Photoelectric conversion device, photoelectric conversion system, and equipment

Abstract

To reduce a DCR and prevent a reduction in sensitivity while maintaining separation performance between pixels in a high-definition photoelectric conversion device.SOLUTION: A photoelectric conversion device comprises a connection part that electrically connects a contact plug of anode wiring and a second semiconductor area of a second conductivity type. The connection part has a third semiconductor area of a second conductivity type connected with the contact plug, and a fourth semiconductor area of the second conductivity type arranged between the third semiconductor area and the second semiconductor area. The concentration of impurities in the third semiconductor area is higher than the concentration of impurities in the second semiconductor area, and the concentration of impurities in the fourth semiconductor area is lower than the concentration of impurities in the third semiconductor area. With respect to a direction in which APDs are arranged side by side, the width of a separation part is smaller than the width of the connection part.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] Avalanche photodiodes (APDs) are known photoelectric conversion devices that utilize avalanche multiplication to detect weak light at the single photon level. In APDs, a high-electric field region (avalanche multiplication section) is formed by joining a P-type semiconductor region and an N-type semiconductor region. [Prior art documents] [Patent documents]

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

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

[0005] However, as pixel size becomes smaller, the isolation structure and the avalanche multiplication section become closer, which can increase the dark count rate (DCR) when a local high electric field acts between them. Furthermore, because the isolation structure itself is a dead area (i.e., charges generated within the isolation structure do not collect in the avalanche multiplication section and are not detected), the larger the area occupied by the isolation structure compared to the APD, the lower the sensitivity. However, if the isolation structure is made unnecessarily thin, another problem can arise: poor electrical connection between the isolation structure and the anode.

[0006] Therefore, in high-definition photoelectric conversion devices, it has been an issue to suppress DCR and sensitivity degradation while maintaining isolation performance between pixels. [Means for solving the problem]

[0007] The present disclosure provides: a first avalanche photodiode and a second avalanche photodiode, each having a first semiconductor region of a first conductivity type in which carriers of the same conductivity type as the signal charge are the majority carriers; 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 that is a conductivity type different from the first conductivity type; a connection portion that electrically connects a contact plug of an anode wiring and the second semiconductor region of the isolation portion, The connection portion is a third semiconductor region of the second conductivity type connected to a contact plug of the anode wiring; a fourth semiconductor region of the second conductivity type disposed between the third semiconductor region and the second semiconductor region, the impurity concentration of the third semiconductor region is higher than the impurity concentration of the second semiconductor region; the impurity concentration of the fourth semiconductor region is lower than the impurity concentration of the third semiconductor region; In 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. Ku , the impurity concentration of the fourth semiconductor region is equal to or lower than the impurity concentration of the second semiconductor region; Includes a photoelectric conversion device.

[0008] The present disclosure provides: a first avalanche photodiode and a second avalanche photodiode, each having a first semiconductor region of a first conductivity type in which carriers of the same conductivity type as the signal charge are the majority carriers; 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 that is a conductivity type different from the first conductivity type; the second conductivity type connection portion electrically connecting the contact plug of the anode wiring and the second semiconductor region of the isolation portion; a fifth semiconductor region of the second conductivity type disposed on the light incident side of the first semiconductor region; a sixth semiconductor region which is a semiconductor region of the first conductivity type having an impurity concentration lower than the impurity concentration of the first semiconductor region, or which is a semiconductor region of the second conductivity type having an impurity concentration lower than the impurity concentration of the fifth semiconductor region; an avalanche multiplication section is formed by the first semiconductor region and the fifth semiconductor region, a width of the separation portion in a first direction in which the first avalanche photodiode and the second avalanche photodiode are aligned side by side is smaller than a width of the connection portion; The sixth semiconductor region is also disposed between the connection portion and the fifth semiconductor region. Crate , the sixth semiconductor region is a semiconductor region of the first conductivity type, and extends to the connection portion in a diagonal direction and to the isolation portion in an opposite side direction; Includes a photoelectric conversion device.

[0009] The present disclosure includes a photoelectric conversion system and an apparatus including the photoelectric conversion device. [Effects of the Invention]

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

[0011] [Figure 1] FIG. 1 is a schematic diagram of a photoelectric conversion device. [Figure 2] FIG. 2 is a schematic diagram of a sensor substrate of the photoelectric conversion device. [Figure 3] FIG. 2 is a schematic diagram of a circuit board of the photoelectric conversion device. [Figure 4] 1 is a diagram illustrating an example of the configuration of a pixel circuit of a photoelectric conversion device. [Figure 5] FIG. 2 is a schematic diagram illustrating driving of a pixel circuit of a photoelectric conversion device. [Figure 6] 1 is a plan view of a photoelectric conversion device according to a first embodiment. [Figure 7] 1 is a cross-sectional view of a photoelectric conversion device according to a first embodiment taken in a diagonal direction. [Figure 8] 1 is a cross-sectional view of a photoelectric conversion device according to a first embodiment taken along an opposite side thereof. [Figure 9] 1 is an enlarged view of a main part of a photoelectric conversion device according to a first embodiment. [Figure 10] FIG. 10 is a plan view of a photoelectric conversion device according to a second embodiment. [Figure 11] FIG. 10 is a cross-sectional view in a diagonal direction of a photoelectric conversion device according to a second embodiment. [Figure 12] 10 is a cross-sectional view of a photoelectric conversion device according to a second embodiment taken along an opposite side thereof. [Figure 13] FIG. 10 is a plan view of a photoelectric conversion device according to a third embodiment. [Figure 14] FIG. 10 is a plan view of a photoelectric conversion device according to a fourth embodiment. [Figure 15] FIG. 10 is a cross-sectional view in a diagonal direction of a photoelectric conversion device according to a fourth embodiment. [Figure 16] 10A and 10B are cross-sectional views of a photoelectric conversion device according to a fifth embodiment taken along a diagonal direction and an opposite side direction. [Figure 17] FIG. 10 is a plan view of a photoelectric conversion device according to a sixth embodiment. [Figure 18] FIG. 10 is a cross-sectional view in a diagonal direction of a photoelectric conversion device according to a sixth embodiment. [Figure 19] FIG. 10 is a cross-sectional view of a photoelectric conversion device according to a sixth embodiment taken along an opposite side. [Figure 20] FIG. 10 is a plan view of a photoelectric conversion device according to a seventh embodiment. [Figure 21] FIG. 10 is a cross-sectional view of a photoelectric conversion device according to an eighth embodiment. [Figure 22] FIG. 13 is a schematic diagram of a photoelectric conversion system according to a ninth embodiment. [Figure 23] FIG. 22 is a schematic diagram of a photoelectric conversion system according to a tenth embodiment. [Figure 24] FIG. 16 is a schematic diagram of a photoelectric conversion system according to an eleventh embodiment. [Figure 25] FIG. 22 is a schematic diagram of a photoelectric conversion system according to a twelfth embodiment. [Figure 26] FIG. 22 is a schematic diagram of a photoelectric conversion system according to a thirteenth embodiment. [Figure 27] FIG. 22 is a schematic diagram of a photoelectric conversion system according to a fourteenth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The embodiments shown below are intended to embody the technical concept of the present invention and are not intended to limit the present invention. The size and positional relationship of components shown in each drawing may be exaggerated for clarity. In the following description, the same components may be designated by the same reference numerals and their description may be omitted.

