Photoelectric conversion device, photoelectric conversion system, movable body, and apparatus

Abstract

To prevent crosstalk that is caused by light generated by avalanche multiplication.SOLUTION: A photoelectric conversion device having a plurality of pixels has: an avalanche multiplication area where avalanche multiplication is performed; pixel separation in which the pixels are separated from each other and an oxide film is formed; a light-shielding film that is a film at least partially overlapping the pixel separation in plan view and that blocks light; and a reflecting member that is formed in contact with the pixel separation and the light-shielding film between the pixel separation and the light-shielding film, and surrounds the periphery of one pixel in plan view.SELECTED DRAWING: Figure 6

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 also disclosed that an avalanche diode (APD) in which electric charge undergoes avalanche multiplication is used for the pixels in the sensor chip of this photoelectric conversion device. Patent Document 1 also discloses that a light shielding film is disposed to reduce the amount of incident light that is incident on pixels other than the one to which it should be incident. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-167249 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, there is a possibility that light generated by avalanche multiplication in one pixel may be reflected by the light-shielding film, as shown in the optical path 701 in Fig. 7. This may cause crosstalk, as the light generated by avalanche multiplication may enter other pixels.

[0005] Therefore, an object of the present invention is to suppress crosstalk caused by light generated by avalanche multiplication. [Means for solving the problem]

[0006] One aspect of the present invention is a method for producing a composition comprising the steps of: A photoelectric conversion device having a plurality of pixels, an avalanche multiplication region in which avalanche multiplication takes place; a pixel separator that separates pixels and has an oxide film formed thereon; a light-shielding film that at least partially overlaps the pixel isolation in a plan view and that blocks light; a reflective member that is formed between the pixel isolation and the light-shielding film so as to be in contact with the pixel isolation and the light-shielding film and that surrounds one pixel in a plan view; The photoelectric conversion device is characterized by having the following features. Effect of the Invention

[0007] According to the present invention, crosstalk caused by light generated by avalanche multiplication can be suppressed. [Brief description of the drawings]

[0008] [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] 1 is a cross-sectional view of a photoelectric conversion element according to a first embodiment. [Figure 7] FIG. 4 is a cross-sectional view of a photoelectric conversion element according to a comparative example of the first embodiment. [Figure 8] 2 is a cross-sectional view taken along the line AA′ according to the first embodiment. FIG. [Figure 9] 5A to 5C are diagrams illustrating the widths of a reflective member and a light-shielding film according to the first embodiment. [Figure 10] FIG. 4 is a cross-sectional view of a photoelectric conversion element according to a second embodiment. [Figure 11] FIG. 11 is a cross-sectional view of a photoelectric conversion element according to a third embodiment. [Figure 12] FIG. 13 is a diagram illustrating a photoelectric conversion system according to a fourth embodiment. [Figure 13] FIG. 13 is a diagram illustrating a photoelectric conversion system and a moving object according to a fifth embodiment. [Figure 14] 13A to 13C are diagrams illustrating a range image sensor according to a sixth embodiment. [Figure 15] 13A to 13C are diagrams illustrating an endoscopic surgery system according to a seventh embodiment. [Figure 16] FIG. 13 is a diagram illustrating smart glasses according to an eighth embodiment. [Figure 17] FIG. 13 is a diagram illustrating an electronic device according to a ninth embodiment. [Figure 18] FIG. 23 is a diagram illustrating an X-ray CT apparatus according to a tenth embodiment. [Figure 19] FIG. 23 is a diagram illustrating a photoelectric conversion system according to an eleventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 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.

[0010] 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.

[0011] In this specification, a planar view refers to a view from a direction perpendicular to the light incident surface of the semiconductor layer (viewed from the stacking direction of the semiconductor layer). A cross-sectional view refers to a view from a direction perpendicular to the light incident surface of the semiconductor layer. When the light incident surface of the semiconductor layer is a rough surface when viewed microscopically, the planar view is defined based on the light incident surface of the semiconductor layer when viewed macroscopically.

[0012] 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."

[0013] 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 charges of the same polarity as the signal charge are the majority carriers is an N-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 a P-type semiconductor region. Note that the present invention also applies when the cathode of the APD is set to a fixed potential, and the signal is taken 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. The semiconductor region is a P-type semiconductor region, and the second conductivity type semiconductor region, which has charges of a polarity opposite to the signal charges as majority carriers, is an N-type semiconductor region. In the following, a case will be described in which one node of the APD is at a fixed potential, but the potentials of both nodes may fluctuate.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] The sensor substrate 11 has a first semiconductor layer having a photoelectric conversion element 102 described later, and a first wiring structure. The circuit substrate 21 has a second semiconductor layer having circuits such as a signal processing unit 103 described later. The photovoltaic device 100 has a second semiconductor layer, a second wiring structure, a first wiring structure, and a first semiconductor layer stacked in this order.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] The control pulse generating unit 115 has a signal generating unit 215 that generates a control signal P_CLK for the 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 A common control signal P_CLK may be generated for a plurality of pixels in the pixel region, or a control signal P_CLK may be generated for each pixel as shown in FIG. 4(B). When a common control signal P_CLK is generated, at least one of the period, the number of pulses, and the pulse width of a signal P_EXP (pulse signal) that controls the exposure period is generated in common in correspondence with the exposure period. When a control signal P_CLK is controlled for each pixel, a signal can be generated using both an input signal P_CLK_IN output from the control pulse generating unit 115 and a 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 reduces an increase in the number of elements.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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 .

