Photoelectric converters, photoelectric converter systems, and equipment

Abstract

In high-resolution photoelectric converters, the goal is to suppress DCR and sensitivity degradation while maintaining pixel separation performance. [Solution] The device comprises a connection portion that electrically connects a contact plug of the anode wiring to a second semiconductor region of the second conductivity type. The connection portion has a third semiconductor region of the second conductivity type that is connected to the contact plug, and a fourth semiconductor region of the second conductivity type that is positioned between the third semiconductor region and the second semiconductor region. The impurity concentration of the third semiconductor region is higher than that of the second semiconductor region, and the impurity concentration of the fourth semiconductor region is lower than that of the third semiconductor region. With respect to the direction in which the APDs are aligned, the width of the separation portion is smaller than the width of the connection portion.

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion device, a photoelectric conversion system, and a device including the same.

Background Art

[0002] An avalanche photodiode (APD) that can detect weak light at the single photon level by utilizing avalanche (electron avalanche) multiplication is known as a photoelectric conversion device. In an APD, a P-type semiconductor region and an N-type semiconductor region are joined to form a high electric field region (avalanche multiplication section).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 discloses an APD in which a separation structure made of a silicon oxide film is arranged so as to surround an avalanche multiplication section. Such a separation structure can be expected to be effective in reducing crosstalk between adjacent pixels.

[0005] However, when the separation structure and the avalanche multiplication section are close to each other due to miniaturization of the pixel size, the dark count rate (DCR) may increase when a local high electric field acts between the two. In addition, since the separation structure itself is an insensitive region (that is, charges generated within the separation structure do not gather at the avalanche multiplication section and are not detected), there is also a problem that as the area occupied by the separation structure becomes larger compared to the APD, the sensitivity decreases. However, if the separation structure is made unnecessarily thin (thin), another problem may occur in that the electrical connection between the separation structure and the anode deteriorates.

[0006] Therefore, in high-resolution photoelectric converters, the challenge has been to suppress DCR and sensitivity degradation while maintaining inter-pixel separation performance. [Means for solving the problem]

[0007] This disclosure is, A first avalanche photodiode and a second avalanche photodiode each have a first semiconductor region of a first conductivity type in which the majority carriers are of the same conductivity type as the signal charge, An isolation portion disposed between the first avalanche photodiode and the second avalanche photodiode, the isolation portion including a second semiconductor region of a second conductivity type which is a different conductivity type from the first conductivity type, It includes a connection part that electrically connects the contact plug of the anode wiring and the second semiconductor region of the separation part, The aforementioned connection part is The third semiconductor region of the second conductivity type is connected to the contact plug of the anode wiring, The present invention comprises a fourth semiconductor region of the second conductivity type, which is disposed between the third semiconductor region and the second semiconductor region. The impurity concentration in the third semiconductor region is higher than that in the second semiconductor region. The impurity concentration in the fourth semiconductor region is lower than the impurity concentration in the third semiconductor region. The photoelectric conversion device includes a first direction in which the first avalanche photodiode and the second avalanche photodiode are aligned, wherein the width of the separation portion is smaller than the width of the connection portion.

[0008] This disclosure is, A first avalanche photodiode and a second avalanche photodiode each have a first semiconductor region of a first conductivity type in which the majority carriers are of the same conductivity type as the signal charge, An isolation portion disposed between the first avalanche photodiode and the second avalanche photodiode, the isolation portion including a second semiconductor region of a second conductivity type which is a different conductivity type from the first conductivity type, A second conductive type connector electrically connects the contact plug of the anode wiring and the second semiconductor region of the separation part, A fifth semiconductor region of second conductivity type, which is positioned on the light incidence side of the first semiconductor region, A sixth semiconductor region comprising either a semiconductor region of a first conductivity type having an impurity concentration lower than that of the first semiconductor region, or a semiconductor region of a second conductivity type having an impurity concentration lower than that of the fifth semiconductor region, The first semiconductor region and the fifth semiconductor region form an avalanche multiplication region. With respect to the first direction in which the first avalanche photodiode and the second avalanche photodiode are aligned, the width of the separation portion is smaller than the width of the connection portion. The sixth semiconductor region is also located between the connection portion and the fifth semiconductor region. Includes a photoelectric converter.

[0009] This disclosure includes photoelectric conversion systems and equipment comprising the aforementioned photoelectric conversion device. [Effects of the Invention]

[0010] According to the present invention, in a high-resolution photoelectric conversion device, it is possible to suppress DCR and sensitivity degradation while maintaining the separation performance between pixels. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of a photoelectric converter. [Figure 2] This is a schematic diagram of the sensor board of a photoelectric converter. [Figure 3] This is a schematic diagram of the circuit board of a photoelectric converter. [Figure 4]It is a configuration example of a pixel circuit of a photoelectric conversion device. [Figure 5] It is a schematic diagram showing the driving of a pixel circuit of a photoelectric conversion device. [Figure 6] It is a plan view of a photoelectric conversion device according to Example 1. [Figure 7] It is a cross-sectional view in the diagonal direction of a photoelectric conversion device according to Example 1. [Figure 8] It is a cross-sectional view in the opposite side direction of a photoelectric conversion device according to Example 1. [Figure 9] It is an enlarged view of the main part of a photoelectric conversion device according to Example 1. [Figure 10] It is a plan view of a photoelectric conversion device according to Example 2. [Figure 11] It is a cross-sectional view in the diagonal direction of a photoelectric conversion device according to Example 2. [Figure 12] It is a cross-sectional view in the opposite side direction of a photoelectric conversion device according to Example 2. [Figure 13] It is a plan view of a photoelectric conversion device according to Example 3. [Figure 14] It is a plan view of a photoelectric conversion device according to Example 4. [Figure 15] It is a cross-sectional view in the diagonal direction of a photoelectric conversion device according to Example 4. [Figure 16] It is a cross-sectional view in the diagonal direction and the opposite side direction of a photoelectric conversion device according to Example 5. [Figure 17] It is a plan view of a photoelectric conversion device according to Example 6. [Figure 18] It is a cross-sectional view in the diagonal direction of a photoelectric conversion device according to Example 6. [Figure 19] It is a cross-sectional view in the opposite side direction of a photoelectric conversion device according to Example 6. [Figure 20] It is a plan view of a photoelectric conversion device according to Example 7. [Figure 21] It is a cross-sectional view of a photoelectric conversion device according to Example 8. [Figure 22] It is a schematic diagram of a photoelectric conversion system according to Example 9. [Figure 23] It is a schematic diagram of a photoelectric conversion system according to Example 10. [Figure 24]This is a schematic diagram of the photoelectric conversion system according to Example 11. [Figure 25] This is a schematic diagram of the photoelectric conversion system according to Example 12. [Figure 26] This is a schematic diagram of the photoelectric conversion system according to Example 13. [Figure 27] This is a schematic diagram of the photoelectric conversion system according to Example 14. [Modes for carrying out the invention]

[0012] The embodiments shown below are intended to embody the technical concept of the present invention and do not limit it. The size and positional relationships of the components shown in each drawing may be exaggerated for clarity of explanation. In the following description, identical components may be given the same number and their explanation may be omitted.

[0013] Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "up," "down," "right," "left," and other terms including these terms) will be used as needed. The use of these terms is for the purpose of facilitating the understanding of embodiments with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention.

[0014] In this specification, a plan view refers to viewing a semiconductor layer from a direction perpendicular to the light incident surface. A cross-sectional view refers to a surface perpendicular to the light incident surface of the semiconductor layer. If the light incident surface of the semiconductor layer is rough when viewed microscopically, the plan view is defined based on the light incident surface of the semiconductor layer as viewed macroscopically.

[0015] A semiconductor layer has a first surface and a second surface opposite to the first surface, to which light is incident. In this specification, the depth direction is the direction from the first surface to the second surface of the semiconductor layer in which the APD is located. Hereafter, the "first surface" may be referred to as the "front surface" and the "second surface" may be referred to as the "back surface". The "depth" of a point or region within a semiconductor layer means the distance of that point or region from the first surface (front surface). There is a point (or region) Z1 whose distance (depth) from the first surface is d1 and a point (or region) Z2 whose distance (depth) from the first surface is d2, and when d1 > d2, it may be expressed as "Z1 is deeper than Z2" or "Z2 is shallower than Z1". Furthermore, if there is a point (or region) Z3 whose distance (depth) from the first surface is d3, and d1>d3>d2 holds, then this can be expressed as "Z3 is at a depth between Z1 and Z2" or "Z3 is between Z1 and Z2 with respect to the depth direction."