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, "upper," "lower," "right," "left," and other terms including these terms) will be used as necessary. The use of these terms is intended to facilitate understanding of the 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 planar view refers to a view from a direction perpendicular to the light incident surface of the semiconductor layer. A cross-sectional view refers to a surface perpendicular to the light incident surface of the semiconductor layer. When the light incident surface of the semiconductor layer is a rough surface when viewed microscopically, the planar view is defined based on the light incident surface of the semiconductor layer when viewed macroscopically.

[0015] The semiconductor layer has a first surface and a second surface opposite to the first surface, through which light is incident. In this specification, the depth direction is the direction from the first surface of the semiconductor layer on which the APD is disposed toward the second surface. Hereinafter, the "first surface" may be referred to as the "front surface," and the "second surface" may be referred to as the "rear surface." The "depth" of a point or region in the semiconductor layer refers to the distance from the first surface (front surface) to that point or region. If there is a point (or region) Z1 whose distance (depth) from the first surface is d1 and a point (or region) Z2 whose distance (depth) from the first surface is d2, and d1 > d2, this may be expressed as "Z1 is deeper than Z2" or "Z2 is shallower than Z1." Also, when there is a point (or region) Z3 whose distance (depth) from the first surface is d3 and d1>d3>d2 holds, it can be expressed as "Z3 is at a depth between Z1 and Z2" or "Z3 is between Z1 and Z2 in the depth direction."

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

[0017] In this specification, when the term "impurity concentration" is simply used, it means the net impurity concentration after subtracting the amount compensated by impurities of the opposite conductivity type. "Concentration" refers to the NET doping concentration. A region where the P-type doping concentration is higher than the N-type doping concentration is a P-type semiconductor region. Conversely, a region where the N-type doping concentration is higher than the P-type doping concentration is an N-type semiconductor region.

[0018] First, the configuration common to each embodiment will be described with reference to FIGS.

[0019] FIG. 1 illustrates the configuration of a stacked-type photoelectric conversion device 100. The photoelectric conversion device 100 is configured by stacking and electrically connecting two components, a first member 11 and a second member 21. The first member 11 includes a first semiconductor layer having a photoelectric conversion element 102 (described later) and a first wiring structure. The second member 21 includes a second semiconductor layer having circuits such as a signal processing unit 103 (described later) and a second wiring structure. The photoelectric conversion device 100 is configured by stacking the second semiconductor layer, the second wiring structure, the first wiring structure, and the first semiconductor layer in this order. The photoelectric conversion device 100 is a back-illuminated photoelectric conversion device in which light is incident from the second surface and the second member 21 is disposed on the first surface side. Note that the inventions according to the embodiments and examples can also be applied to photoelectric conversion devices having a front-illuminated structure and to photoelectric conversion devices consisting of a single layer rather than a stacked type.

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

[0021] A pixel region 12 having a sensor function is disposed on the first member 11. Therefore, the first member 11 may be called a sensor member, a sensor substrate, a sensor chip, etc. A circuit region 22 that processes signals detected in the pixel region 12 is disposed on the second member 21. The second member 21 may be called a circuit member, a circuit substrate, a circuit chip, etc.

[0022] 2 is a diagram showing 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 plan view to form a pixel region 12. Here, the left-right direction in FIG. 2 will be referred to as the "row direction," "horizontal direction," "x direction," etc., and the up-down direction in FIG. 2 will be referred to as the "column direction," "vertical direction," "y direction," etc. Furthermore, the direction perpendicular to the plane of FIG. 2 will be referred to as the "depth direction," "z direction," etc.

[0023] The pixel 101 is typically a pixel for forming an image, but when used for TOF (Time of Flight), it does not necessarily have to form an image. That is, the pixel 101 may be a pixel for measuring the time and amount of light that arrives.

[0024] 3 is a configuration diagram of the second member 21. It has a signal processing unit 103 that processes the charges photoelectrically converted by the photoelectric conversion element 102 in FIG. 2, a readout circuit 112, a control pulse generation unit 115, a horizontal scanning circuit unit 111, signal lines 113, a vertical scanning circuit unit 110, and drive lines 116.

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

[0026] The vertical scanning circuit unit 110 receives a control pulse supplied from a control pulse generating unit 115 and supplies the control pulse to each pixel via a driving line 116. The vertical scanning circuit unit 110 uses logic circuits such as a shift register and an address decoder.

[0027] The signal output from the photoelectric conversion element 102 of the pixel is processed by the signal processing unit 103. The signal processing unit 103 is provided with a counter, a memory, etc., and the memory holds digital values.

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

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

[0030] The signal output to the signal line 113 is output via an output circuit 114 to a recording unit or a signal processing unit outside the photoelectric conversion device 100 .

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

[0032] 2 and 3, a plurality of signal processing units 103 are arranged in a region overlapping the pixel region 12 in a plan view. A vertical scanning circuit unit 110, a horizontal scanning circuit unit 111, a readout circuit 112, an output circuit 114, and a control pulse generation unit 115 are arranged so as to overlap between an end of the first member 11 and an end of the pixel region 12 in a plan view. In other words, the first member 11 has the pixel region 12 and a non-pixel region arranged around the pixel region 12. The vertical scanning circuit unit 110, the horizontal scanning circuit unit 111, the readout circuit 112, the output circuit 114, and the control pulse generation unit 115 are arranged in a region overlapping the non-pixel region in a plan view.

[0033] Fig. 4 is an example of a block diagram including the equivalent circuits of Fig. 2 and Fig. 3. In Fig. 4, a photoelectric conversion element 102 having an APD 201 is provided in a first member 11, and the other members are provided in a second member 21.

[0034] The APD 201 generates charge pairs in response to incident light through photoelectric conversion. A voltage VL (first voltage) is supplied to the anode of the APD 201. A voltage VH (second voltage) higher than the voltage VL supplied to the anode is supplied to the cathode of the APD 201. A reverse bias voltage is supplied to the anode and cathode so that the APD 201 performs avalanche multiplication. With this voltage supplied, charges generated by the incident light undergo avalanche multiplication, generating an avalanche current.

[0035] When a reverse bias voltage is supplied, there are two modes: Geiger mode, in which the device operates with the potential difference between the anode and cathode greater than the breakdown voltage, and linear mode, in which the device operates with the potential difference between the anode and cathode close to or less than the breakdown voltage.

[0036] An APD operated in Geiger mode is called a single photon avalanche diode (SPAD). For example, the voltage VL (first voltage) is −30 V and the voltage VH (second voltage) is 1 V. The APD 201 may be operated in either linear mode or Geiger mode. A SPAD is preferable because the potential difference is larger than that of a linear mode APD, resulting in a more pronounced effect in terms of withstand voltage.

[0037] The quench element 202 is connected to a power supply that supplies a voltage VH and the APD 201. The quench element 202 functions as a load circuit (quench circuit) during signal multiplication by avalanche multiplication, and suppresses the voltage supplied to the APD 201 to suppress avalanche multiplication (quench operation). The quench element 202 also functions to compensate for the voltage drop caused by the quench operation. By passing a current, the voltage supplied to the APD 201 is returned to the voltage VH (recharge operation).

