Photoelectric conversion device, photoelectric conversion system, and movable object

Abstract

The present application relates to a photoelectric conversion device, a photoelectric conversion system, and a movable object. The photoelectric conversion device includes a first avalanche diode including a first semiconductor region of a first conductivity type in which a majority carrier is a charge carrier of the same conductivity type as a signal charge; a second avalanche diode including a second semiconductor region of the first conductivity type and arranged adjacent to the first avalanche diode; and a third avalanche diode including an eighth semiconductor region of the first conductivity type and arranged adjacent to the second avalanche diode.

Description

[0001] This application is a divisional application of the invention patent application filed on January 20, 2021, with application number 202180011802.0 (international application number PCT / JP2021 / 001744) and entitled "Photoelectric Conversion Device, Photoelectric Conversion System and Movable Object". Technical Field

[0002] This invention relates to photoelectric conversion devices, photoelectric conversion systems, and movable objects. Background Technology

[0003] A photoelectric conversion device is known that digitally counts the number of photons arriving at a light receiving section and outputs the count value as a digital signal from a pixel. Patent Document 1 discloses a photodetector using an avalanche diode, which induces avalanche multiplication in the PN junction region constituting the semiconductor region of the photoelectric conversion section. In the photodetector of Patent Document 1, a high-density P-type semiconductor region for forming electrical contacts is arranged between the N-type semiconductor regions of adjacent avalanche diodes.

[0004] Reference List Patent documents Patent Document 1: Japanese Patent Application Publication No. 2018-201005 Summary of the Invention

[0005] Technical issues According to Patent Document 1, when the pixel size decreases, the distance between the P-type semiconductor region and the N-type semiconductor region constituting the avalanche diode decreases. When a potential is supplied to the avalanche diode in this state, a local high electric field region is formed by the N-type semiconductor region and the high-density P-type semiconductor region used to form electrical contacts, and dark current is likely to be generated.

[0006] Technical solutions to the problem According to one aspect of the present invention, a photoelectric conversion device includes: a first avalanche diode comprising a first semiconductor region of a first conductivity type in which the majority carriers are charge carriers of the same conductivity type as the signal charge; and a second avalanche diode comprising a second semiconductor region of the first conductivity type and arranged adjacent to the first avalanche diode, wherein a first isolation portion is disposed between the first semiconductor region and the second semiconductor region, the first isolation portion being composed of a third semiconductor region of the first conductivity type, or a fourth semiconductor region of the second conductivity type and the third semiconductor region, and wherein in the third semiconductor region, the impurity concentration Nd of the third semiconductor region, the impurity concentration Na of the fourth semiconductor region, the elementary charge q, and the dielectric constant of the semiconductor are... The potential difference V between the PN junctions of the third semiconductor region and the fourth semiconductor region, and the length D of the fourth semiconductor region sandwiched by the third semiconductor region, satisfy the following expression.

[0007] [Expression 1] According to one aspect of the present invention, a photoelectric conversion device includes: a substrate having a first surface and a second surface opposite to the first surface; a first avalanche diode including a first semiconductor region of a first conductivity type disposed at a first depth in the substrate, wherein the majority carriers are charge carriers of the same conductivity type as the signal charge, and a fifth semiconductor region of a second conductivity type disposed at a second depth between the first depth and the second surface, wherein the second conductivity type is different from the first conductivity type; and a second avalanche diode including a second semiconductor region of the first conductivity type disposed at the first depth in the substrate and a sixth semiconductor region of the second conductivity type disposed at the second depth, the second avalanche diode being arranged adjacent to the first avalanche diode, wherein a first isolation portion is disposed between the first semiconductor region and the second surface. At least one of the intrinsic semiconductor region, the third semiconductor region of the first conductivity type, and the fourth semiconductor region of the second conductivity type is disposed in the first isolation portion at the first depth between the semiconductor regions. A seventh semiconductor region of the second conductivity type is disposed at the second depth between the fifth semiconductor region and the sixth semiconductor region. On the line passing through the first isolation portion and the seventh semiconductor region, the potential height relative to the signal charge decreases from the seventh semiconductor region toward the first isolation portion. The difference between the potential height relative to the signal charge in the first semiconductor region and the potential height relative to the signal charge in the fifth semiconductor region is greater than the difference between the potential height relative to the signal charge in the first isolation portion and the potential height relative to the signal charge in the seventh semiconductor region.

[0008] According to one aspect of the present invention, a photoelectric conversion device includes: a first avalanche diode comprising a first semiconductor region of a first conductivity type in which the majority carriers are charge carriers of the same conductivity type as the signal charge; and a second avalanche diode comprising a second semiconductor region of the first conductivity type and arranged adjacent to the first avalanche diode, and the photoelectric conversion device includes: a first counter circuit configured to count avalanche currents generated by avalanche multiplication in the first avalanche diode; and a second counter circuit, different from the first counter circuit and configured to count avalanche currents generated by avalanche multiplication in the second avalanche diode, and in a top view, a contact plug for applying a bias voltage to a node of the first avalanche diode is not arranged between the first semiconductor region and the second semiconductor region.

[0009] Advantages of the present invention According to the present invention, in a photoelectric conversion device using an avalanche diode, the pixel size can be reduced while suppressing the increase of dark current. Attached Figure Description

[0010] [ Figure 1 ] Figure 1 This is a block diagram of a photoelectric conversion device.

[0011] [ Figure 2 ] Figure 2 It is a pixel-based diagram.

[0012] [ Figure 3 ] Figure 3 This is a partially enlarged top view of the photoelectric conversion device of the first embodiment.

[0013] [ Figure 4A ] Figure 4A This is a cross-sectional view of the photoelectric conversion device of the first embodiment.

[0014] [ Figure 4B ] Figure 4B This is a cross-sectional view of the photoelectric conversion device of the first embodiment.

[0015] [ Figure 5A ] Figure 5A This is a potential diagram of the photoelectric conversion device in the first embodiment.

[0016] [ Figure 5B ] Figure 5B This is a potential diagram of the photoelectric conversion device in the first embodiment.

[0017] [ Figure 5C ] Figure 5C This is a potential diagram of the photoelectric conversion device in the first embodiment.

[0018] [ Figure 6A ] Figure 6A This is a cross-sectional view of the photoelectric conversion device of the comparative example.

[0019] [ Figure 6B ] Figure 6B This is a potential diagram of a comparative photoelectric conversion device.

[0020] [ Figure 7 ] Figure 7 This is a partially enlarged top view of the photoelectric conversion device of the second embodiment.

[0021] [ Figure 8 ] Figure 8 This is a cross-sectional view of the photoelectric conversion device of the second embodiment.

[0022] [ Figure 9 ] Figure 9 This is a partially enlarged top view of the photoelectric conversion device of the third embodiment.

[0023] [ Figure 10 ] Figure 10 This is a cross-sectional view of the photoelectric conversion device of the third embodiment.

[0024] [ Figure 11 ] Figure 11 This is a variant of the third embodiment.

[0025] [ Figure 12 ] Figure 12 This is a partially enlarged top view of the photoelectric conversion device of the fourth embodiment.

[0026] [ Figure 13 ] Figure 13 This is a cross-sectional view of the photoelectric conversion device of the fourth embodiment.

[0027] [ Figure 14 ] Figure 14 This is a cross-sectional view of the photoelectric conversion device of the fifth embodiment.

[0028] [ Figure 15 ] Figure 15 This is a partially enlarged top view of the photoelectric conversion device of the sixth embodiment.

[0029] [ Figure 16 ] Figure 16 This is a cross-sectional view of the photoelectric conversion device of the sixth embodiment.

[0030] [ Figure 17 ] Figure 17 This is a partially enlarged top view of the photoelectric conversion device of the seventh embodiment.

[0031] [ Figure 18 ] Figure 18 This is a cross-sectional view of the photoelectric conversion device of the seventh embodiment.

[0032] [ Figure 19 ] Figure 19 This is a cross-sectional view of the photoelectric conversion device of the eighth embodiment.

[0033] [ Figure 20 ] Figure 20 This is a cross-sectional view of the photoelectric conversion device of the ninth embodiment.

[0034] [ Figure 21 ] Figure 21 It is a photoelectric conversion system according to the tenth embodiment.

[0035] [ Figure 22 ] Figure 22 It is a photoelectric conversion system according to the eleventh embodiment.

[0036] [ Figure 23A ] Figure 23A This is a schematic diagram of the photoelectric conversion system and the movable object of the twelfth embodiment.

[0037] [ Figure 23B ] Figure 23B This is a schematic diagram of the photoelectric conversion system and the movable object of the twelfth embodiment.

[0038] [ Figure 24 ] Figure 24 This is a flowchart illustrating the operation of the photoelectric conversion system of the twelfth embodiment.

[0039] [ Figure 25 ] Figure 25 It is a photoelectric conversion system according to the thirteenth embodiment.

[0040] [ Figure 26 ] Figure 26 It is a photoelectric conversion system according to the fourteenth embodiment.

[0041] [ Figure 27 ] Figure 27 This is a block diagram of a photoelectric conversion system according to the fourteenth embodiment.

[0042] [ Figure 28A ] Figure 28A It is a photoelectric conversion system according to the fifteenth embodiment.

[0043] [ Figure 28B ] Figure 28B It is a photoelectric conversion system according to the fifteenth embodiment.

[0044] [ Figure 28C ] Figure 28C It is a photoelectric conversion system according to the fifteenth embodiment.

[0045] [ Figure 29 ] Figure 29 It is a photoelectric conversion system according to the fifteenth embodiment.

[0046] [ Figure 30A ] Figure 30A This is an experimental example of a photoelectric conversion system according to the fifteenth embodiment.

[0047] [ Figure 30B ] Figure 30B This is an experimental example of a photoelectric conversion system according to the fifteenth embodiment.

[0048] [ Figure 30C ] Figure 30C This is an experimental example of a photoelectric conversion system according to the fifteenth embodiment.

[0049] [ Figure 31A ] Figure 31A It is a photoelectric conversion device according to the sixteenth embodiment.

[0050] [ Figure 31B ] Figure 31B It is a photoelectric conversion device according to the sixteenth embodiment.

[0051] [ Figure 32 ] Figure 32 It is the spectral transmittance of the filter according to the seventeenth embodiment.

[0052] [ Figure 33A ] Figure 33A This is an example of the arrangement of pixels and filters according to the seventeenth embodiment.

[0053] [ Figure 33B ] Figure 33B This is an example of the arrangement of pixels and filters according to the seventeenth embodiment.

[0054] [ Figure 34 ] Figure 34 This is an example of the arrangement of pixels and filters according to the seventeenth embodiment.

[0055] [ Figure 35A ] Figure 35A This is an example of the arrangement of pixels and filters according to the seventeenth embodiment.

[0056] [ Figure 35B ] Figure 35B This is an example of the arrangement of pixels and filters according to the seventeenth embodiment. Detailed Implementation

[0057] The embodiments illustrated below are used to demonstrate the technical concept of the present invention and are not intended to limit the invention. For ease of description, the dimensions and positional relationships of the components shown in the figures may be exaggerated. In the following description, the same numbers are assigned to the same structures, and their descriptions may be omitted.

[0058] The embodiments illustrated below particularly relate to photoelectric conversion devices including a SPAD (single-photon avalanche diode) that counts the number of photons incident on the avalanche diode. The photoelectric conversion device includes at least an avalanche diode.

[0059] In the following description, the anode of the avalanche diode has a fixed potential, and the signal is obtained from the cathode side. Therefore, the semiconductor region of the first conductivity type refers to an N-type semiconductor region, and the semiconductor region of the second conductivity type refers to a P-type semiconductor region. In the semiconductor region of the first conductivity type, the majority carriers are charge carriers of the same conductivity type as the signal charge. Note that the invention also applies even when the cathode of the avalanche diode has a fixed potential and the signal is obtained from the anode side. In this case, the semiconductor region of the first conductivity type refers to a P-type semiconductor region, and the semiconductor region of the second conductivity type refers to an N-type semiconductor region. In the semiconductor region of the first conductivity type, the majority carriers are charge carriers of the same conductivity type as the signal charge. The following describes the case where a fixed potential is set at one node of the avalanche diode, but the potentials at both nodes may fluctuate.

