image processing to construct a distance image based on the distance signal supplied from the photoelectric converter 304.

[0126] The monitor 308 has the function of displaying the distance image (image data) obtained by the image processing in the image processing circuit 306. The memory 310 also has the function of storing (recording) the distance image (image data) obtained by the image processing in the image processing circuit 306.

[0127] Thus, according to this embodiment, by configuring a distance image sensor using the photoelectric conversion device of the first to fourth embodiments, it is possible to realize a distance image sensor capable of acquiring distance images containing more accurate distance information, in conjunction with improving the characteristics of the pixel 12.

[0128] [Seventh Embodiment] An endoscopic surgical system according to the seventh embodiment of the present invention will be described with reference to Figure 20. Figure 20 is a schematic diagram showing an example of the configuration of the endoscopic surgical system according to this embodiment. In this embodiment, the endoscopic surgical system will be described as an example of a photodetection system to which the photoelectric converter 100 described in the first to fourth embodiments is applied.

[0129] Figure 20 illustrates a surgeon (physician) 460 performing surgery on a patient 472 on a patient bed 470 using an endoscopic surgical system 400.

[0130] As shown in Figure 20, the endoscopic surgical system 400 of this embodiment may consist of an endoscope 410, surgical instruments 420, and a cart 430 equipped with various devices for endoscopic surgery. The cart 430 may be equipped with a Camera Control Unit (CCU) 432, a light source device 434, an input device 436, a treatment instrument control device 438, a display device 440, and the like.

[0131] The endoscope 410 comprises a barrel 412, the portion of which a predetermined length from the tip is inserted into the body cavity of the patient 472, and a camera head 414 connected to the base end of the barrel 412. Figure 20 illustrates the endoscope 410 configured as a so-called rigid endoscope having a rigid barrel 412, but the endoscope 410 may also be configured as a so-called flexible endoscope having a flexible barrel. The endoscope 410 is held in a movable state by an arm 416.

[0132] An opening into which an objective lens is fitted is provided at the tip of the endoscope tube 412. A light source device 434 is connected to the endoscope 410, and the light generated by the light source device 434 is guided to the tip of the endoscope tube by a light guide extending inside the endoscope tube 412, and is irradiated through the objective lens towards the object to be observed inside the body cavity of the patient 472. The endoscope 410 may be a straight-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0133] The camera head 414 contains an optical system and a photoelectric converter (not shown), and reflected light from the object being observed (observation light) is focused by the optical system into the photoelectric converter. The photoelectric converter converts the observation light into electrical signals, generating an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The photoelectric converter 100 described in the first embodiment can be used as the photoelectric converter. The image signal is transmitted to the CCU 432 as RAW data.

[0134] The CCU432 consists of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and other components, and comprehensively controls the operation of the endoscope 410 and the display device 440. Furthermore, the CCU432 receives an image signal from the camera head 414 and performs various image processing operations on that image signal, such as development processing (demosaic processing), to display the image based on that image signal.

[0135] The display device 440 displays an image based on an image signal that has been processed by the CCU 432, under control from the CCU 432.

[0136] The light source device 434 consists of a light source such as an LED (Light Emitting Diode) and supplies illumination light to the endoscope 410 when photographing the surgical area, etc.

[0137] The input device 436 is an input interface for the endoscopic surgical system 400. The user can input various types of information and instructions to the endoscopic surgical system 400 via the input device 436.

[0138] The treatment instrument control device 438 controls the driving of the energy treatment instrument 450 for purposes such as tissue cauterization, incision, or blood vessel sealing.

[0139] The light source device 434 that supplies illumination light to the endoscope 410 when photographing the surgical area can be composed of, for example, an LED, a laser light source, or a combination thereof. When the white light source is composed of a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so the white balance of the captured image can be adjusted in the light source device 434. In this case, it is also possible to capture images corresponding to each of the RGB colors in time-division by irradiating the observation target with laser light from each of the RGB laser light sources in time-division and controlling the drive of the image sensor of the camera head 414 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter on the image sensor.

