Avalanche diode, pixel wafer, optical detector and control method thereof

Abstract

The invention provides an avalanche diode, a pixel wafer, an optical detector and a control method thereof, relates to the field of integrated circuits, and aims to improve the detection effect of a single-photon avalanche diode in a strong light scene. The avalanche diode comprises a substrate, a first electrode, a second electrode and an isolation part, the substrate has a first doping type, and the substrate comprises a first surface and a second surface which are opposite to each other in a first direction; the first direction is the thickness direction of the substrate; the first electrode has a first doping type, and the first electrode extends into the substrate from the first surface; the second electrode has a second doping type, the second electrode extends into the substrate from the first surface, and the second electrode and the first electrode are arranged at an interval; the isolation part extends from the first surface to the second surface; the isolation part is configured to receive a first voltage signal, and the voltage of the first voltage signal is adjustable.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuits, and particularly to an avalanche diode, a pixel wafer, a photodetector, a control method thereof, and a computer-readable storage medium. Background Art

[0002] A single-photon avalanche diode is a highly sensitive photodetector. With its unique avalanche effect and picosecond-level time resolution, it plays an important role in fields such as quantum optics, lidar, and biomedical imaging.

[0003] The detection efficiency is an important parameter for measuring the performance of a single-photon avalanche diode. In low-light scenarios, it is necessary to improve the detection efficiency of the single-photon avalanche diode to enhance the detection effect, and in high-light scenarios, it is necessary to reduce the detection efficiency of the single-photon avalanche diode to alleviate light intensity saturation. However, currently, traditional single-photon avalanche diode detectors are difficult to simultaneously meet the requirements of high detection efficiency in low light and low detection efficiency in high light. Summary of the Invention

[0004] Embodiments of the present invention provide an avalanche diode, a pixel wafer, a photodetector, a control method thereof, and a computer-readable storage medium, aiming to improve the detection effect of the single-photon avalanche diode in high-light scenarios on the premise of ensuring the low-light detection effect.

[0005] To achieve the above object, the embodiments of the present invention adopt the following technical solutions: In a first aspect, an avalanche diode is provided, including a substrate, a first electrode, a second electrode, and an isolation part. The substrate has a first doping type and includes a first surface and a second surface that face away from each other in a first direction. The first direction is the thickness direction of the substrate. The first electrode has a first doping type and extends from the first surface into the substrate. The second electrode has a second doping type and extends from the first surface into the substrate and is spaced apart from the first electrode. The isolation part extends from the first surface to the second surface and surrounds the first electrode and the second electrode. The isolation part is configured to receive a first voltage signal, and the voltage of the first voltage signal is adjustable.

[0006] The isolation part provided by the avalanche diode provided by the above solution of the present application extends from the first surface to the second surface and surrounds the electrodes, which can effectively separate adjacent avalanche diodes and suppress signal crosstalk. The isolation part being configured to receive an adjustable first voltage signal means that the avalanche diode can dynamically adjust the electric field strength of the depletion region in different scenarios, and the electric field strength of the depletion region can affect the detection efficiency of the avalanche diode. In high-light scenarios, by adjusting the first voltage signal, the detection efficiency of the avalanche diode is reduced, thereby increasing the upper limit of the detectable light intensity of the single-photon avalanche diode and enhancing the detection effect in high-light scenarios.

[0007] As a possible implementation, the substrate includes an epitaxial layer and a first well region provided on one side of the epitaxial layer along a first direction. The surface of the first well region away from the epitaxial layer is a first surface. The first well region has a first doping type, and a first electrode and a second electrode are embedded in the first well region. The side surface of the isolation portion contacts the side surface of the first electrode and the side surface of the first well region.

[0008] As a possible implementation, the isolation portion includes an isolation portion main body and an insulating layer covering the isolation portion main body. The insulating layer is located between the side surface of the isolation portion main body and the side surface of the epitaxial layer, and between the side surface of the isolation portion main body and the side surface of the first well region. A part of the side surface of the isolation portion main body contacts the side surface of the first electrode.

[0009] In the above implementation, the present application arranges the isolation portion main body to contact the first electrode, so that the isolation portion main body applied with the first voltage signal cooperates with the first electrode to form an electric field, and further adjusts the detection efficiency of the avalanche diode through the electric field. At the same time, the insulating layer is arranged between the isolation portion main body and the epitaxial layer and the first well region, which can effectively avoid the influence of the epitaxial layer and the first well region on the first voltage signal and improve the stability of signal transmission.

[0010] As a possible implementation, the substrate further includes a second well region. The second well region is embedded in the first well region, and the second well region has a second doping type. The second electrode is embedded in the second well region, and the first well region fills the gap between the second well region and the first electrode.

[0011] In the above implementation, the second electrode is arranged in the second well region. At the same time, the second well region is embedded in the first well region, and the second electrode and the second well region are set to have the same doping type, so that the electric field direction of the edge breakdown between the second electrode and the first well region can be regulated through the second well region, thereby increasing the avalanche breakdown probability.

[0012] As a possible implementation, the substrate further includes a third well region. The third well region is provided on the side of the epitaxial layer away from the first well region, and the third well region has a first doping type. The side surface of the isolation portion also contacts the side surface of the third well region.

[0013] As a possible implementation, the second electrode is configured to receive a cathode voltage signal, and the cathode voltage signal is adjustable.

[0014] In the above implementation, by configuring the second electrode to receive an adjustable cathode voltage signal, when adjusting the detection efficiency of the avalanche diode, not only can the avalanche diode be adjusted through the first voltage signal, but also the detection efficiency of the avalanche diode can be adjusted through the cathode voltage signal, improving the flexibility and versatility of the avalanche diode.