[0060] Figure 1 This is a block diagram of the photoelectric conversion device 1000 of this embodiment. The photoelectric conversion device 1000 includes a pixel area 111, a horizontal scanning circuit section 105, a signal line 104, and a vertical scanning circuit section 103.

[0061] Multiple pixels 110 are arranged in two dimensions in pixel region 111. Each pixel 110 consists of a photoelectric conversion unit 101 and a pixel signal processing unit 102. The photoelectric conversion unit 101 converts light into an electrical signal. The pixel signal processing unit 102 outputs the converted electrical signal to signal line 104.

[0062] The vertical scanning circuit section 103 and the horizontal scanning circuit section 105 provide control pulses to each pixel 110. Logic circuitry such as a shift register or an address decoder is used as the vertical scanning circuit section 103.

[0063] Each signal line 104 provides the digital signal output from the pixel 110 selected by the vertical scanning circuit section 103 as a potential signal to the subsequent circuit of the pixel 110.

[0064] exist Figure 1 In the pixel region 111, the array of pixels 110 can be arranged in one dimension. Alternatively, the pixel region 111 can be divided into blocks, each having multiple pixel columns, and a vertical scanning circuit section 103 and a horizontal scanning circuit section 105 can be arranged for each block. Furthermore, the vertical scanning circuit section 103 and the horizontal scanning circuit section 105 can be arranged for each pixel column.

[0065] It is not necessary to set the function of the pixel signal processing unit 102 for each pixel 110. For example, multiple pixels 110 can share a single pixel signal processing unit 102, and signal processing can be performed sequentially. Furthermore, to increase the aperture ratio of the photoelectric conversion unit 101, at least a portion of the pixel signal processing unit 102 can be disposed on a different semiconductor substrate (second substrate) than the photoelectric conversion unit 101. In this case, the photoelectric conversion unit 101 and the pixel signal processing unit 102 are electrically connected to each other via connection lines provided for each pixel. The avalanche diode of the photoelectric conversion unit 101 is preferably disposed on the first substrate, and other structures are preferably disposed on the second substrate. The vertical scan circuit unit 103, the horizontal scan circuit unit 105, and the signal line 104 can be disposed on the second substrate.

[0066] Figure 2 This is a block diagram of pixel 110 including equivalent circuitry according to this embodiment. Figure 2 In this configuration, a single pixel 110 is composed of a photoelectric conversion unit 101 and a pixel signal processing unit 102.

[0067] The photoelectric conversion unit 101 has one or more avalanche diodes 201, quenching elements 202 and waveform shaping units 203 arranged in a row.

[0068] Avalanche diode 201 generates charge pairs based on incident light through photoelectric conversion. A potential VH, which is higher than the potential VL supplied to the anode, is provided to the cathode of avalanche diode 201. Then, a potential with this reverse bias is provided to the anode and cathode of avalanche diode 201, causing photons incident on avalanche diode 201 to undergo avalanche multiplication. When photoelectric conversion occurs under the state of providing a reverse bias potential, the charge generated by the incident light causes avalanche multiplication to generate an avalanche current.

[0069] When a reverse bias voltage is applied, the avalanche diode enters Geiger mode operation when the potential difference between the anode and cathode exceeds the breakdown voltage. An avalanche diode that uses Geiger mode operation for rapid detection of weak signals at the single-photon level is a SPAD (single-photon avalanche diode).

[0070] Quenching element 202 is connected to a power supply providing a high potential VH and avalanche diode 201. Quenching element 202 is constructed from a P-type MOS transistor or a resistive element such as a polysilicon resistor. Alternatively, quenching element 202 can be constructed from multiple MOS transistors connected in series. When the photocurrent is multiplied by avalanche multiplication in avalanche diode 201, the current obtained through the multiplied charge flows to the connection node between avalanche diode 201 and quenching element 202. Due to the voltage drop caused by this current, the potential at the cathode of avalanche diode 201 decreases, and avalanche diode 201 no longer forms electron avalanches. In this way, avalanche multiplication in avalanche diode 201 stops. Afterwards, since the potential VH of the power supply is provided to the cathode of avalanche diode 201 via quenching element 202, the potential provided to the cathode of avalanche diode 201 returns to potential VH. That is, the operating region of avalanche diode 201 re-enters Geiger mode operation. In this way, the quenching element 202 acts as a load circuit (quenching circuit) during charge multiplication via avalanche multiplication and suppresses avalanche multiplication (quenching operation). Furthermore, the quenching element causes the operating region of the avalanche diode to re-enter Geiger mode after avalanche multiplication is suppressed.

[0071] The waveform shaping unit 203 is connected to the connection node between the node of the avalanche diode 201 and the node of the quenching element 202. A rectangular pulse signal is output by shaping the potential change at the cathode of the avalanche diode 201 obtained during photon detection. For example, an inverter circuit can be used as the waveform shaping unit 203. An example using a single inverter as the waveform shaping unit 203 is shown, but a circuit obtained by connecting multiple inverters in series can also be used. Not only inverters can be used, but other circuits with waveform shaping effects can also be used.

[0072] The pixel signal processing unit 102 includes a counter circuit 204 and a selection circuit 205.

[0073] The counter circuit 204 is connected to the waveform shaping unit 203. The pulse signal output from the waveform shaping unit 203 is counted by the counter circuit 204. In the case where the counter circuit 204 is, for example, an N-bit counter (N: a positive integer), the pulse signal of a single photon can be counted up to approximately 2^N. The count signal is held as a detection signal. Furthermore, when a control pulse Res is provided via the control line, the signal held in the counter circuit 204 is reset.

[0074] The selector circuit 205 is connected to the counter circuit 204 and the signal line 104. It is connected via the control line from... Figure 1The vertical scanning circuit section 103 provides a control pulse Sel to the selection circuit 205 and switches whether to output the count value of the counter circuit 204 to the signal line 104. The selection circuit 205 includes, for example, a buffer circuit configured to output a signal.

[0075] Note that a switch, such as a transistor, can be arranged between the quenching element 202 and the avalanche diode 201 to switch between a mode in which the avalanche diode 201 can perform avalanche multiplication and a mode in which the avalanche diode 201 cannot perform avalanche multiplication. Similarly, a switch, such as a transistor, can be used to electrically switch the supply of a high potential VH or a low potential VL to the avalanche diode 201. Additionally, a switch, such as a transistor, can be arranged between the photoelectric conversion unit 101 and the pixel signal processing unit 102 to control the signal input from the photoelectric conversion unit 101 to the counter circuit 204.

[0076] In a pixel region 111 where multiple pixels 110 are arranged in a matrix shape, an image can be captured by a rolling shutter operation. During the rolling shutter operation, the counter circuit 204 is reset sequentially for each row, and the signal held in the counter circuit 204 is output sequentially for each row.

[0077] Alternatively, an image can be captured via global electronic shutter operation. During global electronic shutter operation, the counter circuit 204 is simultaneously reset to count all pixel rows, and signals held in the counter circuit 204 are sequentially output for each row. Note that when performing global electronic shutter operation, it is preferable to provide a component for switching between counting by the counter circuit 204 and not counting. The switching component is, for example, the switch described above.

[0078] Figure 2 The construction using counter circuit 204 is shown. Instead of counter circuit 204, a construction can be used to obtain pulse detection timing using time-to-digital converter circuit (time-to-digital converter: hereinafter referred to as TDC) or memory.

[0079] At this time, the generation timing of the pulse signal output from the waveform shaping unit 203 is converted into a digital signal by the TDC. To measure the timing of the pulse signal, the control pulse Ref (reference signal) is transmitted from... Figure 1 The vertical scanning circuit section 103 is provided to the TDC. By using the control pulse pREF as a reference, the TDC obtains the signal when the input timing of the signal output from each pixel via the waveform shaping section 203 is set to a relative time, and sends it as a digital signal.

[0080] <First Embodiment> Will use Figures 3 to 5CThe structure of the photoelectric conversion device according to the first embodiment is described.

[0081] Figure 3 This is a partially enlarged top view of the pixel region of the photoelectric conversion device according to the first embodiment. Figure 4A It is along Figure 3 A schematic cross-sectional view taken from line A-A'. Figure 4B It is along Figure 3 The schematic cross-sectional view of the section cut off from B-B' in the diagram. Figure 5A It is along Figure 4A Potential diagrams of X-X' and Y-Y' in the figure. Figure 5B It is along Figure 4A Potential diagram of V-V' in the middle. Figure 5C It is along Figure 4B Potential diagram of W-W' in the middle.

[0082] Figure 3 Four pixels are shown, including two pixels in a first direction in the top view and two pixels in a second direction orthogonal to the first direction. It can be mentioned that the first direction refers to the direction along the pixel row (row direction). That is, the first direction is the direction corresponding to the view from one pixel to another when there are multiple pixels in the first row. Furthermore, it can be mentioned that the second direction refers to the direction along the pixel column (column direction). The direction intersecting the first and second directions is the third direction. Hereinafter, for ease of description, Figure 3 In this embodiment, the avalanche diode in the first row and first column is referred to as the first avalanche diode, the avalanche diode in the first row and second column is referred to as the second avalanche diode, and the avalanche diode in the second row and second column is referred to as the third avalanche diode. According to this embodiment, a pixel is composed of a counter and a sensitivity region for generating a signal to be read from a single counter. In this specification, a "top view" refers to a view in a direction perpendicular to a plane parallel to the light incident surface of the substrate.

[0083] like Figure 4A and Figure 4B As shown, an avalanche diode is formed inside a substrate 40. The substrate 40 has a first surface 40A and a second surface 40B opposite to the first surface 40A. The first surface 40A is the surface on which contact plugs 6 and 7 are formed. Furthermore, the gate electrode of the transistor can be disposed on the first surface 40A side. The description will be provided assuming light is incident from the second surface 40B side of the substrate 40, but light can be incident from the first surface 40A side of the substrate 40. In this specification, "depth" refers to the depth from the first surface 40A toward the second surface 40B.

[0084] Each avalanche diode has at least a semiconductor region of a first conductivity type (N-type semiconductor region 1) formed at a first depth and a semiconductor region of a second conductivity type (P-type semiconductor region 5) formed at a second depth, the second depth being deeper than the first depth from the first surface. The N-type semiconductor region 1 and the P-type semiconductor region 5 (seventh semiconductor region) form a PN junction. The P-type semiconductor region 5 is, for example, a well region.

[0085] A contact plug 6, which provides a potential VH via a quenching element 202, is connected to the N-type semiconductor region 1. A contact plug 7, which provides a potential VL, is connected to the P-type semiconductor region 4. A potential VL is provided to the P-type semiconductor region 5 via the contact plug 7 and the P-type semiconductor region 4.

[0086] In a cross-section passing through multiple N-type semiconductor regions 1, a first isolation portion 20 is disposed between N-type semiconductor regions 1. Additionally, in a cross-section different from the aforementioned specific cross-section, a second isolation portion 30 is disposed between N-type semiconductor regions 1. For example, in... Figure 3 and Figures 4A-4B In the cross-section passing through the N-type semiconductor region 1 of the first avalanche diode and the N-type semiconductor region 1 of the second avalanche diode, a first isolation portion 20 is arranged between the respective N-type semiconductor regions 1. In the cross-section passing through the N-type semiconductor regions 1 of the second avalanche diode and the N-type semiconductor region 1 of the third avalanche diode, the first isolation portion 20 is arranged between the respective N-type semiconductor regions 1. In the cross-section passing through the N-type semiconductor regions 1 of the first avalanche diode and the N-type semiconductor region 1 of the third avalanche diode, a second isolation portion 30 is arranged between the respective N-type semiconductor regions 1. The second isolation portion 30 includes at least a P-type semiconductor region 4.

[0087] like Figure 5A As shown, the difference between the potential height relative to electrons in N-type semiconductor region 3 and the potential height relative to electrons in P-type semiconductor region 5 is smaller than the difference between the potential height relative to electrons in N-type semiconductor region 1 and the potential height relative to electrons in P-type semiconductor region 5. The difference along X-X' between the potential height relative to electrons in N-type semiconductor region 1 and the potential height relative to electrons in P-type semiconductor region 5 is configured to enable avalanche multiplication. The difference along Y-Y' between the potential height relative to electrons in the first isolation portion 20 and the potential height relative to electrons in P-type semiconductor region 5 is configured not to cause avalanche multiplication. The maximum potential height relative to electrons along Y-Y' is lower than the maximum potential height relative to electrons along X-X'.

