Single photon avalanche diode, preparation method thereof and detector

Abstract

The invention provides a single-photon avalanche diode and a preparation method thereof, and a detector, the single-photon avalanche diode comprises a first type epitaxial layer, a second type deep well layer and a first type central well layer, and the second type deep well layer is arranged at one side of the first type epitaxial layer; the first-type central well layer is arranged on one side, deviating from the first-type epitaxial layer, of the second-type deep well layer; the doping concentration of the first-type epitaxial layer is the same as the doping concentration of the first-type central well layer, and in the single-photon avalanche diode provided by the invention, the doping concentration of the first-type epitaxial layer is the same as the doping concentration of the first-type central well layer. According to the single-photon avalanche diode, the first avalanche region with the shallower depth and the second avalanche region with the deeper depth have the same avalanche probability, when one of the first avalanche region and the second avalanche region generates avalanche, a signal can be detected, the light absorption region and the light detection depth are increased, and the light detection efficiency of the single-photon avalanche diode is improved.

Description

Technical Field

[0001] The present application relates to the technical field of photoelectric detection devices, and in particular to a single-photon avalanche diode and a preparation method thereof, and a detector. Background Art

[0002] Single Photon Avalanche Diode (SPAD) is an avalanche photodiode that works in Geiger mode (operating voltage is greater than breakdown voltage). It is widely used in laser radar, medicine, molecular imaging and quantum science due to its advantages of high time resolution, high detection sensitivity and low cost. The working principle of SPAD is: in Geiger mode, when SPAD absorbs photons, electron-hole pairs are generated in the avalanche region, and avalanche multiplication effect occurs under the action of strong electric field, forming avalanche current.

[0003] Photon detection efficiency (PDE) refers to the ratio of the number of detected photons to the number of incident photons. It is used to measure the ability of a single-photon avalanche diode to detect light power and is an important characteristic of a single-photon avalanche diode. By improving the photon detection efficiency of a single-photon avalanche diode, the performance of the single-photon avalanche diode can be improved.

[0004] The SPAD in the related technology has a technical problem of low photon detection efficiency, which needs to be solved urgently. Summary of the invention

[0005] The present application provides a single-photon avalanche diode and a preparation method and a detector, which can effectively solve the technical problem of low photon detection efficiency of single-photon avalanche diodes.

[0006] On the one hand, the present application provides a single-photon avalanche diode, which includes: a first type epitaxial layer; a second type deep well layer, arranged on one side of the first type epitaxial layer; a first type central well layer, arranged on the side of the second type deep well layer away from the first type epitaxial layer; wherein the doping concentration of the first type epitaxial layer is the same as the doping concentration of the first type central well layer; wherein the first type is one of an electronic type and a hole type; and the second type is the other of an electronic type and a hole type.

[0007] Optionally, the potential of the first type epitaxial layer is the same as the potential of the first type central well layer.

[0008] Optionally, the single-photon avalanche diode further includes: a second type substrate, disposed on a side of the first type epitaxial layer away from the second type deep well layer.

[0009] Optionally, the single-photon avalanche diode also includes a second type shallow well layer, which is arranged on the side of the second type deep well layer away from the second type substrate and surrounds the first type central well layer, and the depth of the second type shallow well layer is greater than or equal to the depth of the first type central well layer.

[0010] Optionally, the single-photon avalanche diode also includes a first type edge well layer, which is arranged on the side of the first type epitaxial layer away from the second type substrate and surrounds the second type shallow well layer, and the depth of the first type edge well layer is greater than the depth of the second type shallow well layer.

[0011] Optionally, the single-photon avalanche diode also includes a conduction groove, which is arranged on the side of the second type substrate facing the first type epitaxial layer and surrounds the first type edge well layer, and the depth of the conduction groove is greater than the depth of the first type epitaxial layer.

[0012] Optionally, the first type central well layer is in contact with the second type deep well layer, and a first electrode is provided on the surface of the first type central well layer facing away from the second type substrate; the second type shallow well layer is in contact with the second type deep well layer, and a second electrode is provided on the surface of the second type shallow well layer facing away from the second type substrate.