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

[0039] The waveform shaping unit 210 shapes the potential change at the cathode of the APD 201 obtained when photons are detected, and outputs a pulse signal. For example, an inverter circuit is used as the waveform shaping unit 210. While an example using one inverter as the waveform shaping unit 210 is shown in FIG. 4, a circuit in which multiple inverters are connected in series, or another circuit having a waveform shaping effect, may also be used.

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

[0041] A control pulse pSEL is supplied to the selection circuit 212 from the vertical scanning circuit unit 110 in Fig. 3 via a drive line 214 in Fig. 4, and switches between electrical connection and disconnection 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] The electrical connection may be switched by disposing a switch such as a transistor between the quench element 202 and the APD 201 or between the photoelectric conversion element 102 and the signal processing unit 103. Similarly, the supply of the voltage VH or the voltage VL to the photoelectric conversion element 102 may be electrically switched using a switch such as a transistor.

[0043] In this embodiment, a configuration using the counter circuit 211 has been described. However, instead of the counter circuit 211, the photoelectric conversion device 100 may be configured to acquire pulse detection timing using a time-to-digital converter (hereinafter referred to as TDC) and a memory. In this case, the generation timing of the pulse signal output from the waveform shaping unit 210 is converted into a digital signal by the TDC. To measure the timing of the pulse signal, a control pulse pREF (reference signal) is supplied to the TDC from the vertical scanning circuit unit 110 in FIG. 3 via a drive line 213. The TDC acquires, as a digital signal, a signal obtained by converting the input timing of the signal output from each pixel via the waveform shaping unit 210 into a relative time based on the control pulse pREF.

[0044] Figures 5A and 5B schematically show the relationship between the operation of the APD and the output signal. Figure 5A is a diagram excerpting 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 referred to as node A, and the output side is referred to as node B. The upper part of Figure 5B shows the waveform change at node A, and the lower part shows the waveform change at node B.

[0045] Between time t0 and time t1, a potential difference of VH-VL is applied to the APD 201. When a photon is incident on the APD 201 at time t1, avalanche multiplication occurs in the APD 201, an avalanche multiplication current flows through the quench element 202, and the voltage at node A drops. When the amount of voltage drop increases further and the potential difference applied to the APD 201 decreases, avalanche multiplication in the APD 201 stops as at time t2, and the voltage level at node A does not drop below a certain value. After that, between time t2 and time t3, a current that compensates for the voltage drop from voltage VL flows to node A, and at time t3, node A settles to its original potential level. At this time, when the output waveform at node A exceeds a certain threshold, The resulting part is waveform-shaped by the waveform shaping section 210 and is output as a signal from nodeB.

[0046] The arrangement of the signal lines 113, the readout circuits 112, and the output circuits 114 is not limited to that shown in Fig. 3. For example, the signal lines 113 may be arranged to extend in the row direction, and the readout circuits 112 may be arranged at the ends of the signal lines 113.

[0047] The photoelectric conversion devices of the respective embodiments will be described below.

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

[0049] As shown in Fig. 6, a plurality of APDs 201 are arranged in a two-dimensional array in the row direction (left-right direction in Fig. 6) and column direction (up-down direction in Fig. 6) on the semiconductor layer 300. For convenience of illustration, only nine APDs 201 arranged in three rows and three columns are shown in Fig. 6, but in an actual product, for example, hundreds of thousands to millions of APDs 201 are formed. One APD 201 corresponds to one pixel.

[0050] The semiconductor layer 300 is provided with an isolation structure 330 for reducing crosstalk between adjacent APDs 201. The isolation structure 330 is formed in a lattice pattern by a plurality of row isolation structures 330X extending in the row direction and a plurality of column isolation structures 330Y extending in the column direction. An APD 201 is disposed in each of the sections divided by the lattice-shaped isolation structures 330. In this embodiment, the section corresponding to one pixel has a substantially square shape in a plan view. The boundaries of the sections are arranged to overlap the isolation structures 330, for example. A cathode wiring contact plug 326 formed in the wiring structure 320 is disposed approximately at the center of the pixel (section), and anode wiring contact plugs 324 are disposed 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 FIGS. 7 and 8, the first member 11 (sensor substrate) has a structure in which a semiconductor layer 300 and a wiring structure 320 are stacked. The surface of the semiconductor layer 300 facing the wiring structure 320 is called the first surface, and the surface opposite the first surface is called the second surface. The semiconductor layer 300 is made of, for example, silicon. A fixed charge film 310, an insulating film 311, a planarization film 312, and the like are stacked in this order on the second surface of the semiconductor layer 300, and microlenses 313 corresponding to each pixel are further provided above them. That is, 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. The following structure can also be applied to the light incident surface. For example, a concave-convex structure, such as at least one concave or convex portion, is arranged on the second surface, which is the light incident surface. The concave-convex structure is formed by the 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 disposed in a recess provided in the semiconductor layer 300. An interface having a refractive index difference that is not parallel to the second surface is formed. With this configuration, incident light is diffracted, thereby improving 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 disposed on 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 preferable. The fixed charge film 310 may be configured with multiple layers. The insulating film 311 is disposed on the fixed charge film 310 over the entire second surface. For example, a silicon oxide film, a silicon oxynitride film, or a silicon nitride film can be suitably used as the insulating film 311. The insulating film 311 may be configured with multiple layers. Although not shown, in addition to the planarization film 312, a filter layer such as a color filter or an infrared light cut filter may be provided on the second surface side of the semiconductor layer 300.

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

[0054] The semiconductor layer 300 includes 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 are added by ion implantation or 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 a 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 a second conductivity type (P-type in this embodiment).

[0055] The first semiconductor region 301 is a semiconductor region of a first conductivity type (N-type in this embodiment) and is provided on a first surface of the semiconductor layer 300. The first semiconductor region 301 in this embodiment is formed in a circular shape in the center of a pixel (section) in plan view, as shown in Fig. 6. A cathode contact plug 326 is connected to the center position 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 arranged on the light incident side (closer to the second surface) than the first semiconductor region 301. The fifth semiconductor region 305 is formed in a layer shape at a predetermined depth so as to divide the first conductivity type epitaxial layer in one pixel (section) into upper and lower parts. The periphery of the fifth semiconductor region 305 is in contact with the separation portion 330 that surrounds the pixel. The first conductivity type epitaxial layer closer to the first surface than the fifth semiconductor region 305 is the sixth semiconductor region 306, and the first conductivity type epitaxial layer closer to the second surface 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 unit AM through a PN junction. Signal charges generated in the eighth semiconductor region 308 by photoelectric conversion are collected in the avalanche multiplication unit AM. In order to improve the sensitivity of the APD 201, it is preferable to increase the size of the eighth semiconductor region 308, which corresponds to the sensitive region.

[0058] The seventh semiconductor region 307 is a semiconductor region of the first conductivity type formed around the first semiconductor region 301. The seventh semiconductor region 307 is also formed in a circular shape in a plan view. Here, the impurity concentrations of the first semiconductor region 301, the seventh semiconductor region 307, and the sixth semiconductor region 306 are as follows: First semiconductor region 301 > Seventh semiconductor region 307 > Sixth semiconductor region 306 That is, the impurity concentration of the first semiconductor region 301 is set to satisfy the relationship: The seventh semiconductor region 307 is set to have the highest impurity concentration, between that of the first semiconductor region 307 and that of the sixth semiconductor region 306. This ensures electrical connection between the cathode and the first semiconductor region 301 (i.e., the APD 201). The seventh semiconductor region 307 also serves as a guard ring to reduce the electric field.