[0088] Figure 5B and Figure 5CThe potential distributions relative to the signal charge along V-V' and along W-W' are shown. According to this embodiment, in the state of stabilizing the avalanche diode's potential to await photons (static), the potential height of the N-type semiconductor region 1 relative to the signal charge is at its lowest. Then, when a state is established where photons or dark charges are detected and avalanche multiplication is induced in the avalanche diode (quenching), the potential height of the N-type semiconductor region 1 relative to the signal charge gradually increases. The height of the potential barrier in the first isolation portion 20 is preferably higher than the potential height of the N-type semiconductor region 1 relative to the signal charge when avalanche multiplication is induced. This is because, in this way, charge crosstalk between adjacent avalanche diodes can be reduced, and it helps to function as an isolation portion. Note that if it is not necessary to increase the resolution of the photoelectric conversion device, a potential barrier may not be formed in the first isolation portion 20. That is, in the state where avalanche multiplication is to be induced, the potential height of the first isolation portion 20 can be substantially the same as the potential height of the N-type semiconductor region 1.

[0089] According to this embodiment, the potential barrier formed by the first isolation portion 20 is lower than the potential barrier formed by the second isolation portion 30. Similarly, in this case, reducing the pixel size helps to reduce crosstalk. The light detection device described in Patent Document 1 will be compared with... Figures 6A-6B The comparative examples shown are compared while the reasons are described.

[0090] exist Figure 6A In the comparative example shown, N-type semiconductor region 3 is arranged between N-type semiconductor region 1 and N-type semiconductor region 8. Furthermore, N-type semiconductor region 3 is arranged to sandwich P-type semiconductor region 8.

[0091] In the photodetector described in Patent Document 1, a P-type semiconductor region with a high impurity concentration is arranged to surround the entire circumference of the N-type semiconductor region constituting the avalanche diode in a top view. In this case, the semiconductor regions need to be arranged at a predetermined distance to ensure the breakdown voltage between the N-type semiconductor region and the P-type semiconductor region. Therefore, the N-type semiconductor regions of each avalanche diode cannot be close to each other, and the pixel pitch cannot be reduced.

[0092] Furthermore, in the photoelectric conversion device shown in the comparative example, the impurity concentration in the P-type semiconductor region 8 is low, but the P-type semiconductor region is still a neutral region. Therefore, as... Figure 6B As shown, along Y-Y', the potential relative to the signal charge increases as it approaches Y. In this structure, electrons generated in the region between P-type semiconductor region 8 and P-type semiconductor region 11 are also read as signal charges. That is, in the semiconductor region 13 between P-type semiconductor region 8 and P-type semiconductor region 11, it is not possible to separate the sensitivity region for each N-type semiconductor region 1.

[0093] Note that, when used only in this specification, the term "impurity concentration" refers to the net impurity concentration compensated by the impurity of the reverse-conducting impurity. That is, "impurity concentration" refers to the NET concentration. Regions with a higher P-type added impurity concentration than N-type added impurity concentration are P-type semiconductor regions. Conversely, regions with a higher N-type added impurity concentration than P-type added impurity concentration are N-type semiconductor regions.

[0094] According to this embodiment, the semiconductor regions where the area between N-type semiconductor regions 1 is depleted are arranged as a first isolation portion 20 between a plurality of N-type semiconductor regions 1. Since the first isolation portion 20 is depleted, therefore... Figure 5A As shown, the potential distribution along Y-Y' decreases from the P-type semiconductor region 5 toward the first isolation portion 20. In other words, the potential distribution along Y-Y' monotonically decreases from the P-type semiconductor region toward the first isolation portion 20. Therefore, a state is established where charge also flows toward the first isolation portion 20. The charge that has already flowed toward the first isolation portion 20 flows through the N-type semiconductor region 1, but since the potential difference between the N-type semiconductor region 1 and the first isolation portion 20 is not a potential difference of the magnitude that would cause avalanche multiplication, an avalanche current is not generated and is not counted by the counter circuit. Therefore, the potential difference is not read as a signal. That is to say, not only the first isolation portion 20, but also the region between the first isolation portion 20 and the second surface is essentially used as a dead zone and can be used as an isolation portion. Therefore, even when the pixel pitch decreases, signals can be read for each pixel while reducing crosstalk.

[0095] According to this embodiment, the N-type semiconductor region 3, with an impurity concentration lower than that of the N-type semiconductor region 1, is arranged as the first isolation portion 20. In other words, a configuration is adopted in which, instead of passing through the entire circumference of the N-type semiconductor region 1 via the P-type semiconductor region 4 in a top view, the P-type semiconductor region 4 is arranged in a portion of the periphery of the N-type semiconductor region 1, and the P-type semiconductor region 4 is not arranged in other portions. That is, a configuration is adopted in which it is necessary to ensure that the voltage-resistant P-type semiconductor region 4 is only partially arranged, while in other portions, the height of the potential barrier is set to a level that prevents signal charge leakage. Not limited thereto, as long as the first isolation portion 20 is exhausted, the P-type semiconductor region 4 and the N-type semiconductor region 3 arranged to sandwich the P-type semiconductor region 4 can be arranged as the first isolation portion 20, as in the embodiment described below. Furthermore, intrinsic semiconductor regions (i-type semiconductor regions) can be arranged in at least a portion thereof. Additionally, only the P-type semiconductor region 4 can be arranged between the N-type semiconductor regions 1.

[0096] The length of the first isolation portion 20 in the first direction is shorter than the length of the second isolation portion 30 in the third direction. In other words, the distance between the N-type semiconductor regions 1 in the first direction is shorter than the distance between the N-type semiconductor regions 1 in the third direction. For example, the ratio of the length of the first isolation portion 20 to the length of the second isolation portion 30 is less than 1 and equal to or greater than 1 / 8. For example, the distance between the avalanche multiplication portions in the first direction is preferably 1 μm or greater. To ensure withstand voltage, the distance between the avalanche multiplication portions in the first direction can be set to 0.5 μm or greater, and preferably 1 μm or greater. On the other hand, to reduce the area of ​​the pixel region, the distance between the avalanche multiplication portions in the first direction can be set to 10 μm or less, and preferably 4 μm or less.

[0097] The impurity concentration of the N-type semiconductor region 3 is preferably lower than that of the P-type semiconductor region 5 disposed at a position overlapping the N-type semiconductor region 3 in the top view. In this way, the N-type semiconductor region 3 can be depleted in the longitudinal direction toward the second surface. For example, the impurity concentration of the N-type semiconductor region 3 differs from the impurity concentration of the P-type semiconductor region 5 by a factor of two or more. The impurity concentration of the N-type semiconductor region 3 is, for example, set to 1E18 cm⁻¹. -3 Or smaller. The N-type semiconductor region 3 preferably satisfies the following expression (2). In the following expression (2), the impurity concentration of the N-type semiconductor region 3 is set to impurity concentration Nd2, the impurity concentration of the P-type semiconductor region 5 is set to Na2, and the elementary charge is set to q. Furthermore, the dielectric constant of the semiconductor is set to... The potential difference between the PN junctions of the N-type semiconductor region 3 and the P-type semiconductor region 5 is set as potential difference V, and the depth of the N-type semiconductor region 3 is set as H. Here, depth refers to the thickness of the N-type semiconductor region 3 in the direction from the first surface to the second surface.

[0098] [Expression 2] The N-type semiconductor region 3 is shared by multiple adjacent avalanche diodes. The second isolation section 30 is composed of the N-type semiconductor region 3 and the P-type semiconductor region 4.

[0099] An N-type semiconductor region 2 with a lower impurity concentration than N-type semiconductor region 1 is preferably disposed between N-type semiconductor region 1 and P-type semiconductor region 4. This facilitates the movement of charge near N-type semiconductor region 2 to a position within N-type semiconductor region 1 closer to contact plug 6. N-type semiconductor region 2 can be configured to have the same impurity concentration as N-type semiconductor region 3.

[0100] exist Figure 4A and Figure 4BIn this design, N-type semiconductor region 2 and P-type semiconductor region 4 are in contact with each other, but they can be physically separated. Furthermore, to improve the breakdown voltage between N-type semiconductor region 2 and P-type semiconductor region 4, trench isolation can be applied between them. For example, STI (shallow trench isolation) can be applied between N-type semiconductor region 2 and P-type semiconductor region 4.

[0101] Notice, Figure 4A and Figure 4B The diagram illustrates a configuration in which a P-type semiconductor region 5 is arranged without an impurity concentration gradient; however, the P-type semiconductor region 5 can be a region with an impurity concentration gradient. For example, a configuration can be adopted in which the impurity concentration at depths deeper than a specific depth is set higher than the impurity concentration at a specific depth.

[0102] In this case, the impurity region of the first or second conductivity type used to adjust the electric field of the PN junction can be arranged directly below the N-type semiconductor region 1.

[0103] exist Figure 4A and Figure 4B In this configuration, two avalanche diodes aligned in a first or second direction share semiconductor region 3, but three or more avalanche diodes aligned in a first or second direction may share N-type semiconductor region 3.

[0104] In addition, Figure 4A and Figure 4B In the middle, on the third-party upward direction, the P-type semiconductor region 4 and the contact plug 7 are arranged between each N-type semiconductor region 1, but the P-type semiconductor region 4 and the contact plug 7 can be arranged sparsely.

[0105] exist Figure 3 and Figures 4A-4B In the top view, the distance between the four contact plugs 6 is equal to or greater than LC, and the distance between the four contact plugs 6 and the contact plug 7 is equal to or less than LC. L represents the distance between the contact plugs 7 aligned in the first direction, and LC is L / 2. In other words, in Figure 3 and Figures 4A-4BIn this configuration, contact plugs 7 are arranged at a distance equal to or less than LC relative to all four contact plugs 6. In this way, while the distances between the N-type semiconductor regions 1 and P-type semiconductor regions 4 of each avalanche diode are equally spaced, contact plugs 7 can be shared by the avalanche diodes. The distance between contact plugs can be, for example, the shortest distance between contact plugs. For example, in the case where multiple contact plugs are connected to the P-type semiconductor region 4 and multiple contact plugs 6 are connected to the N-type semiconductor region 1, it is sufficient for the contact plugs 6 and 7 at the shortest distance to satisfy the above expression. The shortest distance between the N-type semiconductor region 1 of each avalanche diode and the contact plug 7 closest to the N-type semiconductor region 1 is preferably set to an equal interval.

[0106] In addition, such as Figure 3 and Figures 4A-4B As shown, in the top view, contact plugs 7, 6, 7, 6, and 7 are arranged sequentially along the third direction. Along the cross-section of the third direction, contact plug 7, P-type semiconductor region 5, N-type semiconductor region 2, N-type semiconductor region 1, and N-type semiconductor region 2 are arranged sequentially. Next, contact plug 7, N-type semiconductor region 3, N-type semiconductor region 1, N-type semiconductor region 3, P-type semiconductor region 5, and contact plug 7 are arranged sequentially. In this manner, according to this embodiment, when contact plug 7 is shared by avalanche diodes, each structure is arranged symmetrically with each other in the third direction. This reduces the fluctuation of signal readout between avalanche diodes.

[0107] <Second Embodiment> Will use Figure 7 and Figure 8 The structure of the photoelectric conversion device according to the second embodiment is described. The second embodiment differs from the first embodiment in that the first isolation portion 20 is composed of an N-type semiconductor region 3 and a P-type semiconductor region 8 with a lower impurity concentration than the P-type semiconductor region 4. Items other than those described below can be constructed in a manner substantially similar to the first embodiment.

[0108] Also according to this embodiment, the height of the barrier formed by the second isolation portion 30 is higher than the height of the barrier formed by the first isolation portion 20. Furthermore, also according to this embodiment, the first isolation portion 20 is configured to be completely depleted.

[0109] The impurity concentration in region 8 of the P-type semiconductor is lower than that in region 4 of the P-type semiconductor.