[0016] In the following description, the anode of the avalanche photodiode (APD) is set to a fixed potential, and the signal is taken from the cathode side. Therefore, the semiconductor region of the first conductivity type, which has majority carriers of the same polarity as the signal charge, is an N-type semiconductor region, and the semiconductor region of the second conductivity type, which has majority carriers of charges with a different polarity than the signal charge, is a P-type semiconductor region. Note that the present invention also applies when the cathode of the APD is set to a fixed potential and the signal is taken from the anode side. In this case, the semiconductor region of the first conductivity type, which has majority carriers of the same polarity as the signal charge, is a P-type semiconductor region, and the semiconductor region of the second conductivity type, which has majority carriers of charges with a different polarity than the signal charge, is an N-type semiconductor region. The following description will focus on the case where one node of the APD is set to a fixed potential, but the potentials of both nodes may fluctuate.

[0017] In this specification, when the term "impurity concentration" is used, it refers to the net impurity concentration after subtracting the amount compensated for by reverse-conducting impurities. "Concentration" refers to the NET doping concentration. The region where the concentration of P-type added impurities is higher than the concentration of N-type added impurities is the P-type semiconductor region. Conversely, the region where the concentration of N-type added impurities is higher than the concentration of P-type added impurities is the N-type semiconductor region.

[0018] First, the configuration common to each embodiment will be explained using Figures 1 to 5.

[0019] Figure 1 shows the configuration of a stacked photoelectric converter 100. The photoelectric converter 100 is constructed by stacking two members, a first member 11 and a second member 21, and electrically connecting them. The first member 11 has a first semiconductor layer having a photoelectric conversion element 102 (described later) and a first wiring structure. The second member 21 has a second semiconductor layer having a circuit such as a signal processing unit 103 (described later) and a second wiring structure. The photoelectric converter 100 is constructed by stacking the second semiconductor layer, the second wiring structure, the first wiring structure, and the first semiconductor layer in that order. The photoelectric converter 100 is a back-illuminated type photoelectric converter in which light is incident from the second surface and the second member 21 is located on the first surface side. The inventions according to each embodiment and example can also be applied to photoelectric converters having a front-illuminated structure, and can also be applied to photoelectric converters consisting of a single layer instead of a stacked type.

[0020] In the following description, the first member 11 and the second member 21 are explained as diced chips, but are not limited to chips. For example, each member may be a wafer. Also, each member may be stacked in a wafer state and then diced, or the first member chip and the second member chip may be joined together after being formed from a wafer state.

[0021] The first component 11 is provided with a pixel region 12 that has a sensor function. Therefore, the first component 11 may also be called a sensor component, sensor substrate, sensor chip, etc. The second component 21 is provided with a circuit region 22 that processes the signal detected in the pixel region 12. The second component 21 may also be called a circuit component, circuit substrate, circuit chip, etc.

[0022] Figure 2 shows an example of the arrangement of the first member 11. Pixels 101, each having a photoelectric conversion element 102 including an avalanche photodiode (APD), are arranged in a two-dimensional array in a planar view, forming a pixel region 12. Here, the left-right direction in Figure 2 is expressed as the "row direction," "horizontal direction," "x direction," etc., and the up-down direction in Figure 2 is expressed as the "column direction," "vertical direction," "y direction," etc. Also, the direction perpendicular to the plane of the paper in Figure 2 is expressed as the "depth direction," "z direction," etc.

[0023] Pixel 101 is typically a pixel used to form an image, but when used in TOF (Time of Flight), it does not necessarily have to form an image. In other words, pixel 101 may be used to measure the time and amount of light that arrives.

[0024] Figure 3 is a diagram showing the configuration of the second member 21. It includes a signal processing unit 103 for processing the charge photoelectrically converted by the photoelectric conversion element 102 in Figure 2, a readout circuit 112, a control pulse generation unit 115, a horizontal scanning circuit unit 111, a signal line 113, a vertical scanning circuit unit 110, and a drive line 116.

[0025] The photoelectric conversion element 102 in Figure 2 and the signal processing unit 103 in Figure 3 are electrically connected via connection wiring provided for each pixel.

[0026] The vertical scanning circuit section 110 receives control pulses supplied from the control pulse generation section 115 and supplies control pulses to each pixel via the drive line 116. Logic circuits such as a shift register and an address decoder are used in the vertical scanning circuit section 110.

[0027] The signal output from the photoelectric conversion element 102 of the pixel is processed by the signal processing unit 103. The number processing unit 103 is equipped with a counter and memory, and digital values ​​are stored in the memory.

[0028] The horizontal scanning circuit unit 111 inputs control pulses to the signal processing unit 103 to sequentially select each column in order to read the signal from the memory of each pixel in which the digital signal is held.

[0029] For the selected column, a signal is output from the signal processing unit 103 of the pixel selected by the vertical scanning circuit unit 110 to the signal line 113.

[0030] The signal output to signal line 113 is output via output circuit 114 to an external recording unit or signal processing unit of the photoelectric converter 100.

[0031] In Figure 2, the arrangement of photoelectric conversion elements in the pixel region may be one-dimensional. The function of the signal processing unit does not necessarily need to be provided for each photoelectric conversion element; for example, a single signal processing unit may be shared by multiple photoelectric conversion elements, and signal processing may be performed sequentially.

[0032] As shown in Figures 2 and 3, multiple signal processing units 103 are arranged in the region that overlaps with the pixel region 12 in a plan view. Then, the vertical scanning circuit unit 110, the horizontal scanning circuit unit 111, the readout circuit 112, the output circuit 114, and the control pulse generation unit 115 are arranged so as to overlap between the edge of the first member 11 and the edge of the pixel region 12 in a plan view. In other words, the first member 11 has a pixel region 12 and a non-pixel region arranged around the pixel region 12. Then, the vertical scanning circuit unit 110, the horizontal scanning circuit unit 111, the readout circuit 112, the output circuit 114, and the control pulse generation unit 115 are arranged in the region that overlaps with the non-pixel region in a plan view.

[0033] Figure 4 is an example of a block diagram including the equivalent circuits of Figures 2 and 3. In Figure 4, the photoelectric conversion element 102 having the APD201 is provided on the first member 11, and the other members are provided on the second member 21.

[0034] The APD201 generates charge pairs corresponding to incident light through photoelectric conversion. A voltage VL (first voltage) is supplied to the anode of the APD201. In addition, a voltage VH (second voltage), which is higher than the voltage VL supplied to the anode, is supplied to the cathode of the APD201. A reverse bias voltage is supplied to the anode and cathode such that the APD201 performs avalanche multiplication. By supplying these voltages, the charge generated by the incident light undergoes avalanche multiplication, and an avalanche current is generated.

[0035] Furthermore, when a reverse bias voltage is supplied, there are two modes of operation: Geiger mode, in which the potential difference between the anode and cathode is greater than the breakdown voltage, and linear mode, in which the potential difference between the anode and cathode is near or below the breakdown voltage.

[0036] An APD operating in Geiger mode is called a single-photon avalanche diode (SPAD). For example, the voltage VL (first voltage) is -30V and the voltage VH (second voltage) is 1V. The APD201 may operate in linear mode or Geiger mode. In the case of a SPAD, the potential difference is larger compared to a linear-mode APD, and the effect of voltage withstand capability is more pronounced, so it is preferable to use a SPAD.

[0037] The quench element 202 is connected to the power supply that provides voltage VH and to the APD201. The quench element 202 functions as a load circuit (quench circuit) when the signal is multiplied by avalanche multiplication, suppressing the voltage supplied to the APD201 and thereby suppressing avalanche multiplication (quench operation). In addition, the quench element 202 compensates for the voltage drop caused by the quench operation. By allowing current to flow, it functions to return the voltage supplied to the APD201 back to voltage VH (recharge operation).

[0038] The signal processing unit 103 includes a waveform shaping unit 210, a counter circuit 211, and a selection circuit 212. In this specification, the signal processing unit 103 may include any one of the waveform shaping unit 210, the counter circuit 211, or the selection circuit 212.

[0039] The waveform shaping unit 210 shapes the cathode potential change of the APD201 obtained during photon detection and outputs a pulse signal. For example, an inverter circuit can be used as the waveform shaping unit 210. Figure 4 shows an example in which one inverter is used as the waveform shaping unit 210, but a circuit in which multiple inverters are connected in series may be used, or other circuits that have a waveform shaping effect may be used.

[0040] The counter circuit 211 counts the pulse signal output from the waveform shaping unit 210 and holds the count value. When the control pulse pRES is supplied via the drive line 213, the signal held by the counter circuit 211 is reset.

[0041] The selection circuit 212 receives a control pulse pSEL from the vertical scanning circuit section 110 in Figure 3 via the drive line 214 in Figure 4, which switches the electrical connection between the counter circuit 211 and the signal line 113. The selection circuit 212 includes, for example, a buffer circuit for outputting a signal.

[0042] A switch such as a transistor may be placed between the quench element 202 and the APD201, or between the photoelectric conversion element 102 and the signal processing unit 103, to switch the electrical connection. Similarly, the supply of voltage VH or voltage VL to the photoelectric conversion element 102 may be electrically switched using a switch such as a transistor.