[0140] Furthermore, the light source device 434 may be controlled to change the intensity of the light it outputs at predetermined time intervals. By controlling the drive of the image sensor of the camera head 414 in synchronization with the timing of the change in light intensity, images can be acquired in time-division order, and these images can be combined to generate high dynamic range images without so-called black crushing and white clipping.

[0141] Furthermore, the light source device 434 may be configured to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, the wavelength dependence of light absorption in body tissue is utilized. Specifically, by irradiating with narrowband light compared to the irradiation light used during normal observation (i.e., white light), predetermined tissues such as blood vessels on the surface of mucosa can be imaged with high contrast. Alternatively, in special light observation, fluorescence observation may be performed to obtain an image from fluorescence generated by irradiation with excitation light. In fluorescence observation, excitation light can be irradiated onto body tissue and fluorescence from the body tissue can be observed, or a reagent such as indocyanine green (ICG) can be injected into body tissue and excitation light corresponding to the fluorescence wavelength of the reagent can be irradiated onto the body tissue to obtain a fluorescence image. The light source device 434 may be configured to supply narrowband light and / or excitation light corresponding to such special light observation.

[0142] Thus, according to this embodiment, by configuring an endoscopic surgical system using the photoelectric conversion device of the first to fourth embodiments, an endoscopic surgical system capable of acquiring higher quality images can be realized.

[0143] [Eighth Embodiment] An optical detection system and mobile body according to the eighth embodiment of the present invention will be described with reference to Figures 21 to 23. Figure 21 is a schematic diagram showing an example of the configuration of a mobile body according to this embodiment. Figure 22 is a block diagram showing a schematic configuration of the optical detection system according to this embodiment. Figure 23 is a flowchart showing the operation of the optical detection system according to this embodiment. In this embodiment, an example of application to an in-vehicle camera is shown as an optical detection system to which the photoelectric converter 100 described in the first to fourth embodiments is applied.

[0144] Figure 21 is a schematic diagram showing an example of the configuration of a mobile body (vehicle system) according to this embodiment. Figure 21 shows the configuration of a vehicle 500 (automobile) as an example of a vehicle system incorporating a photodetection system to which the photoelectric converter according to the first to fourth embodiments is applied. Figure 21(a) is a schematic front view of the vehicle 500, Figure 21(b) is a schematic top view of the vehicle 500, and Figure 21(c) is a schematic rear view of the vehicle 500. The vehicle 500 is equipped with a pair of photoelectric converters 502 on its front. Here, the photoelectric converters 502 are the photoelectric converters 100 described in the first embodiment. The vehicle 500 also includes an integrated circuit 503, an alarm device 512, and a main control unit 513.

[0145] Figure 22 is a block diagram showing an example configuration of a photodetection system 501 mounted on a vehicle 500. The photodetection system 501 includes a photoelectric converter 502, an image preprocessing unit 515, an integrated circuit 503, and an optical system 514. The photoelectric converter 502 is the photoelectric converter 100 described in the first to fourth embodiments. The optical system 514 forms an optical image of the subject on the photoelectric converter 502. The photoelectric converter 502 converts the optical image of the subject formed by the optical system 514 into an electrical signal. The image preprocessing unit 515 performs predetermined signal processing on the signal output from the photoelectric converter 502. The functions of the image preprocessing unit 515 may be incorporated into the photoelectric converter 502. The photodetection system 501 is provided with at least two sets of the optical system 514, photoelectric converter 502, and image preprocessing unit 515, and the output from the image preprocessing unit 515 of each set is input to the integrated circuit 503.