[0110] The conditions for the complete depletion of the P-type semiconductor region 8 are shown in the following expression (3). Here, the impurity concentration of the N-type semiconductor region 3 is set to Nd, the impurity concentration of the P-type semiconductor region 8 is set to Na, and the elementary charge is set to q. Furthermore, the dielectric constant of the semiconductor is set to... The potential difference between the PN junction of the N-type semiconductor region 3 and the P-type semiconductor region 8 is set to V, and the length of the P-type semiconductor region 8 sandwiched between the N-type semiconductor region 3 is set to D.

[0111] [Expression 3] In the above expression (3), the dimension of D is [m], the dimension of q is [C], and the dimensions of Nd and Na are [m]. -3 ], The dimension of F is [F / m], and the dimension of V is [V]. That is, when the dimension of the above expression (3) is extracted, the following expression (4) holds.

[0112] [Expression 4] Furthermore, since Q = CV, [C] = [F][V], therefore, when the above expression (4) is expanded, the following expression (5) holds true.

[0113] [Expression 5] exist Figure 8 In this configuration, the N-type semiconductor region 3 and the P-type semiconductor region 8 are formed at the same depth, but the P-type semiconductor region 8 can be formed at a shallower location than the N-type semiconductor region 3. Furthermore, the P-type semiconductor region 8 is configured to form part of the first surface 40A, but it can also be formed away from the first surface 40A.

[0114] exist Figure 8 In the P-type semiconductor region 8, there is no impurity concentration gradient, but there may be an impurity concentration gradient in at least one of the directions parallel to the first surface 40A and the depth direction.

[0115] Similarly, according to this embodiment, as in the first embodiment, the pixel pitch can be reduced compared to Patent Document 1. Furthermore, since it can be configured such that the charge generated in the region between the first isolation portion 20 and the second surface is not read as a signal, sensitivity regions can be divided for each N-type semiconductor region 1, and signals can be separated.

[0116] <Third Embodiment> Will use Figures 9 to 11The structure of the photoelectric conversion device according to the third embodiment is described. The third embodiment differs from the first embodiment in that the first isolation portion 20 is composed of an N-type semiconductor region 3 and a trench isolation portion 9. Except for the items described below, the components can be constructed in a substantially similar manner to the first embodiment.

[0117] Figure 9 This is a partially enlarged top view of the pixel region of the photoelectric conversion device according to the third embodiment. Figure 10 and Figure 11 It is along Figure 9 A schematic cross-sectional view of section A-A'.

[0118] It can be done as follows Figure 10 The STI shown or as Figure 11 The DTI (deep trench isolation) shown forms a trench isolation portion 9. For example, one end of the trench isolation portion 9 is formed at a depth greater than that of the N-type semiconductor region 1.

[0119] At least one of the following: a dielectric material formed of oxide, polycrystalline silicon arranged via a dielectric film, and a metal, is embedded in a trench isolation portion 9.

[0120] Impurity regions of a first conductivity type can be disposed on the side of the trench isolation portion 9. These impurity regions of the first conductivity type are used to deactivate defects that may form at the interface between the trench isolation portion 9 and the semiconductor region 3.

[0121] Furthermore, in the case of a back-illuminated sensor, a groove can be formed from the second side.

[0122] Similarly, according to this embodiment, as in the first embodiment, the pixel pitch can be reduced compared to Patent Document 1. Furthermore, when the trench isolation portion 9 is formed using DTI, color mixing between adjacent pixels caused by the light emission from the avalanche diode can be reduced.

[0123] Fourth embodiment Will use Figure 12 and Figure 13 The structure of the photoelectric conversion device according to the fourth embodiment is described. According to the fourth embodiment, the avalanche diode is composed of an N-type semiconductor region 1, an N-type semiconductor region 10, and a P-type semiconductor region 11. The P-type semiconductor region 11 is also disposed at a deeper location than the N-type semiconductor regions 2 and 3 and the P-type semiconductor region 5. Furthermore, the P-type semiconductor regions 4 and 11 are interconnected via the P-type semiconductor region 5. The other aspects of the structure are similar to those of the first embodiment. Items other than those described below can be substantially similar to the structure of the first embodiment.

[0124] N-type semiconductor region 10 is a semiconductor region with a lower impurity concentration than N-type semiconductor region 1. Alternatively, N-type semiconductor region 10 may have a higher impurity concentration than N-type semiconductor region 3. When N-type semiconductor region 10 is formed between N-type semiconductor region 1 and P-type semiconductor region 11, the electric field strength generated between them can be adjusted. Furthermore, due to the arrangement of N-type semiconductor region 10, compared to the first embodiment, it is helpful to detect photocharge generated at greater depths and improves long-wavelength sensitivity.

[0125] The P-type semiconductor region 11 is continuously arranged in a specific cross-section from one position below a contact plug 7 to another position below a contact plug 7. Because of the arrangement of the P-type semiconductor region 11, unwanted signal charges that might be generated on the second surface 40B of the substrate can be prevented from being read into the N-type semiconductor region 1. Figure 12 In the middle, two groups of four avalanche diodes are arranged in a partitioned region separated by P-type semiconductor regions 4, 5 and 11.

[0126] P-type semiconductor region 5 can provide potential to P-type semiconductor region 11 via P-type semiconductor region 4. P-type semiconductor region 5 is a semiconductor region with a lower impurity concentration than P-type semiconductor region 4.

[0127] The p-type semiconductor region 11 can have a concentration gradient along the depth direction. Additionally, in Figure 12 In this process, a trench isolation section can be arranged between the P-type semiconductor region 4 and the N-type semiconductor region 2 to ensure voltage resistance.

[0128] Similarly, according to this embodiment, as in the first embodiment, the pixel pitch can be reduced compared to Patent Document 1. Furthermore, compared to the first embodiment, it facilitates the detection of photocharge generated at greater depths and improves long-wavelength sensitivity.

[0129] <Fifth Embodiment> Will use Figure 14 The structure of the photoelectric conversion device according to the fifth embodiment is described. According to the fifth embodiment, the first isolation portion 20 is composed of an N-type semiconductor region 3 and a P-type semiconductor region 8. Since the P-type semiconductor region 8 is similar to the P-type semiconductor region 8 of the second embodiment, its description will be omitted. Furthermore, since the structure other than the first isolation portion 20 is the same as that described according to the fourth embodiment, its description will also be omitted.

[0130] Similarly, according to this embodiment, as in the first embodiment, the pixel pitch can be reduced compared to Patent Document 1. Furthermore, compared to the first embodiment, it facilitates the detection of photocharge generated at greater depths and improves long-wavelength sensitivity.

[0131] <Sixth Embodiment> Will use Figure 15 and Figure 16 The structure of the photoelectric conversion device according to the sixth embodiment is described. Figure 15 This is a partially enlarged top view of the pixel region of the photoelectric conversion device according to the sixth embodiment. Figure 16 It is along Figure 15 A schematic cross-sectional view taken along line A-A'. According to the sixth embodiment, a P-type semiconductor region is arranged to physically separate the sensitivity regions of each pixel. Furthermore, the P-type semiconductor region 12 is arranged between the N-type semiconductor region 1 and the P-type semiconductor region 11, and the photoelectric conversion region 13 is arranged between the P-type semiconductor region 12 and the P-type semiconductor region 11. Additionally, the P-type semiconductor region 5 is arranged between the first isolation portion 20 and the P-type semiconductor region 11. The configuration is otherwise similar to that of the fourth embodiment. Items other than those described below can be substantially similar to the configuration of the fourth embodiment.

[0132] P-type semiconductor region 12 forms a PN junction with N-type semiconductor region 1. Avalanche multiplication may occur near this PN junction. In the cross-sectional view, P-type semiconductor region 12 is continuously arranged from one P-type semiconductor region 5 to another P-type semiconductor region 5.

[0133] The photoelectric conversion region 13 is arranged between the P-type semiconductor region 12 and the P-type semiconductor region 11.

[0134] The photoelectric conversion region 13 is composed of an N-type semiconductor region with an impurity concentration lower than that of the N-type semiconductor region 1 or a P-type semiconductor region with an impurity concentration lower than that of the P-type semiconductor region 5 and the P-type semiconductor region 11.

[0135] exist Figure 15 In the process, P-type semiconductor region 4 and N-type semiconductor region 2 are separated from each other, but P-type semiconductor region 4 and N-type semiconductor region 2 can be in contact with each other.

[0136] Similarly, according to this embodiment, as in the first embodiment, the pixel pitch can be reduced compared to Patent Document 1. Furthermore, according to this embodiment, since the photoelectric conversion region is physically separated from the P-type semiconductor region 5, it helps to reduce charge crosstalk. In addition, since the avalanche multiplication region can be reduced compared to the first embodiment, dark current can be reduced while maintaining sensitivity.

[0137] <Seventh Embodiment> Will use Figure 17 and Figure 18 The structure of the photoelectric conversion device according to the seventh embodiment is described. Figure 17 This is a partially enlarged top view of the pixel region of the photoelectric conversion device according to the seventh embodiment. Figure 18It is along Figure 17 A schematic cross-sectional view taken along line A-A'. According to the seventh embodiment, the first isolation portion 20 is composed of an N-type semiconductor region 3 and a P-type semiconductor region 8. Furthermore, P-type semiconductor regions 14 are arranged between P-type semiconductor regions 12 in a direction parallel to the first surface, and N-type semiconductor regions 15 are arranged between the photoelectric conversion regions. The rest of the construction is similar to that of the sixth embodiment. Except for the items described below, the items are substantially similar to those of the sixth embodiment.

[0138] In the top view, the P-type semiconductor region 14 is surrounded by the P-type semiconductor region 12. The P-type semiconductor region 14 is a P-type semiconductor region with a lower impurity concentration than the P-type semiconductor region 12. The P-type semiconductor region 14 and the N-type semiconductor region 1 form a PN junction, and the signal charge undergoes avalanche multiplication near the PN junction. Compared to the P-type semiconductor region 12, the P-type semiconductor region 14 has a lower potential height relative to electrons. Therefore, the generated signal charge is easily concentrated in the P-type semiconductor region 14 and easily crosses the PN junction interface between the P-type semiconductor region 14 and the N-type semiconductor region 1.

[0139] N-type semiconductor region 15 is disposed between P-type semiconductor region 14 and P-type semiconductor region 11. The impurity concentration of N-type semiconductor region 15 is lower than that of semiconductor region 1. When semiconductor region 14 is an N-type semiconductor region, the impurity concentration is set to be lower than that of semiconductor region 14.

[0140] Also according to this embodiment, similar to the first embodiment, the pixel pitch can be reduced compared to Patent Document 1. Furthermore, similar to the sixth embodiment, charge crosstalk can be suppressed. In addition, it helps to concentrate the charge in the N-type semiconductor region 1.

[0141] <Eighth Embodiment> Will use Figure 19 A photoelectric conversion device according to an eighth embodiment is described. In the photoelectric conversion device according to this embodiment, a... Figure 2 The substrate of the avalanche diode 201 of pixel 110 and the substrate on which the counter circuit 204 and the quenching element 202 are arranged are separated from each other. Then, the photoelectric conversion device is constructed by stacking and bonding the substrates.

[0142] According to this embodiment, each microlens is arranged to overlap with each avalanche diode in a top view.

[0143] Figure 19The diagram shows light incident from the second surface side, corresponding to the side of the unconnected contact plug. Therefore, the microlens 18 and color filter 19 are arranged on one side of the second surface of the substrate 16. When light is incident from the first surface side of the substrate 16, the microlens 18 and color filter 19 are arranged on the first surface side.

[0144] Similarly, according to this embodiment, as in the first embodiment, the pixel pitch can be reduced compared to Patent Document 1. Furthermore, by arranging the circuit section on one side of the substrate 17, the area of ​​the substrate 16 can be reduced.

[0145] exist Figure 19 In this embodiment, the construction other than the one described above adopts the avalanche diode construction described according to the seventh embodiment. Note that the avalanche diode construction described according to the first to sixth embodiments can also be used. In this case, compared with... Figure 19 Similarly, contact plug 6 is connected to the N-type semiconductor region 1 described in the various embodiments.

[0146] <Ninth Embodiment> Will use Figure 20 The photoelectric conversion device of the ninth embodiment is described. According to this embodiment, the photoelectric conversion device is configured such that light that has passed through a single microlens is incident on a plurality of avalanche diodes. Otherwise, the configuration is similar to that of the seventh embodiment.

