Photoelectric conversion device and photodetection system

Abstract

To provide a technique that can effectively increase the light receiving sensitivity of a photoelectric conversion device.SOLUTION: A photoelectric conversion device has a semiconductor layer that is provided with an avalanche photodiode, and a wiring structure layer that is provided on a first surface of the semiconductor layer. The wiring structure layer is formed of metallic material, and has a wiring structure that overlaps with an avalanche multiplication area of the avalanche photodiode in plan view. The wiring structure has first wiring, second wiring that is arranged separated from the first surface compared with the first wiring, and contact electrodes that electrically connect the first wiring and the second wiring with each other. A portion of the first wiring overlapping with the avalanche multiplication area in plan view is provided with openings. The second wiring is arranged to overlap with the entirety of the openings in plan view. The contact electrodes are arranged on the periphery of the openings in plan view.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a photoelectric conversion device and a photodetection system. [Background technology]

[0002] The Single Photon Avalanche Diode (SPAD) is known as a detector capable of detecting weak light at the single photon level. SPADs amplify the signal charge excited by photons by several to several million times by using the avalanche multiplication phenomenon that occurs due to a strong electric field induced at the pn junction of a semiconductor. The current generated by the avalanche multiplication phenomenon is converted into a pulse signal, and the number of pulse signals is counted, making it possible to directly measure the number of incident photons. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-088488 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses a sensor chip that uses metal wiring as a reflective member to reflect light that has passed through a SPAD element back into the SPAD element. However, simply reflecting the light that has passed through the SPAD element does not necessarily improve sensitivity sufficiently. This phenomenon is particularly noticeable in the case of SPAD elements that detect light with longer wavelengths, such as wavelengths in the near-infrared region.

[0005] An object of the present invention is to provide a technique that can effectively improve the light-receiving sensitivity in a photoelectric conversion device and a photodetection system. [Means for solving the problem]

[0006] According to one disclosure of the present specification, a semiconductor device includes a semiconductor layer in which an avalanche photodiode is provided, and a wiring structure layer provided on a first surface side of the semiconductor layer, the wiring structure layer being made of a metal material and having a wiring structure that overlaps an avalanche multiplication region of the avalanche photodiode in a plan view, the wiring structure including a first wiring, a second wiring disposed farther away from the first surface than the first wiring, and electrically connecting the first wiring and the second wiring. Multiple a contact electrode, the first wiring and the second wiring being included in adjacent wiring layers, Multiple a contact electrode contacting the first wiring and the second wiring, an opening being provided in a portion of the first wiring that overlaps with the avalanche multiplication region in a plan view, and the second wiring being arranged to overlap the entire opening in a plan view; Multiple The contact electrode is formed by the opening in a plan view. Surrounding A photoelectric conversion device is provided. Furthermore, according to another disclosure of the present specification, there is provided a photoelectric conversion device comprising: a semiconductor layer in which an avalanche photodiode is provided; and a wiring structure layer provided on a first surface side of the semiconductor layer; the wiring structure layer is made of a metal material and has a wiring structure that overlaps an avalanche multiplication region of the avalanche photodiode in a planar view; the wiring structure has a first wiring, a second wiring that is arranged farther away from the first surface than the first wiring, and a contact electrode that electrically connects the first wiring and the second wiring; the first wiring and the second wiring are included in adjacent wiring layers; the contact electrode is in contact with the first wiring and the second wiring; an opening is provided in a portion of the first wiring that overlaps the avalanche multiplication region in a planar view; the second wiring is arranged to overlap the entire opening in a planar view; and the contact electrode is a frame-shaped structure that surrounds the opening. [Effects of the Invention]

[0007] According to the present invention, it is possible to effectively improve the light-receiving sensitivity in a photoelectric conversion device and a photodetection system. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram (part 1) showing a schematic configuration of a photoelectric conversion device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram (part 2) showing a schematic configuration of the photoelectric conversion device according to the first embodiment of the present invention. [Figure 3] 1 is a block diagram showing an example of the configuration of a pixel of a photoelectric conversion device according to a first embodiment of the present invention. [Figure 4] 1 is a perspective view showing an example of the configuration of a photoelectric conversion device according to a first embodiment of the present invention. [Figure 5] FIG. 2 is a diagram illustrating the basic operation of a photoelectric conversion unit in the photoelectric conversion device according to the first embodiment of the present invention. [Figure 6] 1 is a cross-sectional view showing the structure of a photon detecting element in a photoelectric conversion device according to a first embodiment of the present invention. [Figure 7] 1 is a plan view showing the structure of a photon detecting element in a photoelectric conversion device according to a first embodiment of the present invention. [Figure 8] FIG. 5 is a cross-sectional view showing the structure of a photon detecting element in a photoelectric conversion device according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a plan view showing the structure of a photon detecting element in a photoelectric conversion device according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a plan view (part 1) showing the structure of a photon detecting element in a photoelectric conversion device according to a fourth embodiment of the present invention. [Figure 11] FIG. 10 is a plan view (part 2) showing the structure of a photon detecting element in a photoelectric conversion device according to a fourth embodiment of the present invention. [Figure 12] FIG. 10 is a block diagram showing a schematic configuration of a light detection system according to a fifth embodiment of the present invention. [Figure 13] FIG. 10 is a block diagram showing a schematic configuration of a light detection system according to a sixth embodiment of the present invention. [Figure 14] FIG. 13 is a schematic diagram showing an example of the configuration of a light detection system according to a seventh embodiment of the present invention. [Figure 15] FIG. 13 is a schematic diagram showing an example of the configuration of a moving body according to an eighth embodiment of the present invention. [Figure 16] FIG. 13 is a block diagram showing a schematic configuration of a light detection system according to an eighth embodiment of the present invention. [Figure 17] FIG. 13 is a flowchart showing the operation of the light detection system according to the eighth embodiment of the present invention. [Figure 18] FIG. 13 is a schematic diagram showing a schematic configuration of a light detection system according to a ninth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The embodiments described below are intended to embody the technical concept of the present invention and are not intended to limit the scope of the present invention. The sizes and positional relationships of the components shown in the drawings may be exaggerated for clarity.

[0010] [First embodiment] The structure of a photoelectric conversion device according to a first embodiment of the present invention will be described with reference to Figs. 1 to 4. Figs. 1 and 2 are block diagrams showing a schematic configuration of a photoelectric conversion device according to this embodiment. Fig. 3 is a block diagram showing an example configuration of a pixel of a photoelectric conversion device according to this embodiment. Fig. 4 is a perspective view showing an example configuration of a photoelectric conversion device according to this embodiment.

[0011] As shown in FIG. 1, the photoelectric conversion device 100 according to this embodiment includes a pixel section 10, a vertical scanning circuit section 40, a readout circuit section 50, a horizontal scanning circuit section 60, an output circuit section 70, and a control pulse generation section 80.

[0012] The pixel unit 10 includes a plurality of pixels 12 arranged in an array of a plurality of rows and a plurality of columns. As described below, each pixel 12 may be composed of a photoelectric conversion unit including a photon detection element and a pixel signal processing unit that processes a signal output from the photoelectric conversion unit. The number of pixels 12 constituting the pixel unit 10 is not particularly limited. For example, the pixel unit 10 may be composed of a plurality of pixels 12 arranged in an array of several thousand rows and several thousand columns, as in a general digital camera. Alternatively, the pixel unit 10 may be composed of a plurality of pixels 12 arranged in a single row or a single column. Alternatively, the pixel unit 10 may be composed of a single pixel 12.

[0013] A control line 14 is arranged in each row of the pixel array of the pixel unit 10, extending in a first direction (the horizontal direction in FIG. 1 ). The control line 14 is connected to each of the pixels 12 aligned in the first direction and serves as a signal line common to these pixels 12. The first direction in which the control lines 14 extend may be referred to as the row direction or horizontal direction. Each of the control lines 14 may include multiple signal lines for supplying multiple types of control signals to the pixels 12. The control lines 14 in each row are connected to a vertical scanning circuit unit 40.

[0014] Furthermore, data lines 16 are arranged in each row of the pixel array of the pixel unit 10, extending in a first direction. The data lines 16 are connected to the pixels 12 aligned in the first direction, respectively, and serve as signal lines common to these pixels 12. Each of the data lines 16 may include a plurality of signal lines for transferring multi-bit digital signals output from the pixels 12, one bit at a time. The data lines 16 in each row are connected to a readout circuit unit 50.

