Photoelectric converter, imaging system, and mobile unit

Abstract

To provide a photoelectric conversion device having more improved sensitivity.SOLUTION: A photoelectric conversion device comprising a plurality of pixels formed on a substrate is provided, comprising: a plurality of pixel separation portion provided between a plurality of adjacent pixels; and recessed and projected structure formed on a light-receiving surface of the substrate, wherein the recessed and projected structure includes a trench extending diagonally from the light-receiving surface into the inside of the substrate, and inside the trench, substance is included which is different in material from the substrate surrounding the trench or has a refractive index different from that of the substrate.SELECTED DRAWING: Figure 6

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a photoelectric conversion device in which a concavo-convex structure is provided on the light-receiving surface of a photoelectric conversion element to improve the quantum efficiency.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the concavo-convex structure disclosed in Patent Document 1 may not always be sufficient from the viewpoint of sensitivity to incident light.

[0005] An object of the present invention is to provide a photoelectric conversion device, an imaging system, and a moving body that can further improve sensitivity.

Means for Solving the Problems

[0006] According to one aspect of the present invention, there is provided a photoelectric conversion device including a plurality of pixels formed on a substrate, the photoelectric conversion device including a pixel separation portion provided between adjacent pixels and a concavo-convex structure formed on a light-receiving surface of the substrate, the concavo-convex structure including a trench obliquely extending from the light-receiving surface into the substrate, and the trench containing a material different from the substrate or a substance having a refractive index different from that of the substrate and located around the trench.

Effects of the Invention

[0007] According to the present invention, a photoelectric conversion device, an imaging system, and a mobile body are provided that can further improve sensitivity. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of the photoelectric conversion device in the first embodiment. [Figure 2] This figure shows an example of the arrangement of the sensor substrate in the first embodiment. [Figure 3] This figure shows an example of the circuit board arrangement in the first embodiment. [Figure 4] This is a circuit diagram of the APD and pulse generation unit in the first embodiment. [Figure 5] This figure shows the relationship between the operation of the APD and the output signal in the first embodiment. [Figure 6] This is a cross-sectional view of multiple adjacent pixels in the first embodiment. [Figure 7] This is a cross-sectional view of the uneven structure in the first embodiment. [Figure 8A] This is a plan view of the uneven structure in the first embodiment along the line A-A'. [Figure 8B] This is a plan view of the uneven structure in the first embodiment along the line B-B'. [Figure 8C] This is a plan view of the uneven structure in the first embodiment along the C-C' line. [Figure 9A] This is a cross-sectional view of the uneven structure in the first embodiment. [Figure 9B] This is a cross-sectional view of the uneven structure in the first embodiment. [Figure 10] This is a cross-sectional view of the uneven structure in the second embodiment. [Figure 11] This is a cross-sectional view of the uneven structure in the third embodiment. [Figure 12A] This is a plan view of the uneven structure in the third embodiment along the line A-A'. [Figure 12B] This is a plan view of the uneven structure along the line B-B' in the third embodiment. [Figure 12C]It is a plan view of the concavo-convex structure in the C-C' line in the third embodiment. [Figure 13] It is a cross-sectional view of the concavo-convex structure in the fourth embodiment. [Figure 14A] It is a plan view of the concavo-convex structure in the A-A' line in the fourth embodiment. [Figure 14B] It is a plan view of the concavo-convex structure in the B-B' line in the fourth embodiment. [Figure 14C] It is a plan view of the concavo-convex structure in the C-C' line in the fourth embodiment. [Figure 15] It is a cross-sectional view of the concavo-convex structure in the fifth embodiment. [Figure 16A] It is a plan view of the concavo-convex structure in the A-A' line in the fifth embodiment. [Figure 16B] It is a plan view of the concavo-convex structure in the B-B' line in the fifth embodiment. [Figure 16C] It is a plan view of the concavo-convex structure in the C-C' line in the fifth embodiment. [Figure 17] It is a cross-sectional view of the concavo-convex structure in the sixth embodiment. [Figure 18A] It is a plan view of the concavo-convex structure in the A-A' line in the sixth embodiment. [Figure 18B] It is a plan view of the concavo-convex structure in the B-B' line in the sixth embodiment. [Figure 18C] It is a plan view of the concavo-convex structure in the C-C' line in the sixth embodiment. [Figure 19A] It is a plan view of the concavo-convex structure in the seventh embodiment. [Figure 19B] It is a plan view of the concavo-convex structure in the seventh embodiment. [Figure 19C] It is a plan view of the concavo-convex structure in the seventh embodiment. [Figure 20] It is a cross-sectional view of the concavo-convex structure in the eighth embodiment. [Figure 21A] It is a plan view of the concavo-convex structure in the A-A' line in the eighth embodiment. [Figure 21B] It is a plan view of the concavo-convex structure in the B-B' line in the eighth embodiment. [Figure 21C] This is a plan view of the uneven structure along the C-C' line in the eighth embodiment. [Figure 22A] This is a plan view of the uneven structure in the eighth embodiment. [Figure 22B] This is a plan view of the uneven structure in the eighth embodiment. [Figure 23] This is a cross-sectional view of the photoelectric converter in the ninth embodiment. [Figure 24] This is a cross-sectional view of the uneven structure in the tenth embodiment. [Figure 25] This is a cross-sectional view of the uneven structure in the 11th embodiment. [Figure 26] This is a cross-sectional view of the uneven structure in the 11th embodiment. [Figure 27] This is a cross-sectional view of multiple adjacent pixels in the 12th embodiment. [Figure 28] This is a block diagram of the imaging system in the 13th embodiment. [Figure 29] This is a block diagram of the photodetection system in the 14th embodiment. [Figure 30] This is a schematic diagram of the endoscopic surgical system in the 15th embodiment. [Figure 31A] This is a schematic diagram of the photodetection system in the 16th embodiment. [Figure 31B] This is a schematic diagram of the moving body in the 16th embodiment. [Figure 32] This is a flowchart illustrating the operation of the photodetection system in the 16th embodiment. [Figure 33] This figure shows a specific example of an electronic device in the 17th embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. The embodiments shown below are intended to embody the technical concept of the present invention and do not limit the present invention. The size and positional relationships of the components shown in each drawing may be exaggerated for clarity of explanation. In the following description, identical components may be given the same number and their explanation may be omitted.

[0010] In the following description, terms indicating specific directions or positions (e.g., "up," "down," "right," "left," and other terms including these) will be used as needed. The use of these terms is for the purpose of facilitating the understanding of embodiments with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention.

[0011] [First Embodiment] The configuration of the photoelectric converter in this embodiment will be explained using Figures 1 to 4. The photoelectric converter has SPAD pixels including an avalanche photodiode (hereinafter referred to as "APD"). The conductivity type of the charge used as the signal charge among the charge pairs generated in the APD is called the first conductivity type. The first conductivity type refers to a conductivity type in which the majority carriers are charges of the same polarity as the signal charge. The conductivity type opposite to the first conductivity type is called the second conductivity type. Below, an example is described in which the signal charge is an electron, the first conductivity type is N-type, and the second conductivity type is P-type, but the signal charge may be a hole, the first conductivity type may be P-type, and the second conductivity type may be N-type.

[0012] Figure 1 is a schematic diagram of the photoelectric converter in this embodiment, showing the configuration of a stacked type photoelectric converter 100. The photoelectric converter 100 includes a sensor substrate (first substrate) 1 and a circuit board (second substrate) 2 stacked on top of each other, and the sensor substrate 1 and the circuit board 2 are electrically connected to each other. The photoelectric converter in this embodiment is a back-illuminated type photoelectric converter in which light is incident from the first surface of the sensor substrate 1 and the circuit board 2 is arranged on the second surface of the sensor substrate 1. The sensor substrate 1 has a first semiconductor layer having a photoelectric conversion element described later and a first wiring structure. The circuit board 2 has a second semiconductor layer having a circuit such as a signal processing unit described later and a second wiring structure. The second semiconductor layer, the second wiring structure, the first wiring structure, and the first semiconductor layer are stacked in that order to constitute the photoelectric converter 100.

[0013] In the following description, the sensor substrate 1 and the circuit board 2 may be, but are not limited to, diced chips. For example, each substrate may be a wafer. Furthermore, each substrate may be stacked in a wafer state and then diced, or it may be made into chips and then stacked and bonded together. The sensor substrate 1 has a pixel region 1a, and the circuit board 2 has a circuit region 2a that processes the signals detected by the pixel region 1a.

[0014] Figure 2 shows an example of the arrangement of the sensor substrate 1. Multiple pixels 10 each contain an APD 11 and are arranged in a two-dimensional array in a planar view, forming a pixel region 1a.

