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

Abstract

To provide a technique advantageous for suppressing crosstalk.SOLUTION: A photoelectric conversion device comprises: a semiconductor layer that has a first principal surface and a second principal surface and a first avalanche photodiode and second avalanche photodiode adjacent to each other; and a trench extending from the first principal surface toward the second principal surface. At least part of the trench is arranged between the first avalanche photodiode and the second avalanche photodiode, where a first conductive part and a second conductive part are arranged at the trench. In orthogonal projection for the first principal surface, the first conductive part and the second conductive part are arranged so as to be arranged away from each other.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion device, a photoelectric conversion system, a moving body, and equipment.

Background Art

[0002] An avalanche photodiode (APD) capable of detecting light at the single-photon level is known. Patent Document 1 shows a single-photon avalanche photodiode (SPAD) that can be used for detecting one photon by applying a high reverse bias to a pn junction to form a high electric field region (avalanche multiplication region).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When avalanche emission occurs in which carriers excited in the high electric field region emit photons during carrier multiplication, there is a possibility of crosstalk in which light is detected by pixels adjacent to the pixel where the emission has occurred.

[0005] An object of the present invention is to provide a technique advantageous for suppressing crosstalk.

Means for Solving the Problems

[0006] In view of the above problems, a photoelectric conversion element according to an embodiment of the present invention has a first main surface and a second main surface, and includes a semiconductor layer provided with a first avalanche photodiode and a second avalanche photodiode adjacent to each other, and a trench extending from the first main surface toward the second main surface. The photoelectric conversion device is characterized in that at least a part of the trench is disposed between the first avalanche photodiode and the second avalanche photodiode, a first conductive portion and a second conductive portion are disposed in the trench, and in a normal projection onto the first main surface, the first conductive portion and the second conductive portion are spaced apart from each other.

Effect of the Invention

[0007] According to the present invention, a technique advantageous for suppressing crosstalk can be provided.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0010] First, an avalanche photodiode (hereinafter sometimes referred to as APD) that can be used in the photoelectric conversion device 100 described below will be described with reference to FIGS. 1 to 5. FIG. 1 is a diagram showing a configuration example of the photoelectric conversion device 100. The photoelectric conversion device 100 can be configured by laminating and electrically connecting two substrates, a sensor substrate 11 (hereinafter sometimes simply referred to as substrate 11) and a circuit substrate 21. That is, the photoelectric conversion device 100 may be a stacked type device. As will be described later, a semiconductor layer 301 or the like in which a plurality of pixels 101 are arranged is arranged on the substrate 11. A pixel region 12 including a plurality of pixels 101 is arranged on the substrate 11. A circuit region 22 that processes the signals detected in the pixel region 12 is arranged on the circuit substrate 21.

[0011] FIG. 2 is a diagram showing an arrangement example of the substrate 11. Pixels 101 each having a photoelectric conversion element 102 including an APD are arranged in a two-dimensional array in the orthographic projection onto the main surface 391 of the substrate 11 to form a pixel region 12. The pixel 101 is typically a pixel for generating an image, but when used in a distance measuring device using the Time of Flight (ToF) method, it is not necessarily required to generate an image. That is, the pixel 101 may be configured to measure the arrival time and the amount of light of the light.

[0012] FIG. 3 is a diagram showing a configuration example of the circuit board 21. The circuit board 21 includes a signal processing circuit 103 that processes charges photoelectrically converted by the photoelectric conversion element 102 shown in FIG. 2, a readout circuit 112, a control pulse generation circuit 115, a horizontal scanning circuit 111, signal lines 113, a vertical scanning circuit 110, and the like. The signal processing circuit 103 shown in FIG. 3 may be arranged so as to correspond to each of the pixels 101 shown in FIG. 2. In that case, the pixel 101 (photoelectric conversion element 102) and the signal processing circuit 103 may be electrically connected via connection wiring provided for each pixel 101.

[0013] The vertical scanning circuit 110 receives the control pulse supplied from the control pulse generation circuit 115 and supplies the control pulse to each pixel 101 via the drive line 116. Logic circuits such as a shift register and an address decoder may be used for the vertical scanning circuit 110.

[0014] The signal output from the pixel 101 is processed by the signal processing circuit 103. A counter, a memory, and the like may be provided in the signal processing circuit 103. The count value counted by the counter may be held as a digital value in the memory.

[0015] The horizontal scanning circuit 111 inputs a control pulse for sequentially selecting each column to the signal processing circuit 103 in order to read a signal from the memory of the signal processing circuit 103 corresponding to each pixel 101 in which the digital signal is held. For the selected column, a signal is output from the signal processing circuit 103 corresponding to the pixel 101 selected by the vertical scanning circuit 110 to the signal line 113. The signal output to the signal line 113 is output to a recording unit or a signal processing unit outside the photoelectric conversion device 100 via the output circuit 114.

[0016] The arrangement of the pixels 101 in the pixel region 12 shown in FIG. 2 is not necessarily limited to a two-dimensional array. The pixels 101 may be arranged in a one-dimensional manner. The functions of the signal processing circuit 103 do not necessarily have to be provided one by one for all the pixels 101 (photoelectric conversion elements 102). For example, one signal processing circuit 103 may be shared by a plurality of pixels 101 (photoelectric conversion elements 102), and signal processing may be performed sequentially.

[0017] As shown in FIGS. 2 and 3, in the orthographic projection onto the pixel region 12, a plurality of signal processing circuits 103 may be arranged in the region overlapping the pixel region 12. Also, a vertical scanning circuit 110, a horizontal scanning circuit 111, a readout circuit 112, an output circuit 114, a control pulse generation circuit 115, etc. may be arranged so as to overlap between the edge of the substrate 11 and the edge of the pixel region 12. In other words, the substrate 11 has the pixel region 12 and a non-pixel region arranged around the pixel region 12. In that case, the vertical scanning circuit 110, the horizontal scanning circuit 111, the readout circuit 112, the output circuit 114, and the control pulse generation circuit 115 may be arranged in the region overlapping the non-pixel region.

[0018] FIG. 4 is an example of a block diagram including an equivalent circuit focusing on one pixel 101 (photoelectric conversion element 102). In FIG. 4, the photoelectric conversion element 102 including the APD 201 is provided on the substrate 11, and the other components are provided on the circuit board 21.

[0019] The APD 201 generates charge pairs corresponding to incident light by photoelectric conversion. A potential VL is supplied to the anode of the APD 201. A potential VH higher than the potential VL supplied to the anode is supplied to the cathode of the APD 201. A reverse bias voltage is supplied between the anode and the cathode so that the APD 201 performs an avalanche multiplication operation. By supplying such a reverse bias voltage, the charges generated by the incident light cause avalanche multiplication, and an avalanche current is generated.

[0020] When a reverse bias voltage is supplied to APD201, there are a Geiger mode in which the potential difference (voltage) between the anode and the cathode is operated at a potential difference greater than the breakdown voltage, and a linear mode in which the potential difference between the anode and the cathode is operated at a potential difference near or below the breakdown voltage. An APD operated in the Geiger mode is called a Single Photon Avalanche Diode (SPAD). For example, the potential VL is -30V and the potential VH is 1V. APD201 may be operated in the linear mode or the Geiger mode.

[0021] The quench element 202 is connected between the power supply that supplies the potential VH and APD201. The quench element 202 functions as a load circuit (quench circuit) during signal multiplication by avalanche multiplication, and has the function of suppressing the voltage supplied to APD201 to suppress avalanche multiplication (quench operation). Further, the quench element 202 has the function of returning the voltage supplied to APD201 to the voltage (VH - VL) by flowing the current corresponding to the voltage drop during the quench operation (recharge operation).

[0022] The signal processing circuit 103 may include a waveform shaping circuit 210, a counter circuit 211, and a selection circuit 212. In this specification, the signal processing circuit 103 may have any one of the waveform shaping circuit 210, the counter circuit 211, and the selection circuit 212.

[0023] The waveform shaping circuit 210 shapes the potential change of the cathode of APD201 obtained at the time of photon detection and outputs a pulse signal. As the waveform shaping circuit 210, for example, an inverter circuit is used. In the configuration shown in FIG. 4, an example in which one inverter is used as the waveform shaping circuit 210 is shown. However, the present invention is not limited to this, and as the waveform shaping circuit 210, a circuit in which a plurality of inverters are connected in series may be used, or another circuit having a waveform shaping effect may be used.

[0024] The counter circuit 211 counts the pulse signal output from the waveform shaping circuit 210 and holds the count value. Further, when the control pulse pRES is supplied from the vertical scanning circuit 110 shown in FIG. 3 via the drive line 213 corresponding to a part of the drive line 116 shown in FIG. 3, the signal held in the counter circuit 211 is reset.

[0025] The selection circuit 212 is supplied with the control pulse pSEL from the vertical scanning circuit 110 via the drive line 214 corresponding to a part of the drive line 116 shown in FIG. 3, and switches the 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.

[0026] A switch element such as a transistor may be arranged between the quench element 202 and the APD 201, or between the photoelectric conversion element 102 and the signal processing circuit 103 so that the electrical connection can be switched. Similarly, the supply of the potential VH or the potential VL supplied to the photoelectric conversion element 102 may be electrically switchable using a switch element such as a transistor.

[0027] In the present embodiment, a configuration in which the counter circuit 211 is arranged in the signal processing circuit 103 is shown. However, the present invention is not limited to this, and a time-digital conversion circuit (TDC) and a memory may be used instead of the counter circuit 211 so that the photoelectric conversion device 100 acquires the pulse detection timing. In that case, the generation timing of the pulse signal output from the waveform shaping circuit 210 is converted into a digital signal by the TDC. The control pulse pREF (reference signal) is supplied to the TDC from the vertical scanning circuit 110 via the drive line 116 for measuring the timing of the pulse signal. The TDC acquires, as a digital signal, a signal when the input timing of the signal output from each pixel 101 via the waveform shaping circuit 210 is a relative time with reference to the control pulse pREF.