[0015] In each column of the pixel array of the pixel unit 10, a control line 18 is arranged, extending in a second direction (vertical direction in FIG. 1 ) intersecting the first direction. The control line 18 is connected to each of the pixels 12 aligned in the second direction and serves as a signal line common to these pixels 12. The second direction in which the control lines 18 extend may be referred to as the column direction or vertical direction. Each of the control lines 18 may include multiple signal lines for supplying multiple types of control signals to the pixels 12. The control lines 18 in each row are connected to a horizontal scanning circuit unit 60.

[0016] The vertical scanning circuit unit 40 is a control unit that receives control signals output from the control pulse generation unit 80, generates control signals for driving the pixels 12, and supplies the control signals to the pixels 12 via control lines 14. The vertical scanning circuit unit 40 may include logic circuits such as a shift register and an address decoder. The vertical scanning circuit unit 40 sequentially supplies control signals to the pixels 12 of the pixel unit 10 row by row, and sequentially drives the pixels 12 of the pixel unit 10 row by row.

[0017] The horizontal scanning circuit unit 60 is a control unit that receives control signals output from the control pulse generation unit 80, generates control signals for driving the pixels 12, and supplies the control signals to the pixels 12 via control lines 18. The horizontal scanning circuit unit 60 may use logic circuits such as a shift register and an address decoder. The horizontal scanning circuit unit 60 sequentially scans the pixels 12 in the pixel unit 10 column by column, and outputs pixel signals held by each pixel 12 to the readout circuit unit 50 via data lines 16.

[0018] The readout circuit unit 50 is provided corresponding to each row of the pixel array of the pixel unit 10. A plurality of decision circuits and The readout circuit unit 50 has a plurality of holding units (not shown). The readout circuit unit 50 has a function of holding, in the holding unit for the corresponding column, pixel signals of the pixels 12 in each column that are output row by row from the pixel unit 10 via the data lines 16. The readout circuit unit 50 receives a control signal supplied from the control pulse generation unit 80, and sequentially outputs the pixel signals held in the holding units for each row to the output circuit unit 70.

[0019] The output circuit unit 70 has an external interface circuit and is a circuit unit for outputting the pixel signals output from the readout circuit unit 50 to the outside of the photoelectric conversion device 100. The external interface circuit included in the output circuit unit 70 is not particularly limited. For example, a SerDes (SERializer / DESerializer) transmission circuit such as an LVDS (Low Voltage Differential Signaling) circuit or an SLVS (Scalable Low Voltage Signaling) circuit can be used as the external interface circuit.

[0020] The control pulse generation unit 80 is a control circuit that generates control signals for controlling the operation and timing of the vertical scanning circuit unit 40, the readout circuit unit 50, and the horizontal scanning circuit unit 60, and supplies these to each functional block. Note that at least some of the control signals for controlling the operation and timing of the vertical scanning circuit unit 40, the readout circuit unit 50, and the horizontal scanning circuit unit 60 may be supplied from outside the photoelectric conversion device 100.

[0021] The connection of the functional blocks of the photoelectric conversion device 100 is not limited to the example configuration shown in FIG. 1, and may be configured as shown in FIG. 2, for example.

[0022] 2, a data line 16 extending in the second direction is arranged in each column of the pixel array of the pixel unit 10. The data line 16 is connected to each of the pixels 12 aligned in the second direction and serves as a common signal line for these pixels 12. The data line 16 in each column is connected to a readout circuit unit 50.

[0023] Reading The readout circuit unit 50 is a receiving circuit that receives pixel signals output via the data lines 16, and has the function of holding the pixel signals of the pixels 12 in each column that are output row by row from the pixel unit 10 via the data lines 16 in the holding unit of the corresponding row. The readout circuit section 50 has a plurality of determination circuits and a plurality of holding sections (not shown) provided corresponding to each column of the pixel array of the pixel section 10.

[0024] The horizontal scanning circuit unit 60 receives a control signal output from the control pulse generation unit 80, generates a control signal for reading out pixel signals from the holding units of each column of the readout circuit unit 50, and supplies the control signal to the readout circuit unit 50. The horizontal scanning circuit unit 60 sequentially scans the holding units of each column of the readout circuit unit 50, and sequentially outputs the pixel signals held in each to the output circuit unit 70. Other functional blocks in the configuration example of FIG. 2 may be similar to those in the configuration example of FIG.

[0025] 3, each pixel 12 has a photoelectric conversion unit 20 and a pixel signal processing unit 30. The photoelectric conversion unit 20 has a photon detection element 22 and a quenching element 24. The pixel signal processing unit 30 has a waveform shaping circuit 32, a processing circuit 34, and a pixel output circuit 36.

[0026] The photon detecting element 22 may be an avalanche photodiode (hereinafter referred to as "APD"). The anode of the APD constituting the photon detecting element 22 is connected to a node to which a voltage VL is supplied. The cathode of the APD constituting the photon detecting element 22 is connected to one terminal of the quench element 24. The connection node between the photon detecting element 22 and the quench element 24 is the output node of the photoelectric conversion unit 20. The other terminal of the quench element 24 is connected to a node to which a voltage VH higher than the voltage VL is supplied. The voltages VL and VH are set so that a reverse bias voltage sufficient for the APD to perform avalanche multiplication operation is applied. For example, a negative high voltage is applied as the voltage VL, and a positive voltage approximately equal to the power supply voltage is applied as the voltage VH. For example, the voltage VL is −30 V, and the voltage VH is 1 V.

[0027] The photon detecting element 22 may be composed of an APD, as described above. When a reverse bias voltage sufficient for avalanche multiplication is applied to the APD, the charge generated by light incident on the APD undergoes avalanche multiplication, generating an avalanche current. When a reverse bias voltage is applied to the APD, the APD can operate in either Geiger mode or linear mode. In Geiger mode, a reverse bias voltage greater than the breakdown voltage of the APD is applied between the anode and cathode. In linear mode, a reverse bias voltage close to or less than the breakdown voltage of the APD is applied between the anode and cathode. An APD operating in Geiger mode is called a single photon avalanche diode (SPAD). The APD constituting the photon detecting element 22 may operate in either linear mode or Geiger mode. SPADs are particularly preferred because they have a larger potential difference and a more pronounced withstand voltage than linear mode APDs.

[0028] The quench element 24 has a function of converting a change in avalanche current generated in the photon detecting element 22 into a voltage signal. The quench element 24 also functions as a load circuit (quench circuit) during signal multiplication by avalanche multiplication, and has a function of reducing the voltage applied to the photon detecting element 22 to suppress avalanche multiplication. The operation of the quench element 24 to suppress avalanche multiplication is called a quench operation. The quench element 24 also has a function of returning the voltage supplied to the photon detecting element 22 to voltage VH by passing a current equivalent to the voltage drop caused by the quench operation. The operation of the quench element 24 to return the voltage supplied to the photon detecting element 22 to voltage VH is called a recharge operation. The quench element 24 can be configured using a resistor element, a MOS transistor, or the like.

[0029] The waveform shaping circuit 32 has an input node to which the output signal of the photoelectric conversion unit 20 is supplied, and an output node. The waveform shaping circuit 32 has a function of converting the analog signal supplied from the photoelectric conversion unit 20 into a pulse signal. The waveform shaping circuit 32 can be configured with logic circuits including a NOT circuit (inverter circuit), a NOR circuit, a NAND circuit, etc. The output node of the waveform shaping circuit 32 is connected to the processing circuit 34.

[0030] The processing circuit 34 may include an input node to which the output signal of the waveform shaping circuit 32 is supplied, an input node connected to the control line 14, and an output node. The processing circuit 34 is a functional block that performs predetermined processing on the pulse signal output from the waveform shaping circuit 32, and one example is a counter. If the processing circuit 34 is a counter, it may have the function of counting pulses superimposed on the signal output from the waveform shaping circuit 32 and retaining the count value resulting from the counting. Signals supplied to the processing circuit 34 from the vertical scanning circuit unit 40 via the control line 14 may include an enable signal for controlling the pulse count period (exposure period) and a reset signal for resetting the count value retained by the processing circuit 34. The output node of the processing circuit 34 is connected to the data line 16 via the pixel output circuit 36.

[0031] The pixel output circuit 36 ​​has a function of switching the electrical connection state (connected or disconnected) between the processing circuit 34 and the data line 16. The pixel output circuit 36 ​​switches the connection state between the processing circuit 34 and the data line 16 in response to a control signal supplied from the horizontal scanning circuit unit 60 via the control line 18 (in the configuration example of FIG. 2, a control signal supplied from the vertical scanning circuit unit 40 via the control line 14). The pixel output circuit 36 ​​may include a buffer circuit for outputting a signal.

[0032] The pixel 12 is typically a unit structure that outputs a pixel signal for forming an image. However, in cases where the purpose is distance measurement using a TOF (Time of Flight) method, the pixel 12 does not necessarily have to be a unit structure that outputs a pixel signal for forming an image. In other words, the pixel 12 can also be a unit structure that outputs a signal for measuring the time and amount of light arrival.