[0015] Pixel 10 is typically a pixel used to form an image, but when used in TOF (Time of Flight), it is not necessarily required to form an image. In other words, pixel 10 may be a pixel used to measure the time and amount of light that arrives.

[0016] Figure 3 shows an example of the arrangement of the circuit board 2. The circuit board 2 has a signal processing unit 20, a vertical scanning circuit 21, a readout circuit 23, a horizontal scanning circuit 27, an output calculation unit 24, a control pulse generation circuit 25, scan lines 26, and signal lines 29. In a plan view, the circuit area 2a is arranged in the area that overlaps with the pixel area 1a in Figure 2. Furthermore, in a plan view, the vertical scanning circuit 21, readout circuit 23, horizontal scanning circuit 27, output calculation unit 24, and control pulse generation circuit 25 are arranged so as to overlap with the area between the edge of the sensor board 1 in Figure 2 and the edge of the pixel area 1a. In other words, the sensor board 1 has a pixel area 1a and a non-pixel area arranged around the pixel area 1a, and the vertical scanning circuit 21, readout circuit 23, horizontal scanning circuit 27, output calculation unit 24, and control pulse generation circuit 25 are arranged in the area that overlaps with the non-pixel area in a plan view.

[0017] The signal processing unit 20 is electrically connected to the pixels 10 via connecting wiring provided for each pixel 10, and is arranged in a two-dimensional array in a planar view, similar to the pixels 10. The signal processing unit 20 includes a binary counter that counts the photons incident on the pixels 10.

[0018] The vertical scanning circuit 21 receives control pulses supplied from the control pulse generation circuit 25 and supplies control pulses to the signal processing unit 20 corresponding to the pixels 10 of each row via the scan line 26. The vertical scanning circuit 21 may be composed of logic circuits such as a shift register and an address decoder.

[0019] The readout circuit 23 acquires the pulse count value of the digital signal from the signal processing unit 20 of each row via the signal line 29. Then, it outputs the output signal to an external signal processing circuit (signal processing device) of the photoelectric converter 100 via the output calculation unit 24. The readout circuit 23 may also have the function of a signal processing circuit that performs correction of the count value. The horizontal scanning circuit 27 receives control pulses from the control pulse generation circuit 25 and sequentially outputs the count value of each column in the readout circuit 23 to the output calculation unit 24. As will be described later, if the pulse count value exceeds the threshold, the output calculation unit 24 estimates the actual image signal (pulse count value) based on the time count value and threshold included in the additional information and replaces the pulse count value with the estimated pulse count value (extrapolation). On the other hand, if the pulse count value is below the threshold, the pulse count value is output as is as the image signal.

[0020] The output calculation unit 24 performs predetermined processing on the pulse count value read by the readout circuit 23 and outputs the image signal to the outside. Furthermore, as will be described later, the output calculation unit 24 can perform processing such as calculation of the pulse count value when the pulse count value exceeds a threshold.

[0021] In Figure 2, the arrangement of photoelectric conversion elements in the pixel region 1a may be arranged in a one-dimensional manner. Furthermore, the effects of the present invention can be achieved even in a configuration with only one pixel 10, and a configuration with one pixel 10 can also be included in the present invention. In a photoelectric conversion device having multiple pixels 10, the effect of suppressing the circuit size according to this embodiment becomes even more pronounced. The signal processing unit 20 does not necessarily need to be provided for each pixel 10; for example, one signal processing unit 20 may be shared by multiple pixels 10, and signal processing may be performed sequentially.

[0022] Figure 4 is a block diagram of the APD and pulse generation unit in this embodiment. Figure 4 shows the pixel 10 of the sensor substrate 1 and the pulse generation unit 22 in the signal processing unit 20 of the circuit board 2. An APD 11 is placed in the pixel 10. The pulse generation unit 22 includes a quench element 221, a waveform shaping unit 222, a counter circuit 223, and a selection circuit 224.

[0023] The APD11 generates charge pairs corresponding to incident light through photoelectric conversion. A voltage VL (first voltage) is supplied to the anode of the APD11. In addition, a voltage VH (second voltage), which is higher than the voltage VL supplied to the anode, is supplied to the cathode of the APD11. A reverse bias voltage is applied to the anode and cathode, making the APD11 capable of avalanche multiplication. When a photon is incident on the APD11 under the reverse bias voltage, the charge generated by the photon undergoes avalanche multiplication, and an avalanche current is generated.

[0024] Depending on the reverse bias voltage, the APD11 can operate in Geiger mode or linear mode. Geiger mode is operation when the potential difference between the anode and cathode is greater than the breakdown voltage, while linear mode is operation when the potential difference between the anode and cathode is near or below the breakdown voltage. An APD operating in Geiger mode is specifically called a SPAD or SPAD type. For example, the voltage VL (first voltage) may be -30V and the voltage VH (second voltage) may be 1V. The APD11 may operate in linear mode or in Geiger mode. When the APD11 operates as a SPAD, the potential difference becomes larger compared to the linear mode APD11, and the voltage withstand effect becomes more pronounced, so it is preferable for the APD11 to operate as a SPAD.

[0025] The quench element 221 is placed between the power line supplying voltage VH and the cathode of the APD11. The quench element 221 functions as a load circuit (quench circuit) during signal multiplication by avalanche multiplication, suppressing the voltage supplied to the APD11 and thereby suppressing avalanche multiplication (quench operation). In addition, the quench element 221 also works to restore the voltage supplied to the APD11 to voltage VH by flowing current to compensate for the voltage drop caused by the quench operation (recharge operation).

[0026] The waveform shaping unit 222 functions as a signal generation unit that generates a detection pulse based on the output generated by the incidence of photons. That is, the waveform shaping unit 222 shapes the potential change of the cathode of the APD 11 obtained when a photon is detected and outputs a rectangular wave pulse signal (detection pulse). For example, an inverter circuit can be used as the waveform shaping unit 222. Figure 4 shows an example in which one inverter is used as the waveform shaping unit 222, but a circuit in which multiple inverters are connected in series may be used. In addition, other circuits that have a waveform shaping effect may be used.

[0027] The counter circuit 223 counts the pulse signals output from the waveform shaping unit 222 and holds the count value. The counter circuit 223 is also supplied with control pulses from the vertical scanning circuit 21 in Figure 3 via the drive line 226 of the scan line 26. When the control pulse becomes active, the signal held by the counter circuit 223 is reset.

[0028] The selection circuit 224 includes a switch circuit, a buffer circuit for outputting signals, and the like. The selection circuit 224 is supplied with control pulses from the vertical scanning circuit 21 in Figure 3 via the drive line 227. In response to the control pulses, the selection circuit 224 switches the electrical connection between the counter circuit 223 and the signal line 219.

[0029] Furthermore, switches such as transistors may be provided between the quench element 221 and the APD11, and between the APD11 and the signal processing unit 20. In addition, the supply of voltage VH or voltage VL may be electrically switched by switches such as transistors.

[0030] Figure 5 shows the relationship between the operation of the APD and the output signal in this embodiment. Figure 5(a) is an excerpt of the APD11, quench element 221, and waveform shaping unit 222 from Figure 4. When the input side of the waveform shaping unit 222 is nodeA and the output side is nodeB, Figure 5(b) shows the waveform change of nodeA, and Figure 5(c) shows the waveform change of nodeB.

[0031] Between time t0 and time t1, a reverse bias voltage of VH-VL is applied to APD11. When a photon is incident on APD11 at time t1, avalanche multiplication occurs in APD11, an avalanche multiplication current flows through the quench element 221, and the voltage at nodeA drops. As the voltage drop increases further and the potential difference applied to APD11 decreases, the avalanche multiplication of APD11 stops at time t3, and the voltage level at nodeA stops dropping below a certain value. Subsequently, between time t3 and time t5, a current flows from voltage VL to nodeA to compensate for the voltage drop, and at time t5, nodeA settles to its original voltage level. At this time, between time t2 and time t4, when the voltage level at nodeA falls below the threshold of the waveform shaping unit 222, nodeB becomes high level. In other words, the voltage waveform of nodeA is shaped by the waveform shaping unit 222, and a square wave pulse signal is output from nodeB.

[0032] The structure of the pixel 10 according to this embodiment will be explained using Figures 6 to 8C. Figure 6 is a cross-sectional view of a plurality of adjacent pixels. As shown in Figure 6, the pixel 10 includes a semiconductor layer 110 and an insulating layer 140.