[0028] In addition, in the configuration shown in FIG. 4, an example is shown in which a quenching element 202, a waveform shaping circuit 210, a counter circuit 211, and a selection circuit 212 are arranged on one circuit board 21, but the present invention is not limited to this. For example, the quenching element 202 and the waveform shaping circuit 210 may be arranged on one substrate, and the counter circuit 211 and the selection circuit 212 may be arranged on another substrate, and those substrates may be laminated.

[0029] FIGS. 5(a) and 5(b) are diagrams schematically showing the relationship between the operation of the APD 201 and the output signal. FIG. 5(a) is a diagram excerpting the APD 201, the quenching element 202, and the waveform shaping circuit 210 shown in FIG. 4. Here, the input side of the waveform shaping circuit 210 is defined as node A, and the output side is defined as node B. FIG. 5(b) shows the waveform changes of node A and node B.

[0030] From time t0 to time t1, a potential difference (voltage) of potential VH - potential VL is applied to the APD 201. When photons enter the APD 201 at time t1, avalanche multiplication occurs in the APD 201, an avalanche multiplication current flows through the quenching element 202, and the potential of node A drops. When the voltage drop amount further increases and the potential difference applied to the APD 201 decreases, as shown at time t2, the avalanche multiplication of the APD 201 stops, and the potential level of node A no longer drops below a certain value. Thereafter, between time t2 and time t3, a current that compensates for the voltage drop flows through node A from potential VL, and at time t3, node A stabilizes at the original potential level. At this time, the portion of the output waveform at node A that exceeds a certain threshold is waveform-shaped by the waveform shaping circuit 210 and output as a signal to node B.

[0031] The arrangement of the signal line 113, the readout circuit 112, and the output circuit 114 is not limited to the configuration shown in FIG. 3. For example, the signal line 113 may be arranged to extend in the row direction (the horizontal direction in FIG. 3), and the readout circuit 112 may be arranged at the end where the signal line 113 extends.

[0032] Next, the configuration of the pixel 101 arranged in the photoelectric conversion device 100 of the present embodiment will be described in detail. FIGS. 6(a) and 6(b) are plan views showing the configuration of the pixel 101 arranged in the pixel region 12. FIG. 7(a) is a cross-sectional view taken along the line A-A' shown in FIG. 6(a), and FIG. 7(b) is a cross-sectional view taken along the line B-B' shown in FIG. 6(a). FIG. 6(a) shows a plane on the main surface 391 of the semiconductor layer 301 shown in FIGS. 7(a) and 7(b). Further, FIG. 6(b) shows the outer edge 332A of the pixel 101 of the wiring pattern 331A connected to the semiconductor region 311 that functions as the cathode of the APD 201, and the inner edge 332B of the pixel 101 of the wiring pattern 331B connected to the semiconductor region 312 that functions as the anode of the APD 201. The photoelectric conversion device 100 shown in FIGS. 6(a), 6(b), 7(a), and 7(b) has a so-called surface illumination type configuration.

[0033] A plurality of pixels 101 are arranged on a substrate 11 made of a semiconductor material in the photoelectric conversion device 100. Each of the plurality of pixels 101 includes an APD 201 formed in a semiconductor layer 301 provided on the substrate 11. It can also be said that the semiconductor layer 301 having the main surface 391 and the main surface 392 includes the APD 201. Each pixel 101 (APD 201) is separated by a trench 324 extending from the main surface 391 to the main surface 392 of the semiconductor layer 301.

[0034] Each pixel 101 includes semiconductor regions 311, 313, 315, and 316 of the same conductivity type. Further, the pixel 101 includes semiconductor regions 312, 314, 317, and 319 of a conductivity type opposite to that of the semiconductor regions 311, 313, 315, and 316. For example, the semiconductor regions 311, 313, 315, and 316 can be N-type semiconductor regions, and the semiconductor regions 312, 314, 317, and 319 can be P-type semiconductor regions. Examples of the semiconductor material used for the substrate 11 include silicon. Therefore, the semiconductor regions 311 to 317 and 319 can be regions in which impurities corresponding to the conductivity type are implanted into silicon. For example, the semiconductor regions 311, 312, 313, 314, 315, 317, and 319 may be formed in the N-type semiconductor layer 301 (semiconductor region 316) using an ion implantation method or the like.

[0035] In the configurations shown in FIGS. 7(a) and 7(b), light is incident from the upper side of the figure. That is, in the semiconductor layer 301, the main surface 391 becomes the light incident surface. An N-type semiconductor region 311 is disposed near the main surface 391 of the semiconductor layer 301, and an N-type semiconductor region 313 is disposed around it. In the orthographic projection of the semiconductor layer 301 onto the main surface 391, a P-type semiconductor region 312 is disposed at a position overlapping the semiconductor region 311 and the semiconductor region 313. Hereinafter, the expression "the semiconductor regions overlap" represents the overlap of the respective semiconductor regions in the orthographic projection onto the main surface 391 of the semiconductor layer 301. The expression "overlap" may be used in the same way in other configurations. An N-type semiconductor region 315 is further disposed at a position overlapping the semiconductor region 312, and an N-type semiconductor region 316 is disposed around it.

[0036] The semiconductor region 311 is a region with a higher N-type impurity concentration than the semiconductor regions 313 and 315. A PN junction is formed between the P-type semiconductor region 312 and the N-type semiconductor region 311. By making the impurity concentration of the semiconductor region 312 lower than that of the semiconductor region 311, all regions of the semiconductor region 312 that overlap the center of the semiconductor region 311 become depletion layer regions when a reverse bias is applied. In that case, the potential difference between the semiconductor region 311 and the semiconductor region 312 becomes larger than the potential difference between the semiconductor region 312 and the semiconductor region 315. Furthermore, this depletion layer region extends to a part of the semiconductor region 311, and a strong electric field is induced in the depletion layer region. Due to this strong electric field, avalanche multiplication is induced in the depletion layer region that extends to a part of the semiconductor region 311, and a current based on the amplified charges is output as signal charges. When the light incident on the pixel 101 is photoelectrically converted and avalanche multiplication is induced in this depletion layer region (avalanche multiplication region), the generated N-type charges are collected in the first semiconductor region 311.

[0037] The semiconductor region 311 is connected to the wiring pattern 331A via the contact plug 330A. The semiconductor region 312 is connected to the wiring pattern 331B via the semiconductor regions 317, 319, and the contact plug 330B. By making the impurity concentration of the semiconductor region 319 higher than that of the semiconductor region 317, the contact resistance between the semiconductor region 319 and the contact plug 330B is reduced.

[0038] In FIGS. 7(a) and 7(b), the semiconductor region 313 and the semiconductor region 315 are formed to have approximately the same size in the planar direction, but the size of each semiconductor region is not limited to this. For example, the semiconductor region 315 may be formed larger than the semiconductor region 313, and charges may be collected from a wider range into the semiconductor region 311. Also, the semiconductor region 313 may be a P-type semiconductor region instead of an N-type semiconductor region. In this case, the impurity concentration of the semiconductor region 313 is set lower than the impurity concentration of the semiconductor region 312. This is because if the impurity concentration of the semiconductor region 313 is too high, an avalanche multiplication region may be formed between the semiconductor region 313 and the semiconductor region 311, and the Dark Count Rate (DCR) may increase.

[0039] As described above, each pixel 101 (APD 201) is separated by a trench 324. A plurality of conductive portions 325 are arranged in the trench 324 at intervals from each other. The conductive portion 325 can be, for example, a metal such as tungsten (W), copper (Cu), or silver (Ag) embedded in the trench 324. Further, a layer such as titanium nitride (TiN) or aluminum containing copper (AlCu) may be arranged on the conductive portion 325 as a barrier metal or the like. By arranging the conductive portion 325 in the trench 324 that separates the pixels 101, it is possible to suppress crosstalk in which light is detected by the pixel 101 adjacent to the pixel 101 where light emission has occurred even when avalanche light emission occurs during avalanche multiplication.

[0040] Also, in the trench 324, the conductive portions 325 are arranged at intervals from each other, and an insulator 326 is arranged between the adjacent conductive portions 325. Light rays incident on the pixel 101 while being inclined from the normal direction of the main surface 391 of the semiconductor layer 301 can enter the trench 324. In that case, if the pixel 101 is surrounded by the conductive portions 325, part of the light incident on the trench 324 may be absorbed by the conductive portions 325. On the other hand, in the present embodiment, the conductive portions 325 arranged in the trench 324 are arranged at intervals from each other. Therefore, absorption of the light obliquely incident on the pixel 101 by the conductive portions 325 is suppressed. As a result, the sensitivity of the pixel 101 (APD 201) is improved.

[0041] As shown in FIG. 7(b), wiring patterns 331B may be connected to the respective conductive portions 325. In that case, a common potential may be supplied to each of the conductive portions 325. Also, in that case, the same potential as the semiconductor region 312 that functions as the anode of the APD 201, to which the potential is supplied via the wiring pattern 331B, may be applied to the respective conductive portions 325. Thereby, the effect of reducing the DCR can be obtained.

[0042] Here, among the APDs 201 arranged for each pixel 101, as shown in FIG. 6(a), the APDs 201a and 201b arranged adjacent to each other will be described. The APDs adjacent to each other refer to two APDs 201 between which no other APD 201 is arranged. At least a part of the trench 324 is arranged between the APD 201a and the APD 201b. The trench 324 further includes a portion arranged to surround the APD 201a and a portion arranged to surround the APD 201b. In that case, in the orthographic projection onto the main surface 391 of the semiconductor layer 301, the conductive portion 325 arranged between the APD 201a and the APD 201b arranged adjacent to each other may include a portion arranged between the center of the APD 201a and the center of the APD 201b. The center of the APD 201 may be the geometric centroid position of the semiconductor region 311 or the semiconductor region 312 in the orthographic projection onto the main surface 391 of the semiconductor layer 301. Also, there may be a case where it is difficult to distinguish each of the semiconductor regions 311 to 317 and 319. In that case, the center of the APD 201 may be the geometric centroid position of the semiconductor region surrounded by the trench 324 in the orthographic projection onto the main surface 391 of the semiconductor layer 301.

