Photoelectric conversion device, photoelectric conversion system, mobile object, and device

Abstract

To provide a technique that can improve the effect of restraining crosstalk while restraining noise caused by the electric field between a separator and an avalanche photodiode (APD).SOLUTION: A photoelectric conversion device includes a substrate having a first surface and a second surface, a plurality of photoelectric conversion elements each including an avalanche photodiode (APD), and an isolator that isolates the plurality of photoelectric conversion elements. Each of the plurality of photoelectric conversion elements includes a first semiconductor region and a second semiconductor region to which a first potential is applied, and the isolator includes a conductor to which a second potential is applied, and an insulating material. In a direction parallel to the first surface, the thickness of the insulating material at the same depth as the first semiconductor region is larger than the thickness of the insulating material at a depth located between the second semiconductor region and the second surface.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a photoelectric conversion device, a photoelectric conversion system, a mobile object, and an instrument. [Background technology]

[0002] There is known a photoelectric conversion device capable of detecting weak light at the single photon level by utilizing avalanche multiplication. Patent Document 1 discloses a photoelectric conversion device in which a sensor chip on which a plurality of pixels are arranged and a circuit chip on which a circuit for performing signal processing is formed are both electrically connected in a stacked structure. It is disclosed that avalanche photodiodes (APDs), in which electric charges undergo avalanche multiplication, are used for the pixels in the sensor chip of this photoelectric conversion device.

[0003] It is known that optical crosstalk (light leakage) between pixels can be suppressed by providing a separation section between pixels. It is also known that optical crosstalk can be further suppressed by including a metal in the separation section. Patent Document 2 discloses a configuration in which the separation section includes a metal covered with an insulator.

[0004] Patent Document 3 also reports on the phenomenon (avalanche emission) in which a large amount of electrons generated when an APD is driven recombine with holes to emit light. This document describes that, since emitted light leaks into adjacent pixels, causing problems such as false signals, the leakage of light into adjacent pixels can be suppressed by providing a trench structure containing insulating material, air, and metal in the separation section. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2017 / 0186798 [Patent Document 2] JP 2022-186423 A [Patent Document 3] Patent Publication No. 2021-34559 Summary of the Invention [Problem to be solved by the invention]

[0006] In a configuration in which the separation section includes a metal, a potential equivalent to the anode potential is applied to the metal to prevent dielectric breakdown. However, when this potential is applied to the metal, which is a conductor, a potential difference occurs between the separation section and the APD to which the cathode potential is applied, and the electric field strength between the separation section and the APD increases. When the electric field strength between the separation section and the APD increases, noise caused by the electric field becomes more likely to occur.

[0007] The present invention aims to provide a technology that can improve the crosstalk suppression effect while suppressing noise caused by the electric field between the separation section and the APD in a configuration in which the separation section includes a conductor. [Means for solving the problem]

[0008] A first aspect of the present invention includes a substrate having a first surface and a second surface facing the first surface and serving as a light incident surface, a plurality of photoelectric conversion elements provided on the substrate, each of the photoelectric conversion elements including an avalanche photodiode, and an isolation section is provided to isolate the plurality of photoelectric conversion elements, each of the plurality of photoelectric conversion elements including a first semiconductor region of a first conductivity type to which a first potential is applied and which constitutes the avalanche photodiode, and a second semiconductor region of a second conductivity type to which the avalanche photodiode is applied, the isolation section including a conductor to which a second potential different from the first potential is applied, and an insulator provided between the photoelectric conversion element and the conductor, This photoelectric conversion device is characterized in that, in a direction parallel to one surface, the thickness of the insulator at a first depth, which is the same depth as the first semiconductor region, is greater than the thickness of the insulator at a third depth, which is located between a second depth, which is the same depth as the second semiconductor region, and the second surface.

[0009] A second aspect of the present invention includes a substrate having a first surface and a second surface that faces the first surface and is a light incident surface; a first photoelectric conversion element and a second photoelectric conversion element that are provided on the substrate and each of which includes an avalanche photodiode; a separation portion that is located between the first photoelectric conversion element and the second photoelectric conversion element and separates at least the first surface side; and a separation portion that is located on the first surface side of the semiconductor substrate. a first wiring layer disposed on the insulating layer, the insulating layer including a first insulating material and a second insulating material; a first insulator and a second insulator are disposed between the conductor and the first photoelectric conversion element, the second insulator has a higher refractive index than the first insulator, and the second insulator extends to a first wiring layer.

[0010] A third aspect of the present invention is a photoelectric conversion system comprising the above-mentioned photoelectric conversion device and a signal processing unit that generates an image using a signal output by the photoelectric conversion device.

[0011] A fourth aspect of the present invention is a moving body comprising the above-mentioned photoelectric conversion device, characterized in that the moving body has a control unit that controls the movement of the moving body using a signal output by the photoelectric conversion device.

[0012] A fifth aspect of the present invention is an apparatus comprising the above-mentioned photoelectric conversion device, and at least one of an optical device corresponding to the photoelectric conversion device, a control device controlling the photoelectric conversion device, a processing device processing a signal output from the photoelectric conversion device, a display device displaying information obtained by the photoelectric conversion device, a memory device storing information obtained by the photoelectric conversion device, and a mechanical device operating based on information obtained by the photoelectric conversion device. Effect of the Invention

[0013] According to the present invention, in a configuration in which a conductor is included in a separation section, it is possible to improve the effect of suppressing crosstalk while suppressing noise caused by an electric field between the separation section and an APD. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of a photoelectric conversion device according to an embodiment. [Diagram 2] 2 is a schematic diagram of a pixel substrate of a photoelectric conversion device according to an embodiment. FIG. [Diagram 3] 2 is a schematic diagram of a circuit board of a photoelectric conversion device according to an embodiment. FIG. [Figure 4] 2 is a configuration example of a pixel circuit of a photoelectric conversion device according to an embodiment. [Diagram 5] 3 is a schematic diagram showing driving of a pixel circuit of a photoelectric conversion device according to an embodiment. FIG. [Figure 6] FIG. 1 is a plan view of a photoelectric conversion device according to a first embodiment. [Figure 7] 1 is a cross-sectional view of a photoelectric conversion device according to a first embodiment. [Figure 8] FIG. 11 is a cross-sectional view of a photoelectric conversion device as a comparative example. [Figure 9] FIG. 11 is a plan view of a photoelectric conversion device according to a second embodiment. [Figure 10] FIG. 11 is a cross-sectional view of a photoelectric conversion device according to a second embodiment. [Figure 11] FIG. 11 is a plan view of a photoelectric conversion device according to a third embodiment. [Figure 12] FIG. 11 is a cross-sectional view of a photoelectric conversion device according to a third embodiment. [Figure 13] FIG. 13 is a plan view of a photoelectric conversion device according to a fourth embodiment. [Figure 14] FIG. 11 is a cross-sectional view of a photoelectric conversion device according to a fourth embodiment. [Figure 15] FIG. 13 is a plan view of a photoelectric conversion device according to a fifth embodiment. [Figure 16] FIG. 11 is a cross-sectional view of a photoelectric conversion device according to a fifth embodiment. [Figure 17] FIG. 13 is a plan view of a photoelectric conversion device according to a comparative example of the fifth embodiment. [Figure 18] FIG. 13 is a cross-sectional view of a photoelectric conversion device according to a comparative example of the fifth embodiment. [Figure 19] 13A to 13C are cross-sectional views showing variations in the structure of the separation portion of the fifth embodiment. [Figure 20] 13A to 13C are cross-sectional views showing variations in the structure of the separation portion of the fifth embodiment. [Figure 21] 13A to 13C are cross-sectional views showing variations in the structure of the separation portion of the fifth embodiment. [Figure 22] 13A to 13C are cross-sectional views showing variations in the structure of the separation portion of the fifth embodiment. [Figure 23] FIG. 13 is a plan view of a photoelectric conversion device according to a sixth embodiment. [Figure 24] FIG. 13 is a cross-sectional view of a photoelectric conversion device according to a sixth embodiment. [Diagram 25] FIG. 13 is a plan view of a photoelectric conversion device according to a seventh embodiment. [Figure 26] FIG. 13 is a cross-sectional view of a photoelectric conversion device according to a seventh embodiment. [Figure 27] FIG. 13 is a diagram illustrating a photoelectric conversion system according to an eighth embodiment. [Figure 28] FIG. 13 is a diagram illustrating a photoelectric conversion system and a moving object according to a ninth embodiment. [Figure 29] FIG. 23 is a diagram illustrating a range image sensor according to a tenth embodiment. [Diagram 30] FIG. 19 is a diagram illustrating an endoscopic surgery system according to an eleventh embodiment. [Diagram 31] FIG. 23 is a diagram illustrating smart glasses according to a twelfth embodiment. [Diagram 32] FIG. 23 is a diagram illustrating an electronic device according to a thirteenth embodiment. [Diagram 33] FIG. 23 is a diagram illustrating an X-ray CT apparatus according to a fourteenth embodiment. [Diagram 34] FIG. 23 is a diagram illustrating an apparatus according to a fifteenth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The following embodiments are intended to embody the technical ideas of the present invention, and are not intended to limit the present invention. The sizes and positional relationships of the components shown in the drawings may be exaggerated to clarify the description. In the following description, the same components may be designated by the same reference numerals, and the description may be omitted.

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, "upper", "lower", "right", "left" and other terms including these terms) will be used as necessary. The use of these terms is for the purpose of facilitating understanding of the embodiment with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms.

[0017] In this specification, the plan view refers to a view from a direction perpendicular to the light incident surface of the semiconductor layer. Also, the cross-sectional view refers to a view from a direction perpendicular to the light incident surface of the semiconductor layer. Note that, when the light incident surface of the semiconductor layer is a rough surface when viewed microscopically, the plan view is defined based on the light incident surface of the semiconductor layer when viewed macroscopically.

[0018] The semiconductor layer has a first surface and a second surface, which is the surface opposite to the first surface and on which light is incident. In this specification, the depth direction is the direction from the first surface to the second surface of the semiconductor layer on which the avalanche photodiode (APD) is arranged. Hereinafter, the "first surface" may be referred to as the "front surface" and the "second surface" may be referred to as the "rear surface." The "depth" of a point or a region in the semiconductor layer means the distance from the first surface (front surface) of the point or region. When there is a point (or region) Z1 whose distance (depth) from the first surface is d1 and a point (or region) Z2 whose distance (depth) from the first surface is d2, and d1>d2, it may be expressed as "Z1 is deeper than Z2" or "Z2 is shallower than Z1." Also, when there is a point (or region) Z3 whose distance (depth) from the first surface is d3, and d1>d3>d2 holds, it can be expressed as "Z3 is at a depth between Z1 and Z2" or "Z3 is between Z1 and Z2 in the depth direction."