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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 functions as a load circuit (quenching circuit) during signal multiplication by avalanche multiplication, and has a function of suppressing avalanche multiplication by suppressing the voltage supplied to the APD 201 (quenching operation). In addition, the switch The switch 202 has a function of returning the voltage supplied to the APD 201 to the drive voltage VH by passing 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 for controlling the occurrence of avalanche multiplication in the APD 201.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] In contrast, by applying a control signal P_CLK to the switch 202 to switch the switch 202 between an on state and an off state, it is possible to determine a signal even when photons continuously enter the APD 201 in a short period of time. In FIG. 5, an example is described in which the control signal P_CLK is a pulse signal with a repetitive cycle. In other words, in FIG. 5, a form is described 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 can be obtained even if the pulse signal is not a signal with a repetitive cycle.

[0046] 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.

[0047] A control pulse pSEL is supplied to the selection circuit 212 from the vertical scanning circuit unit 110 in Fig. 3 via a drive line 214 (not shown in Fig. 3) 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.

[0048] 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.

[0049] 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 be configured to 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.

[0050] 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.

[0051] 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.

[0052] 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 high. Then, the potential difference between the potentials applied to the anode and cathode of the APD 201 becomes a state in which avalanche multiplication is possible. The potential of the cathode is the same as that of the node nodeA. Therefore, when the potential of the cathode changes from low to high, When the potential of the node A transitions from high level to low level at time t2, the potential of the node A becomes equal to or higher than the decision threshold. At this time, the pulse signal output from the node B is inverted and goes from high level to low level. After that, the potential difference of the drive voltage VH-drive voltage VL is applied to the APD 201. The control signal P_CLK goes high level, and the switch is turned off.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] The photoelectric conversion devices of the respective embodiments will be described below.

[0058] (First embodiment) The photoelectric conversion element 102 in the photoelectric conversion device according to the first embodiment will be described with reference to FIG. 6 to FIG. 9(C).

[0059] FIG. 6 is a cross-sectional view of two pixels of the photoelectric conversion element 102 according to the first embodiment, viewed in a direction perpendicular to the surface direction of the substrate.

[0060] The structure and function of the photoelectric conversion element 102 will be described. The semiconductor layer 301 of the photoelectric conversion element 102 has a first semiconductor region 311 of N type, a fourth semiconductor region 314, a sixth semiconductor region 316, and a seventh semiconductor region 317. The semiconductor layer 301 of the photoelectric conversion element 102 further includes a second semiconductor region 312, a third semiconductor region 313, and a fifth semiconductor region 315 of P type.

[0061] In the first embodiment, in the cross section shown in FIG. 6, an N-type first semiconductor region 311 is formed in the vicinity of the first surface. An N-type seventh semiconductor region 317 is formed around the first semiconductor region 311. A P-type second semiconductor region 312 is formed at a position overlapping the first semiconductor region 311 and the seventh semiconductor region 317 in a planar view. An N-type fourth semiconductor region 314 is disposed at a position overlapping the second semiconductor region 312 in a planar view. Around the fourth semiconductor region 314 An N-type sixth semiconductor region 316 is formed.

[0062] The first semiconductor region 311 has a higher N-type impurity concentration than the fourth semiconductor region 314 and the seventh semiconductor region 317. A PN junction is formed between the P-type second semiconductor region 312 and the N-type first semiconductor region 311. By making the impurity concentration of the second semiconductor region 312 lower than that of the first semiconductor region 311, the entire region of the second semiconductor region 312 becomes a depletion layer region. Furthermore, this depletion layer region extends to a partial region of the first semiconductor region 311, and a strong electric field is induced in the extended depletion layer region. This strong electric field causes avalanche multiplication in the depletion layer region extending to a partial region of the first semiconductor region 311, and a current based on the amplified charge is output as a signal charge. When light incident on the photoelectric conversion element 102 is photoelectrically converted and avalanche multiplication occurs in this depletion layer region (avalanche multiplication region), the generated first conductivity type charge is collected in the first semiconductor region 311.

[0063] Furthermore, when avalanche multiplication occurs, avalanche emission occurs in the pixel (avalanche multiplication region), which can cause the APD in the adjacent pixel to malfunction. Avalanche emission is a phenomenon in which light is emitted when some of the large number of electrons recombine with holes in the semiconductor layer. The light caused by avalanche emission (avalanche light) can leak into adjacent pixels and cause crosstalk. Crosstalk caused by avalanche light is called "avalanche crosstalk (avalanche color mixing)."

[0064] 6, the fourth semiconductor region 314 and the seventh semiconductor region 317 are formed to have approximately the same size, but the size of each semiconductor region is not limited to this. For example, the fourth semiconductor region 314 may be formed to be larger than the seventh semiconductor region 317 so that charges are collected in the first semiconductor region 311 from a wider range.

[0065] A trench-based uneven structure 325 is formed on the second surface (surface on the second surface side) of the semiconductor layer 301 (photoelectric conversion element 102). The uneven structure 325 is surrounded by a P-type third semiconductor region 313, and scatters light incident on the photoelectric conversion element 102. Since the incident light travels obliquely inside the photoelectric conversion element 102, an optical path length equal to or greater than the thickness of the semiconductor layer 301 can be ensured, and light with a longer wavelength can be photoelectrically converted compared to a case in which the uneven structure 325 is not provided. In addition, the uneven structure 325 prevents the incident light from being reflected within the substrate, and thus an effect of improving the photoelectric conversion efficiency of the incident light is obtained. Since the uneven structure 325 is not an essential component, the photoelectric conversion element 102 does not need to have the uneven structure 325.