[0146] The integrated circuit 503 is an integrated circuit for imaging system applications and includes an image processing unit 504, an optical distance measuring unit 506, a disparity calculation unit 507, an object recognition unit 508, and an anomaly detection unit 509. The image processing unit 504 processes the image signal output from the image preprocessing unit 515. For example, the image processing unit 504 performs image processing such as development and defect correction on the output signal from the image preprocessing unit 515. The image processing unit 504 includes a memory 505 for temporarily holding the image signal. The memory 505 may store, for example, the location of known defective pixels in the photoelectric converter 502.

[0147] The optical distance measuring unit 506 focuses on and measures the distance of the subject. The parallax calculation unit 507 calculates distance information from multiple image data (parallax images) acquired by multiple photoelectric converters 502. Each of the photoelectric converters 502 may be configured to acquire various information such as distance information. The object recognition unit 508 recognizes subjects such as cars, roads, signs, and people. When the anomaly detection unit 509 detects an anomaly in the photoelectric converter 502, it notifies the main control unit 513 of the anomaly.

[0148] The integrated circuit 503 may be implemented by specially designed hardware, by a software module, or by a combination of these. It may also be implemented by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or a combination of these.

[0149] The main control unit 513 coordinates and controls the operation of the light detection system 501, vehicle sensor 510, control unit 520, etc. Note that the vehicle 500 does not necessarily have to have the main control unit 513. In this case, the photoelectric converter 502, vehicle sensor 510, and control unit 520 send and receive control signals via a communication network. For example, the CAN standard may be applied to the transmission and reception of these control signals.

[0150] The integrated circuit 503 has the function of receiving control signals from the main control unit 513 or transmitting control signals and set values ​​to the photoelectric converter 502 via its own control unit.

[0151] The light detection system 501 is connected to the vehicle sensor 510 and can detect the vehicle's driving conditions, such as vehicle speed, yaw rate, and steering angle, as well as the external environment and the state of other vehicles and obstacles. The vehicle sensor 510 also serves as a distance information acquisition means for acquiring distance information to objects. Furthermore, the light detection system 501 is connected to the driver assistance control unit 511, which performs various driving assistance functions such as automatic steering, automatic cruising, and collision avoidance. In particular, regarding the collision judgment function, it determines whether a collision with another vehicle or obstacle has occurred and estimates a collision based on the detection results of the light detection system 501 and the vehicle sensor 510. This enables avoidance control when a collision is estimated and activation of safety devices in the event of a collision.

[0152] Furthermore, the light detection system 501 is also connected to a warning device 512 that issues a warning to the driver based on the judgment result of the collision judgment unit. For example, if the collision judgment unit determines that there is a high probability of collision, the main control unit 513 performs vehicle control to avoid a collision or mitigate damage by applying the brakes, releasing the accelerator, or suppressing engine output. The warning device 512 warns the user by sounding an alarm, displaying warning information on a display screen such as the car navigation system or instrument panel, or vibrating the seat belt or steering wheel.

[0153] In this embodiment, the light detection system 501 captures images of the area around the vehicle, for example, the front or rear. Figure 21(b) shows an example of the arrangement of the light detection system 501 when it captures images of the area in front of the vehicle.

[0154] As described above, the photoelectric converter 502 is positioned in front of the vehicle 500. Specifically, it is preferable for acquiring distance information between the vehicle 500 and the object being photographed and for determining the possibility of collision if the two photoelectric converters 502 are positioned symmetrically with respect to the axis of symmetry, considering the center line with respect to the vehicle 500's direction of movement or external shape (e.g., vehicle width). Furthermore, it is preferable that the photoelectric converter 502 is positioned so as not to obstruct the driver's field of view when the driver is visually observing the situation outside the vehicle 500 from the driver's seat. It is preferable that the warning device 512 is positioned so as to be easily visible to the driver.

[0155] Next, the fault detection operation of the photoelectric converter 502 in the photodetection system 501 will be explained using Figure 23. The fault detection operation of the photoelectric converter 502 can be performed according to steps S110 to S180 shown in Figure 23.