[0043] Also, as shown in FIG. 6(a), in the orthographic projection onto the main surface 391 of the semiconductor layer 301, the portions of the trench 324 arranged to surround the APDs 201a and 201b respectively may have a polygonal shape sharing one side. Also, in that case, the conductive portion 325 may be arranged so as to intersect a virtual line connecting the center of the APD 201a and the center of the APD 201b on the shared side of the polygon. Further, as shown in FIG. 6(a), only one conductive portion 325 may be arranged on the shared side, and no other conductive portion 325 may be arranged. However, it is not limited thereto, and two or more conductive portions 325 may be arranged separately from each other on one side of the trench 324 surrounding the APDs 201a and 201b.

[0044] In the configurations shown in FIGS. 6(a), 7(a), and 7(b), conductive portions 325 are arranged such that they intersect virtual lines connecting the centers of adjacent APDs 201 at the side portions of the polygonal shape surrounding the APD 201 in the trench 324. Further, the conductive portions 325 are not arranged at positions including the vertices of the polygonal shape surrounding the APD in the trench 324. In the side portions of the polygonal shape surrounding the APD 201 in the trench 324, the positions of the centers of adjacent APDs 201 are close to each other. On the other hand, at the vertex portions of the polygonal shape, the positions of the centers of adjacent APDs 201 are farther from each other than at the side portions. That is, when avalanche emission occurs in a certain APD 201, it is considered that the light passing through the side portion of the polygonal shape enters the adjacent APD 201 without being attenuated more than the light passing through the vertex of the polygonal shape. Therefore, by arranging the conductive portions 325 at the side portions of the polygonal shape in the trench 324 and not arranging the conductive portions 325 at the vertices, it is possible to achieve both suppression of crosstalk and suppression of absorption of light obliquely incident on the pixel 101.

[0045] Next, with reference to FIGS. 8(a), 8(b) to FIGS. 11(a), 11(b), the manufacturing process (manufacturing method) of the photoelectric conversion device 100 shown in FIGS. 6(a), 7(a), and 7(b) will be described. First, as shown in FIG. 8(a), semiconductor regions 311 to 317 and 319 are formed in the semiconductor layer 301. For example, semiconductor regions 311 to 315, 317, and 319, which are each diffusion region, may be formed in the semiconductor layer 301 including the semiconductor region 316 as an epitaxial layer having an appropriate impurity concentration of N type by using an ion implantation method or the like.

[0046] Next, as shown in FIG. 8(b), a part of the insulating layer 341, the protective layer 342, and the interlayer insulating layer 343 is formed. For example, silicon oxide or the like is used for the insulating layer 341. The protective layer 342 is provided to prevent plasma damage in subsequent etching processes and contamination caused by the metal used for the contact plug 330, the wiring pattern 331, etc. For example, silicon nitride, silicon oxynitride, silicon carbide, or the like can be used for the protective layer 342. Silicon oxide, silicon nitride, silicon oxynitride, or the like can be used for the interlayer insulating layer 343. The interlayer insulating layer 343 is not limited to inorganic materials depending on the materials used for the contact plug 330 and the wiring pattern 331 formed in subsequent processes, etc., and appropriate materials including organic materials may be used as long as they are suitable.

[0047] After forming a part of the interlayer insulating layer 343, as shown in FIG. 9(a), a trench 324 is formed. For example, first, after forming a mask pattern on the interlayer insulating layer 343, the interlayer insulating layer 343, the protective layer 342, and the insulating layer 341 are etched. Next, the semiconductor layer 301 may be etched. This is because the etching conditions for the materials used for the interlayer insulating layer 343, the protective layer 342, and the insulating layer 341 may be different from those for the silicon used for the semiconductor layer 301. However, it is not limited thereto, and depending on the etching conditions, the etching may be continuously performed from the interlayer insulating layer 343 to the semiconductor layer 301. Also, for example, the trench 324 may be formed before forming the insulating layer 341, the protective layer 342, and the interlayer insulating layer 343, and then the insulating layer 341, the protective layer 342, and the interlayer insulating layer 343 may be formed.

[0048] The trench 324 is etched from the main surface 391 to the main surface 392 of the semiconductor layer 301. The trench 324 may penetrate the semiconductor region 314 as shown in FIG. 9(a), or the bottom of the trench 324 (the end portion on the main surface 392 side of the semiconductor layer 301) may be located in the semiconductor region 314. Also, the bottom of the trench 324 may be located in the semiconductor region 317. The trench 324 is formed such that the conductive portion 325 is formed at least up to the depth at which the semiconductor region 312 is disposed in the depth direction which is the direction connecting the main surface 391 and the main surface 392. As described above, avalanche multiplication is induced in the depletion layer region formed to extend from the semiconductor region 312 to a partial region of the semiconductor region 311. Therefore, avalanche emission occurs in the depletion layer region. This is because crosstalk due to avalanche emission can be suppressed by forming the conductive portion 325 from the main surface 391 of the semiconductor layer 301 to the depth at which the semiconductor region 312 is disposed.

[0049] After forming the trench 324, as shown in FIG. 9(b), the insulator 326 is embedded in the trench 324. The insulator 326 may completely fill the trench 324 or may have voids in part. Silicon oxide, silicon nitride, etc. can be used for the insulator 326. The insulator 326 may be composed of one material such as silicon oxide, for example. Also, for example, considering the formation of the next conductive part 325, the insulator 326 may be composed of a plurality of insulating layers. More specifically, the insulator 326 includes, for example, an insulating layer using silicon oxide, an insulating layer arranged between the insulating layer using silicon oxide and the inner wall of the trench 324, and an insulating layer using, for example, silicon nitride that contains a material different from silicon oxide. By using the insulating layer using silicon nitride as an etch stopper to etch the insulating layer using silicon oxide, a trench for embedding the conductive part 325 can be formed. An insulating layer using silicon oxide may be further arranged between the insulating layer using silicon nitride and the inner wall of the trench 324. By arranging silicon oxide at the interface between the semiconductor layer 301 and the insulator 326, the interface state density is reduced and noise is suppressed compared to the case where silicon nitride is arranged. So far, FIGS. 8(a), 8(b), 9(a), and 9(b) are cross-sections between A-A' shown in FIG. 6(a).

[0050] Next, as shown in FIGS. 10(a) and 10(b), trenches are formed in the insulator 326 in the portion where the conductive part 325 is to be formed. FIG. 10(a) is a cross-section between A-A' shown in FIG. 6(a), and FIG. 10(b) is a cross-section between B-B' shown in FIG. 6(a). In the following steps as well, cross-sections between A-A' and B-B' shown in FIG. 6(a) are shown.

[0051] As described above, since the plurality of conductive parts 325 are arranged separately from each other, trenches are formed in a part of the insulator 326 that fills the trench 324. For example, the portion shown in FIG. 10(a) is protected by a mask pattern, and no trench for embedding the conductive part 325 is formed.

[0052] Also, as shown in Fig. 10(b), in the trench for embedding the conductive portion 325, as described above, a part of the insulating layer of the insulator 326 may remain. For example, when the insulator 326 is composed of silicon oxide (for embedding) / silicon nitride (etch stopper) / silicon oxide (for forming the interface with the semiconductor layer 301), the layer of silicon oxide for forming the interface with the semiconductor layer 301 may remain. In that case, considering that the same potential as the semiconductor region 312 that functions as the anode of the APD 201 is applied to the conductive portion 325, the thickness of the remaining silicon oxide can be about 0.1 μm to 0.15 μm.

[0053] After forming the trench for embedding the conductive portion 325, as shown in Figs. 11(a) and 11(b), the conductive portion 325 is embedded in the trench. As described above, W, Cu, Ag, etc. can be used for the conductive portion 325. Also, barrier metals such as W, Cu, Ag (for example, TiN, tantalum nitride (TaN), AlCu, etc.) may be disposed. Further, in the trench for embedding the conductive portion 325, as described above, when a part of the insulating layer of the insulator 326 remains, the said part of the insulating layer constituting the insulator 326 is disposed between the inner wall of the trench 324 and the conductive portion 325.

[0054] After forming the conductive portion 325 and the insulator 326 in the trench 324, the contact plug 330, the wiring pattern 331, and the remaining part of the interlayer insulating layer 343 are formed, and the photoelectric conversion device 100 shown in Figs. 6(a), 7(a), and 7(b) is formed. Also, although not shown in Figs. 7(a) and 7(b), a color filter, a microlens, etc. may be disposed on the interlayer insulating layer 343.

[0055] Next, with reference to FIGS. 12(a) to 12(c) and FIGS. 13(a) and 13(b), another configuration of the pixel 101 arranged in the photoelectric conversion device 100 of the present embodiment will be described. In the above description, the photoelectric conversion device 100 has a so-called front surface illumination type configuration. On the other hand, the photoelectric conversion device 100 shown in FIGS. 12(a) to 12(c) and FIGS. 13(a) and 13(b) has a so-called back surface illumination type configuration in which light is incident from the main surface 392 of the semiconductor layer 301. Hereinafter, the description will focus on the differences from the above-described front surface illumination type configuration, and the description of the same configuration may be omitted as appropriate. For example, the conductivity type and the relationship of the impurity concentration of the semiconductor regions 311 to 317 and 319 may be the same as those of the front surface illumination type configuration, and thus the description thereof will be omitted here.

[0056] FIGS. 12(a) to 12(c) are plan views showing the configuration of the pixel 101 arranged in the pixel region 12. FIG. 13(a) is a cross-sectional view taken along the line A-A' shown in FIG. 12(a), and FIG. 13(b) is a cross-sectional view taken along the line B-B' shown in FIG. 12(a). FIG. 12(a) shows the plane of the main surface 391 of the semiconductor layer 301 shown in FIGS. 13(a) and 13(b). FIG. 12(b) shows the arrangement of the respective semiconductor regions when orthographically projected from the main surface 392 of the semiconductor layer 301 shown in FIGS. 13(a) and 13(b). Further, FIG. 12(c) shows the outer edge 332A of the pixel 101 of the wiring pattern 331A connected to the semiconductor region 311 that functions as the cathode of the APD 201, and the inner edge 332B of the pixel 101 of the wiring pattern 331B connected to the semiconductor region 312 that functions as the anode of the APD 201.