[0066] The fourth semiconductor region 314 and the uneven structure 325 are formed so as to overlap in a plan view. The area where the fourth semiconductor region 314 and the uneven structure 325 overlap in a plan view is larger than the area of ​​the portion of the fourth semiconductor region 314 that does not overlap with the uneven structure 325. Charges generated at a position far from the avalanche multiplication region (a region formed between the first semiconductor region 311 and the fourth semiconductor region 314) take longer to travel to the avalanche multiplication region than charges generated at a position close to the avalanche multiplication region. This may worsen timing jitter. By arranging the fourth semiconductor region 314 and the uneven structure 325 at a position where they overlap in a plan view, the electric field deep in the photodiode can be increased, and the collection time of charges generated at a position far from the avalanche multiplication region can be shortened. This makes it possible to reduce timing jitter.

[0067] Furthermore, the third semiconductor region 313 three-dimensionally covers the concave-convex structure 325, thereby making it possible to suppress the generation of thermally excited charges at the interface of the concave-convex structure 325. This suppresses the DCR (Dark Count Rate) of the photoelectric conversion element 102.

[0068] Between pixels (between pixels) is a pixel isolation section 324 (element isolation) having a trench structure. It is separated. Here, in the first embodiment, the pixel isolation portion 324 is formed of an oxide film. For example, the pixel isolation portion 324 is formed of a silicon oxide film (SiO 2 ). Further, the P-type fifth semiconductor region 315 formed around the pixel isolation portion 324 separates adjacent photoelectric conversion elements from each other by a potential barrier. The photoelectric conversion elements 102 are also separated by the potential of the fifth semiconductor region 315. The pixel isolation portion 324 may be a deep trench isolation (DTI) that penetrates the semiconductor layer 301, or a DTI that does not penetrate the semiconductor layer 301. The pixel isolation portion 324 may be configured to surround the entire periphery of the pixel of the photoelectric conversion element 102 in plan view, or for example, the pixel isolation portion 324 may be configured only at the opposite side portions of the pixel of the photoelectric conversion element 102.

[0069] The distance from the pixel isolation portion 324 to the pixel isolation portion 324 of an adjacent pixel or a pixel provided at the closest position can also be regarded as the size of one photoelectric conversion element 102. When the size of one photoelectric conversion element 102 is L, the distance d from the second surface to the avalanche multiplication region satisfies the relational expression of L√2 / 4 < d < L×√2. When the size and depth of the photoelectric conversion element 102 satisfy this relational expression, the electric field strength in the depth direction and the electric field strength in the plane direction in the vicinity of the first semiconductor region 311 become approximately the same. Since the variation in the time required for charge collection can be suppressed, the generation of timing jitter can be reduced.

[0070] On the second surface (light incident surface) side of the semiconductor layer 301, a pinning film 321, a planarization film 322, and a microlens 323 (a lens for light collection) are further formed. The microlens 323 is a transmissive resin, or a silicon oxide or silicon nitride. A filter layer (not shown) or the like may be further disposed on the second surface side of the semiconductor layer 301. Various optical filters (such as a color filter, an infrared cut filter, or a monochrome filter) can be used for the filter layer. For the color filter, an RGB color filter, an RGBW color filter, or the like can be used.

[0071] A wiring structure including a conductor and an insulating film is provided on the first surface of the semiconductor layer 301. The photoelectric conversion element 102 shown in FIG. 6 has an oxide film 341 and a protective film 342 from the side closer to the semiconductor layer 301, and further has a wiring layer made of a conductor laminated thereon. An interlayer film 343, which is an insulating film, is provided between the wiring and the semiconductor layer 301 and between the wiring layers. The protective film 342 is a film for protecting the avalanche diode from plasma damage and metal contamination during etching. For the protective film 342, SiN, which is a nitride film, is generally used, but SiON, SiC, SiCN, or the like may also be used.

[0072] The cathode wiring 331A is connected to the first semiconductor region 311. The anode wiring 331B supplies a voltage to the fifth semiconductor region 315 via the eighth semiconductor region 319, which is an anode contact. In the first embodiment, the cathode wiring 331A and the anode wiring 331B are formed in the same wiring layer. The wiring is made of a conductor containing a metal such as Cu or Al. In this cross section, the cathode wiring outer periphery is designated as 332A, and the anode wiring inner periphery facing 332A is designated as 332B. The dotted line 332C is a virtual line that divides the distance between the cathode wiring outer periphery 332A and the anode wiring inner periphery 332B at an equal distance.

[0073] In addition, in the photoelectric conversion element 102, a light-shielding film 326 and a reflecting member 328 are provided on the second surface side of the semiconductor layer 301 as viewed from the pixel separating section 324. The light-shielding film 326 blocks incident light. The reflecting member 328 reflects avalanche light. As shown in FIG. 6, at least a portion of each of the light-shielding film 326 and the reflecting member 328 overlaps with the pixel separating section 324 in a plan view. The reflecting member 328 is formed between the light-shielding film 326 and the pixel separating section 324. The reflecting member 328 contacts the light-shielding film 326 and also contacts the pixel separating section 324. In this manner, the light-shielding film 326, the reflecting member 328, and the pixel separating section 324 are arranged in a direction perpendicular to the second surface of the semiconductor layer 301 without any gaps. This prevents avalanche light generated in one pixel from being reflected by the light-shielding film 326. This makes it possible to prevent the avalanche light from penetrating into other pixels (causing crosstalk).