[0156] Step S110 is a step in which the photoelectric converter 502 is configured for startup. Specifically, settings for the operation of the photoelectric converter 502 are transmitted from outside the photodetection system 501 (e.g., the main control unit 513) or from inside the photodetection system 501, and the imaging operation and fault detection operation of the photoelectric converter 502 are started.

[0157] Next, in step S120, a pixel signal is acquired from the active pixels. Also, in step S130, an output value is acquired from a fault detection pixel provided for fault detection. This fault detection pixel, like the active pixels, is equipped with a photoelectric conversion element. A predetermined voltage is written to this photoelectric conversion element. The fault detection pixel outputs a signal corresponding to the voltage written to this photoelectric conversion element. Note that steps S120 and S130 may be reversed.

[0158] Next, in step S140, a determination is made between the expected output value of the fault-detection pixel and the actual output value from the fault-detection pixel. If the determination in step S140 shows that the expected output value and the actual output value match, the process proceeds to step S150, where it is determined that the imaging operation is functioning normally, and the process moves to step S160. In step S160, the pixel signals of the scanned row are transmitted to the memory 505 for temporary storage. After that, the process returns to step S120 and continues the fault detection operation. On the other hand, if the determination in step S140 shows that the expected output value and the actual output value do not match, the process proceeds to step S170. In step S170, it is determined that there is an abnormality in the imaging operation, and an alarm is sent to the main control unit 513 or the alarm device 512. The alarm device 512 displays that an abnormality has been detected on its display unit. Subsequently, in step S180, the photoelectric converter 502 is stopped, and the operation of the photodetection system 501 is terminated.

[0159] In this embodiment, an example is shown where the flowchart is looped every row, but the flowchart may be looped every multiple rows, or the fault detection operation may be performed every frame. The alarm in step S170 may be notified to an external party via a wireless network.

[0160] Furthermore, although this embodiment describes control to avoid collisions with other vehicles, it can also be applied to control that automatically follows other vehicles or control that automatically drives without deviating from the lane. Moreover, the light detection system 501 can be applied not only to vehicles such as the vehicle itself, but also to moving objects (mobile devices) such as ships, aircraft, or industrial robots. In addition, it can be applied not only to moving objects, but also to a wide range of devices that utilize object recognition, such as intelligent transportation systems (ITS).

[0161] [Ninth Embodiment] A photodetection system according to the ninth embodiment of the present invention will be described with reference to Figure 24. Figure 24 is a schematic diagram showing an example of the configuration of the photodetection system according to this embodiment. In this embodiment, an example of application to eyeglasses (smart glasses) will be described as a photodetection system to which the photoelectric converter 100 described in the first to fourth embodiments is applied.

[0162] Figure 24(a) shows eyeglasses 600 (smart glasses) relating to one application example. The eyeglasses 600 have lenses 601, a photoelectric converter 602, and a control device 603.

[0163] The photoelectric converter 602 is the photoelectric converter 100 described in the first to fourth embodiments and is provided on the lens 601. There may be one or more photoelectric converters 602. Furthermore, when using multiple photoelectric converters 602, multiple types of photoelectric converters 602 may be used in combination. The arrangement position of the photoelectric converter 602 is not limited to that shown in Figure 24(a). A display device (not shown) including a light-emitting device such as an OLED or LED may be provided on the back side of the lens 601.

[0164] The control device 603 functions as a power supply that provides power to the photoelectric converter 602 and the display device. The control device 603 also has a function to control the operation of the photoelectric converter 602 and the display device. The lens 601 is provided with an optical system for focusing light onto the photoelectric converter 602.

[0165] Figure 24(b) shows eyeglasses 610 (smart glasses) relating to another application example. The eyeglasses 610 have lenses 611 and a control device 612. The control device 612 may be equipped with a photoelectric converter (not shown) corresponding to a photoelectric converter 602 and a display device. The lenses 611 are provided with the photoelectric converter in the control device 612 and an optical system for projecting light from the display device, thereby projecting an image. The control device 612 functions as a power source that supplies power to the photoelectric converter and the display device, and also has a function to control the operation of the photoelectric converter and the display device.