[0013] Optionally, the first type edge well layer is in contact with the first type epitaxial layer, and a third electrode is disposed on a surface of the first type edge well layer on a side facing away from the second type substrate.

[0014] Optionally, the conductive groove is in contact with the second-type substrate, and a fourth electrode is disposed on a surface of the conductive groove that is away from the second-type substrate.

[0015] Optionally, projections of the edge of the second-type shallow well layer, the edge of the first-type edge well layer and the edge of the conductive trench on the second-type substrate are circular or rectangular with chamfered structures.

[0016] Optionally, the doping concentration of the first type central well layer is 1×10 16 / cm 3 ~1×10 18 / cm 3 .

[0017] Optionally, the doping concentration of the second type deep well layer is 1×10 16 / cm 3 ~1×10 18 / cm 3 .

[0018] In a second aspect, the present application provides a method for preparing a single-photon avalanche diode, which comprises the following steps: forming a first type epitaxial layer on a second type substrate; etching the surface of the first type epitaxial layer away from the second type substrate to form a shallow groove, and filling the shallow groove with an insulating medium to form a shallow groove isolation portion; forming a second type deep well layer, a first type central well layer, a second type shallow well layer and a first type edge well layer on the surface of the first type epitaxial layer away from the second type substrate; forming a deep groove on the surface of the first type epitaxial layer away from the second type substrate, and filling the deep groove with a conductive material to form a conductive groove.

[0019] In a third aspect, the present application also provides a method for preparing a single-photon avalanche diode, which comprises the following steps: forming a first type epitaxial layer on a first type substrate; forming a shallow groove on a surface of the first type epitaxial layer away from the second type substrate, and filling the shallow groove with an insulating medium to form a shallow groove isolation portion; forming a second type deep well layer, a first type central well layer, a second type shallow well layer and a first type edge well layer on a surface of the first type epitaxial layer away from the second type substrate; forming a deep groove on a surface of the first type epitaxial layer away from the second type substrate, and filling the deep groove with a conductive material to form a conductive groove; thinning the first type substrate, and converting the thinned first type substrate into a second type substrate.

[0020] In a fourth aspect, the present application provides a detector, comprising the single photon avalanche diode described in any one of the above items.

[0021] The present application provides a single-photon avalanche diode and a preparation method and a detector thereof. The single-photon avalanche diode includes a first-type epitaxial layer, a second-type deep well layer and a first-type central well layer. The second-type deep well layer is arranged on one side of the first-type epitaxial layer; the first-type central well layer is arranged on the side of the second-type deep well layer away from the first-type epitaxial layer; wherein the doping concentration of the first-type epitaxial layer is the same as the doping concentration of the first-type central well layer; wherein the first type is one of the electronic type and the hole type; the second type is the other of the electronic type and the hole type. In the single-photon avalanche diode provided by the present application, the doping concentration of the first-type epitaxial layer is the same as the doping concentration of the first-type central well layer, so that the first avalanche zone with a shallower depth and the second avalanche zone with a deeper depth have the same avalanche probability. When an avalanche occurs in one of the first avalanche zone and the second avalanche zone, a signal can be detected, thereby increasing the area of ​​light absorption and the light detection depth, and improving the light detection efficiency of the single-photon avalanche diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A schematic cross-sectional view of a single-photon avalanche diode provided for some embodiments of the present application.

[0024] Figure 2 A schematic cross-sectional view of a single-photon avalanche diode provided for some embodiments of the present application.

[0025] Figure 3 A cross-sectional schematic diagram of another single-photon avalanche diode provided for some embodiments of the present application.

[0026] Figure 4 A cross-sectional schematic diagram of another single-photon avalanche diode provided for some embodiments of the present application.

[0027] Figure 5 A schematic flow chart of a method for preparing a single-photon avalanche diode provided in some embodiments of the present application.

[0028] Figure 6 A schematic flow chart of another method for preparing a single-photon avalanche diode provided for some embodiments of the present application.

