Photoelectric conversion device and photoelectric conversion system

Abstract

To improve the breakdown voltage performance of a photoelectric conversion device.SOLUTION: A photoelectric conversion device has a semiconductor layer having an avalanche photodiode, and a wiring structure electrically connected with the semiconductor layer, and the photoelectric conversion device includes a pixel area having the avalanche photodiode, and a peripheral area located between the pixel area and an outer edge of the photoelectric conversion device, in plan view with respect to the boundary between the semiconductor layer and the wiring structure. The wiring structure includes a first wiring layer, a second wiring layer, and a third wiring layer. The third wiring layer is located between the first wiring layer and the second wiring layer. The first wiring layer includes, in the peripheral area, a first conductive part for transmitting an anode potential of the avalanche photodiode. The second wiring layer includes, in the peripheral area, a second conductive part for transmitting a second potential different from the anode potential. In plan view, the first conductive part and the second conductive part overlap each other.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] A photoelectric conversion device having an avalanche photodiode capable of detecting photons for each pixel has been proposed. Patent Document 1 describes a photoelectric conversion device formed by combining a sensor substrate having an avalanche photodiode with a circuit board for processing signals. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-201005 Summary of the Invention [Problem to be solved by the invention]

[0004] An operating voltage of about 20 to 30 V is applied to an avalanche photodiode. Depending on the configuration of the photoelectric conversion device, the transmission of such a high voltage may easily cause malfunction. One aspect of the present invention aims to provide a technique for improving the withstand voltage performance of a photoelectric conversion device. [Means for solving the problem]

[0005] In view of the above problems, there is provided a photoelectric conversion device having a semiconductor layer having an avalanche photodiode and an interconnection structure electrically connected to the semiconductor layer, wherein the photoelectric conversion device includes, in a plan view with respect to a boundary between the semiconductor layer and the interconnection structure, a pixel region having the avalanche photodiode and a peripheral region located between the pixel region and an outer edge of the photoelectric conversion device, the interconnection structure including a first interconnection layer, a second interconnection layer, and a third interconnection layer, the third interconnection layer being located between the first interconnection layer and the second interconnection layer, the first interconnection layer including, in the peripheral region, a first conductive portion for transmitting an anode potential of the avalanche photodiode, and the second interconnection layer including, in the peripheral region, a second conductive portion for transmitting a second potential different from the anode potential, and the first conductive portion and the second conductive portion overlap in the plan view. the semiconductor layer has a charge discharge portion in the peripheral region that collects charges in the semiconductor layer, the second conductive portion is connected to the charge discharge portion, and the third wiring layer does not include a conductive portion at a position where the first conductive portion and the second conductive portion overlap in the plan view. A photoelectric conversion device is provided. [Effects of the Invention]

[0006] By the above means, the voltage resistance performance of the photoelectric conversion device is improved. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a photoelectric conversion device according to some embodiments. [Figure 2] FIG. 3 is a schematic diagram of a PD substrate of a photoelectric conversion device according to some embodiments. [Figure 3] FIG. 3 is a schematic diagram of a circuit board of a photoelectric conversion device according to some embodiments. [Figure 4] 1 shows an example of the configuration of a pixel circuit of a photoelectric conversion device according to some embodiments. [Figure 5] FIG. 3 is a schematic diagram illustrating driving of pixel circuits of a photoelectric conversion device according to some embodiments. [Figure 6] 1 is a cross-sectional view of a photoelectric conversion device according to a first embodiment. [Figure 7] FIG. 1 is a plan view of a photoelectric conversion device according to a first embodiment. [Figure 8] 5A and 5B are schematic diagrams showing modified mesh shapes according to the first embodiment. [Figure 9]FIG. 10 is a cross-sectional view of a photoelectric conversion device according to a second embodiment. [Figure 10] FIG. 10 is a plan view of a photoelectric conversion device according to a second embodiment. [Figure 11] FIG. 10 is a schematic view showing a modified example of the conductive portion according to the second embodiment. [Figure 12] FIG. 10 is a cross-sectional view of a photoelectric conversion device according to a third embodiment. [Figure 13] FIG. 10 is a cross-sectional view of a photoelectric conversion device according to a fourth embodiment. [Figure 14] FIG. 10 is a plan view of a photoelectric conversion device according to a fifth embodiment. [Figure 15] FIG. 10 is a cross-sectional view of a photoelectric conversion device according to a reference example. [Figure 16] FIG. 10 is a plan view of a photoelectric conversion device according to a reference example. [Figure 17] FIG. 1 illustrates a photoelectric conversion system according to some embodiments. [Figure 18] FIG. 1 illustrates a photoelectric conversion system according to some embodiments. [Figure 19] FIG. 1 illustrates a photoelectric conversion system according to some embodiments. [Figure 20] FIG. 1 illustrates a photoelectric conversion system according to some embodiments. [Figure 21] FIG. 1 illustrates a photoelectric conversion system according to some embodiments. [Figure 22] FIG. 1 illustrates a photoelectric conversion system according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0009] In the following description, terms indicating specific directions or positions (e.g., "upper," "lower," "right," "left," and other terms including these terms) are used as needed. The use of these terms is for the purpose of facilitating understanding of the embodiments with reference to the drawings. The meanings of these terms do not limit the technical scope of the present disclosure.

[0010] In the following description, the anode of an avalanche photodiode (hereinafter referred to as APD) is set to a fixed potential, and a signal is extracted from the cathode. Therefore, a first conductivity type semiconductor region having majority carriers of charges of the same polarity as the signal charge is an N-type semiconductor region, and a second conductivity type semiconductor region having majority carriers of charges of a polarity opposite to that of the signal charge is a P-type semiconductor region. The embodiments described below are also applicable to cases where the cathode of the APD is set to a fixed potential and a signal is extracted from the anode. In this case, the first conductivity type semiconductor region having majority carriers of charges of the same polarity as the signal charge is a P-type semiconductor region, and the second conductivity type semiconductor region having majority carriers of charges of a polarity opposite to that of the signal charge is an N-type semiconductor region. While the following description focuses on a case where one node of the APD is set to a fixed potential, the potentials of both nodes may fluctuate.

[0011] In this specification, when the term "impurity concentration" is used simply, it means the net impurity concentration minus the amount compensated for by impurities of the opposite conductivity type. In other words, "impurity concentration" refers to the NET doping concentration. A region where the P-type doped impurity concentration is higher than the N-type doped impurity concentration is a P-type semiconductor region. Conversely, a region where the N-type doped impurity concentration is higher than the P-type doped impurity concentration is an N-type semiconductor region.

[0012] A configuration common to each embodiment of a photoelectric conversion device and a driving method thereof according to some embodiments will be described with reference to FIGS. 1 to 5. FIG. 1 is a diagram illustrating the configuration of a stacked photoelectric conversion device 100 according to an embodiment of the present disclosure. The photoelectric conversion device 100 is configured by stacking and electrically connecting two substrates, a sensor substrate 11 and a circuit substrate 21. The sensor substrate 11 has a first semiconductor layer having a photoelectric conversion element 102 (described later) and a first wiring structure. The circuit substrate 21 has a second semiconductor layer having circuits such as a signal processing unit 103 (described later) and a second wiring structure. The photoelectric conversion device 100 is a back-illuminated photoelectric conversion device that converts light incident on the photoelectric conversion element 102 from the side opposite the signal processing circuit.

[0013] In the following description, the sensor substrate 11 and the circuit substrate 21 are each a diced chip. However, these substrates are not limited to chips. For example, each substrate may be a wafer. Furthermore, each substrate may be stacked in the wafer state and then diced, or chips may be stacked and bonded after being cut into chips. The sensor substrate 11 has a pixel region 12 arranged thereon, and the circuit substrate 21 has a circuit region 22 arranged thereon that processes signals detected in the pixel region 12.

[0014] FIG. 2 is a diagram showing an example of the arrangement of the sensor substrate 11. Pixels 101, each having a photoelectric conversion element 102 including an APD, are arranged in a two-dimensional array in a planar view of the surface of the sensor substrate 11. The region in which these pixels 101 are arranged is the pixel region 12. The pixels 101 are typically pixels for forming an image. However, when the photoelectric conversion device 100 is used for TOF (Time of Flight), the pixels 101 do not necessarily need to form an image. In other words, the pixels 101 may be pixels for measuring the time and amount of light that arrives.

[0015] 3 is a configuration diagram of the circuit board 21. The circuit board 21 has a signal processing unit 103, a readout circuit 112, a control pulse generating unit 115, a horizontal scanning circuit unit 111, a vertical scanning circuit unit 110, and an output circuit 114. The circuit board 21 further has signal lines 113 and drive lines 116. The photoelectric conversion elements 102 in FIG. 2 and the signal processing unit 103 in FIG. 3 are electrically connected via connection wiring provided for each pixel.

[0016] The signal processing unit 103 processes signals based on the charges obtained by photoelectric conversion in the photoelectric conversion element 102 in Fig. 2. The vertical scanning circuit unit 110 receives control pulses supplied from a control pulse generation unit 115 and supplies the control pulses to each pixel 101 via drive lines 116. The vertical scanning circuit unit 110 is composed of logic circuits such as a shift register and an address decoder.

