Single-photon detector, method for manufacturing the same, and single-photon detector matrix

Abstract

A single-photon detector and a method for manufacturing the same, and a single-photon detector matrix are provided. [Solution] A multi-layer epitaxial layer including a buffer layer, an absorption layer, a transition layer, a charge layer, a multiplication layer, an inversion layer, a transition layer, a window layer and an ohmic contact layer are sequentially formed on one side of a provided substrate, a curved diffusion area is formed in the ohmic contact layer and the window layer by a diffusion technique, a platform structure is formed by etching the periphery of a part of the epitaxial layer on the substrate, an optical window is formed on the rear surface of the substrate for the incidence of incident light, a P-type electrode is formed on the ohmic contact layer, and an N-type electrode is formed on the rear surface of the substrate. The present invention can effectively reduce the electric field around the periphery of the diffusion area by only a primary diffusion process, effectively suppress the edge destruction problem, and effectively reduce the complexity of the manufacturing technology compared with the traditional method that requires a secondary diffusion process or secondary growth.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices. Specifically, it relates to a single photon detector, a method for manufacturing the same, and a single photon detector matrix.

Background Art

[0002] Light is composed of individual small energy units. That is, a photon is the smallest constituent unit of light. The energy of a single photon is 10 - 19 joules in the visible or near-infrared wavelength range, and it is impossible to achieve effective detection of a single photon with conventional optoelectronic detectors. A single photon detector has advantages such as high sensitivity, a high signal-to-noise ratio, and low timing jitter. For this reason, single photon detectors have emerged in a timely manner. Single photon detection technology is widely applied in weak light detection fields such as quantum key distribution, laser distance measurement, bioluminescence detection, and DNA reactions.

[0003] At present, single-photon detectors mainly include photomultiplier tubes (PMTs), superconducting single-photon detectors, single-photon avalanche diodes (SPADs), etc. Among them, PMTs mainly utilize the electron multiplication mechanism and have advantages such as high gain and high sensitivity. Their gain can reach 10^4 to 10^8. However, the disadvantages are that the response to spectra above 1200 nm is very poor, the size is large, and the dark count is relatively large, so it cannot meet the current demand for single-photon detection. Superconducting single-photon detectors mainly utilize the superconducting phase change mechanism, have the characteristics of high sensitivity and low noise, and have a relatively high detection rate. However, due to the operating environment being in a cryogenic environment, their applications in daily production and life are greatly limited. SPADs are mainly based on the impact ionization mechanism and utilize the avalanche effect to form a relatively large macroscopically observable current. Considering practicality, SPADs can operate in the visible or near-infrared wavelength range, have advantages such as high gain, high signal-to-noise ratio, low power consumption, and small volume, and are currently the single-photon detectors with the widest applications and the greatest application potential. To obtain a relatively large gain, SPADs usually operate in the Geiger mode, that is, the operating voltage is greater than the breakdown voltage, and problems such as edge breakdown exist.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The object of the present invention includes, for example, providing a single-photon detector and its manufacturing method, a single-photon detector matrix, effectively suppressing the problem of edge breakdown, and reducing the complexity of the manufacturing technology.

Means for Solving the Problems

[0005] Embodiments of the present invention can be realized as follows: In a first aspect, the present invention provides a method for manufacturing a single-photon detector. The method includes sequentially forming a multilayer epitaxial layer including a buffer layer, an absorption layer, a transition layer, a charge layer, a multiplication layer, an inversion layer, a transition layer, a window layer, and an ohmic contact layer on one side of a provided substrate; forming a curved diffusion area in the ohmic contact layer and the window layer by a diffusion technique; forming a platform structure by etching the periphery of a part of the epitaxial layer on the substrate; forming a light window for incident light to enter on the back surface of the substrate; forming a P-type electrode on the ohmic contact layer, and forming an N-type electrode on the back surface of the substrate. Among them, the inversion layer is used to perform secondary adjustment control on the electric field distribution based on the adjustment control of the charge layer.

[0006] In an alternative embodiment, the inversion layer is composed of one or a combination of InP, InGaAs, InAlAs, InAlGaAs, and InGaAsP.

[0007] In an alternative embodiment, the integrated charge density of the inversion layer is in the range of 2.0*e 12 / cm 2 ~4.0*e 12 / cm 2 within the range.

[0008] In an alternative embodiment, the thickness of the charge layer is in the range of 150 nm to 300 nm, the thickness of the multiplication layer is in the range of 400 nm to 800 nm, and the thickness of the inversion layer is in the range of 150 nm to 300 nm.

[0009] In an alternative embodiment, the step of forming a curved diffusion area between the ohmic contact layer and the window layer by the diffusion technique includes forming an etching layer on the ohmic contact layer, defining an etching area in the etching layer, and etching the etching layer based on the etching area to form an etching opening to expose a part of the ohmic contact layer. By performing P-type diffusion on the ohmic contact layer and the window layer by adopting the diffusion technique through the etching opening, a curved diffusion area of P-type doping is formed.