[0029] Description of reference numerals:

[0030] Single-photon avalanche diode 100; second type substrate 10; first type epitaxial layer 11; second type deep well layer 12; first type central well layer 13; guard ring 14; second type shallow well layer 15; shallow trench isolation 16; first type edge well layer 17; conductive groove 18; first electrode 101; second electrode 102; third electrode 103; fourth electrode 104; single-photon avalanche diode 100`; second type substrate 10`; first type epitaxial layer 11`; second type deep well layer 12`; first type central well layer 13`; guard ring 14`; second type shallow well layer 15`; shallow trench isolation 16`; first type edge well layer 17`; conductive groove 18`; first electrode 101`; second electrode 102`; third electrode 103`; fourth electrode 104`; DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, unless otherwise stated, the directional words such as "upper" and "lower" used generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0032] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the present application provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials. The following is described in detail respectively, and it should be noted that the description order of the following embodiments is not used as a limitation to the preferred order of the embodiments.

[0033] Figure 1 A schematic cross-sectional view of a single-photon avalanche diode provided in some embodiments of the present application; Figure 2 A cross-sectional schematic diagram of a single photon avalanche diode provided in some embodiments of the present application. Figure 1 and Figure 2 As shown, in the first aspect, some embodiments of the present application provide a single-photon avalanche diode 100, wherein the single-photon avalanche diode 100 includes a first-type epitaxial layer 11, a second-type deep well layer 12 and a first-type central well layer 13, wherein the second-type deep well layer 12 is arranged on one side of the first-type epitaxial layer 11; the first-type central well layer 13 is arranged on the side of the second-type deep well layer 12 away from the first-type epitaxial layer 11; wherein the doping concentration of the first-type epitaxial layer 11 is the same as the doping concentration of the first-type central well layer 13; wherein the first type is one of an electronic type and a hole type; and the second type is the other of an electronic type and a hole type.

[0034] In the single-photon avalanche diode 100 provided in some embodiments of the present application, a first-type epitaxial layer 11 and a first-type central well layer 13 are respectively arranged on both sides of the second-type deep well layer 12. Since the doping type of the first-type central well layer 13 is one of the electron type and the hole type, and the doping type of the second-type deep well layer 12 is the other of the electron type and the hole type, the doping types of the two are different, so that the single-photon avalanche diode 100 can form a first avalanche zone at the junction of the first-type central well layer 13 and the second-type deep well layer 12 under the action of an electric field; since the doping type of the first-type epitaxial layer 11 is one of the electron type and the hole type, and the doping type of the second-type deep well layer 12 is the other of the electron type and the hole type, and the doping types of the two are different, so that the single-photon avalanche diode 100 can form a second avalanche zone at the junction of the first-type epitaxial layer 11 and the second-type deep well layer 12 under the action of an electric field.

[0035] The first avalanche zone and the second avalanche zone are regions where electron-hole pairs are generated and avalanche occurs after light absorption. Since the second avalanche zone is arranged on the side of the first avalanche zone away from the first type central well layer 13 and has a deeper depth, it can effectively improve the light detection depth of the single-photon avalanche diode 100, thereby improving the light detection efficiency of the single-photon avalanche diode 100.

[0036] Furthermore, since the doping concentration of the first type epitaxial layer 11 is the same as the doping concentration of the first type central well layer 13, the first avalanche zone with a shallower depth and the second avalanche zone with a deeper depth can have the same avalanche probability. When an avalanche occurs in one of the first avalanche zone and the second avalanche zone, a signal can be detected, thereby increasing the light absorption area and the light detection depth, and improving the light detection efficiency of the single-photon avalanche diode 100.

[0037] In some embodiments of the present application, the first type is a hole type, ie, a P type; and the second type is an electron type, ie, an N type.

[0038] In some embodiments of the present application, the first type is an electron type, ie, an N type, and the second type is a hole type, ie, a P type.

[0039] In some embodiments of the present application, the potential of the first type epitaxial layer 11 is the same as the potential of the first type central well layer 13 .

[0040] In the single-photon avalanche diode 100 provided in some embodiments of the present application, by making the potential of the first-type epitaxial layer 11 and the potential of the first-type central well layer 13 the same, the first PN junction composed of the first-type central well layer 13 and the second-type deep well layer 12 and the second PN junction composed of the first-type epitaxial layer 11 and the second-type deep well layer 12 can have the same electric field distribution, so that the first PN junction and the second PN junction can be in Geiger mode at the same time, and the first avalanche zone and the second avalanche zone have the same avalanche probability, so that the first avalanche zone and the second avalanche zone can work simultaneously and perform the function of optical signal detection at the same time.