[0017] The signal output from the photoelectric conversion element 102 of the pixel 101 is processed by the signal processing unit 103. The signal processing unit 103 has a counter, a memory, etc. The signal output from the photoelectric conversion element 102 is held in the memory in a digital format.

[0018] In order to read out the digital signals from the memories of the pixels, the horizontal scanning circuit unit 111 inputs control pulses for sequentially selecting each column to the signal processing unit 103. For the selected column, a signal is output from the signal processing unit 103 of the pixel selected by the vertical scanning circuit unit 110 to the readout circuit 112 via a signal line 113. The signal output to the readout circuit 112 is output via an output circuit 114 to a recording unit or signal processing unit outside the photoelectric conversion device 100.

[0019] 2, the photoelectric conversion elements 102 in the pixel region 12 may be arranged one-dimensionally. The effects of the present disclosure can be obtained even when there is only one pixel 101, and the case where there is only one pixel 101 is also included in the present disclosure. The function of the signal processing unit 103 does not necessarily need to be provided for each photoelectric conversion element 102; for example, one signal processing unit 103 may be shared by multiple photoelectric conversion elements 102, and signal processing may be performed sequentially.

[0020] As shown in FIGS. 2 and 3 , a plurality of signal processing units 103 are arranged in a region overlapping the pixel region 12 in a planar view. A vertical scanning circuit unit 110, a horizontal scanning circuit unit 111, a readout circuit 112, an output circuit 114, and a control pulse generation unit 115 are arranged so as to overlap a region between the outer edge of the sensor substrate 11 and the outer edge of the pixel region 12 in a planar view. In other words, the sensor substrate 11 has a pixel region 12 and a non-pixel region arranged around the pixel region 12. The vertical scanning circuit unit 110, the horizontal scanning circuit unit 111, the readout circuit 112, the output circuit 114, and the control pulse generation unit 115 are arranged in a region overlapping the non-pixel region in a planar view. The arrangement of the signal lines 113, the readout circuit 112, and the output circuit 114 is not limited to the example shown in FIG. 3 . For example, the signal lines 113 may be arranged extending in the row direction, and the readout circuit 112 may be arranged at the end of the signal lines 113.

[0021] Fig. 4 is an example of a block diagram including the equivalent circuits of Fig. 2 and Fig. 3. As described with reference to Fig. 2, the photoelectric conversion element 102 having the APD 201 is provided on the sensor substrate 11, and the other circuit elements are provided on the circuit substrate 21.

[0022] The APD 201 generates charge pairs in response to incident light through photoelectric conversion. A voltage VL is supplied to the anode of the APD 201. The voltage VL supplied to the anode is sometimes called the anode potential. A voltage VH higher than the voltage VL supplied to the anode is supplied to the cathode of the APD 201. The voltage supplied to the cathode is sometimes called the cathode potential. A reverse bias voltage is supplied to the anode and cathode so that the APD 201 performs avalanche multiplication. With such a voltage supplied, the charges generated by the incident light undergo avalanche multiplication, generating an avalanche current.

[0023] When a reverse bias voltage is supplied, APDs can be operated in either Geiger mode, where the potential difference between the anode and cathode is greater than the breakdown voltage, or in linear mode, where the potential difference between the anode and cathode is close to or less than the breakdown voltage. APDs operating in Geiger mode are called SPADs (Single Photon Avalanche Diodes). For example, the voltage VL is -30V and the voltage VH is 1V. The APD201 can be operated in either linear mode or Geiger mode. In the case of a SPAD, the potential difference is larger than in a linear mode APD, resulting in a more pronounced effect on withstand voltage.

[0024] The quench element 202 is connected between the power supply line that supplies the voltage VH and the APD 201. The quench element 202 functions as a load circuit (quench circuit) during signal multiplication by avalanche multiplication, and suppresses avalanche multiplication by suppressing the voltage supplied to the APD 201 (quench operation). The quench element 202 also returns the voltage supplied to the APD 201 to voltage VH by passing a current equivalent to the voltage drop caused by the quench operation (recharge operation).

[0025] The signal processing unit 103 has a waveform shaping unit 210, a counter circuit 211, and a selection circuit 212. The waveform shaping unit 210 outputs a pulse signal obtained by shaping a change in the potential of the cathode of the APD 201 obtained when a photon is detected. For example, an inverter circuit is used as the waveform shaping unit 210. While FIG. 4 shows an example in which one inverter is used as the waveform shaping unit 210, a circuit in which multiple inverters are connected in series or another circuit having a waveform shaping effect may also be used.

[0026] The counter circuit 211 counts the pulse signal output from the waveform shaping unit 210 and holds the count value. In addition, in response to a control pulse being supplied via the drive line 213, the signal held in the counter circuit 211 is reset.

[0027] The selection circuit 212 switches between electrical connection and disconnection between the counter circuit 211 and the signal line 113 in response to a control pulse supplied from the vertical scanning circuit unit 110 in Fig. 3 via the drive line 214 in Fig. 4. The selection circuit 212 includes, for example, a buffer circuit for outputting a signal.

[0028] A switch such as a transistor may be disposed between the quench element 202 and the APD 201 or between the photoelectric conversion element 102 and the signal processing unit 103, and the electrical connection may be switched using this switch. Similarly, the supply of the voltage VH or the voltage VL to the photoelectric conversion element 102 may be electrically switched using a switch such as a transistor.

[0029] The example in FIG. 4 shows a configuration using a counter circuit 211. However, instead of the counter circuit 211, a time-to-digital converter (hereinafter referred to as TDC) and a memory may be used to acquire the pulse detection timing. In this case, the generation timing of the pulse signal output from the waveform shaping unit 210 is converted into a digital signal by the TDC. To measure the timing of the pulse signal, the TDC is supplied with a control pulse via a drive line from the vertical scanning circuit unit 110 in FIG. 1. The TDC acquires, as a digital signal, a signal obtained by converting the input timing of the signal output from each pixel via the waveform shaping unit 210 into a relative time based on this control pulse.

[0030] FIG. 5 is a diagram schematically illustrating the relationship between the operation of an APD and its output signal. In the explanation of FIG. 5, the input node of waveform shaping section 210 is represented as Node A, and the output node of waveform shaping section 210 is represented as Node B. Graph 501 in the upper part of FIG. 5 shows the waveform change at Node A. Specifically, the horizontal axis of graph 501 represents time, and the vertical axis of graph 501 represents the voltage at Node A. Graph 502 in the lower part of FIG. 5 shows the waveform change at Node B. Specifically, the horizontal axis of graph 502 represents time, and the vertical axis of graph 502 represents the voltage at Node B.

[0031] Between time t0 and time t1, a potential difference between voltage VH and voltage VL is applied to the APD 201. When a photon is incident on the APD 201 at time t1, avalanche multiplication occurs in the APD 201, an avalanche multiplication current flows through the quench element 202, and the voltage at Node A drops. The amount of voltage drop increases further, and at time t2 the voltage at Node A falls below the threshold. In response, the output of the waveform shaping unit 210 switches from low to high. Thereafter, avalanche multiplication in the APD 201 stops, and the voltage drop at Node A stops. Thereafter, a current flows from voltage VL to Node A to compensate for the voltage drop, and at time t3 the voltage at Node A exceeds the threshold. In response, the output of the waveform shaping unit 210 switches from high to low. In this way, the portion of the output waveform at Node A that falls below a certain threshold is waveform-shaped by waveform shaping section 210 and output as a signal at Node B.

[0032] First Embodiment Specific configuration examples of the photoelectric conversion device 100 according to the first embodiment will be described with reference to FIGS. 6 to 8. FIG. 6(a) shows a cross-sectional view of the photoelectric conversion device 100 taken along line A-A' in FIG. 7. FIG. 6(b) shows a cross-sectional view of the photoelectric conversion device 100 taken along line B-B' in FIG. 7. FIG. 7(a) shows a plan view of the wiring layer 621. FIG. 7(b) shows an enlarged view of a portion 700 in FIG. 7(a). FIG. 7(c) shows a plan view of the wiring layer 622. FIG. 7(d) shows an enlarged view of a portion 701 in FIG. 7(c). FIG. 7(e) shows a plan view of the wiring layer 623. FIG. 7(f) shows an enlarged view of a portion 702 in FIG. 7(e). FIG. 8 shows modified shapes of the conductive portion 711.