[0010] In an alternative embodiment, the step of forming a platform structure by etching at least a part of the periphery of the epitaxial layer on the substrate includes etching the periphery of the ohmic contact layer, the window layer, the transition layer, the inversion layer, the multiplication layer, the charge layer, the transition layer, the absorption layer, the buffer layer, and a part of the substrate to form a first platform in the upper area of the substrate, and etching the periphery of the ohmic contact layer, the window layer, the transition layer, and the inversion layer to form a second platform in the upper area of the multiplication layer.

[0011] In an alternative embodiment, after the step of forming the second platform in the upper area of the multiplication layer by etching the periphery of the ohmic contact layer, the window layer, the transition layer, and the inversion layer, the method further includes forming a passivation layer on the first platform and the second platform, which is composed of a high-resistance polymer material or one or more of SiO2, SiN x , Al2O3.

[0012] In an alternative embodiment, the step of forming a light window on the back surface of the substrate includes performing an etching process on the back surface of the substrate with an etching thickness smaller than the thickness of the substrate.

[0013] In a second aspect, the present invention provides a single photon detector, including a substrate, a buffer layer, an absorption layer, a transition layer, a charge layer, a multiplication layer, an inversion layer, a transition layer, a window layer, and an ohmic contact layer that are sequentially formed on the substrate. A curved diffusion area is formed in the ohmic contact layer and the window layer, and the periphery of a part of the epitaxial layer of the substrate is etched to form a platform structure. The multi-layer epitaxial layer includes a light window formed on the back surface of the substrate for incident light, a P-type electrode formed on the ohmic contact layer, and an N-type electrode formed on the back surface of the substrate. Among them, the inversion layer is used to perform secondary adjustment control on the electric field distribution based on the adjustment control of the charge layer.

[0014] In an alternative embodiment, the platform structure includes a first platform formed in the upper area of the substrate by etching the ohmic contact layer, the window layer, the transition layer, the inversion layer, the multiplication layer, the charge layer, the transition layer, the absorption layer, the buffer layer, and the periphery of a part of the substrate, and a second platform formed in the upper area of the multiplication layer by etching the periphery of the ohmic contact layer, the window layer, the transition layer, and the inversion layer.

[0015] In an alternative embodiment, the single photon detector further includes a passivation layer grown on the first platform and the second platform. The passivation layer is composed of a high-resistance polymer material, or one or more of SiO2, SiN x , Al2O3.

[0016] In an alternative embodiment, the inversion layer is composed of one or more of InP, InGaAs, InAlAs, InAlGaAs, InGaAsP.

[0017] In an alternative embodiment, the integrated charge density of the inversion layer is 2.0*e 12 / cm 2 ~4.0*e 12 / cm2 is within the range of.

[0018] In an alternative embodiment that can be selected, the thickness of the charge layer is 150 nm to 300 nm, the thickness of the multiplication layer is 400 nm to 800 nm, and the thickness of the inversion layer is 150 nm to 300 nm.

[0019] In a third aspect, the present invention provides a single photon detector matrix, including the single photon detectors of the plurality of embodiments. The plurality of single photon detectors are arranged to form a matrix, and the plurality of single photon detectors are integrated into a readout circuit by flip-chip bonding technology. The P-type electrodes of each single photon detector are spaced apart from each other, and the plurality of single photon detectors share an N-type electrode. Effects of the present invention

[0020] This application provides a single photon detector, a manufacturing method thereof, and a single photon detector matrix. On one side of the provided substrate, a multilayer epitaxial layer including a buffer layer, an absorption layer, a transition layer, a charge layer, a multiplication layer, an inversion layer, a transition layer, a window layer, and an ohmic contact layer is grown in sequence. And by forming a curved diffusion area in the ohmic contact layer and the window layer by diffusion technology, etching is performed on the periphery of a part of the epitaxial layer of the substrate to form a platform structure, a light window is formed on the back surface of the substrate, and a P-type electrode is formed on the ohmic contact layer, and an N-type electrode is formed on the back surface of the substrate. The present invention effectively reduces the electric field at the periphery of the diffusion area by combining the inversion layer only through a primary diffusion process, effectively suppresses the edge breakdown problem, and effectively reduces the complexity of the manufacturing technology compared with the conventional method that requires a secondary diffusion process or secondary growth.

Brief Description of the Drawings

[0021] To describe the technology of the embodiments of the present invention in more detail, the following briefly introduces the attached drawings that need to be used for the embodiments. It should be understood that the following attached drawings show only some embodiments of the present invention and should not be regarded as a limitation to the scope. For those of ordinary skill in the art, without creative labor, other related drawings can be obtained based on these attached drawings.

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DETAILED DESCRIPTION OF THE INVENTION

[0022] Single-photon detectors commonly seen in the prior art mainly include two types. One of the main manufacturing techniques involves sequentially forming a buffer layer, an absorption layer, a transition layer, a charge layer, a multiplication layer, and an intrinsic layer on a substrate. Then, a secondary diffusion technique is adopted to form diffusion areas in the intrinsic layer, the multiplication layer, and the charge layer, and the formed structure is shown in FIG. 1. The distribution diagram of the electric field of the structure formed in this way is as shown in FIG. 2. As shown in FIG. 2, due to the action of the charge layer, the electric field is the strongest in the multiplication layer and relatively weak in the absorption layer, ensuring that the multiplication layer generates impact ionization. Instead of ionizing the absorption layer, it can ensure that charge carriers migrate at a saturation speed, improving the response speed of the APD. The single-photon detector formed by this method can effectively suppress the edge breakdown effect. However, since the secondary diffusion technique is used to form the pn junction, there are problems such as difficulty in controlling the technology and low yield. Moreover, it is difficult to create a large-area matrix structure.