[0043] In this embodiment, a configuration using a counter circuit 211 is shown. However, instead of the counter circuit 211, a photoelectric converter 100 may be used that acquires pulse detection timing using a Time to Digital Converter (TDC) and memory. In this case, the generation timing of the pulse signal output from the waveform shaping unit 210 is converted into a digital signal by the TDC. A control pulse pREF (reference signal) is supplied to the TDC from the vertical scanning circuit unit 110 in Figure 3 via the drive line 213 to measure the timing of the pulse signal. The TDC acquires the signal as a digital signal when the input timing of the signal output from each pixel via the waveform shaping unit 210 is relative to the control pulse pREF.

[0044] Figures 5A and 5B schematically illustrate the relationship between the operation of the APD and the output signal. Figure 5A is an excerpt of the APD 201, quench element 202, and waveform shaping unit 210 from Figure 4. Here, the input side of the waveform shaping unit 210 is denoted as nodeA, and the output side as nodeB. The upper part of Figure 5B shows the waveform change at nodeA, and the lower part shows the waveform change at nodeB.

[0045] Between time t0 and time t1, a potential difference of VH-VL is applied to APD201. When a photon is incident on APD201 at time t1, avalanche multiplication occurs in APD201, an avalanche multiplication current flows through the quench element 202, and the voltage at nodeA drops. As the voltage drop increases further and the potential difference applied to APD201 decreases, the avalanche multiplication of APD201 stops as at time t2, and the voltage level at nodeA stops dropping below a certain value. Subsequently, between time t2 and time t3, a current flows through nodeA to compensate for the voltage drop from voltage VL, and at time t3, nodeA settles to its original potential level. At this time, the output waveform at nodeA exceeds a certain threshold. The remaining portion is waveform-shaped by the waveform shaping unit 210 and output as a signal at nodeB.

[0046] Note that the arrangement of the signal line 113, the read circuit 112, and the output circuit 114 is not limited to Figure 3. For example, the signal line 113 may be arranged extending in the row direction, and the read circuit 112 may be located at the end of the signal line 113.

[0047] The photoelectric conversion devices of each embodiment will be described below.

[0048] (Example 1) Figures 6, 7, and 8 show the structure of the first component 11 (sensor substrate) of the photoelectric conversion device according to Embodiment 1. Figure 6 is a plan view showing the configuration of the pixel region, schematically showing the semiconductor layer 300 of the first component 11 as viewed from the first surface side. Figure 7 is a cross-sectional view of Figure 6 along line AA (diagonal direction), and Figure 8 is a cross-sectional view of Figure 6 along line BB (opposite side direction).

[0049] As shown in Figure 6, multiple APD201s are arranged in a two-dimensional array in the semiconductor layer 300, in the row direction (left-right direction in Figure 6) and column direction (up-down direction in Figure 6). In Figure 6, for illustrative purposes, only nine APD201s in a 3x3 arrangement are depicted, but in actual products, for example, hundreds of thousands to millions of APD201s are formed. Each APD201 corresponds to one pixel.

[0050] The semiconductor layer 300 is provided with isolation sections 330, which are isolation structures for reducing crosstalk between adjacent APDs 201, 201. The isolation sections 330 are formed in a grid pattern by a plurality of row-direction isolation sections 330X extending in the row direction and a plurality of column-direction isolation sections 330Y extending in the column direction. An APD 201 is placed in each of the sections divided by this grid-like isolation section 330. In this embodiment, the section corresponding to one pixel has a substantially square shape in plan view. The boundaries of the sections are provided so as to overlap, for example, the isolation sections 330. The cathode wiring contact plugs 326 formed in the wiring structure 320 are placed substantially in the center of the pixel (section), and the anode wiring contact plugs 324 are placed at the four corners of the pixel. That is, in this embodiment, four anode contact plugs 324 are provided for one pixel.

[0051] As shown in Figures 7 and 8, the first component 11 (sensor substrate) has a structure in which a semiconductor layer 300 and a wiring structure 320 are stacked. The side of the semiconductor layer 300 facing the wiring structure 320 is called the first surface, and the side opposite the first surface is called the second surface. The semiconductor layer 300 is made of silicon, for example. On the second surface of the semiconductor layer 300, a fixed charge film 310, an insulating film 311, a planarization film 312, etc., are stacked in order, and a microlens 313 corresponding to each pixel is provided above them. In other words, the photoelectric conversion device of this embodiment has a so-called back-illuminated structure in which light is incident on the semiconductor layer 300 from the second surface side. The second surface is sometimes called the light incident surface. Furthermore, the following structure can be applied to the light incident surface. For example, at least one recess or protrusion, or other uneven structure, can be arranged on the second surface, which is the light incident surface. The uneven structure is made of silicon constituting the semiconductor layer 300 and other materials. For example, an insulator such as a silicon oxide film, a silicon oxynitride film, or a silicon nitride film is placed in a recess provided in the semiconductor layer 300. An interface with a refractive index difference that is not parallel to the second surface is formed. With this configuration, the incident light is diffracted, which can improve sensitivity to light in the infrared region.

[0052] The fixed charge film 310 is made of a dielectric material having a negative fixed charge and is arranged across the entire second surface of the semiconductor layer 300. The material of the fixed charge film 310 is selected from, for example, hafnium oxide, aluminum oxide, zirconium oxide, titanium oxide, tantalum oxide, and ruthenium oxide. However, aluminum oxide or hafnium oxide is preferred. The fixed charge film 310 may consist of multiple layers. The insulating film 311 is disposed on the fixed charge film 310, covering the entire second surface. The insulating film 311 can preferably be, for example, a silicon oxide film, a silicon oxynitride film, or a silicon nitride film. The insulating film 311 may consist of multiple layers. Although not shown in the figures, in addition to the planarization film 312, a filter layer such as a color filter or an infrared light cut filter may be provided on the second surface side of the semiconductor layer 300.

[0053] The wiring structure 320 is a structure in which multiple layers of wiring 321, 322, 323, via plugs 325, 327 for connecting the wirings, a contact plug 324 for the anode wiring, a contact plug 326 for the cathode wiring, etc. are arranged within the insulating layer 329. The lower surface of the wiring structure 320 (opposite the semiconductor layer 300) is the bonding surface with the second member 21, and multiple bonding portions 328 are provided on the bonding surface.

[0054] The semiconductor layer 300 has a first semiconductor region 301, a second semiconductor region 302, a third semiconductor region 303, a fourth semiconductor region 304, a fifth semiconductor region 305, a sixth semiconductor region 306, a seventh semiconductor region 307, an eighth semiconductor region 308, and a ninth semiconductor region 309. Each semiconductor region is a region to which impurities have been added by ion implantation, or a region to which impurities have been added during the fabrication and epitaxial growth of the semiconductor substrate. Here, the first semiconductor region 301, the sixth semiconductor region 306, the seventh semiconductor region 307, and the eighth semiconductor region 308 are semiconductor regions of the first conductivity type (N-type in this embodiment). The second semiconductor region 302, the third semiconductor region 303, the fourth semiconductor region 304, the fifth semiconductor region 305, and the ninth semiconductor region 309 are semiconductor regions of the second conductivity type (P-type in this embodiment).

[0055] The first semiconductor region 301 is a semiconductor region of the first conductivity type (N-type in this embodiment) and is provided on the first surface of the semiconductor layer 300. As shown in Figure 6, the first semiconductor region 301 in this embodiment is formed in a circular shape in the center of the pixel (partition) in a plan view. The cathode contact plug 326 is connected to the center of the first semiconductor region 301.

[0056] The fifth semiconductor region 305 is a semiconductor region of the second conductivity type (P-type in this embodiment) and is located on the light incident side (closer to the second surface) than the first semiconductor region 301. The fifth semiconductor region 305 is formed in layers to a predetermined depth so as to divide the epitaxial layer of the first conductivity type in one pixel (partition) into upper and lower halves. The periphery of the fifth semiconductor region 305 is in contact with the separation portion 330 surrounding the pixel. The epitaxial layer of the first conductivity type located on the first surface side of the fifth semiconductor region 305 is the sixth semiconductor region 306, and the epitaxial layer of the first conductivity type located on the second surface side is the eighth semiconductor region 308.

[0057] The first semiconductor region 301 of the first conductivity type and the fifth semiconductor region 305 of the second conductivity type form an avalanche multiplication region AM by a PN junction. The signal charge generated in the eighth semiconductor region 308 by photoelectric conversion is collected in the avalanche multiplication region AM. To improve the sensitivity of the APD201, it is preferable to increase the size of the eighth semiconductor region 308, which corresponds to the sensitivity region.

[0058] The seventh semiconductor region 307 is a first-conductivity semiconductor region formed around the first semiconductor region 301. The seventh semiconductor region 307 is also formed in a circular shape when viewed from above. Here, the impurity concentrations of the first semiconductor region 301, the seventh semiconductor region 307, and the sixth semiconductor region 306 are: Semiconductor Area 1 301 > Semiconductor Area 7 307 > Semiconductor Area 6 306 The following relationship is set to be satisfied: That is, the impurity concentration in the first semiconductor region 301 is At its highest, the impurity concentration in the seventh semiconductor region 307 is set to be between that of the first semiconductor region 307 and the sixth semiconductor region 306. This ensures an electrical connection between the cathode and the first semiconductor region 301 (i.e., APD201). In addition, the seventh semiconductor region 307 acts as a guard ring for electric field relaxation.