[0015] In a second aspect, an embodiment of the present application further provides a pixel wafer, which includes a plurality of avalanche diodes as provided in the first aspect. The effects achievable by the pixel wafer can refer to the beneficial effects of the avalanche diodes provided in the first aspect above, and will not be elaborated here.

[0016] As a possible implementation, the pixel wafer further includes a first connection layer disposed on one side of the second surface of the substrates of the plurality of avalanche diodes along a first direction. A first metal grid is provided in the first connection layer, and the first metal grid is connected to one end of the isolation portion in the avalanche diode close to the connection layer. The first metal grid is used to receive a first voltage signal and transmit the first voltage signal to the isolation portion.

[0017] In the above implementation, the first connection layer provided by the pixel wafer is provided with a first metal grid in the partition portion. Based on the conductivity of the metal, it is convenient for the avalanche diode to be connected to the outside and signal transmission through the first metal grid. And because of the grid-like design, light is convenient to enter the second surface of the avalanche diode through the gaps on the first metal grid.

[0018] As a possible implementation, a conductive pad is further provided in the first connection layer, and the conductive pad and the first metal grid are insulated from each other; the pixel wafer further includes a second connection layer disposed on one side of the plurality of avalanche diodes away from the first connection layer; a first connection portion is provided in the second connection layer, and the first connection portion is connected to the first electrode of the avalanche diode; the pixel wafer further includes a first connection column extending along the first direction; both ends of the first connection column are respectively connected to the conductive pad and the first connection portion; the conductive pad is used to receive an anode voltage signal, and the first connection column and the first connection portion are used to transmit the anode voltage signal to the first electrode.

[0019] In the above implementation, the received anode voltage signal is transmitted to the first electrode through the conductive pad, the first connection column and the first connection portion, so as to supply power to the first electrode, which is convenient for subsequent adjustment of the avalanche diode according to the anode voltage signal received by the first electrode and the first voltage signal, and at the same time ensures power supply to the avalanche diode.

[0020] As a possible implementation, a second connection portion is further provided in the second connection layer, the second connection portion is connected to the second electrode of the avalanche diode, and the second connection portion and the first connection portion are insulated from each other; the second connection portion is used to receive a cathode voltage signal and transmit the cathode voltage signal to the second electrode. In the above implementation, the cathode voltage signal is received through the second connection portion, which ensures power supply to the avalanche diode. At the same time, the second connection portion and the first connection portion are insulated from each other to avoid mutual interference between the anode voltage signal and the cathode voltage signal.

[0021] In a third aspect, an embodiment of the present application further provides a photodetector, including a pixel wafer and a logic wafer. The photodetector is configured to be connected to a control circuit. The pixel wafer is connected to the logic wafer, and the logic wafer is configured to: obtain the number of photons detected by the pixel wafer within a set period, and send the number of photons to the control circuit. The control circuit is configured to: in the case where the number of photons is less than or equal to a first set threshold, send a first voltage signal with a first voltage value to an isolation part in the pixel wafer. In the case where the number of photons is greater than the first set threshold, send a first voltage signal with a second voltage value to the isolation part. Wherein both the first voltage value and the second voltage value are negative values, and the absolute value of the first voltage value is greater than the absolute value of the second voltage value.

[0022] The photodetector provided by the present application includes a pixel wafer and a logic wafer. The logic wafer can send the number of photons detected by the pixel wafer to the control circuit, and then the control circuit analyzes and judges the number of photons, so as to confirm the current light intensity, and further sends different voltage signals to the isolation part according to the light intensity, so as to adjust the detection efficiency of the pixel wafer.

[0023] As a possible implementation, the logic wafer is further configured to: in the case where the number of photons is greater than the first set threshold and less than or equal to a second set threshold, send a cathode voltage signal with a third voltage value to a second electrode in the pixel wafer. In the case where the number of photons is greater than the second set threshold, send a cathode voltage signal with a fourth voltage value to the second electrode. Wherein, the second set threshold is greater than the first set threshold, both the third voltage value and the fourth voltage value are positive values, and the third voltage value is greater than the fourth voltage value.

[0024] In the above implementation, the logic wafer further judges the number of photons to judge the current light intensity. When the number of photons is greater than the first set threshold, it further judges the relationship between the number of photons and the second set threshold, and further sends different cathode voltage signals according to the light intensity, so as to adjust the detection efficiency of the pixel wafer.

[0025] As a possible implementation, the logic wafer is further configured to: in the case where the number of photons is less than or equal to the first set threshold, send a cathode voltage signal with a fifth voltage value to the second electrode. Wherein, the fifth voltage value is a positive value, and the fifth voltage value is greater than the fourth voltage value.

[0026] In the above implementation, the logic wafer can also judge whether the number of photons is too small, and further send a larger cathode voltage signal according to the light intensity, so as to increase the voltage difference between the cathode and the anode of the avalanche diode, and further adjust the detection efficiency of the pixel wafer.

[0027] As a possible implementation, the fifth voltage value is equal to the third voltage value.

[0028] In a fourth aspect, the present application further provides a control method for a photodetector, which is applied to the photodetector as in the third aspect. The control method includes obtaining the number of photons detected by the pixel wafer in the photodetector within a set period. When the number of photons is less than or equal to a first set threshold, a first voltage signal with a first voltage value is sent to the isolation part in the pixel wafer. When the number of photons is greater than the first set threshold, a first voltage signal with a second voltage value is sent to the isolation part. Wherein, both the first voltage value and the second voltage value are negative values, and the absolute value of the first voltage value is greater than the absolute value of the second voltage value.