[0033] It is not necessary that one pixel signal processing unit 30 is provided for each pixel 12, but one pixel signal processing unit 30 may be provided for multiple pixels 12. In this case, the single pixel signal processing unit 30 can be used to sequentially perform signal processing for multiple pixels 12.

[0034] The photoelectric conversion device 100 according to this embodiment may be formed on a single substrate, or may be configured as a stacked photoelectric conversion device in which multiple substrates are stacked. In the latter case, for example, as shown in FIG. 4, a stacked photoelectric conversion device can be configured in which a sensor substrate 110 and a circuit substrate 180 are stacked and electrically connected. At least the photon detecting element 22, which is one of the components of the pixel 12, can be arranged on the sensor substrate 110. Furthermore, among the components of the pixel 12, the quenching element 24 and the pixel signal processing unit 30 can be arranged on the circuit substrate 180. The photon detecting element 22, the quenching element 24, and the pixel signal processing unit 30 are electrically connected via connection wiring provided for each pixel 12. Furthermore, the circuit substrate 180 can further include a vertical scanning circuit unit 40, a readout circuit unit 50, a horizontal scanning circuit unit 60, an output circuit unit 70, a control pulse generating unit 80, and the like.

[0035] The photon detecting element 22, quenching element 24, and pixel signal processing unit 30 of each pixel 12 are provided on the sensor substrate 110 and the circuit substrate 180 so as to overlap in a plan view. The vertical scanning circuit unit 40, readout circuit unit 50, horizontal scanning circuit unit 60, output circuit unit 70, and control pulse generating unit 80 can be arranged around the pixel unit 10 made up of a plurality of pixels 12. In this specification, "plan view" refers to a view from a direction perpendicular to the light incident surface of the sensor substrate 110.

[0036] Constructing a stacked photoelectric conversion device 100 makes it possible to increase the integration density of elements and achieve higher performance. In particular, by arranging the photon detecting elements 22, the quenching elements 24, and the pixel signal processing unit 30 on separate substrates, the photon detecting elements 22 can be arranged at high density without sacrificing the light receiving area of ​​the photon detecting elements 22, thereby improving photon detection efficiency.

[0037] The number of substrates constituting the photoelectric conversion device 100 is not limited to two, and the photoelectric conversion device 100 may be constituted by stacking three or more substrates.

[0038] 4, the sensor substrate 110 and the circuit substrate 180 are assumed to be diced chips, but the sensor substrate 110 and the circuit substrate 180 are not limited to chips. For example, the sensor substrate 110 and the circuit substrate 180 may each be a wafer. The sensor substrate 110 and the circuit substrate 180 may be stacked in the wafer state and then diced, or may be formed into chips and then stacked and bonded.

[0039] Next, the basic operation of the photoelectric conversion unit of the photoelectric conversion device according to this embodiment will be described with reference to Fig. 5. Fig. 5 is a diagram illustrating the basic operation of the photoelectric conversion unit of the photoelectric conversion device according to this embodiment. Fig. 5(a) is a circuit diagram of the photoelectric conversion unit 20 and the waveform shaping circuit 32, Fig. 5(b) shows the waveform of the signal at the input node (node ​​A) of the waveform shaping circuit 32, and Fig. 5(c) shows the waveform of the signal at the output node (node ​​B) of the waveform shaping circuit 32.

[0040] At time t0, a reverse bias voltage with a potential difference equivalent to (VH-VL) is applied to the photon detecting element 22. A reverse bias voltage sufficient to cause avalanche multiplication is applied between the anode and cathode of the APD that constitutes the photon detecting element 22, but there are no carriers to serve as seeds for avalanche multiplication when no photons are incident on the photon detecting element 22. Therefore, avalanche multiplication does not occur in the photon detecting element 22, and no current flows through the photon detecting element 22.

[0041] At subsequent time t1, a photon is incident on the photon detecting element 22. When a photon is incident on the photon detecting element 22, electron-hole pairs are generated by photoelectric conversion, and avalanche multiplication occurs using these carriers as seeds, causing an avalanche multiplication current to flow through the photon detecting element 22. This avalanche multiplication current flows through the quenching element 24, causing a voltage drop across the quenching element 24, and the voltage at node A begins to drop. The amount of voltage drop at node A increases, and when the avalanche multiplication stops at time t3, the voltage level at node A no longer drops.

[0042] When avalanche multiplication in the photon detecting element 22 stops, a current that compensates for the voltage drop flows from the node supplied with voltage VL to node A via the photon detecting element 22, and the voltage at node A gradually increases. After that, at time t5, node A settles to its original voltage level.

[0043] The waveform shaping circuit 32 binarizes the signal input from node A in accordance with a predetermined decision threshold and outputs the binarized signal from node B. Specifically, when the voltage level of node A exceeds the decision threshold, the waveform shaping circuit 32 outputs a low-level signal from node B, and when the voltage level of node A is equal to or lower than the decision threshold, the waveform shaping circuit 32 outputs a high-level signal from node B. For example, as shown in FIG. 5(b), assume that the voltage of node A is equal to or lower than the decision threshold during the period from time t2 to time t4. In this case, as shown in FIG. 5(c), the signal level at node B is low during the period from time t0 to time t2 and the period from time t4 to time t5, and is high during the period from time t2 to time t4.

[0044] In this way, the analog signal input from node A is waveform-shaped into a digital signal by the waveform shaping circuit 32. The pulse signal output from the waveform shaping circuit 32 in response to a photon incident on the photon detecting element 22 is a photon detection pulse signal.

[0045] When the processing circuit 34 constitutes a counter, the processing circuit 34 counts the photon detection pulse signals output from the waveform shaping circuit 32 in this manner and stores the count value as a digital signal. The pixel output circuit 36 ​​outputs the digital signal (pixel signal) stored in the processing circuit 34 to the data line 16 in response to a control signal supplied from the horizontal scanning circuit unit 60 via the control line 18.

[0046] Next, the structure of the photon detecting element 22 in the photoelectric conversion device according to this embodiment will be described with reference to Figs. 6 and 7. Fig. 6 is a cross-sectional view showing the structure of the photon detecting element in the photoelectric conversion device according to this embodiment. Fig. 7 is a plan view showing the structure of the photon detecting element in the photoelectric conversion device according to this embodiment. Fig. 6 is a cross-sectional view taken along line AA' in the plan view of Fig. 7.

[0047] The photoelectric conversion device according to this embodiment can be configured as a stacked photoelectric conversion device in which a sensor substrate 110 and a circuit substrate 180 are stacked, as shown in FIG.

[0048] The sensor substrate 110 includes a semiconductor layer 120 having a first surface 122 and a second surface 124 opposite to the first surface, and a wiring structure layer 140 provided on the first surface 122 side of the semiconductor layer 120. The second surface 124 side of the semiconductor layer 120 serves as a light receiving surface that receives light to be detected. In other words, the photoelectric conversion device of this embodiment is a so-called backside illuminated photoelectric conversion device. Note that an optical structure layer (not shown) including a color filter, a microlens, etc. may be provided on the second surface 124 side of the semiconductor layer 120.

[0049] The semiconductor layer 120 is a thinned single crystal silicon substrate and contains a predetermined concentration of N-type impurities or P-type impurities. As an example, the semiconductor layer 120 is assumed to be a thinned N-type silicon substrate.

[0050] The semiconductor layer 120 is provided with an N-type semiconductor region 126 and P-type semiconductor regions 128, 132, and 134. At least a portion of the N-type semiconductor region 126 reaches the first surface 122 of the semiconductor layer 120. The P-type semiconductor region 128 is disposed closer to the second surface 124 than the N-type semiconductor region 126, and forms a pn junction with the N-type semiconductor region 126. A depletion layer formed between the N-type semiconductor region 126 and the P-type semiconductor region 128 becomes the avalanche multiplication region 130.

[0051] The P-type semiconductor region 134 is provided on the second surface 124 side of the semiconductor layer 120. The P-type semiconductor region 132 is provided so as to surround the region in which the N-type semiconductor region 126 and the P-type semiconductor region 128 are provided in a plan view. The P-type semiconductor region 132 is provided from the first surface 122 of the semiconductor layer 120 to a depth where the P-type semiconductor region 134 is disposed. The region of the semiconductor layer 120 surrounded by the P-type semiconductor regions 132, 134 is a region (N-well 136) where one photon detecting element 22 is disposed. Adjacent photon detecting elements 22 are electrically isolated from each other by the P-type semiconductor regions 132, 134. The P-type semiconductor region 132 forms an isolation portion that electrically isolates the photon detecting elements 22 from each other.