[0166] The control device 612 may further include a gaze detection unit that detects the wearer's gaze. In this case, the control device 612 can be provided with an infrared light emitter, and the infrared light emitted from the infrared light emitter can be used for gaze detection. Specifically, the infrared light emitter emits infrared light towards the eyeball of the user who is gazing at the displayed image. An image capture unit having a light-receiving element detects the reflected light from the eyeball of the emitted infrared light, thereby obtaining an image of the eyeball. By having a reduction means that reduces the light from the infrared light emitter to the display unit in a planar view, the deterioration of image quality can be reduced.

[0167] The user's gaze towards a displayed image can be detected from an image of the eyeball obtained by imaging with infrared light. Any known method can be applied to gaze detection using the image of the eyeball. As an example, a gaze detection method based on the Purkinje image obtained by the reflection of the irradiated light from the cornea can be used. More specifically, gaze detection processing based on the pupil-corneal reflection method is performed. Using the pupil-corneal reflection method, the user's gaze is detected by calculating a gaze vector representing the orientation (rotation angle) of the eyeball based on the pupil image and the Purkinje image contained in the image of the eyeball.

[0168] The display device of this embodiment may include a photoelectric converter having a light-receiving element and be configured to control the displayed image based on the user's gaze information from the photoelectric converter. Specifically, the display device determines a first field of view area that the user is fixated on and a second field of view area other than the first field of view area, based on the gaze information. The first and second field of view areas may be determined by the control device of the display device or by an external control device. If an external control device determines them, this information is transmitted to the display device via communication. In the display area of ​​the display device, the display resolution of the first field of view area may be controlled to be higher than the display resolution of the second field of view area. In other words, the resolution of the second field of view area may be lower than the resolution of the first field of view area.

[0169] Furthermore, the display area may have a first display area and a second display area different from the first display area, and may be configured to determine the area with higher priority from the first display area and the second display area based on gaze information. The first display area and the second display area may be determined by the control device of the display device or by an external control device. If the external control device makes the determination, it is communicated to the display device via communication. The resolution of the high-priority area may be controlled to be higher than the resolution of the areas other than the high-priority area. In other words, the resolution of areas with relatively lower priority may be lower.

[0170] AI may be used to determine the first field of view area and the areas with higher priority. The AI ​​may be a model configured to estimate the angle of gaze and the distance to the target object at the end of the line of sight from the image of the eye, using the image of the eye and the direction the eye was actually looking in that image as training data. The AI ​​program may be installed in the display device, the photoelectric converter, or an external device. If installed in an external device, it will be transmitted to the display device via communication.

[0171] When display control is based on visual detection, this method is preferably applicable to smart glasses that further include a photoelectric converter for capturing images of the surrounding environment. The smart glasses can display the captured external information in real time.

[0172] [Modified Embodiment] The present invention is not limited to the embodiments described above and can be modified in various ways. For example, an example in which a part of the configuration of one embodiment is added to another embodiment, or in which a part of the configuration of another embodiment is replaced, is also an embodiment of the present invention.

[0173] Furthermore, the circuit configuration of the pixel 12 is not limited to the above embodiment. For example, a switch such as a transistor may be provided between the photoelectric conversion element 22 and the quench circuit 32, or between the photoelectric conversion element 22 and the signal processing unit 30, to control the electrical connection state between them. Alternatively, a switch such as a transistor may be provided between the node to which voltage VH is supplied and the quench circuit 32, and / or between the node to which voltage VL is supplied and the photoelectric conversion element 22, to control the electrical connection state between them. In addition, multiple photoelectric conversion elements 22 may be provided for a single pixel 12.