[0147] According to this embodiment, depth detection can be performed while reducing the pixel pitch.

[0148] <Tenth Embodiment> Will use Figure 21 Examples of photoelectric conversion systems using the photoelectric conversion devices of various embodiments are described. They will be used... Figure 21 Describe invisible light detection systems and medical diagnostic systems such as PET, corresponding to examples of optical detection systems. For those with... Figures 1 to 20 Similar functional parts are given similar reference numerals, and their detailed descriptions will be omitted. Note that the pixels in this embodiment have TDC and memory instead of... Figure 2 The counter circuit is described below, wherein TDC is set to TDC 206 and memory is set to memory 207.

[0149] Figure 21 This is a block diagram describing the structure of an invisible light detection system. The invisible light detection system has a wavelength conversion unit 301 and a data processing unit 307, and also has multiple photoelectric conversion devices 1010.

[0150] The irradiated object 300 emits light in a wavelength band corresponding to invisible light. The wavelength conversion unit 301 receives the light in the wavelength band corresponding to invisible light emitted from the irradiated object 300 and emits visible light.

[0151] The avalanche diode 201 performs photoelectric conversion, and visible light emitted from the wavelength conversion unit 301 is incident on the avalanche diode 201. Then, the photoelectric conversion device 1010, via the control unit 208, the waveform shaping unit 203, and the TDC 206, stores a digital signal based on the signal according to the photoelectric conversion charge in the memory 207. Multiple photoelectric conversion devices 1010 can be formed as a single device or as an array of multiple devices.

[0152] The data processing unit 1207 performs signal processing on multiple digital signals stored in the memory 207 of the multiple photoelectric conversion devices 1010. Here, as a signal processing unit, it performs synthesis processing on multiple images obtained from the multiple digital signals.

[0153] Next, the construction of a medical diagnostic system such as PET will be described as a specific example of an invisible light detection system.

[0154] The subject, corresponding to the irradiated object 300, emits a pair of radiations from within the living organism. The wavelength conversion unit 301 constitutes a scintillator, and the scintillator emits visible light when the pair of radiations emitted from the subject is incident.

[0155] Visible light emitted from the scintillator is incident on an avalanche diode 201 for photoelectric conversion, and the photoelectric conversion device 1010, via a control unit 208, a waveform shaping unit 203, and a TDC 206, stores a digital signal based on the photoelectric conversion charge signal in a memory 207. In other words, the photoelectric conversion device 1010 is arranged to detect the arrival time of radiation pairs emitted from the subject and to detect visible light emitted from the scintillator to store the digital signal in the memory 207.

[0156] In the data processing unit 1207, signal processing is performed on the digital signals stored in the memory 207 of the multiple photoelectric conversion devices 1010. Here, synthesis processing such as image reconstruction is performed, and the signal processing unit forms an image of the inside of the living body of the subject using multiple images obtained from multiple digital signals.

[0157] <Eleventh Embodiment> Figure 22This is a block diagram illustrating the construction of a photoelectric conversion system 1200 according to this embodiment. The photoelectric conversion system 1200 of this embodiment includes a photoelectric conversion device 1215. Here, any photoelectric conversion device described according to the above embodiment can be applied to the photoelectric conversion device 1215. The photoelectric conversion system 1200 can be used as, for example, a camera system. Specific examples of camera systems include digital still cameras, digital video cameras, surveillance cameras, etc. Figure 22 An example of a digital still camera as a photoelectric conversion system 1200 is shown.

[0158] Figure 22 The photoelectric conversion system 1200 shown includes a photoelectric conversion device 1215, a lens 1213 for imaging an optical image of a subject onto the photoelectric conversion device 1215, an aperture 1214 for setting the amount of light passing through the lens 1213 to be variable, and a barrier 1212 for protecting the lens 1213. The lens 1213 and the aperture 1214 are an optical system for focusing light onto the photoelectric conversion device 1215.

[0159] The photoelectric conversion system 1200 includes a signal processing unit 1216 that processes the output signal from the photoelectric conversion device 1215. The signal processing unit 1216 performs various types of correction and compression on the input signal as needed, and performs signal processing operations on the signal to be output. The photoelectric conversion system 1200 also includes a buffer memory unit 1206 for temporarily storing image data and an external interface unit (external I / F unit) 1209 for communicating with an external computer or the like. Furthermore, the photoelectric conversion system 1200 includes a recording medium 1211 (such as a semiconductor memory) for recording or reading image data, and a recording medium control interface unit (recording medium control I / F unit) 1210 for recording to or reading from the recording medium 1211. The recording medium 1211 can be built into the photoelectric conversion system 1200 or can be detachably attached to the photoelectric conversion system 1200. In addition, wireless communication can be performed between the recording medium control I / F unit 1210 and the recording medium 1211, as well as between the external I / F unit 1209.

[0160] The photoelectric conversion system 1200 also includes an overall control and calculation unit 1208 that performs various types of calculations and controls the entire digital still camera, and a timing generation unit 1217 that outputs various types of timing signals to the photoelectric conversion device 1215 and the signal processing unit 1216. Here, timing signals, etc., can be input from the outside; it is sufficient that the photoelectric conversion system 1200 has at least the photoelectric conversion device 1215 and the signal processing unit 1216 that processes the output signals from the photoelectric conversion device 1215. As described in the fourth embodiment, the timing generation unit 1217 can be mounted on the photoelectric conversion device. The overall control and calculation unit 1208 and the timing generation unit 1217 can be configured to implement some or all of the control functions of the photoelectric conversion device 1215.

[0161] The photoelectric conversion device 1215 outputs an image signal to the signal processing unit 1216. The signal processing unit 1216 performs predetermined signal processing on the image signal output from the photoelectric conversion device 1215 and outputs image data. Furthermore, the signal processing unit 1216 generates an image using the image signal. Additionally, the signal processing unit 1216 can perform distance calculations on the signal output from the photoelectric conversion device 1215. Note that the signal processing unit 1216 or the timing generation unit 1217 can be mounted on the photoelectric conversion device. That is, the signal processing unit 1216 or the timing generation unit 1217 can be disposed on a substrate on which pixels are arranged, or it can have a structure disposed on other substrates. By using the photoelectric conversion devices of the above embodiments to construct an imaging system, an imaging system capable of obtaining higher quality images can be realized.

[0162] <Twelfth Embodiment> Will use Figures 23A-23B and Figure 24 This embodiment describes the photoelectric conversion system and the movable object. Figures 23A-23B This includes a schematic diagram illustrating a construction example of a photoelectric conversion system and a movable object according to this embodiment. Figure 24 This is a flowchart illustrating the operation of the photoelectric conversion system according to this embodiment. According to this embodiment, an example of a vehicle-mounted camera is shown as a photoelectric conversion system.

[0163] Figures 23A-23BAn example of a vehicle system and a photoelectric conversion system mounted thereon for imaging is shown. The photoelectric conversion system 1301 includes a photoelectric conversion device 1302, an image preprocessing unit 1315, an integrated circuit 1303, and an optical system 1314. The optical system 1314 images an optical image of the subject onto the photoelectric conversion device 1302. The photoelectric conversion device 1302 converts the optical image of the subject imaged by the optical system 1314 into an electrical signal. The photoelectric conversion device 1302 is any of the photoelectric conversion devices described in the various embodiments above. The image preprocessing unit 1315 performs predetermined signal processing on the signal output from the photoelectric conversion device 1302. The function of the image preprocessing unit 1315 can be embedded in the photoelectric conversion device 1302. At least two pairs of optical systems 1314, photoelectric conversion devices 1302, and image preprocessing units 1315 are provided in the photoelectric conversion system 1301, and the outputs from each pair of image preprocessing units 1315 are input to the integrated circuit 1303.

[0164] Integrated circuit 1303 is an integrated circuit for a camera system, and includes an image processing unit 1304 (including a memory 1305), an optical ranging unit 1306, a ranging calculation unit 1307, an object recognition unit 1308, and an anomaly detection unit 1309. The image processing unit 1304 performs image processing, such as development processing or defect correction, on the output signal of the image preprocessing unit 1315. The memory 1305 stores a single-shot image or the defect location of a camera pixel. The optical ranging unit 1306 focuses or measures the distance to the subject. The ranging calculation unit 1307 calculates ranging information based on multiple image data obtained from multiple photoelectric conversion devices 1302. The object recognition unit 1308 identifies subjects such as vehicles, roads, road signs, or people. When an anomaly is detected in the photoelectric conversion device 1302, the anomaly detection unit 1309 issues an anomaly alarm to the main control unit 1313.

[0165] The 1303 integrated circuit can be implemented using specially designed hardware, software modules, or a combination thereof. Additionally, integrated circuits can be implemented using FPGAs (Field-Programmable Gate Arrays), ASICs (Application-Specific Integrated Circuits), or combinations thereof.

[0166] The main control unit 1313 manages and controls the operation of the photoelectric conversion system 1301, vehicle sensor 1310, control unit 1320, etc. Alternatively, the photoelectric conversion system 1301, vehicle sensor 1310, and control unit 1320 may each have their own communication interface without the main control unit 1313, and may transmit and receive independently via a communication network (e.g., CAN standard).

[0167] Integrated circuit 1303 has the following function: by receiving control signals from main control unit 1313 or through its own control unit, it sends control signals or setting values ​​to photoelectric conversion device 1302.

[0168] The photoelectric conversion system 1301 is connected to the vehicle sensor 1310 and can detect its own vehicle driving status (such as vehicle speed, yaw rate, and rudder angle), as well as the external environment and the status of other vehicles and obstacles. The vehicle sensor 1310 is also configured to obtain distance information information about objects. Furthermore, the photoelectric conversion system 1301 is connected to the driver assistance control unit 1311, which performs various driver assistance functions (such as automatic steering, automatic cruise control, and collision avoidance). Specifically, regarding the collision determination function, the collision estimate and the presence or absence of a collision with other vehicles and obstacles are determined based on the detection results of the photoelectric conversion system 1301 and the vehicle sensor 1310. In this way, avoidance control is performed in the event of a collision and safety devices are activated upon collision.

[0169] Furthermore, the photoelectric conversion system 1301 is also connected to an alarm device 1312 that issues an alert to the driver based on the determination result of the collision determination unit. For example, if the collision probability is high according to the determination result of the collision determination unit, the main control unit 1313 performs vehicle control to avoid a collision or mitigate damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. The alarm device 1312 warns the user by emitting warnings such as audible alarms, displaying warning information on displays such as those on a car navigation system and dashboard, or providing vibrations to the seat belts or steering gear.

[0170] According to this embodiment, the area around the vehicle (e.g., the front or rear side) will be captured by the photoelectric conversion system 1301. Figure 23B An example of the arrangement of the photoelectric conversion system 1301 in the case where the front side of the vehicle is to be photographed by the photoelectric conversion system 1301 is shown.

[0171] Two photoelectric conversion devices 1302 are arranged on the front side of the vehicle 1300. Specifically, they are preferably arranged to obtain distance information between the vehicle 1300 and the object to be photographed and to determine the probability of a collision, wherein the center line relative to the front-rear orientation or shape (e.g., vehicle width) of the vehicle 1300 is considered an axis of symmetry, and the two photoelectric conversion devices 1302 are arranged linearly symmetrically with respect to this axis of symmetry. Furthermore, the photoelectric conversion devices 1302 are preferably arranged in a position where the driver's field of vision will not be obstructed when the driver visually identifies the external conditions of the vehicle 1300 from the driver's seat. The alarm device 1312 is preferably arranged so that the driver can easily see it.

[0172] Next, we will use Figure 24Describes the defect detection operation of the photoelectric conversion device 1302 in the photoelectric conversion system 1301. According to... Figure 24 The steps S1410 to S1480 shown are used to perform defect detection operations on the photoelectric conversion device 1302.

[0173] Step S1410 is a setting step performed when the photoelectric conversion device 1302 is started. That is, the setting for the operation of the photoelectric conversion device 1302 is sent from outside the photoelectric conversion system 1301 (e.g., the main control unit 1313) or inside the photoelectric conversion system 1301, and the camera operation and defect detection operation of the photoelectric conversion device 1302 are started.