[0029] As a possible implementation, when the number of photons is greater than the first set threshold, sending a first voltage signal with a second voltage value to the isolation part includes: when the number of photons is greater than the first set threshold and less than or equal to a second set threshold, sending a cathode voltage signal with a third voltage value to the second electrode in the pixel wafer. When the number of photons is greater than the second set threshold, sending a cathode voltage signal with a fourth voltage value to the second electrode. Wherein, the second set threshold is greater than the first set threshold, both the third voltage value and the fourth voltage value are positive values, and the third voltage value is greater than the fourth voltage value.

[0030] In a fifth aspect, an embodiment of the present application further provides a computer-readable storage medium. The computer-readable storage medium stores computer program instructions, and when the computer program instructions are run by a processor, one or more steps in the control method as in the fourth aspect are executed.

[0031] Wherein, the beneficial effects of the fourth aspect and the fifth aspect can refer to the beneficial effects of the first aspect, and will not be elaborated here. Description of the Drawings

[0032] Figure 1 It is a schematic diagram of an avalanche diode provided by an embodiment of the present application; Figure 2 It is a schematic diagram of another avalanche diode provided by an embodiment of the present application; Figure 3 It is a well region distribution diagram of an avalanche diode provided by an embodiment of the present application; Figure 4 It is a well region distribution diagram of another avalanche diode provided by an embodiment of the present application; Figure 5 It is a well region distribution diagram of another avalanche diode provided by an embodiment of the present application; Figure 6 It is a schematic diagram of a pixel wafer provided by an embodiment of the present application; Figure 7Schematic diagram of a photodetector provided by an embodiment of the present application; Figure 8 Schematic diagram of an equivalent circuit for adjusting a photodetector provided by an embodiment of the present application; Figure 9 Schematic diagram of a control method for a photodetector provided by an embodiment of the present application; Figure 10 Schematic diagram of an electronic device provided by an embodiment of the present application. Detailed implementation manners

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] The terms "first" and "second" are only used for descriptive purposes, and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0035] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. In addition, when describing pipelines, the terms "connected" and "coupled" used in the present invention have the meaning of conducting. The specific meaning needs to be understood in combination with the context.

[0036] In the embodiments of the present invention, words such as "exemplary" or "for example" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present invention should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Exactly, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0037] A single photon avalanche diode (SPAD) is a photoelectric detection device based on the avalanche multiplication effect. With its high sensitivity and fast response characteristics, SPAD has become a key technology in multiple cutting-edge fields. The core of SPAD is the avalanche multiplication effect. When a photon is absorbed, electron-hole pairs are generated in the device. These carriers are accelerated by a strong electric field and collide with the lattice, generating more electron-hole pairs, thus forming an avalanche signal.

[0038] The detection efficiency is an important parameter for measuring the performance of a single photon avalanche diode. In low-light scenarios, it is necessary to improve the detection efficiency of the single photon avalanche diode to enhance the detection effect. In high-light scenarios, it is necessary to reduce the detection efficiency of the single photon avalanche diode to increase the upper limit of the detectable light intensity and improve the detection effect. However, currently, traditional single photon avalanche diodes have a relatively high detection efficiency under high-light conditions, which can cause a large number of photons to trigger avalanches simultaneously, making it impossible to distinguish individual photon events in the output signal. Moreover, high light may keep the SPAD continuously saturated, resulting in the inability to respond to continuously arriving photons, affecting the detection effect of grayscale or depth information.

[0039] In view of this, the present application provides an avalanche diode. Exemplarily, as Figure 1 shown. The avalanche diode 100 includes a substrate 1, a first electrode 2, a second electrode 3, and an isolation part 4. The substrate 1 has a first doping type and includes a first surface 11 and a second surface 12 that face away from each other in a first direction X. The first direction X is the thickness direction of the substrate 1, that is, the direction opposite to the first surface 11 and the second surface 12. The first electrode 2 has a first doping type and extends from the first surface 11 into the substrate 1. The second electrode 3 has a second doping type and extends from the first surface 11 into the substrate 1, and is spaced apart from the first electrode 2. The isolation part 4 extends from the first surface 11 to the second surface 12 and surrounds the first electrode 2 and the second electrode 3. The isolation part 4 is configured to receive a first voltage signal, and the voltage of the first voltage signal is adjustable.

[0040] In the embodiments of the present application, the material of the substrate 1 may be a silicon wafer, or germanium, etc., which is not limited herein. The substrate 1 includes a first surface 11 and a second surface 12, and the two may be substantially parallel, that is, the two are arranged in parallel, and may include partial non-parallelism of the two surfaces due to processing errors. The first surface 11 may be the front surface of the substrate 1, and the second surface 12 is the back surface of the substrate 1. Therefore, when the second surface 12 is the light incident surface, the avalanche diode 100 is a back-illuminated structure, thereby improving the geometric fill factor and detection efficiency of the device. Of course, the present application does not limit the above structure. The first electrode 2 has a first doping type, that is, impurity ions are doped into the first electrode 2 to form, for example, the ion conduction type of the doped ions is N-type or P-type, and the second electrode 3 has a second doping type, which means that the doping type is different from that of the first electrode 2.

[0041] In some embodiments, an oxide dielectric layer 10 is further provided on the second surface 12. As a possible implementation manner, the material of the oxide dielectric layer 10 includes silicon oxide, silicon nitride, etc. that are transparent to visible light and near-infrared. The highly transparent oxide dielectric layer 10 can enable visible light and near-infrared to penetrate through the second surface 12 and irradiate into the substrate 1.