[0059] The ninth semiconductor region 309 is a second-conductivity type embedded layer provided across the entire second surface of the semiconductor layer 300. The ninth semiconductor region 309 plays a role in suppressing noise from the second surface side. Furthermore, a voltage VL from the anode wiring can be supplied to the ninth semiconductor region 309 via the second semiconductor region 302. In this case, a potential gradient for collecting charge can be formed.

[0060] In this embodiment, the separation section 330 is formed by a second semiconductor region 302 of the second conductivity type, and the potential barrier suppresses the movement of electrons between pixels. As shown in Figure 8, the second semiconductor region 302 is provided from a predetermined depth D1 to a position adjacent to the ninth semiconductor region 309 when considered in the depth direction from the first surface. By limiting the second semiconductor region 302 to the depth D1 and preventing it from being exposed to the first surface, it is possible to prevent charge (noise) generated near the first surface from traveling through the second conductivity type semiconductor region and entering the sensitivity region. Here, the depth D1 (the position of the first surface side edge of the second semiconductor region 302) is shallower than the fifth semiconductor region 305. In other words, the second semiconductor region 302 of the separation section 330 is preferably arranged to separate adjacent pixels with respect to at least the eighth semiconductor region 308, which is the sensitivity region, and the fifth semiconductor region 305, which forms the avalanche multiplication section AM. The second semiconductor region 302 can also be said to be located between at least several avalanche multiplication regions AM.

[0061] The first surface of the semiconductor layer 300 is provided with connection portions (303, 304) for electrically connecting the contact plug 324 of the anode wiring to the second semiconductor region 302 of the isolation portion 330. In this embodiment, the connection portion consists of a third semiconductor region 303 connected to the contact plug 324 and a fourth semiconductor region 304 positioned between the third semiconductor region 303 and the second semiconductor region 302. The second semiconductor region 302, the third semiconductor region 303, and the fourth semiconductor region 304 are all of the second conductivity type (P-type in this embodiment), and their impurity concentrations are as follows: Third Semiconductor Area 303 > Second Semiconductor Area 302 Third Semiconductor Area 303 > Fourth Semiconductor Area 304 The following relationship is satisfied: The impurity concentration in the third semiconductor region 303 is the highest. Specifically, the impurity concentration in the third semiconductor region 303 should be at least an order of magnitude higher than the impurity concentrations in the second semiconductor region 302 and the fourth semiconductor region 304. This enables a stable ohmic junction between the anode wiring contact plug 324 and the third semiconductor region 303. Furthermore, by lowering the impurity concentration in the fourth semiconductor region 304, a potential valley can be formed in the depth of the fourth semiconductor region 304, suppressing the entry of charge (noise) generated on the contact plug 324 into the sensitivity region (details will be described later).

[0062] The relationship between the impurity concentrations of the second semiconductor region 302 and the fourth semiconductor region 304 is arbitrary, but it is preferable to set the impurity concentration of the fourth semiconductor region 304 to the same value as or lower than the impurity concentration of the second semiconductor region 302. That is, Third semiconductor region 303 >> Second semiconductor region 302 ≥ Fourth semiconductor region 304 It is preferable that the following relationship is satisfied. For example, the impurity concentration in the third semiconductor region 303 is 1.0E 19 [atms / cm] 3 The order of magnitude is 1.0E17~1.0E18 [atms / cm²], and the impurity concentrations in the second semiconductor region 302 and the fourth semiconductor region 304 are 1.0E17~1.0E18 [atms / cm²]. 3 It is best to set the order to ].

[0063] As shown in Figure 6, the connection portions (303, 304) are positioned at locations corresponding to the intersection of the row-direction separation portion 330X and the column-direction separation portion 330Y. In areas other than the connection portion (third semiconductor region 303), the second conductivity type semiconductor region is not exposed on the first surface.

[0064] The anode wiring contact plugs 324 are positioned at the four corners of a single pixel area in a plan view, at a predetermined distance from the intersection of the separation section 330. The third semiconductor region 303 has a footprint slightly larger than the circumscribing rectangle of the four contact plugs 324 in order to make physical and electrical connections with the four contact plugs 324 arranged around one intersection. The footprint shape (planar shape when projected onto the first surface) of the third semiconductor region 303 in this embodiment is approximately square.

[0065] In the plan view of Figure 6, the two APD201s aligned diagonally (first direction) are symmetrically positioned with the intersection of the separation portion 330 and the third semiconductor region 303 in between. As shown in Figures 6 and 7, the sizes of the separation portion 330 and the third semiconductor region 303 are set such that, when comparing their widths in this first direction, the width W1 of the separation portion 330 (intersection) is smaller than the width W2 of the third semiconductor region 303 (connection portion).

[0066] With this configuration, the width of the separation section 330 in plan view can be made as small as possible, so even when the pixel size is miniaturized, sufficient distance can be secured between the separation section 330 and the avalanche multiplication section AM. Therefore, it is possible to achieve both pixel miniaturization (high resolution) and DCR suppression while maintaining the separation performance between pixels. In addition, by reducing the width of the separation section 330, which is a dead region, the size of the sensitive region can be relatively increased, and the aperture ratio of the pixels can be increased. Therefore, it is also possible to improve the sensitivity of the photoelectric converter. On the other hand, the third semiconductor region 303 for connecting the separation section 330 and the anode wiring is formed to be wider than the separation section 330, and the impurity concentration is higher than that of the second semiconductor region 302 of the separation section 330. Therefore, it is possible to achieve a stable ohmic junction with the anode wiring.

[0067] Furthermore, the fourth semiconductor region 304 has the same footprint as the third semiconductor region 303, and the width of the fourth semiconductor region 304 in the first direction is also the same as the width of the third semiconductor region 303, W2. Making the footprint shapes identical in this way has the advantage of simplifying manufacturing, as the third semiconductor region 303 and the fourth semiconductor region 304 can be manufactured using the same mask during the manufacturing of the semiconductor layer 300. However, it is not essential to make the footprint shapes and widths of the third semiconductor region 303 and the fourth semiconductor region 304 identical; the footprint and width of the fourth semiconductor region 304 may be smaller than those of the third semiconductor region 303. For example, the footprint and width of the fourth semiconductor region 304 may be made to match those of the intersection of the separation portion 330.

[0068] Figure 9 is an enlarged view of the main part of Figure 7, schematically showing the layer structure and potential of the semiconductor region directly above the contact plug 324 of the anode wiring. Directly above the contact plug 324 (dotted line in Figure 9), the third semiconductor region 303, the fourth semiconductor region 304, the sixth semiconductor region 306, and the fifth semiconductor region 305 are arranged in order from the first surface. Here, the third semiconductor region 303, the fourth semiconductor region 304, and the fifth semiconductor region 305 are of the second conductivity type (P-type in this embodiment), and the sixth semiconductor region 306 sandwiched between them is of the first conductivity type (N-type in this embodiment). Furthermore, when comparing the third semiconductor region 303 and the fourth semiconductor region 304, the impurity concentration of the fourth semiconductor region 304 is more than an order of magnitude lower. Therefore, In the region directly above the contact plug 324, a potential valley is formed at the depth of the sixth semiconductor region 306.

[0069] With this configuration, even if a charge 370 is generated at the junction with the contact plug 324, that charge 370 cannot cross the potential trough and is collected at the cathode as shown by the dotted arrow in Figure 9. Therefore, it is possible to suppress the entry of charge (noise) generated at the anode junction into the sensitive region, the eighth semiconductor region 308.

[0070] By adopting the structure of this embodiment described above, it becomes possible to provide a high-definition and high-performance photoelectric conversion device.

[0071] In the above embodiment, the sixth semiconductor region 306 is formed by a semiconductor region of a first conductivity type having an impurity concentration lower than that of the first semiconductor region 301, but the configuration of the sixth semiconductor region 306 is not limited to this. For example, the sixth semiconductor region 306 may be formed by a semiconductor region of a second conductivity type having an impurity concentration lower than that of the fifth semiconductor region 305. In this case, the carrier concentrations constituting the first conductivity types of the first semiconductor region 301, the seventh semiconductor region 307, and the sixth semiconductor region 306 are: Semiconductor Area 1 301 > Semiconductor Area 7 307 > Semiconductor Area 6 306 The following relationship is satisfied. Also, for example, the sixth semiconductor region 306 may be a neutral region. Similarly, the eighth semiconductor region 308 may be formed by a second conductivity type semiconductor region having a lower impurity concentration than the fifth semiconductor region 305, or it may be a neutral region. Also, when the eighth semiconductor region 308 and the sixth semiconductor region 306 are of the first conductivity type, the impurity concentrations of the eighth semiconductor region 308 and the sixth semiconductor region 306 are, Semiconductor Area 8 (308) > Semiconductor Area 6 (306) It may be set to satisfy the following relationship:

[0072] (Example 2) Figures 10, 11, and 12 show the structure of the first component 11 (sensor substrate) of the photoelectric conversion device according to Embodiment 2. Figure 10 is a plan view showing the configuration of the pixel region, schematically showing the semiconductor layer 300 of the first component 11 as viewed from the first surface side. Figure 11 is a cross-sectional view along line AA (diagonal direction) of Figure 10, and Figure 12 is a cross-sectional view along line BB (opposite side direction) of Figure 10. The same reference numerals are used for parts corresponding to Embodiment 1. The following describes the configuration that differs from Embodiment 1.