[0074] The light-shielding film 326 and the reflecting member 328 may be formed of the same material or different materials. The light-shielding film 326 and the reflecting member 328 may be formed of, for example, any metal (tungsten, titanium, tantalum, aluminum, gold, silver, copper, platinum, etc.). The light-shielding film 326 is formed of, for example, tungsten. For example, the reflecting member 328 is not limited to a metal, and may be formed of a material having a high reflectance at the avalanche emission wavelength. The reflecting member 328 is formed of, for example, aluminum or tungsten.

[0075] 7 shows a photoelectric conversion element 102' according to a comparative example of the first embodiment. The difference between the photoelectric conversion element 102' according to the comparative example and the photoelectric conversion element 102 according to the first embodiment is that the photoelectric conversion element 102' does not have a reflective member 328, but the photoelectric conversion element 102 does have a reflective member 328. Also, in the photoelectric conversion element 102', the pixel separation section 324 is formed of a metal, but in the photoelectric conversion element 102, the pixel separation section 324 is formed of an oxide film.

[0076] In the comparative example, if the reflecting member 328 is not present, the avalanche light will be reflected by the light-shielding film 326 as shown in optical path 701 in Fig. 7, and as a result, the avalanche light will reach an adjacent pixel. On the other hand, due to the presence of the reflecting member 328, the avalanche light is reflected by the reflecting member 328 as shown in optical path 601 in Fig. 6. Therefore, the avalanche light does not reach an adjacent pixel, and the avalanche light can escape to the outside of the photoelectric conversion element 102.

[0077] Furthermore, when the pixel separating section 324 is made of a metal as in the comparative example, it is possible to prevent avalanche light generated in one pixel from reaching other pixels. However, as shown in the optical path 702 in FIG. 7, the pixel separating section 324 absorbs incident light (it is unable to sufficiently reflect incident light). For this reason, when the pixel separating section 324 is made of a metal, the sensitivity of the photoelectric conversion element 102 may decrease. On the other hand, when the pixel separating section 324 is made of an oxide film, it is possible to reduce the amount of incident light absorbed by the pixel separating section 324 as shown in the optical path 602 in FIG. 6. For this reason, it is possible to suppress a decrease in the sensitivity of the photoelectric conversion element 102.

[0078] 8 shows the photoelectric conversion element 102 in a plan view of a cross section (AA' cross section) cut along line AA' in FIG. 6. The light-shielding film 326 and the reflecting member 328 surround the entire pixel (planarization film 322) in a plan view. The light-shielding film 326 and the reflecting member 328 are provided so as to enclose the first semiconductor region 311 in a plan view perpendicular to the second surface of the semiconductor layer 301. With this configuration, the avalanche light can be efficiently released to the outside of the photoelectric conversion element 102 by reflection of the avalanche light by the reflecting member 328. The light-shielding film 326 may not be disposed near the apex of the pixel in a plan view, but may be disposed only in other portions (opposite sides).

[0079] 9(A) to 9(C) are diagrams showing the relationship between "width Da of light-shielding film 326", "width Db of reflecting member 328", and "width Dc of the contact surface of pixel separating section 324 with reflecting member 328". Here, "width" refers to the length in a direction parallel to the second surface of semiconductor layer 301 and parallel to line AA' in FIG. 6. In the first embodiment, as shown in FIG. 9(A), "width Db of reflecting member 328" may be smaller than "width Da of light-shielding film 326". Alternatively, as shown in FIG. 9(B), "width Db of reflecting member 328" may be equal to "width Da of light-shielding film 326". On the other hand, as shown in FIG. 9(C), "width Db of reflecting member 328" may be smaller than "width Da of light-shielding film 326". If the "width Db of the reflective member 328" is larger than the "width Da of the light-shielding film 326", a large amount of incident light will be incident on the reflective member 328. For this reason, the reflective member 328 may absorb or reflect the incident light, and the amount of light incident on the pixel may decrease. In other words, the sensitivity of the photoelectric conversion element 102 may decrease. Therefore, in order to prevent a decrease in the sensitivity of the photoelectric conversion element 102, it is preferable that the "width Db of the reflective member 328" is equal to or smaller than the "width Da of the light-shielding film 326". Note that the width Dc may be larger than the width Db or the width Da, or may be smaller than the width Db or the width Da. For example, the width Da is 0.4 μm, the width Db is 0.2 μm, and the width Dc is 0.3 μm.

[0080] According to the first embodiment, the amount of incident light absorbed in the pixel separation section 324 can be reduced. Furthermore, the reflecting member 328 can reduce the amount of light (avalanche light) generated by avalanche multiplication in one pixel that is incident on other pixels. In other words, crosstalk due to avalanche light can be suppressed. Since the reflecting member 328 surrounds the entire circumference of one pixel in a plan view, for example, in the plane shown in FIG. 8, the amount of avalanche light that is incident on other pixels can be reduced. Furthermore, since the width of the reflecting member 328 is equal to or less than the width of the light-shielding film 326, the reflecting member 328 can prevent the absorption or reflection of the incident light. Therefore, appropriate light is incident on one pixel, and it is possible to maintain the photoelectric conversion element 102 at a high sensitivity.

[0081] Second embodiment In the first embodiment, there was no member between the microlens 323 and the light-shielding film 326 to sufficiently prevent the avalanche light from entering other pixels. Therefore, the avalanche light was reflected at the boundary surface between the microlens 323 and the planarization film 322, and the avalanche light was sometimes incident on other pixels. Therefore, in the second embodiment, the space between the microlens 323 and the pixel separation section 324 is filled with the light-shielding film 326 and the reflecting member 328, thereby sufficiently preventing the avalanche light from entering other pixels. Hereinafter, the surface of the planarization film 322 that contacts the microlens 323 is referred to as the "boundary surface 330."