[0019] In the following explanation, the anode of the avalanche photodiode (APD) is set to a fixed potential, and the signal is taken from the cathode side. Therefore, the first conductivity type semiconductor region in which the charge of the same polarity as the signal charge is the majority carrier is an N-type semiconductor region, and the second conductivity type semiconductor region in which the charge of the opposite polarity to the signal charge is the majority carrier is a P-type semiconductor region. The present invention is also valid when the cathode of the APD is set to a fixed potential and the signal is taken out from the anode side. In this case, the first conductivity type semiconductor region in which charges of the same polarity as the signal charge are the majority carriers is a P-type semiconductor region, and the second conductivity type semiconductor region in which charges of a different polarity than the signal charge are the majority carriers is an N-type semiconductor region. In the following, a case in which one node of the APD is set to a fixed potential will be described, but the potentials of both nodes may fluctuate.

[0020] In this specification, when the term "impurity concentration" is used simply, it means the net impurity concentration minus the amount compensated by the impurity 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.

[0021] In addition, in the following embodiments, the connection between elements of a circuit may be described. In this case, even if another element is interposed between the elements of interest, the elements of interest are treated as being electrically connected to each other unless otherwise specified. For example, assume that an element A is connected to one node of a capacitive element C having multiple nodes, and an element B is connected to the other node. Even in such a case, the elements A and B are treated as being electrically connected to each other unless otherwise specified. In addition, when elements are connected to each other without other elements being interposed, they may be described as being directly connected. In the above example, when no other elements are provided between the element A and the capacitive element C, it can be said that the element A and the capacitive element C are directly connected.

[0022] Metallic members such as wiring and pads described in this specification may be composed of a single metal element or may be a mixture (alloy). For example, wiring described as copper wiring may be composed of a single copper element or may be composed mainly of copper and further contain other components. Also, for example, pads connected to external terminals may be composed of a single aluminum element or may be composed mainly of aluminum and further contain other components. The copper wiring and aluminum pads shown here are examples and can be changed to various metals.

[0023] Moreover, the wiring and pads shown here are one example of metal members used in a photoelectric conversion device, and the present invention can also be applied to other metal members.

[0024] In the following embodiments, an image pickup device will be mainly described as an example of a photoelectric conversion device. However, each embodiment is not limited to an image pickup device, and can be applied to other examples of photoelectric conversion devices. For example, a distance measuring device (a device for measuring distance using focus detection or TOF (Time Of Flight)) or a photometric device (a device for measuring the amount of incident light) may be used.

[0025] A configuration common to each embodiment of a photoelectric conversion device and a driving method thereof according to the present invention will be described with reference to FIGS. 1 to 5. FIG.

[0026] FIG. 1 is a diagram showing a configuration of a photoelectric conversion device 100 according to an embodiment of the present invention. In the following, a case where the photoelectric conversion device 100 is a stacked type photoelectric conversion device will be described as an example. That is, a photoelectric conversion device configured by stacking and electrically connecting two substrates, a sensor substrate 11 and a circuit substrate 21, will be described as an example. However, the photoelectric conversion device is not limited to this. For example, the photoelectric conversion device may be a photoelectric conversion device in which the configuration included in the sensor substrate 11 and the configuration included in the circuit substrate 21 are arranged on a common semiconductor layer, as described below. In the following, a photoelectric conversion device in which the configuration included in the sensor substrate 11 and the configuration included in the circuit substrate 21 are arranged on a common semiconductor layer will also be referred to as a non-stacked photoelectric conversion device.

[0027] The sensor substrate 11 has a first semiconductor layer having photoelectric conversion elements 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 configured by laminating the second semiconductor layer, the second wiring structure, the first wiring structure, and the first semiconductor layer in this order.

[0028] 1 illustrates a back-illuminated photoelectric conversion device in which light is incident from the second surface (rear surface) and a circuit board 21 is disposed on the first surface (front surface) that is the surface opposite the second surface. In the case of a non-stacked photoelectric conversion device, the surface on which the transistors of the signal processing circuit are disposed is referred to as the first surface. In the case of a front-illuminated photoelectric conversion device, the front surface is the second surface (light incident surface) and the back surface is the first surface.

[0029] In the following, the sensor substrate 11 and the circuit substrate 21 will be described as diced chips, but are not limited to chips. For example, each substrate may be a wafer. Also, each substrate may be stacked in a wafer state and then diced, or each chip may be stacked and bonded after being chipped.

[0030] A pixel region 12 is disposed on the sensor substrate 11, and a circuit region 22 that processes signals detected in the pixel region 12 is disposed on the circuit substrate 21.

[0031] 2 is a layout diagram of the sensor substrate 11. Pixels 101, each having a photoelectric conversion element 102 including an avalanche photodiode (APD), are arranged two-dimensionally to form a pixel region 12.

[0032] The pixel 101 is typically a pixel for forming an image, but when used for TOF (Time of Flight), it does not necessarily have to form an image. That is, the pixel 101 may be a pixel for measuring the time when light arrives and the amount of light.

[0033] 3 is a configuration diagram of the circuit board 21. It has a signal processing unit 103 that processes electric charges photoelectrically converted by the photoelectric conversion element 102 in FIG. 2, a readout circuit 112, a control pulse generating unit 115, a horizontal scanning circuit unit 111, signal lines 113, a vertical scanning circuit unit 110, drive lines 116, and an output circuit 114.

[0034] The photoelectric conversion element 102 in FIG. 2 and the signal processing unit 103 in FIG. 3 are electrically connected via connection wiring provided for each pixel.

[0035] The vertical scanning circuit section 110 receives a control pulse supplied from a control pulse generating section 115, and supplies the control pulse to each pixel via a driving line 116. The vertical scanning circuit section 110 uses logic circuits such as a shift register and an address decoder.

[0036] The control pulse generating unit 115 has a signal generating unit 215 that generates a control signal P_CLK for a switch, which will be described later. The signal generating unit 215 generates a pulse signal for controlling the switch, as will be described later. For example, as shown in FIG. 4(A), the signal generating unit 215 may generate a common control signal P_CLK for a plurality of pixels in the pixel region 12, or as shown in FIG. 4(B), the control signal P_CLK may be generated for each pixel. When the common pulse signal P_CLK is generated, at least one of the period, the number of pulses, and the pulse width of the signal P_EXP pulse signal that controls the exposure period is generated in common in correspondence with the exposure period. When the control signal P_CLK is controlled for each pixel, a signal can be generated using both the input signal P_CLK_IN output from the control pulse generating unit 115 and the signal P_EXP that controls the exposure period. The control pulse generating unit 115 preferably has, for example, a frequency dividing circuit. This allows simple control and increases the number of elements. This can reduce the amount of damage that occurs.

[0037] The signal output from the photoelectric conversion element 102 of each pixel is processed by a signal processing unit 103. The signal processing unit 103 is provided with a counter, a memory, etc., and digital values ​​are held in the memory.

[0038] The horizontal scanning circuit unit 111 inputs a control pulse for sequentially selecting each column to the signal processing unit 103 in order to read out the signal from the memory of each pixel in which the digital signal is held.

[0039] A signal is output to the signal line 113 from the signal processing unit 103 of the pixel selected by the vertical scanning circuit unit 110 for the selected column.

[0040] The signal output to the signal line 113 is output via an output circuit 114 to a recording unit or a signal processing unit outside the photoelectric conversion device 100 .

[0041] 2, the pixels 101 may be arranged one-dimensionally in the pixel region 12. The function of the signal processing unit 103 does not necessarily need to be provided for each pixel 101, and for example, one signal processing unit 103 may be shared by a plurality of pixels 101 to perform signal processing sequentially.

[0042] Figures 4(A) and 4(B) are examples of block diagrams including the equivalent circuits of Figures 2 and 3. Figure 4(A) is an example in which the signal generating unit 215 is provided in common to a plurality of pixels, and Figure 4(B) is an example in which the control signal P_CLK can be controlled for each pixel. Figure 4(A) will be explained.

[0043] In FIG. 4A, a photoelectric conversion element 102 having an APD 201 is provided on a sensor substrate 11, and other members are provided on a circuit substrate 21.

[0044] The APD 201 generates charge pairs according to the incident light by photoelectric conversion. A voltage VL (first voltage) is supplied to the anode of the APD 201. A voltage VH (second voltage) higher than the voltage VL supplied to the anode is supplied to the cathode of the APD 201. A reverse bias voltage that causes the APD 201 to perform avalanche multiplication is supplied to the anode and cathode. With such a voltage supplied, the charges generated by the incident light undergo avalanche multiplication, generating an avalanche current.

[0045] When a reverse bias voltage is supplied, there are two modes: Geiger mode, in which the potential difference between the anode and cathode is greater than the breakdown voltage, and linear mode, in which the potential difference between the anode and cathode is close to or less than the breakdown voltage. An APD operated in Geiger mode is called a SPAD. For example, the voltage VL (first voltage) is -30V, and the voltage VH (second voltage) is 1V. The APD201 may be operated in either linear mode or Geiger mode. In the case of a SPAD, the potential difference is greater than in a linear mode APD, and the effect of withstanding voltage becomes more pronounced.

[0046] The switch 202 is connected to a power supply line to which a drive voltage VH is supplied and to the APD 201. The switch 202 is connected to one of the anode and cathode nodes of the APD 201. The switch 202 switches the potential difference between the anode and cathode of the APD 201 between a first potential difference that causes avalanche multiplication and a second potential difference that does not cause avalanche multiplication. Hereinafter, switching from the second potential difference to the first potential difference is also referred to as turning on the switch 202, and switching from the first potential difference to the second potential difference is also referred to as turning off the switch 202. The switch 202 functions as a quenching element. The switch 202 switches between a first potential difference that causes avalanche multiplication and a second potential difference that does not cause avalanche multiplication. The switch 202 functions as a load circuit (quench circuit) during signal multiplication by the APD 201, suppressing the voltage supplied to the APD 201 and suppressing avalanche multiplication (quench operation). The switch 202 also functions to return the voltage supplied to the APD 201 to the drive voltage VH by flowing a current equivalent to the voltage drop caused by the quench operation (recharge operation). In other words, the switch 202 functions as a control circuit that controls the occurrence of avalanche multiplication in the APD 201.

[0047] The switch 202 can be configured, for example, by a MOS transistor. A control signal P_CLK for the switch 202, which is supplied from the signal generating unit 215, is applied to a gate electrode of the MOS transistor that configures the switch 202. In this embodiment, the on / off of the switch 202 is controlled by controlling the voltage applied to the gate electrode of the switch 202.

[0048] The signal processing section 103 has a waveform shaping section 210, a counter circuit 211, and a selection circuit 212. In this specification, it is sufficient that the signal processing section 103 has at least one of the waveform shaping section 210, the counter circuit 211, and the selection circuit 212.

[0049] The waveform shaping unit 210 shapes the potential change of the cathode of the APD 201 obtained when a photon is detected, and outputs a pulse signal. The node on the input side of the waveform shaping unit 210 is nodeA, and the node on the output side is nodeB. The waveform shaping unit 210 changes the output potential from the node nodeB depending on whether the input potential to the node nodeA is equal to or higher than a predetermined value or lower. For example, in FIG. 5, when the input potential to the node nodeA becomes a high potential equal to or higher than the judgment threshold, the output potential from the node nodeB becomes a low level. When the input potential to the node nodeA becomes a potential lower than the judgment threshold, the output potential from the node nodeB becomes a high level. For example, an inverter circuit is used as the waveform shaping unit 210. In FIG. 4(A), an example in which one inverter is used as the waveform shaping unit 210 is shown, but a circuit in which multiple inverters are connected in series may be used, or other circuits having a waveform shaping effect may be used.