[0073] The isolation section 330 of this embodiment is composed of a DTI (Deep Trench Isolation) 331 which is an insulator, and a second semiconductor region 302 which is disposed between the DTI 331 and the APD 201. The DTI 331 of this embodiment is composed of an insulating film 311 and a fixed charge film 310 which is disposed between the insulating film 311 and the second semiconductor region 302 of the second conductivity type. The insulating film 311 is preferably, for example, a silicon oxide film, a silicon oxynitride film, or a silicon nitride film, and the fixed charge film 310 is preferably, for example, an aluminum oxide film or a hafnium oxide film. For example, the DTI 331 is manufactured by forming a trench that penetrates from the second surface to the first surface of the semiconductor layer 300, covering the inner wall of the trench with the fixed charge film 310, and embedding the insulating film 311.

[0074] This configuration can also produce the same effects as in Example 1. In addition, D The inclusion of TI331 is expected to further improve pixel separation performance and suppress crosstalk. The fixed charge film 310 forms a hole accumulation region, further enhancing the DCR and crosstalk suppression effects.

[0075] Furthermore, in the separation section 330 of this embodiment, as shown in Figure 12, the second semiconductor region 302 is provided from a predetermined depth D1 to a position where it contacts the ninth semiconductor region 309 when considered in the depth direction from the first surface. That is, the second semiconductor region 302 of the second conductivity type does not reach the first surface. Therefore, in areas where there are no connection sections (303, 304), the end of the DTI 331 on the first surface side is not covered by the semiconductor region of the second conductivity type and is in contact with the sixth semiconductor region 306. This structure prevents charge (noise) generated near the first surface from traveling through the semiconductor region of the second conductivity type and entering the sensitivity region. Here, the depth D1 (the position of the end of the second semiconductor region 302 on the first surface side) is shallower than the fifth semiconductor region 305.

[0076] In this embodiment, the DTI 331 penetrates to the first surface, but it is also acceptable to have a structure in which the DTI 331 is formed to a certain depth in the semiconductor layer 300. For example, the depth of the DTI 331 and the second semiconductor region 302 may be the same, and the bottom of the DTI 331 may be in contact with the connection portion (303, 304). Alternatively, a conductor may be embedded inside the DTI 331.

[0077] (Example 3) Figure 13 schematically shows the semiconductor layer 300 of the photoelectric converter according to Embodiment 3 as viewed from the first surface. The same reference numerals are used for parts corresponding to those in the above-described embodiment. The following describes a configuration that differs from the above-described embodiment.

[0078] In Examples 1 and 2, connection points were formed at four intersections corresponding to the four corners of each APD section (i.e., all intersections of the grid-like separation section 330). In contrast, in Example 3, the contact plugs 324 and connection points of the anode wiring are reduced. Specifically, contact plugs 324 and connection points (third semiconductor region 303, fourth semiconductor region 304) are placed only at two intersections corresponding to the diagonal corners of each APD section.

[0079] This configuration can also produce the same effects as the embodiments described above. In addition, by reducing the contact area with the anode, which can be a source of noise, it is possible to further reduce the DCR.

[0080] Furthermore, in this embodiment, the contact plugs 324 are thinned out so that the arrangement of contact plugs 324 is mirror symmetrical with respect to the row-direction separation section 330X, and the arrangement of contact plugs 324 is mirror symmetrical with respect to the column-direction separation section 330Y. As a result, four contact plugs 324 are clustered around one intersection, making the footprint area of ​​the connection section equivalent to that of embodiments 1 and 2. Therefore, stable ohmic bonding with the anode can be achieved. In addition, while a smaller footprint of the connection section can make it difficult to form a mask (resist), potentially leading to a decrease in manufacturing yield, this thinning method does not cause such problems. Therefore, the configuration of this embodiment is advantageous for pixel miniaturization.

[0081] (Example 4) Figures 14 and 15 show the structure of the first component 11 (sensor substrate) of the photoelectric conversion device according to Embodiment 4. Figure 14 is a plan view showing the configuration of the pixel region, schematically showing the semiconductor layer 300 of the first component 11 as viewed from the first surface side. Figure 15 is a cross-sectional view along line AA (diagonal direction) of Figure 14. The same reference numerals are used for parts corresponding to the embodiments described above. The following describes a configuration that differs from the embodiments described above.

[0082] In this embodiment, the contact plugs 324 and connection parts of the anode wiring are further reduced. Specifically, the contact plugs 324 and connection parts (third semiconductor region 303, fourth semiconductor region 304) are placed only at positions corresponding to the four corners of a unit consisting of four APD sections arranged in a 2x2 grid.

[0083] This configuration can also produce the same effects as the embodiments described above. In addition, by further reducing the contact area with the anode, which can be a source of noise, it is possible to further reduce the DCR.

[0084] Furthermore, in this embodiment, the contact plugs 324 are thinned out so that the arrangement of contact plugs 324 is mirror symmetrical with respect to the row-direction separation section 330X, and the arrangement of contact plugs 324 is mirror symmetrical with respect to the column-direction separation section 330Y. As a result, four contact plugs 324 are clustered around one intersection, making the footprint area of ​​the connection section equivalent to that of embodiments 1 and 2. Therefore, stable ohmic bonding with the anode can be achieved. In addition, while a smaller footprint of the connection section can make it difficult to form a mask (resist), potentially leading to a decrease in manufacturing yield, this thinning method does not cause such problems. Therefore, the configuration of this embodiment is advantageous for pixel miniaturization.

[0085] In this embodiment, the contact plug 324 and connection part are located in only one corner of the pixel section. Therefore, if the avalanche multiplication section AM is placed approximately in the center of the section, as in the embodiment described above, an asymmetric electric field will act on the avalanche multiplication section AM, which is undesirable. Therefore, it is preferable to position the first semiconductor region 301 and the seventh semiconductor region 307 of each of the four 2x2 sections at a position shifted toward the center of the unit consisting of these four sections. For example, as shown in Figure 14, it is preferable to position the first semiconductor region 301 at a position where the distance L2 between the connection part (303) and the first semiconductor region 301 is approximately equal to the distance L1 between the separation parts 330X, 330Y located toward the center of the unit and the first semiconductor region 301. This arrangement reduces the possibility of a localized high electric field acting on the first semiconductor region 301.

[0086] (Example 5) Figures 16A and 16B show the structure of the first component 11 (sensor substrate) of the photoelectric conversion device according to Embodiment 5. Figure 16A is a diagonal cross-sectional view of the semiconductor layer 300, and Figure 16B is a cross-sectional view of the semiconductor layer 300 in the opposite side direction. The same reference numerals are used for parts corresponding to the embodiments described above. The following describes a configuration that differs from the embodiments described above.

[0087] In this embodiment, the second conductivity type connection portion for electrically connecting the contact plug 324 of the anode wiring and the second semiconductor region 302 of the separation portion 330 is formed only of the third semiconductor region 303, which is different from the embodiment described above. The relative sizes of each semiconductor region and the relative impurity concentrations can be set in the same way as in the embodiment described above. This configuration can also produce the same effects as the embodiment described above.

[0088] Furthermore, as can be seen by comparing Figure 16A and Figure 16B, in this embodiment, the depth D1 of the second semiconductor region 302 at locations other than where the third semiconductor region 303, which is a connection, is located is greater than the depth D2 of the second semiconductor region 302 at locations other than where the connection is located. With this structure, in areas where no connection is located, it is possible to prevent charge (noise) generated near the first surface from traveling through the second conductivity type semiconductor region and entering the sensitivity region.

[0089] (Example 6) Figures 17, 18, and 19 show the structure of the first component 11 (sensor substrate) of the photoelectric conversion device according to Embodiment 6. Figure 17 is a plan view showing the configuration of the pixel region, schematically showing the semiconductor layer 300 of the first component 11 as viewed from the first surface side. Figure 18 is a cross-sectional view along line AA (diagonal direction) of Figure 17, and Figure 19 is a cross-sectional view along line BB (opposite side direction) of Figure 17. The same reference numerals are used for parts corresponding to the embodiments described above. The following describes a configuration that differs from the embodiments described above.

[0090] In this embodiment, an avalanche multiplication region AM is formed by a first semiconductor region 341 of a first conductivity type arranged on the first surface and a fifth semiconductor region 345 of a second conductivity type arranged on the second surface side of the first semiconductor region 341. A seventh semiconductor region 347 of a first conductivity type, which acts as a guard ring, is formed in a ring shape so as to cover the peripheral edge of the substantially circular first semiconductor region 341.