[0052] The wiring structure layer 140 has an insulating layer 142, and wiring layers 146, 150, and 154 and contact electrodes 144, 148, and 152 arranged in the insulating layer 142. The wiring layer 146 is a wiring layer arranged at a distance from the first surface 122 of the semiconductor layer 120. The wiring layer 150 is a wiring layer arranged at a distance greater than the wiring layer 146 from the first surface 122 of the semiconductor layer 120. The wiring layer 154 is a wiring layer arranged at a distance greater than the wiring layer 150 from the first surface 122 of the semiconductor layer 120. The contact electrode 144 is a conductive member that electrically connects the N-type semiconductor region 126 and the P-type semiconductor region 132 to the wiring layer 146. The contact electrode 148 is a conductive member that electrically connects the wiring layer 146 to the wiring layer 150. The contact electrode 152 is a conductive member that electrically connects the wiring layer 150 to the wiring layer 154.

[0053] The wiring layer 146 has a wiring 156 electrically connected to the N-type semiconductor region 126 via the contact electrode 144, and a wiring 160 electrically connected to the P-type semiconductor region 132 via the contact electrode 144. The contact electrode 144 connecting the N-type semiconductor region 126 and the wiring 156 is connected to the N-type semiconductor region 126 in a portion where the N-type semiconductor region 126 reaches the first surface 122 of the semiconductor layer 120. The wiring layer 150 has a wiring 162 electrically connected to the wiring 156 via the contact electrode 148. The wiring layer 154 has a pad electrode 164 electrically connected to the wiring 162 via the contact electrode 152.

[0054] 6 illustrates the wiring structure layer 140 including three wiring layers 146, 150, and 154, but the number of wiring layers constituting the wiring structure layer 140 is not particularly limited. For example, one or more wiring layers may be further provided between the wiring layer 150 and the wiring layer 154. In this case, the wiring 162 and the pad electrode 164 are electrically connected via these wiring layers.

[0055] In the photoelectric conversion device of this embodiment, the insulating film constituting the insulating layer 142 includes, for example, a SiO2 film. Furthermore, as shown in FIG. 6, an insulating film 142a serving as an anti-reflection layer and an insulating film 142b having a lower refractive index than the insulating film 142a may be provided between the semiconductor layer 120 and the wiring layer 146 from the semiconductor layer 120 side. The insulating film 142a is not particularly limited, but may be, for example, a SiN film or a stack of a SiN film and a SiO2 film. By providing the insulating film 142a, light re-entering the first surface 122 from the wiring 156 is refracted at the interface between these insulating films and is incident more toward the photon detecting element 22. Therefore, in combination with the configurations of the wirings 156, 162, and the contact electrode 148 described in this embodiment, photons incident on the opening 158 can be reflected at an angle closer to the perpendicular direction and enter the photon detecting element 22. This further improves the photon detection efficiency of the photon detecting element 22.

[0056] The circuit board 180 is laminated on the wiring structure layer 140 side of the sensor substrate 110. A bonding surface 170 is the bonding portion between the sensor substrate 110 and the circuit board 180. The circuit board 180 has a semiconductor layer in which elements such as transistors are provided, and a wiring structure layer provided on the semiconductor layer. To simplify the drawing, FIG. 7 shows only a pad electrode 182 formed by the uppermost wiring layer of the semiconductor layers and wiring structure layers that make up the circuit board 180, a wiring 186 formed by the wiring layer below that, and a contact electrode 184 that connects these.

[0057] The pad electrode 164 of the sensor substrate 110 and the pad electrode 182 of the circuit substrate 180 are made of a metal material such as copper (Cu). As a result, the sensor substrate 110 and the circuit substrate 180 are electrically and mechanically coupled by intermetallic bonding between the metal material that makes up the pad electrode 164 and the metal material that makes up the pad electrode 182.

[0058] A negative voltage (voltage VL) is supplied to the N-type semiconductor region 126 from the circuit board 180 via the contact electrode 144, the wiring 156, the contact electrode 148, the wiring 162, the contact electrode 152, the pad electrodes 164 and 182, the contact electrode 184, the wiring 186, etc. Furthermore, a positive voltage (voltage VH) is supplied to the P-type semiconductor regions 132 and 134 from the circuit board 180 via the contact electrode 144, the wiring 160, etc. As a result, a reverse bias sufficient for avalanche multiplication is applied between the N-type semiconductor region 126 and the P-type semiconductor region 128, thereby forming the avalanche multiplication region 130. The high electric field formed in the avalanche multiplication region 130 multiplies electrons generated by photons incident on the photon detecting element 22.

[0059] The wiring 156, the contact electrode 148, and the wiring 162 form a wiring structure that serves as an electrical path for supplying a voltage VL to the N-type semiconductor region 126. This wiring structure also serves as a reflective member that reflects light that has passed through the semiconductor layer 120 and causes it to reenter the photon detecting element 22. For this purpose, the wiring 156 and the wiring 162 are arranged so that the entire avalanche multiplication region 130 overlaps with at least one of the wiring 156 and the wiring 162 in a planar view, as shown in FIG. 7 , for example. The avalanche multiplication region 130 is arranged inside the outer periphery of the wiring 156 in a planar view. An opening 158 is provided in the wiring 156 at a portion that overlaps with the avalanche multiplication region 130 in a planar view, and the wiring 162 is arranged so that the entire opening 158 overlaps with the opening 158 in a planar view. In other words, the wiring structure including the wiring 156 and the wiring 162 is arranged so that the entire avalanche multiplication region 130 overlaps with the opening 158 in a planar view. The contact electrode 148 is disposed around the opening 158 in a plan view.

[0060] Of the light incident from the second surface 124, light that passes through the photon detecting element 22 (semiconductor layer 120) is reflected by the surface of the wiring 156, or passes through the opening 158 and is reflected by the surface of the wiring 162 or the contact electrode 148, and then enters the photon detecting element 22 again. Therefore, by arranging the avalanche multiplication region 130 so that the entire region overlaps with at least one of the wiring 156 and the wiring 162 in a plan view, the photon detection efficiency of the photon detecting element 22 can be improved.

[0061] The opening 158 is provided in the wiring 156 in order to increase the efficiency with which reflected photons enter the photon detecting element 22. In other words, when reflecting light, compared to a structure in which only the wiring 156 has no opening, the presence of the opening 158, contact electrode 148, and wiring 162 is equivalent to a state in which a recess is formed on the surface of the wiring 156 facing the semiconductor layer 120. As a result, photons incident on the opening 158 are reflected at an angle closer to the parallel direction, and the optical path length in the photon detecting element 22 is lengthened, thereby increasing the proportion of photons that enter the photon detecting element 22.

[0062] Contact electrodes 148 electrically connecting wiring 156 and wiring 162 are arranged to surround opening 158 in plan view, as shown in FIG. 7, for example. In this case, it is desirable that the multiple contact electrodes 148 surrounding one opening 158 are arranged at intervals shorter than the length corresponding to the wavelength of light to which photon detecting element 22 is sensitive. This configuration makes it possible to prevent light incident on opening 158 from leaking out through gaps between contact electrodes 148. It is desirable that contact electrode 148 have a tapered shape in which the width in cross section is narrower on the wiring 156 side than on the wiring 162 side, as shown in FIG. 6, for example.

[0063] 7 illustrates an example of opening 158 having a rectangular shape in a plan view, the shape of opening 158 is not particularly limited, and may be, for example, a polygon other than a rectangle, a circle, an ellipse, etc. When opening 158 has a polygonal shape, it is desirable that at least one contact electrode 148 is disposed corresponding to each side of the polygonal shape.

[0064] When multiple openings 158 are provided in wiring 156, it is desirable to arrange these openings 158 at intervals of 1 μm or less. Furthermore, although an example in which openings 158 are arranged in a simple lattice pattern is shown in Fig. 7, the arrangement of openings 158 is not limited to this, and openings 158 may be arranged in a houndstooth pattern, for example.

[0065] The wiring 156, 162 and the contact electrode 148 are made of a material that has high reflectivity with respect to the light of the detection target. For example, the wiring 156, 162 and the contact electrode 148 can be made of a metal material such as copper (Cu), aluminum (Al), or tungsten (W), or an alloy material containing at least one of these metal materials.

[0066] As described above, according to this embodiment, the light-receiving sensitivity of the photoelectric conversion device can be effectively improved.

[0067] [Second embodiment] A photoelectric conversion device according to a second embodiment of the present invention will be described with reference to Fig. 8. Components similar to those in the photoelectric conversion device according to the first embodiment are given the same reference numerals, and descriptions thereof will be omitted or simplified. Fig. 8 is a cross-sectional view showing the structure of a photon detecting element in the photoelectric conversion device according to this embodiment.