[0033] The semiconductor layer 110 includes a plurality of semiconductor regions that constitute the APD 11. The semiconductor layer 110 has a first surface to which light is incident and a second surface which is the surface opposite to the first surface. In this specification, the depth direction is the direction from the first surface to the second surface of the semiconductor layer 110 in which the APD 11 is arranged. Hereinafter, the "first surface" may be referred to as the "back surface" or "light-receiving surface," and the "second surface" may be referred to as the "front surface." The direction from a predetermined position on the semiconductor layer 110 toward the surface of the semiconductor layer 110 may be expressed as "deep." Also, the direction from a predetermined position on the semiconductor layer 110 toward the back surface of the semiconductor layer 110 may be expressed as "shallow."

[0034] The semiconductor layer 110 is formed from silicon (Si), indium gallium arsenide (InGaAs), etc. The semiconductor layer 110 has a first semiconductor region 111, a second semiconductor region 112, a third semiconductor region 113, and a fourth semiconductor region 114. The first semiconductor region 111, which is of the first conductivity type, and the second semiconductor region 112, which is of the second conductivity type, form a PN junction. The impurity concentration in the first semiconductor region 111 is higher than that in the second semiconductor region 112. In addition, a predetermined reverse bias voltage is applied to the first semiconductor region 111 and the second semiconductor region 112, thereby forming an avalanche multiplication region of the APD 11.

[0035] As shown in Figure 6, a third semiconductor region 113 of the second conductivity type is located in the same layer as the first semiconductor region 111. The third semiconductor region 113 is also located at a shallower position than the second semiconductor region 112. Furthermore, the impurity concentration of the third semiconductor region 113 is lower than that of the second semiconductor region 112. The third semiconductor region 113 is a region that absorbs light incident from the light-receiving surface. A fourth semiconductor region 114 of the second conductivity type is located at a shallower position than the third semiconductor region 113. The impurity concentration of the fourth semiconductor region 114 is higher than that of the third semiconductor region 113. On the light-receiving surface side of the fourth semiconductor region 114, an uneven structure 170 including a plurality of trenches 171, which will be described later, is formed.

[0036] Between multiple adjacent pixels 10, a pixel isolation section 120 is provided, having a structure in which an insulator (dielectric) is embedded in the semiconductor layer 110. The pixel isolation section 120 has a deep trench isolation (DTI) structure. The pixel isolation section 120 is formed by etching or the like. The pixel isolation section 120 is formed shallower than the thickness of the semiconductor layer 110 from the light-receiving surface side. In this embodiment, the pixel isolation section 120 is formed so that its width gradually decreases from the light-receiving surface side toward the surface side. That is, the pixel isolation section 120 has a wedge shape. The pixel isolation section 120 repeatedly reflects incident light inside the semiconductor layer 110, thereby improving the efficiency of photoelectric conversion in the semiconductor layer 110 and the sensitivity of the pixels. By forming the pixel isolation section 120 in a wedge shape, the lateral reflection efficiency in the semiconductor layer 110 can be increased.

[0037] The pixel separation portion 120 may be formed in a cylindrical shape or a prismatic shape. Furthermore, the pixel separation portion 120 may be formed from the second surface side, which is the surface facing the light-receiving surface, or it may be formed to penetrate the semiconductor layer 110. In a plan view, the pixel separation portion 120 may be formed to surround the entire pixel 10, or to partially surround it. As the insulator used for the pixel separation portion 120, a dielectric material having a lower refractive index than the semiconductor element, such as silicon oxide, may be used. In addition to an insulator, a metal may be used for the pixel separation portion 120 to enhance light shielding, and voids may be included. For example, a thin insulating layer may be formed on the sidewall portion of the DTI structure, and metal may be filled into this insulating layer. The pixel separation portion 120 can suppress the transmission of incident light to adjacent pixels. That is, by separating one pixel from other pixels using the pixel separation portion 120, crosstalk with adjacent pixels can be reduced.

[0038] An insulating layer 140 is provided on the light-receiving surface side of the semiconductor layer 110 to flatten the surface into which light is incident. The insulating layer 140 is formed using a dielectric material such as silicon oxide (SiO2) or silicon nitride (Si3N4). A microlens 160 is formed on the surface of the insulating layer 140 on the side into which light is incident, to focus the incident light onto the pixel 10.

[0039] A wiring layer 190, included in the first wiring structure shown in Figure 1, is formed on the second surface side of the first semiconductor region 111. The wiring layer 190 is made of a conductive material that has the property of reflecting incident light that has passed through the light-receiving surface. The wiring layer 190 can function as a reflective layer that reflects light incident from the light-receiving surface and emitted to the surface back towards the semiconductor layer 110. By providing the wiring layer 190, the reflection of incident light within the semiconductor layer 110 can be promoted, improving the efficiency of photoelectric conversion.

[0040] A pinning layer may be further provided between the light-receiving surface side of the semiconductor layer 110 on which the uneven structure 170 is formed and the insulating layer 140. The pinning layer can be formed by chemical vapor deposition or the like using a high dielectric material such as hafnium oxide (HfO2), aluminum oxide (Al2O3), or silicon nitride (Si3N4). The pinning layer has a shape corresponding to the shape of the uneven structure 170, and it is desirable that it be formed to be sufficiently thin relative to the depth of the recesses of the uneven structure 170. By forming a pinning layer, dark current mediated by defects present on the light-receiving surface side of the semiconductor layer 110 can be suppressed. Here, a defect is, for example, an interface defect between the semiconductor layer 110 and the insulating layer 140 provided thereon.

[0041] A light-shielding portion 150 is provided between the pixel separation portion 120 and the insulating layer 140, as shown in Figure 6. A material with known light-shielding properties can be used for the light-shielding portion 150. By forming the light-shielding portion 150, crosstalk with adjacent pixels can be further reduced.

[0042] Furthermore, a filter layer may be provided between the microlens 160 and the semiconductor layer 110. Various optical filters such as color filters, infrared light cut filters, and monochrome filters can be used as the filter layer. In addition, RGB color filters, RGBW color filters, etc., can be used as the color filter.

[0043] Figure 7 is a cross-sectional view of the uneven structure in this embodiment. Figures 8A to 8C are plan views parallel to the light-receiving surface along lines A-A', B-B', and C-C' of the uneven structure in Figure 7.

[0044] The uneven structure 170 includes a trench 171 that extends diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110, and the trench 171 includes an opening 171a, a bottom 171b, and an intermediate portion 171c. In the plan view of Figure 8A, the opening 171a is circular, and the diameter d1 of the opening 171a is, for example, 0.2 μm or less, preferably 0.1 μm or less. In order to increase the diffraction of incident light within the semiconductor layer 110, it is desirable that the diameter d1 of the opening 171a be smaller than the depth of the trench 171. In the plan views of Figures 8B and 8C, the intermediate portion 171c of the trench 171 is annular and constitutes a ring portion with a width w1. In other words, the intermediate portion 171c is defined by a side wall 171c1 having a diameter d11 and a side wall 171c2 having a diameter d12, and the width w1 is (d12-d11) / 2. Furthermore, as the depth from the light-receiving surface to the intermediate portion 171c increases, the diameter of the intermediate portion 171c, i.e., the diameters d11 and d12, increases. On the other hand, the width w1 can remain constant regardless of the depth of the intermediate portion 171c. Also, in the cross-sectional view of Figure 7, the portion of the semiconductor layer 110 surrounded by the side wall 171c1 is conical, and the apex 110a of the cone is located deeper than the light-receiving surface of the semiconductor layer 110.

[0045] In the cross-sectional view of Figure 7, the trench 171 extends diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110. The bottom 171b faces the opening 171a. The angle α between the direction of the trench 171 from the opening 171a to the bottom 171b and the light-receiving surface of the semiconductor layer 110 may be less than 90 degrees, but can be arbitrarily determined depending on the material of the filling member described later and the wavelength of the incident light. The distance from the light-receiving surface of the semiconductor layer 110 to the bottom 171b of the trench 171, i.e., the depth, may be 0.1 μm to 0.6 μm.

[0046] A filler member 1711 is formed within the trench 171. The filler member 1711 contains a material having different optical properties (e.g., refractive index) than the semiconductor layer 110 located around the trench 171, and may be a dielectric material such as silicon oxide (SiO2) or silicon nitride (Si3N4). The process used to form the pixel separation portion 120 can be used to fill the filler member 1711. The filler member 1711 does not necessarily need to fill the entire trench 171. For example, as shown in Figure 9A, the filler member 1711 may be placed only in a part of the trench 171, and the rest of the trench 171 may be an empty space 1712. Alternatively, as shown in Figure 9B, the entire trench 171 may be an empty space 1712. Since the refractive index of the void 1712 is lower than that of the filler material 1711, incident light passing through the void 1712 has a different optical path within the semiconductor layer 110 compared to incident light passing through the filler material 1711. This difference in the optical path of the incident light increases the difference in refractive index in the trench 171, and thus increases the phase difference of the incident light. This increases the diffraction effect of the incident light within the semiconductor layer 110, improving the sensitivity to the incident light.