[0042] The isolation part 4 provided by the avalanche diode 100 provided by the present application extends from the first surface 11 to the second surface 12 and surrounds the electrodes. The isolation part 4 is configured to receive an adjustable first voltage signal, which means that the avalanche diode 100 can dynamically adjust the electric field strength of the depletion region in different scenarios, and the electric field strength of the depletion region can affect the detection efficiency of the avalanche diode 100. In a strong light scenario, by adjusting the first voltage signal, the detection efficiency of the avalanche diode 100 is reduced, thereby improving the detection effect of the single-photon avalanche diode 100 in a strong light scenario.

[0043] In some embodiments, the substrate 1 includes an epitaxial layer 13 and a first well region 14 provided on one side of the epitaxial layer 13 along the first direction X. The surface of the first well region 14 away from the epitaxial layer 13 is the first surface 11. The first well region 14 has a first doping type, and the first electrode 2 and the second electrode 3 are embedded in the first well region 14. The side surface of the isolation part 4 is in contact with the side surface of the first electrode 2 and the side surface of the first well region 14.

[0044] In the embodiments of the present application, the first doping type is taken as an example of P-type doping, that is, the substrate 1 is taken as a P-type epitaxial piece (P-EPI). A P-type single-crystalline silicon, that is, a P-type epitaxial layer 13, is grown on the surface of the silicon wafer. P-type elements, such as non-metallic boron (B) atoms, are lightly doped on the epitaxial layer 13 to form the first well region 14. Above the first well region 14, a higher-concentration N-type element, such as non-metallic phosphorus (P) or metal arsenic (As), is doped to form the second electrode 3, which can form a main junction with the first well region 14 having the first doping type.

[0045] As a possible implementation, the first well region 14 is a reverse doping structure, that is, the doping concentration decreases in the direction from the second surface 12 to the first surface 11, and the first well region 14 has the largest doping concentration on the surface away from the first surface 11. The reverse doping peak and the doping concentration level are designed according to the actual application, and the voltage of the edge breakdown is reasonably controlled, so that the carriers generated on both sides of the substrate 1 can drift to the avalanche region, and a detection device that completely relies on edge breakdown is obtained.

[0046] By adjusting the first voltage signal received by the isolation part 4, it is equivalent to connecting a metal-oxide-semiconductor capacitor in parallel on the basis of the avalanche diode 100. One end of the capacitor is the isolation part 4 of the avalanche diode 100, and the other end of the capacitor is the epitaxial layer 13 of the avalanche diode 100. When the voltage at one end of the capacitor changes, that is, the first voltage signal received by the isolation part 4 changes, the other end of the capacitor will generate equal and opposite charges, and the formed electric field will change, thereby affecting the distribution of the avalanche breakdown probability and ultimately affecting the detection efficiency. As a possible implementation method, the second electrode is configured to receive a cathode voltage signal, and the cathode voltage signal is adjustable. The avalanche diode 100 operates under reverse bias. By adjusting the cathode voltage signal, the reverse over-bias of the avalanche diode 100 can be adjusted, thereby affecting the detection efficiency of the avalanche diode 100.

[0047] As a possible implementation, for example, refer to Figure 2 The isolation part 4 includes an isolation part body 41 and an insulating layer 42, such as an oxide dielectric layer, covering the isolation part body 41. The insulating layer 42 is located between the side surface of the isolation part body 41 and the side surface of the epitaxial layer 13, and between the side surface of the isolation part body 41 and the side surface of the first well region 14. Part of the side surface of the isolation part body 41 contacts the side surface of the first electrode 2.

[0048] In some embodiments, reference Figure 1 , the substrate 1 further includes a second well region 15. The second well region 15 is embedded in the first well region 14, and the second well region 15 has a second doping type. The second electrode 3 is embedded in the second well region 15, and the first well region 14 fills the gap between the second well region 15 and the first electrode 2. In this embodiment, the second well region 15 is formed on the basis of the substrate 1 by doping an element of the same type as the second electrode 3, but the doping concentration is lower than the doping concentration of the second electrode 3, which is a lightly doped type. For example, when the second electrode 3 is N+, the second well region 15 is an N-type well.

[0049] The second well region 15 can regulate the electric field direction of the edge breakdown of the first well region 14 and the second electrode 3, so that the electric field direction is mainly toward the direction after the combination of the edge and the bottom of the substrate 1, which can more conveniently drive the photo-generated carriers to gradually drift from both sides of the second surface 12 to the second well region 15, thereby increasing the avalanche breakdown probability and improving the detection efficiency.

[0050] In some embodiments, referring to Figure 1 , the substrate 1 further includes a third well region 16. The third well region 16 is disposed on a side of the epitaxial layer 13 away from the first well region 14, and the third well region 16 has a first doping type. The side surface of the isolation portion 4 is also in contact with the side surface of the third well region 16.

[0051] Exemplarily, as Figure 3 , Figure 4 and Figure 5 shown, the embodiments of the present application also provide a variety of well region distribution diagrams of the avalanche diode 100. Figure 3 , Figure 4 and Figure 5 are all cross-sectional views of the avalanche diode 100. Figure 3 The first electrode 2 in Figure 4 is in the shape of a square ring, Figure 5 the shape of the first electrode 2 in

[0052] is the result of subtracting an inscribed circle from a square,

[0053] The embodiments of the present application also provide an avalanche diode 100 including doping ions and concentration ranges. In some embodiments, the insulating layer 42 is made of a high dielectric constant material, such as alumina, tantalum oxide, etc. The trench of the isolation portion 4 is filled with tungsten or copper. The doping ions of the second electrode 3 are at least one of P, As, or Sb, and the doping concentration is greater than or equal to 1e19 cm-3. The doping ions of the first electrode 2 are at least one of B, Al, Ga, or In, and the doping concentration is greater than or equal to 1e19 cm-3. The doping ions of the epitaxial layer 13 are at least one of B, Al, Ga, or In, and the doping concentration is less than or equal to ≤1e15 cm-3. The doping ions of the first well region 14 are at least one of B, Al, Ga, or In, and the peak doping concentration is 5e15 - 1e17 cm-3. The doping ions of the second well region 15 are at least one of P, As, or Sb, and the doping concentration is 5e15 - 1e17 cm-3. The doping ions of the third well region 16 are at least one of B, Al, Ga, or In, and the doping concentration is 1e17 - 1e19 cm-3.