[0091] A semiconductor region 344 of the second conductivity type is positioned on the second surface side of the fifth semiconductor region 345, and a ninth semiconductor region 309 of the second conductivity type is positioned on the second surface side of semiconductor region 344. In this case, it is preferable that the impurity concentration of the ninth semiconductor region 309 be higher than that of semiconductor region 344. With such a setting, the charge photoelectrically converted in the sensitive semiconductor region 344 is collected in the avalanche multiplier AM located on the first surface side without passing through to the second surface side. Therefore, it becomes possible to efficiently read out the signal charge.

[0092] In the APD201 of this embodiment, by applying a separation section 330 and a connection section with the same structure as in the above-described embodiment, the same effects and advantages as in the above-described embodiment can be achieved.

[0093] (Example 7) Refer to Figures 20A to 20C to explain the variations in the footprint shape of the connection part.

[0094] Figure 20A shows an example where a roughly square-shaped third semiconductor region 303 is arranged so that the four corners of the square align with the positions of the four contact plugs 324. Figure 20B shows an example where a roughly square-shaped third semiconductor region 303 is arranged so that the diagonal of the square overlaps with the separation portion 330. Figure 20C shows an example where a connection portion is formed by a roughly circular-shaped third semiconductor region 303.

[0095] To ensure an electrical connection with the anode, the required size (width) of the third semiconductor region 303 is predetermined. For example, assuming the arrangement of the contact plugs 324 in Figures 20A to 20C is the same, the diagonal width of the third semiconductor region 303 must be at least W in each shape. Comparing the area of ​​the third semiconductor region 303 in each shape, the area of ​​the shape in Figure 20A is W 2 / 2, the area of ​​the shape in Figure 20B is W 2 The area of ​​the shape in Figure 20C is πW. 2The result is / 4, indicating that the shape of Figure 20A is suitable for the minimum area. The third semiconductor region 303 is a source of dark current, so a smaller area is preferable. Therefore, from the viewpoint of minimizing area, the shape of Figure 20A is preferable.

[0096] On the other hand, the shapes in Figures 20B and 20C have the advantage that there are no corners within the pixel compartment (aperture). For example, if there is a corner 350 as in the shape of Figure 20A, a localized high electric field may act on that corner 350. From the standpoint of making it less likely for such electric field concentration to occur, the shapes in Figures 20B and 20C, which do not have corners, are preferable.

[0097] Note that the shapes shown in Figures 20A to 20C are merely examples, and the shape of the connection portion (third semiconductor region 303) is not limited to these.

[0098] (Example 8) Figure 21 is a cross-sectional view showing an example configuration of a stacked photoelectric converter 100.

[0099] The first component 11 (sensor substrate) has a first semiconductor layer 300 and a first wiring structure 320. The first semiconductor layer 300 has the APD201, separation portion 330, connection portion (303, 304), etc., as described in each of the above embodiments. The first component 11 has an opening 360 that extends from the first surface (light incident surface) to the middle of the first wiring structure 320, and a pad 361 is exposed at the bottom of the opening 360. This pad 361 is an aluminum electrode used for connection to an external device, and for example, a bonding wire (not shown) is installed thereon.

[0100] The second component 21 (circuit board) has a second semiconductor layer 420 and a second wiring structure 410. A signal processing unit 402 having multiple semiconductor elements is formed on the second semiconductor layer 420. In addition, wiring 401 related to the signal processing unit 402 is formed on the second wiring structure 410.

[0101] The photoelectric converter 100 is fabricated by stacking the first member 11 and the second member 21 such that their respective wiring structures 320 and 410 face each other. The electrical connection between the first member 11 and the second member 21 is made via the joint 328.

[0102] (Example 9) The photoelectric conversion system according to Example 9 will be explained with reference to Figure 22. Figure 22 is a block diagram showing the schematic configuration of the photoelectric conversion system related to Example 9.

[0103] The photoelectric conversion devices described in Examples 1 to 8 above are applicable to various photoelectric conversion systems. A photoelectric conversion system comprises at least the photoelectric conversion device according to the above examples and a signal processing unit that processes the signals output from the photoelectric conversion device. Examples of devices to which such a photoelectric conversion system can be applied include digital still cameras, digital camcorders, surveillance cameras, photocopiers, fax machines, mobile phones, in-vehicle cameras, observation satellites, sensors, and measuring instruments. Camera modules, which include optical systems such as lenses and imaging devices, are also included in devices to which a photoelectric conversion system is applied. Figure 22 shows a block diagram of a digital still camera as an example of these.

[0104] Figure 22 shows an example of the configuration of an imaging system SYS constructed using an imaging device IS. The imaging system SYS is an information terminal with a camera and imaging functions. The imaging device IS may further include a package PKG that houses the imaging device IC. The package PKG may include a base on which the imaging device IC is fixed, a cover facing the imaging device IC, and connecting members that connect terminals provided on the base and terminals provided on the imaging device IC. The imaging device IS can also mount multiple imaging device ICs side by side in a common package PKG. Furthermore, the imaging device IS can also mount imaging device ICs and other semiconductor device ICs on top of each other in a common package PKG.

[0105] The imaging system SYS may include an optical system OU that forms an image on the imaging device IS. The imaging system SYS may also include at least one of a control unit CU that controls the imaging device IS, a processing unit PU that processes signals obtained from the imaging device IS, a display device DU that displays the image obtained from the imaging device IS, and a storage device MU that stores the image obtained from the imaging device IS.

[0106] (Example 10) Figures 23A and 23B show the equipment to which the photoelectric conversion system of Example 10 is applied. Let me explain. Figures 23A and 23B show the configuration of the photoelectric conversion system and equipment in this embodiment.

[0107] Figure 23A shows an example of a photoelectric conversion system related to an in-vehicle camera. The photoelectric conversion system 2300 has an imaging device 2310. The imaging device 2310 is a photoelectric conversion device as described in any of the embodiments above. The photoelectric conversion system 2300 has an image processing unit 2312 that performs image processing on a plurality of image data acquired by the imaging device 2310, and a parallax acquisition unit 2314 that calculates parallax (phase difference of parallax images) from a plurality of image data acquired by the photoelectric conversion system 2300. The photoelectric conversion system 2300 also has a distance measurement unit 2316 that calculates the distance to an object based on the calculated parallax, and a collision determination unit 2318 that determines whether or not there is a possibility of collision based on the calculated distance. Here, the parallax acquisition unit 2314 and the distance measurement unit 2316 are examples of distance information acquisition means that acquire distance information to an object. That is, distance information is information related to parallax, defocus amount, distance to an object, etc. The collision determination unit 2318 may use any of this distance information to determine the possibility of a collision. The means for acquiring distance information may be implemented by specially designed hardware or by a software module. It may also be implemented by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or a combination thereof.

[0108] The photoelectric conversion system 2300 is connected to the vehicle information acquisition device 2320 and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The photoelectric conversion system 2300 is also connected to the control ECU 2330, which is a control unit that outputs a control signal to generate braking force on the vehicle based on the judgment result of the collision judgment unit 2318. The photoelectric conversion system 2300 is also connected to the warning device 2340, which issues a warning to the driver based on the judgment result of the collision judgment unit 2318. For example, if the collision judgment result of the collision judgment unit 2318 indicates a high probability of collision, the control ECU 2330 performs vehicle control to avoid a collision or mitigate damage by applying the brakes, releasing the accelerator, or suppressing engine output. The warning device 2340 warns the user by sounding an alarm, displaying warning information on a screen such as a car navigation system, or vibrating the seat belt or steering wheel.

[0109] In this embodiment, the photoelectric conversion system 2300 images the area around the vehicle, for example, the front or rear. Figure 23B shows the photoelectric conversion system 2300 when imaging the area in front of the vehicle (imaging range 2350). The vehicle information acquisition device 2320 sends instructions to the photoelectric conversion system 2300 or the imaging device 2310. This configuration can further improve the accuracy of distance measurement.

[0110] The above example illustrates control to prevent collisions with other vehicles, but the photoelectric conversion system can also be applied to control systems that automatically follow other vehicles or automatically stay within their lanes. Furthermore, the photoelectric conversion system can be applied not only to vehicles such as the vehicle itself, but also to mobile objects (mobile devices) such as ships, aircraft, or industrial robots. In addition, it can be applied not only to mobile objects but also to a wide range of devices that utilize object recognition, such as intelligent transportation systems (ITS).

[0111] (Example 11) The equipment to which the photoelectric conversion system of Example 11 is applied will be described with reference to Figure 24. Figure 24 is a block diagram showing an example configuration of a distance image sensor, which is an example of equipment to which the photoelectric conversion system of this embodiment is applied.