[0050] It is possible to perform a quench operation and a recharge operation using the switch 202 according to the avalanche multiplication in the APD 201, but depending on the timing of photon detection, the charge generated in the APD 201 may not be determined as an output signal. For example, assume that avalanche multiplication occurs in the APD 201, the node nodeA becomes low level, and a recharge operation is performed. In general, the decision threshold of the waveform shaping unit 210 is set to a potential higher than the potential difference at which avalanche multiplication occurs in the APD 201. When a photon is incident on the APD 201 when the potential of the node nodeA is lower than the decision threshold due to the recharge operation and the potential is such that avalanche multiplication is possible in the APD 201, avalanche multiplication occurs in the APD 201 and the voltage of the nodeA drops. In other words, since the potential of the nodeA drops at a voltage lower than the decision threshold, no potential change occurs across the decision threshold, and the output potential from the node nodeB does not change. Therefore, even though avalanche multiplication occurs, the photon detection is not determined as a signal. Particularly under high illuminance, photons enter the APD 201 continuously in a short period of time, making it difficult to determine the incident light as a signal. As a result, even under high illuminance, the actual number of incident photons and the output signal tend to diverge.

[0051] In contrast, by applying a control signal P_CLK to the switch 202 to switch the switch 202 between its on and off states, it is possible to determine a signal even when photons enter the APD 201 successively within a short period of time. FIG. 5 illustrates an example in which the control signal P_CLK is a pulse signal with a repetitive cycle. In other words, FIG. 5 illustrates a form in which the switch 202 is switched on and off at a predetermined clock frequency. However, the effect of suppressing an increase in power consumption of the photoelectric conversion device 100 is not as strong as when the pulse signal is a signal with a repetitive cycle. It is possible to get without it.

[0052] The counter circuit 211 counts the pulse signal output from the waveform shaping unit 210 and holds the count value. When a control pulse pRES is supplied via a drive line 213, the signal held in the counter circuit 211 is reset.

[0053] A control pulse pSEL is supplied to the selection circuit 212 from the vertical scanning circuit unit 110 in Fig. 3 via the drive line 214 in Fig. 4(A), and switches between electrical connection and non-connection between the counter circuit 211 and the signal line 113. The selection circuit 212 includes, for example, a buffer circuit for outputting a signal.

[0054] The electrical connection may be switched by disposing a switch such as a transistor between the switch 202 and the APD 201 or between the photoelectric conversion element 102 and the signal processing unit 103. 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.

[0055] In this embodiment, a configuration using the counter circuit 211 has been shown. However, instead of the counter circuit 211, the photoelectric conversion device 100 may acquire the pulse detection timing using a time-to-digital converter (hereinafter, referred to as TDC) or a memory. 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. In order to measure the timing of the pulse signal, a control pulse pREF (reference signal) is supplied to the TDC from the vertical scanning circuit unit 110 in FIG. 3 via a drive line. The TDC acquires, as a digital signal, a value obtained by converting the input timing of the signal output from each pixel into a relative time based on the control pulse pREF.

[0056] FIG. 5 is a diagram showing a schematic diagram of the relationship between the control signal P_CLK of the switch, the potential of the node nodeA, the potential of the node nodeB, and the output signal. In this embodiment, when the control signal P_CLK is at a high level, the drive voltage VH is not easily supplied to the APD 201, and when the control signal P_CLK is at a low level, the drive voltage VH is supplied to the APD 201. The high level of the control signal P_CLK is, for example, 1V, and the low level of the control signal P_CLK is, for example, 0V. When the control signal P_CLK is at a high level, the switch is turned off, and when the control signal P_CLK is at a low level, the switch is turned on. The resistance value of the switch when the control signal P_CLK is at a high level is higher than the resistance value of the switch when the control signal P_CLK is at a low level. When the control signal P_CLK is at a high level, even if avalanche multiplication occurs in the APD 201, a recharge operation is not easily performed, so the potential supplied to the APD 201 is a potential equal to or lower than the breakdown voltage of the APD 201. Therefore, the avalanche multiplication operation in the APD 201 is stopped.

[0057] As shown in Fig. 4(A), it is preferable to configure the switch 202 with one transistor, and to perform the quenching operation and the recharge operation with one transistor. This makes it possible to reduce the number of circuits compared to the case where the quenching operation and the recharge operation are performed with different circuit elements. In particular, when each pixel has a counter circuit and the SPAD signal is read out for each pixel, it is preferable to reduce the circuit area used for the switch in order to place the counter circuit, and the effect of configuring the switch 202 with one transistor becomes significant.

[0058] At time t1, the control signal P_CLK changes from high to low, turning on the switch and starting the recharge operation of the APD 201. This causes the potential of the cathode of the APD 201 to transition to a high level. The potential difference of the potential applied to the cathode is in a state where avalanche multiplication is possible. The potential of the cathode is the same as that of node nodeA. Therefore, when the potential of the cathode transitions from low level to high level, the potential of node nodeA becomes equal to or higher than the decision threshold at time t2. At this time, the pulse signal output from node nodeB is inverted and goes from high level to low level. After that, the potential difference of drive voltage VH-drive voltage VL is applied to APD 201. The control signal P_CLK goes high level and the switch is turned off.

[0059] Next, at time t3, when a photon is incident on the APD 201, avalanche multiplication occurs in the APD 201, and the voltage of the cathode drops. That is, the voltage of the node nodeA drops. When the amount of voltage drop becomes larger and the voltage difference applied to the APD 201 becomes smaller, the avalanche multiplication of the APD 201 stops as at time t2, and the voltage level of the node nodeA does not drop by more than a certain value. When the voltage of the node nodeA becomes lower than the decision threshold while the voltage of the node nodeA is dropping, the voltage of the node nodeB goes from low level to high level. That is, the part of the output waveform at the node nodeA that exceeds the decision threshold is waveform-shaped by the waveform shaping unit 210 and output as a signal at the nodeB. Then, it is counted by the counter circuit, and the count value of the counter signal output from the counter circuit increases by 1 LSB.

[0060] Between time t3 and time t4, photons are incident on the APD 201. However, since the switch is in the off state and the voltage applied to the APD 201 does not have a potential difference that allows avalanche multiplication, the voltage level of the node A does not exceed the decision threshold.

[0061] At time t4, the control signal P_CLK changes from high to low, and the switch is turned on. As a result, a current flows to node A to compensate for the voltage drop from the drive voltage VH, and the voltage of node A transitions to its original voltage level. At this time, the voltage of node A becomes equal to or higher than the decision threshold at time t5, so the pulse signal of node B is inverted and goes from high to low.

[0062] At time t6, node A is stabilized to the original voltage level, and the control signal P_CLK goes from low to high. Therefore, the switch is turned off. After this, the potentials of the nodes and signal lines change in response to the control signal P_CLK and the incidence of photons, as described from time t1 to time t6.

[0063] The photoelectric conversion devices of the respective embodiments will be described below.

[0064] (First embodiment) 6(A) to 6(C), 7(A), and 7(B) show the structure of the sensor substrate 11 of the photoelectric conversion device according to the first embodiment. FIG. 6(A) is a plan view at a depth D1 (first depth) which is the same depth as the first semiconductor region 301 in FIG. 7(A). FIG. 6(B) is a plan view at a depth D2 (second depth) which is the same depth as the fourth semiconductor region 304 in FIG. 7(A). FIG. 6(C) is a plan view at a depth D3 (third depth) located between the depth D2 and the second surface in FIG. 7(A). FIG. 7(A) is a cross-sectional view taken along the line AA (diagonal direction) in FIG. 6(A). FIG. 7(B) is a cross-sectional view taken along the line BB (opposite side direction) in FIG. 6(A).

[0065] 6A, for convenience of illustration, only one APD 201 is illustrated, but in an actual product, for example, hundreds of thousands to millions of APDs 201 are formed in a two-dimensional array. One APD 201 corresponds to one pixel.

[0066] 7A, the sensor substrate 11 has a structure in which a semiconductor layer 300 and a wiring structure 320 are laminated. The surface of the semiconductor layer 300 facing the wiring structure 320 is referred to as a first surface. The surface on the opposite side of the first surface is called the second surface. The semiconductor layer 300 is made of silicon, for example. On the second surface of the semiconductor layer 300, a fixed charge film 310, an insulating film 311, a planarization film 312, and the like are laminated in this order, and a microlens 313 corresponding to each pixel is further provided above them. That is, the photoelectric conversion device according to the first embodiment has a so-called back-illuminated structure in which light is incident on the semiconductor layer 300 from the second surface side. The second surface is sometimes called a light incident surface. In addition, the following structure can be applied to the light incident surface. For example, an uneven structure such as at least one or more concave or convex portions is arranged on the second surface, which is the light incident surface. The uneven structure is formed by silicon constituting the semiconductor layer 300 and other members. For example, an insulator such as a silicon oxide film, a silicon oxynitride film, or a silicon nitride film is arranged in a concave portion provided in the semiconductor layer 300. An interface having a refractive index difference that is not parallel to the second surface is formed. With such a configuration, the incident light is diffracted, and the sensitivity to light in the infrared region can be improved.

[0067] The fixed charge film 310 is made of a dielectric having a negative fixed charge and is disposed over the entire second surface of the semiconductor layer 300. The material of the fixed charge film 310 is selected from, for example, hafnium oxide, aluminum oxide, zirconium oxide, titanium oxide, tantalum oxide, and ruthenium oxide, and among them, aluminum oxide or hafnium oxide is preferable. The fixed charge film 310 may be configured to be composed of multiple layers. The insulating film 311 is disposed over the entire second surface on the fixed charge film 310. For example, a silicon oxide film, a silicon oxynitride film, or a silicon nitride film can be suitably used as the insulating film 311. The insulating film 311 may be configured to be composed of multiple layers. Although not shown, in addition to the planarization film 312, a filter layer such as a color filter or an infrared light cut filter may be provided on the second surface side of the semiconductor layer 300.

[0068] Wiring structure 320 is a structure in which wiring 321, anode wiring contact plug 324, cathode wiring contact plug 326, etc. are arranged in insulating layer 329. The lower surface of wiring structure 320 (the surface opposite to semiconductor layer 300) is a bonding surface with circuit board 21, and a plurality of bonding portions 328 (metal bonding) are provided on the bonding surface.

[0069] The semiconductor layer 300 has a first semiconductor region 301, a second semiconductor region 302, a third semiconductor region 303, a fourth semiconductor region 304, a fifth semiconductor region 305, a sixth semiconductor region 306, a seventh semiconductor region 307, and an eighth semiconductor region 308. Each semiconductor region is a region to which impurities are added by ion implantation, or a region to which impurities are added during the preparation and epitaxial growth of a semiconductor substrate. Here, the first semiconductor region 301, the fifth semiconductor region 305, the sixth semiconductor region 306, and the seventh semiconductor region 307 are semiconductor regions of a first conductivity type (N type in the first embodiment). The second semiconductor region 302, the third semiconductor region 303, the fourth semiconductor region 304, and the eighth semiconductor region 308 are semiconductor regions of a second conductivity type (P type in the first embodiment).