[0053] The embodiments of the present application also provide a pixel wafer including a plurality of avalanche diodes 100 as described above. Exemplarily, as Figure 6As shown, a plurality of avalanche diodes 100 are isolated by the isolation part 4. As a possible implementation, the isolation part 4 in the embodiments of the present application adopts a deep trench full-through design.

[0054] In some embodiments, by way of example, as Figure 6 shown, the pixel wafer 200 further includes a first connection layer 5 disposed on one side of the second surface 12 of the substrates of the plurality of avalanche diodes 100 along the first direction X. The first connection layer 5 is provided with a first metal grid 51, and the first metal grid 51 is connected to one end of the isolation part 4 in the avalanche diode 100 close to the first connection layer 5. The first metal grid 51 is used to receive a first voltage signal and transmit the first voltage signal to the isolation part 4.

[0055] In the above embodiments, the first metal grid 51 located in the partition part is provided in the first connection layer 5 provided by the pixel wafer 200 provided by the present application. Based on the conductivity of the metal, it is convenient for the avalanche diode 100 to be connected to the outside and transmit signals through the first metal grid 51. And because of the grid design, light is more convenient to pass through the gaps on the first metal grid 51 and enter the isolation part 4 from the second surface 12.

[0056] In some embodiments, the first connection layer 5 is further provided with a conductive pad 53, and the conductive pad 53 and the first metal grid 51 are insulated from each other. The conductive pad 53 is used to receive an anode voltage signal.

[0057] The pixel wafer further includes a second connection layer 6 disposed on the side of the plurality of avalanche diodes 100 away from the first connection layer 5. The second connection layer 6 is provided with a first connection portion 61, and the first connection portion 61 is connected to the first electrode 2 of the avalanche diode 100. The first electrodes 2 of the plurality of avalanche diodes 100 in the pixel wafer can be all connected to the first connection portion 61 and thus led out through the first connection portion 61 uniformly.

[0058] The pixel wafer 200 further includes a first connection post 52 extending along the first direction X. For example, the pixel wafer includes a dielectric layer surrounding each avalanche diode 100, and the first connection post 52 can be disposed in the dielectric layer and penetrate through the dielectric layer along the first direction X. Both ends of the first connection post 52 are respectively connected to the conductive pad 53 and the first connection portion 61, thereby realizing the leading-out of the first electrode 2 of the avalanche diode 100. The first connection post 52 and the first connection portion 61 are used to transmit the anode voltage signal to the first electrode 2.

[0059] In the above embodiment, the received anode voltage signal is transmitted to the first electrode 2 through the conductive pad 53, the first connecting column 52 and the first connecting portion 61, so as to realize power supply for the first electrode 2, and then facilitate the subsequent adjustment of the avalanche diode 100 according to the anode voltage signal and the first voltage signal received by the first electrode 2, while ensuring the power supply for the avalanche diode 100.

[0060] In some embodiments, the second connection layer 6 is further provided with a second connection portion 62, which is connected to the second electrode 3 of the avalanche diode 100 to realize the extraction of the second electrode 3 of the avalanche diode 100. The second connection portion 62 and the first connection portion 61 are formed in the same film layer (i.e., the second connection layer 6), but the two are insulated from each other; the second connection portion 62 is used to receive the cathode voltage signal and transmit the cathode voltage signal to the second electrode 3.

[0061] In the above embodiment, the cathode voltage signal is received by the second connection part 62, which ensures that the avalanche diode 100 is powered. At the same time, the second connection part 62 and the first connection part 61 are insulated from each other to avoid mutual interference between the anode voltage signal and the cathode voltage signal. As a possible implementation method, the first metal grid 51 is a metal structure, and the first metal grid 51 is connected to the isolation part 4 in the avalanche diode near one end of the first connection layer 5. Since the pixel wafer 200 includes a plurality of avalanche diodes 100, the isolation part 4 of each avalanche diode 100 is connected to the corresponding first metal grid 51, and the plurality of first metal grids 51 form a metal mesh for receiving the first voltage signal.

[0062] As a possible implementation method, a vertical through hole is etched on a silicon wafer and filled with an electrical connection structure formed by a conductive material (such as copper, tungsten, etc.), that is, a first connection column 52 is formed. One end of the first connection column 52 is connected to the conductive pad 53, and the other end is connected to the first electrode 2, which can transmit the anode voltage signal to the first electrode 2 as a bridge. The second connection portion 61 is connected to the second electrode 3 of the avalanche diode 100, and can transmit the cathode voltage signal to the second electrode 3. The first electrode 2 receives the anode voltage signal, and the second electrode 3 receives the cathode voltage signal, which means that the reverse over-bias of the avalanche diode 100 in the pixel wafer 200 will be adjusted. In conjunction with the adjustment of the first voltage signal obtained by the isolation portion 4, the dynamic adjustment range of the detection efficiency of the avalanche diode 100 will be greatly improved, thereby adapting to detection in strong light scenarios.

[0063] In some embodiments, for example, Figure 7 As shown, combined with Figure 6, an embodiment of the present application also provides a photodetector 500, and the photodetector 500 includes the pixel wafer and the logic wafer as described above. The pixel wafer 200 is connected to the logic wafer 300, and the photodetector 500 is connected to the control circuit 400. The logic wafer 300 is configured to: obtain the number of photons detected by the pixel wafer 200 within a set period, and send the number of photons to the control circuit 400.