[0041] In some embodiments of the present application, the excitation light of the single-photon avalanche diode 100 is infrared light, and the infrared light may be infrared light with a wavelength of 940 nm, or infrared light with a wavelength greater than 1000 nm.

[0042] In the single-photon avalanche diode 100 provided in some embodiments of the present application, since the infrared light signal is absorbed very deeply in silicon, the deep absorption depth of infrared light can be utilized so that the light signal can effectively trigger avalanche in the deeper second avalanche zone.

[0043] In some embodiments of the present application, a distance between a surface of the first type epitaxial layer 11 facing away from the first type central well layer 13 and a surface of the first type central well layer 13 facing away from the first type epitaxial layer 11 is greater than 3 microns.

[0044] In the single-photon avalanche diode 100 provided in some embodiments of the present application, the absorption depth of infrared light in silicon is greater than 3 microns, and the surface of the first-type epitaxial layer 11 on the side away from the first-type central well layer 13 is the area with the deepest effective detection depth of the excitation light. The present application enables the single-photon avalanche diode 100 to fully utilize the characteristic of the deep absorption depth of infrared light by making the distance between the surface of the first-type epitaxial layer 11 on the side away from the first-type central well layer 13 and the surface of the first-type central well layer 13 on the side away from the first-type epitaxial layer 11 greater than 3 microns.

[0045] In some embodiments of the present application, the single photon avalanche diode 100 further includes: a second type substrate 10 disposed on a side of the first type epitaxial layer 11 away from the second type deep well layer 12 .

[0046] In the single-photon avalanche diode 100 provided in some embodiments of the present application, since the doping type of the first-type epitaxial layer 11 is one of the electron type and the hole type, and the doping type of the second-type substrate 10 is the other of the electron type and the hole type, the doping types of the two are different, so that the single-photon avalanche diode 100 can form a protective junction at the junction of the first-type epitaxial layer 11 and the second-type substrate 10.

[0047] In some embodiments of the present application, the potential of the first type epitaxial layer 11 is the same as the potential of the second type substrate 10, or the potential of the first type epitaxial layer 11 is greater than the potential of the second type substrate 10, so that the protective junction formed at the junction of the first type epitaxial layer 11 and the second type substrate 10 can effectively block carriers from diffusing to the second type substrate 10.

[0048] In some embodiments of the present application, the single-photon avalanche diode 100 also includes a second type shallow well layer 15, which is arranged on the side of the second type deep well layer 12 away from the second type substrate 10 and surrounds the first type central well layer 13, and the depth of the second type shallow well layer 15 is greater than or equal to the depth of the first type central well layer 13.

[0049] In the single-photon avalanche diode 100 provided in some embodiments of the present application, the area where the first-type central well layer 13 is located is the main body area of ​​the single-photon avalanche diode 100, and the second-type shallow well layer 15 is arranged around the first-type central well layer 13, and is used to contact and electrically connect with the second-type deep well layer 12. The present application can make the contact effect between the second-type shallow well layer 15 and the second-type deep well layer 12 at their junction better by making the depth of the second-type shallow well layer 15 greater than or equal to the depth of the first-type central well layer 13, which is beneficial to improving the electrical connection stability of the single-photon avalanche diode 100.

[0050] In some embodiments of the present application, the single-photon avalanche diode 100 also includes a first type edge well layer 17, which is arranged on the side of the first type epitaxial layer 11 away from the second type substrate 10 and surrounds the second type shallow well layer 15, and the depth of the first type edge well layer 17 is greater than the depth of the second type shallow well layer 15.

[0051] In the single-photon avalanche diode 100 provided in some embodiments of the present application, the first-type edge well layer 17 is arranged around the second-type shallow well layer 15, and is used to contact and electrically connect with the first-type epitaxial layer 11. By making the depth of the first-type edge well layer 17 greater than the depth of the second-type shallow well layer 15, the present application can make the contact effect between the first-type edge well layer 17 and the first-type epitaxial layer 11 at their junction better, which is beneficial to improving the electrical connection stability of the single-photon avalanche diode 100.