[0070] The first semiconductor region 301 is a semiconductor region of a first conductivity type (N type in the first embodiment), and is provided on a first surface of the semiconductor layer 300. As shown in Fig. 6(A), the first semiconductor region 301 is formed in a circular shape in the center of a pixel (section) in a plan view.

[0071] The fourth semiconductor region 304 is a semiconductor region of the second conductivity type (P type in the first embodiment) and is disposed on the light incident side (closer to the second surface) than the first semiconductor region 301. The fourth semiconductor region 304 is formed in a layer shape at a predetermined depth so as to divide the first conductivity type epitaxial layer in one pixel (section) into upper and lower parts. The periphery of the fourth semiconductor region 304 is in contact with a separation portion 331 that surrounds the pixel. The first conductivity type epitaxial layer located closer to the first surface than the fourth semiconductor region 304 is a fifth semiconductor region 305, and the first conductivity type epitaxial layer located closer to the second surface is a seventh semiconductor region 307.

[0072] The first semiconductor region 301 of the first conductivity type and the fourth semiconductor region 304 of the second conductivity type form an avalanche multiplication unit AM by a PN junction. Signal charges generated in the seventh semiconductor region 307 by photoelectric conversion are collected in the avalanche multiplication unit AM. In order to improve the sensitivity of the pixel (APD 201), it is preferable to increase the size of the seventh semiconductor region 307, which corresponds to the sensitive region.

[0073] The sixth semiconductor region 306 is a semiconductor region of the first conductivity type formed around the first semiconductor region 301. The sixth semiconductor region 306 is also formed in a circular shape in a plan view. Here, the impurity concentrations of the first semiconductor region 301, the sixth semiconductor region 306, and the fifth semiconductor region 305 are set to satisfy the relationship of first semiconductor region 301>sixth semiconductor region 306>fifth semiconductor region 305. That is, the impurity concentration of the first semiconductor region 301 is the highest, and the impurity concentration of the sixth semiconductor region 306 is set to be between the first semiconductor region 301 and the fifth semiconductor region 305. This makes it possible to ensure electrical connection between the cathode and the first semiconductor region 301 (i.e., the APD 201). In addition, the sixth semiconductor region 306 plays a role of a guard ring for alleviating an electric field.

[0074] The eighth semiconductor region 308 is a buried layer of the second conductivity type provided so as to constitute a part of the second surface of the semiconductor layer 300. The periphery of the eighth semiconductor region 308 is in contact with the separation portion 331 surrounding the pixel. The eighth semiconductor region 308 plays a role in suppressing noise from the second surface side. In addition, a voltage VL from the anode wiring can be supplied to the eighth semiconductor region 308 via the second semiconductor region 302. In this case, a potential gradient can be formed for collecting charges.

[0075] A third semiconductor region 303 is provided on the first surface of the semiconductor layer 300 as a connection portion for electrically connecting between the contact plug 324 of the anode wiring and the second semiconductor region 302 of the isolation portion 331. The second semiconductor region 302 and the third semiconductor region 303 are both of the second conductivity type (P type in the first embodiment). As shown in FIG. 7(A), the third semiconductor region 303 is disposed in a portion corresponding to the contact plug 324.

[0076] As shown in FIG. 7B, the semiconductor layer 300 is provided with a separation section 331, which is an isolation structure for reducing optical crosstalk (light leakage) between adjacent APDs 201, 201. An APD 201 is disposed in each of the sections divided by the separation section 331. In this manner, a plurality of photoelectric conversion elements 102, each including an APD 201, are isolated by the separation section 331. The section corresponding to one pixel has a substantially square shape in a plan view. In other words, the separation section 331 surrounds one pixel with a substantially rectangular shape in a plan view. A contact plug 326 of a cathode wiring formed in the wiring structure 320 is disposed substantially at the center of the pixel (section), and a contact plug 324 of an anode wiring is disposed at an end of the pixel.

[0077] The isolation portion 331 suppresses the movement of electrons between pixels by a potential barrier. The isolation portion 331 also constitutes a part of the second surface of the semiconductor layer 300. The isolation portion 331 has a metal trench 341, an insulating film (insulating isolation layer) 351, and a second semiconductor region 302 of a second conductivity type (P type in the first embodiment). The metal trench 341 can be preferably made of a conductor such as tungsten, titanium, tantalum, aluminum, gold, silver, copper, platinum, or a material containing a metal compound. The metal trench 341 may be a DTI (Deep Trench Isolation) penetrating the semiconductor layer. The insulating film 311 can be preferably made of an insulator such as a silicon oxide film, a silicon oxynitride film, or a silicon nitride film. The insulating film 351 is provided between the photoelectric conversion element 102 and the metal trench 341. In the first embodiment, the insulating film 351 is provided so as to surround the metal trench 341. The second semiconductor region 302 is provided to surround the insulating film 351 .

[0078] A predetermined potential is applied to the metal trench 341 so that the state of the pixel boundary portion does not become unstable. The predetermined potential is preferably a potential equivalent to the voltage VL (first potential) supplied to the second semiconductor region 302. This is because if the potential applied to the metal trench 341 differs from the potential applied to the second semiconductor region 302, dielectric breakdown may occur. Note that a voltage VH (second voltage) is supplied to the first semiconductor region 301, which is a semiconductor region of a first conductivity type (N type in the first embodiment). That is, a second potential different from the first potential applied to the semiconductor region of the first conductivity type is applied to the metal trench 341.

[0079] Fig. 8 shows the structure of sensor substrate 11 of a photoelectric conversion device as a comparative example. Fig. 8 is a cross-sectional view in the opposite side direction of sensor substrate 11. As shown in Fig. 8, sensor substrate 11 of the comparative example and sensor substrate 11 according to the first embodiment have the same basic configuration.

[0080] A voltage VL (e.g., −30 V) is supplied to the metal trench 341 of the isolation portion 330 to prevent dielectric breakdown. A voltage VH (e.g., 1 V) is supplied to the first semiconductor region 301. In the configuration of the isolation portion 330 of the comparative example, the thickness of the insulating film 350 at the depth D1 is the same as the thickness of the insulating film 350 at the depth D3, and is thin. Therefore, when a large potential difference occurs between the metal trench 341 and the first semiconductor region 301, the electric field strength therebetween becomes large in the configuration of the isolation portion 330 of the comparative example.

[0081] Here, the area closer to the second surface (light incident surface) than depth D2 is a sensitivity area where charges are generated in response to incident light. The area closer to the first surface (surface opposite to the second surface) than depth D2 is a multiplication area where the generated charges undergo avalanche multiplication. Note that depth D1 is the same depth as first semiconductor region 301, depth D2 is the same depth as fourth semiconductor region 304, and depth D3 is a depth located between depth D2 and the second surface. Depth D3 is also the same depth as seventh semiconductor region 307.

[0082] In the multiplication region, it is preferable that the electric field strength of the signal path (electric field strength between the first semiconductor region 301 and the fourth semiconductor region 304) is large and the electric field strength of other than the signal path is small. This is because a large electric field strength of other than the signal path causes noise. Therefore, at a depth D1 included in the multiplication region, it is preferable that the electric field strength of other than the signal path, that is, the electric field strength between the metal trench 341 and the first semiconductor region 301, is low.

[0083] Therefore, in the first embodiment, the thickness of the insulating film 351 at the depth D1 is made thicker than the insulating film 350 of the comparative example. Specifically, as shown in FIG. 7A, in the direction parallel to the first surface, the thickness T1 of the insulating film 351 at the depth D1 is greater than the thickness T3 of the insulating film 351 at the depth D3. The depth D1 is a depth included in the multiplication region, and the depth D3 is a depth located on the second surface side of the multiplication region and included in the sensitive region. This makes it possible to reduce the electric field strength (alleviate the electric field) between the metal trench 341 and the first semiconductor region 301 at the depth D1. Note that it is sufficient that the thickness T1 of the insulating film 351 on the side where the first semiconductor region 301 is located at least at the depth D1 is greater than the thickness T3 of the insulating film 351 at the depth D3. Also, unlike the thickness T1 of the insulating film 351 at the depth D1, by not making the thickness T3 of the insulating film 351 at the depth D3 thick, the size of the sensitive region is not reduced, and a decrease in sensitivity can be avoided.

[0084] 7A, in the first embodiment, a thickness T1 of the insulating film 351 at a depth D1 is greater than a thickness T2 of the insulating film 351 at a depth D2. Also, as shown in FIG 7B, the thickness T1 of the insulating film 351 at a depth D1 is greater than a total thickness T4 of the thickness of the third semiconductor region 303 and the thickness of the insulating film 351 at a depth D3.

[0085] The insulating film on the first surface side of the boundary between the fourth semiconductor region 304 and the sixth semiconductor region 306 It is more preferable that the thickness of 351 is larger than the thickness T3 of the insulating film 351 at the depth D3, because the electric field strength between the metal trench 341 and the first semiconductor region 301 can be reduced more effectively in the multiplication region.

[0086] 7A, the thickness of the insulating film 351 decreases from the depth D1 toward the depth D2, but is not limited to this. It is sufficient that the thickness T1 of the insulating film 351 at the depth D1 is greater than the thickness T3 of the insulating film 351 at the depth D3. In addition, in the plan view of FIG. 6A, the boundary between the insulating film 351 and the fifth semiconductor region 305 is shown as an octagon, but is not limited to this and may be, for example, a rectangle or a circle.

[0087] In this manner, in the first embodiment, the thickness T1 of the insulating film 351 at the depth D1 is set to be greater than the thickness T3 of the insulating film 351 at the depth D3. This makes it possible to improve the crosstalk suppression effect while suppressing noise caused by the electric field between the isolation portion 331 and the APD 201 in a configuration that uses the isolation portion 331 containing a metal.

[0088] Second embodiment 9(A) to 9(C), 10(A), and 10(B) show the structure of the sensor substrate 11 of the photoelectric conversion device according to the second embodiment. FIG. 9(A) is a plan view at a depth D1 which is the same depth as the first semiconductor region 301 in FIG. 10(A). FIG. 9(B) is a plan view at a depth D2 which is the same depth as the fourth semiconductor region 304 in FIG. 10(A). FIG. 9(C) is a plan view at a depth D3 located between the depth D2 and the second surface in FIG. 10(A). FIG. 10(A) is a cross-sectional view taken along the line AA (diagonal direction) in FIG. 9(A). FIG. 10(B) is a cross-sectional view taken along the line BB (opposite side direction) in FIG. 9(A). Hereinafter, a configuration different from the first embodiment will be described.