[0033] The cross-sectional structure of the photoelectric conversion device 100 will be described with reference to FIG. 6. As described above with reference to FIG. 1, the photoelectric conversion device 100 includes a sensor substrate 11 and a circuit substrate 21. The sensor substrate 11 includes a semiconductor layer 610 and a wiring structure 620. The wiring structure 620 is electrically connected to the semiconductor layer 610. The circuit substrate 21 includes a semiconductor layer 640 and a wiring structure 630. The wiring structure 630 is electrically connected to the semiconductor layer 640. The wiring structures 620 and 630 are joined and electrically connected to each other by a joining portion 605. The wiring structures 620 and 630 are located between the semiconductor layer 610 and the semiconductor layer 640. The lower surface of the semiconductor layer 610 and the upper surface of the wiring structure 620 are in contact with each other. Here, the lower surface of the semiconductor layer 610 refers to the surface located on the lower side in the cross-sectional view of FIG. 6. It is not intended to limit the use of the photoelectric conversion device 100 to a case where this surface of the semiconductor layer 610 faces downward (in the direction of gravity). The same applies to the upper and lower surfaces described below. The lower surface of the wiring structure 620 and the upper surface of the wiring structure 630 are bonded to each other. The lower surface of the wiring structure 630 and the upper surface of the semiconductor layer 640 are in contact with each other. The photoelectric conversion device 100 converts light incident from the upper surface of the semiconductor layer 610 into an electrical signal.

[0034] In the following description, the planar view of the boundary between the semiconductor layer 610 and the wiring structure 620 will simply be referred to as the planar view. When this boundary is a rough surface when viewed microscopically, the planar view will be defined based on the boundary when viewed macroscopically. When the upper and lower surfaces of the semiconductor layer 610 are parallel, the planar view of the boundary between the semiconductor layer 610 and the wiring structure 620 is equivalent to the planar view of the upper surface (i.e., the incident surface) of the semiconductor layer 610. Alternatively, the planar views of the lower surface of the wiring structure 620, the upper and lower surfaces of the wiring structure 630, and the upper and lower surfaces of the semiconductor layer 640 may each be equivalent to the planar view of the boundary between the semiconductor layer 610 and the wiring structure 620.

[0035] In the photoelectric conversion device 100, a region in which a plurality of photoelectric conversion elements 102 are arranged in a plan view is referred to as a pixel region 601. The pixel region 601 corresponds to the pixel region 12 in Figures 1 and 2. In the photoelectric conversion device 100, a region located between the pixel region 601 and an outer edge 603 of the photoelectric conversion device 100 in a plan view is referred to as a peripheral region 602.

[0036] In the pixel region 601, a plurality of photoelectric conversion elements 102 are arranged in a semiconductor layer 610. Two adjacent photoelectric conversion elements 102 are separated by an isolation region 612 formed in the semiconductor layer 610. The photoelectric conversion elements 102 and the peripheral region 602 are also separated by the isolation region 612. The isolation region 612 may have, for example, a DTI (Deep Trench Isolation) structure. The DTI structure has a structure in which an insulator is arranged in a trench formed in the semiconductor layer 610. The DTI structure may also be configured with a conductor or a light shield arranged in the trench, and an insulator arranged between the conductor or the light shield and the trench.

[0037] The photoelectric conversion element 102 is composed of a plurality of impurity semiconductor regions formed in the semiconductor layer 610. Specifically, the photoelectric conversion element 102 is composed of semiconductor regions 611 and 613 to 617. The semiconductor region 617 faces the lower surface of the semiconductor layer 610. The semiconductor region 617 is N-type. The semiconductor region 616 surrounds the periphery of the semiconductor region 617. The semiconductor region 616 is N-type. The concentration of the semiconductor region 617 may be higher than the concentration of the semiconductor region 616. The semiconductor region 615 is located on the semiconductor region 616. The semiconductor region 615 is P-type. The semiconductor region 614 is located on the semiconductor region 615. The semiconductor region 614 is N-type. The semiconductor region 611 is located on the semiconductor region 613. The semiconductor region 614 is P-type. The semiconductor region 613 surrounds the sides of the semiconductor regions 615 and 614. The semiconductor region 613 is a P-type region.

[0038] A cathode potential is supplied to the semiconductor region 617. An anode potential is supplied to the semiconductor region 613. The anode potential supplied to the semiconductor region 613 is also transmitted to the semiconductor regions 611 and 615. The area between the semiconductor region 615 and the semiconductor region 617 can also be called an avalanche region where avalanche multiplication occurs.

[0039] The semiconductor layer 610 has a charge discharging unit 650 in the peripheral region 602. The charge discharging unit 650 is composed of semiconductor regions 651 and 652. The semiconductor region 651 faces the lower surface of the semiconductor layer 610. The semiconductor region 651 is N-type. The semiconductor region 652 surrounds the periphery of the semiconductor region 651. The semiconductor region 652 is N-type. The concentration of the semiconductor region 651 may be higher than the concentration of the semiconductor region 652. The semiconductor region 651 may have the same configuration (e.g., impurity concentration and size) as the semiconductor region 617. The semiconductor region 652 may have the same configuration (e.g., impurity concentration and size) as the semiconductor region 616. The P-type semiconductor region 611 formed in the pixel region 601 extends to the peripheral region 602 and overlaps with the charge discharging unit 650 in a planar view.

[0040] A predetermined potential is supplied to the semiconductor region 651. The potential supplied to the semiconductor region 651 may be equal to the cathode potential of the APD of the photoelectric conversion element 102 or equal to ground potential. Alternatively, a predetermined potential is supplied to the semiconductor region 651. The potential supplied to the semiconductor region 651 may be another potential within a range with the cathode potential of the APD at one end and the ground potential at the center. For example, if the cathode potential of the APD is 1.1 V and the ground potential is 0 V, a potential within a range of −1.1 V to 1.1 V may be supplied to the semiconductor region 651. By supplying such a potential, the charge discharging unit 650 collects charges (e.g., electrons) generated in the semiconductor layer 610 in the peripheral region 602 and discharges them to the outside of the semiconductor layer 610. The semiconductor layer 610 further includes a light-shielding layer 618. The light-shielding layer 618 overlaps the charge discharging unit 650 in a planar view.

[0041] The wiring structure 620 has multiple wiring layers in an interlayer insulating layer 624. In the example of FIG. 6, the wiring structure 620 has three wiring layers 621 to 623. Of the multiple wiring layers included in the wiring structure 620, the wiring layer 621 is closest to the semiconductor layer 610, the wiring layer 622 is second closest to the semiconductor layer 610, and the wiring layer 623 is third closest to the semiconductor layer 610. In other words, the wiring structure 620 does not include any other wiring layer between the wiring layer 621 and the semiconductor layer 610. Furthermore, the wiring layer 622 is located between the wiring layer 621 and the wiring layer 623. The wiring layer 621 is located between the wiring layer 622 and the semiconductor layer 610.

[0042] A portion of the conductive portion included in the wiring layer 623 is exposed to the outside of the photoelectric conversion device 100 through an opening 606. This exposed portion becomes a pad 608. The pad 608 faces the outside of the photoelectric conversion device 100. The pad 608 may be used to connect a wire. A portion of the conductive portion included in the wiring layer 623 is exposed to the outside of the photoelectric conversion device 100 through an opening 607. This exposed portion becomes a pad 609. The pad 609 faces the outside of the photoelectric conversion device 100. The pad 609 may be used to connect a wire.

[0043] The wiring structure 620 and the wiring structure 630 are connected to each other by a plurality of connecting portions 605. The connecting portion 605 may be formed by connecting (bonding) a connecting member formed on the sensor substrate 11 to a connecting member formed on the circuit board 21. The connecting portion 605 may electrically connect the conductive portion of the wiring structure 620 to the conductive portion of the wiring structure 630 to each other. Furthermore, some of the plurality of connecting portions 605 may not be used to electrically connect the conductive portion of the wiring structure 620 to the conductive portion of the wiring structure 630 to each other, but may be used to increase the bonding strength between the wiring structure 620 and the wiring structure 630.

[0044] An example of the configuration of each of the wiring layers 621 to 623 will be described with reference to Fig. 7. An example of the configuration of the wiring layer 621 will be described with reference to Fig. 7(a) and Fig. 7(b). Fig. 7(b) is an enlarged view of a portion 700 in Fig. 7(a).

[0045] The wiring layer 621 has conductive portions 711 to 713 having different roles. The conductive portion 711 is disposed in the peripheral region 602. The conductive portion 711 has a role of transmitting a potential supplied to the charge discharging portion 650. The conductive portion 711 is formed of, for example, a material mainly composed of copper. The conductive portion 711 surrounds the pixel region 601 in a planar view. Specifically, as shown in FIG. 7(a), the conductive portion 711 may surround the entire pixel region 601 in a planar view. The conductive portion 711 includes a mesh-shaped portion. In the example of FIG. 7(a), the entire conductive portion 711 is mesh-shaped. In the mesh-shaped portion, the openings are not limited to rectangular shapes and may be circular or other polygonal shapes. Alternatively, only a portion of the conductive portion 711 may be mesh-shaped. In the example of FIG. 7(a), the conductive portion 711 is a single conductive member. Alternatively, the conductive portion 711 may be divided into multiple conductive members.