[0068] In the photoelectric conversion device of this embodiment, of the insulating films constituting the insulating layer 142, the insulating film 166 provided between the wiring 156 and the wiring 162 has a higher refractive index than the insulating film provided between the semiconductor layer 120 and the insulating film 166. The insulating film 166 between the wiring 156 and the wiring 162 is not particularly limited, but may be, for example, a SiON film. Furthermore, the insulating film between the semiconductor layer 120 and the insulating film 166 is not particularly limited, but may be, for example, a SiO2 film. Other points are the same as those of the photoelectric conversion device according to the first embodiment.

[0069] By configuring the insulating film 166 provided between the wiring 156 and the wiring 162 from a material with a higher refractive index than the insulating film provided between the semiconductor layer 120 and the insulating film 166, light passing through the interface between these insulating films is refracted. Therefore, in combination with the configurations of the wirings 156, 162 and the contact electrode 148 described in the first embodiment, photons incident on the opening 158 are reflected at an angle closer to a parallel direction, and the optical path length in the photon detecting element 22 is lengthened. This further improves the photon detection efficiency of the photon detecting element 22.

[0070] As described above, according to this embodiment, the light-receiving sensitivity of the photoelectric conversion device can be effectively improved.

[0071] [Third embodiment] A photoelectric conversion device according to a third embodiment of the present invention will be described with reference to Fig. 9. Components similar to those of the photoelectric conversion devices according to the first and second embodiments are given the same reference numerals, and descriptions thereof will be omitted or simplified. Fig. 9 is a plan view showing the structure of a photon detecting element in the photoelectric conversion device according to this embodiment.

[0072] In the first embodiment, the planar pattern of the wiring 162 is designed so that the multiple openings 158 provided in the wiring 156 are covered by one continuous wiring 162, but the planar pattern of the wiring 162 is not limited to this.

[0073] 9, the plurality of openings 158 provided in the wiring 156 may be configured to be covered by a plurality of wirings 162 corresponding to the respective openings 158. Furthermore, a plurality of wirings 162 each covering a plurality of openings 158 may be provided for one wiring 156. The plurality of wirings 162 corresponding to one wiring 156 can be electrically connected to one another by wiring in an upper layer (for example, a pad electrode 164) or wiring in the circuit board 180.

[0074] The configuration of this embodiment can also achieve the same effects as the photoelectric conversion device of the first embodiment.

[0075] [Fourth embodiment] A photoelectric conversion device according to a fourth embodiment of the present invention will be described with reference to Figures 10 and 11. Components similar to those in the photoelectric conversion devices according to the first to third embodiments are given the same reference numerals, and descriptions thereof will be omitted or simplified. Figures 10 and 11 are plan views showing the structure of a photon detecting element in the photoelectric conversion device according to this embodiment.

[0076] In the first to third embodiments, a plurality of contact electrodes 148 are arranged to surround the opening 158, and the wiring 156 and the wiring 162 are electrically connected by these contact electrodes 148, but the shape and arrangement of the contact electrodes 148 are not limited to this.

[0077] For example, the contact electrode 148 may have a rectangular pattern along each side of the opening 158 in a plan view, as shown in Fig. 10. Alternatively, the contact electrode 148 may have a frame-like pattern surrounding the opening 158 in a plan view, as shown in Fig. 11.

[0078] The configuration of this embodiment can also achieve the same effects as the photoelectric conversion device of the first embodiment.

[0079] [Fifth embodiment] A light detection system according to a fifth embodiment of the present invention will be described with reference to Fig. 12. Fig. 12 is a block diagram showing a schematic configuration of the light detection system according to this embodiment. In this embodiment, a light detection sensor to which the photoelectric conversion device 100 according to the first to fourth embodiments is applied will be described.

[0080] The photoelectric conversion device 100 described in the first to fourth embodiments can be applied to various photodetection systems. Examples of applicable photodetection systems include imaging systems such as digital still cameras, digital camcorders, surveillance cameras, copiers, fax machines, mobile phones, vehicle-mounted cameras, and observation satellites. Camera modules equipped with an optical system such as a lens and an imaging device are also included in the photodetection system. Fig. 12 illustrates a block diagram of a digital still camera as an example of such systems.

[0081] 12 includes a photoelectric conversion device 201, a lens 202 that forms an optical image of a subject on the photoelectric conversion device 201, an aperture 204 that adjusts the amount of light passing through the lens 202, and a barrier 206 that protects the lens 202. The lens 202 and the aperture 204 form an optical system that focuses light on the photoelectric conversion device 201. The photoelectric conversion device 201 is the photoelectric conversion device 100 described in the first to fourth embodiments, and converts the optical image formed by the lens 202 into image data.

[0082] The photodetection system 200 also includes a signal processing unit 208 that processes an output signal output from the photoelectric conversion device 201. The signal processing unit 208 generates image data from the digital signal output by the photoelectric conversion device 201. The signal processing unit 208 also performs various corrections and compressions as necessary to output the image data. The photoelectric conversion device 201 may include an AD conversion unit that generates a digital signal to be processed by the signal processing unit 208. The AD conversion unit may be formed in a semiconductor layer (semiconductor substrate) on which the photon detection elements of the photoelectric conversion device 201 are formed, or may be formed on a semiconductor substrate separate from the semiconductor layer on which the photon detection elements of the photoelectric conversion device 201 are formed. The signal processing unit 208 may also be formed on the same semiconductor substrate as the photoelectric conversion device 201.

[0083] The light detection system 200 further includes a buffer memory unit 210 for temporarily storing image data, and an external interface unit (external I / F unit) 212 for communicating with an external computer or the like. The light detection system 200 also includes a recording medium 214 such as a semiconductor memory for recording or reading out imaging data, and a recording medium control interface unit (recording medium control I / F unit) 216 for recording or reading out imaging data from the recording medium 214. The recording medium 214 may be built into the light detection system 200 or may be removable. Communication between the recording medium control I / F unit 216 and the recording medium 214 and communication from the external I / F unit 212 may be performed wirelessly.

[0084] The photodetection system 200 further includes an overall control and calculation unit 218 that performs various calculations and controls the entire digital still camera, and a timing generation unit 220 that outputs various timing signals to the photoelectric conversion device 201 and the signal processing unit 208. Here, the timing signals and the like may be input from outside, and the photodetection system 200 only needs to include at least the photoelectric conversion device 201 and the signal processing unit 208 that processes the output signal output from the photoelectric conversion device 201. The timing generation unit 220 may be mounted on the photoelectric conversion device 201. The overall control and calculation unit 218 and the timing generation unit 220 may be configured to perform some or all of the control functions of the photoelectric conversion device 201.

[0085] The photoelectric conversion device 201 outputs an imaging signal to the signal processing unit 208. The signal processing unit 208 performs predetermined signal processing on the imaging signal output from the photoelectric conversion device 201 and outputs image data. The signal processing unit 208 generates an image using the imaging signal. The signal processing unit 208 may be configured to perform distance measurement calculations on the signal output from the photoelectric conversion device 201.

[0086] As described above, according to this embodiment, by configuring a light detection system using the photoelectric conversion devices of the first to fourth embodiments, it is possible to realize a light detection system capable of acquiring higher quality images.

[0087] [Sixth embodiment] A light detection system according to a sixth embodiment of the present invention will be described with reference to Fig. 13. Fig. 13 is a block diagram showing a schematic configuration of a range image sensor, which is an example of the light detection system according to this embodiment. In this embodiment, the range image sensor will be described as an example of a light detection system to which the photoelectric conversion device 100 of the first to fourth embodiments is applied.

[0088] 13, the range image sensor 300 according to this embodiment may include an optical system 302, a photoelectric conversion device 304, an image processing circuit 306, a monitor 308, and a memory 310. This range image sensor 300 receives light (modulated light or pulsed light) that is irradiated from a light source device 320 toward a subject 330 and reflected by the surface of the subject 330, and obtains a range image according to the distance to the subject 330.

[0089] The optical system 302 is composed of one or more lenses, and serves to focus image light (incident light) from the subject 330 onto the light receiving surface (sensor section) of the photoelectric conversion device 304.

[0090] The photoelectric conversion device 304 is the photoelectric conversion device 100 described in the first to fourth embodiments, and has the function of generating a distance signal indicating the distance to the subject 330 based on image light from the subject 330, and supplying the generated distance signal to the image processing circuit 306.

[0091] The image processing circuit 306 has a function of performing image processing to construct a distance image based on the distance signal supplied from the photoelectric conversion device 304 .