[0057] As shown in FIG. 12(c), it can be seen that the region between the outer edge 332A of the wiring pattern 331A and the inner edge 332B of the wiring pattern 331B is narrower than in FIG. 6(a) showing the surface-irradiation type photoelectric conversion device 100. In the surface-irradiation type, light enters the semiconductor layer 301 through the region between the outer edge 332A of the wiring pattern 331A and the inner edge 332B of the wiring pattern 331B. Therefore, it is necessary to design the region between the outer edge 332A of the wiring pattern 331A and the inner edge 332B of the wiring pattern 331B to be wide. On the other hand, in the back-irradiation type, the sensitivity of the pixel 101 (APD201) can be improved by reflecting the light that has passed through the semiconductor layer 301 back to the semiconductor layer 301 again. Therefore, the region between the outer edge 332A of the wiring pattern 331A and the inner edge 332B of the wiring pattern 331B is narrower than the configuration of FIG. 6(b) showing the surface-irradiation type photoelectric conversion device 100 so that more light that has passed through the semiconductor layer 301 is reflected.

[0058] Next, referring to FIGS. 13(a) and 13(b), an explanation will be centered on a configuration different from the configurations shown in FIGS. 7(a) and 7(b) described above. The semiconductor layer 301 shown in FIGS. 13(a) and 13(b) is inverted with respect to the semiconductor layer 301 shown in FIGS. 7(a) and 7(b). This is because, similar to FIGS. 7(a) and 7(b), the figure is drawn assuming that light enters from the upper side of the figure.

[0059] In the configuration shown in FIGS. 13(a) and 13(b), the trench 324 includes a portion 324a arranged to extend from the main surface 391 to the main surface 392 of the semiconductor layer 301, and a portion 324b arranged between the portion 324a and the main surface 392 of the semiconductor layer 301. At this time, a step is formed at the connection portion between the portion 324a and the portion 324b of the trench 324. The portion 324a and the portion 324b of the trench 324 will be described using the manufacturing process (manufacturing method) described later.

[0060] Also, in the configuration shown in FIGS. 7(a) and 7(b), a part of the semiconductor region 316 is arranged between the semiconductor region 314 and the main surface 392 of the semiconductor layer 301. On the other hand, in the back-illuminated type photoelectric conversion device 100 shown in FIGS. 13(a) and 13(b), the main surface 392 of the semiconductor layer 301 is constituted by the semiconductor region 314, and the semiconductor layer 301 is thinner than the configuration shown in FIGS. 7(a) and 7(b). Further, in the configuration shown in FIGS. 13(a) and 13(b), a pinning layer 321, a planarization layer 322, and a microlens 323 are arranged on the main surface 392 of the semiconductor layer 301. By arranging the pinning layer 321 in contact with the main surface 392 of the semiconductor layer 301, holes are induced in the vicinity of the main surface 392 of the semiconductor layer 301, and the dark current is suppressed. For the pinning layer 321, hafnium oxide, zirconium oxide, aluminum oxide, titanium oxide, tantalum oxide, etc. can be used. The planarization layer 322 arranged between the pinning layer 321 and the microlens 323 is a layer for flattening the surface on which the microlens 323 is arranged. The planarization layer 322 may be formed of an inorganic material or an organic material such as resin. Further, the planarization layer 322 may have a laminated structure in which a plurality of material layers are laminated. The microlens 323 can be formed using a resin material or the like. A color filter may be arranged between the pinning layer 321 and the planarization layer 322 or between the planarization layer 322 and the microlens 323. Further, the planarization layer 322 may function as a color filter.

[0061] As shown in FIG. 13(b), unlike the configuration shown in FIG. 7(b), the conductive portion 325 is not formed from the main surface 391 of the semiconductor layer 301 to the semiconductor region 314, but is formed to a position beyond the depth at which the semiconductor region 312 is arranged from the main surface 391 of the semiconductor layer 301. As described above, the probability of avalanche emission occurring is high in the depletion layer region formed to extend from the semiconductor region 312 to a part of the semiconductor region 311. Therefore, the conductive portion 325 only needs to be formed from the main surface 391 of the semiconductor layer 301 to at least the depth at which the semiconductor region 312 is arranged.

[0062] As shown in Fig. 12(a), similar to the configuration shown in Fig. 6(a), a plurality of conductive parts 325 are arranged separately from each other. Thereby, as described above, the sensitivity can be improved while suppressing crosstalk, as compared with the case where the APD 201 is surrounded by the conductive parts 325. Further, as shown in Fig. 13(b), the depth at which the conductive parts 325 are arranged is shallower. Thereby, the possibility that the light obliquely incident on the pixel 101 is absorbed by the conductive parts 325 is reduced. Further, as shown in Figs. 13(a) and 13(b), a portion 324b of the trench 324 has a tapered shape in which the width becomes narrower as it goes from the main surface 392 to the main surface 391 of the semiconductor layer 301. Thereby, when the light obliquely incident on the pixel 101 is reflected at the interface between the semiconductor layer 301 and the insulator 326 embedded in the trench 324, the direction in which it goes is likely to be toward the depletion layer region extending from the semiconductor region 312 to the semiconductor region 311. That is, it becomes possible to further improve the sensitivity of the pixel 101 (APD 201) while suppressing crosstalk.

[0063] Next, with reference to Figs. 14(a), 14(b) to Figs. 21(a), 21(b), the manufacturing process (manufacturing method) of the photoelectric conversion device 1 hundred shown in Figs. 12(a), 12(b), Figs. 13(a), 13(b) will be described. The process shown in Fig. 14(a) may be the same as the process shown in Fig. 8(a) described above. As shown in Fig. 14(a), semiconductor regions 311 to 317, 319 are formed in the semiconductor layer 301 by using ion implantation or the like. Next, as shown in Fig. 14(b), a part of the insulating layer 341, the protective layer 342, and the interlayer insulating layer 343 are formed. The process shown in Fig. 14(b) may be the same as the process shown in Fig. 8(b) described above.

[0064] After forming a part of the insulating layer 341, the protective layer 342, and the interlayer insulating layer 343, as shown in FIG. 15(a), a portion 324a of the trench 324 is formed so as to extend from the main surface 391 of the semiconductor layer 301 toward the main surface 392. The portion 324a of the trench 324 is formed to extend at least to a depth at which the conductive portion 325 and at least the semiconductor region 312 are disposed. In other words, the portion 324a of the trench 324 is formed to penetrate the semiconductor region 312 in the depth direction, which is the direction connecting the main surface 391 and the main surface 392 of the semiconductor layer 301. The bottom of the portion 324a of the trench 324 may have a rounded shape as shown in FIG. 15(a) for the process of etching the semiconductor layer 301, which is, for example, silicon.

[0065] After forming the portion 324a of the trench 324, as shown in FIG. 15(b), an insulator 326 is embedded in the portion 324a of the trench 324. The insulator 326 may completely fill the trench 324 or may have a void in part. Further, the insulator 326 may be composed of one material or may be composed of a plurality of insulating layers as described above. So far, FIGS. 14(a), 14(b), FIGS. 15(a), and 15(b) are cross-sections between A-A' shown in FIG. 12(a).

[0066] Next, as shown in FIGS. 16(a) and 16(b), trenches are formed in the insulator 326 in the portion where the conductive portion 325 is to be formed. FIG. 16(a) is a cross-section between A-A' shown in FIG. 12(a), and FIG. 16(b) is a cross-section between B-B' shown in FIG. 12(a). In the following steps as well, the cross-sections between A-A' and B-B' shown in FIG. 12(a) are shown.

[0067] As described above, since the plurality of conductive portions 325 are arranged separately from each other, trenches are formed in a part of the insulator 326 that fills the trench 324. For example, in the portion shown in FIG. 16(a), no trench is formed for embedding the conductive portion 325. Further, as shown in FIG. 16(b), in the trench for embedding the conductive portion 325, a part of the insulator (insulating layer) of the insulator 326 may remain.

[0068] After forming the trench for embedding the conductive portion 325, as shown in FIGS. 17(a) and 17(b), the conductive portion 325 is embedded in the trench. As the conductive portion 325, W, Cu, Ag, or their barrier metals (for example, TiN, TaN, AlCu, etc.) are embedded.

[0069] After forming the conductive portion 325 and the insulator 326 in the trench 324, as shown in FIGS. 18(a) and 18(b), the remaining portions of the contact plug 330, the wiring pattern 331, and the interlayer insulating layer 343 are formed. The steps up to this point can be carried out in the same manner as the steps shown in FIGS. 8(a), 8(b) to FIGS. 11(a), 11(b) above, except that the trench 324 is formed only in a part 324a which is a part of the trench 324.

[0070] Next, as shown in FIGS. 19(a) and 19(b), the semiconductor layer 301 is thinned until the semiconductor region 314 is exposed as the main surface 392 of the semiconductor layer 301. The thinning of the semiconductor layer 301 can be carried out, for example, using a chemical mechanical polishing (CMP) method, an etch-back method, or the like. Before thinning the semiconductor layer 301, the semiconductor layer 301 may be bonded to a support substrate (not shown) via the interlayer insulating layer 343 or the like. Further, the steps from FIGS. 19(a) and 19(b) are drawn with the semiconductor layer 301 inverted with respect to the steps up to FIGS. 18(a) and 18(b).

[0071] After thinning the semiconductor layer 301, as shown in FIGS. 20(a) and 20(b), a portion 324b of the trench 324 is formed. The portion 324b of the trench 324 is etched from the main surface 392 to the main surface 391 of the semiconductor layer 301. As described above, the portion 324b of the trench 324 may be formed to have a tapered shape in which the width narrows as it goes from the main surface 392 to the main surface 391 of the semiconductor layer 301. In that case, at the connection portion between the portion 324a and the portion 324b of the trench 324, the portion 324a and the portion 324b can be designed such that the width of the portion 324a is wider than the width of the portion 324b. Therefore, a step is generated at the connection portion between the portion 324a and the portion 324b of the trench 324. Also, at the connection portion between the portion 324a and the portion 324b of the trench 324, the width of the portion 324a is wider than the width of the portion 324b. Therefore, even when an alignment deviation or the like occurs when forming the portion 324b formed after the portion 324a of the trench 324, the portion 324a and the portion 324b are more likely to be connected to each other.