[0089] In the first embodiment, an anode electrode (contact plug 324) is provided on the first surface side separately from the metal trench 341. However, in the manufacturing process, a space must be secured between the metal trench 341 and the contact plug 324, which may not be suitable for miniaturizing pixels. Therefore, in the second embodiment, the metal trench 342 of the separation section 332 is made to double as the anode electrode. This eliminates the need to secure a space between the metal trench 341 and the contact plug 324, allowing the pixel to be further miniaturized. In addition, the anode electrode is formed using the same material and in the same manufacturing process as the metal trench 341, which further simplifies the manufacturing process of the sensor substrate 11.

[0090] 10(A), at least a portion of the metal trench 342 is in contact with the third semiconductor region 303, and an anode potential is supplied to the third semiconductor region 303 via the metal trench 342. Note that, as shown in FIG. 10(A), it is preferable to secure a certain area where the insulating film 351 contacts the third semiconductor region 303. This is because if the area where the metal trench 342 and the third semiconductor region 303 contact each other is large, noise may be generated.

[0091] Third embodiment 11(A) to 11(C), 12(A), and 12(B) show the structure of the sensor substrate 11 of the photoelectric conversion device according to the third embodiment. FIG. 11(A) is a plan view at a depth D1 which is the same depth as the first semiconductor region 301 in FIG. 12(A). FIG. 11(B) is a plan view at a depth D2 which is the same depth as the fourth semiconductor region 304 in FIG. 12(A). FIG. 11(C) is a plan view at a depth D3 located between the depth D2 and the second surface in FIG. 12(A). FIG. 12(A) is a cross-sectional view taken along the line AA (diagonal direction) in FIG. 11(A). FIG. 12(B) is a cross-sectional view taken along the line BB (opposite side direction) in FIG. 11(A). Hereinafter, a configuration different from the first embodiment will be described.

[0092] In the first embodiment, a metal trench 341 is provided that penetrates from the insulating layer 329 to the depth of the eighth semiconductor region 308. However, although the provision of the metal trench 341 can suppress optical crosstalk, the incident light is also absorbed in the metal trench 341 to a certain extent, which may reduce sensitivity. Therefore, in the third embodiment, as shown in FIGS. 12(A) and 12(B), a metal trench 343 that does not penetrate in the depth direction is provided. Specifically, the metal trench 343 is at a depth D1 but not at a depth D3. This makes it possible to avoid a decrease in sensitivity caused by the metal trench 343 absorbing the incident light while suppressing optical crosstalk.

[0093] The separation unit 333 has an insulating film 352 which is a portion farther from the second surface (light incident surface) and an insulating film 353 which is a portion closer to the second surface. The metal trench 343 is provided only in the insulating film 352. The insulating films 352 and 353 may be made of the same material or different materials. The insulating film does not have to be divided into the insulating film 352 and the insulating film 353.

[0094] (Fourth embodiment) 13(A) to 13(C), 14(A), and 14(B) show the structure of the sensor substrate 11 of the photoelectric conversion device according to the fourth embodiment. FIG. 13(A) is a plan view at a depth D1 which is the same depth as the first semiconductor region 301 in FIG. 14(A). FIG. 13(B) is a plan view at a depth D2 which is the same depth as the fourth semiconductor region 304 in FIG. 14(A). FIG. 13(C) is a plan view at a depth D3 located between the depth D2 and the second surface in FIG. 14(A). FIG. 14(A) is a cross-sectional view taken along the line AA (diagonal direction) in FIG. 13(A). FIG. 14(B) is a cross-sectional view taken along the line BB (opposite side direction) in FIG. 13(A). Hereinafter, a configuration different from the third embodiment will be described.

[0095] In the third embodiment, the anode electrode (contact plug 324) is provided on the first surface side. However, in the manufacturing process, a space must be secured between the metal trench 343 and the contact plug 324, which may not be suitable for miniaturization of pixels. Therefore, in the fourth embodiment, the contact plug 324 is provided on the second surface side, not on the first surface side. This eliminates the need to secure a space between the metal trench 343 and the contact plug 324, allowing the pixel to be further miniaturized. An anode potential is supplied to the third semiconductor region 303 via the wiring 321 and the contact plug 324 provided on the second surface side, and an anode potential is supplied to the metal trench 343 via the wiring 321 provided on the first surface side.

[0096] Fifth embodiment Figures 15, 16(A), and 16(B) show the structure of a sensor substrate 11 of a photoelectric conversion device according to the fifth embodiment. Figure 15 is a plan view at a depth D1, which is the same depth as the first semiconductor region 301 in Figure 16(A). Figure 16(B) is a cross-sectional view taken along line BB (opposite side direction) in Figure 15.

[0097] In the fifth embodiment, the isolation portion 333 is composed of a metal trench 343 , an insulating film 352 , and an optical film 354 .

[0098] As for the materials, for example, the insulating film 352 is a silicon oxide film with a refractive index of 1.46, the optical film 354 is a silicon nitride film with a refractive index of 2.02, and the metal trench 343 is made of tungsten with a reflectance of 35% and titanium nitride with a reflectance of 50%. However, this is only an example, and other materials mentioned above can also be used.

[0099] The material of the optical film 354 may be an insulating film having a higher refractive index than the insulating film 352. For example, in addition to the silicon nitride film described above, a silicon oxynitride film, aluminum oxide, etc. can be used. Furthermore, a film with low transmittance is even better, and in this case, titanium nitride, tantalum compounds, etc. can be used.

[0100] Insulating film 343 extends with metal trench 343 to wiring structure 320 and is further disposed parallel to the first surface.

[0101] 17, 18(A), and 18(B) show the structure of a comparative example for explaining the effect of the fifth embodiment. FIG. 17 is a plan view at a depth D1, which is the same depth as the first semiconductor region 301 in FIG. 18(A). FIG. 18(B) is a cross-sectional view taken along line BB (opposite side direction) in FIG. 17. The comparative example differs from the fifth embodiment in that the separation portion 333 does not include the optical film 354. Hereinafter, the additional effect of "suppressing leakage of avalanche emission light into adjacent pixels" obtained in the fifth embodiment will be explained using the comparative example.

[0102] 17, the location where avalanche light emission occurs is the multiplication region in the vicinity of the first semiconductor region 301. The light emission phenomenon occurs when some of the electrons that are generated in large quantities recombine with holes.

[0103] The comparative example differs from the fifth embodiment in that the separation portion 333 does not include the optical film 354. Therefore, in the comparative example, as shown by the arrow 360 in Fig. 18(A) , a part of the light of the avalanche emission is absorbed by the metal trench 343, but a part of the light is reflected and then leaks into an adjacent pixel via the path indicated by the dotted line, resulting in a false signal of the adjacent pixel.

[0104] In contrast, in the fifth embodiment, as shown by arrow 370 in FIG. 16(A), the optical film 354 prevents the avalanche emission light from being reflected by the metal trench 343, so that the amount of light leaking into adjacent pixels can be suppressed.

[0105] 19(A) to 19(D), 20(A) to 20(C), 21(A) to 21(D), and 22(A) to 22(C) show structural variations of the separation section 333.

[0106] 19(A), 19(B), and 19(C) show the positional relationship of the insulating film 352 and the optical film 354 with respect to the metal trench 343. The desired effect can be obtained whether the optical film 354 is located outside the insulating film 352 with respect to the metal trench 343 (FIG. 19(A)), whether it is located inside (FIG. 19(B)), or even whether it is sandwiched between both the inside and outside (FIG. 19(C)). In addition, as shown in FIG. 19(D), the effect of preventing reflection can be obtained by providing the optical film 354 even in a part of the depth of the semiconductor layer. Furthermore, as shown in FIG. 19(E), the effect of suppressing the decrease in sensitivity can be obtained as in the third embodiment by connecting the remaining semiconductor layer close to the second surface with the insulating film 353.

[0107] 20(A), 20(B), and 20(C) show structural variations in which optical film 354 extends to wiring structure 320 and then exists as a film parallel to the first surface.

[0108] Since the light of avalanche emission spreads in all directions, leakage into adjacent pixels can be further suppressed by taking into consideration not only reflection from the metal trench 343 but also reflection from the wiring 321. In that case, as shown in Figures 20(A), 20(B), and 20(C), the optical film 354 may be adhered to the semiconductor layer surface, may be adhered to the wiring layer 321, or may be located between the semiconductor layer surface and the wiring layer 321. Also, it can be combined with each of the structural variations in Figures 19(A) to 19(E).

[0109] 21(A), 21(B), 21(C), and 21(D) show structural variations of the optical film 354 when the separation section 333 has two thickness stages in the depth direction.

[0110] In the case of the separation portion 333 having a two-stage thickness, if the optical film 354 is present on the sidewall of at least the first stage of the trench, the additional effect of the intended "suppression of leakage of avalanche emission light into adjacent pixels" can be obtained. However, the position of the optical film 354 in the separation portion 333 can be varied in various ways depending on the manufacturing order, one example of which is shown below.

[0111] FIG. 21(A) shows a structure in which the optical film 354 is in contact with the metal trench 343 up to the wiring structure 320. After trenches of different thicknesses are filled with an insulating film 352, a trench is formed in the insulating film 352 again, and the optical film 354 and the metal trench 343 are filled in, resulting in this structure. FIG. 21(B) shows a structure in which the optical film 354 is coated to conform to the shape of the separation section 333. After forming a trench with two thicknesses, the insulating film 352 and the optical film 354 are filled with a film with high coverage, and then filled with the insulating film 352 again, and the metal trench 343 is processed, resulting in this structure. FIG. 21(C) shows a structure in which the optical film 354 is coated to conform only to the trench shape of the first stage of the separation section 333. After the first trench is formed, the insulating film 352 and the optical film 354 are filled with a high coverage film, and then the second trench is formed and filled with the insulating film 352 and the metal trench 343, resulting in this structure. FIG. 21(D) shows a structure in which the optical film 354 is coated only on the sidewall of the first trench of the isolation section 333. After the first trench is formed, the insulating film 352 and the optical film 354 are filled with a high coverage film, the nitride film at the bottom of the trench is removed by etch-back, and then the second trench is formed and filled with the insulating film 352 and the metal trench 343, resulting in this structure. These variations can also be combined with the respective structural variations of FIGS. 19(A) to 19(E) and FIGS. 20(A) to 20(C).

[0112] 22(A), 22(B), and 22(C) show structural variations of the optical film 354 and the metal trench 343 when the separation portion 333 has two thickness stages in the depth direction and the thickness of the metal trench 343 is thicker in the first stage than in the second stage.

[0113] In the case of the separation portion 333 having a two-stage thickness, as long as the optical film 354 is present on the sidewall of at least the first stage of the trench, the additional effect of the intended "suppression of leakage of avalanche emission light into adjacent pixels" can be obtained even if the thickness of the metal trench 343 is changed. However, by making the thickness of the metal trench 343 thicker in the first stage, an additional effect of applying a potential directly from the metal trench 343 to the semiconductor layer 310 can be obtained, and an example of this is shown below.