[0092] The monitor 308 has a function of displaying the distance image (image data) obtained by the image processing in the image processing circuit 306. The memory 310 has a function of storing (recording) the distance image (image data) obtained by the image processing in the image processing circuit 306.

[0093] Thus, according to this embodiment, by constructing a distance image sensor using the photoelectric conversion devices of the first to fourth embodiments, it is possible to realize a distance image sensor that can acquire distance images containing more accurate distance information, in combination with improved characteristics of pixel 12.

[0094] [Seventh embodiment] An optical detection system according to a seventh embodiment of the present invention will be described with reference to Fig. 14. Fig. 14 is a schematic diagram showing an example of the configuration of an endoscopic surgery system, which is an example of the optical detection system according to this embodiment. In this embodiment, the endoscopic surgery system will be described as an example of an optical detection system to which the photoelectric conversion device 100 according to the first to fourth embodiments is applied.

[0095] FIG. 14 shows a state in which an operator (doctor) 460 is performing surgery on a patient 472 on a patient bed 470 using an endoscopic surgery system 400.

[0096] 14, an endoscopic surgery system 400 of this embodiment may include an endoscope 410, a surgical tool 420, and a cart 430 on which various devices for endoscopic surgery are mounted. The cart 430 may be mounted with a CCU (camera control unit) 432, a light source device 434, an input device 436, a treatment tool control device 438, a display device 440, and the like.

[0097] The endoscope 410 includes a lens barrel 412, a region of which a predetermined length from the tip is inserted into a body cavity of a patient 472, and a camera head 414 connected to the base end of the lens barrel 412. Although Fig. 14 illustrates the endoscope 410 configured as a so-called rigid lens barrel having a rigid lens barrel 412, the endoscope 410 may also be configured as a so-called flexible lens barrel having a flexible lens barrel. The endoscope 410 is held in a movable state by an arm 416.

[0098] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 412. A light source device 434 is connected to the endoscope 410, and light generated by the light source device 434 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 412, and is irradiated via the objective lens towards an observation target inside the body cavity of the patient 472. The endoscope 410 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0099] An optical system and a photoelectric conversion device (not shown) are provided inside the camera head 414, and light reflected from the observation object (observation light) is collected by the optical system onto the photoelectric conversion device. The photoelectric conversion device photoelectrically converts the observation light and generates an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observation image. The photoelectric conversion device may be the photoelectric conversion device 100 described in the first to fourth embodiments. The image signal is transmitted to the CCU 432 as RAW data.

[0100] The CCU 432 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 410 and the display device 440. Furthermore, the CCU 432 receives an image signal from the camera head 414, and performs various image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0101] The display device 440 , under the control of the CCU 432 , displays an image based on the image signal that has been subjected to image processing by the CCU 432 .

[0102] The light source device 434 is configured from a light source such as an LED (Light Emitting Diode), and supplies the endoscope 410 with irradiation light when photographing an operation site or the like.

[0103] The input device 436 is an input interface for the endoscopic surgery system 400. A user can input various information and instructions to the endoscopic surgery system 400 via the input device 436.

[0104] The treatment tool control device 438 controls the driving of an energy treatment tool 450 for cauterizing tissue, incising, sealing blood vessels, or the like.

[0105] The light source device 434, which supplies illumination light to the endoscope 410 when photographing the surgical site, can be configured from a white light source configured from, for example, an LED, a laser light source, or a combination of these. When the white light source is configured from a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, making it possible to adjust the white balance of the captured image in the light source device 434. In this case, it is also possible to capture images corresponding to each RGB color in a time-division manner by irradiating the object of observation with laser light from each RGB laser light source in a time-division manner and controlling the drive of the image sensor of the camera head 414 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter to the image sensor.

[0106] Furthermore, the light source device 434 may be controlled to change the intensity of light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 414 in synchronization with the timing of the change in the light intensity to acquire images in a time-division manner and combining the images, it is possible to generate an image with a high dynamic range that is free of so-called blocked-up shadows and blown-out highlights.

[0107] The light source device 434 may also be configured to supply light in a predetermined wavelength band corresponding to special light observation. Special light observation utilizes, for example, the wavelength dependency of light absorption in body tissue. Specifically, by irradiating light with a narrower band than the light (i.e., white light) used in normal observation, a predetermined tissue, such as blood vessels on the surface of the mucosa, can be photographed with high contrast. Alternatively, special light observation may involve fluorescence observation, in which an image is obtained using fluorescence generated by irradiating excitation light. Fluorescence observation can involve irradiating excitation light onto a body tissue and observing the fluorescence from the body tissue, or locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the body tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 434 may be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0108] Thus, according to this embodiment, by configuring an endoscopic surgery system using the photoelectric conversion devices of the first to fourth embodiments, it is possible to realize an endoscopic surgery system that can acquire higher quality images.

[0109] [Eighth embodiment] An optical detection system and a moving body according to an eighth embodiment of the present invention will be described with reference to Figs. 15 to 17. Fig. 15 is a schematic diagram showing an example of the configuration of a moving body according to this embodiment. Fig. 16 is a block diagram showing a schematic configuration of an optical detection system according to this embodiment. Fig. 17 is a flow diagram showing the operation of the optical detection system according to this embodiment. In this embodiment, an example of application to an in-vehicle camera is shown as an optical detection system to which the photoelectric conversion device 100 according to the first to fourth embodiments is applied.

[0110] FIG. 15 is a schematic diagram showing an example of the configuration of a moving body (vehicle system) according to this embodiment. FIG. 15 shows the configuration of a vehicle 500 (automobile) as an example of a vehicle system incorporating a light detection system to which the photoelectric conversion device according to the first embodiment is applied. FIG. 15(a) is a schematic front view of the vehicle 500, FIG. 15(b) is a schematic plan view of the vehicle 500, and FIG. 15(c) is a schematic rear view of the vehicle 500. The vehicle 500 is provided with a pair of photoelectric conversion devices 502 on the front side. Here, the photoelectric conversion devices 502 are the photoelectric conversion devices 100 described in the first to fourth embodiments. The vehicle 500 also includes an integrated circuit 503, an alarm device 512, and a main control unit 513.

[0111] FIG. 16 is a block diagram showing an example configuration of a photodetection system 501 mounted on a vehicle 500. The photodetection system 501 includes a photoelectric conversion device 502, an image preprocessing unit 515, an integrated circuit 503, and an optical system 514. The photoelectric conversion device 502 is the photoelectric conversion device 100 described in the first embodiment. The optical system 514 forms an optical image of a subject on the photoelectric conversion device 502. The photoelectric conversion device 502 converts the optical image of the subject formed by the optical system 514 into an electrical signal. The image preprocessing unit 515 performs predetermined signal processing on the signal output from the photoelectric conversion device 502. The function of the image preprocessing unit 515 may be incorporated into the photoelectric conversion device 502. The photodetection system 501 includes at least two sets of the optical system 514, the photoelectric conversion device 502, and the image preprocessing unit 515, and the output from each set of the image preprocessing unit 515 is input to the integrated circuit 503.

[0112] The integrated circuit 503 is an integrated circuit for use in an imaging system, and includes an image processing unit 504, an optical distance measuring unit 506, a parallax calculation unit 507, an object recognition unit 508, and an abnormality detection unit 509. The image processing unit 504 processes an image signal output from an image pre-processing unit 515. For example, the image processing unit 504 performs image processing such as development processing and defect correction on the output signal of the image pre-processing unit 515. The image processing unit 504 includes a memory 505 that temporarily stores the image signal. For example, the positions of known defective pixels in the photoelectric conversion device 502 can be stored in the memory 505.

[0113] The optical distance measurement unit 506 performs focusing and distance measurement of the subject. The parallax calculation unit 507 calculates distance information (distance information) from multiple image data (parallax images) acquired by the multiple photoelectric conversion devices 502. Each of the photoelectric conversion devices 502 may be configured to be able to acquire various information such as distance information. The object recognition unit 508 recognizes subjects such as cars, roads, signs, and people. When the abnormality detection unit 509 detects an abnormality in the photoelectric conversion device 502, it notifies the main control unit 513 of the abnormality.

[0114] The integrated circuit 503 may be realized by dedicated hardware, a software module, or a combination thereof. It may also be realized by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like, or a combination thereof.

[0115] The main control unit 513 supervises and controls the operations of the light detection system 501, the vehicle sensor 510, the control unit 520, etc. Note that the vehicle 500 does not necessarily have to include the main control unit 513. In this case, the photoelectric conversion device 502, the vehicle sensor 510, and the control unit 520 transmit and receive control signals via a communication network. For example, the CAN standard may be applied to the transmission and reception of these control signals.

[0116] The integrated circuit 503 has a function of receiving a control signal from the main control unit 513 or transmitting a control signal or a set value to the photoelectric conversion device 502 by its own control unit.