[0046] The conductive portion 712 is disposed in the pixel region 601. The outer portion of the conductive portion 712 extends beyond the boundary between the pixel region 601 and the peripheral region 602 and into the peripheral region 602. The conductive portion 712 serves to transmit the anode potential of the APD. The conductive portion 712 is formed, for example, of a material primarily composed of copper. The conductive portion 712 includes a mesh-like portion. The openings in the mesh-like portion are not limited to rectangular shapes and may be circular or other polygonal shapes. In the example of FIG. 7( a), the inner portion of the conductive portion 712 is mesh-like, and no openings are formed near the outer edge of the conductive portion 712. Alternatively, the entire conductive portion 712 may be mesh-like. In the example of FIG. 7( a), the conductive portion 712 is a single conductive member. Alternatively, the conductive portion 712 may be divided into multiple conductive members.

[0047] The conductive portion 713 is disposed in the pixel region 601. The conductive portion 713 serves to transmit the cathode potential of the APD. The conductive portion 713 is formed of, for example, a material mainly composed of copper. The wiring layer 621 has a plurality of conductive portions 713 corresponding to a plurality of photoelectric conversion elements 102. The photoelectric conversion elements 102 may correspond one-to-one to the plurality of conductive portions 713. Each conductive portion 713 is located inside an opening 715 formed in the conductive portion 712. In a plan view, the outer edge of the conductive portion 713 may be circular, rectangular, or a polygon with five or more sides (for example, an octagon).

[0048] As described above, the conductive portions 711 to 713 have different roles from one another. Therefore, the conductive portions 711 to 713 are electrically isolated from one another. Furthermore, the conductive portions 711 to 713 are spaced apart from one another.

[0049] Next, the mesh size of the conductive portions 711 and 712 will be described. A mesh is formed in the conductive portion 711 by regularly forming a plurality of openings 714. The width of the opening 714 is defined as D6. When the opening 714 is square, the length of one side of the opening 714 is defined as D6. When the opening 714 is rectangular, the average of the long and short sides may be defined as D6, or either the long or short side may be defined as D6. When the opening 714 has a shape other than rectangular, the average of the minimum and maximum distances of the orthogonal projection of the opening 714 may be defined as D6, or this minimum or maximum distance may be defined as D6. The same applies to the widths of the other openings described below. The distance between two adjacent openings 714 among the plurality of openings 714 is defined as D7. In this case, D6 + D7 represents the mesh pitch of the conductive portion 711. The distance between the outer edge of the conductive portion 711 and the plurality of openings 714 is defined as D5.

[0050] A mesh is formed in the conductive portion 712 by forming a plurality of openings 715 at regular intervals. The width of the openings 715 is defined as D2. The distance between two adjacent openings 715 among the plurality of openings 715 is defined as D1. In this case, D1+D2 represents the mesh pitch of the conductive portion 712. The distance between the outer edge of the conductive portion 712 and the plurality of openings 715 is defined as D3. Furthermore, the distance between the conductive portion 711 and the conductive portion 712 is defined as D4.

[0051] The mesh pitch of the conductive portion 711 (i.e., D6+D7) may be larger than the mesh pitch of the conductive portion 712 (i.e., D1+D2). That is, the mesh of the conductive portion 711 may be coarser than the mesh of the conductive portion 712. The mesh pitch of the conductive portion 712 may match the pitch of the photoelectric conversion elements 102. D1 and D2 may be equal to each other. That is, in the conductive portion 712, the mesh width and the opening width may be equal. D6 may be larger than D7. That is, in the conductive portion 711, the mesh width may be narrower than the opening width. D3 may be larger than D2. That is, in the conductive portion 712, the width of the outer periphery may be wider than the opening width. By widening the width of the outer periphery in this manner, it becomes possible to stably transmit the anode potential.

[0052] Specific size examples will be described below. D1 may be, for example, 1 μm to 5 μm. D2 may be, for example, 1 μm to 5 μm. D3 may be, for example, 15 μm to 25 μm. D4 may be, for example, 30 μm to 100 μm. D5 may be, for example, 15 μm to 25 μm. D6 may be, for example, 40 μm to 60 μm. D7 may be, for example, 15 μm to 25 μm.

[0053] Next, a configuration example of the wiring layer 622 will be described with reference to FIGS. 7(c) and 7(d). FIG. 7(d) is an enlarged view of a portion 701 in FIG. 7(c). The wiring layer 622 has conductive portions 721 to 723 that have different roles. The conductive portion 721 is disposed in the peripheral region 602. The conductive portion 721 has the role of transmitting the potential supplied to the charge discharging portion 650. The conductive portion 721 is formed of a material containing copper as a main component, for example. The wiring layer 622 has a total of four conductive portions 721, one at the center of each of the four sides of the photoelectric conversion device 100. However, the number and positions of the conductive portions 721 are not limited to this.

[0054] The conductive portion 722 is disposed in the pixel region 601. The outer portion of the conductive portion 722 extends beyond the boundary between the pixel region 601 and the peripheral region 602 and into the peripheral region 602. The conductive portion 722 serves to transmit the anode potential of the APD. The conductive portion 722 is formed, for example, of a material primarily composed of copper. The conductive portion 722 includes a mesh-like portion. In the mesh-like portion, the openings are not limited to rectangular shapes and may be circular or other polygonal shapes. In the example of FIG. 7( c), the inner portion of the conductive portion 722 is mesh-like, and no openings are formed near the outer edge of the conductive portion 722. Alternatively, the entire conductive portion 722 may be mesh-like. In the example of FIG. 7( c), the conductive portion 722 is a single conductive member. Alternatively, the conductive portion 722 may be divided into multiple conductive members.

[0055] The conductive portion 723 is disposed in the pixel region 601. The conductive portion 723 has a role of transmitting the cathode potential of the APD. The conductive portion 723 is formed of, for example, a material mainly composed of copper. The wiring layer 622 has a plurality of conductive portions 723 corresponding to a plurality of photoelectric conversion elements 102. The photoelectric conversion elements 102 and the plurality of conductive portions 723 may have a one-to-one correspondence. Each conductive portion 723 is located inside an opening 725 formed in the conductive portion 722. In a plan view, the outer edge of the conductive portion 723 may be circular, rectangular, or a polygon with five or more sides (for example, an octagon).

[0056] As described above, the conductive portions 721 to 723 have different roles. Therefore, the conductive portions 721 to 723 are electrically isolated from each other. Furthermore, the conductive portions 721 to 723 are spaced apart from each other.

[0057] Next, the mesh size of the conductive portion 722 will be described. A mesh is formed in the conductive portion 722 by regularly forming a plurality of openings 725. The width of the openings 725 is defined as D12. The distance between two adjacent openings 725 among the plurality of openings 725 is defined as D11. In this case, D11 + D12 represents the mesh pitch of the conductive portion 722. The distance between the outer edge of the conductive portion 722 and the plurality of openings 725 is defined as D13.

[0058] The mesh pitch of the conductive portion 722 may match the pitch of the photoelectric conversion elements 102. D11 and D12 may be equal to each other. That is, in the conductive portion 722, the mesh width and the opening width may be equal. D13 may be larger than D12. That is, in the conductive portion 722, the width of the outer periphery may be wider than the opening width.

[0059] The mesh of conductive portion 712 and the mesh of conductive portion 722 may be the same size. That is, D1=D11 and D2=D12 may be satisfied. In plan view, opening 715 and opening 725 may completely overlap (that is, the outer edges of the openings may coincide). Furthermore, in plan view, the outer edges of conductive portion 712 and conductive portion 722 may coincide.

[0060] Specific size examples will be described below. D11 may be, for example, 1 μm to 5 μm. D12 may be, for example, 1 μm to 5 μm. D13 may be, for example, 15 μm to 25 μm.

[0061] Next, with reference to FIGS. 7(e) and 7(f), a configuration example of the wiring layer 623 will be described. FIG. 7(f) is an enlarged view of a portion 702 in FIG. 7(e). The wiring layer 623 has conductive portions 731 to 733 having different roles. The conductive portion 731 is disposed in the peripheral region 602. The conductive portion 731 has a role of transmitting a potential supplied to the charge discharging portion 650. The conductive portion 731 includes a pad 609 facing the outside of the photoelectric conversion element 102. The conductive portion 731 is formed of, for example, aluminum. The wiring layer 623 has a total of four conductive portions 731, one at the center of each of the four sides of the photoelectric conversion element 102. However, the number and positions of the conductive portions 731 are not limited to this.

[0062] The conductive portion 732 is disposed in the pixel region 601 and the peripheral region 602. The conductive portion 732 serves to transmit the anode potential of the APD. The conductive portion 732 is formed of, for example, aluminum. The conductive portion 732 has an annular shape in the pixel region 601, and a portion of it extends to near the outer edge 603 of the photoelectric conversion element 102. The conductive portion 731 includes a pad 608 facing the outside of the photoelectric conversion element 102. In the example of FIG. 7( e), the conductive portion 732 is a single conductive member. Alternatively, the conductive portion 732 may be divided into multiple conductive members.

[0063] The conductive portion 733 is disposed in the pixel region 601. The conductive portion 733 serves to transmit the cathode potential of the APD. The cathode potential is supplied via a wiring layer located below the wiring structure 620 or via a wiring layer of the wiring structure 630. The conductive portion 733 is formed of, for example, a material mainly composed of copper. The wiring layer 623 has a plurality of conductive portions 733 corresponding to the plurality of photoelectric conversion elements 102. The plurality of photoelectric conversion elements 102 may correspond one-to-one to the plurality of conductive portions 733. Each conductive portion 733 is located inside an opening formed in the conductive portion 732. In a plan view, the outer edge of the conductive portion 733 may be circular, rectangular, or a polygon with five or more sides (e.g., an octagon). In addition, in a plan view, the conductive portion 733 may be larger than the conductive portion 713 or the conductive portion 723.