[0059] The ninth semiconductor region 309 is a buried layer of the second conductivity type provided over the entire second surface of the semiconductor layer 300. The ninth semiconductor region 309 serves to suppress noise from the second surface side. 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 can be formed to collect charges.

[0060] The separation unit 330 of this embodiment is formed by a second semiconductor region 302 of the second conductivity type, and suppresses the movement of electrons between pixels by a potential barrier. As shown in FIG. 8 , the second semiconductor region 302 is provided from a predetermined depth D1 in the depth direction from the first surface to a position where it contacts the ninth semiconductor region 309. By limiting the second semiconductor region 302 to the depth D1 and not exposing it to the first surface, it is possible to prevent charges (noise) generated near the first surface from entering the sensitive region via the second conductivity type semiconductor 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. In other words, the second semiconductor region 302 of the separation unit 330 is preferably arranged to separate adjacent pixels at least with respect to the eighth semiconductor region 308, which is the sensitive region, and the fifth semiconductor region 305, which forms the avalanche multiplication unit AM. It can also be said that the second semiconductor region 302 is located at least between a plurality of avalanche multiplication portions 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 and the second semiconductor region 302 of the isolation portion 330. The connection portion in this embodiment is composed of a third semiconductor region 303 connected to the contact plug 324, and a fourth semiconductor region 304 disposed 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 Third semiconductor region 303>Second semiconductor region 302 Third semiconductor region 303>Fourth semiconductor region 304 The impurity concentration of the third semiconductor region 303 is set to satisfy the following relationship. That is, the third semiconductor region 303 has the highest impurity concentration. Specifically, the impurity concentration of the third semiconductor region 303 is preferably at least one order of magnitude higher than the impurity concentrations of the second semiconductor region 302 and the fourth semiconductor region 304. This makes it possible to achieve a stable ohmic junction between the contact plug 324 of the anode wiring and the third semiconductor region 303. Furthermore, by lowering the impurity concentration of the fourth semiconductor region 304, a potential valley can be formed at a depth of the fourth semiconductor region 304, and charge (noise) generated on the contact plug 324 can be prevented from entering the sensitive 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 a value equal to or lower than the impurity concentration of the second semiconductor region 302. Third semiconductor region 303 >> Second semiconductor region 302 ≧ Fourth semiconductor region 304 For example, the impurity concentration of the third semiconductor region 303 is preferably 1.0E 19 [atms / cm 3 ], and the impurity concentrations of the second semiconductor region 302 and the fourth semiconductor region 304 are 1.0E17 to 1.0E18 [atms / cm 3 It is recommended to set it to the order:

[0063] 6, the connection portions (303, 304) are arranged at positions corresponding to the intersections of the row-direction isolation portions 330X and the column-direction isolation portions 330Y. In regions other than the connection portions (third semiconductor regions 303), the second conductivity type semiconductor regions are not exposed on the first surface.

[0064] In plan view, the contact plugs 324 of the anode wiring are arranged at the four corners of one pixel partition, at positions a predetermined distance away from the intersections of the isolation sections 330. The third semiconductor region 303 has a footprint slightly larger than the circumscribed rectangle of the four contact plugs 324 to establish physical and electrical connection with the four contact plugs 324 arranged around one intersection. The footprint shape of the third semiconductor region 303 in this embodiment (the planar shape when projected onto the first surface) is approximately square.

[0065] 6, two APDs 201 arranged diagonally (in the first direction) are positioned symmetrically across the intersection of the isolation region 330 and the third semiconductor region 303. As shown in FIGS. 6 and 7, the sizes of the isolation region 330 and the third semiconductor region 303 are set so that, when comparing the widths in the first direction, the width W1 of the isolation region 330 (intersection) is smaller than the width W2 of the third semiconductor region 303 (connection).

[0066] This configuration minimizes the width of the separation section 330 in a plan view, ensuring a sufficient distance between the separation section 330 and the avalanche multiplication section AM even when the pixel size is reduced. This allows for pixel miniaturization (high definition) and DCR suppression while maintaining inter-pixel isolation. Furthermore, by reducing the width of the separation section 330, which serves as the insensitive region, the size of the sensitive region can be relatively increased, thereby increasing the pixel aperture ratio. This also improves the sensitivity of the photoelectric conversion device. Meanwhile, the third semiconductor region 303, which connects the separation section 330 to the anode wiring, is formed wider than the separation section 330 and has a higher impurity concentration than the second semiconductor region 302. This allows for 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 in the first direction of the fourth semiconductor region 304 is also the same as the width of the third semiconductor region 303, W2. Making the footprint shapes the same in this way has the advantage of facilitating manufacturing, since the third semiconductor region 303 and the fourth semiconductor region 304 can be manufactured using the same mask when manufacturing the semiconductor layer 300. However, it is not essential that the footprint shapes and widths of the third semiconductor region 303 and the fourth semiconductor region 304 be the same, and 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 the same as those of the intersections of the isolation regions 330.

[0068] 9 is an enlarged view of a main part of FIG. 7, and shows a schematic diagram of the layer structure of the semiconductor region directly above the contact plug 324 of the anode wiring and its potential. Directly above the contact plug 324 (indicated by the dashed line in FIG. 9), a third semiconductor region 303, a fourth semiconductor region 304, a sixth semiconductor region 306, and a fifth semiconductor region 305 are arranged in this 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 therebetween 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 fourth semiconductor region 304 has an impurity concentration that is one digit or more 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] According to this configuration, even if electric charge 370 is generated at the junction with contact plug 324, the electric charge 370 cannot cross the potential valley and is collected by the cathode as shown by the dotted arrow in Figure 9. Therefore, it is possible to prevent electric charge (noise) generated at the junction with the anode from entering the eighth semiconductor region 308, which is the sensitive region.

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

[0071] In the above embodiment, the sixth semiconductor region 306 is formed of a semiconductor region of the 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 of a semiconductor region of the 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 type of the first semiconductor region 301, the seventh semiconductor region 307, and the sixth semiconductor region 306 are First semiconductor region 301 > Seventh semiconductor region 307 > Sixth semiconductor region 306 The sixth semiconductor region 306 may be a neutral region, for example. Similarly, the eighth semiconductor region 308 may be formed of a semiconductor region of the second conductivity type having an impurity concentration lower than the impurity concentration of the fifth semiconductor region 305, and may be a neutral region. 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 Eighth semiconductor region 308>sixth semiconductor region 306 The relationship may be set to satisfy the following relationship.

[0072] Example 2 10, 11, and 12 show the structure of the first member 11 (sensor substrate) of the photoelectric conversion device according to Example 2. FIG. 10 is a plan view showing the configuration of the pixel region, and schematically shows the semiconductor layer 300 of the first member 11 as viewed from the first surface side. FIG. 11 is a cross-sectional view taken along line AA (diagonal direction) in FIG. 10, and FIG. 12 is a cross-sectional view taken along line BB (opposite side direction) in FIG. 10. The same reference numerals are used to denote parts corresponding to those in Example 1. Below, configurations different from Example 1 will be described.