[0072] Also, when forming the trench 324, a portion 324a etched from the main surface 391 to the main surface 392 of the semiconductor layer 301 and a portion 324b etched from the main surface 392 to the main surface 391 are connected to each other. Therefore, the trench 324 has a structure that penetrates the semiconductor layer 301.

[0073] The portion 324b of the trench 324 does not have to have a tapered shape. Even when the portion 324b of the trench 324 does not have a tapered shape, the portion 324a and the portion 324b may be designed such that the width of the portion 324a is wider than the width of the portion 324b. Thereby, even when an alignment deviation occurs, the portion 324a and the portion 324b are more likely to be connected to each other.

[0074] After forming the portion 324b of the trench 324, as shown in FIGS. 21(a) and 21(b), the insulator 326 is embedded in the portion 324b of the trench 324. The insulator 326 may completely fill the portion 324b of the trench 324, or there may be some voids. Also, the portion of the insulator 326 embedded in the portion 324a of the trench 324 and the portion of the insulator 326 embedded in the portion 324b of the trench 324 may have different configurations. For example, the portion of the insulator 326 embedded in the portion 324a of the trench 324 has the multilayer structure as described above, and the portion of the insulator 326 embedded in the portion 324b of the trench 324 may be composed of a single material.

[0075] Also, the portion of the insulator 326 embedded in the portion 324b of the trench 324 is not limited to the silicon oxide or silicon nitride described above. For example, aluminum oxide or tantalum oxide may be embedded. Further, for example, a resin containing white particles such as titanium oxide may be embedded as the insulator 326. When aluminum oxide is embedded in the portion 324b of the trench 324, the portion of the insulator 326 embedded in the portion 324b of the trench 324 functions in the same manner as the pinning layer 321. Also, when tantalum oxide is embedded as the insulator 326 in the portion 324b of the trench 324, the portion 324b can function as an antireflection film that suppresses stray light between the pixels 101. Also, when a resin containing white particles such as titanium oxide is embedded as the insulator 326 in the portion 324b of the trench 324, the insulator 326 can function as a reflecting member that reflects not only the interface between the semiconductor layer 301 and the insulator 326 but also the light incident on the insulator 326. Not limited to a resin containing white particles such as titanium oxide, a reflecting member using a material having a higher reflectance than the conductive portion 325 may be disposed in the portion 324b of the trench 324. The reflecting member may be, for example, a metal such as aluminum (for example, a metal layer). In that case, the portion of the insulator 326 embedded in the portion 324b of the trench 324 may have a laminated structure of the insulator 326 and the reflecting member.

[0076] After the portion 324b of the trench 324 is embedded with the insulator 326, the pinning layer 321, the planarization layer 322, the microlens 323, etc. are formed, and the photoelectric conversion device 100 shown in FIGS. 13(a), 13(b), 14(a), and 14(b) is formed. In the photoelectric conversion device 100 shown in FIGS. 13(a), 13(b), 14(a), and 14(b), the conductive portion 325 is arranged in the portion 324a of the trench 324 and not in the portion 324b. Thereby, as described above, it is possible to suppress the light obliquely incident on the pixel 101 from being absorbed by the conductive portion 325, and while suppressing crosstalk, further improve the sensitivity of the pixel 101 (APD 201).

[0077] FIGS. 22(a), 22(b), 23(a), and 23(b) are diagrams showing modified examples of the photoelectric conversion device 100 shown in FIGS. 12(a) to 12(c), 13(a), and 13(b). FIGS. 22(a) and 22(b) are plan views showing the configuration of the pixel 101 arranged in the pixel region 12. FIG. 23(a) is a cross-sectional view taken along the line A-A' shown in FIG. 22(a), and FIG. 23(b) is a cross-sectional view taken along the line B-B' shown in FIG. 22(a). FIG. 22(a) shows the plane on the main surface 391 of the semiconductor layer 301 shown in FIGS. 23(a) and 23(b). FIG. 22(b) shows the arrangement of the respective semiconductor regions when orthographically projected from the main surface 392 of the semiconductor layer 301 shown in FIGS. 23(a) and 23(b).

[0078] In the configurations shown in FIGS. 22(a), 22(b), FIGS. 23(a), and 23(b), a plurality of conductive portions 325' are arranged at intervals from each other in the portion 324b of the trench 324. Further, the conductive portion 325 arranged in the portion 324a of the trench 324 is arranged over the entire portion 324a. That is, each APD 201 is continuously surrounded by the conductive portion 325. By surrounding the APD 201 with the conductive portion 325 arranged in the portion 324a of the trench 324, the suppression effect of crosstalk between the pixels 101 due to avalanche emission is further enhanced. Further, since the conductive portion 325' is arranged in the portion 324b of the trench 324, crosstalk due to avalanche emission is more suppressed also in the portion 324b of the trench 324. Since the conductive portions 325' arranged in the portion 324b of the trench 324 are arranged at intervals from each other, improvement in the sensitivity of the pixel 101 (APD 201) is achieved as compared with the case where the conductive portion 325' is arranged so as to surround the APD 201.

[0079] FIGS. 24(a), (b), FIGS. 25(a), (b) are diagrams showing modified examples of the photoelectric conversion device 100 shown in FIGS. 12(a) to 12(c), FIGS. 13(a), (b). FIGS. 24(a), (b) are plan views showing the configuration of the pixel 101 arranged in the pixel region 12. FIG. 25(a) is a cross-sectional view taken along the line A - A' shown in FIG. 24(a), and FIG. 25(b) is a cross-sectional view taken along the line B - B' shown in FIG. 24(a). FIG. 24(a) shows a plane on the main surface 391 of the semiconductor layer 301 shown in FIGS. 25(a), (b). FIG. 24(b) shows the arrangement of the respective semiconductor regions when orthographically projected from the main surface 392 of the semiconductor layer 301 shown in FIGS. 25(a), (b).

[0080] In the configurations shown in FIGS. 22(a), 22(b), FIGS. 23(a), and 23(b), a scattering and diffraction structure 328 is provided on the main surface 392 of the semiconductor layer 301 so as to overlap at least a part of the APD 201. The scattering and diffraction structure 328 is formed by forming a trench in the main surface 392 of the semiconductor layer 301 and embedding an appropriate material in the trench. For example, the trench of the scattering and diffraction structure 328 may be embedded with the same material as the insulator 326 embedded in the portion 324b of the trench 324. For example, the trench of the scattering and diffraction structure 328 may be embedded with silicon oxide or silicon nitride, or may be embedded with an organic material such as resin or metal. The trench of the scattering and diffraction structure 328 can be formed, for example, at a depth of about 0.1 to 0.6 μm from the main surface 392 of the semiconductor layer 301. In order to sufficiently enhance the diffraction of the light incident on the pixel 101, the depth of the trench may be larger than the width of the trench.

[0081] When the scattering and diffraction structure 328 is formed on the main surface 392 of the semiconductor layer 301 where the light is incident, the light incident on the pixel 101 is scattered. As a result, the incident light travels obliquely within the pixel 101, so that an optical path length equal to or greater than the thickness of the semiconductor layer 301 can be ensured, and the photoelectric conversion efficiency is increased. In addition, due to the increase in the optical path length, it becomes possible to photoelectrically convert light of a longer wavelength than in the case where the scattering and diffraction structure 328 is not provided.

[0082] In the diffuse diffraction structure 328, as shown in FIG. 24(b), when polygonal unit structures are periodically arranged, incident light is strongly diffracted in a specific direction. More specifically, in the orthographic projection onto the main surface 392 of the semiconductor layer 301, light incident in a direction orthogonal to each side of the polygonal unit structure of the diffuse diffraction structure 328 is diffracted. Therefore, as shown in FIGS. 24(a) and 24(b), the conductive portion 325 may not be arranged on a virtual line passing through the center of the APD 201 and orthogonal to at least one side of the unit structure of the diffuse diffraction structure 328. In the case of the diffuse diffraction structure 328 shown in FIG. 24(b), the incident light is diffracted in the direction of each vertex of the polygonal trench 324. If the conductive portion 325 is arranged in the direction in which the incident light is diffracted, the diffracted light may be absorbed by the conductive portion 325. Therefore, the conductive portion 325 is not arranged in the region including each vertex of the polygonal trench 324, but is arranged in the side portion of the polygonal trench 324. Thereby, the sensitivity of the pixel 101 (APD 201) can be improved while suppressing crosstalk.

[0083] The shape of the diffuse diffraction structure 328 in the orthographic projection onto the main surface 392 of the semiconductor layer 301 is not limited to a shape that is overall rectangular with rectangular unit structures periodically arranged by rotating the rectangular trench 324 by 45° as shown in FIG. 24(b). As shown in FIG. 26(a), compared to FIG. 24(b), some unit structures may have a shape that protrudes from the overall rectangular shape. Also, for example, as shown in FIG. 26(b), the overall shape may be rectangular in the same rotation direction as the rectangular trench 324. The shapes shown in FIGS. 26(a) and 26(b) have a larger area occupied by the diffuse diffraction structure 328 than the shape shown in FIG. 24(b), and more of the incident light is diffracted, so the sensitivity of the pixel 101 (APD 201) can be further improved.

[0084] Also, the unit structure of the scattering diffraction structure 328 is not limited to being rotated 45° with respect to the rectangular trench 324. As shown in FIGS. 27(a), 27(b), FIGS. 28(a), 28(b), rectangular unit structures in the same rotation direction with respect to the rectangular trench 324 may be periodically arranged to form the scattering diffraction structure 328. Even in that case, as shown in FIGS. 27(a), 27(b), the conductive portion 325 may not be arranged on an imaginary line passing through the center of the APD 201 and orthogonal to at least one side of the unit structure of the scattering diffraction structure 328. For example, the conductive portion 325 may be arranged in a region including each vertex of the polygonal trench 324. That is, in the orthographic projection onto the main surface 392 (main surface 391) of the semiconductor layer 301, the portions of the trench 324 arranged to surround the APDs 201a and 201b respectively have a polygonal shape sharing one vertex, and the conductive portion 325 may be arranged at the shared vertex. Even in this case, in the orthographic projection onto the main surface 391 (main surface 392) of the semiconductor layer 301, the conductive portion 325 may include a portion arranged between the centers of the adjacent APDs 201a and 201b. Also in the configurations shown in FIGS. 27(a), 27(b), FIGS. 28(a), 28(b), the sensitivity of the pixel 101 (APD 201) can be improved by arranging the scattering diffraction structure 328.