[0174] Furthermore, in the above embodiment, the circuit configuration of the pixel 12 extracts signal charge (electrons) from the cathode side while keeping the anode side of the APD at a fixed potential. However, it is also possible to configure the APD to extract signal charge (holes) from the anode side while keeping the cathode side of the APD at a fixed potential.

[0175] Furthermore, although the above embodiment shows a configuration in which a counter circuit is used as the processing circuit 36, a TDC (Time to Digital Converter) and memory may be used instead of the counter circuit. In this case, the generation timing of the pulse signal output from the waveform shaping circuit 34 is converted into a digital signal by the TDC. When measuring the timing of the pulse signal, the TDC is supplied with a control pulse pREF (reference signal) from the vertical scanning circuit unit 40 via the control line 14. The TDC uses the control pulse pREF as a reference and acquires the signal as a digital signal when the input timing of the signal output from each pixel 12 is set to a relative time.

[0176] It should be noted that the above embodiments are merely examples of how the present invention can be implemented, and the technical scope of the present invention should not be interpreted as being limited by them. In other words, the present invention can be implemented in various forms without departing from its technical concept or its main features.

[0177] The above-disclosed embodiments include the following configurations and methods. (Composition 1) A first semiconductor layer on which a photoelectric conversion element is provided, A second semiconductor layer having a first surface and a second surface opposite to the first surface, wherein an element electrically connected to the photoelectric conversion element is provided on the first surface, A through electrode provided in a through hole penetrating the second semiconductor layer, A fixed charge layer is provided in contact with the inner surface of the through hole, A first insulating layer is provided between the fixed charge layer and the through electrode, A second insulating layer made of an insulating material containing silicon and provided in contact with the second surface, A photoelectric conversion device characterized by having the following features. (Configuration 2) The first semiconductor layer is arranged to face the first surface. A photoelectric conversion device according to configuration 1, characterized by the features described above. (Composition 3) The first semiconductor layer is arranged to face the second surface. A photoelectric conversion device according to configuration 1, characterized by the features described above. (Composition 4) The device further comprises a third insulating layer made of an insulating material having a higher refractive index than the second insulating layer, The second insulating layer is disposed between the second semiconductor layer and the third insulating layer. A photoelectric conversion device according to configuration 3, characterized by the features described above. (Composition 5) The second semiconductor layer further comprises a first wiring structure layer disposed on the side of the first surface of the second semiconductor layer, The second semiconductor layer is electrically connected to the first semiconductor layer via the first wiring structure layer. A photoelectric conversion device according to configuration 2, characterized by the features described above. (Composition 6) The first wiring structure layer has a connecting member connected to the through electrode. The photoelectric conversion device according to configuration 5, characterized by the features described herein. (Composition 7) The second semiconductor layer further comprises a first wiring structure layer disposed on the second surface side of the second semiconductor layer, The second semiconductor layer is electrically connected to the first semiconductor layer via the first wiring structure layer. A photoelectric conversion device according to configuration 3 or 4, characterized by the above. (Composition 8) The second semiconductor layer further comprises a second wiring structure layer disposed between the third surface of the first semiconductor layer facing the second semiconductor layer and the first wiring structure layer, The first wiring structure layer and the second wiring structure layer are electrically connected by a metal joint between the metal wiring contained in the first wiring structure layer and the metal wiring contained in the second wiring structure layer. A photoelectric conversion device according to any one of configurations 5 to 7, characterized by the above. (Composition 9) The first semiconductor layer further comprises an optical structure layer disposed on the fourth surface opposite to the third surface, The photoelectric conversion element receives light incident through the optical structure layer. A photoelectric conversion device according to configuration 8, characterized by the above. (Composition 10) The second semiconductor layer further comprises a third wiring structure layer disposed on the second surface side of the second semiconductor layer. A photoelectric conversion device according to configuration 5 or 6, characterized by the above. (Composition 11) The second semiconductor layer further comprises a third wiring structure layer disposed on the side of the first surface of the second semiconductor layer. A photoelectric conversion device according to configuration 7, characterized by the features described above. (Composition 12) The third wiring structure layer has a connecting member connected to the through electrode. A photoelectric conversion device according to configuration 11, characterized by the features described above. (Composition 13) The through-hole penetrates the second semiconductor layer and the second insulating layer. A photoelectric conversion device according to any one of configurations 1 to 12, characterized by the above. (Composition 14) The opening width of the through hole on the second surface is wider than the opening width of the through hole on the first surface. A photoelectric conversion device according to any one of configurations 1 to 13, characterized by the above. (Composition 15) The thickness of the first insulating layer on the first surface is greater than the thickness of the first insulating layer on the second surface. A photoelectric conversion device according to any one of configurations 1 to 14, characterized by the above. (Composition 16) The second semiconductor layer has a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type different from the first conductivity type. The second insulating layer is in contact with the first semiconductor region and the second semiconductor region. A photoelectric conversion device according to any one of configurations 1 to 15, characterized by the above. (Composition 17) The second semiconductor layer has a third semiconductor region disposed around the through hole and a fourth semiconductor region disposed between the third semiconductor region and the first or second semiconductor region. The impurity concentration in the aforementioned fourth semiconductor region is lower than that in the aforementioned third semiconductor region. A photoelectric conversion device according to any one of configurations 1 to 16, characterized by the above. (Composition 18) The present invention further comprises a third semiconductor layer, the second semiconductor layer being positioned between the first semiconductor layer and the third semiconductor layer. A photoelectric conversion device according to any one of configurations 1 to 17, characterized by the above. (Composition 19) The fixed charge layer includes hafnium oxide, zirconium oxide, aluminum oxide, titanium oxide, or tantalum oxide. A photoelectric conversion device according to any one of configurations 1 to 18, characterized by the above. (Composition 20) The second insulating layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or silicon carbonitride. A photoelectric conversion device according to any one of configurations 1 to 19, characterized by the above. (Composition 21) A photoelectric conversion device according to any one of configurations 1 to 20, A signal processing device that processes the signal output from the aforementioned photoelectric converter and A light detection system characterized by having the following features. (Composition 22) The signal processing device generates a distance image representing distance information to the object based on the signal. The photodetection system according to configuration 21, characterized by the features described above. (Composition 23) It is a mobile object, A photoelectric conversion device according to any one of configurations 1 to 20, Distance information acquisition means that acquires distance information to an object from a parallax image based on a signal output from the aforementioned photoelectric converter, Control means for controlling the moving body based on the distance information A mobile body characterized by having the following features. [Explanation of symbols]