[0052] In some embodiments of the present application, the single-photon avalanche diode 100 also includes a conducting groove 18, which is arranged on the side of the second type substrate 10 facing the first type epitaxial layer 11 and surrounds the first type edge well layer 17, and the depth of the conducting groove 18 is greater than the depth of the first type epitaxial layer 11.

[0053] In the single-photon avalanche diode 100 provided in some embodiments of the present application, the conductive groove 18 is arranged around the first type edge well layer 17, and is used to contact and electrically connect with the second type substrate 10. The present application makes the depth of the conductive groove 18 greater than the depth of the first type epitaxial layer 11, so that the contact effect between the conductive groove 18 and the second type substrate 10 at their junction is better, which is beneficial to improving the electrical connection stability of the single-photon avalanche diode 100.

[0054] In some embodiments of the present application, the photon blocking avalanche diode further includes a guard ring 14 and a shallow trench isolation portion 16. The guard ring 14 is disposed between the first type central well layer 13 and the second type shallow well layer 15, and is used to isolate the first type central well layer 13 from the second type shallow well layer 15; the shallow trench isolation portion 16 is disposed between the second type shallow well layer 15 and the first type edge well layer 17, and is used to isolate the second type shallow well layer 15 from the first type edge well layer 17.

[0055] In some embodiments of the present application, the first type central well layer 13 is in contact with the second type deep well layer 12, and a first electrode 101 is provided on the surface of the first type central well layer 13 facing away from the second type substrate 10, wherein the potential connected to the first electrode 101 can be 0V.

[0056] In some embodiments of the present application, the second type shallow well layer 15 is in contact with the second type deep well layer 12, and a second electrode 102 is provided on the surface of the second type shallow well layer 15 facing away from the second type substrate 10, wherein the potential connected to the second electrode 102 can be a positive voltage, wherein the positive voltage is greater than the breakdown voltage of the first PN junction and the breakdown voltage of the second PN junction.

[0057] In some embodiments of the present application, the first type edge well layer 17 is in contact with the first type epitaxial layer 11, and a third electrode 103 is provided on the surface of the first type edge well layer 17 facing away from the second type substrate 10, wherein the potential connected to the third electrode 103 is the same as the potential connected to the first electrode 101, for example, when the potential connected to the first electrode 101 is 0V, the potential connected to the third electrode 103 is also 0V.

[0058] In some embodiments of the present application, the conductive groove 18 is in contact with the second type substrate 10, and a fourth electrode 104 is provided on the surface of the conductive groove 18 on the side away from the second type substrate 10, wherein the potential connected to the fourth electrode 104 is the same as the potential connected to the third electrode 103, for example, when the potential connected to the third electrode 103 is 0 V, the potential connected to the fourth electrode 104 is also 0 V. In the embodiments of the present application, by making the potential connected to the fourth electrode 104 the same as the potential connected to the third electrode 103, the potential of the first type epitaxial layer 11 and the potential of the second type substrate 10 can be made the same, so that the protective junction formed at the junction of the first type epitaxial layer 11 and the second type substrate 10 can effectively block the diffusion of carriers to the second type substrate 10.

[0059] In some embodiments of the present application, the potential connected to the fourth electrode 104 is lower than the potential connected to the third electrode 103. For example, when the potential connected to the third electrode 103 is 0 V, the potential connected to the fourth electrode 104 is a negative voltage lower than 0 V. In the embodiments of the present application, by making the potential connected to the fourth electrode 104 lower than the potential connected to the third electrode 103, the potential of the first type epitaxial layer 11 can be made greater than the potential of the second type substrate 10, so that the protection junction formed at the junction of the first type epitaxial layer 11 and the second type substrate 10 can effectively block the diffusion of carriers to the second type substrate 10.

[0060] In some embodiments of the present application, projections of the edge of the second type shallow well layer 15 , the edge of the first type edge well layer 17 , and the edge of the conductive trench 18 on the second type substrate 10 are circular.