[0117] The optical detection system 501 is connected to a vehicle sensor 510 and can detect the vehicle's driving conditions, such as vehicle speed, yaw rate, and steering angle, as well as the conditions of the environment outside the vehicle and other vehicles and obstacles. The vehicle sensor 510 also serves as a distance information acquisition means for acquiring distance information to an object. The optical detection system 501 is also connected to a driving assistance control unit 511 that performs various driving assistance functions, such as automatic steering, automatic cruising, and collision prevention functions. In particular, the collision determination function determines whether or not a collision with another vehicle or obstacle has occurred based on the detection results of the optical detection system 501 and the vehicle sensor 510. This allows for avoidance control when a collision is estimated, and activation of safety devices in the event of a collision.

[0118] The optical detection system 501 is also connected to an alarm device 512 that issues an alarm to the driver based on the determination result of the collision determination unit. For example, if the collision determination unit determines that there is a high possibility of a collision, the main control unit 513 performs vehicle control to avoid the collision and mitigate damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. The alarm device 512 warns the user by sounding an alarm or the like, displaying alarm information on a display screen of a car navigation system or meter panel, vibrating the seat belt or steering wheel, etc.

[0119] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are photographed by the light detection system 501. Fig. 15(b) shows an example of the arrangement of the light detection system 501 when the light detection system 501 photographs the area in front of the vehicle.

[0120] As described above, the photoelectric conversion device 502 is disposed in front of the vehicle 500. Specifically, if the center line of the vehicle 500's heading or outer shape (for example, vehicle width) is regarded as an axis of symmetry, and the two photoelectric conversion devices 502 are disposed symmetrically about the axis of symmetry, this is preferable for obtaining distance information between the vehicle 500 and an object to be photographed and determining the possibility of a collision. Furthermore, the photoelectric conversion device 502 is preferably disposed so as not to obstruct the driver's field of vision when the driver visually checks the situation outside the vehicle 500 from the driver's seat. The warning device 512 is preferably disposed so as to be easily within the driver's field of vision.

[0121] Next, a fault detection operation of the photoelectric conversion device 502 in the light detection system 501 will be described with reference to Fig. 16. The fault detection operation of the photoelectric conversion device 502 can be performed according to steps S110 to S180 shown in Fig. 16.

[0122] Step S110 is a step for performing startup settings for the photoelectric conversion device 502. That is, settings for the operation of the photoelectric conversion device 502 are transmitted from outside the photodetection system 501 (for example, from the main control unit 513) or from inside the photodetection system 501, and the image capturing operation and fault detection operation of the photoelectric conversion device 502 are started.

[0123] Next, in step S120, pixel signals are acquired from the effective pixels. Furthermore, in step S130, output values ​​are acquired from the failure detection pixels provided for failure detection. These failure detection pixels have photoelectric conversion elements, just like the effective pixels. A predetermined voltage is written to these photoelectric conversion elements. The failure detection pixels output signals corresponding to the voltage written to these photoelectric conversion elements. Note that steps S120 and S130 may be reversed.

[0124] Next, in step S140, a determination is made as to whether the expected output value of the fault detection pixel matches the actual output value from the fault detection pixel. If the result of the determination in step S140 indicates that the expected output value and the actual output value match, the process proceeds to step S150, where it is determined that the imaging operation is normal, and the process proceeds to step S160. In step S160, pixel signals of the scanning row are sent to the memory 505 and temporarily stored. Thereafter, the process returns to step S120, where the fault detection operation continues. On the other hand, if the result of the determination in step S140 indicates that the expected output value and the actual output value do not match, the process proceeds to step S170. In step S170, it is determined that an abnormality exists in the imaging operation, and an alarm is issued to the main control unit 513 or the alarm device 512. The alarm device 512 displays the detection of the abnormality on the display unit. Thereafter, in step S180, the photoelectric conversion device 502 is stopped, and the operation of the light detection system 501 is terminated.

[0125] In this embodiment, the flowchart is looped for each line, but the flowchart may be looped for each set of lines, or the fault detection operation may be performed for each frame. The issuance of the alarm in step S170 may be notified to the outside of the vehicle via a wireless network.

[0126] Furthermore, although the present embodiment has been described as a control for preventing collisions with other vehicles, the present invention is also applicable to control for automatic driving by following other vehicles, control for automatic driving so as not to deviate from a lane, and the like. Furthermore, the light detection system 501 is not limited to vehicles such as the subject vehicle, but can be applied to moving bodies (moving devices) such as ships, aircraft, and industrial robots. In addition, the present invention is not limited to moving bodies, but can be applied to a wide range of devices that use object recognition, such as intelligent transport systems (ITS).

[0127] [Ninth embodiment] A light detection system according to a ninth embodiment of the present invention will be described with reference to Fig. 18. Fig. 18 is a schematic diagram showing a configuration example of the light detection system according to this embodiment. In this embodiment, an example of application to eyeglasses (smart glasses) will be described as a light detection system to which the photoelectric conversion device 100 according to the first to fourth embodiments is applied.

[0128] 18(a) shows glasses 600 (smart glasses) according to one application example. The glasses 600 include lenses 601, a photoelectric conversion device 602, and a control device 603.

[0129] The photoelectric conversion device 602 is the photoelectric conversion device 100 described in the first embodiment, and is provided on the lens 601. There may be one or more photoelectric conversion devices 602. When multiple photoelectric conversion devices 602 are used, multiple types of photoelectric conversion devices 602 may be combined. The arrangement position of the photoelectric conversion devices 602 is not limited to that shown in FIG. 18(a). A display device (not shown) including a light-emitting device such as an OLED or LED may be provided on the back side of the lens 601.

[0130] The control device 603 functions as a power source that supplies power to the photoelectric conversion device 602 and the display device. The control device 603 also has a function of controlling the operations of the photoelectric conversion device 602 and the display device. The lens 601 is provided with an optical system for condensing light onto the photoelectric conversion device 602.

[0131] 18(b) shows glasses 610 (smart glasses) according to another application example. The glasses 610 include lenses 611 and a control device 612. The control device 612 may be equipped with a photoelectric conversion device (not shown) corresponding to the photoelectric conversion device 602 and a display device.

[0132] The lens 611 is provided with a photoelectric conversion device in the control device 612 and an optical system for projecting light from the display device, and an image is projected. The control device 612 functions as a power source that supplies power to the photoelectric conversion device and the display device, and also has a function of controlling the operations of the photoelectric conversion device and the display device.

[0133] The control device 612 may further include a gaze detection unit that detects the gaze of the wearer. In this case, an infrared light emitting unit may be provided in the control device 612, and the infrared light emitted from the infrared light emitting unit may be used to detect the gaze. Specifically, the infrared light emitting unit emits infrared light toward the eyeball of the user gazing at the displayed image. An imaging unit having a light receiving element detects the reflected light of the emitted infrared light from the eyeball, thereby obtaining an image of the eyeball. By providing a reduction unit that reduces the light from the infrared light emitting unit to the display unit in a planar view, it is possible to reduce degradation of image quality.

[0134] The user's line of sight with respect to the displayed image can be detected from an image of the eyeball obtained by capturing infrared light. Any known method can be applied to gaze detection using an image of the eyeball. As an example, a gaze detection method based on a Purkinje image formed by reflection of irradiated light on the cornea can be used. More specifically, a gaze detection process based on the pupil-corneal reflex method is performed. Using the pupil-corneal reflex method, a gaze vector representing the direction (rotation angle) of the eyeball is calculated based on the image of the pupil and the Purkinje image included in the image of the eyeball, thereby detecting the user's gaze.

[0135] The display device of this embodiment may include a photoelectric conversion device having a light receiving element, and may be configured to control a display image based on user line-of-sight information from the photoelectric conversion device. Specifically, the display device determines a first field of view area where the user gazes and a second field of view area other than the first field of view area based on the line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the display device or by an external control device. If determined by an external control device, they are communicated to the display device via communication. In the display area of ​​the display device, the display resolution of the first field of view area may be controlled to be higher than the display resolution of the second field of view area. In other words, the resolution of the second field of view area may be lower than the resolution of the first field of view area.

[0136] The display area may also be configured to have a first display area and a second display area different from the first display area, and to determine a high-priority area from the first display area and the second display area based on line-of-sight information. The first display area and the second display area may be determined by a control device of the display device or by an external control device. If determined by an external control device, the determination is communicated to the display device via communication. The resolution of the high-priority area may be controlled to be higher than the resolution of areas other than the high-priority area. In other words, the resolution of an area with a relatively low priority may be lowered.