[0047] The trench 171 according to this embodiment can be formed by performing anisotropic etching on the semiconductor layer 110. Specifically, the sensor substrate 1 including the semiconductor layer 110 is adsorbed onto the mounting stage of the etching apparatus, and anisotropic etching is performed with the mounting stage tilted. The angle α can be adjusted by changing the tilt angle of the mounting stage during etching. The mounting stage is rotated during etching, and the trench 171 shown in Figures 7, 8A to 8C can be formed.

[0048] As described above, the trench 171 in this embodiment extends diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110. Therefore, light incident on the semiconductor layer 110 can be scattered and refracted multiple times by the trench 171. If we assume that the trench is formed perpendicular to the light-receiving surface, the incident light will only be refracted once. In this case, it would be difficult to increase the absorption efficiency of the incident light in the semiconductor layer 110 and improve sensitivity. On the other hand, in this embodiment, the trench 171 extends diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110. Therefore, light incident on the semiconductor layer 110 is scattered and refracted multiple times by the trench 171, making it possible to increase the light absorption efficiency in the semiconductor layer 110 and improve sensitivity. This effect is particularly noticeable with long-wavelength light. Furthermore, since a filler member 1711 having different properties from the semiconductor layer 110 is placed inside the trench, scattering and refraction become greater, making it possible to further increase the photoelectric conversion efficiency.

[0049] [Second Embodiment] Figure 10 is a cross-sectional view of the uneven structure according to this embodiment. In the first embodiment, the opening 171a of the trench 171 in plan view is circular, but the shape of the opening 171a is not limited to a circle. For example, as shown in Figure 10, the top portion 110a of the semiconductor layer 110 may be exposed at the opening 171a, and the opening 171a may be formed in an annular shape. For example, the top portion 110a of the semiconductor layer 110 in the first embodiment can be exposed at the opening 171a by polishing the light-receiving surface of the semiconductor layer 110 by chemical mechanical polishing (CMP) or the like. This embodiment also makes it possible to improve the sensitivity of the pixel 10 to incident light, similar to the first embodiment.

[0050] [Third Embodiment] A third embodiment of the present invention will now be described. The following embodiment will focus on configurations that differ from the first and second embodiments. Figure 11 is a cross-sectional view of the uneven structure according to this embodiment. Figures 12A to 12C are plan views of the uneven structure of Figure 11 along lines A-A', B-B', and C-C', respectively.

[0051] The uneven structure 170 includes a trench 172 that extends diagonally into the interior of the semiconductor layer 110 from the light-receiving surface of the semiconductor layer 110. The trench 172 includes an opening 172a, a bottom 172b, and an intermediate section 172c. A filling member 1721 is formed inside the trench 172. In the plan view of Figure 12A, the opening 172a is circular with a diameter d2. In the plan views of Figures 12B and 12C, the intermediate section 172c of the trench 172 constitutes an annular section with a width w2. That is, the intermediate section 172c is defined by a side wall 172c1 with a diameter d21 and a side wall 172c2 with a diameter d22, and the width w2 is (d22-d21) / 2. Furthermore, as the depth from the light-receiving surface to the intermediate section 172c increases, the diameter of the intermediate section 172c, i.e., the diameters d21 and d22, increase. The width w2 of the trench 172 in the plane along the line C-C' shown in Figure 12C is smaller than the width w2 of the trench 172 in the plane along the line B-B'. The width w2 narrows as the depth of the intermediate section 172c increases, and in cross-sectional view, the bottom 172b of the trench 172 is tapered.

[0052] In this embodiment as well, the trench 172 extends diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110. This makes it possible to increase the light absorption efficiency in the semiconductor layer 110 and improve sensitivity.

[0053] [Fourth Embodiment] A fourth embodiment of the present invention will now be described. Figure 13 is a cross-sectional view of the uneven structure in this embodiment. Figures 14A to 14C are plan views of the uneven structure in Figure 13 along lines A-A', B-B', and C-C', respectively.

[0054] The uneven structure 170 includes a trench 173 that extends diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110. The trench 173 includes an opening 173a, a bottom 173b, and an intermediate section 173c. A filling member 1731 is formed inside the trench 173. In the plan view of Figure 14A, the opening 173a is rectangular, and the width w3 of the opening 173a is, for example, 0.2 μm or less, preferably 0.1 μm or less. In the plan views of Figures 14B and 14C, the shape of the intermediate section 173c of the trench 173 corresponds to the shape of the opening 173a and is a rectangle with a width w3. The shape of the intermediate section 173c is constant regardless of the depth of the intermediate section 173c. Note that the plan view shapes of the opening 173a, intermediate section 173c, and bottom 173b may be circular or polygons other than rectangles.

[0055] In this embodiment as well, since the trench 173 extends diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110, it is possible to increase the light absorption efficiency in the semiconductor layer 110 and improve sensitivity.

[0056] [Fifth Embodiment] A fifth embodiment of the present invention will now be described. Figure 15 is a cross-sectional view of the uneven structure according to this embodiment. Figures 16A to 16C are plan views of the uneven structure of Figure 15 along lines A-A', B-B', and C-C', respectively.

[0057] The uneven structure 170 includes a trench 174 that extends diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110. The trench 174 includes an opening 174a, a bottom 174b, and an intermediate section 174c. A filling member 1741 is formed inside the trench 174. In the plan view of Figure 16A, the opening 174a is a rectangle with a width w4. In the plan views of Figures 16B and 16C, the two intermediate sections 174c branch off from one opening 174a and extend into the interior of the semiconductor layer 110. That is, the two intermediate sections 174c share one opening 174a. The shape of the intermediate section 174c corresponds to the opening 174a, and the intermediate section 174c is a rectangle with a width w4, similar to the opening 174a. The shape of the intermediate section 174c is constant regardless of the depth of the intermediate section 174c. On the other hand, the two intermediate sections 174c are spaced further apart from each other as they are deeper than the light-receiving surface.

[0058] In this embodiment as well, the trench 174 extends diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110, thereby increasing the light absorption efficiency in the semiconductor layer 110 and improving sensitivity.

[0059] [Sixth Embodiment] A sixth embodiment of the present invention will now be described. Figure 17 is a cross-sectional view of the uneven structure according to this embodiment. Figures 18A to 18C are plan views of the uneven structure of Figure 17 along lines A-A', B-B', and C-C', respectively.

[0060] The uneven structure 170 includes trenches 175 that extend diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110, and the trenches 175 include an opening 175a, a bottom 175b, and an intermediate portion 175c. A filling member 1751 is formed inside the trenches 175. In this embodiment, unlike the fifth embodiment, four intermediate portions 175c share one opening 175a. The shape of the intermediate portions 175c corresponds to the shape of the opening 175a and is a rectangle with a width w5. The shape of the intermediate portions 175c is constant regardless of the depth of the intermediate portions 175c. On the other hand, the four intermediate portions 175c are spaced apart from each other as they deepen from the light-receiving surface.

[0061] In this embodiment as well, the trench 175 extends diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110, thereby increasing the light absorption efficiency in the semiconductor layer 110 and improving sensitivity. The number of intermediate portions 175c is not limited to four; more intermediate portions 175c may share a single opening 175a.

[0062] [Seventh Embodiment] The trenches according to the first to sixth embodiments described above can be arranged in any pattern on the light-receiving surface of the semiconductor layer 110 including the APD 11. For example, as shown in Figure 19A, a plurality of trenches 171 including the opening 171a according to the first embodiment can be arranged at equal intervals in the row and column directions of the light-receiving surface of the semiconductor layer 110 in a plan view. Also, as shown in Figure 19B, a plurality of trenches 171 can be arranged in a staggered pattern in the row or column direction in a plan view. The pattern of the plurality of trenches 171 may differ for each pixel. For example, as shown in Figure 19C, a plurality of trenches 171 can be arranged according to the pattern in Figure 19A for one of two pixels separated by the pixel separation unit 120, and a plurality of trenches 171 can be arranged according to the pattern in Figure 19B for the other pixel. Note that the trenches do not necessarily have to be arranged according to a regular pattern and may be arranged randomly.

[0063] [Eighth Embodiment] An eighth embodiment of the present invention will now be described. Figure 20 is a cross-sectional view of the uneven structure according to this embodiment. Figures 21A to 21C are plan views of the uneven structure of Figure 20 along lines A-A', B-B', and C-C', respectively.