[0085] Also, as shown in FIG. 24(a), in the orthographic projection onto the main surface 391 of the semiconductor layer 301, the end portion of the conductive portion 325 may be curved. By making the end portion of the conductive portion 325 have a rounded shape, in other words, by making the end portion of the trench for embedding the conductive portion 325 have a rounded shape, for example, the coverage of the barrier metal arranged on the conductive portion 325 to the trench is improved. Thereby, the stability (for example, the defect rate of the pixel 101, etc.) when manufacturing the photoelectric conversion device 100 is improved. The shape of the end portion of the conductive portion 325 shown in FIG. 24(a) can also be applied to each of the above-described configurations. Also, the other above-described configurations may be appropriately combined. For example, the scattering diffraction structure 328 may be added to the configurations shown in FIGS. 22(a), 22(b), FIGS. 23(a), 23(b).

[0086] Hereinafter, application examples of the photoelectric conversion device 100 in which the above pixel 101 is arranged will be described.

[0087] FIG. 29 is a block diagram showing a schematic configuration of a photoelectric conversion system. The photoelectric conversion device 100 described in each of the above embodiments is applicable to various photoelectric conversion systems. Examples of applicable photoelectric conversion systems include a digital still camera, a digital camcorder, a surveillance camera, a copying machine, a facsimile, a mobile phone, an in-vehicle camera, an observation satellite, and the like. In addition, a camera module including an optical system such as a lens and an imaging device is also included in the photoelectric conversion system. In FIG. 29, a block diagram of a digital still camera is illustrated as an example of these.

[0088] The photoelectric conversion system 1000 illustrated in FIG. 29 includes an imaging device 1004 which is an example of a photoelectric conversion device, a lens 1002 that forms an optical image of a subject on the imaging device 1004, a diaphragm 1003 for variably controlling the amount of light passing through the lens 1002, and a barrier 1001 for protecting the lens 1002. The lens 1002 and the diaphragm 1003 are an optical system (optical device) that condenses light on the imaging device 1004. The imaging device 1004 is the photoelectric conversion device 100 (imaging device) of any of the above embodiments, and converts the optical image formed by the lens 1002 into an electrical signal.

[0089] The photoelectric conversion system 1000 also includes a signal processing unit 1007 which is an image generation unit that generates an image by processing the output signal output by the imaging device 1004. The signal processing unit 1007 functions as a processing device that performs operations such as various corrections and compressions as necessary to output image data. The signal processing unit 1007 may be formed on the semiconductor substrate on which the imaging device 1004 is provided, or may be formed on a semiconductor substrate different from the imaging device 1004. Further, the imaging device 1004 and the signal processing unit 1007 may be formed on the same semiconductor substrate.

[0090] The photoelectric conversion system 1000 further includes a memory unit 1010 for temporarily storing image data and an external interface unit (external I / F unit) 1013 for communicating with an external computer or the like. Furthermore, the photoelectric conversion system 1000 includes a recording medium 1012 such as a semiconductor memory for recording or reading imaging data, and a recording medium control interface unit (recording medium control I / F unit) 1011 for recording or reading from the recording medium 1012. The recording medium control I / F unit 1011 and the recording medium 1012 may form part of a storage device. Note that the recording medium 1012 may be built into the photoelectric conversion system 1000 or may be detachable.

[0091] Furthermore, the photoelectric conversion system 1000 includes an overall control and arithmetic unit 1009 for performing various operations and controlling the entire digital still camera, and a timing generation unit 1008 for outputting various timing signals to the imaging device 1004 and the signal processing unit 1007. The overall control and arithmetic unit 1009 and the timing generation unit 1008 may form part of a control device for controlling the operation of the photoelectric conversion system 1000. Here, the timing signal or the like may be input from the outside, and the photoelectric conversion system 1000 may have at least the imaging device 1004 and the signal processing unit 1007 that processes the output signal output from the imaging device 1004.

[0092] The imaging device 1004 outputs an imaging signal to the signal processing unit 1007. The signal processing unit 1007 performs predetermined signal processing on the imaging signal output from the imaging device 1004 and outputs image data. The signal processing unit 1007 generates an image using the imaging signal. Although not shown in FIG. 29, a display device such as a display for displaying the generated image may be arranged in the photoelectric conversion system 1000. Thus, according to the present embodiment, a photoelectric conversion system 1000 to which the photoelectric conversion device 100 (imaging device) of any of the above embodiments is applied can be realized.

[0093] Figs. 30(a) and 30(b) are diagrams showing the configurations of the photoelectric conversion system 1300 and the moving body 1301. Fig. 30(a) shows an example of a photoelectric conversion system related to an in-vehicle camera. The photoelectric conversion system 1300 includes an imaging device 1310. The imaging device 1310 is the photoelectric conversion device 100 (imaging device) described in any of the above embodiments. The photoelectric conversion system 1300 has an image processing unit 1312 that performs image processing on a plurality of image data acquired by the imaging device 1310. The photoelectric conversion system 1300 also includes a distance acquisition unit 1316 that calculates the distance to an object, and a collision determination unit 1318 that determines whether there is a possibility of collision based on the calculated distance. Here, the distance acquisition unit 1316 may acquire distance information to the object using the Time of Flight (ToF) method, or may acquire distance information using parallax information or the like. That is, the distance information is information related to parallax, defocus amount, distance to the object, and the like. The collision determination unit 1318 may determine the possibility of collision using any of these distance information. The distance acquisition unit 1316 may be realized by dedicatedly designed hardware, or may be realized by a software module. The distance acquisition unit 1316 may also be realized by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like, or may be realized by a combination of these.

[0094] The photoelectric conversion system 1300 is connected to a vehicle information acquisition device 1320 and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. Further, the photoelectric conversion system 1300 is connected to an ECU 1330, which is a control device (control unit) that outputs a control signal for generating a braking force for the vehicle based on the determination result of a collision determination unit 1318. Further, the photoelectric conversion system 1300 is also connected to an alarm device 1340 that issues an alarm to the driver based on the determination result of the collision determination unit 1318. For example, when the collision determination unit 1318 determines that there is a high possibility of a collision, the ECU 1330 controls a drive device (mechanical device) 1360 such as applying brakes, returning the accelerator, and suppressing engine output to perform vehicle control to avoid collisions and reduce damage. The alarm device 1340 warns the user by sounding an alarm such as a sound, displaying alarm information on a screen of a car navigation system, or applying vibration to a seat belt or a steering wheel.

[0095] In the present embodiment, the photoelectric conversion system 1300 images the surroundings of the vehicle (mobile body 1301), for example, the front or the rear. FIG. 30(b) shows the photoelectric conversion system when imaging the front of the vehicle (imaging range 1350). The vehicle information acquisition device 1320 sends an instruction to the photoelectric conversion system 1300 or the imaging device 1310. With such a configuration, the ranging accuracy can be further improved.

[0096] In the above description, an example of control to avoid collision with other vehicles has been described. However, the photoelectric conversion system 1300 is also applicable to control for automatically driving while following other vehicles, control for automatically driving so as not to deviate from the lane, and the like. Further, the photoelectric conversion system 1300 can be applied not only to vehicles such as automobiles but also to moving bodies (moving devices) such as ships, aircraft, or industrial robots. This moving body mainly includes a driving force generation unit that generates a driving force used for the movement of the moving body, and one or both of rotating bodies mainly used for the movement of the moving body. The driving force generation unit can be an engine, a motor, or the like. The rotating body can be a tire, a wheel, a screw of a ship, a propeller of an aircraft, or the like. In addition, the photoelectric conversion system 1300 can be applied not only to moving bodies but also to devices that widely use object recognition, such as an advanced road traffic system (ITS).

[0097] FIG. 31 is a block diagram showing a configuration example of a distance image sensor 1401 which is a photoelectric conversion system. As shown in FIG. 31, the distance image sensor 1401 includes an optical system 1407, a photoelectric conversion device 1408, an image processing circuit 1404, a monitor 1405, and a memory 1406. Then, the distance image sensor 1401 can obtain a distance image corresponding to the distance to the subject by projecting light from a light source device 1409 toward the subject and receiving the light (modulated light or pulsed light) reflected by the surface of the subject.

[0098] The optical system 1407 is configured to have one or a plurality of lenses, guide image light (incident light) from the subject to the photoelectric conversion device 1408, and form an image on the light receiving surface (sensor unit) of the photoelectric conversion device 1408.

[0099] As the photoelectric conversion device 1408, the photoelectric conversion device 100 of each of the above-described embodiments is applied, and a distance signal indicating a distance obtained from the light reception signal output from the photoelectric conversion device 1408 is supplied to the image processing circuit 1404.

[0100] The image processing circuit 1404 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric conversion device 1408. Then, the distance image (image data) obtained by the image processing is supplied to the monitor 1405 for display or supplied to the memory 1406 for storage (recording).

[0101] In the distance image sensor 1401 configured as described above, by applying the photoelectric conversion device 100 described above, it is possible to obtain, for example, a more accurate distance image as the characteristics of the pixels are improved.

[0102] FIG. 32 is a diagram showing an example of a schematic configuration of an endoscopic surgery system 1250 which is a photoelectric conversion system. In FIG. 32, a state in which an operator (doctor) 1231 is performing surgery on a patient 1232 on a patient bed 1233 using the endoscopic surgery system 1250 is illustrated. As shown, the endoscopic surgery system 1250 includes an endoscope 1200, a surgical instrument 1210, and a cart 1234 on which various devices for endoscopic surgery are mounted.

[0103] The endoscope 1200 includes a lens barrel 1201 in which a region of a predetermined length from the tip is inserted into the body cavity of the patient 1232, and a camera head 1202 connected to the proximal end of the lens barrel 1201. In the illustrated example, an endoscope 1200 configured as a so-called rigid endoscope having a rigid lens barrel 1201 is illustrated, but the endoscope 1200 may be configured as a so-called flexible endoscope having a flexible lens barrel.