[0061] In the single-photon avalanche diode 100 provided in some embodiments of the present application, since the projections of the edges of the second-type shallow well layer 15, the first-type edge well layer 17 and the conductive groove 18 on the second-type substrate 10 are circular, it is possible to prevent the edges of the second-type shallow well layer 15, the first-type edge well layer 17 and the conductive groove 18 from generating sharp corners, thereby avoiding the problem of increased dark count rate (full name in English: Dark Count Rate, abbreviated as: DCR) and increased noise of the single-photon avalanche diode 100 caused by the sharp corners.

[0062] In some embodiments of the present application, the doping concentration of the first type central well layer 13 is 1×10 16 / cm 3 ~1×10 18 / cm 3 , and the doping depth of the first type central well layer 13 is less than or equal to 1 micron.

[0063] In some embodiments of the present application, the doping concentration of the second type deep well layer 12 is 1×10 16 / cm 3 ~1×10 18 / cm 3 , and the doping depth of the second type deep well layer 12 is less than or equal to 3 microns, and greater than the doping depth of the first type central well layer 13.

[0064] In some embodiments of the present application, the doping concentration of the first type epitaxial layer 11 is 1×10 16 / cm 3 ~1×10 18 / cm 3 , and the doping depth of the first type epitaxial layer 11 is less than or equal to 4 microns, and greater than the doping depth of the second type deep well layer 12.

[0065] In some embodiments of the present application, the doping concentration of the second type shallow well layer 15 is 1×10 16 / cm 3 ~1×10 18 / cm 3 , and the doping depth of the second type shallow well layer 15 is greater than or equal to the doping depth of the first type central well layer 13 .

[0066] In some embodiments of the present application, the doping concentration of the first type edge well layer 17 is 1×10 16 / cm 3 ~1×10 18 / cm 3, and the doping concentration of the first type edge well layer 17 is less than the doping concentration of the first type central well layer 13 , and the doping depth of the second type shallow well layer 15 is greater than the depth of the second type shallow well layer 15 .

[0067] In some embodiments of the present application, the doping concentration of the guard ring 14 is 1×10 15 / cm 3 That is, the doping concentration of the guard ring 14 is smaller than the doping concentration of the first type central well layer 13 and the doping concentration of the second type shallow well layer 15 , so as to improve the isolation effect of the guard ring 14 .

[0068] Figure 3 A cross-sectional schematic diagram of another single-photon avalanche diode provided for some embodiments of the present application; Figure 4 A schematic plan view of another single photon avalanche diode provided for some embodiments of the present application. Figure 3 and Figure 4 As shown, the single-photon avalanche diode 100' includes a first-type epitaxial layer 11', a second-type deep well layer 12' and a first-type central well layer 13', wherein the second-type deep well layer 12' is arranged on one side of the first-type epitaxial layer 11'; the first-type central well layer 13' is arranged on the side of the second-type deep well layer 12' away from the first-type epitaxial layer 11'; wherein the doping concentration of the first-type epitaxial layer 11' is the same as the doping concentration of the first-type central well layer 13'; wherein the first type is one of the electronic type and the hole type; and the second type is the other of the electronic type and the hole type. The single-photon avalanche diode 100' also includes a second-type substrate 10', a second-type shallow well layer 15', a first-type edge well layer 17', a conductive trench 18', a guard ring 14' and a shallow trench isolation 16', a first electrode 101', a second electrode 102', a third electrode 103' and a fourth electrode 104'.

[0069] It should be noted that Figure 3-4 The structure of the single photon avalanche diode 100 is similar to Figure 1-2 The structure of the single photon avalanche diode 100 ′ shown is similar, and the same parts are not described again.

[0070] The difference is that the projections of the edge of the second type shallow well layer 15 ′, the edge of the first type edge well layer 17 ′ and the edge of the conductive groove 18 ′ on the second type substrate 10 ′ are rectangles including chamfered structures.

[0071] In the single-photon avalanche diode 100' provided in some embodiments of the present application, since the projection of the edges of the second-type shallow well layer 15', the first-type edge well layer 17' and the conductive groove 18' on the second-type substrate 10' is a rectangle including a chamfered structure, it is possible to prevent the edges of the second-type shallow well layer 15', the first-type edge well layer 17' and the conductive groove 18' from generating sharp corners, thereby avoiding the problems of increased dark count rate and noise of the single-photon avalanche diode 100' caused by the sharp corners.