[0114] FIG. 22(A) shows a structure in which an optical film 354 is coated to follow the shape of the separation portion 333. The manufacturing process can be simpler than that of FIG. 21(B), and such a structure is obtained by forming a trench with two thicknesses, then filling the insulating film 352 and the optical film 354 with a film with high coverage, and filling the metal trench 343. FIG. 22(B) shows a structure in which the metal trench 343 is connected to the semiconductor layer 310 at the bottom of the first trench and can apply a potential. As shown in FIG. 22(A) until the middle of the manufacturing process, after forming a trench with two thicknesses, the insulating film 352 and the optical film 354 are filled with a film with high coverage. After that, the silicon layer is reached by etch-back, and then the third semiconductor region 303 is formed by ion implantation such as self-alignment, and the metal trench 343 is filled, thereby obtaining such a structure. 22C shows a structure in which the trench from the first surface is only the first-stage trench, and the remaining semiconductor layer close to the second surface is connected with an insulating film 353, thereby obtaining the effect of suppressing a decrease in sensitivity as in the third embodiment. First, a trench is formed with the thickness of the first stage, and then the insulating film 352 and the optical film 354 are filled with a film with high coverage, and then etched back to reach the silicon layer. Then, a third semiconductor region 303 is formed by ion implantation such as self-alignment. Next, a trench is formed from the second surface so as to connect the remaining semiconductor layers, and is filled with an insulating film 353. At this time, by narrowing the trench from the second surface, it becomes possible to apply a potential while leaving the third semiconductor region 303. These variations can also be combined with the respective structural variations in Figures 19(A) to 19(E), Figures 20(A) to 20(C), and Figures 21(A) to 21(D).

[0115] Sixth embodiment 23(A) to 23(D), 24(A), and 24(B) show the structure of the sensor substrate 11 of the photoelectric conversion device according to the sixth embodiment. FIG. 23(A) is a plan view at a depth D1, which is the same depth as the first semiconductor region 301 in FIG. 24(A). FIG. 23(B) is a plan view at a depth D2, which is the same depth as the fourth semiconductor region 304 in FIG. 24(A). FIG. 23(C) is a plan view at a depth D3 located between the depth D2 and the second surface in FIG. 24(A). FIG. 23(D) is a plan view at a depth D4 where the optical film 354 at the bottom of the first stage trench in FIG. 24(A) exists. FIG. 24(A) is a cross-sectional view taken along the line AA (diagonal direction) in FIG. 23(A). FIG. 24(B) is a cross-sectional view taken along the line BB (opposite side direction) in FIG. 23(A). Hereinafter, a configuration different from the fifth embodiment will be described.

[0116] In the case of a separation section 333 having a two-stage thickness, if an optical film 354 is present on the side wall of at least the first stage of the trench, the desired additional effect of "suppressing leakage of avalanche emission light into adjacent pixels" can be obtained, as in this embodiment as well.

[0117] However, when etching the contact plugs, it is expected that rate control will be difficult because the etching rates are different between the optical film 354 and the insulating film 352. In this embodiment, the optical film 354 is not present in either the processing of the anode wiring contact plug 324 or the processing of the cathode wiring contact plug 326. Therefore, the etching rate of the contact plugs can be set under the constant rate condition of only the insulating film 352, making it easier to control the rate.

[0118] Seventh embodiment 25(A)-(D), 26(A), and 26(B) show the structure of the sensor substrate 11 of the photoelectric conversion device according to the seventh embodiment. FIG. 25(A) is a plan view at a depth D1 which is the same depth as the first semiconductor region 301 in FIG. 26(A). FIG. 25(B) is a plan view at a depth D2 which is the same depth as the fourth semiconductor region 304 in FIG. 26(A). FIG. 25(C) is a plan view at a depth D3 located between the depth D2 and the second surface in FIG. 26(A). FIG. 25(D) is a plan view at a depth D4 where the optical film 354 at the bottom of the first stage trench in FIG. 26(A) exists. FIG. 26(A) is a cross-sectional view taken along the line AA (diagonal direction) in FIG. 25(A). FIG. 26(B) is a cross-sectional view taken along the line BB (opposite side direction) in FIG. 25(A). Hereinafter, a configuration different from the sixth embodiment will be described.

[0119] The sixth embodiment is certainly the best in that it can reduce the difficulty of controlling the rate when etching the contact plug. However, it is inferior in that it takes into consideration the reflection of the avalanche light from the wiring 321, as described in the structural variation of Fig. 20. Therefore, the present embodiment is considered as the next best solution.

[0120] In this embodiment, a manufacturing method such as isotropic film formation is used. This results in a structure in which the film configuration from the optical film 354 to the semiconductor layer is the same in both etching processes for the anode wiring contact plug 324 and the cathode wiring contact plug 326. Therefore, the optical film 354 can be used as an etching stopper film, and the first etching stops at the optical film 354, and the second etching reaches the semiconductor layer. As a result, it is possible to reduce the difficulty of controlling the etching rate while also taking care of reflection from the wiring 321.

[0121] Eighth embodiment The photoelectric conversion system according to this embodiment will be described with reference to Fig. 27. Fig. 27 is a block diagram showing a schematic configuration of the photoelectric conversion system according to this embodiment.

[0122] The photoelectric conversion devices described in the first to seventh embodiments are applicable to various photoelectric conversion systems. The photoelectric conversion system includes at least the photoelectric conversion device according to the above embodiments and a signal processing unit that processes a signal output from the photoelectric conversion device. Examples of devices to which such photoelectric conversion systems can be applied include digital still cameras, digital camcorders, security cameras, copiers, fax machines, mobile phones, vehicle-mounted cameras, observation satellites, sensors, and measuring instruments. Camera modules equipped with an optical system such as a lens and an imaging device are also included in devices to which the photoelectric conversion system is applied. FIG. 27 illustrates a block diagram of a digital still camera as an example of these devices.

[0123] 27 includes an image pickup device 2704, which is an example of a photoelectric conversion device, and a lens 2702 that forms an optical image of a subject on the image pickup device 2704. The photoelectric conversion system also includes an aperture 2703 for varying the amount of light passing through the lens 2702, and a barrier 2701 for protecting the lens 2702. The lens 2702 and the aperture 2703 are an optical system that focuses light on the image pickup device 2704. The image pickup device 2704 is a photoelectric conversion device (image pickup device) according to any one of the above embodiments, and converts the optical image formed by the lens 2702 into an electrical signal.

[0124] The photoelectric conversion system also has a signal processing unit 2707 which is an image generating unit that generates an image by processing an output signal output from the imaging device 2704. The signal processing unit 2707 performs various corrections and compression as necessary to output image data. The signal processing unit 2707 may be formed on a semiconductor substrate on which the imaging device 2704 is provided, or may be formed on a semiconductor substrate separate from the imaging device 2704. Moreover, the imaging device 2704 and the signal processing unit 2707 may be formed on the same semiconductor substrate.

[0125] The photoelectric conversion system further includes a memory unit 2710 for temporarily storing image data, and an external interface unit (external I / F unit) 2713 for communicating with an external computer or the like. The photoelectric conversion system further includes a recording medium 2712 such as a semiconductor memory for recording or reading out imaging data, and a recording medium control interface unit (recording medium control I / F unit) 2711 for recording or reading out data on the recording medium 2712. The recording medium 2712 may be built into the photoelectric conversion system, or may be removable.

[0126] The photoelectric conversion system further includes an overall control / calculation unit 2709 that performs various calculations and controls the entire digital still camera, and a timing generation unit 2708 that outputs various timing signals to the image pickup device 2704 and the signal processing unit 2707. Here, the timing signals and the like may be input from outside, and the photoelectric conversion system only needs to include at least the image pickup device 2704 and the signal processing unit 2707 that processes the output signal output from the image pickup device 2704.

[0127] The imaging device 2704 outputs an imaging signal to the signal processing unit 2707. The signal processing unit 2707 performs predetermined signal processing on the imaging signal output from the imaging device 2704, and outputs image data. The signal processing unit 2707 generates an image using the imaging signal.

[0128] In this way, according to this embodiment, it is possible to realize a photoelectric conversion system to which the photoelectric conversion device (imaging device) according to any one of the above embodiments is applied.

[0129] Ninth embodiment The photoelectric conversion system and the moving object of this embodiment will be described with reference to Fig. 28(A) and Fig. 28(B). Fig. 28(A) is a diagram showing the configuration of the photoelectric conversion system of this embodiment, and Fig. 28(B) is a diagram showing the configuration of the moving object of this embodiment.

[0130] FIG. 28(A) shows an example of a photoelectric conversion system related to an in-vehicle camera. The photoelectric conversion system 2800 has an image capture device 2810. The image capture device 2810 is the photoelectric conversion device (image capture device) described in any of the above embodiments. The photoelectric conversion system 2800 has an image processing unit 2812 that performs image processing on a plurality of image data acquired by the image capture device 2810. The photoelectric conversion system 2800 also has a distance acquisition unit 2816 that calculates a distance to an object, and a collision determination unit 2818 that determines whether or not there is a possibility of collision based on the calculated distance. Here, the distance acquisition unit 2816 may acquire distance information to the object using ToF (Time Of Flight), or may acquire distance information using parallax information or the like. That is, the distance information is information related to parallax, defocus amount, distance to the object, and the like. The collision determination unit 2818 may determine the possibility of collision using any of these distance information. The distance information acquisition means may be realized by dedicated hardware or may be realized by a software module. It may also be realized by a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or the like, or may be realized by a combination of these.

[0131] The photoelectric conversion system 2800 is connected to a vehicle information acquisition device 2820, and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The photoelectric conversion system 2800 is also connected to an ECU 2830, which is a control device that outputs a control signal to generate a braking force for the vehicle based on the judgment result of the collision judgment unit 2818. The photoelectric conversion system 2800 is also connected to an alarm device 2840 that issues an alarm to the driver based on the judgment result of the collision judgment unit 2818. For example, when the judgment result of the collision judgment unit 2818 indicates that there is a high possibility of a collision, the ECU 2830 performs vehicle control to avoid a collision and reduce damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. The alarm device 2840 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.

[0132] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are imaged by the photoelectric conversion system 2800. Fig. 28(B) shows the photoelectric conversion system when imaging the area in front of the vehicle (imaging range 2850). A vehicle information acquisition device 2820 sends an instruction to the photoelectric conversion system 2800 or the imaging device 2810. With this configuration, the accuracy of distance measurement can be further improved.

[0133] Although an example of control to avoid collision with other vehicles has been described above, the present invention can also be applied to control of automatic driving by following other vehicles, control of automatic driving to avoid going out of a lane, and the like. Furthermore, the photoelectric conversion system is not limited to vehicles such as automobiles, but can be applied to moving bodies (moving devices) such as ships, aircraft, and industrial robots. The moving body includes one or both of a driving force generating unit that generates a driving force mainly used for the movement of the moving body, and a rotating body mainly used for the movement of the moving body. The driving force generating unit can be an engine, a motor, and the like. The rotating body can be a tire, a wheel, a screw of a ship, a propeller of an aircraft, and the like. In addition, the present invention can be applied not only to moving bodies, but also to a wide range of devices that use object recognition, such as an intelligent transport system (ITS).

[0134] Tenth embodiment The photoelectric conversion system of this embodiment will be described with reference to Fig. 29. Fig. 29 is a block diagram showing an example of the configuration of a range image sensor which is the photoelectric conversion system of this embodiment.