[0104] An opening in which an objective lens is fitted is provided at the tip of the lens barrel 1201. A light source device 1203 is connected to the endoscope 1200, and the 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 1201 and irradiated toward the observation target in the body cavity of the patient 1232 through the objective lens. Note that the endoscope 1200 may be a forward-viewing endoscope, a side-viewing endoscope, or a oblique-viewing endoscope.

[0105] Inside the camera head 1202, an optical system and a photoelectric conversion device are provided, and the reflected light (observation light) from the observation target is condensed by the optical system onto the photoelectric conversion device. The observation light is photoelectrically converted by the photoelectric conversion device, and an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image, is generated. As the photoelectric conversion device, the photoelectric conversion device 100 (imaging device) described in each of the above embodiments can be used. The image signal is transmitted as RAW data to a camera control unit (CCU) 1235.

[0106] The CCU 1235 is composed of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 1200 and the display device 1236. Further, the CCU 1235 receives an image signal from the camera head 1202, and performs various image processes for displaying an image based on the image signal, such as development processing (demosaicing processing), on the image signal.

[0107] The display device 1236 displays an image based on the image signal on which image processing has been performed by the CCU 1235 under the control of the CCU 1235.

[0108] The light source device 1203 is composed of a light source such as an LED (Light Emitting Diode), and supplies irradiation light for photographing the surgical site etc. to the endoscope 1200.

[0109] The input device 1237 is an input interface for the endoscope surgical system 1250. The user can input various information and give instructions to the endoscope surgical system 1250 via the input device 1237.

[0110] The treatment tool control device 1238 controls the drive of the energy treatment tool 1212 for tissue cauterization, incision, or blood vessel sealing etc.

[0111] The light source device 1203 that supplies irradiation light for photographing the surgical site with the endoscope 1200 can be composed of, for example, an LED, a laser light source, or a white light source composed of a combination thereof. When a white light source is composed of a combination of RGB laser light sources, since the output intensity and output timing of each color (each wavelength) can be controlled with high precision, the white balance of the captured image can be adjusted in the light source device 1203. Further, in this case, the laser light from each of the RGB laser light sources is irradiated to the observation target in a time-division manner, and by controlling the driving of the imaging element of the camera head 1202 in synchronization with the irradiation timing, it is also possible to capture images corresponding to each of RGB in a time-division manner. According to this method, a color image can be obtained without providing a color filter on the imaging element.

[0112] Further, the driving of the light source device 1203 may be controlled so as to change the intensity of the output light at predetermined time intervals. By controlling the driving of the imaging element of the camera head 1202 in synchronization with the timing of the change in the intensity of the light, and acquiring images in a time-division manner and synthesizing the images, it is possible to generate a high-dynamic-range image without so-called black crush and white clip.

[0113] Further, the light source device 1203 may be configured to be able to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, the wavelength dependence of light absorption in body tissues is utilized. Specifically, by irradiating light with a narrower band than the irradiation light (i.e., white light) during normal observation, a predetermined tissue such as blood vessels in the mucosal surface layer can be photographed with high contrast. Alternatively, in special light observation, fluorescence observation may be performed to obtain an image using fluorescence generated by irradiating excitation light. In fluorescence observation, it is possible to irradiate excitation light to body tissues and observe the fluorescence from the body tissues, or to locally inject a reagent such as indocyanine green (ICG) into body tissues and irradiate the body tissues with excitation light corresponding to the fluorescence wavelength of the reagent to obtain a fluorescence image. The light source device 1203 can be configured to be able to supply such narrow-band light and / or excitation light corresponding to special light observation.

[0114] Figures 33(a) and 33(b) illustrate glasses 1600 (smart glasses), which are a photoelectric conversion system. The glasses 1600 shown in Figure 33(a) include a photoelectric conversion device 1602. The photoelectric conversion device 1602 is the photoelectric conversion device 100 (imaging device) described in each of the above embodiments. Also, a display device including a light-emitting device such as an OLED or an LED may be provided on the back side of the lens 1601. The photoelectric conversion device 1602 may be one or a plurality. Also, a plurality of types of photoelectric conversion devices may be combined and used. The arrangement position of the photoelectric conversion device 1602 is not limited to that shown in Figure 33(a).

[0115] The glasses 1600 further include a control device 1603. The control device 1603 functions as a power supply that supplies power to the photoelectric conversion device 1602 and the above display device. Also, the control device 1603 controls the operations of the photoelectric conversion device 1602 and the display device. An optical system for condensing light onto the photoelectric conversion device 1602 is formed in the lens 1601.

[0116] Figure 33(b) illustrates glasses 1610 (smart glasses) according to one application example. The glasses 1610 have a control device 1612, and a photoelectric conversion device corresponding to the photoelectric conversion device 1602 and a display device are mounted on the control device 1612. An optical system for projecting the light emitted from the photoelectric conversion device and the display device within the control device 1612 is formed in the lens 1611, and an image is projected onto the lens 1611. The control device 1612 functions as a power supply that supplies power to the photoelectric conversion device and the display device, and controls the operations of the photoelectric conversion device and the display device. The control device may have a line-of-sight detection unit that detects the line of sight of the wearer. The line of sight may be detected using infrared rays. The infrared light-emitting unit emits infrared light to the eyeball of the user who is gazing at the display image. An imaging image of the eyeball is obtained by the imaging unit having a light-receiving element detecting the reflected light of the emitted infrared light from the eyeball. By having a reducing means for reducing the light from the infrared light-emitting unit to the display unit in a plan view, a reduction in image quality is reduced.

[0117] The user's line of sight with respect to the display image is detected from the captured image of the eyeball obtained by infrared imaging. Any known method can be applied to the line-of-sight detection using the captured image of the eyeball. As an example, a line-of-sight detection method based on the Purkinje image due to the reflection of the irradiation light on the cornea can be used.

[0118] More specifically, a line-of-sight detection process based on the pupillary corneal reflex method is performed. Using the pupillary corneal reflex method, a line-of-sight vector representing the orientation (rotation angle) of the eyeball is calculated based on the image of the pupil and the Purkinje image included in the captured image of the eyeball, thereby detecting the user's line of sight.

[0119] The display device of the present embodiment may include a photoelectric conversion device having a light receiving element, and control the display image of the display device based on the user's line-of-sight information from the photoelectric conversion device.

[0120] Specifically, the display device determines, based on the line-of-sight information, a first visual field area that the user is gazing at and a second visual field area other than the first visual field area. The first visual field area and the second visual field area may be determined by the control device of the display device, or the display device may receive those determined by an external control device. In the display area of the display device, the display resolution of the first visual field area may be controlled to be higher than that of the second visual field area. That is, the resolution of the second visual field area may be made lower than that of the first visual field area.

[0121] Also, the display area has a first display area and a second display area different from the first display area, and based on the line-of-sight information, an area with a higher priority may be determined from the first display area and the second display area. The first visual field area and the second visual field area may be determined by the control device of the display device, or the display device may receive those determined by an external control device. The resolution of the area with a higher priority may be controlled to be higher than that of the area other than the area with a higher priority. That is, the resolution of the area with a relatively lower priority may be made lower.

[0122] In addition, AI may be used to determine the first visual field area or the area with high priority. The AI may be a model configured to estimate the angle of the line of sight and the distance to the object at the tip of the line of sight from the eye image, using the eye image and the direction in which the eye in the image is actually looking as teacher data. The AI program may be provided in the display device, the photoelectric conversion device, or an external device. When provided in the external device, it is transmitted to the display device via communication.

[0123] When performing display control based on visual recognition detection, it can be preferably applied to smart glasses further having a photoelectric conversion device for imaging the outside. The smart glasses can display the captured external information in real time.

[0124] The disclosure of this specification includes the following photoelectric conversion device, photoelectric conversion system, mobile body, and device.

[0125] (Item 1) A photoelectric conversion device including a semiconductor layer having a first main surface and a second main surface, and a first avalanche photodiode and a second avalanche photodiode adjacent to each other, and a trench extending from the first main surface toward the second main surface, At least a part of the trench is disposed between the first avalanche photodiode and the second avalanche photodiode, A first conductive portion and a second conductive portion are disposed in the trench, A photoelectric conversion device, wherein in a orthographic projection onto the first main surface, the first conductive portion and the second conductive portion are spaced apart from each other.

[0126] (Item 2) Each of the first avalanche photodiode and the second avalanche photodiode includes a first semiconductor region of a first conductivity type disposed between the first main surface and the second main surface, and a second semiconductor region of a second conductivity type disposed between the first semiconductor region and the second main surface and inducing avalanche multiplication with the first semiconductor region. The photoelectric conversion device according to Item 1, characterized in that it includes the second semiconductor region.

[0127] (Item 3) In the depth direction, which is the direction connecting the first main surface and the second main surface, the first conductive portion and the second conductive portion are arranged at least at the depth where the second semiconductor region is arranged. The photoelectric conversion device according to Item 2, characterized in that.

[0128] (Item 4) In the trench, an insulator is arranged between the first conductive portion and the second conductive portion. The photoelectric conversion device according to any one of Items 1 to 3, characterized in that.

[0129] (Item 5) The insulator includes a first insulating layer and a second insulating layer arranged between the first insulating layer and the inner wall of the trench and containing a material different from that of the first insulating layer. The photoelectric conversion device according to Item 4, characterized in that.

[0130] (Item 6) The second insulating layer is arranged between the inner wall of the trench and the first conductive portion and between the inner wall of the trench and the second conductive portion. The photoelectric conversion device according to Item 5, characterized in that.

[0131] (Item 7) The trench includes a portion arranged so as to surround the first avalanche photodiode and a portion arranged so as to surround the second avalanche photodiode. The photoelectric conversion device according to any one of Items 1 to 6, characterized in that.

[0132] (Item 8) In the orthographic projection onto the first main surface, the first conductive portion includes a portion arranged between the center of the first avalanche photodiode and the center of the second avalanche photodiode. The photoelectric conversion device according to any one of Items 1 to 7, characterized in that.