[0064] The uneven structure 170 includes a trench 176 that extends diagonally from the light-receiving surface of the semiconductor layer 110 into the interior of the semiconductor layer 110. The trench 176 includes an opening 176a, a bottom 176b, and an intermediate portion 176c. A filling member 1761 is formed inside the trench 176. In the plan view of Figure 21A, the opening 176a has a long shape with widths w61 and w62. The width w61 is, for example, 0.2 μm or less, and preferably 0.1 μm or less. The width w62 of the opening 176a is larger than w61 and may correspond to, for example, the width of a pixel. In the plan views of Figures 21B and 21C, the shape of the intermediate portion 176c of the trench 176 corresponds to the shape of the opening 176a and has widths w61 and w62. The shape of the intermediate portion 176c is constant regardless of the depth of the intermediate portion 176c. The shape of the opening 176a may be an ellipse, or a polygon other than a rectangle.

[0065] The trenches according to this embodiment can be arranged in any pattern on the light-receiving surface of the semiconductor layer 110. For example, as shown in Figure 22A, a plurality of trenches 176 can be arranged in the row direction of the light-receiving surface of the semiconductor layer 110 in a plan view. Alternatively, as shown in Figure 22B, for example, a plurality of trenches 176 can be arranged in a grid pattern in the row and column directions of the light-receiving surface of the semiconductor layer 110 in a plan view.

[0066] [Ninth Embodiment] A ninth embodiment of the present invention will now be described. The trenches shown in the above-described embodiments may be arranged in different patterns for each pixel. Figure 23 is a cross-sectional view of the uneven structure according to this embodiment. Each of the pixels 10A, 10B, and 10C has a semiconductor layer 110 and an insulating layer 140. A pixel separation portion 120 is formed between the pixels 10A, 10B, and 10C. A light-shielding portion 150 is formed between the pixel separation portion 120 and the insulating layer 140.

[0067] Trenches 177A, 177B, and 177C according to the present invention are formed on the light-receiving surfaces of pixels 10A, 10B, and 10C, respectively. In a cross-sectional view, trenches 177A, 177B, and 177C have trench lengths L1, L2, and L3, respectively. Trench length L2 is greater than L1, and trench length L3 is greater than L1 and L2. By changing the depth to which the trenches are formed for each pixel, as in this embodiment, the light absorption efficiency can be optimized for each pixel according to the wavelength band of the incident light and the material of the material filling the trenches 177A, 177B, and 177C.

[0068] [Tenth Embodiment] A tenth embodiment of the present invention will now be described. Figure 24 is a cross-sectional view of the uneven structure according to this embodiment. Each of the pixels 10A, 10B, and 10C has a semiconductor layer 110 and an insulating layer 140. A pixel separation portion 120 is formed between the pixels 10A, 10B, and 10C. A light-shielding portion 150 is formed between the pixel separation portion 120 and the insulating layer 140.

[0069] Trenches 178A, 178B, and 178C according to the present invention are formed on the light-receiving surfaces of pixels 10A, 10B, and 10C, respectively. The trenches 178A, 178B, and 178C extend between themselves and the light-receiving surface of the semiconductor layer 110 at angles α1, α2, and α3, respectively. Angle α2 is greater than angle α1, and angle α3 is greater than angles α1 and α2. By changing the angle between the trench and the light-receiving surface for each pixel, as in this embodiment, the light absorption efficiency can be optimized for each pixel according to the wavelength band of the incident light and the material of the material filling the trenches 178A, 178B, and 178C.

[0070] [Embodiment No. 11] An eleventh embodiment of the present invention will now be described. Figure 25 is a cross-sectional view of the uneven structure according to this embodiment. Each of the pixels 10A, 10B, and 10C has a semiconductor layer 110 and an insulating layer 140. A pixel separation portion 120 is formed between the pixels 10A, 10B, and 10C. A light-shielding portion 150 is formed between the pixel separation portion 120 and the insulating layer 140.

[0071] Trenches 179 according to the present invention are formed on the light-receiving surfaces of pixels 10A, 10B, and 10C, respectively. Pixel 10C has more trenches 179 than pixels 10A and 10B. Similarly, pixel 10A has more trenches 179 than pixel 10B. By changing the number of trenches formed for each pixel, as in this embodiment, the light absorption efficiency can be optimized for each pixel according to the wavelength band of the incident light and the material of the component filling the trenches 179.

[0072] In the example shown in Figure 25, the trenches 179 were formed on the light-receiving surfaces of pixels 10A, 10B, and 10C. However, as shown in Figure 26, for example, the trenches 179 may be formed only on the first surface of the semiconductor layer 110 of pixel 10A. In the example shown in Figure 26, pixel 10A may be a pixel that detects long-wavelength light with relatively low light absorption efficiency.

[0073] [Twelfth Embodiment] In the embodiment described above, the trenches are formed in the semiconductor layer 110, but the trenches do not necessarily have to be formed in the semiconductor layer 110. Figure 27 is a cross-sectional view of a plurality of adjacent pixels in this embodiment. As shown in Figure 27, the pixel 10 includes a semiconductor layer 110 and an insulating layer 140. A surface of the insulating layer 140 on the side to which light is incident has an uneven structure 180 including trenches 181. The shape of the trenches 181, the material that fills them, the optical properties, etc., may be the same as any of the trenches 171 to 179 described above. In this embodiment as well, it is possible to increase the absorption efficiency of incident light and improve sensitivity.

[0074] [13th Embodiment] Figure 28 is a block diagram of the imaging system in this embodiment. The photoelectric conversion device in the above-described embodiment is applicable to various imaging systems. Examples of imaging systems include digital still cameras, digital camcorders, camera heads, photocopiers, fax machines, mobile phones, in-vehicle cameras, observation satellites, and surveillance cameras. Figure 28 shows a block diagram of a digital still camera as an example of an imaging system.

[0075] The imaging system 7 includes a barrier 706, a lens 702, an aperture 704, an imaging device 70, a signal processing unit 708, a timing generation unit 720, an overall control / calculation unit 718, a memory unit 710, a recording medium control I / F unit 716, a recording medium 714, and an external I / F unit 712. The barrier 706 protects the lens, and the lens 702 forms an optical image of the subject on the imaging device 70. The aperture 704 varies the amount of light passing through the lens 702. The imaging device 70 is configured as a photoelectric converter in the above embodiment and converts the optical image formed by the lens 702 into image data. The signal processing unit 708 performs various corrections and data compression on the imaging data output from the imaging device 70.

[0076] The timing generation unit 720 outputs various timing signals to the imaging device 70 and the signal processing unit 708. The overall control / calculation unit 718 controls the entire digital still camera, and the memory unit 710 temporarily stores image data. The recording medium control I / F unit 716 is an interface for recording or reading image data to or from the recording medium 714, which is a removable recording medium such as a semiconductor memory for recording or reading imaging data. The external I / F unit 712 is an interface for communicating with an external computer or the like. Timing signals and the like may be input from outside the imaging system, and the imaging system only needs to have at least the imaging device 70 and the signal processing unit 708 that processes the image signals output from the imaging device 70.

[0077] In this embodiment, the imaging device 70 and the signal processing unit 708 are provided on separate semiconductor substrates, but the imaging device 70 and the signal processing unit 708 may be formed on the same semiconductor substrate.

[0078] Furthermore, each pixel includes a first photoelectric conversion unit and a second photoelectric conversion unit. The signal processing unit 708 processes the pixel signal based on the charge generated in the first photoelectric conversion unit and the pixel signal based on the charge generated in the second photoelectric conversion unit, and can acquire distance information from the imaging device 70 to the subject.

[0079] [14th Embodiment] Figure 29 is a diagram of the light detection system in this embodiment, and is a block diagram of a distance image sensor using the photoelectric conversion device described in the above embodiment.

[0080] As shown in Figure 29, the distance image sensor 401 comprises an optical system 402, a photoelectric converter 403, an image processing circuit 404, a monitor 405, and a memory 406. The distance image sensor 401 receives light (modulated light, pulsed light) that is emitted from the light source device 411 toward the subject and reflected from the surface of the subject. Based on the time from emission to reception, the distance image sensor 401 can acquire a distance image corresponding to the distance to the subject.

[0081] The optical system 402 includes one or more lenses and guides the image light (incident light) from the subject to the photoelectric converter 403, where it forms an image on the light-receiving surface (sensor part) of the photoelectric converter 403.

[0082] The photoelectric converter 403 can be any of the photoelectric converters described in the above-described embodiments. The photoelectric converter 403 supplies a distance signal indicating the distance obtained from the received light signal to the image processing circuit 404.