[0064] As described above, the conductive portions 731 to 733 have different roles. Therefore, the conductive portions 731 to 733 are electrically isolated from each other. Furthermore, the conductive portions 731 to 733 are spaced apart from each other.

[0065] Next, the mutual connection relationship between the wiring layers 621 to 623, the semiconductor layer 610, and the coupling section 605 will be described. The conductive sections 711, 721, and 731 all have the role of transmitting a potential supplied to the charge discharging section 650. The conductive sections 711, 721, and 731 are electrically connected to each other. Specifically, the conductive sections 711 and 721 overlap in a planar view and are connected to each other by plugs near the pad 609. In this specification, "overlapping" can include both partial overlapping and complete overlapping. The conductive sections 721 and 731 overlap in a planar view and are connected to each other by plugs near the pad 609. The conductive section 711 is connected to each of the plurality of charge discharging sections 650 (specifically, their semiconductor regions 651) by plugs.

[0066] When the photoelectric conversion device 100 is in use, a predetermined potential is supplied to the pad 609 from outside the photoelectric conversion element 102. This potential is transmitted by the conductive portions 711, 721, and 731 and supplied to the semiconductor region 651. As described above, this potential may be included in a range with the cathode potential of the APD at one end and the ground potential at the center.

[0067] The conductive portions 712, 722, and 732 all serve to transmit the anode potential of the APD. The conductive portions 712, 722, and 732 are electrically connected to one another. Specifically, the conductive portions 712 and 722 overlap in a planar view and are connected to one another by plugs near the boundary between the pixel region 601 and the peripheral region 602 and at multiple positions within the pixel region 601. The conductive portions 722 and 732 overlap in a planar view and are connected to one another by plugs near the boundary between the pixel region 601 and the peripheral region 602. The conductive portion 712 is connected to the semiconductor layer 610 (specifically, near the semiconductor region 613) by plugs at multiple positions within the pixel region.

[0068] When the photoelectric conversion device 100 is in use, an anode potential is supplied to the pad 608 from outside the photoelectric conversion element 102. The anode potential is transmitted by the conductive portions 712, 722, and 732 and supplied to the semiconductor layer 610.

[0069] The conductive portions 713, 723, and 733 all have the role of transmitting the cathode potential of the APD. The conductive portions 713, 723, and 733 arranged for the same photoelectric conversion element 102 are electrically connected to one another. Specifically, the conductive portion 713 and the conductive portion 723 overlap in a planar view and are connected to one another by a plug. The conductive portion 723 and the conductive portion 733 overlap in a planar view and are connected to one another by a plug. The conductive portion 733 and one coupling portion 605 overlap in a planar view and are connected to one another by a plug. The conductive portion 713 is connected to the semiconductor layer 610 (specifically, the semiconductor region 617) by a plug.

[0070] When the photoelectric conversion device 100 is in use, a cathode potential is supplied from the circuit board 21 to the sensor substrate 11. The cathode potential is transmitted by the conductive portions 713, 723, and 733 and supplied to the semiconductor region 617 of the semiconductor layer 610.

[0071] Next, the overlapping relationship of the conductive parts having different roles will be described. The overlapping relationships described below are all overlapping relationships in a plan view.

[0072] None of the conductive portions 712, 713, 721, 722, 723, 731, and 733 overlaps with conductive portions having different functions that are included in the wiring layers 621 to 623. The conductive portion 711 and the conductive portion 732 overlap each other in the peripheral region 602.

[0073] Next, the technical effects of this embodiment will be described. As described above, the conductive portion 711 and the conductive portion 732 overlap each other in the peripheral region 602. The conductive portion 711 is used to transmit a predetermined potential, and the conductive portion 732 is used to transmit an anode potential. The predetermined potential transmitted by the conductive portion 711 is, for example, another potential within a range with the cathode potential of the APD at one end and the ground potential at the center. The cathode potential is, for example, 1 V or 1.1 V. On the other hand, the cathode potential can be, for example, within a range from -20 V to -35 V, or a potential around that range. Therefore, the potential difference between the anode potential and the predetermined potential can be a value in the range of 15 V to 50 V.

[0074] Therefore, in this embodiment, the voltage resistance is improved at the position where the conductive portion 711 and the conductive portion 732 overlap each other. Specifically, the wiring layer 621 including the conductive portion 711 and the wiring layer 623 including the conductive portion 732 are not adjacent to each other, and the wiring layer 623 is located between them. Furthermore, the wiring layer 622 does not include a conductive portion at the position where the conductive portion 711 and the conductive portion 732 overlap. In this way, by separating the conductive portion 711 and the conductive portion 732, the effects of applying a high voltage can be reduced.

[0075] The technical effects of this embodiment will be described. Heat generated in the circuit board 21 is conducted through the wiring structure 620 and the wiring structure 630 toward the semiconductor layer 610. The mesh-shaped conductive portion 711 formed in the peripheral region 602 is connected to the pad 609 through other conductive portions and plugs. These conductive portions and plugs are made of metal and therefore have a higher thermoelectric coefficient than the interlayer insulating film 64. This allows heat to be dissipated from the semiconductor layer 610 to the outside of the photoelectric conversion device 100. The wiring structure 620 uses fewer wires than the wiring structure 630. Therefore, by forming the conductive portion 711 in the wiring structure 620, the area of ​​the conductive portion 711 can be increased, thereby further improving heat dissipation. Furthermore, the conductive portion 711 includes a mesh-shaped portion, which reduces the difference in density of the conductive portions in the wiring layer 621 between the pixel region 601 and the peripheral region 602. This reduction in density difference is advantageous for planarizing the wiring layer 621 during manufacturing.

[0076] Next, a modified example of this embodiment will be described. In the example of Fig. 6, the wiring structure 620 includes three wiring layers, but the number of wiring layers is not limited to this. When the wiring structure 620 includes four or more wiring layers, two or more wiring layers may be located between the wiring layer including the conductive portion 711 and the wiring layer including the conductive portion 732.

[0077] In the above example, the wiring layer 621 includes the conductive portion 711. Alternatively, the wiring layer 622 may include the conductive portion 711. Even in this case, the effect of improving heat dissipation can be obtained.

[0078] In the above example, a predetermined potential is supplied to the charge discharging unit 650 through the wiring layer 621, and an anode potential is supplied to the photoelectric conversion element 102 through the wiring layer 623. Alternatively, a predetermined potential may be supplied to the charge discharging unit 650 through the wiring layer 623, and an anode potential may be supplied to the photoelectric conversion element 102 through the wiring layer 621.

[0079] In the above example, the conductive portion 711 has a lattice-like mesh. Alternatively, the mesh may have another shape. Modified examples of the mesh shape will be described with reference to FIG. 8. In the example of FIG. 8(a), the openings 714 are arranged so that they are offset from one another in every row. In the example of FIG. 8(b), the openings 714 have a plurality of different sizes. Regardless of the shape, the conductive portion 711 can be mesh-shaped as long as it has a plurality of openings 714. Furthermore, the conductive portions 712 and 722 other than the conductive portion 711 may also have a mesh shape such as that shown in FIG. 8 or another shape.

[0080] Second Embodiment A specific configuration example of the photoelectric conversion device 100 according to the second embodiment will be described with reference to Figs. 9 to 11. The following description will focus on differences from the first embodiment. Portions for which description is omitted may be similar to those of the first embodiment. Figs. 9 and 10 correspond to Figs. 6 and 7 of the first embodiment, respectively. Fig. 11 shows a modified example of the shape of the conductive portion 1001.

[0081] The second embodiment differs from the first embodiment in that the wiring layer 622 further includes a conductive portion 1001. The conductive portion 1001 is disposed in the peripheral region 602. The conductive portion 1001 is formed of, for example, a material mainly composed of copper. The conductive portion 1001 surrounds the pixel region 601 in a planar view. Specifically, as shown in FIG. 10(a), the conductive portion 1001 may surround the entire pixel region 601 in a planar view. The conductive portion 1001 includes a mesh-like portion. In the example of FIG. 10(a), the entire conductive portion 1001 is mesh-shaped. Alternatively, only a portion of the conductive portion 1001 may be mesh-shaped. In the example of FIG. 10(a), the conductive portion 1001 is a single conductive member. Alternatively, the conductive portion 1001 may be divided into multiple conductive members.

[0082] The mesh size of the conductive portion 1001 will be described. A mesh is formed in the conductive portion 1001 by regularly forming a plurality of openings 1002. The width of the openings 1002 is defined as D16. The distance between two adjacent openings 1002 among the plurality of openings 1002 is defined as D17. In this case, D16 + D17 represents the mesh pitch of the conductive portion 1001. The distance between the outer edge of the conductive portion 1001 and the plurality of openings 1002 is defined as D15. The distance between the conductive portion 1001 and the conductive portion 722 is defined as D14.