[0174] Subsequently, in step S1420, a pixel signal is obtained from the effective pixel. Furthermore, in step S1430, an output value from the defect detection pixel provided for detecting defects is obtained. As in the effective pixel, the defect detection pixel similarly includes a photoelectric conversion unit. A predetermined voltage is written into this photoelectric conversion unit. The pixel used for detecting defects outputs a signal corresponding to the voltage written into the photoelectric conversion unit. Note that steps S1420 and S1430 can be reversed.

[0175] Subsequently, in step S1440, an appropriateness determination is performed between the expected output value of the defect detection pixel and the actual output value from the defect detection pixel. As a result of the appropriateness determination in step S1440, if the expected output value matches the actual output value, the processing step proceeds to step S1450, it is determined that the imaging operation is proceeding normally, and the processing step proceeds to step S1460. In step S1460, the pixel signals in the scan line are sent to memory 1305 and initially stored. Thereafter, the processing step returns to step S1420, and the defect detection operation continues. On the other hand, as a result of the appropriateness determination in step S1440, if the expected output value does not match the actual output value, the processing step proceeds to step S1470. In step S1470, it is determined that an abnormality exists in the imaging operation, and an alarm is issued to the main control unit 1313 or the alarm device 1312. The alarm device 1312 causes the display unit to display that an abnormality has been detected. Subsequently, the photoelectric conversion device 1302 stops in step S1480, and the operation of the photoelectric conversion system 1301 ends.

[0176] Note that, according to this embodiment, an example of a loop flowchart for each line has been illustrated, but defect detection operations can be performed for multiple loop flowcharts or for each frame. In step S1470, the alarm can be notified to the outside of the vehicle via a wireless network.

[0177] Furthermore, while this embodiment describes control to avoid collisions with other vehicles, it can also be applied to control of autonomous driving following other vehicles, control of autonomous driving without deviating from the driving lane, and so on. Moreover, the photoelectric conversion system 1301 is not limited to vehicles such as its own vehicle; it can also be applied to movable objects (movable devices) such as ships, aircraft, or industrial robots. Furthermore, this embodiment can be applied not only to movable objects but also to instruments that widely utilize object recognition, such as intelligent transportation systems (ITS).

[0178] The photoelectric conversion device of the present invention can have a structure that can further obtain various types of information such as distance information.

[0179] <Thirteenth Embodiment> Figure 25 This is a block diagram illustrating an example of the construction of a distance image sensor corresponding to an electronic instrument utilizing a photoelectric conversion device described in the above embodiments.

[0180] like Figure 25 As shown, the distance image sensor 401 is configured to include an optical system 402, a photoelectric conversion device 403, an image processing circuit 404, a monitor 405, and a memory 406. Furthermore, when light is projected from the light source device 411 onto the subject and the light reflected from the surface of the subject (modulated light or pulsed light) is received, the distance image sensor 401 can obtain a distance image based on the distance to the subject.

[0181] The optical system 402 is configured to have one or more lenses and guide image light (incident light) from the subject to the photoelectric conversion device 403 to form an image on the light receiving surface (sensor section) of the photoelectric conversion device 403.

[0182] The photoelectric conversion device in the above embodiments is used as photoelectric conversion device 403, and a distance signal indicating the distance obtained from the light receiving signal output from photoelectric conversion device 403 is provided to image processing circuit 404.

[0183] The image processing circuit 404 performs image processing based on the distance signal provided from the photoelectric conversion device 403 to construct a distance image. The distance image (image data) obtained through image processing is then provided to the monitor 405 for display or to the memory 406 for storage (recording).

[0184] In the distance image sensor 401 configured in this way, by applying the above-mentioned photoelectric conversion device along with improvements in the characteristics of the pixels, for example, a more accurate distance image can be obtained.

[0185] <Fourteenth Embodiment> The technology disclosed herein (the Technology) can be applied to a variety of products. For example, the Technology disclosed herein can be applied to endoscopic surgical systems.

[0186] Figure 26 This is a diagram illustrating an example of a schematic construction of an endoscopic surgical system to which the technology (the present technology) can be applied.

[0187] Figure 26 The illustration shows an operator (doctor) 1131 performing surgery on a patient 1132 on a bed 1133 using an endoscopic surgery system 1000. As shown, the endoscopic surgery system 1000 consists of an endoscope 1100, surgical instruments 1110, and a trolley 1140 loaded with various types of devices for endoscopic surgery.

[0188] Endoscope 1100 comprises a tube 1101 and a camera 1102 connected to the proximal end of the tube 1101. The tube 1101 has a region of a predetermined length from the distal end for insertion into the body cavity of the patient 1132. In the example shown in the figure, an endoscope 1100 configured as a rigid endoscope with a rigid tube 1101 is illustrated; however, endoscope 1100 can be configured as a so-called flexible endoscope with a flexible tube.

[0189] An opening for fitting the objective lens is provided at the distal end of the endoscope tube 1101. A light source device 1203 is connected to the endoscope 1100, and the light generated by the light source device 1203 is guided by a light guide extending inside the endoscope tube 1101 to the distal end of the tube, and then emitted through the objective lens towards the object being observed within the body cavity of the patient 1132. Note that the endoscope 1100 can be a direct-viewing mirror, an oblique-viewing mirror, or a side-viewing mirror.

[0190] An optical system and a photoelectric conversion device are disposed inside the camera 1102, and reflected light (observation light) from the object being observed is focused onto the photoelectric conversion device by the optical system. The photoelectric conversion device performs photoelectric conversion on the observation light and generates an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The photoelectric conversion device described according to the above embodiments can be used as a photoelectric conversion device. The image signal is sent as RAW data to the camera control unit (CCU: camera control unit) 1201.

[0191] The CCU 1201 consists of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and controls the operation of the endoscope 1100 and the display device 1202 as a whole. In addition, the CCU 1201 receives image signals from the camera 1102 and applies various types of image processing to the image signals for displaying images based on the image signals, such as image enhancement processing (de-mosaic processing).

[0192] The display device 1202 displays an image based on an image signal that has undergone image processing by the CCU 1201, under control from the CCU 1201.

[0193] The light source device 1203 is composed of a light source such as an LED (light-emitting diode) and provides illumination light to the endoscope 1100 for imaging the surgical site, etc.

[0194] Input device 1204 is an input interface for the endoscopic surgery system 1000. Users can input commands and various types of information into the endoscopic surgery system 1000 via input device 1204.

[0195] The surgical tool control device 1205 controls the drive of the energy surgical tool 1112 used for tissue cauterization, incision, vascular sealing, etc.

[0196] The light source device 1203 that provides illumination light to the endoscope 1100 for imaging the surgical site is composed of a white light source, such as an LED, a laser light source, or a combination thereof. When the white light source is a combination of RGB laser light sources, the white balance of the captured image can be adjusted within the light source device 1203 because the output intensity and timing of each color (wavelength) can be controlled with high precision. Furthermore, in this case, lasers from each RGB laser light source are emitted to the object of observation in a time-division manner, and the driving of the imaging element of the camera 1102 is controlled synchronously with the illumination timing, allowing for the capture of images corresponding to each of the RGB values ​​in a time-division manner. According to this method, color images can be obtained even when a color filter is not provided in the imaging element.

[0197] Furthermore, the drive of the light source device 1203 can be controlled to change the intensity of the output light at predetermined intervals. The drive of the imaging element of the camera 1102 is controlled synchronously with the timing for changing the light intensity, thereby acquiring images in a time-division manner and synthesizing the images to generate high dynamic range images without so-called black defects or white halos.

[0198] Furthermore, the light source device 1203 can be configured to provide light within a predetermined wavelength band corresponding to special light observation. In special light observation, for example, the wavelength dependence of light absorption within the body system is utilized. Specifically, a predetermined tissue, such as a mucosal surface portion, is imaged with high contrast when a narrow band of light is emitted compared to the illumination light (i.e., white light) used in normal observation. Alternatively, fluorescence observation can be performed in special light observation, wherein an image is obtained by observing the fluorescence generated upon emission of excitation light. In fluorescence observation, fluorescence from the body system can be observed by emitting excitation light into the body system in such a manner as by locally injecting a reagent such as indocyanine green (ICG) into the body system and also emitting excitation light corresponding to the fluorescence wavelength of the reagent into the body system. The light source device 1203 can be configured to provide narrow band light and / or excitation light corresponding to the aforementioned special light observation.

[0199] Figure 27 It is shown Figure 26 A block diagram illustrating an example of the functional configuration of the camera 1102 and CCU 1201.

[0200] Camera 1102 includes a lens unit 1401, a photoelectric conversion device 1402, a drive unit 1403, a communication unit 1404, and a camera control unit 1405. CCU 1201 includes a communication unit 1411, an image processing unit 1412, and a control unit 1413. Camera 1102 and CCU 1201 are connected via a transmission cable 1400 to communicate with each other.

[0201] The lens unit 1401 is an optical system disposed in the connection portion with the lens barrel 1101. Observation light obtained from the distal end of the lens barrel 1101 is guided to the camera 1102 and incident on the lens unit 1401. The lens unit 1401 is composed of a combination of multiple lenses, including a zoom lens and a focusing lens.

[0202] The photoelectric conversion devices described in the above embodiments can be used as photoelectric conversion device 1402. Photoelectric conversion device 1402 can be composed of a single photoelectric conversion device or multiple photoelectric conversion devices. When photoelectric conversion device 1402 is composed of multiple photoelectric conversion devices, for example, each photoelectric conversion device can generate image signals corresponding to each of the RGB values, and these image signals can be synthesized to obtain a color image. Alternatively, photoelectric conversion device 1402 can be configured to have a pair of photoelectric conversion devices for obtaining image signals for the right eye and left eye respectively corresponding to 3D (dimensional) display. When performing 3D display, the operator 1131 can more accurately determine the depth of living tissue at the surgical site. Note that when photoelectric conversion device 1402 is composed of multiple photoelectric conversion devices, a system of multiple lens units 1401 can be provided corresponding to each photoelectric conversion device.

[0203] The drive unit 1403 is composed of an actuator, and under the control of the camera control unit 1405, it moves the zoom lens and focusing lens of the lens unit 1401 a predetermined distance along the optical axis. In this way, the magnification and focus of the image captured by the photoelectric conversion device 1402 can be appropriately adjusted.

[0204] The communication unit 1404 is composed of a communication device configured to transmit and receive various types of information with the CCU 1201. The communication unit 1404 transmits the image signal obtained from the photoelectric conversion device 1402 as RAW data to the CCU 1201 via the transmission cable 1400.

[0205] Furthermore, the communication unit 1404 receives control signals from the CCU 1201 for controlling the drive of the camera 1102 and provides the control signals to the camera control unit 1405. The control signals include, for example, information related to shooting conditions, such as information indicating the frame rate specifications of the captured image, information indicating the exposure value specifications during shooting, and / or information indicating the magnification and focus specifications of the captured image.

[0206] Note that the aforementioned imaging conditions, such as frame rate, exposure value, magnification, and focus, can be appropriately specified by the user or automatically set by the control unit 1413 of the CCU 1201 based on the acquired image signal. In the latter case, the so-called AE (automatic exposure), AF (automatic focus), and AWB (automatic white balance) functions are installed on the endoscope 1100.

[0207] The camera control unit 1405 controls the driving of the camera 1102 based on the control signal received from the CCU 1201 via the communication unit 1404.

[0208] The communication unit 1411 is composed of a communication device configured to send and receive various types of information with the camera 1102. The communication unit 1411 receives image signals transmitted from the camera 1102 via the transmission cable 1400.

[0209] In addition, the communication unit 1411 sends control signals for controlling the camera 1102 to the camera 1102. The image signal and control signal can be transmitted via electrical communication, optical communication, etc.

[0210] The image processing unit 1412 applies various types of image processing to the image signal corresponding to the RAW data sent from the camera 1102.

[0211] The control unit 1413 performs various types of control related to the imaging of the surgical site by the endoscope 110 and the display of the images obtained by imaging the surgical site. For example, the control unit 1413 generates control signals for controlling the drive of the camera 1102.