[0073] The isolation portion 330 of this embodiment includes a deep trench isolation (DTI) 331, which is an insulator, and a second semiconductor region 302 disposed between the DTI 331 and the APD 201. The DTI 331 of this embodiment includes an insulating film 311 and a fixed charge film 310 disposed between the insulating film 311 and the second semiconductor region 302 of the second conductivity type. The insulating film 311 is preferably a silicon oxide film, a silicon oxynitride film, or a silicon nitride film, and the fixed charge film 310 is preferably an aluminum oxide film or a hafnium oxide film. For example, the DTI 331 is fabricated 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 burying the insulating film 311.

[0074] This configuration also provides the same effects as those of the first embodiment. The provision of TI 331 is expected to further improve the isolation performance between pixels and further suppress crosstalk. The fixed charge film 310 forms a hole accumulation region, further enhancing the suppression effect of DCR and crosstalk.

[0075] In addition, in the isolation portion 330 of this embodiment, as shown in FIG. 12, the second semiconductor region 302 is provided from a predetermined depth D1 in the depth direction from the first surface to a position where it contacts the ninth semiconductor region 309. That is, the second semiconductor region 302 of the second conductivity type does not reach the first surface. Therefore, in areas where the connection portions (303, 304) are not present, the end of the DTI 331 on the first surface side is not covered by the second conductivity type semiconductor region and is in contact with the sixth semiconductor region 306. This structure prevents charge (noise) generated near the first surface from entering the sensitive region via the second conductivity type semiconductor 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 side, but the DTI 331 may be formed to a depth partway through the semiconductor layer 300. For example, the DTI 331 and the second semiconductor region 302 may be made to the same depth, and the bottom of the DTI 331 may be in contact with the connection portions (303, 304). Also, a conductor may be embedded inside the DTI 331.

[0077] Example 3 13 is a schematic diagram showing the semiconductor layer 300 of the photoelectric conversion device according to Example 3 as viewed from the first surface side. The same reference numerals are used to designate parts corresponding to those in the above-described examples. The following describes configurations that differ from those in the above-described examples.

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

[0079] This configuration also provides the same effects as the above-described embodiment. 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 the contact plugs 324 is mirror-symmetric across the row-direction isolation portion 330X and mirror-symmetric across the column-direction isolation portion 330Y. This results in an arrangement in which four contact plugs 324 are gathered around one intersection, making the footprint area of ​​the connection portion equivalent to that of Embodiments 1 and 2. Therefore, a stable ohmic junction with the anode can be achieved. Furthermore, while a reduction in the footprint of the connection portion can be a concern due to the difficulty in forming a mask (resist), which can lead to concerns about a decrease in manufacturing yield, the thinning method of this embodiment does not cause such a problem. Therefore, the configuration of this embodiment is advantageous for miniaturizing pixels.

[0081] Example 4 14 and 15 show the structure of the first member 11 (sensor substrate) of the photoelectric conversion device according to Example 4. FIG. 14 is a plan view showing the configuration of the pixel region, and schematically shows the semiconductor layer 300 of the first member 11 as viewed from the first surface side. FIG. 15 is a cross-sectional view taken along line AA (diagonal direction) in FIG. 14. Parts corresponding to those in the above-described examples are given the same reference numerals. Below, configurations different from those in the above-described examples will be described.

[0082] In this embodiment, the contact plugs 324 and connecting portions of the anode wiring are further thinned out. Specifically, the contact plugs 324 and connecting portions (third semiconductor region 303, fourth semiconductor region 304) are arranged only at positions corresponding to the four corners of a unit consisting of four APD sections arranged in two rows and two columns.

[0083] This configuration also provides the same effects as the above-described embodiment. 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 the contact plugs 324 is mirror-symmetric across the row-direction isolation portion 330X and mirror-symmetric across the column-direction isolation portion 330Y. This results in an arrangement in which four contact plugs 324 are gathered around one intersection, making the footprint area of ​​the connection portion equivalent to that of Embodiments 1 and 2. Therefore, a stable ohmic junction with the anode can be achieved. Furthermore, while a reduction in the footprint of the connection portion can be a concern due to the difficulty in forming a mask (resist), which can lead to concerns about a decrease in manufacturing yield, the thinning method of this embodiment does not cause such a problem. Therefore, the configuration of this embodiment is advantageous for miniaturizing pixels.

[0085] In the configuration of this embodiment, the contact plug 324 and the connection portion are located at only one corner of each pixel section. Therefore, locating the avalanche multiplication portion AM approximately in the center of the section, as in the above-described embodiment, is undesirable because an asymmetric electric field acts on the avalanche multiplication portion AM. Therefore, it is preferable to position the first semiconductor region 301 and the seventh semiconductor region 307 of each of the four sections, arranged in two rows and two columns, at a position offset toward the center of the unit consisting of these four sections. For example, as shown in FIG. 14 , it is preferable to position the first semiconductor region 301 so that the distance L2 between the connection portion (303) and the first semiconductor region 301 is approximately equal to the distance L1 between the isolation portions 330X and 330Y located toward the center of the unit and the first semiconductor region 301. This positioning reduces the possibility of a localized high electric field acting on the first semiconductor region 301.

[0086] Example 5 16A and 16B show the structure of the first member 11 (sensor substrate) of the photoelectric conversion device according to Example 5. FIG. 16A is a cross-sectional view of the semiconductor layer 300 in the diagonal direction, and FIG. 16B is a cross-sectional view of the semiconductor layer 300 in the opposite side direction. The same reference numerals are used to denote parts corresponding to those in the above-described examples. Below, configurations different from those in the above-described examples will be described.

[0087] This embodiment differs from the above-described embodiments in that the second conductivity type connection portion for electrically connecting the anode wiring contact plug 324 and the second semiconductor region 302 of the isolation portion 330 is formed only by the third semiconductor region 303. The relative relationships of the sizes of the respective semiconductor regions and the relative relationships of the impurity concentrations may be set in the same manner as in the above-described embodiments. With this configuration, it is possible to achieve the same effects as in the above-described embodiments.

[0088] 16A and 16B, in this embodiment, the depth D1 of the second semiconductor region 302 at positions where the third semiconductor region 303, which is the connection portion, is greater than the depth D2 of the second semiconductor region 302 at positions other than the position where the third semiconductor region 303 is located. With this structure, in places where no connection portion is located, it is possible to prevent electric charges (noise) generated near the first surface from entering the sensitive region through the semiconductor region of the second conductivity type.

[0089] Example 6 17, 18, and 19 show the structure of the first member 11 (sensor substrate) of the photoelectric conversion device according to Example 6. FIG. 17 is a plan view showing the configuration of the pixel region, and schematically shows the semiconductor layer 300 of the first member 11 as viewed from the first surface side. FIG. 18 is a cross-sectional view taken along line AA (diagonal direction) in FIG. 17, and FIG. 19 is a cross-sectional view taken along line BB (opposite side direction) in FIG. 17. The same reference numerals are used to denote parts corresponding to the above-described examples. Below, configurations different from the above-described examples will be described.