[0083] The mesh pitch of conductive portion 1001 (i.e., D16+D17) may be larger than the mesh pitch of conductive portion 722 (i.e., D11+D12). That is, the mesh of conductive portion 1001 may be coarser than the mesh of conductive portion 722. Furthermore, the mesh pitch of conductive portion 1001 (i.e., D16+D17) may be smaller than the mesh pitch of conductive portion 711 (i.e., D6+D7). That is, the mesh of conductive portion 1001 may be finer than the mesh of conductive portion 711. D16 may be larger than D17. That is, in conductive portion 712, the mesh width may be narrower than the width of the opening. D13 may be larger than D12. That is, in conductive portion 712, the width of the outer periphery may be wider than the width of the opening. By widening the width of the outer periphery in this manner, it becomes possible to stably transmit the anode potential.

[0084] Specific size examples will be described below. D14 may be, for example, 20 μm to 80 μm. D15 may be, for example, 15 μm to 25 μm. D16 may be, for example, 30 μm to 50 μm. D17 may be, for example, 10 μm to 20 μm.

[0085] The conductive portion 1001 overlaps the conductive portion 711 and the conductive portion 732 in a plan view. The presence of the conductive portion 1001 in the wiring layer 622 reduces the difference in density of the conductive portions in the wiring layer 622 between the pixel region 601 and the peripheral region 602. Such a reduction in the density difference is advantageous for planarization of the wiring layer 622 during manufacturing.

[0086] The conductive portion 1001 does not have to be used for transmitting signals or supplying power. For example, the conductive portion 1001 does not have to be electrically connected to other conductive portions of the photoelectric conversion device 100. In this case, when the photoelectric conversion device 100 is in use, no potential is supplied to the conductive portion 1001, and the conductive portion 1001 is in a floating state. Alternatively, a predetermined potential may be supplied to the conductive portion 1001. To achieve the effect of improving the withstand voltage of the photoelectric conversion device 100, the potential supplied to the conductive portion 1001 may have a value close to the average value of the potential transmitted by the conductive portion 711 and the anode potential. Specifically, the potential supplied to the conductive portion 1001 may be included in a range having a width half the difference between the anode potential and the potential transmitted by the conductive portion 711, centered on the average value of the anode potential and the potential transmitted by the conductive portion 711. Specifically, when the anode potential is −20V and the potential transmitted by the conductive portion 711 is 1V, the potential supplied to the conductive portion 1001 may be in the range of −15.75V or more and −5.25V or less.

[0087] A modified example of the conductive portion 1001 will be described with reference to FIG. 11. FIG. 11(a) shows a plan view of the wiring layer 622. FIG. 11(b) shows an enlarged view of a portion 701 in FIG. 11(a). In this example, the wiring layer 622 has a plurality of conductive portions 1001 scattered in an island shape. The plurality of conductive portions 1001 are located in the peripheral region 602. The plurality of conductive portions 1001 are located on all four sides of the pixel region 601.

[0088] The width of one conductive portion 1001 is represented as D18. The distance between two adjacent conductive portions 1001 is represented as D19. The distance between the conductive portion 1001 and the conductive portion 722 is represented as D20. D18 may be, for example, 10 μm to 50 μm. D19 may be, for example, 10 μm to 50 μm. D20 may be, for example, 15 μm to 25 μm.

[0089] Third Embodiment A specific configuration example of the photoelectric conversion device 100 according to the third embodiment will be described with reference to Fig. 12. The following description will focus on differences from the first embodiment. Portions for which description is omitted may be the same as those in the first embodiment or the second embodiment. Fig. 12 corresponds to Fig. 6(a) of the first embodiment.

[0090] The third embodiment differs from the first embodiment in the configuration of the photoelectric conversion element 102. The photoelectric conversion element 102 is composed of semiconductor regions 1201 to 1205 in addition to the semiconductor regions 611 and 613 described in the first embodiment. The semiconductor region 1205 faces the lower surface of the semiconductor layer 610. The semiconductor region 1205 is N-type. The semiconductor region 1204 surrounds the side surfaces of the semiconductor region 1205. The semiconductor region 1204 is N-type. The concentration of the semiconductor region 1204 may be lower than the concentration of the semiconductor region 1205. The semiconductor region 1202 is located above the semiconductor region 1205. The semiconductor region 1202 is P-type. The semiconductor region 1203 surrounds the sides of the semiconductor regions 1202, 1204, and 1205. The semiconductor region 1203 may be N-type or P-type. The semiconductor region 1201 is located above the semiconductor regions 1202 and 1203. The semiconductor region 1201 is of P-type. The concentration of the semiconductor region 1201 may be lower than the concentration of the semiconductor region 1202. A cathode potential is supplied to the semiconductor region 1205. An anode potential is supplied to the semiconductor region 613. The anode potential supplied to the semiconductor region 613 is also transmitted to the semiconductor regions 1201 and 1202.

[0091] Furthermore, pad 608 is formed across two wiring layers. In other words, pad 608 is sufficiently thicker than the wiring layer located at the same height. This structure allows for miniaturization of the wiring layer while providing resistance to pressure when connecting to an external terminal.

[0092] <Fourth embodiment> A specific configuration example of the photoelectric conversion device 100 according to the fourth embodiment will be described with reference to Fig. 13 and Fig. 14. The following description will focus on differences from the first embodiment. Portions for which description is omitted may be the same as any of the first to third embodiments. Fig. 13 and Fig. 14 correspond to Fig. 6 and Fig. 7 of the first embodiment, respectively.

[0093] The fourth embodiment differs from the first embodiment in that the wiring layer 621, rather than the wiring layer 623, has the pads 608 and 609.

[0094] The wiring layer 621 has conductive portions 711 to 713 and 1411. The conductive portion 711 is similar to that in the first embodiment except that it includes a pad 609 and is made of aluminum. The conductive portions 712 and 713 are similar to those in the first embodiment except that they are made of aluminum.

[0095] The conductive portion 1411 is disposed in the peripheral region 602. The conductive portion 1411 serves to transmit the anode potential of the APD. The conductive portion 1411 is formed of, for example, aluminum. The conductive portion 1411 includes a pad 608. The wiring layer 621 has a total of four conductive portions 1411, two on each of the two sides of the photoelectric conversion device 100. However, the number and positions of the conductive portions 1411 are not limited to this.

[0096] The wiring layer 622 has conductive portions 722, 723, and 1421. The conductive portions 722 and 723 are the same as those in the first embodiment. The conductive portion 1421 has a role of transmitting the anode potential of the APD. The conductive portion 1421 is formed of, for example, a material containing copper as a main component. The wiring layer 622 has a total of four conductive portions 1421, two on each of the two sides of the photoelectric conversion device 100. However, the number and positions of the conductive portions 1421 are not limited to this.

[0097] The wiring layer 623 has conductive portions 732 and 733. The conductive portion 732 is similar to that in the first embodiment except that it does not include the pad 608 and is made of a material containing copper as a main component. The conductive portion 733 is similar to that in the first embodiment.

[0098] The conductive portions 732, 1411, and 1421 all have the role of transmitting the anode potential of the APD. The conductive portions 732, 1411, and 1421 are electrically connected to one another. Specifically, the conductive portions 1411 and 1421 overlap in a plan view and are connected to one another by a plug at a position overlapping the pad 608. The conductive portions 1421 and 732 overlap in a plan view and are connected to one another by a plug at a position overlapping the pad 608.

[0099] When the photoelectric conversion device 100 is in use, an anode potential is supplied to the pad 608 from outside the photoelectric conversion device 100. The anode potential is transmitted by the conductive portions 732, 1411, and 1421 and supplied to the semiconductor layer 610.

[0100] <Reference example> The configuration of a photoelectric conversion device according to a reference example will be described with reference to Fig. 15 and Fig. 16. The following description will focus on differences from the first embodiment. Fig. 15 and Fig. 16 correspond to Fig. 6 and Fig. 7 of the first embodiment, respectively. The photoelectric conversion device according to the reference example differs from the first embodiment in that it does not have conductive portions 711, 721, and 731, but the other parts may be the same.

[0101] <Modification> In the above-described embodiment, the photoelectric conversion device 100 is configured by coupling the sensor substrate 11 and the circuit substrate 12. Alternatively, the present disclosure may be applied to a photoelectric conversion device configured such that a wiring structure is connected to a single semiconductor layer on which a photoelectric conversion device and a processing circuit are formed.

[0102] <Other embodiments> A photoelectric conversion system incorporating the photoelectric conversion device exemplarily described through the above-described embodiments will now be described. An example of a photoelectric conversion system is shown in FIG. 17. The above-described photoelectric conversion device 100 is applicable to various photoelectric conversion systems. Examples of applicable photoelectric conversion systems include digital still cameras, digital camcorders, surveillance cameras, copiers, fax machines, mobile phones, vehicle-mounted cameras, and observation satellites. Furthermore, a camera module equipped with an optical system such as a lens and an imaging device is also included in the photoelectric conversion system.