[0064] As a possible implementation, the pixel wafer 200 and the logic wafer 300 are connected through a 3D stacking process. The second electrode 3 of the avalanche diode 100 is connected to the quenching circuit of the logic wafer through bonding, such as Cu-Cu bonding.

[0065] The control circuit 400 is configured to: in the case where the number of photons is less than or equal to the first set threshold, send a first voltage signal with a first voltage value to the isolation part 4 in the pixel wafer. In the case where the number of photons is greater than the first set threshold, send a first voltage signal with a second voltage value to the isolation part 4. Wherein both the first voltage value and the second voltage value are negative values, and the absolute value of the first voltage value is greater than the absolute value of the second voltage value.

[0066] The logic wafer 300 is further configured to: in the case where the number of photons is greater than the first set threshold and less than or equal to the second set threshold, send a cathode voltage signal with a third voltage value to the second electrode 3 in the pixel wafer 200. In the case where the number of photons is greater than the second set threshold, send a cathode voltage signal with a fourth voltage value to the second electrode 3. Wherein, the second set threshold is greater than the first set threshold, both the third voltage value and the fourth voltage value are positive values, and the third voltage value is greater than the fourth voltage value.

[0067] Refer to Figure 8 , Figure 8 FIG. is a schematic diagram of an equivalent circuit adjusted for the photodetector 500. As a possible implementation, the second voltage value is -BV, the absolute value of the second voltage value is the breakdown voltage value BV of the avalanche diode 100, the absolute value of the first voltage value is two volts more than the absolute value of the second voltage value, that is, the first voltage value is -(BV + 2V) in this implementation, the third voltage value is 3.3V, and the fourth voltage value is 1.5V. The first set threshold and the second set threshold are set for the photodetector provided in the embodiment of the present application to distinguish the usage scenarios of the photodetector. In a strong light scenario, strong light means more photons incident on the avalanche diode 100, and the pixel is likely to be in an avalanche state continuously, and it is necessary to reduce the detection efficiency of the photodetector. On the contrary, in a non-strong light scenario, fewer photons will be incident on the avalanche diode 100.

[0068] See back Figure 8, the logic wafer 300 can detect the number of photons detected by the pixel wafer within a certain period of time. When the number of photons is less than or equal to the first set threshold, it means that the number of photons reaching the surface of the avalanche diode 100 per unit time is small and the light is normal. When the number of photons is greater than the first set threshold and less than or equal to the second set threshold, it means that the number of photons reaching the surface of the avalanche diode 100 per unit time is large, and it is necessary to reduce the detection efficiency of the photodetector 500. When the number of photons is greater than the second set threshold, it means that the number of photons reaching the surface of the avalanche diode 100 per unit time is very large, and compared with the situation where the number of photons is greater than the first set threshold and less than or equal to the second set threshold, it is necessary to further reduce the detection efficiency of the photodetector 500.

[0069] The avalanche diode 100 operates under reverse bias conditions, and the difference between the cathode potential and the anode potential of the avalanche diode 100 should be greater than the breakdown voltage BV of the avalanche diode 100. Under normal operating conditions, when the voltage VDTI received by the isolation part of the avalanche diode 100 is higher than or equal to the anode voltage VAnode of the avalanche diode 100, the MOS capacitor formed by the isolation part and the epitaxial layer will generate an electric field opposite to the anode and cathode of the avalanche diode 100. Under the action of the opposite electric field, the photo-generated carriers generated outside the avalanche diode 100 are difficult to be effectively transported to the avalanche region to trigger avalanche. Therefore, the avalanche breakdown probability will be compressed and the detection efficiency of the avalanche diode 100 will also be reduced. When the voltage VDTI received by the isolation part of the avalanche diode 100 is lower than the anode voltage VAnode of the avalanche diode 100, the MOS capacitor formed by the isolation part and the epitaxial layer will generate an electric field in the same direction as the anode and cathode of the avalanche diode 100, which will promote the more effective transport of the photo-generated carriers generated outside the avalanche diode 100 to the avalanche region to trigger avalanche. Therefore, the avalanche breakdown probability distribution will expand, thereby improving the detection efficiency of the avalanche diode 100.

[0070] Therefore, when the number of photons is greater than the first set threshold, in order to reduce the detection efficiency, the first voltage signal will be adjusted and the first voltage value will be adjusted to the second voltage value. Since both the first voltage value and the second voltage value are negative values, and the absolute value of the first voltage value is greater than the absolute value of the second voltage value, the MOS capacitor formed by the isolation part and the epitaxial layer will generate an electric field opposite to the anode and cathode of the avalanche diode 100 to compress the avalanche breakdown probability.

[0071] When the number of photons is greater than the first set threshold, it can be further divided into two cases. The first case is that the number of photons is greater than the first set threshold and less than or equal to the second set threshold. In this case, only the isolation part voltage needs to be adjusted, corresponding to Figure 8For the case of medium and low detection efficiency. The second case is that the number of photons is greater than the second set threshold. In this case, on the basis of adjusting the isolation section voltage and using the MOS capacitor to generate an electric field opposite to that of the anode and cathode of the avalanche diode 100, by adjusting the cathode voltage, the reverse bias voltage is adjusted to reduce the electric field formed by the original electrodes. Both methods are used to reduce the detection efficiency of the avalanche diode 100, corresponding to Figure 8 For the case of extremely low detection efficiency.