[0023] In addition, the second method involves sequentially forming a buffer layer, an absorption layer, a transition layer, a charge layer, a multiplication layer, and an intrinsic layer on a substrate. Then, a diffusion technique is used to form diffusion areas in the intrinsic layer and the multiplication layer, and the charge layer is etched to form a platform. Furthermore, an indium phosphide layer is formed on the etched platform using a secondary epitaxial technique, and the formed structure is as shown in FIG. 3. The single-photon detector formed by this method can effectively suppress the edge breakdown effect. However, this method adopts primary diffusion and also utilizes etching technology and secondary epitaxial technology. Therefore, the interface of the secondary epitaxy is very difficult to control under high electric field conditions, and there are problems such as complex manufacturing technology and low yield rate.

[0024] Based on the above research findings, the present application provides a method for manufacturing a single-photon detector, forming an inversion layer in the charge layer during primary epitaxy, and performing secondary adjustment control on the distribution of the electric field based on the adjustment control in the charge layer of the inversion layer. By combining with the inversion layer only through primary diffusion treatment, the edge electric field of the diffusion area can be effectively suppressed, and the edge breakdown problem can be effectively suppressed. Moreover, compared with the conventional methods that require secondary diffusion treatment or secondary epitaxy, the complexity of the manufacturing technology can be effectively suppressed.

[0025] To make the objectives, technical means, and advantages of the embodiments of the present invention clearer, the following will, in combination with the accompanying drawings in the embodiments of the present invention, provide a clearer and more complete description of the technical means in the embodiments of the present invention. Of course, the described embodiments are only some of the embodiments of the present invention, not all of them. Generally, the components of the embodiments of the present invention described and shown in this accompanying drawing can be arranged and designed in various arrangements.

[0026] Therefore, the following will elaborate on the embodiments of the present invention provided in the accompanying drawings in detail. This is not to limit the scope to be protected by the present invention, but merely to show the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained on the premise that those skilled in the art do not perform creative labor belong to the protection scope of the present invention.

[0027] It should be noted that similar reference numerals and letters indicate similar items in the following accompanying drawings. Therefore, once an item is defined in the accompanying drawings, there is no need for further definition and explanation in subsequent accompanying drawings.

[0028] In the details of the present invention, when terms indicating directions or positional relationships such as "upper", "lower", "inner", "outer", etc. appear, they are based on the directions or positional relationships shown in the accompanying drawings, or the directions or positional relationships customarily placed when using the product of the present invention. This is used for the convenience of explaining the present invention and simplifying the description, and is not for explicitly or implicitly indicating that the device or member to be described has a specific direction or is controlled in a specific direction or structure. Therefore, it should not be understood as a limitation to the present invention.

[0029] In addition, when terms such as "first", "second", etc. appear, they are only used for distinguishing descriptions and should not be understood as indicating relative importance explicitly or implicitly.

[0030] It should be noted that if there is no contradiction, the features in the embodiments of the present invention can be combined with each other.

[0031] Please refer to FIG. 4. The embodiment of the present application provides a method for manufacturing a single-photon detector, and this manufacturing method can be used for manufacturing a single-photon detector. The following will describe this manufacturing method in detail.

[0032] Please refer to FIGS. 5 to 10 together. In step S110, a multilayer epitaxial layer is sequentially grown on one side of the provided substrate 00. The multilayer epitaxial layer includes a buffer layer 10, an absorption layer 20, a transition layer 30, a charge layer 40, a multiplication layer 50, an inversion layer 60, a transition layer 70, a window layer 80, and an ohmic contact layer 90.

[0033] In step S120, a curved diffusion area is formed in the ohmic contact layer 90 and the window layer 80 by diffusion technology.

[0034] In step S130, an etching is performed on the periphery of a part of the epitaxial layer on the substrate 00 to form a platform structure.

[0035] In step S140, an optical window for incident light to enter is formed on the back surface of the substrate 00.

[0036] In step S150, a P-type electrode 93 is formed on the ohmic contact layer 90, and an N-type electrode 94 is formed on the back surface of the substrate 00.

[0037] In this embodiment, the inversion layer 60 introduced during epitaxial growth can perform further secondary adjustment control on the distribution of the electric field based on the adjustment control of the charge layer 40, and the finally obtained device structure is as shown in FIG. 10.