[0135] 29, distance image sensor 2901 is configured to include an optical system 2907, a photoelectric conversion device 2908, an image processing circuit 2904, a monitor 2905, and a memory 2906. The distance image sensor 2901 can obtain a distance image according to the distance to the subject by receiving light (modulated light or pulsed light) that is projected from a light source device 2909 toward the subject and reflected from the surface of the subject.

[0136] The optical system 2907 is configured to have one or more lenses, and guides image light (incident light) from a subject to a photoelectric conversion device 2908 , forming an image on the light receiving surface (sensor portion) of the photoelectric conversion device 2908 .

[0137] As the photoelectric conversion device 2908 , the photoelectric conversion device of each of the above-mentioned embodiments is applied, and a distance signal indicating a distance determined from a light receiving signal output from the photoelectric conversion device 2908 is supplied to the image processing circuit 2904 .

[0138] The image processing circuit 2904 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric conversion device 2908. The distance image (image data) obtained by this image processing is then supplied to a monitor 2905 for display, or supplied to a memory 2906 for storage (recording).

[0139] In the range image sensor 2901 configured in this way, by applying the above-mentioned photoelectric conversion device, it is possible to obtain, for example, a more accurate range image as the pixel characteristics improve.

[0140] Eleventh embodiment The photoelectric conversion system of this embodiment will be described with reference to Fig. 30. Fig. 30 is a diagram showing an example of a schematic configuration of an endoscopic surgery system which is the photoelectric conversion system of this embodiment.

[0141] 30 shows a state in which an operator (doctor) 3031 is performing surgery on a patient 3032 on a patient bed 3033 using an endoscopic surgery system 3050. As shown in the figure, the endoscopic surgery system 3050 is composed of an endoscope 3000, a surgical tool 3010, and a cart 3034 on which various devices for endoscopic surgery are mounted.

[0142] The endoscope 3000 is composed of a lens barrel 3001, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 3032, and a camera head 3002 connected to the base end of the lens barrel 3001. In the illustrated example, the endoscope 3000 is configured as a so-called rigid lens barrel having a rigid lens barrel 3001, but the endoscope 3000 may be configured as a so-called flexible lens barrel having a flexible lens barrel.

[0143] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 3001. A light source device 3003 is connected to the endoscope 3000, and light generated by the light source device 3003 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 3001, and is irradiated via the objective lens toward an observation target in a body cavity of a patient 3032. The endoscope 3000 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0144] An optical system and a photoelectric conversion device are provided inside the camera head 3002, and the reflected light (observation light) from the observation object is collected on the photoelectric conversion device by the optical system. The observation light is photoelectrically converted by the conversion device, and an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image, is generated. As the photoelectric conversion device, the photoelectric conversion device (imaging device) described in each of the above-mentioned embodiments can be used. The image signal is transmitted to a camera control unit (CCU: Camera Control Unit) 3035 as RAW data.

[0145] The CCU 3035 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and performs overall control of the operations of the endoscope 3000 and the display device 3036. Furthermore, the CCU 3035 receives an image signal from the camera head 3002, and performs various types of image processing on the image signal, such as development processing (demosaic processing), for displaying an image based on the image signal.

[0146] Under the control of the CCU 3035 , the display device 3036 displays an image based on an image signal that has been subjected to image processing by the CCU 3035 .

[0147] The light source device 3003 is composed of a light source such as an LED (Light Emitting Diode), and supplies the endoscope 3000 with irradiation light when photographing an operation site or the like.

[0148] The input device 3037 is an input interface for the endoscopic surgery system 3050. A user can input various information and instructions to the endoscopic surgery system 3050 via the input device 3037.

[0149] The treatment tool control device 3038 controls the driving of the energy treatment tool 3012 for cauterizing tissue, incising, sealing blood vessels, or the like.

[0150] The light source device 3003 that supplies irradiation light to the endoscope 3000 when photographing the surgical site can be composed of a white light source composed of, for example, an LED, a laser light source, or a combination of these. When the white light source is composed of a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so that the white balance of the captured image can be adjusted in the light source device 3003. In this case, it is also possible to capture images corresponding to each of the RGB colors in a time-division manner by irradiating the observation target with laser light from each of the RGB laser light sources in a time-division manner and controlling the driving of the image sensor of the camera head 3002 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.

[0151] Furthermore, the light source device 3003 may be controlled to change the intensity of the light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 3002 in synchronization with the timing of the change in the light intensity to acquire images in a time-division manner and synthesizing the images, it is possible to generate an image with a high dynamic range that is free of so-called blocked-up shadows and blown-out highlights.

[0152] Furthermore, the light source device 3003 may be configured to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, the wavelength dependency of light absorption in body tissue is utilized. Specifically, a predetermined tissue such as blood vessels on the mucosal surface is photographed with high contrast by irradiating light with a narrower band than the light (i.e., white light) irradiated during normal observation. Alternatively, in special light observation, fluorescent observation may be performed in which an image is obtained from fluorescence generated by irradiating excitation light. In fluorescent observation, excitation light is irradiated onto body tissue and the fluorescence from the body tissue is observed, or a reagent such as indocyanine green (ICG) is locally injected into the body tissue and excitation light corresponding to the fluorescent wavelength of the reagent is irradiated onto the body tissue to obtain a fluorescent image, etc. The light source device 3003 can be configured to be capable of supplying narrowband light and / or excitation light compatible with such special light observation.

[0153] Twelfth embodiment The photoelectric conversion system of this embodiment will be described with reference to Figs. 31(A) and 31(B). Fig. 31(A) describes glasses 3100 (smart glasses) which are the photoelectric conversion system of this embodiment. The glasses 3100 have a photoelectric conversion device 3102. The photoelectric conversion device 3102 is the photoelectric conversion device (imaging 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 3101. The photoelectric conversion device 3102 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 3102 is not limited to that shown in Fig. 31(A).

[0154] The glasses 3100 further include a control device 3103. The control device 3103 functions as a power source that supplies power to the photoelectric conversion device 3102 and the display device. The control device 3103 also controls the operations of the photoelectric conversion device 3102 and the display device. The lens 3101 is formed with an optical system for focusing light on the photoelectric conversion device 3102.

[0155] FIG. 31(B) illustrates glasses 3110 (smart glasses) according to one application example. The glasses 3110 have a control device 3112, and the control device 3112 is equipped with a photoelectric conversion device corresponding to the photoelectric conversion device 3102 and a display device. The lens 3111 is formed with an optical system for projecting light emitted from the photoelectric conversion device in the control device 3112 and the display device, and an image is projected onto the lens 3111. The control device 3112 functions as a power source for supplying 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 have a line of sight detection unit that detects the line of sight of the wearer. Infrared light may be used for detecting the line of sight. The infrared light emitting unit emits infrared light toward the eyeball of a user gazing at a display image. An imaging unit having a light receiving element detects the reflected light of the emitted infrared light from the eyeball, thereby obtaining an image of the eyeball. By having a reduction means for reducing light from the infrared light emitting unit to the display unit in a planar view, deterioration of image quality is reduced.

[0156] The gaze of the user 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 the 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.

[0157] More specifically, the gaze detection process is performed based on the pupil-corneal reflex method. Using the pupil-corneal reflex method, a gaze vector that indicates the direction (rotation angle) of the eyeball is calculated based on the pupil image and the Purkinje image included in the captured image of the eyeball, thereby detecting the user's gaze.

[0158] The display device of this embodiment may have a photoelectric conversion device having a light receiving element, and may control the display image of the display device based on information about the user's line of sight from the photoelectric conversion device.

[0159] Specifically, the display device determines a first field of view area to which 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 received from an external control device. 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.

[0160] The display area includes a first display area and a second display area different from the first display area. Then, a high priority area may be determined from the first display area and the second display area based on the line-of-sight information. The first display area and the second display 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.

[0161] In addition, AI may be used to determine the first field of view area and the area with high priority. The AI ​​may be a model configured to estimate the angle of the line of sight and the distance to an object at the end of the line of sight from the image of the eyeball, using the image of the eyeball and the direction in which the eyeball in the image was actually looking as teacher data. The AI ​​program may be included in the display device, the photoelectric conversion device, or an external device. If included in the external device, it is transmitted to the display device via communication.

[0162] When display control is performed based on visual recognition detection, the present invention can be preferably applied to smart glasses further including a photoelectric conversion device for capturing an image of the outside world. The smart glasses can display captured outside information in real time.

[0163] Thirteenth embodiment The above-described photoelectric conversion device and photoelectric conversion system may be applied to electronic devices such as so-called smartphones and tablets.

[0164] Fig. 32(A) and Fig. 32(B) are diagrams showing an example of an electronic device 3200 equipped with a photoelectric conversion device. Fig. 32(A) shows the front side of the electronic device 3200, and Fig. 32(B) shows the rear side of the electronic device 3200.

[0165] 32(A), a display 3210 for displaying an image is disposed in the center of the surface of the electronic device 3200. Then, along the upper side of the surface of the electronic device 3200, front cameras 3221 and 3222 using photoelectric conversion devices, an IR light source 3230 for emitting infrared light, and a visible light source 3240 for emitting visible light are disposed.

[0166] Also, as shown in FIG. 32(B), rear cameras 3251 and 3252 using photoelectric conversion devices, an IR light source 3260 that emits infrared light, and a visible light source 3270 that emits visible light are arranged along the upper edge of the back surface of the electronic device 3200.

[0167] In the electronic device 3200 configured in this manner, by applying the above-mentioned photoelectric conversion device, for example, it is possible to capture a higher quality image. Note that the photoelectric conversion device can also be applied to other electronic devices such as infrared sensors, distance measuring sensors using active infrared light sources, security cameras, and personal or biometric authentication cameras. This can improve the accuracy, performance, and the like of these electronic devices.

[0168] Fourteenth embodiment 33 is a block diagram of the X-ray CT device in this embodiment. The above-mentioned photoelectric conversion device and photoelectric conversion system are applicable to the detector of the X-ray CT device. The X-ray CT device 3300 in this embodiment includes an X-ray generation unit 3310, a wedge 3311, a collimator 3312, an X-ray detection unit 3320, and a tabletop 3330. The X-ray CT device 3300 further includes a rotating frame 3340, a high-voltage generator 3350, a data acquisition system (DAS) 3351, a signal processing unit 3352, a display unit 3353, and a control unit 3354.

[0169] The X-ray generating unit 3310 is composed of, for example, a vacuum tube that generates X-rays. A high voltage and a filament current are supplied from a high voltage generator 3350 to the vacuum tube of the X-ray generating unit 3310. X-rays are generated when thermal electrons are emitted from the cathode (filament) to the anode (target).

[0170] The wedge 3311 is a filter that adjusts the amount of X-rays irradiated from the X-ray generating unit 3310. The wedge 3311 attenuates the amount of X-rays so that the X-rays irradiated from the X-ray generating unit 3310 to the subject have a predetermined distribution. The collimator 3312 is made of a lead plate or the like that narrows down the irradiation range of the X-rays that have passed through the wedge 3311. The X-rays generated by the X-ray generating unit 3310 are shaped into a cone beam via the collimator 3312 and irradiated to the subject on the tabletop 3330.