[0083] The image processing circuit 404 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric converter 403. The distance image (image data) obtained through image processing can be displayed on the monitor 405 and stored (recorded) in the memory 406.

[0084] The distance image sensor 401 configured in this way can acquire more accurate distance images by applying the photoelectric conversion device described above, as the characteristics of the pixels are improved.

[0085] [15th Embodiment] The technology described herein can be applied to a variety of products. For example, the technology described herein may be applied to an endoscopic surgical system.

[0086] Figure 30 is a schematic diagram of the endoscopic surgical system in this embodiment. Figure 30 shows a surgeon (physician) 1131 performing surgery on a patient 1132 on a patient bed 1133 using the endoscopic surgical system 1103. As shown in the figure, the endoscopic surgical system 1103 includes an endoscope 1100, surgical instruments 1110, and a cart 1134 on which various devices for endoscopic surgery are mounted.

[0087] The endoscope 1100 comprises a barrel 1101, the tip of which is inserted into the body cavity of the patient 1132 for a predetermined length, a camera head 1102 connected to the base end of the barrel 1101, and an arm 1121. Figure 30 shows the endoscope 1100 configured as a so-called rigid endoscope having a rigid barrel 1101, but the endoscope 1100 may also be configured as a so-called flexible endoscope having a flexible barrel.

[0088] An opening into which an objective lens is fitted is provided at the tip of the endoscope tube 1101. A light source device 1203 is connected to the endoscope 1100, and the light generated by the light source device 1203 is guided to the tip of the endoscope tube by a light guide extending inside the endoscope tube 1101, and is irradiated through the objective lens towards the object to be observed inside the body cavity of the patient 1132. The endoscope 1100 may be a straight-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0089] The camera head 1102 contains an optical system and a photoelectric converter. Reflected light from the object being observed (observation light) is focused by the optical system into the photoelectric converter. The photoelectric converter converts the observation light into electrical signals, generating an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The photoelectric converter can be any of the photoelectric converters described in the embodiments described above. The image signal is transmitted as RAW data to the camera control unit (CCU) 1135.

[0090] The CCU1135 consists of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operation of the endoscope 1100 and the display device 1136. Furthermore, the CCU1135 receives image signals from the camera head 1102 and performs various image processing operations on these image signals, such as development processing (demosaic processing), to display images based on the image signals.

[0091] The display device 1136 displays an image based on an image signal that has been processed by the CCU 1135, under control from the CCU 1135.

[0092] The light source device 1203 is equipped with a light source such as an LED (Light Emitting Diode) and supplies illumination light to the endoscope 1100 when photographing the surgical area, etc.

[0093] The input device 1137 is an input interface for the endoscopic surgical system 1103. The user can input various types of information and instructions to the endoscopic surgical system 1103 via the input device 1137.

[0094] The treatment instrument control device 1138 controls the driving of the energy treatment instrument 1112 for purposes such as tissue cauterization, incision, or blood vessel sealing.

[0095] The light source device 1203 is capable of supplying illumination light to the endoscope 1100 when photographing the surgical area, and may be, for example, an LED, a laser light source, or a white light source consisting of a combination thereof. When a white light source is configured by a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision. Therefore, the white balance of the captured image can be adjusted in the light source device 1203. In this case, the laser light from each of the RGB laser light sources may be irradiated onto the observation target in a time-division manner, and the drive of the image sensor of the camera head 1102 may be controlled in synchronization with the irradiation timing. This makes it possible to capture images corresponding to each of the RGB colors in a time-division manner. With this method, a color image can be obtained without providing a color filter on the image sensor.

[0096] Furthermore, the drive of the light source device 1203 may be controlled so that the intensity of the light output from the light source device 1203 is changed at predetermined time intervals. By controlling the drive of the image sensor of the camera head 1102 in synchronization with the timing of the change in light intensity to acquire images in time division and combining these images, it is possible to generate a high dynamic range image without so-called black crushing and white clipping.

[0097] Furthermore, the light source device 1203 may be configured to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, the wavelength dependence of light absorption in body tissue can be utilized. Specifically, by irradiating with narrowband light compared to the irradiation light used during normal observation (i.e., white light), predetermined tissues such as blood vessels on the surface of mucosa can be imaged with high contrast. Alternatively, in special light observation, fluorescence observation may be performed to obtain an image from fluorescence generated by irradiation with excitation light. In fluorescence observation, excitation light can be irradiated onto body tissue and fluorescence from the body tissue can be observed, or a reagent such as indocyanine green (ICG) can be injected into body tissue and excitation light corresponding to the fluorescence wavelength of the reagent can be irradiated onto the body tissue to obtain a fluorescence image. The light source device 1203 may be configured to supply narrowband light and / or excitation light corresponding to such special light observation.

[0098] [16th Embodiment] The light detection system and mobile body of this embodiment will be described with reference to Figures 31A, 31B, and 32. In this embodiment, an example of an in-vehicle camera is shown as the light detection system.

[0099] Figure 31A is a schematic diagram of the photodetection system in this embodiment, showing an example of a vehicle system and a photodetection system mounted on the vehicle system. The photodetection system 1301 includes a photoelectric converter 1302, an image preprocessing unit 1315, an integrated circuit 1303, and an optical system 1314. The optical system 1314 forms an optical image of the subject on the photoelectric converter 1302. The photoelectric converter 1302 converts the optical image of the subject formed by the optical system 1314 into an electrical signal. The photoelectric converter 1302 is one of the photoelectric converters in each of the embodiments described above. The image preprocessing unit 1315 performs predetermined signal processing on the signal output from the photoelectric converter 1302. The functions of the image preprocessing unit 1315 may be incorporated into the photoelectric converter 1302. The photodetection system 1301 is provided with at least two sets of optical systems 1314, photoelectric converters 1302, and image preprocessing units 1315, and the output from each set of image preprocessing units 1315 is input to the integrated circuit 1303.

[0100] The integrated circuit 1303 is an integrated circuit for imaging system applications and includes an image processing unit 1304 with a storage medium 1305, an optical distance measuring unit 1306, a parallax calculation unit 1307, an object recognition unit 1308, and an anomaly detection unit 1309. The image processing unit 1304 performs image processing such as development and defect correction on the output signal of the image preprocessing unit 1315. The storage medium 1305 stores the primary storage of the captured image and the defect positions of the captured pixels. The optical distance measuring unit 1306 focuses on the subject and measures the distance. The parallax calculation unit 1307 calculates distance measurement information from multiple image data acquired by multiple photoelectric converters 1302. The object recognition unit 1308 recognizes subjects such as cars, roads, signs, and people. When the anomaly detection unit 1309 detects an anomaly in the photoelectric converter 1302, it alerts the main control unit 1313 to the anomaly.

[0101] The integrated circuit 1303 may be implemented by specially designed hardware, by a software module, or by a combination of these. It may also be implemented by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or a combination of these.

[0102] The main control unit 1313 coordinates and controls the operation of the light detection system 1301, vehicle sensor 1310, control unit 1320, etc. Alternatively, the main control unit 1313 may be omitted, and the light detection system 1301, vehicle sensor 1310, and control unit 1320 may each have their own communication interfaces, and each may send and receive control signals via a communication network, for example, using the CAN standard.

[0103] The integrated circuit 1303 has the function of receiving control signals from the main control unit 1313 or transmitting control signals and set values ​​to the photoelectric converter 1302 via its own control unit.

[0104] The light detection system 1301 is connected to the vehicle sensor 1310 and can detect the vehicle's driving conditions, such as vehicle speed, yaw rate, and steering angle, as well as the external environment and the status of other vehicles and obstacles. The vehicle sensor 1310 also functions as a distance information acquisition unit, acquiring distance information to objects. Furthermore, the light detection system 1301 is connected to the driver assistance control unit 1311, which performs various driving assistance functions such as automatic steering, automatic cruising, and collision avoidance. In particular, regarding the collision judgment function, the system determines whether a collision with another vehicle or obstacle has occurred and estimates the collision based on the detection results of the light detection system 1301 and the vehicle sensor 1310. This enables avoidance control when a collision is estimated and activation of safety devices in the event of a collision.

[0105] Furthermore, the light detection system 1301 is also connected to a warning device 1312 that issues a warning to the driver based on the judgment result of the collision judgment unit. For example, if the collision judgment unit determines that there is a high probability of collision, the main control unit 1313 performs vehicle control such as applying the brakes, releasing the accelerator, and suppressing engine output to avoid a collision or mitigate damage. The warning device 1312 issues a warning to the user by means of emitting a sound or other warning, displaying warning information on display screens such as the car navigation system and meter panel, and applying vibration to the seat belt and steering wheel.