[0082] 10 is a cross-sectional view of two pixels of a photoelectric conversion element 102 according to the second embodiment, viewed from a direction perpendicular to the surface direction of the substrate. In the second embodiment, unlike the first embodiment, the light-shielding film 326 is in contact with the boundary surface 330 (i.e., the microlens 323). In other words, the light-shielding film 326 and the reflecting member 328 penetrate the planarizing film 322 and the pinning film 321.

[0083] Therefore, even on a plane cut by a line BB', which is closer to the boundary surface 330 than the distance between the plane cut by the line AA' and the boundary surface 330, the reflecting member 328 surrounds the planarizing film 322 (pixel) as shown in FIG. 8.

[0084] 10, even if avalanche light hits an area close to the boundary surface 330, the reflecting member 328 can reflect the light, and the avalanche light travels along the optical path 901, for example. In other words, the avalanche light can escape to the outside of the photoelectric conversion element 102 without reaching an adjacent pixel. This makes it possible to suppress crosstalk, thereby improving the sensitivity of the photoelectric conversion element 102.

[0085] (Third embodiment) In the first and second embodiments, the pixel separating portion 324 is entirely formed of an oxide film. On the other hand, in the third embodiment, a part of the pixel separating portion 324 is formed of an oxide film, and the other part of the pixel separating portion 324 is formed of a metal.

[0086] 11 is a cross-sectional view of two pixels of the photoelectric conversion element 102 according to the third embodiment, as viewed in a direction perpendicular to the surface direction of the substrate. 1002. In FIG. 11, a first region 1001, a second region 1002, a reflecting member 328, and a light-shielding film 326 are laminated in this order. The distance between the first region 1001 and the avalanche multiplication region is shorter than the distance between the second region 1002 and the avalanche multiplication region. The first region 1001 is formed of a metal. The first region 1001 is formed of, for example, aluminum or tungsten, similar to the reflecting member 328. The first region 1001 may also be formed of copper. The second region 1002 is formed of an oxide film. Here, as shown in FIG. 11, the first region 1001 is disposed so as to be present between the avalanche multiplication regions (regions formed between the first semiconductor region 311 and the fourth semiconductor region 314) of two adjacent pixels.

[0087] Here, since the oxide film does not easily absorb incident light, the sensitivity of the photoelectric conversion element 102 can be improved. On the other hand, the metal film easily absorbs incident light, but can reduce the amount of avalanche light generated in one pixel that is incident on other pixels. Therefore, by arranging the first region 1001 made of metal near the avalanche multiplication region, crosstalk caused by avalanche light can be more efficiently suppressed. On the other hand, by arranging the second region 1002 made of an oxide film near the second surface of the semiconductor layer 301 that is likely to be hit by incident light, absorption of incident light by the pixel separation section 324 can be prevented.

[0088] According to the third embodiment, the pixel separator 324 has an area formed of metal. This can reduce the amount of avalanche light generated in one pixel that is incident on other pixels. This can improve the sensitivity of the photoelectric conversion element 102 (photoelectric conversion device 100).

[0089] (Fourth embodiment) The photoelectric conversion system according to this embodiment will be described with reference to Fig. 12. Fig. 12 is a block diagram showing a schematic configuration of the photoelectric conversion system according to this embodiment.

[0090] The photoelectric conversion devices described in the first to third 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. 12 illustrates a block diagram of a digital still camera as an example of these devices.

[0091] 12 includes an image pickup device 2504, which is an example of a photoelectric conversion device, and a lens 2502 that forms an optical image of a subject on the image pickup device 2504. The photoelectric conversion system also includes an aperture 2503 for varying the amount of light passing through the lens 2502, and a barrier 2501 for protecting the lens 2502. The lens 2502 and the aperture 2503 are an optical system that focuses light on the image pickup device 2504. The image pickup device 2504 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 2502 into an electrical signal.

[0092] The photoelectric conversion system also has a signal processing unit 2507 which is an image generating unit that generates an image by processing an output signal output from the imaging device 2504. The signal processing unit 2507 performs various corrections and compression as necessary to output image data. The signal processing unit 2507 may be formed on a semiconductor substrate on which the imaging device 2504 is provided, or may be formed on a semiconductor substrate separate from the imaging device 2504. Moreover, the imaging device 2504 and the signal processing unit 2507 may be formed on the same semiconductor substrate.

[0093] The photoelectric conversion system further includes a memory unit 2510 for temporarily storing image data, and an external interface unit (external I / F unit) 2513 for communicating with an external computer or the like. The photoelectric conversion system further includes a recording medium 2512 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) 2511 for recording or reading out data on the recording medium 2512. The recording medium 2512 may be built into the photoelectric conversion system, or may be removable.

[0094] The photoelectric conversion system further includes an overall control / calculation unit 2509 that performs various calculations and controls the entire digital still camera, and a timing generation unit 2508 that outputs various timing signals to the image pickup device 2504 and the signal processing unit 2507. 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 2504 and the signal processing unit 2507 that processes the output signal output from the image pickup device 2504.

[0095] The imaging device 2504 outputs an imaging signal to the signal processing unit 2507. The signal processing unit 2507 performs predetermined signal processing on the imaging signal output from the imaging device 2504, and outputs image data. The signal processing unit 2507 generates an image using the imaging signal.

[0096] 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.

[0097] Fifth embodiment The photoelectric conversion system and the moving object of this embodiment will be described with reference to Fig. 13(A) and Fig. 13(B). Fig. 13(A) is a diagram showing the configuration of the photoelectric conversion system of this embodiment, and Fig. 13(B) is a diagram showing the configuration of the moving object of this embodiment.