[0112] As shown in Figure 24, the distance image sensor 1401 is connected to the optical system 1402 and the photoelectric converter 14 03. The system comprises an image processing circuit 1404, a monitor 1405, and a memory 1406. The distance image sensor 1401 receives light (modulated light or pulsed light) that is projected from the light source device 1411 toward the subject and reflected from the surface of the subject, thereby acquiring a distance image corresponding to the distance to the subject.

[0113] The optical system 1402 is composed of one or more lenses and guides the image light (incident light) from the subject to the photoelectric converter 1403, where it forms an image on the light-receiving surface (sensor part) of the photoelectric converter 1403.

[0114] The photoelectric converter 1403 is one of the photoelectric converters described in each of the above embodiments, and a distance signal indicating the distance obtained from the light received signal output from the photoelectric converter 1403 is supplied to the image processing circuit 1404.

[0115] The image processing circuit 1404 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric converter 1403. The distance image (image data) obtained through this image processing is then supplied to the monitor 1405 for display or supplied to the memory 1406 for storage (recording).

[0116] With the distance image sensor 1401 configured in this way, more accurate distance images can be acquired by applying the photoelectric conversion device described above.

[0117] (Example 12) The equipment to which the photoelectric conversion system of Example 12 is applied will be described with reference to Figure 25. Figure 25 is a diagram showing an example of a schematic configuration of an endoscopic surgical system, which is equipment to which the photoelectric conversion system of this embodiment is applied.

[0118] Figure 25 illustrates a surgeon (physician) 1131 performing surgery on a patient 1132 on a patient bed 1133 using an endoscopic surgical system 1003. As shown in the figure, the endoscopic surgical system 1003 consists of an endoscope 1100, surgical instruments 1110, and a cart 1134 equipped with various devices for endoscopic surgery.

[0119] The endoscope 1100 consists of a barrel 1101, the tip of which is inserted into the body cavity of the patient 1132 for a predetermined length, and a camera head 1102 connected to the base end of the barrel 1101. In the illustrated example, the endoscope 1100 is shown as a so-called rigid endoscope having a rigid barrel 1101, but the endoscope 1100 may also be configured as a so-called flexible endoscope having a flexible barrel.

[0120] An opening into which an objective lens is fitted is provided at the tip 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 to the tip of the endoscope tube by a light guide extending inside the endoscope tube 1101, and is irradiated through the objective lens towards the object to be observed inside the body cavity of the patient 1132. The endoscope 1100 may be a straight-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0121] The camera head 1102 contains an optical system and a photoelectric converter. Reflected light from the object being observed (observation light) is focused by the optical system into the photoelectric converter. The photoelectric converter converts the observation light into electrical signals, generating an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The photoelectric converter can be any of the photoelectric converters described in the embodiments described above. The image signal is transmitted as RAW data to the camera control unit (CCU) 1135.

[0122] The CCU1135 consists of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and other components, and comprehensively controls the operation of the endoscope 1100 and the display device 1136. Furthermore, the CCU1135 receives an image signal from the camera head 1102 and performs various image processing operations on that image signal, such as development processing (demosaic processing), to display the image based on that image signal.

[0123] The display device 1136 displays an image based on an image signal that has been processed by the CCU 1135, under control from the CCU 1135.

[0124] The light source device 1203 consists of a light source such as an LED (Light Emitting Diode) and supplies illumination light to the endoscope 1100 when photographing the surgical area, etc.

[0125] The input device 1137 is an input interface for the endoscopic surgical system 1003. The user can input various types of information and instructions to the endoscopic surgical system 1003 via the input device 1137.

[0126] The control device 1138 controls the drive of the energy treatment instrument 1112 for purposes such as tissue cauterization, incision, or blood vessel sealing.

[0127] The light source device 1203, which supplies illumination light to the endoscope 1100 when photographing the surgical area, can be composed of, for example, an LED, a laser light source, or a combination thereof. When the white light source is composed of a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so the white balance of the captured image can be adjusted in the light source device 1203. In this case, it is also possible to capture images corresponding to each of the RGB colors in time-division by irradiating the observation target with laser light from each of the RGB laser light sources in time-division and controlling the drive of the image sensor of the camera head 1102 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter on the image sensor.

[0128] Furthermore, the light source device 1203 may be controlled to change the intensity of the light it outputs at predetermined time intervals. By controlling the drive of the image sensor of the camera head 1102 in synchronization with the timing of the change in light intensity, images can be acquired in time-division order, and these images can be combined to generate high dynamic range images without so-called black crushing and white clipping.

[0129] Furthermore, the light source device 1203 may be configured to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, the wavelength dependence of light absorption in body tissue is utilized. Specifically, by irradiating with narrowband light compared to the irradiation light used during normal observation (i.e., white light), predetermined tissues such as blood vessels on the surface of mucosa can be imaged with high contrast. Alternatively, in special light observation, fluorescence observation may be performed to obtain an image from fluorescence generated by irradiation with excitation light. In fluorescence observation, excitation light can be irradiated onto body tissue and fluorescence from the body tissue can be observed, or a reagent such as indocyanine green (ICG) can be injected into body tissue and excitation light corresponding to the fluorescence wavelength of the reagent can be irradiated onto the body tissue to obtain a fluorescence image. The light source device 1203 may be configured to supply narrowband light and / or excitation light corresponding to such special light observation.

[0130] (Example 13) Figures 26A and 26B show the equipment to which the photoelectric conversion system related to Example 13 is applied. I will use it to explain.

[0131] Figure 26A shows eyeglasses 1600 (smart glasses), a device to which the photoelectric conversion system of this embodiment is applied. The eyeglasses 1600 have a photoelectric conversion device 1602. The photoelectric conversion device 1602 is the photoelectric conversion device described in each of the embodiments described above. In addition, a display device including a light-emitting device such as an OLED or LED may be provided on the back side of the lens 1601. There may be one or more photoelectric conversion devices 1602. In addition, multiple types of photoelectric conversion devices may be used in combination. The arrangement position of the photoelectric conversion device 1602 is not limited to that shown in Figure 26A.

[0132] The eyeglasses 1600 further include a control device 1603. The control device 1603 functions as a power supply that provides power to the photoelectric converter 1602 and the display device. The control device 1603 also controls the operation of the photoelectric converter 1602 and the display device. Furthermore, the control device 1603 functions as a signal processing unit that processes the signals output from the photoelectric converter 1602. The lens 1601 has an optical system formed therein for focusing light onto the photoelectric converter 1602.

[0133] Figure 26B shows eyeglasses 1610 (smart glasses), a device to which the photoelectric conversion system of this embodiment is applied. The arrangement of the photoelectric conversion system differs from that in Figure 26A. The eyeglasses 1610 have a control device 1612. The control device 1612 is equipped with a photoelectric conversion device corresponding to the photoelectric conversion device 1602 and a display device. The lens 1611 has an optical system formed therein for projecting light emitted from the photoelectric conversion device in the control device 1612 and from the display device, and an image is projected onto the lens 1611. The control device 1612 functions as a power supply that supplies power to the photoelectric conversion device and the display device, and also controls the operation of the photoelectric conversion device and the display device. The control device 1612 may have a gaze detection unit that detects the wearer's gaze. Gaze detection may use infrared light. The infrared light emitter emits infrared light towards the eyeball of the user who is fixating on the displayed image. An imaging unit having a light-receiving element detects the reflected light from the eyeball of the emitted infrared light, thereby obtaining an image of the eyeball. By having a reduction mechanism that reduces the amount of light transmitted from the infrared light-emitting part to the display part in a planar view, the degradation of image quality is reduced.

[0134] The user's gaze towards the displayed image is detected from an image of the eyeball obtained by imaging with infrared light. Any known method can be applied to gaze detection using an image of the eyeball. For example, a gaze detection method based on the Purkinje image obtained by the reflection of the irradiated light from the cornea can be used.

[0135] More specifically, gaze detection processing is performed based on the pupil-corneal reflection method. Using the pupil-corneal reflection method, a gaze vector representing the orientation (rotation angle) of the eyeball is calculated based on the pupil image and Purkinje image contained in the captured image of the eyeball, thereby detecting the user's gaze.

[0136] The display device of this embodiment includes a photoelectric converter having a light-receiving element, and may control the display image of the display device based on the user's gaze information from the photoelectric converter.

[0137] Specifically, the display device determines a first field of view that the user is fixated on, and a second field of view other than the first field of view, based on gaze information. The first and second field of view may be determined by the control device of the display device, or they may be determined by an external control device and received. Within the display area of ​​the display device, the display resolution of the first field of view may be controlled to be higher than that of the second field of view. In other words, the resolution of the second field of view may be lower than that of the first field of view.

[0138] Furthermore, the display area includes a first display area and a second display area different from the first display area, and based on line-of-sight information, the area with higher priority may be determined from the first display area and the second display area. The first and second field-of-sight areas may be determined by the control device of the display device. It is acceptable to receive a resolution determined by an external control device. The resolution of high-priority areas may be controlled to be higher than the resolution of areas other than high-priority areas. In other words, the resolution of areas with relatively low priority may be set lower.