[0072] Figure 5 A schematic diagram of a process for preparing a single photon avalanche diode provided in some embodiments of the present application. Figure 1-Figure 5 As shown, in the second aspect, some embodiments of the present application also provide a method for preparing a single-photon avalanche diode, which is used to prepare the single-photon avalanche diode described in any of the above embodiments. Wherein, the single-photon avalanche diode includes step S01, step S02, step S03, and step S04.

[0073] Wherein, step S01 includes: forming a first type epitaxial layer on a second type substrate.

[0074] Wherein, step S02 includes: etching the surface of the first type epitaxial layer away from the second type substrate to form a shallow groove, and filling the shallow groove with an insulating medium to form a shallow groove isolation portion.

[0075] Wherein, step S03 includes: forming a second type deep well layer, a first type central well layer, a second type shallow well layer and a first type edge well layer on a surface of the first type epitaxial layer away from the second type substrate.

[0076] Wherein, step S04 includes: forming a deep groove on the surface of the first type epitaxial layer away from the second type substrate, and filling the deep groove with a conductive material to form a conductive trench, and the conductive material may be tungsten.

[0077] Figure 6 A schematic diagram of another method for preparing a single photon avalanche diode provided in some embodiments of the present application. Figure 1-Figure 4 and Figure 6 As shown, in the third aspect, some embodiments of the present application also provide another method for preparing a single-photon avalanche diode, which is used to prepare the single-photon avalanche diode described in any of the above embodiments. Wherein, the single-photon avalanche diode includes step M01, step M02, step M03, step M04, and step M05.

[0078] Wherein, step M01 includes: forming a first type epitaxial layer on a first type substrate.

[0079] Wherein, step M02 includes: forming a shallow trench on a surface of the first type epitaxial layer away from the second type substrate, and filling the shallow trench with an insulating medium to form a shallow trench isolation portion.

[0080] Wherein, step M03 includes: forming a second type deep well layer, a first type central well layer, a second type shallow well layer and a first type edge well layer on a surface of the first type epitaxial layer away from the second type substrate.

[0081] Wherein, step M04 includes: forming a deep groove on the surface of the first type epitaxial layer away from the second type substrate, and filling the deep groove with a conductive material to form a conductive trench, and the conductive material may be tungsten.

[0082] Wherein, step M05 includes: thinning the first type substrate and converting the thinned first type substrate into a second type substrate. Wherein, since the implantation depth of the implantation process is limited, usually at the micron level, the first type substrate needs to be thinned first to ensure that the implantation depth can reach the junction of the first type substrate and the first type epitaxial layer.

[0083] In a fourth aspect, some embodiments of the present application further provide a detector, comprising the single photon avalanche diode described in any one of the above embodiments.

[0084] In summary, the present application provides a single-photon avalanche diode and a preparation method and a detector thereof. The single-photon avalanche diode includes a first-type epitaxial layer, a second-type deep well layer and a first-type central well layer. The second-type deep well layer is arranged on one side of the first-type epitaxial layer; the first-type central well layer is arranged on the side of the second-type deep well layer away from the first-type epitaxial layer; wherein the doping concentration of the first-type epitaxial layer is the same as the doping concentration of the first-type central well layer; wherein the first type is one of the electronic type and the hole type; the second type is the other of the electronic type and the hole type. In the single-photon avalanche diode provided by the present application, the doping concentration of the first-type epitaxial layer is the same as the doping concentration of the first-type central well layer, so that the first avalanche zone with a shallower depth and the second avalanche zone with a deeper depth have the same avalanche probability. When an avalanche occurs in one of the first avalanche zone and the second avalanche zone, a signal can be detected, thereby increasing the area of ​​light absorption and the light detection depth, and improving the light detection efficiency of the single-photon avalanche diode.

[0085] The single-photon avalanche diode and its preparation method and detector provided in the embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technical personnel in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A single photon avalanche diode, characterized in that: The single photon avalanche diode comprises: A first type epitaxial layer; A second type deep well layer is disposed on one side of the first type epitaxial layer; A first type central well layer is arranged on a side of the second type deep well layer away from the first type epitaxial layer; Wherein, the doping concentration of the first type epitaxial layer is the same as the doping concentration of the first type central well layer; The first type is one of the electron type and the hole type; the second type is the other of the electron type and the hole type.