[0106] The light detection system 1301 in this embodiment is capable of capturing images of the area around the vehicle, for example, the front or rear. Figure 31B is a schematic diagram of a moving object in this embodiment, showing a configuration in which the front of the vehicle is imaged by the light detection system 1301.

[0107] The two photoelectric converters 1302 are positioned in front of the vehicle 1300. Specifically, it is preferable that the center line of the vehicle 1300 with respect to its direction of movement or external shape (e.g., vehicle width) is considered as the axis of symmetry, and the two photoelectric converters 1302 are positioned symmetrically with respect to the axis of symmetry. This makes it possible to effectively acquire distance information between the vehicle 1300 and the object being photographed and to determine the possibility of collision. Furthermore, it is preferable that the photoelectric converters 1302 are positioned so as not to obstruct the driver's field of view when the driver is viewing the situation outside the vehicle 1300 from the driver's seat. The warning device 1312 is preferably positioned so as to be easily visible to the driver.

[0108] Next, the fault detection operation of the photoelectric converter 1302 in the photodetection system 1301 will be explained using Figure 32. Figure 32 is a flowchart showing the operation of the photodetection system in this embodiment. The fault detection operation of the photoelectric converter 1302 can be performed according to steps S1410 to S1480.

[0109] In step S1410, the startup settings for the photoelectric converter 1302 are performed. Specifically, setting information for the operation of the photoelectric converter 1302 is transmitted from outside the photodetection system 1301 (for example, from the main control unit 1313) or from inside the photodetection system 1301, and the photoelectric converter 1302 starts the imaging operation and fault detection operation.

[0110] Next, in step S1420, the photoelectric converter 1302 acquires a pixel signal from the active pixels. Also, in step S1430, the photoelectric converter 1302 acquires an output value from a fault detection pixel provided for fault detection. This fault detection pixel is equipped with a photoelectric conversion element, just like the active pixels. A predetermined voltage is written to this photoelectric conversion element. The fault detection pixel outputs a signal corresponding to the voltage written to this photoelectric conversion element. Note that steps S1420 and S1430 may be executed in the reverse order.

[0111] Next, in step S1440, the light detection system 1301 determines 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 matching determination in step S1440 shows that the expected output value and the actual output value match, the light detection system 1301 proceeds to step S1450, determines that the imaging operation is being performed normally, and proceeds to step S1460. In step S1460, the light detection system 1301 transmits the pixel signals of the scan row to the storage medium 1305 for temporary storage. After that, the light detection system 1301 returns to step S1420 and continues the fault detection operation. On the other hand, if the result of the matching determination in step S1440 shows that the expected output value and the actual output value do not match, the light detection system 1301 proceeds to step S1470. In step S1470, the light detection system 1301 determines that there is an abnormality in the imaging operation and issues an alarm to the main control unit 1313 or the alarm device 1312. The alarm device 1312 displays that an abnormality has been detected on its display unit. Subsequently, in step S1480, the light detection system 1301 stops the photoelectric converter 1302 and terminates the operation of the light detection system 1301.

[0112] In this embodiment, an example is shown where the flowchart is looped every row, but the flowchart may be looped every multiple rows, or the fault detection operation may be performed every frame. The alarm in step S1470 may be notified to an external party via a wireless network.

[0113] Furthermore, although this embodiment describes control to avoid collisions with other vehicles, it can also be applied to control that automatically follows other vehicles or control that automatically drives without deviating from the lane. In addition, the light detection system 1301 can be applied not only to vehicles such as the vehicle itself, but also to moving objects (mobile devices) such as ships, aircraft, or industrial robots. Moreover, it can be applied not only to moving objects, but also to a wide range of devices that utilize object recognition, such as intelligent transportation systems (ITS). The photoelectric conversion device of the present invention may further be configured to acquire various types of information, such as distance information.

[0114] [17th Embodiment] Figure 33(a) shows a specific example of an electronic device in this embodiment, and shows eyeglasses 1600 (smart glasses). The eyeglasses 1600 are equipped with the photoelectric converter 1602 described in each of the embodiments above. A display device including a light-emitting device such as an OLED or LED may be provided on the back side of the lens 1601. There may be one or more photoelectric converters 1602. In addition, multiple types of photoelectric converters may be combined. The arrangement position of the photoelectric converter 1602 is not limited to that shown in Figure 33(a).

[0115] The eyeglasses 1600 further include a control device 1603. The control device 1603 functions as a power source that supplies power to the photoelectric converter 1602 and the aforementioned display device. The control device 1603 also controls the operation of the photoelectric converter 1602 and the display device. The lens 1601 has an optical system formed therein for focusing light onto the photoelectric converter 1602.

[0116] Figure 33(b) shows eyeglasses 1610 (smart glasses) relating to one application example. The eyeglasses 1610 have a control device 1612, which is equipped with a photoelectric converter corresponding to a photoelectric converter 1602 and a display device. The lens 1611 has an optical system formed therein for projecting the photoelectric converter in the control device 1612 and the light emitted from the display device, and an image is projected onto the lens 1611. The control device 1612 functions as a power supply that supplies power to the photoelectric converter and the display device, and also controls the operation of the photoelectric converter and the display device. The control device 1612 may have a gaze detection unit that detects the wearer's gaze. Gaze detection may use infrared light. The infrared light emitter emits infrared light towards the eyeball of the user who is gazing at the displayed image. An imaging unit having a light-receiving element detects the reflected light from the eyeball of the emitted infrared light, thereby obtaining an image of the eyeball. By having a reduction mechanism that reduces the amount of light transmitted from the infrared light-emitting part to the display part in a planar view, the degradation of image quality is reduced.

[0117] The user's gaze towards a displayed image is detected from an image of the eyeball obtained by imaging with infrared light. Any known method can be applied to gaze detection using an image of the eyeball. As an example, a gaze detection method based on the Purkinje image obtained by the reflection of the irradiated light from the cornea can be used.

[0118] More specifically, gaze detection processing is performed based on the pupil-corneal reflection method. Using the pupil-corneal reflection method, a gaze vector representing the orientation (rotation angle) of the eyeball is calculated based on the pupil image and Purkinje image contained in the captured image of the eyeball, thereby detecting the user's gaze.

[0119] The display device of this embodiment includes a photoelectric converter having a light-receiving element, and may control the display image of the display device based on the user's gaze information from the photoelectric converter.

[0120] Specifically, the display device determines, based on gaze information, a first field of view area that the user is fixated on and a second field of view area other than the first field of view area. The first and second field of view areas may be determined by the control device of the display device or by an external control device. Within the display area of ​​the display device, the display resolution of the first field of view area may be controlled to be higher than that of the second field of view area. In other words, the resolution of the second field of view area may be lower than that of the first field of view area.

[0121] Furthermore, the display area may include a first display area and a second display area different from the first display area. Based on line-of-sight information, a higher priority area may be determined from the first and second display areas. The first and second field-of-sight areas may be determined by the control device of the display device or by an external control device. The resolution of the higher priority area may be controlled to be higher than the resolution of the areas other than the higher priority area. In other words, the resolution of areas with relatively lower priority may be lower.

[0122] Artificial Intelligence (AI) may be used in determining the first field of view area and the area with the highest priority. The AI ​​may be a model configured to estimate the angle of gaze and the distance to the target object at the end of the line of sight from the image of the eyeball, using the image of the eyeball and the direction the eyeball was actually looking in the image as training data. The AI ​​program may be installed in the display device, the photoelectric converter, or an external device. If the external device has the AI ​​program, it may be transmitted to the display device from a server or the like via communication.

[0123] When display control is performed based on visual detection, this embodiment can be preferably applied to smart glasses further having a photoelectric converter for capturing images of the outside. The smart glasses can display the captured external information in real time.

[0124] [Other embodiments] The present invention is not limited to the embodiments described above and can be modified in various ways. For example, an example in which a part of the configuration of one embodiment is added to another embodiment, or in which a part of the configuration of another embodiment is replaced, is also an embodiment of the present invention.