[0137] Note that AI may be used to determine the first field of view area and areas with high priority. The AI ​​may be a model configured to estimate the angle of gaze and the distance to an object in the line of sight from an image of the eyeball, using as training data an image of the eyeball and the actual direction in which the eyeball in the image was looking. The AI ​​program may be included in the display device, the photoelectric conversion device, or an external device. If included in an external device, it is transmitted to the display device via communication.

[0138] When display control is performed based on visual recognition detection, the present invention is preferably applied to smart glasses that further include a photoelectric conversion device for capturing images of the outside world. The smart glasses can display captured external information in real time.

[0139] [Modified embodiment] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, an example in which part of the configuration of any one of the embodiments is added to another embodiment, or an example in which part of the configuration of another embodiment is substituted therefor, is also an embodiment of the present invention.

[0140] In addition, in the first embodiment, the opening 158 is provided inside the outer periphery of the wiring 156 in a plan view, but the opening 158 does not necessarily have to be located inside the outer periphery of the wiring 156. In other words, the opening 158 may form part of the outer periphery of the wiring 156. A part of the opening 158 does not have to overlap with the avalanche multiplication region 130 in a plan view.

[0141] Furthermore, the configuration of the pixel 12 shown in the first embodiment is an example, and the present invention is not limited to this.

[0142] For example, in the first embodiment, a signal is output from the connection node between the cathode of the photon detecting element 22 and the quenching element 24, but the configuration of the photoelectric conversion unit 20 is not limited to this. For example, the quenching element 24 may be connected to the anode side of the photon detecting element 22, and a signal may be output from the connection node between the anode of the photon detecting element 22 and the quenching element 24.

[0143] A switch such as a transistor may be provided between the photon detecting element 22 and the quenching element 24 or between the photoelectric conversion unit 20 and the pixel signal processing unit 30 to control the electrical connection state therebetween. A switch such as a transistor may be provided between the node to which the voltage VH is supplied and the quenching element 24 and / or between the node to which the voltage VL is supplied and the photon detecting element 22 to control the electrical connection state therebetween.

[0144] Furthermore, although a counter has been exemplified as the processing circuit 34 in the first embodiment, the processing circuit 34 may also be configured with a TDC (Time to Digital Converter) and a memory. In this case, the generation timing of the pulse signal output from the waveform shaping circuit 32 is converted into a digital signal by the TDC. When measuring the timing of the pulse signal, a control pulse pREF (reference signal) is supplied to the TDC from the vertical scanning circuit unit 40 via the control line 14. The TDC acquires, as a digital signal, a signal obtained when the input timing of the signal output from each pixel 12 is converted into a relative time based on the control pulse pREF.

[0145] Furthermore, in the above embodiment, adjacently arranged photon detecting elements 22 are electrically isolated from each other by the P-type semiconductor regions 132 and 134. However, an element isolation structure such as a DTI (Deep Trench Isolation) may be further provided inside the P-type semiconductor region 132. This element isolation structure may be provided so as to reach from the first surface 122 to the second surface 124 of the semiconductor layer 120, or may be provided in a portion of the depth direction between the first surface 122 and the second surface 124. Furthermore, the element isolation structure provided inside the P-type semiconductor region 132 may have a two-layer structure made of a reflective member that reflects light and an insulating member. Such a configuration enables further improvement in sensitivity.

[0146] It should be noted that the above-described embodiments are merely examples of specific embodiments for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited by these embodiments. In other words, the present invention can be carried out in various forms without departing from its technical concept or main features. [Explanation of symbols]

[0147] 12...pixels 20...Photoelectric conversion unit 22...Photon detection element 24...Quench element 30...Pixel signal processing unit 32...Waveform shaping circuit 34...Processing circuit 36...Pixel output circuit 100...Photoelectric conversion device 120...Semiconductor layer 130...Avalanche multiplication region 140...wiring structure layer 144, 148, 152, 184...Contact electrodes 146,150,154…wiring layer 156, 162, 186... Wiring 158...Opening 164, 182...Pad electrodes 166...insulating film

Claims

1. a semiconductor layer provided with an avalanche photodiode; a wiring structure layer provided on the first surface side of the semiconductor layer, the wiring structure layer is made of a metal material and has a wiring structure that overlaps an avalanche multiplication region of the avalanche photodiode in a plan view; the wiring structure includes a first wiring, a second wiring disposed farther from the first surface than the first wiring, and a plurality of contact electrodes electrically connecting the first wiring and the second wiring; the first wiring and the second wiring are included in adjacent wiring layers, and the plurality of contact electrodes are in contact with the first wiring and the second wiring; an opening is provided in a portion of the first wiring that overlaps with the avalanche multiplication region in a plan view; the second wiring is arranged to overlap the entire opening in a plan view, The plurality of contact electrodes are arranged to surround the opening in a plan view. A photoelectric conversion device characterized by:

2. The opening has a polygonal shape in a plan view, At least one of the plurality of contact electrodes is disposed corresponding to each side of the polygonal shape.

2. The photoelectric conversion device according to claim 1.

3. The plurality of contact electrodes are arranged at intervals shorter than a length corresponding to the wavelength of light to which the avalanche photodiode is sensitive.

3. The photoelectric conversion device according to claim 1 or 2.

4. A semiconductor layer provided with an avalanche photodiode; a wiring structure layer provided on the first surface side of the semiconductor layer, the wiring structure layer is made of a metal material and has a wiring structure that overlaps an avalanche multiplication region of the avalanche photodiode in a plan view; the wiring structure includes a first wiring, a second wiring disposed farther from the first surface than the first wiring, and a contact electrode electrically connecting the first wiring and the second wiring; the first wiring and the second wiring are included in adjacent wiring layers, and the contact electrode is in contact with the first wiring and the second wiring; an opening is provided in a portion of the first wiring that overlaps with the avalanche multiplication region in a plan view; the second wiring is arranged to overlap the entire opening in a plan view, The contact electrode is a frame-shaped structure that surrounds the opening. A photoelectric conversion device characterized by:

5. the wiring structure layer further includes a first insulating film disposed between the first wiring and the second wiring, and a second insulating film disposed between the first insulating film and the semiconductor layer; The refractive index of the first insulating film is higher than the refractive index of the second insulating film.

5. The photoelectric conversion device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

6. The avalanche multiplication region is disposed inside the outer periphery of the first wiring in a plan view.

6. The photoelectric conversion device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

7. The wiring structure is electrically connected to the avalanche photodiode.

7. The photoelectric conversion device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

8. At least one of the first wiring, the second wiring, and the contact electrode contains copper.

8. The photoelectric conversion device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

9. The wiring structure layer has an anti-reflection layer on the first surface of the semiconductor layer.

8. The photoelectric conversion device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

10. The first wiring has a plurality of openings.

10. The photoelectric conversion device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

11. The second wiring is disposed so as to overlap with the plurality of openings.

11. The photoelectric conversion device according to claim 10.

12. a plurality of second wirings corresponding to the plurality of openings; 11. The photoelectric conversion device according to claim 10.

13. The contact electrode has a tapered shape in which the width on the side of the first wiring is narrower than the width on the side of the second wiring.

13. The photoelectric conversion device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

14. a plurality of avalanche photodiodes and an isolation portion is provided in the semiconductor layer to isolate the plurality of avalanche photodiodes; The separating portion includes a reflecting member that reflects light.

14. The photoelectric conversion device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

15. The semiconductor layer further includes an optical structure layer provided on a second surface side opposite to the first surface.

15. The photoelectric conversion device according to claim 1.

16. The image sensor includes a plurality of pixels, each of which includes a photoelectric conversion unit that has the avalanche photodiode and outputs a signal in response to the incidence of a photon, a processing circuit that processes the signal output from the photoelectric conversion unit, and a pixel output circuit that controls the output of the signal processed by the processing circuit.

16. The photoelectric conversion device according to claim 1,

17. a first substrate on which at least the avalanche photodiode of the photoelectric conversion unit is provided, and a second substrate on which the processing circuit and the pixel output circuit are provided, stacked together; 17. The photoelectric conversion device according to claim 16.

18. The wiring structure overlaps the entire avalanche multiplication region of the avalanche photodiode in a plan view.

18. The photoelectric conversion device according to claim 1.

19. The photoelectric conversion device according to any one of claims 1 to 18, a signal processing device that processes a signal output from the photoelectric conversion device; An optical detection system comprising:

20. The signal processing device generates a distance image representing distance information to an object based on the signal.

20. The optical detection system of claim 19.

21. A mobile object, The photoelectric conversion device according to any one of claims 1 to 18, a distance information acquisition means for acquiring distance information to an object from a parallax image based on a signal output from the photoelectric conversion device; a control means for controlling the moving object based on the distance information; A moving object characterized by having:

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