[0090] In this embodiment, an avalanche multiplication unit 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 closer to the second surface than the first semiconductor region 341. A seventh semiconductor region 347 of a first conductivity type acting as a guard ring is formed in a ring shape so as to cover the periphery of the substantially circular first semiconductor region 341.

[0091] A semiconductor region 344 of the second conductivity type is arranged closer to the second surface than the fifth semiconductor region 345, and a ninth semiconductor region 309 of the second conductivity type is arranged on the second surface side of the semiconductor region 344. In this case, it is preferable that the impurity concentration of the ninth semiconductor region 309 is higher than that of the semiconductor region 344. With such a setting, the charge photoelectrically converted in the semiconductor region 344, which is the sensitive region, is collected in the avalanche multiplication unit AM arranged on the first surface side without leaking to the second surface side. This makes it possible to efficiently read out the signal charge.

[0092] In the APD 201 of this embodiment, by applying the separation section 330 and connection section having the same structure as in the above-described embodiment, it is possible to achieve the same effects as in the above-described embodiment.

[0093] Example 7 Variations in the footprint shape of the connection portion will be described with reference to FIGS. 20A to 20C.

[0094] Fig. 20A shows an example in which a substantially square-shaped third semiconductor region 303 is arranged so that the four corners of the square are aligned with the positions of four contact plugs 324. Fig. 20B shows an example in which a substantially square-shaped third semiconductor region 303 is arranged so that the diagonals of the square overlap with the isolation portion 330. Fig. 20C shows an example in which a connection portion is formed by a substantially circular third semiconductor region 303.

[0095] To ensure electrical connection with the anode, the size (width) required for the design of the third semiconductor region 303 is predetermined. For example, assuming that the arrangement of the contact plugs 324 is the same in FIGS. 20A to 20C, the diagonal width of the third semiconductor region 303 must be W or more in any shape. Comparing the area of ​​the third semiconductor region 303 in each shape, the area of ​​the shape in FIG. 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 220A requires the smallest area. Because the third semiconductor region 303 is a source of dark current, it is preferable that its area be small. Therefore, from the viewpoint of minimizing the area, the shape of FIG. 20A is preferable.

[0096] 20B and 20C have the advantage of having no corners within the pixel partition (aperture). For example, if corner 350 exists as in the shape of FIG. 20A, a local high electric field may act on corner 350. From the viewpoint of being less likely to cause such electric field concentration, the shapes of FIG. 20B and 20C, which have no corners, are preferable.

[0097] It should be noted that the shapes in FIGS. 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 FIG. 21 is a cross-sectional view showing an example of the configuration of a stacked photoelectric conversion device 100. As shown in FIG.

[0099] The first member 11 (sensor substrate) has a first semiconductor layer 300 and a first wiring structure 320. The first semiconductor layer 300 is formed with the APD 201, the isolation portion 330, the connection portions (303, 304), and the like described in the above embodiments. The first member 11 is formed with an opening 360 that extends from the first surface (light incident surface) side to the middle of the first wiring structure 320, and a pad 361 is exposed at the bottom of the opening 360. The 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] Second member 21 (circuit board) has second semiconductor layer 420 and second wiring structure 410. Signal processing section 402 having a plurality of semiconductor elements is formed in second semiconductor layer 420. Furthermore, second wiring structure 410 has wiring 401 related to signal processing section 402 formed therein.

[0101] The photovoltaic conversion device 100 is fabricated by stacking the first member 11 and the second member 21 so that the wiring structures 320, 410 face each other. The electrical connection between the first member 11 and the second member 21 is established via the joint 328.

[0102] Example 9 A photoelectric conversion system according to a ninth embodiment will be described with reference to Fig. 22. Fig. 22 is a block diagram showing a schematic configuration of the photoelectric conversion system according to the ninth embodiment.

[0103] The photoelectric conversion devices described in the first to eighth embodiments are applicable to various photoelectric conversion systems. A photoelectric conversion system includes at least a photoelectric conversion device according to any one of the above embodiments and a signal processing unit that processes a signal output from the photoelectric conversion device. Examples of devices to which such photoelectric conversion systems can be applied include digital still cameras, digital camcorders, surveillance cameras, copiers, fax machines, mobile phones, vehicle-mounted cameras, observation satellites, sensors, and measuring instruments. Camera modules equipped with an optical system such as a lens and an imaging device are also included in devices to which photoelectric conversion systems are applied. FIG. 22 illustrates a block diagram of a digital still camera as an example of such devices.

[0104] FIG. 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 having a camera or imaging function. The imaging device IS may further include a package PKG that houses an imaging device IC. The package PKG may include a base to which the imaging device IC is fixed, a lid that faces the imaging device IC, and a connecting member that connects terminals provided on the base with terminals provided on the imaging device IC. The imaging device IS may also mount multiple imaging device ICs side by side in a common package PKG. The imaging device IS may also mount an imaging device IC and other semiconductor device ICs stacked 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 device CU that controls the imaging device IS, a processing device PU that processes signals obtained from the imaging device IS, a display device DU that displays images obtained from the imaging device IS, and a storage device MU that stores images obtained from the imaging device IS.

[0106] Example 10 Regarding the equipment to which the photoelectric conversion system of Example 10 is applied, Figs. 23A and 23B are used. 23A and 23B are diagrams showing the configuration of a photoelectric conversion system and devices according to this embodiment.

[0107] FIG. 23A shows an example of a photoelectric conversion system related to an in-vehicle camera. The photoelectric conversion system 2300 includes an imaging device 2310. The imaging device 2310 is the photoelectric conversion device described in any of the above embodiments. The photoelectric conversion system 2300 includes an image processing unit 2312 that performs image processing on multiple pieces of image data acquired by the imaging device 2310, and a parallax acquisition unit 2314 that calculates parallax (phase difference between parallax images) from the multiple pieces of image data acquired by the photoelectric conversion system 2300. The photoelectric conversion system 2300 also includes 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 a 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 the object. In other words, the distance information is information related to the parallax, the amount of defocus, the distance to the object, etc. The collision determination unit 2318 may determine the possibility of a collision using any of these distance information. The distance information acquisition means may be realized by dedicated hardware, a software module, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or a combination thereof.

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

[0109] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are imaged by the photoelectric conversion system 2300. Fig. 23B shows the photoelectric conversion system 2300 when imaging the area in front of the vehicle (imaging range 2350). A vehicle information acquisition device 2320 sends instructions to the photoelectric conversion system 2300 or the imaging device 2310. Such a configuration can further improve the accuracy of distance measurement.

[0110] Although the above describes an example of control to prevent collision with other vehicles, the photoelectric conversion system can also be applied to control of automatic driving by following other vehicles, control of automatic driving to prevent deviation from a lane, etc. Furthermore, the photoelectric conversion system is not limited to vehicles such as the subject vehicle, but can be applied to moving bodies (moving devices) such as ships, aircraft, and industrial robots. In addition, the photoelectric conversion system can be applied not only to moving bodies but also to a wide range of devices that use object recognition, such as intelligent transport systems (ITS).

[0111] Example 11 An apparatus to which a photoelectric conversion system according to an eleventh embodiment is applied will be described with reference to Fig. 24. Fig. 24 is a block diagram showing an example of the configuration of a range image sensor, which is an example of an apparatus to which the photoelectric conversion system according to this embodiment is applied.