[0098] FIG. 13(A) shows an example of a photoelectric conversion system related to an in-vehicle camera. The photoelectric conversion system 2600 has an image capture device 2610. The image capture device 2610 is a photoelectric conversion device (image capture device) described in any of the above embodiments. The photoelectric conversion system 2600 has an image processing unit 2612 that performs image processing on a plurality of image data acquired by the image capture device 2610. The photoelectric conversion system 2600 also has a distance acquisition unit 2616 that calculates a distance to an object, and a collision determination unit 2618 that determines whether or not there is a possibility of collision based on the calculated distance. Here, the distance acquisition unit 2616 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 2618 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.

[0099] The photoelectric conversion system 2600 is connected to a vehicle information acquisition device 2620, and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The photoelectric conversion system 2600 is also connected to an ECU 2630, which is a control device that outputs a control signal to generate a braking force for the vehicle based on the determination result of the collision determination unit 2618. The photoelectric conversion system 2600 is also connected to an alarm device 2640 that issues an alarm to the driver based on the determination result of the collision determination unit 2618. For example, if the determination result of the collision determination unit 2618 indicates that there is a high possibility of a collision, the ECU 2630 applies the brakes, releases the accelerator, suppresses engine output, or performs other vehicle control to avoid a collision and reduce damage. The alarm device 2640 The system warns the user by sounding an alarm, displaying warning information on the screen of a car navigation system, or applying vibrations to the seat belt or steering wheel.

[0100] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are imaged by the photoelectric conversion system 2600. Fig. 13(B) shows a photoelectric conversion system for imaging the area in front of the vehicle (imaging range 2650). A vehicle information acquisition device 2620 sends an instruction to the photoelectric conversion system 2600 or the imaging device 2610. This configuration can further improve the accuracy of distance measurement.

[0101] 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 devices that widely use object recognition, such as an intelligent transport system (ITS).

[0102] Sixth embodiment The photoelectric conversion system of this embodiment will be described with reference to Fig. 14. Fig. 14 is a block diagram showing an example of the configuration of a range image sensor which is the photoelectric conversion system of this embodiment.

[0103] 14, the distance image sensor 2701 is configured to include an optical system 2707, a photoelectric conversion device 2708, an image processing circuit 2704, a monitor 2705, and a memory 2706. The distance image sensor 2701 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 2709 toward the subject and reflected from the surface of the subject.

[0104] The optical system 2707 is configured to have one or more lenses, and guides image light (incident light) from a subject to a photoelectric conversion device 2708 , forming an image on the light receiving surface (sensor portion) of the photoelectric conversion device 2708 .

[0105] As the photoelectric conversion device 2708 , 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 2708 is supplied to the image processing circuit 2704 .

[0106] The image processing circuit 2704 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric conversion device 2708. The distance image (image data) obtained by this image processing is then supplied to a monitor 2705 for display, or supplied to a memory 2706 for storage (recording).

[0107] In the range image sensor 2701 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.

[0108] Seventh embodiment The photoelectric conversion system of this embodiment will be described with reference to Fig. 15. Fig. 15 is a diagram showing an example of a schematic configuration of an endoscopic surgery system which is the photoelectric conversion system of this embodiment.

[0109] 15 shows a state in which an operator (doctor) 2831 is performing surgery on a patient 2832 on a patient bed 2833 using an endoscopic surgery system 2850. As shown in the figure, the endoscopic surgery system 2850 is composed of an endoscope 2800, a surgical tool 2810, and a cart 2834 on which various devices for endoscopic surgery are mounted.

[0110] The endoscope 2800 is composed of a lens barrel 2801, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 2832, and a camera head 2802 connected to the base end of the lens barrel 2801. In the illustrated example, the endoscope 2800 is configured as a so-called rigid lens barrel having a rigid lens barrel 2801, but the endoscope 2800 may be configured as a so-called flexible lens barrel having a flexible lens barrel.

[0111] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 2801. A light source device 2803 is connected to the endoscope 2800, and light generated by the light source device 2803 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 2801, and is irradiated via the objective lens toward an observation target in a body cavity of a patient 2832. The endoscope 2800 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0112] An optical system and a photoelectric conversion device are provided inside the camera head 2802, and reflected light (observation light) from an observation target is collected by the optical system onto the photoelectric conversion device. The observation light is photoelectrically converted by the photoelectric conversion device to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to an observation image. The photoelectric conversion device may be any of the photoelectric conversion devices (imaging devices) described in the above-described embodiments. The image signal is transmitted to a camera control unit (CCU) 2835 as RAW data.

[0113] The CCU 2835 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and performs overall control of the operations of the endoscope 2800 and the display device 2836. Furthermore, the CCU 2835 receives an image signal from the camera head 2802, 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.

[0114] Under the control of the CCU 2835 , the display device 2836 displays an image based on an image signal that has been subjected to image processing by the CCU 2835 .

[0115] The light source device 2803 is composed of a light source such as an LED (Light Emitting Diode), and supplies the endoscope 2800 with irradiation light when photographing an operation site or the like.

[0116] The input device 2837 is an input interface for the endoscopic surgery system 2850. A user can input various information and instructions to the endoscopic surgery system 2850 via the input device 2837.

[0117] The treatment tool control device 2838 controls the driving of the energy treatment tool 2812 for cauterizing tissue, incising, sealing blood vessels, or the like.