[0133] (Item 9) In the orthographic projection onto the first main surface, The trench includes a polygonal first portion arranged to surround the first avalanche photodiode and a polygonal second portion arranged to surround the second avalanche photodiode, the first portion and the second portion share one side, the first conductive portion is arranged on the one side, The photoelectric conversion device according to item 8, wherein the second conductive portion is not arranged on the one side.

[0134] (Item 10) In the orthographic projection onto the first main surface, the trench includes a polygonal first portion arranged to surround the first avalanche photodiode and a polygonal second portion arranged to surround the second avalanche photodiode, the first portion and the second portion share one vertex, The photoelectric conversion device according to item 8, wherein the first conductive portion includes a portion arranged at the one vertex.

[0135] (Item 11) The semiconductor layer further includes a third avalanche photodiode arranged adjacent to the first avalanche photodiode via the trench, The photoelectric conversion device according to any one of items 8 to 10, wherein the second conductive portion includes a portion arranged between the center of the first avalanche photodiode and the center of the third avalanche photodiode.

[0136] (Item 12) The photoelectric conversion device according to any one of items 1 to 11, wherein a common potential is supplied to the first conductive portion and the second conductive portion.

[0137] (Item 13) The photoelectric conversion device according to any one of Items 1 to 12, wherein in the orthographic projection onto the first main surface, the ends of the first conductive portion and the second conductive portion are curved.

[0138] (Item 14) The photoelectric conversion device according to any one of Items 1 to 13, wherein light is configured to be incident from the second main surface.

[0139] (Item 15) The trench includes a first portion arranged from the first main surface toward the second main surface and a second portion arranged between the first portion and the second main surface. The photoelectric conversion device according to Item 14, wherein a step is formed at a connection portion between the first portion and the second portion.

[0140] (Item 16) The second portion has a tapered shape in which the width becomes narrower as it goes from the second main surface toward the first main surface. The photoelectric conversion device according to Item 15, wherein at the connection portion, the width of the first portion is wider than the width of the second portion.

[0141] (Item 17) The photoelectric conversion device according to Item 15 or 16, wherein the first conductive portion and the second conductive portion are arranged in the first portion.

[0142] (Item 18) The photoelectric conversion device according to any one of Items 15 to 17, wherein the first conductive portion and the second conductive portion are not arranged in the second portion.

[0143] (Item 19) The photoelectric conversion device according to any one of Items 15 to 18, wherein a reflecting member is arranged in the second portion.

[0144] (Item 20) The photoelectric conversion device according to item 15 or 16, wherein the first conductive part and the second conductive part are arranged in the second part.

[0145] (Item 21) The photoelectric conversion device according to item 20, wherein a third conductive part is arranged over the entire first part.

[0146] (Item 22) The photoelectric conversion device according to any one of items 15 to 21, wherein the trench penetrates the semiconductor layer.

[0147] (Item 23) The photoelectric conversion device according to any one of items 15 to 22, wherein a scattering diffraction structure is provided on the second main surface so as to at least partially overlap with the first avalanche photodiode.

[0148] (Item 24) In the orthographic projection onto the second main surface, the scattering diffraction structure has a polygonal unit structure arranged periodically, The photoelectric conversion device according to item 23, wherein the first conductive part and the second conductive part are not arranged on an imaginary line passing through the center of the first avalanche photodiode and orthogonal to at least one side of the unit structure.

[0149] (Item 25) A photoelectric conversion system comprising: the photoelectric conversion device according to any one of items 1 to 24; a signal processing unit that generates an image using a signal output by the photoelectric conversion device; and is characterized by comprising.

[0150] (Item 26) A moving body comprising the photoelectric conversion device according to any one of items 1 to 24, and having a control unit that controls the movement of the moving body using a signal output by the photoelectric conversion device.

[0151] (Item 27) An apparatus comprising the photoelectric conversion device according to any one of Items 1 to 24, an optical device corresponding to the photoelectric conversion device, a control device for controlling the photoelectric conversion device, a processing device for processing a signal output from the photoelectric conversion device, a display device for displaying information obtained by the photoelectric conversion device, a storage device for storing information obtained by the photoelectric conversion device, and a mechanical device that operates based on the information obtained by the photoelectric conversion device, characterized in that it further comprises at least any one of them.

[0152] The invention is not limited to the above embodiments, and various changes and modifications are possible without departing from the spirit and scope of the invention. Therefore, claims are attached to disclose the scope of the invention.

Explanation of Reference Numerals

[0153] 100: Photoelectric conversion device, 201: Avalanche photodiode, 301: Semiconductor layer, 324: Trench, 325: Conductive portion, 391, 392: Main surface

Claims

1. A photoelectric conversion device comprising a semiconductor layer having a first main surface and a second main surface, and a first avalanche photodiode and a second avalanche photodiode adjacent to each other, and a trench extending from the first main surface toward the second main surface, wherein at least a part of the trench is disposed between the first avalanche photodiode and the second avalanche photodiode, wherein a first conductive portion and a second conductive portion are disposed in the trench, and wherein, in a normal projection onto the first main surface, the first conductive portion and the second conductive portion are spaced apart from each other.

2. Each of the first avalanche photodiode and the second avalanche photodiode includes a first semiconductor region of a first conductivity type disposed between the first main surface and the second main surface, and a second semiconductor region of a second conductivity type disposed between the first semiconductor region and the second main surface and inducing avalanche multiplication with the first semiconductor region. The photoelectric conversion device according to claim 1, characterized in that it comprises:

3. In a depth direction which is a direction connecting the first main surface and the second main surface, the first conductive portion and the second conductive portion are disposed at least at a depth where the second semiconductor region is disposed. The photoelectric conversion device according to claim 2, characterized in that it comprises:

4. In the trench, an insulator is disposed between the first conductive portion and the second conductive portion. The photoelectric conversion device according to claim 1, characterized in that it comprises:

5. The insulator includes a first insulating layer and a second insulating layer disposed between the first insulating layer and the inner wall of the trench and including a material different from that of the first insulating layer. The photoelectric conversion device according to claim 4, characterized in that it comprises:

6. The second insulating layer is disposed between the inner wall of the trench and the first conductive portion and between the inner wall of the trench and the second conductive portion. The photoelectric conversion device according to claim 5, characterized in that it comprises:

7. The trench includes a portion disposed so as to surround the first avalanche photodiode and a portion disposed so as to surround the second avalanche photodiode. The photoelectric conversion device according to claim 1, characterized in that it comprises:

8. In the orthographic projection onto the first main surface, the first conductive portion includes a portion disposed between the center of the first avalanche photodiode and the center of the second avalanche photodiode. The photoelectric conversion device according to claim 1, characterized in that.

9. In the orthographic projection onto the first main surface, The trench includes a polygonal first portion arranged to surround the first avalanche photodiode and a polygonal second portion arranged to surround the second avalanche photodiode. The first portion and the second portion share one side. The first conductive portion is disposed on the one side. The second conductive portion is not disposed on the one side. The photoelectric conversion device according to claim 8, characterized in that.

10. In the orthographic projection onto the first main surface, The trench includes a polygonal first portion arranged to surround the first avalanche photodiode and a polygonal second portion arranged to surround the second avalanche photodiode. The first portion and the second portion share one vertex. The first conductive portion includes a portion disposed at the one vertex. The photoelectric conversion device according to claim 8, characterized in that.

11. The semiconductor layer further includes a third avalanche photodiode arranged adjacent to the first avalanche photodiode via the trench. The second conductive portion includes a portion disposed between the center of the first avalanche photodiode and the center of the third avalanche photodiode. The photoelectric conversion device according to claim 8, characterized in that.

12. A common potential is supplied to the first conductive portion and the second conductive portion. The photoelectric conversion device according to claim 1, characterized in that.

13. In the orthographic projection onto the first main surface, the ends of the first conductive portion and the second conductive portion are curved. The photoelectric conversion device according to claim 1, characterized in that.

14. The photoelectric conversion device according to claim 1, characterized in that light is configured to be incident from the second main surface.

15. The trench includes a first portion arranged from the first main surface toward the second main surface and a second portion arranged between the first portion and the second main surface. The photoelectric conversion device according to claim 14, wherein a step is formed at a connection portion between the first portion and the second portion.

16. The second portion has a tapered shape in which the width becomes narrower as it goes from the second main surface toward the first main surface. The photoelectric conversion device according to claim 15, wherein at the connection portion, the width of the first portion is wider than the width of the second portion.

17. The photoelectric conversion device according to claim 15, wherein the first conductive portion and the second conductive portion are arranged in the first portion.

18. The photoelectric conversion device according to claim 15, wherein the first conductive portion and the second conductive portion are not arranged in the second portion.

19. The photoelectric conversion device according to claim 15, wherein a reflection member is arranged in the second portion.

20. The photoelectric conversion device according to claim 15, wherein the first conductive portion and the second conductive portion are arranged in the second portion.

21. The photoelectric conversion device according to claim 20, wherein a third conductive portion is arranged over the entire first portion.

22. The photoelectric conversion device according to claim 15, wherein the trench penetrates the semiconductor layer.

23. The photoelectric conversion device according to claim 15, wherein a scattering and diffraction structure is provided on the second main surface so as to at least partially overlap the first avalanche photodiode.

24. In a normal projection onto the second main surface, the scattering and diffraction structure has a polygonal unit structure arranged periodically, The photoelectric conversion device according to claim 23, wherein the first conductive portion and the second conductive portion are not arranged on a virtual line passing through the center of the first avalanche photodiode and orthogonal to at least one side of the unit structure.

25. A photoelectric conversion device according to any one of claims 1 to 24, a signal processing unit that generates an image using a signal output from the photoelectric conversion device, A photoelectric conversion system comprising the same.

26. A moving body comprising the photoelectric conversion device according to any one of claims 1 to 24, The moving body having a control unit that controls the movement of the moving body using a signal output from the photoelectric conversion device.

27. An apparatus comprising the photoelectric conversion device according to any one of claims 1 to 24, an optical device corresponding to the photoelectric conversion device, A control device for controlling the photoelectric conversion device, A processing device for processing a signal output from the photoelectric conversion device, A display device for displaying information obtained by the photoelectric conversion device, A storage device for storing information obtained by the photoelectric conversion device, and A device characterized by further comprising at least any one of a mechanical device that operates based on information obtained by the photoelectric conversion device.

Images