[0139] AI may be used to determine the first field of view area and the areas with higher priority. The AI ​​may be a model configured to estimate the angle of gaze and the distance to the target object at the end of the line of sight from the image of the eye, using the image of the eye and the direction the eye was actually looking in that image as training data. The AI ​​program may be installed in the display device, the photoelectric converter, or an external device. If installed in an external device, it will be transmitted to the display device via communication.

[0140] When display control is based on visual detection, this method is preferably applicable to smart glasses that further include a photoelectric converter for capturing images of the surrounding environment. The smart glasses can display the captured external information in real time.

[0141] (Example 14) The photoelectric conversion device and photoelectric conversion system described above may be applied to electronic devices such as smartphones and tablets.

[0142] Figures 27A and 27B show an example of an electronic device 1500 equipped with a photoelectric converter. Figure 27A shows the front side of the electronic device 1500, and Figure 27B shows the back side of the electronic device 1500.

[0143] As shown in Figure 27A, a display 1510 for displaying images is positioned in the center of the surface of the electronic device 1500. Along the top edge of the surface of the electronic device 1500, front cameras 1521 and 1522 using photoelectric converters, an IR light source 1530 that emits infrared light, and a visible light source 1540 that emits visible light are positioned.

[0144] Furthermore, as shown in Figure 27B, rear cameras 1551 and 1552, which use photoelectric converters, an IR light source 1560 that emits infrared light, and a visible light source 1570 that emits visible light are arranged along the upper edge of the back of the electronic device 1500.

[0145] In the electronic device 1500 configured in this way, by applying the photoelectric converter described above, it is possible to capture, for example, higher-quality images. The photoelectric converter can also be applied to other electronic devices such as infrared sensors, distance measuring sensors using active infrared light sources, security cameras, and personal or biometric authentication cameras. This can improve the accuracy and performance of these electronic devices.

[0146] (others) Although various devices have been described in the above embodiments, further mechanical devices may be included. In a camera, the mechanical device can drive components of the optical system for zooming, focusing, and shutter operation. Alternatively, the mechanical device in a camera can move a photoelectric converter for vibration damping.

[0147] Furthermore, the equipment may be transportation equipment such as vehicles, ships, or aircraft. Mechanical devices in transportation equipment can be used as moving devices. Equipment as transportation equipment is suitable for transporting photoelectric converters or for assisting and / or automating driving (piloting) through imaging functions. Processing devices for assisting and / or automating driving (piloting) can perform processing to operate mechanical devices as moving devices based on information obtained from the photoelectric converter.

[0148] The present invention is not limited to the embodiments described above and can be modified in various ways. For example, examples in which a part of the configuration of one embodiment is added to another embodiment, or in which a part of the configuration of another embodiment is replaced, are also included as embodiments of the present invention. It should be noted that the above embodiments are merely examples of concrete implementations of the present invention, and the technical scope of the present invention should not be interpreted as being limited by them. In other words, the present invention can be implemented in various ways without departing from its technical concept or its main features. [Explanation of Symbols]

[0149] 100: Photoelectric converter 201: Avalanche photodiode 301: First Semiconductor Area 302: Second Semiconductor Area 303: Third Semiconductor Area 304: Fourth Semiconductor Area 324: Anode wiring contact plug 330: Separation part

Claims

1. A first avalanche photodiode and a second avalanche photodiode each have a first semiconductor region of a first conductivity type in which the majority carriers are of the same conductivity type as the signal charge, An isolation portion disposed between the first avalanche photodiode and the second avalanche photodiode, the isolation portion including a second semiconductor region of a second conductivity type which is a different conductivity type from the first conductivity type, It includes a connection part that electrically connects the contact plug of the anode wiring and the second semiconductor region of the separation part, The aforementioned connection part is The third semiconductor region of the second conductivity type is connected to the contact plug of the anode wiring, The present invention comprises a fourth semiconductor region of the second conductivity type, which is disposed between the third semiconductor region and the second semiconductor region. The impurity concentration in the third semiconductor region is higher than that in the second semiconductor region. The impurity concentration in the fourth semiconductor region is lower than the impurity concentration in the third semiconductor region. A photoelectric converter in which, with respect to a first direction in which the first avalanche photodiode and the second avalanche photodiode are aligned, the width of the separation portion is smaller than the width of the connection portion.

2. The impurity concentration in the aforementioned fourth semiconductor region is the same as or lower than the impurity concentration in the aforementioned second semiconductor region. The photoelectric conversion device according to claim 1.

3. The material further comprises a fifth semiconductor region of a second conductivity type, which is located on the light incidence side of the first semiconductor region. The first semiconductor region and the fifth semiconductor region form an avalanche multiplication region. The photoelectric conversion device according to claim 1 or 2.

4. The present invention further comprises a sixth semiconductor region disposed between the connection portion and the fifth semiconductor region, The sixth semiconductor region is either a semiconductor region of the first conductivity type having an impurity concentration lower than that of the first semiconductor region, or a semiconductor region of the second conductivity type having an impurity concentration lower than that of the fifth semiconductor region. The photoelectric conversion device according to claim 3.

5. The width of the third semiconductor region in the first direction and the width of the fourth semiconductor region in the first direction are the same. A photoelectric conversion device according to any one of claims 1 to 4.

6. A first avalanche photodiode and a second avalanche photodiode each have a first semiconductor region of a first conductivity type in which the majority carriers are of the same conductivity type as the signal charge, An isolation portion disposed between the first avalanche photodiode and the second avalanche photodiode, the isolation portion including a second semiconductor region of a second conductivity type which is a different conductivity type from the first conductivity type, A second conductive type connector electrically connects the contact plug of the anode wiring to the second semiconductor region of the separation part, A fifth semiconductor region of the second conductivity type, which is positioned on the light incidence side of the first semiconductor region, 、 A sixth semiconductor region comprising either a semiconductor region of a first conductivity type having an impurity concentration lower than that of the first semiconductor region, or a semiconductor region of a second conductivity type having an impurity concentration lower than that of the fifth semiconductor region, The first semiconductor region and the fifth semiconductor region form an avalanche multiplication region. With respect to the first direction in which the first avalanche photodiode and the second avalanche photodiode are aligned, the width of the separation portion is smaller than the width of the connection portion. The sixth semiconductor region is also located between the connection portion and the fifth semiconductor region. Photoelectric converter.

7. The aforementioned connection portion is arranged on the first surface of the semiconductor layer. The second semiconductor region is positioned deeper than the connection portion within the semiconductor layer when viewed from the first surface. The depth of the second semiconductor region at the location where the connection portion is located is different from the depth of the second semiconductor region at other locations. The photoelectric conversion device according to claim 6.

8. The depth of the second semiconductor region at a location other than the depth of the second semiconductor region at the location where the connection portion is located is greater. The photoelectric conversion device according to claim 7.

9. The separation unit further includes an insulator that separates the first avalanche photodiode and the second avalanche photodiode. The second semiconductor region is located between the insulator and each avalanche photodiode. A photoelectric conversion device according to any one of claims 1 to 8.

10. The insulator has a fixed charge film disposed between the second semiconductor regions. The photoelectric conversion device according to claim 9.

11. The insulator has a portion that is not covered by the semiconductor region of the second conductivity type. The photoelectric conversion device according to claim 9 or 10.

12. The separation section is formed in a grid pattern by a plurality of row-direction separation sections extending in the row direction and a plurality of column-direction separation sections extending in the column direction. An avalanche photodiode is placed in each of the sections separated by the grid-like separation section, and the first avalanche photodiode and the second avalanche photodiode are avalanche photodiodes arranged diagonally across the section. The connecting portion is formed at the intersection of the row-direction separating portion and the column-direction separating portion. A photoelectric conversion device according to any one of claims 1 to 11.

13. The connection portion is formed at four intersections corresponding to the four corners of each avalanche photodiode section. The photoelectric conversion device according to claim 12.

14. The connection portion is formed at two intersections corresponding to the diagonal corners of each avalanche photodiode section. The photoelectric conversion device according to claim 12.

15. The connecting portion is formed at the four intersections corresponding to the four corners of a unit consisting of four sections arranged in two rows and two columns. The photoelectric conversion device according to claim 12.

16. The first semiconductor region of each of the four sections constituting the unit is positioned so as to be shifted toward the center of the unit. The photoelectric conversion device according to claim 15.

17. A photoelectric conversion device according to any one of claims 1 to 16, A signal processing unit that processes the signal output from the photoelectric converter, A photoelectric conversion system having

18. A photoelectric conversion device according to any one of claims 1 to 16, Optical system corresponding to the aforementioned photoelectric converter, A control device for controlling the aforementioned photoelectric converter, A processing device that processes the signal output from the aforementioned photoelectric converter, A display device that displays information obtained by the aforementioned photoelectric converter. A storage device for storing information obtained by the photoelectric converter, and At least one of the following: a mechanical device that operates based on information obtained from the aforementioned photoelectric converter, Equipment equipped with the following features.

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