[0038] SPAD (Single Photon Avalanche Photo Diode) operates at a reverse bias voltage, that is, the electrode on the back surface of the SPAD is connected to a high potential, and the upper electrode is connected to a low potential. Incident light enters from the side where the back electrode is located towards the upper electrode, is absorbed in the absorption layer 20 and generates hole pairs. The holes generated by light pass through the multiplication layer 50 and generate more hole pairs due to the avalanche effect. Among them, there is a relatively large energy level difference between the absorption layer 20 and the charge layer 40, and the energy level difference between the multiplication layer 50 and the absorption layer 20 is relatively small. Therefore, the charge carrier stagnation caused by the discontinuity of the band structure between the absorption layer 20 and the charge layer 40 can be alleviated by the multiplication layer 50. In this embodiment, by introducing the inversion layer 60, the electric field of the transition layer 70 is lowered to ensure that the interface between the transition layer 70 and the window layer 80 operates under the action of a relatively low electric field, and the edge breakdown effect can be effectively suppressed. By adjusting the internal electric field of the SPAD through the electric field strengths of the charge layer 40 and the inversion layer 60, appropriate electric field strengths can be given to each layer in the depletion state when the SPAD is in the operating state, realizing the high-speed movement of charge carriers, and preventing the generation of excessive dark current caused by an overly high electric field and the generation of a harmful avalanche multiplication effect.

[0039] For example, referring to FIG. 11, FIG. 11 is an explanatory diagram of the electric field distribution of the single-photon detector provided by the embodiment of the present application. The electric field strength of the multiplication layer 50 is greater than 5×10 5 V / cm, the electric field strength of the absorption layer 20 is less than 1×10 5 V / cm, and it can be seen that the electric field strength of the transition layer 70 is less than 1×10 5 V / cm.

[0040] The manufacturing method of the single-photon detector provided by this embodiment only adopts primary diffusion treatment, and by combining the inversion layer 60, it effectively suppresses the edge breakdown problem, does not require secondary growth, has the advantages of simple technology, high reliability, and high yield. Compared with the method that requires secondary diffusion in the prior art and the method that combines etching and secondary epitaxy in primary diffusion, the complexity of the technology can be reduced. Therefore, this manufacturing method is very suitable for the production of single-photon detector matrices.

[0041] Please refer to FIG. 5. In this embodiment, in step S110, the multi-layer epitaxial layer includes a buffer layer 10, an absorption layer 20, a transition layer 30, a charge layer 40, a multiplication layer 50, an inversion layer 60, a transition layer 70, a window layer 80, and an ohmic contact layer 90, and can be sequentially formed by primary epitaxy.

[0042] Among them, the inversion layer 60 can be composed of a combination of one or more materials among InP, InGaAs, InAlAs, InAlGaAs, and InGaAsP, and the inversion layer 60 can be a P-type doped layer. For example, it can be p-type InAlAs, specifically In 0.52 Al 0.48 As. The integral charge density of the inversion layer 60 is 2.0×e 12 / cm 2 ~4.0×e 12 / cm 2 For example, it can be 3.2×e 12 / cm 2It can be. The thickness of the inversion layer 60 can be 150 nm to 300 nm, and effects such as electric field adjustment control and suppression of edge breakdown can be obtained.

[0043] In this embodiment, the substrate 00 can be a highly doped n-type InP substrate 00, and in the step of forming the buffer layer 10 on the substrate 00, an n-type buffer layer 10 can be formed on the substrate 00 using MOCVD technology. Here, the lattice coefficient of the buffer layer 10 is close to that of the substrate 00. For example, the buffer layer 10 can be an InP layer and can have a thickness between 50 nm and 2000 nm. The range of the doping concentration of the buffer layer 10 is n-type 1*e 15 / cm 3 ~1*e 19 / cm 3 It can be.

[0044] For example, the thickness of the buffer layer 10 can be 1000 nm, and the doping concentration can be 1*e 18 / cm 3 It can be.

[0045] In this embodiment, the absorption layer 20 formed on the buffer layer 10 can be made of an n-type InGaAs material and can have a thickness range of 2000 nm to 2800 nm. For example, the thickness can be 2000 nm and the doping is intrinsic n-type doping. The transition layer 30 can be an intrinsic layer, has a three-stage transition (transient), can be made of an InGaAsP material, and its thickness range can be 10 nm to 300 nm. In this embodiment, the transition layer 30 can effectively improve the response of the device.

[0046] The thickness of the charge layer 40 can be 150 nm to 300 nm, the charge layer 40 can be made of an n-type InP material, and the integrated charge density of the charge layer 40 is 2.4*e 12 / cm 2 ~4.8*e 12 / cm 2 It can be, for example, 2.4*e12 / cm 2 It can be such that an electric field adjustment control and an effect of suppressing edge breakdown can be obtained.

[0047] The multiplication layer 50 is a place in the device where charge carriers generate impact ionization with the lattice. The multiplication layer 50 includes, but is not limited to, hole-type APD impact ionization materials such as InP, AlGaAsSb, and SiC. The characteristic of the hole-type APD impact ionization material is that the hole impact ionization coefficient of the material is higher than the electron ionization coefficient.

[0048] The thickness range of the multiplication layer 50 can be 400 nm to 800 nm. For example, the multiplication layer 50 can be formed of an intrinsic InP material and can have a thickness of 500 nm.

[0049] The transition layer 70 includes, but is not limited to, a combination of one or more materials among InP, InGaAs, InAlAs, InAlGaAs, InGaAsP, etc. The thickness range of the transition layer 70 is 500 nm to 700 nm. For example, it can be 500 nm. The doping is intrinsic n-type or n-type light doping, and the doping range is n-type 1*e 15 / cm 3 ~1*e 17 / cm 3 It can be such that.