[0118] The light source device 2803 that supplies irradiation light to the endoscope 2800 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 a white light source is composed of a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so the light source device The white balance of the captured image can be adjusted in 2803. 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 object of observation 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 2802 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter to the image sensor.

[0119] Furthermore, the light source device 2803 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 2802 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.

[0120] The light source device 2803 may be configured to supply light in a predetermined wavelength band corresponding to the special light observation. In the 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 mucous membrane surface is photographed with high contrast by irradiating light in a narrower band than the irradiation light (i.e., white light) in normal observation. Alternatively, the special light observation may be a fluorescent observation in which an image is obtained by fluorescence generated by irradiating excitation light. In the fluorescent observation, it is possible to irradiate excitation light to the body tissue and observe the fluorescence from the body tissue, or to locally inject a reagent such as indocyanine green (ICG) into the body tissue and irradiate the body tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 2803 may be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0121] Eighth embodiment The photoelectric conversion system of this embodiment will be described with reference to Figs. 16(A) and 16(B). Fig. 16(A) describes glasses 2900 (smart glasses) which are the photoelectric conversion system of this embodiment. The glasses 2900 have a photoelectric conversion device 2902. The photoelectric conversion device 2902 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 2901. The photoelectric conversion device 2902 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 2902 is not limited to that shown in Fig. 16(A).

[0122] The glasses 2900 further include a control device 2903. The control device 2903 functions as a power source that supplies power to the photoelectric conversion device 2902 and the display device. The control device 2903 also controls the operations of the photoelectric conversion device 2902 and the display device. The lens 2901 is formed with an optical system for collecting light on the photoelectric conversion device 2902.

[0123] FIG. 16(B) illustrates glasses 2910 (smart glasses) according to one application example. The glasses 2910 have a control device 2912, and the control device 2912 is equipped with a photoelectric conversion device corresponding to the photoelectric conversion device 2902 and a display device. The lens 2911 is formed with an optical system for projecting light emitted from the photoelectric conversion device in the control device 2912 and the display device, and an image is projected onto the lens 2911. The control device 2912 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 to detect the line of sight. The infrared light emission 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 emission unit to the display unit in a planar view, deterioration of image quality is reduced.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] The display area may have a first display area and a second display area different from the first display area, and a high priority area may be determined from the first display area and the second display area based on line-of-sight information. The first 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.

[0129] 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.

[0130] When display control is performed based on visual recognition detection, the present invention is preferably applicable 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.

[0131] Ninth embodiment The above-described photoelectric conversion device and photoelectric conversion system may be applied to electronic devices such as so-called smartphones and tablets.

[0132] 17(A) and 17(B) are diagrams showing an example of an electronic device 3000 equipped with a photoelectric conversion device. Fig. 17(A) shows the front side of the electronic device 3000, and Fig. 17(B) shows the rear side of the electronic device 3000.

[0133] 17(A), a display 3010 for displaying an image is disposed in the center of the surface of the electronic device 3000. Then, along the upper side of the surface of the electronic device 3000, front cameras 3021 and 3022 using photoelectric conversion devices, an IR light source 3030 that emits infrared light, and a visible light source 3040 that emits visible light are disposed.

[0134] As shown in FIG. 17B, a photoelectric conversion The device is provided with rear cameras 3051 and 3052, an IR light source 3060 that emits infrared light, and a visible light source 3070 that emits visible light.

[0135] In the electronic device 3000 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.

[0136] (Tenth embodiment) 18 is a block diagram of an X-ray CT apparatus in this embodiment. The above-mentioned photoelectric conversion device and photoelectric conversion system are applicable to a detector of an X-ray CT apparatus. The X-ray CT apparatus 3100 in this embodiment includes an X-ray generation unit 3110, a wedge 3111, a collimator 3112, an X-ray detection unit 3120, and a top plate 3130. Furthermore, the X-ray CT apparatus 3100 includes a rotating frame 3140, a high-voltage generation device 3150, a data acquisition system (DAS) 3151, a signal processing unit 3152, a display unit 3153, and a control unit 3154.

[0137] The X-ray generating unit 3110 is composed of, for example, a vacuum tube that generates X-rays. A high voltage and a filament current are supplied to the vacuum tube of the X-ray generating unit 3110 from a high voltage generator 3150. X-rays are generated by irradiating thermal electrons from the cathode (filament) toward the anode (target).

[0138] The wedge 3111 is a filter that adjusts the amount of X-rays irradiated from the X-ray generating unit 3110. The wedge 3111 attenuates the amount of X-rays so that the X-rays irradiated from the X-ray generating unit 3110 to the subject have a predetermined distribution. The collimator 3112 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 3111. The X-rays generated by the X-ray generating unit 3110 are shaped into a cone beam via the collimator 3112 and irradiated to the subject on the tabletop 3130.

[0139] The X-ray detection unit 3120 is configured using the above-mentioned photoelectric conversion device or photoelectric conversion system. The X-ray detection unit 3120 detects X-rays that have passed through the subject from the X-ray generation unit 3110, and outputs a signal corresponding to the X-ray dose to the DAS 3151.

[0140] The rotating frame 3140 has an annular shape and is configured to be rotatable. An X-ray generation unit 3110 (wedge 3111, collimator 3112) and an X-ray detection unit 3120 are arranged facing each other inside the rotating frame 3140. The X-ray generation unit 3110 and the X-ray detection unit 3120 are rotatable together with the rotating frame 3140.

[0141] The high voltage generator 3150 includes a boost circuit, and outputs a high voltage to the X-ray generation unit 3110. The DAS 3151 includes an amplifier circuit and an A / D conversion circuit, and outputs a signal from the X-ray detection unit 3120 to the signal processing unit 3152 as digital data.