[0112] As shown in FIG. 24, the distance image sensor 1401 includes an optical system 1402, a photoelectric conversion device 1403, and a 1403, 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 a light source device 1411 toward a subject and reflected from the surface of the subject, thereby obtaining a distance image according to the distance to the subject.

[0113] The optical system 1402 is configured to have one or more lenses, and guides image light (incident light) from an object to the photoelectric conversion device 1403 , forming an image on the light receiving surface (sensor section) of the photoelectric conversion device 1403 .

[0114] The photoelectric conversion device 1403 is one of the photoelectric conversion devices of the above-described embodiments, and a distance signal indicating a distance determined from a light receiving signal output from the photoelectric conversion device 1403 is supplied to an 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 conversion device 1403. The distance image (image data) obtained by this image processing is then supplied to a monitor 1405 for display, or supplied to a memory 1406 for storage (recording).

[0116] In the range image sensor 1401 configured in this way, by applying the above-described photoelectric conversion device, it is possible to obtain a more accurate range image.

[0117] Example 12 An apparatus to which a photoelectric conversion system according to Example 12 is applied will be described with reference to Fig. 25. Fig. 25 is a diagram showing an example of a schematic configuration of an endoscopic surgery system that is an apparatus to which the photoelectric conversion system of this example is applied.

[0118] 25 shows an operator (doctor) 1131 performing surgery on a patient 1132 on a patient bed 1133 using an endoscopic surgery system 1003. As shown in the figure, the endoscopic surgery system 1003 is composed of an endoscope 1100, a surgical tool 1110, and a cart 1134 on which various devices for endoscopic surgery are mounted.

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

[0120] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 1101. A light source device 1203 is connected to the endoscope 1100, and light generated by the light source device 1203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 1101, and is irradiated via the objective lens towards an observation target inside the body cavity of the patient 1132. The endoscope 1100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0121] An optical system and a photoelectric conversion device are provided inside the camera head 1102, and light reflected from an observation object (observation light) is focused onto the photoelectric conversion device by the optical system. The observation light is photoelectrically converted by the photoelectric conversion device to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observation image. The photoelectric conversion device may be any of the photoelectric conversion devices described in the above-mentioned embodiments. The image signal is sent to a camera control unit (CCU) 1135 as RAW data.

[0122] The CCU 1135 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and performs overall control of the operations of the endoscope 1100 and the display device 1136. Furthermore, the CCU 1135 receives an image signal from the camera head 1102, and performs various types of image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0123] Under the control of the CCU 1135 , the display device 1136 displays an image based on the image signal that has been subjected to image processing by the CCU 1135 .

[0124] The light source device 1203 is configured from a light source such as an LED (Light Emitting Diode), and supplies the endoscope 1100 with irradiation light when photographing an operation site or the like.

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

[0126] The control device 1138 controls the driving of the energy treatment device 1112 for cauterizing tissue, cutting, sealing blood vessels, or the like.

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

[0128] Furthermore, the light source device 1203 may be controlled to change the intensity of light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 1102 in synchronization with the timing of the change in the light intensity to acquire images in a time-division manner and combining the images, it is possible to generate an image with a high dynamic range that is free of so-called blocked-up shadows and blown-out highlights.

[0129] The light source device 1203 may also be configured to supply light in a predetermined wavelength band corresponding to special light observation. Special light observation utilizes, for example, the wavelength dependency of light absorption in body tissue. Specifically, specific tissue, such as blood vessels on the surface of the mucous membrane, can be photographed with high contrast by irradiating light with a narrower band than the light (i.e., white light) used in normal observation. Alternatively, special light observation may involve fluorescence observation, in which an image is obtained using fluorescence generated by irradiating excitation light. Fluorescence observation can involve irradiating excitation light onto body tissue and observing the fluorescence from the body tissue, or locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the body tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 1203 may be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0130] Example 13 Regarding the equipment to which the photoelectric conversion system according to Example 13 is applied, FIGS. 26A and 26B are shown. This will be used to explain.

[0131] FIG. 26A shows glasses 1600 (smart glasses) that are a device to which the photoelectric conversion system of this embodiment is applied. The glasses 1600 have a photoelectric conversion device 1602. The photoelectric conversion device 1602 is the photoelectric conversion device described in each of the above embodiments. A display device including a light-emitting device such as an OLED or LED may be provided on the back side of the lens 1601. There may be one or more photoelectric conversion devices 1602. Furthermore, 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 FIG. 26A.

[0132] The glasses 1600 further include a control device 1603. The control device 1603 functions as a power source that supplies power to the photoelectric conversion device 1602 and the display device. The control device 1603 also controls the operations of the photoelectric conversion device 1602 and the display device. The control device 1603 also functions as a signal processing unit that processes signals output from the photoelectric conversion device 1602. The lens 1601 is formed with an optical system for focusing light onto the photoelectric conversion device 1602.

[0133] FIG. 26B shows glasses 1610 (smart glasses) that are a device to which the photoelectric conversion system of this embodiment is applied. The arrangement of the photoelectric conversion system differs from that of FIG. 26A. The glasses 1610 include 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. A lens 1611 is formed with an optical system for projecting light emitted from the photoelectric conversion device in the control device 1612 and the display device, and an image is projected onto the lens 1611. The control device 1612 functions as a power source that supplies power to the photoelectric conversion device and the display device, and controls the operation of the photoelectric conversion device and the display device. The control device 1612 may also include a gaze detection unit that detects the gaze of the wearer. Infrared light may be used for gaze detection. The infrared light emitter emits infrared light toward the eyeball of a user gazing at a displayed image. An imaging unit with a light receiving element detects the emitted infrared light reflected from the eyeball, thereby obtaining an image of the eyeball. By providing a reduction means for reducing the amount of light from the infrared light emitting section to the display section in a plan view, degradation of image quality is reduced.

[0134] The gaze of the user relative to the displayed image is detected from an image of the eyeball obtained by capturing infrared light. Any known method can be used for gaze detection using an image of the eyeball. One example is a gaze detection method based on the Purkinje image formed by reflection of irradiated light on the cornea.

[0135] More specifically, gaze detection processing is performed based on the pupil-corneal reflex method, which calculates a gaze vector representing the direction (rotation angle) of the eyeball based on the pupil image and Purkinje image included in the captured image of the eyeball, thereby detecting the user's gaze.

[0136] The display device of this embodiment may have a photoelectric conversion device having a light receiving element, and may control the image displayed on the display device based on information on the user's line of sight from the photoelectric conversion device.

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

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

[0139] Note that AI may be used to determine the first field of view area and areas with high priority. The AI ​​may be a model configured to estimate the angle of gaze and the distance to an object in the line of sight from an image of the eyeball, using as training data an image of the eyeball and the direction in which the eyeball in the image was actually looking. The AI ​​program may be included in the display device, the photoelectric conversion device, or an external device. If included in an external device, it is transmitted to the display device via communication.

[0140] When display control is performed based on visual recognition detection, the present invention is preferably applied to smart glasses that further include a photoelectric conversion device for capturing images of the outside world. The smart glasses can display captured external information in real time.