[0050] The window layer 80 and the ohmic contact layer 90 can be completed by a primary diffusion technique. The range of the diffusion concentration is 1*e 17 / cm 3 ~5*e 19 / cm 3 is. Among them, the window layer 80 and the ohmic contact layer 90 can also be grown and completed by MOCVD. The range of the doping concentration is 1*e 17 / cm 3 ~5*e 19 / cm 3It is so. The thickness of the window layer 80 is 1000 nm to 1500 nm. The thickness of the ohmic contact layer 90 is 100 nm to 200 nm, and for example, it can be 100 nm. The ohmic contact layer 90 is mainly used for P-type ohmic contact. The higher its doping concentration, the easier it is to achieve ohmic contact. Although the thickness is not an important parameter, if it is too thick, it will affect the diffusion rate of P-type doping.

[0051] Please refer to FIG. 6 together. In this embodiment, in the above step S120, a curved diffusion area can be formed in the ohmic contact layer 90 and the window layer 80 in the following manner. An etching layer is formed on the ohmic contact layer 90, an etching area is defined in the etching layer, and based on the etching area, etching is performed on the etching layer to form an etching opening, and a part of the ohmic contact layer 90 is exposed by the etching opening. By adopting a diffusion technique based on the etching opening to perform P-type diffusion on the ohmic contact layer 90 and the window layer 80, a curved diffusion area of P-type doping is formed.

[0052] In this embodiment, an etching layer can be formed on the ohmic contact layer 90 by a plasma-enhanced chemical vapor deposition (PECVD) method. This etching layer can adopt silicon dioxide (SiO2) or SiN x thin film, and the thickness of the formed etching layer can be 400 nm.

[0053] An etching area is defined in the etching layer. This etching area can be the central position of the etching layer, for example, a circular area at the central position. By adopting a gray-scale exposure technique and an etching technique to perform etching on the etching layer based on the etching area, an etching opening penetrating the etching layer can be formed.

[0054] Based on the etching opening, P-type diffusion is performed on the ohmic contact layer 90 and the underlying window layer 80 to form a curved diffusion area of P-type doping.

[0055] After the diffusion is completed, the remaining etching layer can be peeled off and the device can be cleaned.

[0056] In this embodiment, in step S130, etching is performed on the ohmic contact layer 90, the window layer 80, the transition layer 70, the inversion layer 60, the multiplication layer 50, the charge layer 40, the transition layer 30, the absorption layer 20, the buffer layer 10, and a part of the periphery of the substrate 00, so as to form a first platform in the upper area of the substrate 00. By performing etching on the periphery of the ohmic contact layer 90, the window layer 80, the transition layer 70, and the inversion layer 60, the platform structure can be formed by a method of forming a second platform in the upper area of the multiplication layer 50.

[0057] In this embodiment, etching can be performed on the periphery of the ohmic contact layer 90, the window layer 80, the transition layer 70, the inversion layer 60, the multiplication layer 50, the charge layer 40, the transition layer 30, the absorption layer 20, the buffer layer 10, and a part of the substrate 00 above the substrate 00. By performing the etching process by dry etching, wet etching, or a combination of both, a first platform can be formed on the substrate 00. When performing the etching process by a combination of dry etching and wet etching, the ohmic contact layer 90 can be corroded with a sulfuric acid-based solution. In this embodiment, since the window layer 80 is an InP layer, it is easier to corrode the window layer 80 by adopting a hydrochloric acid-based solution.

[0058] By forming a first platform on the substrate 00, when forming a matrix based on a plurality of single-photon detectors subsequently, the single-photon detectors are likely to be separated from each other. The width of the etching can be between 1 μm and 100 μm, and can be, for example, 5 μm. That is, the distance between the single-photon detectors in the subsequent matrix is between 1 μm and 100 μm.

[0059] On the basis of the above, by further etching the periphery of the ohmic contact layer 90, the window layer 80, the transition layer 70, and the inversion layer 60, a second platform is formed in the upper area of the multiplication layer 50 to form the device structure shown in FIG. 7.

[0060] In this embodiment, etching can be performed on the periphery of the ohmic contact layer 90, the window layer 80, the transition layer 70, and the inversion layer 60 by a dry etching method, a wet etching method, or a combination of both. The etching stops at the surface of the multiplication layer 50, thereby forming a second platform in the upper area of the multiplication layer 50, realizing large-area absorption and small-size multiplication, and achieving the advantageous effects of improving the efficiency of optical detection and reducing dark counts.

[0061] In this embodiment, when adopting a method combining dry etching and wet etching, by corroding the ohmic contact layer 90 with a sulfuric acid-based solution, the problem that the InP window layer 80 is likely to be corroded when adopting a hydrochloric acid-based solution is avoided, ensuring that a platform is formed in the upper area of the multiplication layer 50.

[0062] Please refer to FIG. 8 in combination. On the basis of the above, the manufacturing method provided in this embodiment further includes the step of forming a passivation layer 91 on the first platform and the second platform.