[0125] The disclosures in this specification include the following components: (Composition 1) A photoelectric conversion device comprising multiple pixels formed on a substrate, A pixel separation section is provided between multiple adjacent pixels, The uneven structure formed on the light-receiving surface of the substrate and Equipped with, The aforementioned uneven structure includes trenches that extend diagonally from the light-receiving surface into the interior of the substrate. The trench contains a material different from the substrate located around the trench. Photoelectric converter. (Configuration 2) A photoelectric conversion device comprising multiple pixels formed on a substrate, A pixel separation section is provided between multiple adjacent pixels, The uneven structure formed on the light-receiving surface of the substrate and Equipped with, The aforementioned uneven structure includes trenches that extend diagonally from the light-receiving surface into the interior of the substrate. The trench contains a material having a different refractive index than the substrate located around the trench. Photoelectric converter. (Composition 3) The trench includes an annular portion that forms an annular shape in a cross-section parallel to the light-receiving surface, The diameter of the annular portion increases as the depth from the light-receiving surface to the annular portion increases. A photoelectric conversion device as described in configuration 1 or 2. (Composition 4) The width of the annular portion is constant regardless of the depth from the light-receiving surface to the annular portion. The photoelectric conversion device described in configuration 3. (Composition 5) The width of the annular portion narrows as the depth from the light-receiving surface to the annular portion increases. The photoelectric conversion device described in configuration 3. (Composition 6) The trench has a circular opening in a plan view of the light-receiving surface. A photoelectric conversion device according to any one of configurations 1 to 5. (Composition 7) The photoelectric conversion device according to configuration 6, wherein a plurality of the openings are arranged in a row and column direction in a plan view of the light-receiving surface, or are arranged in a staggered pattern in either the row or column direction in a plan view of the light-receiving surface. (Composition 8) The trench comprises an opening in the light-receiving surface, a bottom facing the opening, and an intermediate portion between the opening and the bottom. The shape of the intermediate portion corresponds to the shape of the opening. A photoelectric conversion device as described in configuration 1 or 2. (Composition 9) The opening is rectangular or circular in a plan view of the light-receiving surface. The photoelectric conversion device described in configuration 8. (Composition 10) The opening is formed in a grid pattern in a plan view of the light-receiving surface. The photoelectric conversion device described in configuration 8. (Composition 11) Multiple trenches share one opening. A photoelectric conversion device according to any one of items 8 to 10 of the configuration. (Composition 12) The multiple intermediate portions are spaced apart from each other as the depth from the light-receiving surface increases. A photoelectric conversion device according to any one of items 8 to 11 of the configuration. (Composition 13) The photoelectric conversion device according to configuration 8 or 9, wherein a plurality of the openings are arranged in a row and column direction in a plan view of the light-receiving surface, or are arranged in a staggered pattern in either the row or column direction in a plan view of the light-receiving surface. (Composition 14) The trench is formed in the semiconductor layer of the substrate, the photoelectric conversion device according to any one of configurations 1 to 13. (Composition 15) The photoelectric conversion device according to any one of configurations 1 to 13, wherein the trench is formed in the insulating layer of the substrate. (Composition 16) The photoelectric conversion device according to any one of configurations 1 to 15, wherein the trench contains a void. (Composition 17) A photoelectric conversion device according to any one of configurations 1 to 16, which is a back-illuminated type photoelectric conversion device. (Composition 18) A photoelectric converter of the SPAD type, as described in any one of configurations 1 to 17. (Composition 19) An imaging device including a photoelectric converter as described in any one of items 1 to 18, A signal processing unit that processes imaging data output from the imaging device, An imaging system equipped with the following features. (Composition 20) It is a mobile object, A photoelectric conversion device as described in any one of items 1 to 18, A distance information acquisition unit acquires distance information to an object from the signal output from the aforementioned photoelectric converter, A control unit that controls the moving body based on the distance information, A mobile body characterized by having the following features.

[0126] The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by a process in which one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0127] It should be noted that the embodiments described above are merely examples of how the present invention can be implemented, and the technical scope of the present invention should not be interpreted as being limited by them. In other words, the present invention can be implemented in various ways without departing from its technical concept or its main features. [Explanation of symbols]

[0128] 10 pixels 11 APD 110 Semiconductor layer 140 Insulating layer 120-pixel separation section 170 Uneven structure 171 Trench 1711 Filling material

Claims

1. A photoelectric conversion device comprising multiple pixels formed on a substrate, A pixel separation section is provided between multiple adjacent pixels, The uneven structure formed on the light-receiving surface of the substrate and Equipped with, The aforementioned uneven structure includes trenches that extend diagonally from the light-receiving surface into the interior of the substrate. The trench contains a material different from the substrate located around the trench. The trench includes an annular portion that forms an annular shape in a cross-section parallel to the light-receiving surface, The diameter of the annular portion increases as the depth from the light-receiving surface increases. The width of the annular portion is the same at a first depth and a second depth that is different from the first depth, from the light-receiving surface. Photoelectric converter.

2. A photoelectric conversion device comprising multiple pixels formed on a substrate, A pixel separation section is provided between multiple adjacent pixels, The uneven structure formed on the light-receiving surface of the substrate and Equipped with, The aforementioned uneven structure includes trenches that extend diagonally from the light-receiving surface into the interior of the substrate. The trench contains a material having a different refractive index than the substrate located around the trench. The trench includes an annular portion that forms an annular shape in a cross-section parallel to the light-receiving surface, The diameter of the annular portion increases as the depth from the light-receiving surface increases. The width of the annular portion is the same at a first depth and a second depth that is different from the first depth, from the light-receiving surface. Photoelectric converter.

3. The trench includes an annular portion that forms an annular shape in a cross-section parallel to the light-receiving surface, The diameter of the annular portion increases as the depth from the light-receiving surface increases. The photoelectric conversion device according to claim 1 or 2.

4. The width of the annular portion is constant regardless of the depth from the light-receiving surface to the annular portion. The photoelectric conversion device according to claim 3.

5. The trench has a circular opening in a plan view of the light-receiving surface. The photoelectric conversion device according to claim 1 or 2.

6. The photoelectric conversion device according to claim 5, wherein a plurality of the openings are arranged in a row and column direction in a plan view of the light-receiving surface, or are arranged in a staggered pattern in either the row or column direction in a plan view of the light-receiving surface.

7. The trench comprises one opening in the light-receiving surface, The opening is circular in a plan view of the light-receiving surface. The photoelectric conversion device according to claim 1 or 2.

8. A photoelectric conversion device comprising a plurality of pixels formed on a substrate, A pixel separation section is provided between multiple adjacent pixels, The uneven structure formed on the light-receiving surface of the substrate and Equipped with, The aforementioned uneven structure includes trenches that extend diagonally from the light-receiving surface into the interior of the substrate. The trench contains a material different from the substrate located around the trench. The trench comprises an opening in the light-receiving surface, a bottom facing the opening, and an intermediate portion between the opening and the bottom. The shape of the intermediate portion and the shape of the opening are formed in a grid pattern. Photoelectric converter.

9. A photoelectric conversion device comprising a plurality of pixels formed on a substrate, A pixel separation section is provided between multiple adjacent pixels, The uneven structure formed on the light-receiving surface of the substrate and Equipped with, The aforementioned uneven structure includes trenches that extend diagonally from the light-receiving surface into the interior of the substrate. The trench contains a material having a different refractive index than the substrate located around the trench. The trench comprises an opening in the light-receiving surface, a bottom facing the opening, and an intermediate portion between the opening and the bottom. The shape of the intermediate portion and the shape of the opening are formed in a grid pattern. Photoelectric converter.

10. Multiple trenches share one opening. The photoelectric conversion device according to claim 7.

11. The trench comprises a bottom facing the opening and an intermediate portion between the opening and the bottom, The multiple intermediate portions are spaced apart from each other as the depth from the light-receiving surface increases. The photoelectric conversion device according to claim 7.

12. The photoelectric conversion device according to claim 7, wherein a plurality of the openings are arranged in a row and column direction in a plan view of the light-receiving surface, or are arranged in a staggered pattern in either the row or column direction in a plan view of the light-receiving surface.

13. The photoelectric conversion device according to claim 1 or 2, wherein the substrate has a semiconductor layer including the light-receiving surface, and the trench is formed in the semiconductor layer.

14. The photoelectric conversion device according to claim 1 or 2, wherein the substrate has an insulating layer including the light-receiving surface, and the trench is formed in the insulating layer.

15. The photoelectric conversion device according to claim 1 or 2, wherein the trench contains a void.

16. The photoelectric conversion device according to claim 1 or 2, which is a back-illuminated type photoelectric conversion device.

17. The photoelectric converter according to claim 1 or 2, which is a SPAD type photoelectric converter.

18. An imaging device including the photoelectric conversion device described in claim 1 or 2, A signal processing unit that processes imaging data output from the imaging device, An imaging system equipped with the following features.

19. It is a mobile object, A photoelectric conversion device according to claim 1 or 2, A distance information acquisition unit acquires distance information to an object from the signal output from the aforementioned photoelectric converter, A control unit that controls the moving body based on the distance information, A mobile body characterized by having the following features.

Images