[0212] Furthermore, the control unit 1413, based on the image signal processed by the image processing unit 1412, causes the display device 1202 to display captured images of the surgical site, etc. At this time, the control unit 1413 can use various types of image recognition technology to identify various types of objects in the captured images. For example, the control unit 1413 can identify surgical instruments such as forceps, specific living tissue sites, bleeding, and fogging when using the energy surgical tool 1112 by detecting the shape and color of the edges of objects included in the captured images. When the display device 1202 displays the captured images, the control unit 1413 can use the recognition results to overlay various types of surgical assistance information onto the image of the surgical site. When surgical assistance information is overlaid and presented to the operator 1131, the burden on the operator 1131 can be reduced, and the operator 1131 can perform the surgery with certainty.

[0213] The transmission cable 1400 connecting the camera 1102 and the CCU 1201 is an electrical signal cable corresponding to electrical signal communication, an optical fiber corresponding to optical communication, or a composite cable thereof.

[0214] In the example shown here, wired communication is achieved using transmission cable 1400, but wireless communication between camera 1102 and CCU 1201 is also possible.

[0215] Examples of endoscopic surgical systems to which the technology according to this disclosure can be applied have been described above. The technology according to this disclosure can be applied to the endoscope 1100, camera 1102 (photoelectric conversion device 1402), etc., in the above-described configuration. By applying the technology according to this disclosure to the endoscope 1100, camera 1102 (photoelectric conversion device 1402), etc., the effects of afterpulses generated by avalanche multiplication can be reduced.

[0216] Note that an endoscopic surgical system is described in this document as an example, but the techniques disclosed herein can be applied to other systems, such as microsurgical systems.

[0217] <Fifteenth Embodiment> Will use Figures 28A-28C and Figure 29 A photoelectric conversion system according to the fifteenth embodiment is described.

[0218] Figure 28A This diagram illustrates the driving force of a Time-of-Flight (ToF) time-gate. Multiple laser pulses are emitted towards the object being measured. The light reflected from the object and the time delay... The photons are detected together by the detector (the aforementioned photoelectric conversion device). In a typical time-gating measurement, the gate window (the light detection period of the photoelectric conversion device) is gradually shifted for scanning, and information from consecutive frames is obtained. At each gate window position, the photon count is integrated N times. While finer gate scanning improves temporal resolution, it also increases measurement time.

[0219] Figure 28B The measurement results, converted to a histogram, are shown. The histogram includes the background photon count and the dark current component value when the reflected laser pulse is present outside the door / window. In the histogram, when the peak intensity of the reflected light is greater than the count value of the background component, the profile of the reflected light count is a rectangular distribution. This rectangular distribution has a width corresponding to the length of the door / window. The delay time can be obtained from the rise or fall of the count value profile. t. The distance L from the object to the detector is given by L=c Calculate using t / 2. Where c represents the speed of light.

[0220] Figure 28C A time-gated SPAD pixel is shown. A transistor serving as a quenching element 202 is connected to an avalanche diode 201. The quenching element 202 is configured to suppress electron avalanche (avalanche breakdown). When the global gate switch 280 is turned on from off, the output signal from the avalanche diode 201 is selectively output to the memory 281. The gate control pulse is approximately a few nanoseconds and is controlled synchronously with the laser pulse irradiation. The memory 281, configured for each pixel, is located in... Figure 2The counter circuit 204 is internal, and the signal stored in the memory 281 is read via the output section 282. Note that a specific voltage can be applied to the gate voltage VQ of the quenching element 202. In addition, in order to force the avalanche diode 201 to be recharged before the global gate switch 280 becomes on, a pulse signal can be driven to input a pulse signal to VQ.

[0221] Figure 29 The door-window curve, reflected light distribution, and detection intensity are shown. The detection intensity h(t) corresponds to the convolution calculation of two functions (convolution). That is, the convolution of the door-window curve f(t) and the reflected light distribution g(t) corresponds to the detection intensity h(t). Figure 29 In the diagram, the top image shows a single reflection peak, while the bottom image shows two reflection peaks. In real-world measurement environments, the detected intensity curves can have complex shapes. For example, this is the case where a laser is emitted towards an object via a semi-transparent object (semi-reflective object). In this situation, both the light reflected by the semi-transparent object, such as glass or transparent plastic, and the light transmitted through the semi-transparent object and emitted towards the object are detected. Figure 29 The bottom figure illustrates the measurement example described above. Since the detection intensity h(t) is the measurement data and the door / window curve f(t) is known, the reflected light distribution g(t) can be obtained through deconvolution calculation. When the reflected light distribution g(t) is available, the distance information of the semi-transparent object or the object itself can be obtained, or only the distance information of the object can be separated.

[0222] This embodiment is a distance image sensor of the type described in the thirteenth embodiment, and the above-mentioned detection and distance information calculation are performed by a photoelectric conversion device 403. An image processing circuit 404 forms a distance image based on the obtained distance signal. The formed distance image is provided to a monitor 405 for display or to a memory 406 for storage.

[0223] (Experimental Example) Figures 30A-30C An experimental example of the fifteenth embodiment is shown.

[0224] Figure 30A This diagram illustrates the experimental setup. A pulsed laser beam is emitted at 40 MHz from a 510 nm laser 320. The object 350 is illuminated using the pulsed laser beam diffused by a light diffusion member 330. The SPAD camera 310 and the laser 320 are configured to be synchronized with each other via a pulse generator 325. A transparent plate 340 made of plastic is positioned between the SPAD camera 310 and the object 350.

[0225] Figure 30B and Figure 30CThe diagram shows the relationship between the position of the door window (door position) and the detected count value in the pixel corresponding to a specific position of object 350. Figure 30B The curve is without the transparent plate 340. Figure 30C This is the curve with the transparent plate 340 set. Figure 30C The curve has two stages of ascent (position 40 and position 100). This two-stage ascent corresponds to double reflection from the transparent plate 340 and the object 350. Figures 30A-30C The reflected light distribution is obtained from the measurement curve, and distance information is obtained from the reflected light distribution. Distance information and light intensity distribution information are obtained from each pixel arranged in two dimensions, and three-dimensional imaging can be performed when the light intensity distribution information is displayed in monochrome and the distance information is displayed in color.

[0226] Furthermore, when distance information is obtained, 3D imaging within a specified distance range can be performed. For example, signals closer to the SPAD camera and signals farther from the SPAD can be separated to form individual 3D images.

[0227] For example, when the transparent panel is a vehicle window and it is desired to observe only objects behind the window, when forming a distance image of both the window and the object using a commonly used indirect Time-of-Flight (ToF) method, errors may occur in distance measurement due to the reflection of the window. In this case, as described in the twelfth embodiment, unintended control may occur when controlling a movable object (e.g., a car) via distance measurement, and safety issues may arise. According to this embodiment, since three-dimensional imaging can be performed separately for objects at different distances from the camera, such concerns can be reduced.

[0228] <Sixteenth Embodiment> Will use Figures 31A-31B The photoelectric conversion device corresponding to the sixteenth embodiment is described.

[0229] Figure 31A It's a circuit diagram of a pixel. Specifically, Figure 31A It shows Figure 2 The photoelectric conversion unit 101 has a circuit. The quenching transistor M is controlled by VQR. Q The avalanche current generated in the avalanche diode is converted into voltage via a gate transistor M controlled by VG. G The voltage pulse is transmitted to the pull-down transistor M. PD As a result, the feedback transistor M FB Entering the cutoff state. In this way, transistor M is quenched. Q The source of the transistor enters a disconnected state to disable the quenching function in the SPAD. Pull-down transistor MPD The drain voltage is maintained close to ground voltage (ground voltage) for a sufficiently long period until the signal across the entire chip is read. For the next photodetection, it is charged to the potential of VDDH-VTH-VDSAT. After this, the feedback transistor M... FB The transistor M, controlled by VSW, returns from the off state to the on state. SW Connected to pull-down transistor M PD The drain and transistor M RS The source, and transistor M RS The source of transistor M is pre-charged to VDD-VTH via the control signal VRES. When VSEL is applied to transistor M... SEL When it enters the conduction state, transistor M PDO Used to drop down an entire column. For example, rows are selected in order.

[0230] Here, transistor M is shown as a dashed line. RS Transistor M PDO and transistor M SEL These transistors are shared by multiple pixels (multiple avalanche diodes). Specifically, these transistors are shared by four pixels arranged in two rows and two columns (four avalanche diodes). Because multiple pixels share the same circuitry, more avalanche diodes can be arranged in the same area. According to the above embodiment, as... Figures 5A-5C As shown, when the barrier formed by the first isolation portion 20 is set lower than the barrier formed by the second isolation portion 30, the pixel size decreases, and crosstalk is reduced. Furthermore, by using the pixel circuit of this embodiment, since the pixel size can be further reduced during arraying, a SPAD array sensor with more pixels can be provided.

[0231] The pixels in this embodiment have a feedback loop that prevents subsequent avalanche within a frame. The feedback loop suppresses current from the cathode voltage node VOP. Since counts exceeding 100,000 can affect power consumption, this can be considered advantageous in large-area arrays.

[0232] Figure 31B This diagram illustrates the driving method. Exposure begins when VQR and VG transition from H level to L level, and a subframe exposure occurs when VQR and VG transition from L level to H level. The subframe exposure period is essentially defined as the time interval from the timing of VQR transitioning from H level to L level to the timing of VG transitioning from H level to L level. By repeating the subframe interval multiple times, sufficient photon counts can be obtained even for weak light signals. During the readout period, VRES is first set to H level to reset M. RS The source terminal. Next, set VSW to H level to write the output signal to M.RS The source terminal is determined. During the exposure period, the detection of photons corresponds to the L level, while the absence of photons corresponds to the H level. Furthermore, VSEL is set to the H level to output the pixel signal to the vertical signal line. After the readout is complete, all VRES, VSW, VQR, and VG are simultaneously set to the H level for a reset.

[0233] <Seventeenth Embodiment> Will use Figure 32 and Figures 33A to 35B A filter corresponding to the photoelectric conversion device of the seventeenth embodiment is described. Figure 32 It is a graph representing the spectral transmittance of each filter. Figures 33A to 35B An example of the specific arrangement of filters in the photoelectric conversion device of this embodiment is shown.

[0234] Such filters, used to transmit light of a specific wavelength component to an avalanche photodiode arranged on a substrate, can be incorporated into a photoelectric conversion device. Examples of filters include color filters (also referred to as CF filters), infrared filters, and infrared cutoff filters. These filters can be used individually or in combination.

[0235] A filter (CF) is, for example, a filter used to transmit visible light such as red, green, or blue. Hereinafter, red, green, and blue will be represented as R, G, and B. Furthermore, a pixel with a CF having the color 'R' will be represented as an R pixel, a pixel with a CF having the color 'G' will be represented as a G pixel, and a pixel with a CF having the color 'B' will be represented as a B pixel. Additionally, when representing R, G, and B pixels together, they can be represented as RGB pixels. Furthermore, infrared light will be represented as IR. A pixel with a filter for transmitting IR will be represented as an IR pixel.

[0236] Figure 32 The spectral transmittance of the filter is shown. Figure 32 This is a graph where the horizontal axis represents wavelength (in nm) and the vertical axis represents spectral transmittance (in %). First, the wavelength range of visible light is generally greater than or equal to 400 nm and less than 700 nm, while the wavelength range of infrared light is greater than or equal to 750 nm and less than or equal to 1 mm. Here, the spectral transmittance of an IR filter is 50% or greater in the wavelength range of at least 700 nm or greater, and less than 50% in the wavelength range less than 700 nm. That is to say, an IR filter is a filter that primarily transmits infrared light while blocking visible light. Figure 32As shown by the solid line IR in the diagram, the spectral transmittance of an IR filter indicates 90% or greater near 740 nm, but does not exceed 50% at wavelengths less than or equal to 700 nm. On the other hand, the spectral transmittance of a visible light filter is 50% or greater in the wavelength range less than 700 nm. In other words, a visible light filter is a filter that primarily transmits visible light. A visible light filter only needs to transmit light in the visible light wavelength range below the infrared wavelength (e.g., light with wavelengths less than 700 nm). Figure 32 As shown by the solid lines R, G, and B, the spectral transmittance of each visible light filter exceeds 50% in specific wavelengths less than 700 nm. For example, the peak spectral transmittance of the R filter is at approximately 650 nm, that of the G filter is at approximately 550 nm, and that of the B filter is at approximately 450 nm. Visible light filters can partially transmit light in the infrared wavelength range, but to remove the influence of infrared light, visible light filters can be designed to block light in the infrared wavelength range, such as light greater than or equal to 700 nm. That is, visible light filters can function as so-called IR cutoff filters. Furthermore, visible light filters can include infrared cutoff filters, which block light greater than or equal to 700 nm. Figure 32 The range of transmitted light from the IR cutoff filter is illustrated. The materials of each filter can be organic or inorganic. Note that opacity or lack of light transmission is not limited to a 100% opaque state. For example, such a state refers to a state where more than 50% of the light is transmitted.