[0063] In this embodiment, the passivation layer 91 can be formed on the first platform and the second platform by adopting the PECVD technology. The passivation layer 91 is composed of a high-resistance polymer material, or can be composed of one or more of SiO2, SiN x , Al2O3. The passivation layer 91 is formed on the side walls and the horizontal planes of the first platform and the second platform.

[0064] The thickness of the passivation layer 91 can be 5 nm to 3000 nm, thereby performing passivation on the platform. For example, using the PECVD technology to create a SiN x thin film, and the thickness of the thin film is 500 nm. In this embodiment, the formed passivation layer 91 can achieve the effect of reducing the dark current by inactivating the platform.

[0065] Please refer to FIG. 9 in combination. In this embodiment, in the above step S140, a corrosion treatment with a thickness smaller than the thickness of the substrate 00 is performed on the back surface of the substrate 00, and a light window can be formed on the back surface of the substrate 00 by growing a multiplication transmission film 92 on the corrosion area of the substrate 00.

[0066] In this embodiment, the multiplication transmission film 92 to be grown can be silicon dioxide (SiO2), SiN x , or other similar optical thin films. For example, it is possible to create a SiN x thin film by PECVD, and the thickness of the thin film is 1600 nm. The light window formed by the multiplication transmission film 92 can be used for the incidence of incident light. The passage area corresponding to the light window in the upper area is the source area of the device.

[0067] Please refer to FIG. 10. In this embodiment, in the above step S150, a P-type electrode 93 made of titanium (Ti), platinum (Pt), or gold (Au) material can be created by electron beam evaporation or a similar method. The P-type electrode 93 is located above the source region of the device. When forming a matrix, the P-type electrodes 93 of each detector in the single-photon detector matrix are spaced apart from each other. In this embodiment, since the P-type electrode 93 covers the entire source region of the device and can be used as a metal reflection mirror, the light incident from the substrate 00 side is reflected here, thereby enhancing the quantum efficiency of the detector.

[0068] In this embodiment, the substrate 00 can be thinned, and an N-type electrode 94 can be created over a large area on the back surface of the thinned substrate 00. After that, when forming a matrix, all the single-photon detectors in the matrix share the N-type electrode 94. This ensures the excellent ohmic contact characteristics and reliability of the single-photon detector.

[0069] In this embodiment, an inversion layer 60 is introduced into the epitaxial structure, and secondary adjustment control is performed on the distribution of the electric field based on the adjustment control of the charge layer 40, which can not only reduce the electric field at the periphery of the diffusion area but also effectively suppress problems such as edge breakdown.

[0070] As shown in FIG. 10, an embodiment of the present application further provides a single-photon detector created by the above manufacturing method. This single-photon detector includes a substrate 00 and a multi-layer epitaxial layer formed sequentially on the substrate 00. The multi-layer epitaxial layer includes a buffer layer 10, an absorption layer 20, a transition layer 30, a charge layer 40, a multiplication layer 50, an inversion layer 60, a transition layer 70, a window layer 80, and an ohmic contact layer 90. Among them, a curved diffusion area is formed in the ohmic contact layer 90 and the window layer 80. A platform structure is formed by etching the peripheries of some of the epitaxial layers on the substrate 00. In addition, the single-photon detector further includes an optical window formed on the back surface of the substrate 00 for the incidence of incident light. Furthermore, it includes a P-type electrode 93 formed on the ohmic contact layer 90 and an N-type electrode 94 formed on the back surface of the substrate 00.

[0071] In this embodiment, the inversion layer 60 can be used to perform secondary adjustment control on the distribution of the electric field based on the adjustment control of the charge layer 40. The introduced inversion layer 60 can lower the electric field at the periphery of the diffusion area and effectively suppress the problem of edge breakdown. Furthermore, since the single-photon detector provided by this embodiment can be obtained by primary diffusion and the epitaxial inversion layer 60, it does not require an etching platform and secondary epitaxy, and has advantages such as simple technology, high reliability, and high yield.

[0072] In this embodiment, the platform structure includes a first platform and a second platform. Among them, the first platform is the first platform formed in the upper area of the substrate 00 by etching the ohmic contact layer 90, the window layer 80, the transition layer 70, the inversion layer 60, the multiplication layer 50, the charge layer 40, the transition layer 30, the absorption layer 20, the buffer layer 10, and a part of the periphery of the substrate 00. The second platform is the second platform formed in the upper area of the multiplication layer 50 by etching the peripheries of the ohmic contact layer 90, the window layer 80, the transition layer 70, and the inversion layer 60.

[0073] By forming a first platform on the substrate 00, when forming a matrix based on a plurality of single-photon detectors subsequently, the single-photon detectors can be separated from each other. The etching width of the first platform can be between 1 μm and 100 μm, and for example, it can be 5 μm. That is, in the subsequent matrix, the pitch between the single-photon detectors can be between 1 μm and 100 μm.

[0074] By forming a second platform in the upper area of the multiplication layer 50, large-area absorption and small-size multiplication can be realized, and the beneficial effects of improving the efficiency of optical detection and reducing dark counts can be achieved.