[0142] The signal processing unit 3152 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and is capable of executing image processing on digital data. The display unit 3153 includes a flat display device, and is capable of displaying X-ray images. The control unit 3154 includes a CPU, a ROM, a RAM, and the like, and controls the operation of the entire X-ray CT device 3100.

[0143] (Eleventh embodiment) A photoelectric conversion system according to an eleventh embodiment will be described with reference to Fig. 19. Fig. 19 is a block diagram showing a schematic configuration of an imaging system SYS, which is a photoelectric conversion system according to the eleventh embodiment. The imaging system SYS includes at least a photoelectric conversion device according to the above embodiment and a signal processing unit that processes a signal output from the photoelectric conversion device.

[0144] 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.

[0145] 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. The processing device PU processes signals obtained from the imaging device IS. The display device DU displays images obtained from the imaging device IS. The storage device MU stores images obtained from the imaging device IS.

[0146] (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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] The disclosure of this embodiment includes the following configuration. (Configuration 1) A photoelectric conversion device having a plurality of pixels, an avalanche multiplication region in which avalanche multiplication takes place; a pixel separator that separates pixels and has an oxide film formed thereon; a light-shielding film that at least partially overlaps the pixel isolation in a plan view and that blocks light; a reflective member that is formed between the pixel isolation and the light-shielding film so as to be in contact with the pixel isolation and the light-shielding film and that surrounds one pixel in a plan view; A photoelectric conversion device comprising: (Configuration 2) The width of the reflective member is equal to or smaller than the width of the light-shielding film. 2. The photoelectric conversion device according to configuration 1. (Configuration 3) The reflecting member is made of metal. 3. The photoelectric conversion device according to configuration 2. (Configuration 4) The reflecting member is made of aluminum or tungsten. 4. The photoelectric conversion device according to configuration 3. (Configuration 5) The light-shielding film is made of tungsten. 5. The photoelectric conversion device according to any one of configurations 1 to 4. (Configuration 6) The light-shielding film surrounds one pixel in a plan view. 6. The photoelectric conversion device according to any one of configurations 1 to 5. (Configuration 7) one or more films are laminated on the side where the light-shielding film is disposed as viewed from the pixel separation, The light-shielding film and the reflecting member penetrate the one or more films. 7. The photoelectric conversion device according to any one of configurations 1 to 6. (Configuration 8) Further comprising a microlens; The light-shielding film is in contact with the microlens. 8. The photoelectric conversion device according to any one of configurations 1 to 7. (Configuration 9) the pixel separation includes a first region and a second region; the first region, the second region, the reflective member, and the light-shielding film are laminated in this order, a distance between the first region and the avalanche multiplication region is shorter than a distance between the second region and the avalanche multiplication region; the first region is formed of a metal; the second region is formed of an oxide film; 9. The photoelectric conversion device according to any one of configurations 1 to 8. (Configuration 10) A photoelectric conversion device according to any one of configurations 1 to 9, a signal processing unit that generates an image using a signal output from the photoelectric conversion device; A photoelectric conversion system comprising: (Configuration 11) A moving object including the photoelectric conversion device according to any one of configurations 1 to 9, 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 12) An apparatus including the photoelectric conversion device according to any one of configurations 1 to 9, 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 and a mechanical device that operates based on information obtained by the photoelectric conversion device. [Explanation of symbols]

[0151] 100: photoelectric conversion device, 102: photoelectric conversion element, 324: pixel separator, 326: light shielding film, 328: reflecting member

Claims

1. A photoelectric conversion device having a plurality of pixels, an avalanche multiplication region in which avalanche multiplication takes place; a pixel separator that separates pixels and has an oxide film formed thereon; a light-shielding film that at least partially overlaps the pixel isolation in a plan view and that blocks light; a reflective member that is formed between the pixel isolation and the light-shielding film so as to be in contact with the pixel isolation and the light-shielding film and that surrounds one pixel in a plan view; A photoelectric conversion device comprising:

2. The width of the reflective member is equal to or smaller than the width of the light-shielding film.

2. The photoelectric conversion device according to claim 1.

3. The reflecting member is made of metal.

3. The photoelectric conversion device according to claim 2.

4. The reflecting member is made of aluminum or tungsten.

4. The photoelectric conversion device according to claim 3.

5. The light-shielding film is made of tungsten.

2. The photoelectric conversion device according to claim 1.

6. the light-shielding film surrounds one pixel in a plan view; 2. The photoelectric conversion device according to claim 1.

7. one or more films are laminated on the side on which the light-shielding film is disposed as viewed from the pixel separation, The light-shielding film and the reflecting member penetrate the one or more films.

2. The photoelectric conversion device according to claim 1.

8. Further comprising a microlens; The light-shielding film is in contact with the microlens.

2. The photoelectric conversion device according to claim 1.

9. the pixel separation includes a first region and a second region; the first region, the second region, the reflective member, and the light-shielding film are laminated in this order, a distance between the first region and the avalanche multiplication region is shorter than a distance between the second region and the avalanche multiplication region; the first region is formed of a metal; the second region is formed of an oxide film; 2. The photoelectric conversion device according to claim 1.

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

11. A moving object including the photoelectric conversion device according to any one of claims 1 to 9, A control unit that controls the movement of the moving body using a signal output from the photoelectric conversion device. A moving object characterized by:

12. An apparatus comprising the photoelectric conversion device according to any one of claims 1 to 9, 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 and a mechanical device that operates based on information obtained by the photoelectric conversion device.

Images