[0178] 100... Photoelectric converter 110...Sensor board 111... Semiconductor layer 121…Wiring structure layer 130,160… Circuit board 131,161… Semiconductor layer 137, 148, 152… Insulating layer 141, 151, 171… Wiring structure layers 139... Through hole 147...Fixed charge layer 149...Through electrode

Claims

1. A first semiconductor layer on which a photoelectric conversion element is provided, A second semiconductor layer having a first surface and a second surface opposite to the first surface, wherein an element electrically connected to the photoelectric conversion element is provided on the first surface, A through electrode provided in a through hole penetrating the second semiconductor layer, A fixed charge layer is provided in contact with the inner surface of the through hole, A first insulating layer is provided between the fixed charge layer and the through electrode, A second insulating layer made of an insulating material containing silicon and provided in contact with the second surface A photoelectric conversion device characterized by having the following features.

2. The first semiconductor layer is arranged to face the first surface. The photoelectric conversion device according to claim 1, characterized by the features described above.

3. The first semiconductor layer is arranged to face the second surface. The photoelectric conversion device according to claim 1, characterized by the features described above.

4. It further comprises a third insulating layer made of an insulating material having a higher refractive index than the second insulating layer, The second insulating layer is disposed between the second semiconductor layer and the third insulating layer. The photoelectric conversion device according to claim 3.