[0103] The photoelectric conversion system is configured as, for example, an imaging system SYS. The imaging system SYS is a camera or an information terminal having a photographing function. The imaging device IS may further include a package PKG that houses the photoelectric conversion device 100 configured as an imaging device IC. The package PKG may include a base to which the imaging device IC is fixed, a lid facing the imaging device IC, and a connecting member that connects terminals provided on the base to terminals provided on the imaging device IC. The imaging device IS may also have multiple imaging device ICs mounted side by side in a common package PKG. The imaging device IS may also have imaging device ICs and other semiconductor device ICs mounted one on top of the other in a common package PKG.

[0104] The imaging system SYS may include an optical system OU that forms an image on the imaging device IS. The imaging system SYS may also include at least one of a control device CU that controls the imaging device IS, a processing device PU that processes signals obtained from the imaging device IS, and a display device DU that displays images obtained from the imaging device IS. The imaging system SYS may also include a storage device MU that stores images obtained from the imaging device IS.

[0105] FIG. 18(a) shows an example of an imaging system 1810 related to an in-vehicle camera. The imaging system 1810 includes a photoelectric conversion device 1811. The photoelectric conversion device 1811 may be any of the photoelectric conversion devices described in the above-described embodiments. The imaging system 1810 also includes an image processing unit 1812, which is a processing device that performs image processing on multiple pieces of image data acquired by the photoelectric conversion device 1811. The imaging system 1810 also includes a parallax acquisition unit 1813, which is a processing device that calculates parallax (phase difference between parallax images) from the multiple pieces of image data acquired by the photoelectric conversion device 1811. The imaging system 1810 also includes a distance acquisition unit 1814, which is a processing device that calculates the distance to an object based on the calculated parallax, and a collision determination unit 1815, which is a processing device that determines whether or not there is a possibility of a collision based on the calculated distance. Here, the parallax acquisition unit 1813 and the distance acquisition unit 1814 are examples of information acquisition units that acquire information such as distance information to an object. That is, the distance information is information related to parallax, defocus amount, distance to the object, etc. The collision determination unit 1815 may determine the possibility of a collision using any of this distance information. The various processing devices described above may be realized by dedicated hardware or by general-purpose hardware that performs calculations based on software modules. Furthermore, the processing devices may be realized by FPGA, ASIC, etc., or a combination thereof.

[0106] The imaging system 1810 is connected to a vehicle information acquisition device 1816 and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The imaging system 1810 is also connected to a control ECU 1817, which is a control device that outputs a control signal to generate a braking force on the vehicle based on the determination result of the collision determination unit 1815. In other words, the control ECU 1817 is an example of a mobile object control unit that controls a mobile object based on distance information. The imaging system 1810 is also connected to an alarm device 1818 that issues an alarm to the driver based on the determination result of the collision determination unit 1815. For example, if the determination result of the collision determination unit 1815 indicates a high possibility of a collision, the control ECU 1817 performs vehicle control to avoid the collision and mitigate damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. The alarm device 1818 warns the user by sounding an alarm, displaying alarm information on the screen of a car navigation system, etc., or vibrating the seat belt or steering wheel.

[0107] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are imaged by the imaging system 1810. Fig. 18(b) shows the imaging system 1810 when imaging the area in front of the vehicle (imaging range 1819). The vehicle information acquisition device 1816 sends an instruction to operate the imaging system 1810 to perform imaging.

[0108] In the above explanation, an example of control to prevent collision with other vehicles has been described, but the present invention can also be applied to control of automatic driving by following other vehicles, control of automatic driving to prevent deviation from a lane, etc. Furthermore, the imaging system is not limited to vehicles such as automobiles, but can be applied to moving bodies (transportation equipment) such as ships, aircraft, and industrial robots. The moving devices in moving bodies (transportation equipment) are various moving parts such as engines, motors, wheels, and propellers. In addition, the present invention can be applied not only to moving bodies, but also to a wide range of equipment that uses object recognition, such as intelligent transport systems (ITS).

[0109] 19 shows an example of the configuration of a photoelectric conversion system configured as a range image sensor. Range image sensor 1901 includes an optical system 1902, a photoelectric conversion device 1903, an image processing circuit 1904, a monitor 1905, and a memory 1906. Range image sensor 1901 can obtain a range image according to the distance to the subject by receiving light (modulated light or pulsed light) that is projected toward the subject from a light source device 1911 and reflected from the surface of the subject.

[0110] The optical system 1902 is configured with one or more lenses, and guides image light (incident light) from a subject to a photoelectric conversion device 1903, forming an image on a light receiving surface (sensor unit) of the photoelectric conversion device 1903. The photoelectric conversion device of each of the above-described embodiments is applied as the photoelectric conversion device 1903, and a distance signal indicating a distance determined from a light receiving signal output from the photoelectric conversion device 1903 is supplied to an image processing circuit 1904.

[0111] The image processing circuit 1904 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric conversion device 1903. The distance image (image data) obtained by this image processing is then supplied to a monitor 1905 for display, or supplied to a memory 1906 for storage (recording). By applying the above-described photoelectric conversion device to the distance image sensor 1901 configured in this way, the pixel characteristics are improved, making it possible to obtain, for example, a more accurate distance image.

[0112] Fig. 20 illustrates an example of the configuration of a photoelectric conversion system configured as an endoscopic surgery system. Fig. 20 illustrates a state in which an operator (doctor) 2050 is performing surgery on a patient 2052 on a patient bed 2051 using an endoscopic surgery system 2000. As illustrated, the endoscopic surgery system 2000 is composed of an endoscope 2001, a surgical tool 2002, and a cart 2010 on which various devices for endoscopic surgery are mounted.

[0113] The endoscope 2001 is composed of a lens barrel 2003, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 2052, and a camera head 2004 connected to the base end of the lens barrel 2003. In the example shown in the figure, the endoscope 2001 is configured as a so-called rigid scope having a rigid lens barrel 2003, but the endoscope 2001 may also be configured as a so-called flexible scope having a flexible lens barrel.

[0114] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 2003. A light source device 2012 is connected to the endoscope 2001, and light generated by the light source device 2012 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 2003, and is irradiated via the objective lens towards an observation target inside the body cavity of the patient 2052. The endoscope 2001 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0115] An optical system and a photoelectric conversion device are provided inside the camera head 2004, and light reflected from an observation object (observation light) is focused onto the photoelectric conversion device by the optical system. The observation light is photoelectrically converted by the photoelectric conversion device to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observation image. The photoelectric conversion device may be any of the photoelectric conversion devices described in the above-described embodiments. The image signal is sent to a camera control unit (CCU) 2011 as RAW data.

[0116] The CCU 2011 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 2001 and the display device 2015. Furthermore, the CCU 2011 receives an image signal from the camera head 2004 and performs various image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0117] The display device 2015, under the control of the CCU 2011, displays an image based on an image signal that has been subjected to image processing by the CCU 2011. The light source device 2012 is composed of a light source such as an LED (Light Emitting Diode), and supplies irradiating light to the endoscope 2001 when photographing an area to be operated on, etc. The input device 2013 is an input interface for the endoscopic surgery system 2000. A user can input various information and instructions to the endoscopic surgery system 2000 via the input device 2013. The treatment tool control device 2014 controls the driving of a surgical tool 2002 (e.g., an energy treatment tool) for cauterizing tissue, incising, sealing blood vessels, etc.

[0118] The light source device 2012 that supplies illumination light to the endoscope 2001 when photographing the surgical site can be configured from a white light source configured from, for example, an LED, a laser light source, or a combination of these. When the white light source is configured from a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, making it possible to adjust the white balance of the captured image in the light source device 2012. In this case, it is also possible to capture images corresponding to each RGB color in a time-division manner by irradiating the object of observation with laser light from each RGB laser light source in a time-division manner and controlling the drive of the image sensor of the camera head 2004 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter to the image sensor.

[0119] Furthermore, the light source device 2012 may be controlled to change the intensity of light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 2004 in synchronization with the timing of the change in the light intensity to acquire images in a time-division manner and combining the images, it is possible to generate an image with a high dynamic range that is free from so-called blocked-up shadows and blown-out highlights.

[0120] The light source device 2012 may also be configured to supply light in a predetermined wavelength band corresponding to special light observation. Special light observation utilizes, for example, the wavelength dependency of light absorption in body tissue. Specifically, by irradiating light with a narrower band than the light (i.e., white light) used in normal observation, a specific tissue, such as blood vessels on the surface of the mucosa, can be photographed with high contrast. Alternatively, special light observation may involve fluorescence observation, in which an image is obtained using fluorescence generated by irradiating excitation light. Fluorescence observation can involve irradiating excitation light onto a body tissue and observing the fluorescence from the body tissue, or by locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the body tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 2012 may be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0121] FIG. 21(a) illustrates an example of the configuration of a photoelectric conversion system configured as glasses 2100 (smart glasses). The glasses 2100 have a photoelectric conversion device 2102 to which the photoelectric conversion device 100 is applied. The photoelectric conversion device 2102 is the photoelectric conversion device described in each of the above embodiments. A display device including a light-emitting device such as an OLED or LED may be provided on the back side of the lens 2101. The photoelectric conversion device 2102 may be one or more. A combination of multiple types of photoelectric conversion devices may also be used. The arrangement position of the photoelectric conversion device 2102 is not limited to that shown in FIG. 21(a).