[0171] The X-ray detection unit 3320 is configured using the above-mentioned photoelectric conversion device or photoelectric conversion system. The X-ray detection unit 3320 detects X-rays emitted from the X-ray generation unit 3310 and transmitted through the subject, and outputs a signal corresponding to the X-ray dose to the DAS 3351.

[0172] The rotating frame 3340 has an annular shape and is configured to be rotatable. An X-ray generation unit 3310 (wedge 3311, collimator 3312) and an X-ray detection unit 3320 are arranged facing each other inside the rotating frame 3340. The X-ray generation unit 3310 and the X-ray detection unit 3320 are rotatable together with the rotating frame 3340.

[0173] The high voltage generator 3350 includes a boost circuit, and outputs a high voltage to the X-ray generating unit 3310. The DAS 3351 includes an amplifier circuit and an A / D conversion circuit, and outputs a signal from the X-ray detecting unit 3320 to the signal processing unit 3352 as digital data.

[0174] The signal processing unit 3352 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and can perform image processing on digital data. The display unit 3353 includes a flat display device, and can display X-ray images. The control unit 3354 includes a CPU, a ROM, a RAM, and controls the operation of the entire X-ray CT device 3300.

[0175] Fifteenth embodiment A photoelectric conversion system according to the 15th embodiment will be described with reference to Fig. 34. Fig. 34 is a block diagram showing a schematic configuration of an imaging system SYS, which is a photoelectric conversion system according to the 15th embodiment. The imaging system SYS includes at least a photoelectric conversion device according to any of the above embodiments, and a signal processing unit that processes a signal output from the photoelectric conversion device.

[0176] The imaging system SYS is an information terminal having a camera and a photographing function. The imaging system SYS is constructed using an imaging device IS. The imaging device IS may further include a package PKG that houses an imaging device IC. The package PKG may include a base to which the imaging device IC is fixed, and a lid that faces the imaging device IC. The package PKG may include a connection member (a member that connects a terminal provided on the base with a terminal provided on the imaging device IC). The imaging device IS may also mount a plurality of imaging device ICs side by side in a common package PKG. Also, the imaging device IS may also mount an imaging device IC and another semiconductor device IC stacked on top of each other in a common package PKG.

[0177] The imaging system SYS may include an optical system OU (optical device) that forms an image on the imaging device IS. The imaging system SYS may also include at least one of a control device CU, a processing device PU, a display device DU, and a storage device MU. The control device CU controls the imaging device IS, and the processing device PU processes signals obtained from the imaging device IS. The display device DU displays images obtained from the imaging device IS, and the storage device MU stores images obtained from the imaging device IS.

[0178] (others) Although various devices have been described in the above embodiment, a mechanical device may be further provided. The mechanical device in the camera can drive optical components for zooming, focusing, and shutter operation. Alternatively, the mechanical device in the camera can move a photoelectric conversion device for vibration reduction operation.

[0179] The device may be transportation equipment such as a vehicle, ship, or aircraft. A mechanical device in transportation equipment may be used as a moving device. The device as transportation equipment is suitable for transporting a photoelectric conversion device or for assisting and / or automating driving (piloting) by using an imaging function. A processing device for assisting and / or automating driving (piloting) can perform processing for operating the mechanical device as a moving device based on information obtained by the photoelectric conversion device.

[0180] The above-described embodiments can be modified as appropriate without departing from the technical concept. The disclosure of this specification includes not only what is described in this specification, but also all matters that can be understood from this specification and the drawings attached hereto. The disclosure of this specification also includes the complement of the concepts described in this specification. In other words, if this specification contains a statement that "A is greater than B," for example, this specification can be said to disclose that "A is not greater than B" even if the statement that "A is not greater than B" is omitted. This is because when it is stated that "A is greater than B," it is assumed that the case in which "A is not greater than B" is taken into consideration.

[0181] In the present specification, expressions such as "A or B", "at least one of A and B", "at least one of A or / and B", "one or more of A or / and B" may be used. In this case, unless otherwise expressly defined, all possible combinations of the listed items can be included. That is, the above expressions are understood to disclose all cases including at least one A, at least one B, and both at least one A and at least one B. This applies equally to combinations of three or more elements.

[0182] The disclosure of this embodiment includes the following configuration. (Configuration 1) a substrate having a first surface and a second surface facing the first surface and serving as a light incidence surface; a plurality of photoelectric conversion elements provided on the substrate, each of the photoelectric conversion elements including an avalanche photodiode; a separator that separates the plurality of photoelectric conversion elements; having each of the plurality of photoelectric conversion elements includes a first semiconductor region of a first conductivity type to which a first potential is applied and which constitutes the avalanche photodiode, and a second semiconductor region of a second conductivity type which constitutes the avalanche photodiode; the separation unit includes a conductor to which a second potential different from the first potential is applied, and an insulator provided between the photoelectric conversion element and the conductor; In a direction parallel to the first surface, a thickness of the insulator at a first depth that is the same depth as the first semiconductor region is greater than a thickness of the insulator at a third depth located between a second depth that is the same depth as the second semiconductor region and the second surface. A photoelectric conversion device comprising: (Configuration 2) a substrate having a first surface and a second surface facing the first surface and serving as a light incidence surface; a first photoelectric conversion element provided on the substrate, each of the first photoelectric conversion elements including an avalanche photodiode; and a second photoelectric conversion element; a separator located between the first photoelectric conversion element and the second photoelectric conversion element and separating at least the first surface side; A first wiring layer disposed on the first surface side of the substrate; having the separation portion includes a conductor, a first insulator, and a second insulator, the first insulator and the second insulator are disposed between the conductor and the first photoelectric conversion element; The refractive index of the second insulator is higher than that of the first insulator, The second insulator extends to the first wiring layer. A photoelectric conversion device comprising: (Configuration 3) In a direction parallel to the first surface, a thickness of the insulator at the first depth is greater than a thickness of the insulator at the second depth. 2. The photoelectric conversion device according to configuration 1. (Configuration 4) a third semiconductor region of the second conductivity type surrounding the insulator; In a direction parallel to the first surface, the thickness of the insulator at the first depth is greater than a sum of a thickness of the third semiconductor region and the thickness of the insulator at the third depth. 4. The photoelectric conversion device according to configuration 3. (Configuration 5) The insulator is provided so as to surround the conductor. 5. The photoelectric conversion device according to any one of configurations 1, 3 and 4. (Configuration 6) The conductor is at the first depth and is not at the third depth. 6. The photoelectric conversion device according to any one of configurations 1, 3 to 5. (Configuration 7) The semiconductor device further includes an anode electrode provided on the second surface side. 7. The photoelectric conversion device according to any one of configurations 1, 3 to 6. (Configuration 8) The conductor also serves as an anode electrode. 7. The photoelectric conversion device according to any one of configurations 1, 3 to 6. (Configuration 9) A photoelectric conversion device according to any one of configurations 1 to 8, a signal processing unit that generates an image using a signal output from the photoelectric conversion device; A photoelectric conversion system comprising: (Configuration 10) A moving object including the photoelectric conversion device according to any one of configurations 1 to 8, A moving body comprising: a control unit that controls the movement of the moving body using a signal output from the photoelectric conversion device. (Configuration 11) A photoelectric conversion device according to any one of configurations 1 to 8, an optical device corresponding to the photoelectric conversion device; A control device for controlling the photoelectric conversion device; a processing device that processes a signal output from the photoelectric conversion device; a display device that displays information obtained by the photoelectric conversion device; a storage device that stores information obtained by the photoelectric conversion device; and a mechanical device that operates based on information obtained by the photoelectric conversion device; At least one of An apparatus comprising: [Explanation of symbols]

[0183] 201: APD 102: photoelectric conversion element 331: separation section 301: first semiconductor region 304: fourth semiconductor region 341: metal trench 351: insulating film

Claims

1. a substrate having a first surface and a second surface facing the first surface and serving as a light incidence surface; a plurality of photoelectric conversion elements provided on the substrate, each of the photoelectric conversion elements including an avalanche photodiode; a separator that separates the plurality of photoelectric conversion elements; having each of the plurality of photoelectric conversion elements includes a first semiconductor region of a first conductivity type to which a first potential is applied and which constitutes the avalanche photodiode, and a second semiconductor region of a second conductivity type which constitutes the avalanche photodiode; the isolation portion includes a conductor to which a second potential different from the first potential is applied, and an insulator provided between the photoelectric conversion element and the conductor; In a direction parallel to the first surface, a thickness of the insulator at a first depth that is the same depth as the first semiconductor region is greater than a thickness of the insulator at a third depth located between a second depth that is the same depth as the second semiconductor region and the second surface. A photoelectric conversion device comprising:

2. a substrate having a first surface and a second surface facing the first surface and serving as a light incidence surface; a first photoelectric conversion element and a second photoelectric conversion element provided on the substrate, each of the first photoelectric conversion element and the second photoelectric conversion element including an avalanche photodiode; a separator located between the first photoelectric conversion element and the second photoelectric conversion element and separating at least the first surface side; a first wiring layer disposed on the first surface side of the substrate; having the separation portion includes a conductor, a first insulator, and a second insulator, the first insulator and the second insulator are disposed between the conductor and the first photoelectric conversion element; The refractive index of the second insulator is higher than that of the first insulator, The second insulator extends to the first wiring layer. A photoelectric conversion device comprising:

3. In a direction parallel to the first surface, a thickness of the insulator at the first depth is greater than a thickness of the insulator at the second depth.

2. The photoelectric conversion device according to claim 1.

4. a third semiconductor region of the second conductivity type surrounding the insulator; In a direction parallel to the first surface, the thickness of the insulator at the first depth is greater than a sum of a thickness of the third semiconductor region and the thickness of the insulator at the third depth.

4. The photoelectric conversion device according to claim 3.

5. The insulator is provided so as to surround the conductor.

2. The photoelectric conversion device according to claim 1.

6. The conductor is at the first depth and is not at the third depth.

2. The photoelectric conversion device according to claim 1.

7. The semiconductor device further includes an anode electrode provided on the second surface side.

2. The photoelectric conversion device according to claim 1.

8. The conductor also serves as an anode electrode.

2. The photoelectric conversion device according to claim 1.

9. The photoelectric conversion device according to any one of claims 1 to 8, a signal processing unit that generates an image using a signal output from the photoelectric conversion device; A photoelectric conversion system comprising:

10. A moving object comprising the photoelectric conversion device according to any one of claims 1 to 8, A moving body comprising: a control unit that controls the movement of the moving body using a signal output from the photoelectric conversion device.

11. The photoelectric conversion device according to any one of claims 1 to 8, an optical device corresponding to the photoelectric conversion device; A control device for controlling the photoelectric conversion device; a processing device that processes a signal output from the photoelectric conversion device; a display device that displays information obtained by the photoelectric conversion device; a storage device that stores information obtained by the photoelectric conversion device; and a mechanical device that operates based on information obtained by the photoelectric conversion device; At least one of An apparatus comprising:

Images