[0075] In this embodiment, the single-photon detector further includes a passivation layer 91 grown on the first platform and the second platform. This passivation layer 91 is composed of a high-resistance polymer material, or can be composed of one or more of SiO2, SiN x , Al2O3. The thickness of the passivation layer 91 can be between 5 nm and 3000 nm. For example, using PECVD technology to create a SiN x thin film, and the thickness of the thin film is 500 nm. In this embodiment, the formed passivation layer 91 can achieve the effect of reducing the dark current by inactivating the platform.

[0076] In this embodiment, the optical window on the back surface of the substrate 00 includes a groove formed on the back surface of the substrate 00 and a multiplication transmission film 92 located in the groove. This concave groove is formed by etching the back surface of the substrate 00. The grown multiplication transmission film 92 can be silicon dioxide (SiO2), SiN x , or other similar optical thin films. For example, SiN by PECVD xIt is possible to create a thin film, and the thickness of the thin film is 1600 nm. The optical window formed by the doubling transmission film 92 can be used for the incidence of incident light. The passage area corresponding to the optical window in the upper area is the source area of the device.

[0077] In this embodiment, the P-type electrode 93 can be made of a material such as titanium (Ti), platinum (Pt), or gold (Au). Since the P-type electrode 93 covers the entire source area of the device and can be used as a metal reflection mirror, the light incident from the substrate 00 side is reflected here, thereby increasing the quantum efficiency of the detector.

[0078] In this embodiment, the inversion layer 60 can be composed of a combination of one or more materials among InP, InGaAs, InAlAs, InAlGaAs, and InGaAsP, and the inversion layer 60 can be a P-type doped layer. For example, it can be p-type InAlAs, specifically In 0.52 Al 0.48 As. The integral charge density of the inversion layer 60 is 2.0*e 12 / cm 2 ~4.0*e 12 / cm 2 For example, it can be 3.2*e 12 / cm 2 The thickness of the inversion layer 60 can be 150 nm to 300 nm, and the effects of electric field adjustment control and suppression of edge breakdown can be obtained.

[0079] In this embodiment, the substrate 00 can be a highly doped n-type InP substrate 00. The lattice coefficient of the buffer layer 10 is close to that of the substrate 00. For example, the buffer layer 10 can be an InP layer, and the thickness can be between 50 nm and 2000 nm. The range of the doping concentration of the buffer layer 10 is n-type 1*e 15 / cm 3 ~1*e 19 / cm 3It can be. For example, the thickness of the buffer layer 10 can be 1000 nm, and the doping concentration can be 1*e 18 / cm 3 It can be.

[0080] In this embodiment, the absorption layer 20 formed on the buffer layer 10 can be made of an n-type InGaAs material, and the thickness range can be 2000 nm to 2800 nm. For example, the thickness can be 2000 nm, and the doping is intrinsic n-type doping. The transition layer 30 can be an intrinsic layer, has a three-stage transition, can be made of an InGaAsP material, and its thickness range can be 10 nm to 300 nm. In this embodiment, the transition layer 30 can effectively improve the response of the device.

[0081] The thickness of the charge layer 40 can be 150 nm to 300 nm. The charge layer 40 can be made of an n-type InP material, and the integrated charge density of the charge layer 40 can be 2.4*e 12 / cm 2 ~4.8*e 12 / cm 2 It can be. For example, it can be 2.4*e 12 / cm 2 It can be, and the effect of suppressing edge breakdown can be obtained by adjusting the control electric field.

[0082] The multiplication layer 50 includes, but is not limited to, hole-type APD impact ionization materials such as InP, AlGaAsSb, and SiC. The characteristic of the hole-type APD impact ionization material is that the hole impact ionization coefficient of the material is higher than the electron ionization coefficient.

[0083] The multiplication layer 50 is the place where charge carriers generate impact ionization with the lattice in the device. The thickness range of the multiplication layer 50 can be 400 nm to 800 nm. For example, the multiplication layer 50 can be generated by an intrinsic InP material, and the thickness can be 500 nm.

[0084] The transition layer 70 includes, but is not limited to, a combination of one or more materials such as InP, InGaAs, InAlAs, InAlGaAs, InGaAsP, etc. The thickness range of the transition layer 70 is 500 nm to 700 nm, and for example, it can be 500 nm. The doping is intrinsic n-type or n-type light doping, and the doping range is doping n-type 1*e 15 / cm 3 ~1*e 17 / cm 3 and can be.

[0085] The diffusion concentration range in the window layer 80 and the ohmic contact layer 90 is 1*e 17 / cm 3 ~5*e 19 / cm 3 and is. The doping concentration range is 1*e 17 / cm 3 ~5*e 19 / cm 3 and is. The thickness of the window layer 80 is 1000 nm to 1500 nm. The thickness of the ohmic contact layer 90 is 100 nm to 200 nm, and for example, it can be 100 nm. The ohmic contact layer 90 is mainly used for P-type ohmic contact. The higher the doping concentration, the easier it is to achieve ohmic contact. The thickness is not an important parameter, but if it is too thick, it will affect the diffusion rate of P-type doping.

[0086] The single-photon detector provided by this embodiment is fabricated by the above single-photon detector manufacturing method and has the same characteristics as the detector created by the above manufacturing method. Therefore, for the parts not described in detail in this embodiment, reference can be made to the relevant descriptions in the above embodiment, and unnecessary explanations are omitted in this embodiment.