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

[0142] 27A and 27B are diagrams showing an example of an electronic device 1500 equipped with a photoelectric conversion device. Fig. 27A shows the front side of the electronic device 1500, and Fig. 27B shows the back side of the electronic device 1500.

[0143] 27A, a display 1510 that displays an image is disposed in the center of the surface of electronic device 1500. Then, along the upper side of the surface of electronic device 1500, front cameras 1521 and 1522 that use photoelectric conversion devices, an IR light source 1530 that emits infrared light, and a visible light source 1540 that emits visible light are disposed.

[0144] Also, as shown in FIG. 27B, rear cameras 1551 and 1552 using photoelectric conversion devices, 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 surface of electronic device 1500.

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

[0146] (others) Various devices have been described in the above embodiments, but a mechanical device may also be provided. The mechanical device in the camera can drive optical components for zooming, focusing, and shutter operation. Alternatively, the mechanical device in the camera can move a photoelectric conversion device for vibration reduction.

[0147] The equipment may also be transportation equipment such as a vehicle, a ship, or an aircraft. A mechanical device in transportation equipment can be used as a moving device. Equipment as transportation equipment is suitable for transporting a photoelectric conversion device or for assisting and / or automating driving (piloting) using a photographing function. A processing device for assisting and / or automating driving (piloting) can perform processing to operate the mechanical device as a moving device based on information obtained by the photoelectric conversion device.

[0148] The present invention is not limited to the above-described embodiments and can be modified in various ways. For example, adding a portion of one of the embodiments to another embodiment or substituting a portion of the other embodiment is also included in the present invention. Note that the above-described embodiments are merely illustrative examples of how the present invention can be implemented, and the technical scope of the present invention should not be interpreted as being limited by these examples. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features. [Explanation of symbols]

[0149] 100: Photoelectric conversion device 201: Avalanche photodiode 301: First semiconductor region 302: Second semiconductor region 303: Third semiconductor region 304: Fourth semiconductor region 324: Anode wiring contact plug 330: Separation part

Claims

1. a first avalanche photodiode and a second avalanche photodiode each having a first semiconductor region of a first conductivity type in which carriers of the same conductivity type as the signal charge are the majority carriers; 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 that is a conductivity type different from the first conductivity type; a connection portion that electrically connects a contact plug of an anode wiring and the second semiconductor region of the isolation portion, The connection portion is a third semiconductor region of the second conductivity type connected to a contact plug of the anode wiring; a fourth semiconductor region of the second conductivity type disposed between the third semiconductor region and the second semiconductor region, the impurity concentration of the third semiconductor region is higher than the impurity concentration of the second semiconductor region; the impurity concentration of the fourth semiconductor region is lower than the impurity concentration of the third semiconductor region; a width of the separation portion in a first direction in which the first avalanche photodiode and the second avalanche photodiode are aligned side by side; the impurity concentration of the fourth semiconductor region is equal to or lower than the impurity concentration of the second semiconductor region; Photoelectric conversion device.

2. a fifth semiconductor region of the second conductivity type that is disposed on a light incident side of the first semiconductor region, an avalanche multiplication section is formed by the first semiconductor region and the fifth semiconductor region; The photoelectric conversion device according to claim 1 .

3. a sixth semiconductor region disposed between the connection portion and the fifth semiconductor region; the sixth semiconductor region is a semiconductor region of the first conductivity type having an impurity concentration lower than an impurity concentration of the first semiconductor region, or a semiconductor region of the second conductivity type having an impurity concentration lower than an impurity concentration of the fifth semiconductor region; The photoelectric conversion device according to claim 2 .

4. a width of the third semiconductor region in the first direction and a width of the fourth semiconductor region in the first direction are the same; The photoelectric conversion device according to any one of claims 1 to 3.

5. a first avalanche photodiode and a second avalanche photodiode each having a first semiconductor region of a first conductivity type in which carriers of the same conductivity type as the signal charge are the majority carriers; 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 that is a conductivity type different from the first conductivity type; the second conductivity type connection portion electrically connecting the contact plug of the anode wiring and the second semiconductor region of the isolation portion; a fifth semiconductor region of the second conductivity type disposed on a light incident side of the first semiconductor region; a sixth semiconductor region which is a semiconductor region of the first conductivity type having an impurity concentration lower than that of the first semiconductor region, or which is a semiconductor region of the second conductivity type having an impurity concentration lower than that of the fifth semiconductor region, an avalanche multiplication section is formed by the first semiconductor region and the fifth semiconductor region, a width of the separation portion in a first direction in which the first avalanche photodiode and the second avalanche photodiode are aligned side by side; the sixth semiconductor region is also disposed between the connection portion and the fifth semiconductor region, the sixth semiconductor region is a semiconductor region of the first conductivity type, and extends to the connection portion in a diagonal direction and to the isolation portion in an opposite side direction; Photoelectric conversion device.

6. the connection portion is disposed on a first surface of the semiconductor layer; the second semiconductor region is disposed at a position deeper than the connection portion within the semiconductor layer when viewed from the first surface, a depth of the second semiconductor region at a position where the connection portion is disposed is different from a depth of the second semiconductor region at other positions; The photoelectric conversion device according to claim 5 .

7. a depth of the second semiconductor region at a position where the connection portion is disposed is greater than a depth of the second semiconductor region at other positions; The photoelectric conversion device according to claim 6 .

8. the isolation section further includes an insulator that isolates the first avalanche photodiode and the second avalanche photodiode, the second semiconductor region is disposed between the insulator and each avalanche photodiode; The photoelectric conversion device according to any one of claims 1 to 7.

9. the insulator has a fixed charge film disposed between the second semiconductor regions; The photoelectric conversion device according to claim 8 .

10. 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 8 or 9.

11. the separation section is formed in a lattice shape 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 disposed in each of the sections divided by the lattice-shaped separating portion, and the first avalanche photodiode and the second avalanche photodiode are avalanche photodiodes arranged diagonally in the sections; the connection portion is formed at an intersection of the row direction separator and the column direction separator. The photoelectric conversion device according to any one of claims 1 to 10.

12. the connection portions are formed at the four intersections corresponding to the four corners of the section of each avalanche photodiode; The photoelectric conversion device according to claim 11 .

13. the connection portions are formed at two of the intersections corresponding to diagonal corners of the sections of each avalanche photodiode; The photoelectric conversion device according to claim 11 .

14. the connection portions are formed at the four intersections corresponding to the four corners of a unit consisting of four compartments in two rows and two columns, The photoelectric conversion device according to claim 11 .

15. the first semiconductor region of each of the four sections constituting the unit is disposed so as to be offset toward the center of the unit; The photoelectric conversion device according to claim 14.

16. The photoelectric conversion device according to any one of claims 1 to 15, a signal processing unit that processes a signal output from the photoelectric conversion device; A photoelectric conversion system having:

17. The photoelectric conversion device according to any one of claims 1 to 15, an optical system corresponding to the photoelectric conversion device; a control device that controls the photoelectric conversion device; a processing device that processes a signal output from the photoelectric conversion device; a display device that displays information obtained by the photoelectric conversion device; a storage device that stores information obtained by the photoelectric conversion device; and a mechanical device that operates based on information obtained by the photoelectric conversion device; Equipment comprising:

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