[0237] Figure 33A An example arrangement with a so-called Bayer array is described. The CF ratio of R:G:B is 1:2:1.

[0238] Figure 33B An example of the arrangement of RGBW12 CFs is shown. According to this array, the CFs are arranged in a ratio of R:G:B:W = 1:2:1:12 across 4 In a 4-pixel array, W refers to a white pixel that is not surrounded by CF (color filter). The W pixels are arranged to be adjacent to any one of the R, G, and B pixels corresponding to the color pixels in the vertical, horizontal, and diagonal directions in the top view. That is, each of the R, G, and B pixels is surrounded by 8 W pixels. The W pixels occupy 3 / 4 of all pixels. Each of the RGB pixels corresponding to the color pixels is surrounded by W pixels, and the interpolation accuracy used to interpolate the signal of the W pixels is improved for each of the R, G, and B pixel signals.

[0239] Figure 34 It uses IR pixels instead Figure 33BAn example of the arrangement of W pixels. Such a filter arrangement can be used.

[0240] In addition, such as Figures 35A-35B As shown, the pixels can be arranged in a honeycomb shape. Figures 35A-35B In the diagram, IR pixels are arranged, but W pixels can also be used instead of IR pixels.

[0241] In this way, the photoelectric conversion device according to this embodiment can employ various filter arrangements.

[0242] Various modifications can be made to this invention, and it is not limited to the embodiments described above. For example, examples of adding a portion of the construction of any embodiment to other embodiments, and examples of performing substitutions that utilize a portion of the construction of other embodiments, are also embodiments of this invention.

[0243] Note that the above embodiments are merely examples of implementations of the present invention and should not be construed as limiting the scope of the invention to these embodiments. That is, the present invention can be implemented in various forms without departing from its technical concept or its main features.

[0244] For example, the seventeenth embodiment shows an example of arranging a filter, but the photoelectric conversion device of each embodiment can be used as a photoelectric conversion device for photoelectric conversion of monochromatic light without arranging a CF or IR cutoff filter or a visible light cutoff filter.

[0245] This application claims priority to Japanese Patent Application No. 2020-015607, filed January 31, 2020; Japanese Patent Application No. 2020-108754, filed June 24, 2020; and Japanese Patent Application No. 2020-183448, filed November 2, 2020, the entire contents of which are incorporated herein by reference.

Claims

1. A photoelectric conversion device, comprising: The first avalanche diode includes a first semiconductor region of a first conductivity type in which the majority carriers are charge carriers of the same conductivity type as the signal charge. The second avalanche diode includes a second semiconductor region of the first conductivity type and is arranged adjacent to the first avalanche diode. And a third avalanche diode, which includes an eighth semiconductor region of a first conductivity type and is arranged adjacent to the second avalanche diode, wherein In the top view, the first avalanche diode and the second avalanche diode are aligned in a first direction, and the second avalanche diode and the third avalanche diode are aligned in a second direction orthogonal to the first direction. The first isolation portion is disposed between the first semiconductor region and the second semiconductor region. The first isolation portion is composed of a third semiconductor region of the first conductivity type. The seventh semiconductor region of the second conductivity type is arranged in the top view at a location that overlaps with and is deeper than the third semiconductor region. The second conductivity type is a conductivity type different from the first conductivity type. The third semiconductor region and the seventh semiconductor region form a PN junction, and The impurity concentration in the third semiconductor region is lower than that in the seventh semiconductor region. Wherein, no semiconductor region of the second conductivity type is arranged between the first semiconductor region and the second semiconductor region, and In the top view, a contact plug that provides a potential to a node of the first avalanche diode is arranged between the first semiconductor region and the eighth semiconductor region.

2. The photoelectric conversion device according to claim 1, wherein, The third semiconductor region is in contact with the first semiconductor region and the second semiconductor region.

3. The photoelectric conversion device according to claim 1, wherein, The third semiconductor region is shared by the first avalanche diode and the second avalanche diode.

4. The photoelectric conversion device according to claim 3, wherein, The impurity concentration in the third semiconductor region is lower than that in the first semiconductor region.

5. The photoelectric conversion device according to claim 1, wherein, The first semiconductor region and the second semiconductor region are disposed on the substrate. A memory or counter circuit configured to detect an avalanche current generated based on a signal from the first avalanche diode is disposed on a second substrate different from the said substrate, and The substrate and the second substrate are stacked.

6. The photoelectric conversion device according to claim 1, wherein, A trench isolation is formed between the first semiconductor region and the second semiconductor region.

7. The photoelectric conversion device according to claim 6, wherein, One end of the trench isolation is formed to be deeper than the first semiconductor region.

8. The photoelectric conversion device according to claim 1, wherein, The first avalanche diode, the second avalanche diode, and the third avalanche diode operate in Geiger mode.

9. The photoelectric conversion device according to claim 1, further comprising: Color filters, among which Light passing through the color filter is incident on the first avalanche diode and the second avalanche diode.

10. The photoelectric conversion device according to claim 1, wherein, The ninth semiconductor region of the second conductivity type is disposed between the first semiconductor region and the eighth semiconductor region. The fourth semiconductor region is disposed between the first semiconductor region and the second semiconductor region. The contact plug is connected to the ninth semiconductor region, and The impurity concentration in the fourth semiconductor region is lower than that in the ninth semiconductor region.

11. The photoelectric conversion device according to claim 10, wherein, The contact plug is formed on the first surface of the substrate, and Light is incident from the second side of the substrate opposite to the first side.

12. The photoelectric conversion device according to claim 11, wherein, The first distance between the first semiconductor region and the second semiconductor region is shorter than the second distance between the first semiconductor region and the eighth semiconductor region.

13. The photoelectric conversion device according to claim 12, wherein, The first distance is at least 1 / 8 times the second distance.

14. The photoelectric conversion device according to claim 10, further comprising: At least one of a memory, a time-to-digital converter, and a counter is arranged corresponding to and configured to detect the avalanche current generated by avalanche multiplication in the first avalanche diode, wherein... In the top view, the contact plug that provides potential to the node is not positioned between the first semiconductor region and the second semiconductor region. The contact plug and the ninth semiconductor region are shared by the first avalanche diode, the second avalanche diode, and the third avalanche diode.

15. The photoelectric conversion device according to claim 14, further comprising: The second contact plug provides a potential to the first semiconductor region, wherein the distance between the second contact plug and the contact plug, the distance between the third contact plug providing a potential to the second semiconductor region and the contact plug, and the distance between the fourth contact plug providing a potential to the eighth semiconductor region and the contact plug are all equal to each other.

16. A photoelectric conversion device, comprising: A substrate having a first surface and a second surface opposite to the first surface; A first avalanche diode includes a first semiconductor region of a first conductivity type disposed in the substrate, wherein the majority carriers are charge carriers of the same conductivity type as the signal charge, and a fifth semiconductor region of a second conductivity type disposed between the first semiconductor region and the second surface, wherein the second conductivity type is different from the first conductivity type. as well as The second avalanche diode includes a second semiconductor region of the first conductivity type disposed in the substrate and a sixth semiconductor region of the second conductivity type disposed between the second semiconductor region and the second surface. The second avalanche diode is arranged adjacent to the first avalanche diode. A third avalanche diode includes an eighth semiconductor region of the first conductivity type disposed in the substrate, the third avalanche diode being arranged adjacent to the second avalanche diode, wherein... In the top view, the first avalanche diode and the second avalanche diode are aligned in a first direction, and the second avalanche diode and the third avalanche diode are aligned in a second direction orthogonal to the first direction. The first isolation portion is disposed at the first depth between the first semiconductor region and the second semiconductor region. At least one of the intrinsic semiconductor region, the third semiconductor region of the first conductivity type, and the fourth semiconductor region of the second conductivity type is arranged in the first isolation portion. The seventh semiconductor region of the second conductivity type is disposed between the fifth semiconductor region and the sixth semiconductor region, and On the line passing through the first isolation portion and the seventh semiconductor region and perpendicular to the first surface, the potential height relative to the signal charge decreases from the seventh semiconductor region toward the first isolation portion, and the difference between the potential height relative to the signal charge in the first semiconductor region and the potential height relative to the signal charge in the fifth semiconductor region is greater than the difference between the potential height relative to the signal charge in the first isolation portion and the potential height relative to the signal charge in the seventh semiconductor region. In the top view, a contact plug that provides a potential to a node of the first avalanche diode is arranged between the first semiconductor region and the eighth semiconductor region.

17. The photoelectric conversion device according to claim 16, wherein, The first isolation portion includes the third semiconductor region.

18. The photoelectric conversion device according to claim 17, wherein, The third semiconductor region is in contact with the first semiconductor region and the second semiconductor region.

19. The photoelectric conversion device according to claim 17, wherein, The third semiconductor region is shared by the first avalanche diode and the second avalanche diode.

20. The photoelectric conversion device according to claim 17, wherein, The impurity concentration in the third semiconductor region is lower than that in the first semiconductor region.

21. The photoelectric conversion device according to claim 16, wherein, A memory or counter circuit configured to detect an avalanche current generated based on a signal from the first avalanche diode is disposed on a second substrate different from the said substrate, and The substrate and the second substrate are stacked.

22. The photoelectric conversion device according to claim 16, wherein, A trench isolation is formed between the first semiconductor region and the second semiconductor region.

23. The photoelectric conversion device according to claim 22, wherein, One end of the trench isolation is formed to be deeper than the first semiconductor region.

24. The photoelectric conversion device according to claim 16, wherein, The first avalanche diode, the second avalanche diode, and the third avalanche diode operate in Geiger mode.

25. The photoelectric conversion device according to claim 16, further comprising: Color filters, among which Light passing through the color filter is incident on the first avalanche diode and the second avalanche diode.

26. The photoelectric conversion device according to claim 17, wherein, The ninth semiconductor region of the second conductivity type is disposed between the first semiconductor region and the eighth semiconductor region. The fourth semiconductor region is disposed between the first semiconductor region and the second semiconductor region. The contact plug is connected to the ninth semiconductor region, and The impurity concentration in the fourth semiconductor region is lower than that in the ninth semiconductor region.

27. The photoelectric conversion device according to claim 26, wherein... The contact plug is formed on the first surface of the substrate, and Light is incident from the second side of the substrate opposite to the first side.

28. The photoelectric conversion device according to claim 27, wherein, The first distance between the first semiconductor region and the second semiconductor region is shorter than the second distance between the first semiconductor region and the eighth semiconductor region.

29. The photoelectric conversion device according to claim 28, wherein, The first distance is at least 1 / 8 times the second distance.

30. The photoelectric conversion device according to claim 26, further comprising: At least one of a memory, a time-to-digital converter, and a counter is arranged corresponding to and configured to detect the avalanche current generated by avalanche multiplication in the first avalanche diode, wherein... In the top view, the contact plug that provides potential to the node is not positioned between the first semiconductor region and the second semiconductor region. The contact plug and the ninth semiconductor region are shared by the first avalanche diode, the second avalanche diode, and the third avalanche diode.

31. The photoelectric conversion device according to claim 30, further comprising: The second contact plug provides a potential to the first semiconductor region, wherein the distance between the second contact plug and the contact plug, the distance between the third contact plug providing a potential to the second semiconductor region and the contact plug, and the distance between the fourth contact plug providing a potential to the eighth semiconductor region and the contact plug are all equal to each other.

32. A photoelectric conversion system, comprising: The photoelectric conversion device according to any one of claims 1 to 31; as well as A signal processing unit is configured to process the signal output by the photoelectric conversion device.

33. A movable object comprising: The photoelectric conversion device according to any one of claims 1 to 31; as well as A distance information acquisition component is configured to obtain distance information about the distance to an object from ranging information based on signals from the photoelectric conversion device, wherein... The movable object also includes a control component configured to control the movable object based on the distance information.

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