[0122] The glasses 2100 further include a control device 2103. The control device 2103 functions as a power source that supplies power to the photoelectric conversion device 2102 and the display device. The control device 2103 also controls the operations of the photoelectric conversion device 2102 and the display device. The lens 2101 is formed with an optical system for focusing light onto the photoelectric conversion device 2102.

[0123] FIG. 21(b) illustrates the configuration of a photoelectric conversion system configured as glasses 2110 (smart glasses). The glasses 2110 include a control device 2112, which is equipped with a photoelectric conversion device corresponding to the photoelectric conversion device 2102 and a display device. A lens 2111 includes a photoelectric conversion device in the control device 2112 and an optical system for projecting light emitted from the display device, and an image is projected onto the lens 2111. The control device 2112 functions as a power source that supplies power to the photoelectric conversion device and the display device, and controls the operation of the photoelectric conversion device and the display device. The control device may include a gaze detection unit that detects the gaze of the wearer. Infrared light may be used to detect the gaze. The infrared light emitter emits infrared light toward the eyeball of a user gazing at a displayed image. An imaging unit having a light receiving element detects the emitted infrared light reflected from the eyeball, thereby obtaining an image of the eyeball. By providing a reduction means for reducing the amount of light from the infrared light emitting section to the display section in a plan view, degradation of image quality is reduced.

[0124] The user's line of sight with respect to the displayed image is detected from an image of the eyeball obtained by capturing infrared light. Any known method can be applied to gaze detection using an image of the eyeball. As an example, a gaze detection method based on a Purkinje image formed by reflection of irradiated light on the cornea can be used. More specifically, gaze detection processing is performed based on the pupil-corneal reflex method. Using the pupil-corneal reflex method, a gaze vector representing the direction (rotation angle) of the eyeball is calculated based on the image of the pupil and the Purkinje image contained in the image of the eyeball, thereby detecting the user's gaze.

[0125] The display device of this embodiment may have a photoelectric conversion device having a light receiving element, and may control the image displayed on the display device based on information on the user's line of sight from the photoelectric conversion device.

[0126] Specifically, the display device determines a first field of view area where the user gazes and a second field of view area other than the first field of view area based on the line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the display device, or may be determined by an external control device and received. 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 that of the first field of view area.

[0127] The display area may include a first display area and a second display area different from the first display area, and a high-priority area may be determined from the first display area and the second display area based on line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the display device, or may be determined by an external control device and received. The resolution of the high-priority area may be controlled to be higher than the resolution of areas other than the high-priority area. In other words, the resolution of an area with a relatively low priority may be lowered.

[0128] Note that AI may be used to determine the first field of view area and areas with high priority. The AI ​​may be a model configured to estimate the angle of gaze and the distance to an object in the line of sight from an image of the eyeball, using as training data an image of the eyeball and the direction in which the eyeball in the image was actually looking. The AI ​​program may be included in the display device, the photoelectric conversion device, or an external device. If included in an external device, it is transmitted to the display device via communication.

[0129] When display control is performed based on visual recognition detection, the present invention is preferably applied to smart glasses that further include a photoelectric conversion device for capturing images of the outside world. The smart glasses can display captured external information in real time.

[0130] The photoelectric conversion device 100 of the above embodiment may be applied to electronic devices such as smartphones and tablets, as exemplified below. Fig. 22 is a diagram showing an example of the appearance of an electronic device 2200 equipped with the photoelectric conversion device 100 configured as a solid-state imaging device. Fig. 22(a) shows the front side of the electronic device 2200, and Fig. 22(b) shows the back side of the electronic device 2200.

[0131] 22(a), a display 2201 for displaying an image is disposed in the center of the surface of the electronic device 2200. Then, along the upper side of the surface of the electronic device 2200, front cameras 2202 and 2205 using the photoelectric conversion device 100, an IR light source 2203 for emitting infrared light, and a visible light source 2204 for emitting visible light are disposed.

[0132] Also, as shown in FIG. 22(b), along the upper edge of the back of the electronic device 2200, rear cameras 2206 and 2209 using the photoelectric conversion device 100, an IR light source 2207 that emits infrared light, and a visible light source 2208 that emits visible light are arranged.

[0133] In the electronic device 2200 configured as described above, by applying the above-described photoelectric conversion device 100, for example, it is possible to capture images with higher sensitivity. The photoelectric conversion device 100 can also be applied to other electronic devices, such as infrared sensors, distance measurement sensors using active infrared light sources, security cameras, and personal or biometric authentication cameras. This can improve the sensitivity and performance of these electronic devices. Furthermore, it is possible to achieve low power consumption of the system by reducing the power consumption of the light source.

[0134] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0135] 11 sensor substrate, 12 circuit board, 100 photoelectric conversion device, 610 semiconductor layer, 620 wiring structure

Claims

1. A photoelectric conversion device having a semiconductor layer having an avalanche photodiode and a wiring structure electrically connected to the semiconductor layer, The photoelectric conversion device has, in a plan view with respect to the boundary between the semiconductor layer and the wiring structure, a pixel region having the avalanche photodiode; a peripheral region located between the pixel region and an outer edge of the photoelectric conversion device, the wiring structure includes a first wiring layer, a second wiring layer, and a third wiring layer; the third wiring layer is located between the first wiring layer and the second wiring layer, the first wiring layer includes, in the peripheral region, a first conductive portion for transmitting an anode potential of the avalanche photodiode; the second wiring layer includes a second conductive portion for transmitting a second potential different from the anode potential in the peripheral region; In the plan view, the first conductive portion and the second conductive portion overlap each other, the semiconductor layer has a charge drain portion in the peripheral region that collects charges in the semiconductor layer, the second conductive portion is connected to the charge discharging portion, The photoelectric conversion device, wherein the third wiring layer does not include a conductive portion at a position where the first conductive portion and the second conductive portion overlap in the plan view.

2. The photoelectric conversion device according to claim 1 , wherein the second wiring layer is located between the third wiring layer and the semiconductor layer.

3. The photoelectric conversion device according to claim 1 , wherein the wiring structure does not include another wiring layer between the second wiring layer and the semiconductor layer.

4. 4. The photoelectric conversion device according to claim 1, wherein the second potential is included in a range having a cathode potential of the avalanche photodiode at one end and a ground potential at the center.

5. 5. The photoelectric conversion device according to claim 4, wherein the second potential is equal to a cathode potential of the avalanche photodiode.

6. The photoelectric conversion device according to claim 4 , wherein the second potential is equal to a ground potential.

7. 7. The photoelectric conversion device according to claim 1, wherein a potential difference between the anode potential and the second potential is 15V or more and 50V or less.

8. The photoelectric conversion device according to claim 1 , wherein the third wiring layer includes a third conductive portion that overlaps the first conductive portion and the second conductive portion in the plan view.

9. The photoelectric conversion device according to claim 8 , wherein no potential is supplied to the third conductive portion.

10. 9. The photoelectric conversion device according to claim 8, wherein a third potential is supplied to the third conductive portion, the third potential being included in a range having a width half the difference between the anode potential and the second potential and centered on the average value of the anode potential and the second potential.

11. The photoelectric conversion device according to claim 1 , wherein the second conductive portion includes a mesh-like portion.

12. The photoelectric conversion device according to claim 1 , wherein the first wiring layer further includes a pad facing an exterior of the photoelectric conversion device.

13. the second wiring layer further includes a fourth conductive portion for transmitting the anode potential in the pixel region; The photoelectric conversion device according to claim 1 , wherein the second conductive portion and the fourth conductive portion are spaced apart from each other.

14. A photoelectric conversion device having a semiconductor layer having an avalanche photodiode and a wiring structure electrically connected to the semiconductor layer, The photoelectric conversion device has, in a plan view with respect to the boundary between the semiconductor layer and the wiring structure, a pixel region having the avalanche photodiode; a peripheral region located between the pixel region and an outer edge of the photoelectric conversion device, the wiring structure includes a first wiring layer, a second wiring layer, and a third wiring layer; the third wiring layer is located between the first wiring layer and the second wiring layer, the first wiring layer includes, in the peripheral region, a first conductive portion for transmitting an anode potential of the avalanche photodiode; the second wiring layer includes a second conductive portion for transmitting a second potential different from the anode potential in the peripheral region; In the plan view, the first conductive portion and the second conductive portion overlap each other, the third wiring layer includes a third conductive portion that overlaps the first conductive portion and the second conductive portion in the plan view; No potential is supplied to the third conductive portion, the semiconductor layer has a charge drain portion in the peripheral region that collects charges in the semiconductor layer, The second conductive portion is connected to the charge discharging portion.

15. The photoelectric conversion device according to any one of claims 1 to 14, a signal processing unit that processes a signal output from the photoelectric conversion device.

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