2. The single photon avalanche diode according to claim 1, characterized in that: The potential of the first type epitaxial layer is the same as the potential of the first type central well layer.

3. The single photon avalanche diode according to claim 1, characterized in that: The single photon avalanche diode further includes: a second type substrate, which is arranged on a side of the first type epitaxial layer away from the second type deep well layer.

4. The single photon avalanche diode according to claim 3, characterized in that: The single-photon avalanche diode also includes a second type shallow well layer, which is arranged on the side of the second type deep well layer away from the second type substrate and surrounds the first type central well layer, and the depth of the second type shallow well layer is greater than or equal to the depth of the first type central well layer.

5. The single photon avalanche diode according to claim 4, characterized in that: The single-photon avalanche diode also includes a first type edge well layer, which is arranged on the side of the first type epitaxial layer away from the second type substrate and surrounds the second type shallow well layer, and the depth of the first type edge well layer is greater than the depth of the second type shallow well layer.

6. The single photon avalanche diode according to claim 5, characterized in that: The single photon avalanche diode also includes a conducting trench, which is arranged on the side of the second type substrate facing the first type epitaxial layer and surrounds the first type edge well layer, and the depth of the conducting trench is greater than the depth of the first type epitaxial layer.

7. The single photon avalanche diode according to claim 4, characterized in that: The first type central well layer is in contact with the second type deep well layer, and a first electrode is disposed on a surface of the first type central well layer on a side away from the second type substrate; The second-type shallow well layer is in contact with the second-type deep well layer, and a second electrode is disposed on a surface of the second-type shallow well layer at a side away from the second-type substrate.

8. The single photon avalanche diode according to claim 5, characterized in that: The first type edge well layer is in contact with the first type epitaxial layer, and a third electrode is disposed on a surface of the first type edge well layer at a side facing away from the second type substrate.

9. The single photon avalanche diode according to claim 6, characterized in that: The conductive groove is in contact with the second-type substrate, and a fourth electrode is disposed on a surface of the conductive groove facing away from the second-type substrate.

10. The single photon avalanche diode according to claim 6, characterized in that: Projections of the edge of the second-type shallow well layer, the edge of the first-type edge well layer and the edge of the conductive trench on the second-type substrate are circular or rectangular with chamfered structures.

11. The single photon avalanche diode according to claim 1, characterized in that: The doping concentration of the first type central well layer is 1×10 16 / cm 3 ~1×10 18 / cm 3 .

12. The single photon avalanche diode according to claim 11, characterized in that: The doping concentration of the second type deep well layer is 1×10 16 / cm 3 ~1×10 18 / cm 3 .

13. A method for preparing a single photon avalanche diode, characterized in that: The preparation method of the single photon avalanche diode comprises the following steps: forming a first type epitaxial layer on a second type substrate; Etching a surface of the first type epitaxial layer facing away from the second type substrate to form a shallow groove, and filling the shallow groove with an insulating medium to form a shallow groove isolation portion; forming a second type deep well layer, a first type central well layer, a second type shallow well layer and a first type edge well layer on a surface of the first type epitaxial layer away from the second type substrate; A deep trench is formed on a surface of the first type epitaxial layer facing away from the second type substrate, and a conductive material is filled in the deep trench to form a conductive trench.

14. A method for preparing a single photon avalanche diode, characterized in that: The preparation method of the single photon avalanche diode comprises the following steps: forming a first type epitaxial layer on a first type substrate; forming a shallow trench on a surface of the first type epitaxial layer facing away from the second type substrate, and filling the shallow trench with an insulating medium to form a shallow trench isolation portion; forming a second type deep well layer, a first type central well layer, a second type shallow well layer and a first type edge well layer on a surface of the first type epitaxial layer away from the second type substrate; forming a deep groove on a surface of the first type epitaxial layer facing away from the second type substrate, and filling the deep groove with a conductive material to form a conductive trench; The first type substrate is thinned and the thinned first type substrate is converted into a second type substrate.

15. A detector, characterized in that: A single photon avalanche diode comprising any one of claims 1-12.

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