5. The second semiconductor layer further comprises a first wiring structure layer disposed on the first surface side of the second semiconductor layer, The second semiconductor layer is electrically connected to the first semiconductor layer via the first wiring structure layer. The photoelectric conversion device according to claim 2.

6. The first wiring structure layer has a connecting member connected to the through electrode. The photoelectric conversion device according to claim 5, characterized in that it is a photoelectric device.

7. The second semiconductor layer further comprises a first wiring structure layer disposed on the second surface side of the second semiconductor layer, The second semiconductor layer is electrically connected to the first semiconductor layer via the first wiring structure layer. The photoelectric conversion device according to claim 3.

8. The second wiring structure layer is further disposed between the third surface of the first semiconductor layer facing the second semiconductor layer and the first wiring structure layer, The first wiring structure layer and the second wiring structure layer are electrically connected by a metal joint between the metal wiring contained in the first wiring structure layer and the metal wiring contained in the second wiring structure layer. The photoelectric conversion device according to any one of claims 5 to 7.

9. The first semiconductor layer further comprises an optical structure layer disposed on the fourth surface opposite to the third surface, The photoelectric conversion element receives light incident through the optical structure layer. The photoelectric conversion device according to claim 8.

10. The second semiconductor layer further comprises a third wiring structure layer disposed on the second surface side of the second semiconductor layer. The photoelectric conversion device according to claim 5, characterized in that it is a photoelectric device.

11. The second semiconductor layer further comprises a third wiring structure layer disposed on the side of the first surface of the second semiconductor layer. The photoelectric conversion device according to claim 7.

12. The third wiring structure layer has a connecting member connected to the through electrode. The photoelectric conversion device according to claim 11, characterized in that it is a photoelectric conversion device.

13. The through-hole penetrates the second semiconductor layer and the second insulating layer. The photoelectric conversion device according to any one of claims 1 to 6.

14. The opening width of the through hole on the second surface is wider than the opening width of the through hole on the first surface. The photoelectric conversion device according to any one of claims 1 to 6.

15. The thickness of the first insulating layer on the first surface is greater than the thickness of the first insulating layer on the second surface. The photoelectric conversion device according to any one of claims 1 to 6.

16. The second semiconductor layer has a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type different from the first conductivity type. The second insulating layer is in contact with the first semiconductor region and the second semiconductor region. The photoelectric conversion device according to any one of claims 1 to 6.

17. The second semiconductor layer has a third semiconductor region disposed around the through hole and a fourth semiconductor region disposed between the third semiconductor region and the first or second semiconductor region. The impurity concentration in the fourth semiconductor region is lower than that in the third semiconductor region. The photoelectric conversion device according to claim 16, characterized in that it is a photoelectric conversion device.

18. The present invention further comprises a third semiconductor layer, the second semiconductor layer being positioned between the first semiconductor layer and the third semiconductor layer. The photoelectric conversion device according to any one of claims 1 to 6.

19. The fixed charge layer includes hafnium oxide, zirconium oxide, aluminum oxide, titanium oxide, or tantalum oxide. The photoelectric conversion device according to any one of claims 1 to 6.

20. The second insulating layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or silicon carbonitride. The photoelectric conversion device according to any one of claims 1 to 6.

21. A photoelectric conversion device according to any one of claims 1 to 6, A signal processing device that processes the signal output from the aforementioned photoelectric converter and A light detection system characterized by having the following features.

22. The signal processing device generates a distance image representing distance information to the object based on the signal. The light detection system according to claim 21, characterized in that it is as described above.

23. It is a mobile object, A photoelectric conversion device according to any one of claims 1 to 6, Distance information acquisition means that acquires distance information to an object from a parallax image based on a signal output from the aforementioned photoelectric converter, Control means for controlling the moving body based on the distance information A mobile body characterized by having the following features.

Images