[0072] As a possible implementation, when the number of photons is less than or equal to the first set threshold, corresponding to Figure 8 For the case of medium and high detection efficiency. Send a cathode voltage signal with a fifth voltage value to the second electrode. Among them, the fifth voltage value is positive, and the fifth voltage value is greater than the fourth voltage value. As a possible implementation, the fifth voltage value is equal to the third voltage value of 3.3V.

[0073] The embodiment of the present application also provides a control method for a photodetector, which is applied to the photodetector as described above. Exemplarily, as Figure 9 shown, the control method includes: S1: Obtain the number of photons detected by the pixel wafer in the photodetector within a set period.

[0074] S2: Judge the magnitude relationship between the number of photons and the set threshold.

[0075] Step S2 includes two cases S21 and S22. Among them, S21: When the number of photons is less than or equal to the first set threshold, send a first voltage signal with a first voltage value to the isolation section in the pixel wafer. S22: When the number of photons is greater than the first set threshold, send a first voltage signal with a second voltage value to the isolation section. Among them, the first voltage value and the second voltage value are both negative, and the absolute value of the first voltage value is greater than the absolute value of the second voltage value.

[0076] Further, step S22 further includes: S221: When the number of photons is greater than the first set threshold and less than or equal to the second set threshold, send a cathode voltage signal with a third voltage value to the second electrode in the pixel wafer.

[0077] S222: When the number of photons is greater than the second set threshold, send a cathode voltage signal with a fourth voltage value to the second electrode. Among them, the second set threshold is greater than the first set threshold, the third voltage value and the fourth voltage value are both positive, and the third voltage value is greater than the fourth voltage value.

[0078] Embodiments of the present application further provide a computer-readable storage medium and an electronic device. The computer-readable storage medium stores computer program instructions, and when the computer program instructions are run by a processor, one or more steps in the above control method are executed. Exemplarily, as Figure 10 shown, the electronic device 020 may include a first processor 021, a communication line 022, and a communication interface 023.

[0079] Exemplarily, the electronic device 020 may further include a memory 024. Among them, the first processor 021, the memory 024, and the communication interface 023 may be connected through the communication line 022. Among them, the first processor 021 may be a central processing unit (CPU), a general-purpose processor, a digital signal processor (DSP), a microprocessor, a microcontroller, a programmable logic device, or any combination thereof. The first processor 021 may also be other devices with processing functions, such as circuits, devices, or software modules.

[0080] The communication line 022 is used to transmit information between the components of the electronic device 020.

[0081] The communication interface 023 is used to communicate with other devices or communication networks. The communication network may be an Ethernet, a radio access network (RAN), a wireless local area network (WLAN), etc. The communication interface 023 may be an interface circuit, a pin, a radio frequency module, a transceiver, or any device capable of implementing communication.

[0082] Memory 024 is used to store instructions. Among them, the instructions can be computer programs for executing the circuit manufacturing method provided in the embodiments of the present application. Among them, the memory 024 can be a read-only memory (ROM) or other types of static storage devices that can store static information and / or instructions, or a random access memory (RAM) or other types of dynamic storage devices that can store information and / or instructions. It can also be an electrically erasable programmable read-only memory (EEPROM), a compact cisc read-only memory (CD-ROM), or other optical disc storage, optical disc storage, magnetic disk storage media, or other magnetic storage devices. Optical disc storage includes compressed optical discs, laser discs, optical discs, digital versatile discs, or Blu-ray discs, etc.

[0083] It should be noted that the memory 024 can exist independently of the first processor 021 or be integrated with the first processor 021. The memory 024 can be used to store instructions, program codes, or some data, etc. The memory 024 can be located inside the electronic device 020 or outside the electronic device 020, without limitation. The first processor 021 is used to execute the instructions stored in the memory 024 to implement the circuit manufacturing method provided in the following embodiments of the present application.

[0084] In one example, the processor 021 can include one or more CPUs, such as Figure 10 CPU0 and CPU1 in

[0085] As an alternative implementation, the electronic device 020 includes multiple processors. For example, in addition to Figure 10 the first processor 021 in

[0086] As an alternative implementation, the electronic device 020 further includes an output device 025 and an input device 026. Exemplarily, the input device 026 can be a device such as a keyboard, a mouse, a microphone, or a joystick, and the output device 025 can be a device such as a display screen or a speaker. It should be noted that the electronic device 020 can be a desktop computer, a laptop computer, a network server, a mobile phone, a tablet computer, a wireless terminal, an embedded device, an integrated circuit system, or an electronic device with a Figure 10 similar structure in Figure 10 The shown composition structure in Figure 10In addition to the components shown, the electronic device 020 may include more or fewer components than those shown, or combine certain components, or have a different component arrangement.

[0087] Exemplarily, the electronic device 020 may be the above-mentioned light detector 500, or any device including the light detector 500.

[0088] After considering the specification and practicing the invention disclosed herein, those skilled in the art will readily conceive of other embodiments of the present application. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include known common general knowledge or conventional technical means in the technical field not disclosed in the present application.

[0089] Finally, it should be noted that the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An avalanche diode, characterized in that, Comprising: A substrate having a first doping type, the substrate including a first surface and a second surface facing away from each other in a first direction; The first direction is the thickness direction of the substrate; A first electrode having a first doping type, the first electrode extending from the first surface into the substrate; A second electrode having a second doping type, the second electrode extending from the first surface into the substrate and being spaced apart from the first electrode; An isolation portion, the isolation portion extending from the first surface to the second surface, the isolation portion surrounding the first electrode and the second electrode; the isolation portion is configured to receive a first voltage signal, and the voltage of the first voltage signal is adjustable.

2. The avalanche diode according to claim 1, wherein The substrate includes an epitaxial layer and a first well region provided on one side of the epitaxial layer along the first direction; The surface of the first well region away from the epitaxial layer is the first surface, the first well region has a first doping type, and the first electrode and the second electrode are embedded in the first well region; The side surface of the isolation portion contacts the side surface of the first electrode and the side surface of the first well region.

3. The avalanche diode according to claim 2, characterized in that, The isolation portion includes an isolation portion main body and an insulating layer covering the isolation portion main body; The insulating layer is located between the side surface of the isolation portion main body and the side surface of the epitaxial layer, and between the side surface of the isolation portion main body and the side surface of the first well region; A partial side surface of the isolation portion main body contacts the side surface of the first electrode.

4. The avalanche diode according to claim 2, characterized in that, The substrate further includes a second well region; The second well region is embedded in the first well region, and the second well region has the second doping type; The second electrode is embedded in the second well region, and the first well region fills the gap between the second well region and the first electrode.

5. The avalanche diode according to claim 2, characterized in that, The substrate further includes a third well region; The third well region is provided on a side of the epitaxial layer away from the first well region, and the third well region has a first doping type; The side surface of the isolation portion also contacts the side surface of the third well region.

6. The avalanche diode according to any one of claims 1 to 5, characterized in that The second electrode is configured to receive a cathode voltage signal, and the cathode voltage signal is adjustable.

7. A pixel wafer, characterized in that, Including a plurality of avalanche diodes according to any one of claims 1 to 6.

8. The pixel wafer according to claim 7, wherein, The pixel wafer further includes a first connection layer provided on one side of the second surface of the substrates of the plurality of avalanche diodes along the first direction; A first metal grid is provided in the first connection layer, and the first metal grid is connected to an end of the isolation portion in the avalanche diode close to the first connection layer; the first metal grid is used to receive the first voltage signal and transmit the first voltage signal to the isolation portion.

9. The pixel wafer according to claim 8, wherein A conductive pad is further provided in the first connection layer, and the conductive pad and the first metal grid are insulated from each other; The pixel wafer further includes a second connection layer provided on a side of the plurality of avalanche diodes away from the first connection layer; a first connection portion is provided in the second connection layer, and the first connection portion is connected to the first electrode of the avalanche diode; The pixel wafer further includes a first connection post, and the first connection post extends along the first direction; Both ends of the first connection column are respectively connected to the conductive gasket and the first connection part; The conductive gasket is used to receive the anode voltage signal, and the first connection column and the first connection part are used to transmit the anode voltage signal to the first electrode.

10. The pixel wafer according to claim 9, wherein A second connection part is further provided in the second connection layer. The second connection part is connected to the second electrode of the avalanche diode, and the second connection part and the first connection part are insulated from each other; the second connection part is used to receive the cathode voltage signal and transmit the cathode voltage signal to the second electrode.

11. A photodetector, characterized in that, It includes a pixel wafer and a logic wafer; the photodetector is configured to be connected to a control circuit; The pixel wafer is the pixel wafer according to any one of claims 7 to 10, and the pixel wafer is connected to the logic wafer; The logic wafer is configured to: obtain the number of photons detected by the pixel wafer within a set period and send the number of photons to the control circuit; The control circuit is configured to: in the case where the number of photons is less than or equal to a first set threshold, send a first voltage signal with a first voltage value to the isolation part in the pixel wafer; in the case where the number of photons is greater than the first set threshold, send a first voltage signal with a second voltage value to the isolation part; Wherein, both the first voltage value and the second voltage value are negative values, and the absolute value of the first voltage value is greater than the absolute value of the second voltage value.

12. The photodetector according to claim 11, wherein, The logic wafer is further configured to: In the case where the number of photons is greater than the first set threshold and less than or equal to a second set threshold, send a cathode voltage signal with a third voltage value to the second electrode in the pixel wafer; In the case where the number of photons is greater than the second set threshold, send a cathode voltage signal with a fourth voltage value to the second electrode; Wherein, the second set threshold is greater than the first set threshold, both the third voltage value and the fourth voltage value are positive values, and the third voltage value is greater than the fourth voltage value.

13. The photodetector according to claim 12, wherein The logic wafer is further configured to: in the case where the number of photons is less than or equal to the first set threshold, send a cathode voltage signal with a fifth voltage value to the second electrode; Wherein, the fifth voltage value is a positive value, and the absolute value of the fifth voltage value is greater than the absolute value of the fourth voltage value.

14. The photodetector according to claim 13, wherein The fifth voltage value is equal to the third voltage value.

15. A control method for a photodetector, characterized in that, Applied to the photodetector according to any one of claims 11 to 14, the control method includes: Obtain the number of photons detected by the pixel wafer in the photodetector within a set period; In the case where the number of photons is less than or equal to the first set threshold, send a first voltage signal with a first voltage value to the isolation part in the pixel wafer; In the case where the number of photons is greater than the first set threshold, send a first voltage signal with a second voltage value to the isolation part; Wherein, both the first voltage value and the second voltage value are negative values, and the absolute value of the first voltage value is greater than the absolute value of the second voltage value.

16. The control method according to claim 15, wherein When the number of photons is greater than the first set threshold, sending a first voltage signal with a second voltage value to the isolation part, includes: When the number of photons is greater than the first set threshold and less than or equal to the second set threshold, sending a cathode voltage signal with a third voltage value to a second electrode in the pixel wafer; When the number of photons is greater than the second set threshold, sending a cathode voltage signal with a fourth voltage value to the second electrode; Wherein, the second set threshold is greater than the first set threshold, both the third voltage value and the fourth voltage value are positive values, and the third voltage value is greater than the fourth voltage value.

17. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer program instructions, and when the computer program instructions are run by a processor, one or more steps in the control method described in claim 15 or 16 are executed.

Images