[0087] Please refer to FIG. 12. The embodiments of the present application further provide a single-photon detector matrix, which includes the single-photon detectors in any of the above embodiments, and a plurality of single-photon detectors are arranged in a matrix. The plurality of single-photon detectors are integrated into a readout circuit by flip-chip welding technology. The P-type electrodes 93 of each single-photon detector are spaced apart from each other, and the plurality of single-photon detectors share an N-type electrode 94.

[0088] In this embodiment, each single-photon detector in the matrix uses flip-chip welding technology. The N-type electrode 94 is connected to a high potential, and the P-type electrode 93 is connected to a low potential. Each single-photon detector is spaced apart from each other by a partition groove, and this partition groove is formed by a first platform formed by etching the epitaxial layer above the substrate 00 and a part of the substrate 00. The surface of the single-photon detector matrix is covered by the N-type electrode 94 and is driven by a readout circuit so that light is incident from the back of the device. The single-photon detector matrix realizes the function of detecting single photons through signal processing.

[0089] The single-photon detector matrix provided by this embodiment has the characteristics of a large photosensitive area and a small gain area, can realize large-area absorption and small-size multiplication, and can further reduce dark counts on the premise of improving the efficiency of optical detection.

[0090] The single-photon detector matrix provided by this embodiment is composed of the single-photon detectors in any of the above embodiments and has the same characteristics as the above single-photon detectors. Therefore, for the parts not described in detail in this embodiment, reference can be made to the relevant descriptions in the above embodiments, and redundant explanations are omitted in this embodiment.

[0091] Summarizing the above, the single-photon detector provided by the embodiment of the present application, its manufacturing method, and the single-photon detector matrix sequentially form a multi-layer epitaxial layer on one side of the provided substrate 00. The multi-layer epitaxial layer includes a buffer layer 10, an absorption layer 20, a transition layer 30, a charge layer 40, a multiplication layer 50, an inversion layer 60, a transition layer 70, a window layer 80, and an ohmic contact layer 90. And a curved diffusion area is formed in the ohmic contact layer 90 and the window layer 80 by diffusion technology, and an etching is performed on the periphery of a part of the epitaxial layer of the substrate 00 to form a platform structure, a light window is formed on the back surface of the substrate 00, and a P-type electrode 93 is formed on the ohmic contact layer 90, and an N-type electrode 94 is formed on the back surface of the substrate 00. This invention only adopts a primary diffusion process, and by combining the inversion layer 60, it can effectively reduce the electric field at the periphery of the diffusion area, and effectively suppress the problem of edge breakdown. Therefore, compared with the method that requires secondary diffusion in the prior art and the method that combines etching and secondary epitaxy in primary diffusion, the complexity of the technology can be reduced.

[0092] The specific embodiments of the present invention have been described above. However, the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention shall be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Description of Reference Numerals

[0093] 00 - Substrate; 10 - Buffer layer; 20 - Absorption layer; 30 - Transition layer; 40 - Charge layer; 50 - Multiplication layer; 60 - Inversion layer; 70 - Transition layer; 80 - Window layer; 90 - Ohmic contact layer; 91 - Passivation layer; 92 - Multiplication transmission film; 93 - P-type electrode; 94 - N-type electrode.

Claims

1. A method for manufacturing a single-photon detector, comprising: forming a multilayer epitaxial layer including a buffer layer, an absorption layer, a transition layer, a charge layer, a multiplication layer, an inversion layer, a transition layer, a window layer, and an ohmic contact layer that are epitaxially grown upward in sequence using epitaxial technology on one side of a provided substrate; forming a curved diffusion area having a bottom surface and a side peripheral surface extending upward from the periphery of the bottom surface, and the width of the side peripheral surface becoming wider from bottom to top, so that the cross-section is curved, in the ohmic contact layer and the window layer; forming a platform structure by etching the periphery of a part of the epitaxial layer on the substrate; forming a light window for incident light to enter on the back surface of the substrate; forming a P-type electrode on the ohmic contact layer and an N-type electrode on the back surface of the substrate; the transition layer being made of an InGaAsP material; the inversion layer being capable of reducing the electric field strength of the transition layer to suppress the edge breakdown effect, and being used for performing secondary adjustment control on the electric field distribution based on the adjustment control of the charge layer. A method for manufacturing a single-photon detector is characterized by the above.

2. The method for manufacturing a single-photon detector according to claim 1, wherein the inversion layer is composed of one or a combination of InP, InGaAs, InAlAs, InAlGaAs, and InGaAsP.

3. The integrated charge density of the inversion layer is 2.0*e １２ / cm ２ ~4.0*e １２ / cm ２ The method for manufacturing a single-photon detector according to claim 1, characterized in that it is within the range of

4. The method for manufacturing a single-photon detector according to claim 1, wherein the thickness of the charge layer is in the range of 150 nm to 300 nm, the thickness of the multiplication layer is in the range of 400 nm to 800 nm, and the thickness of the inversion layer is in the range of 150 nm to 300 nm.

5. The step of forming a curved diffusion area between the ohmic contact layer and the window layer includes: forming an etching layer on the ohmic contact layer; defining an etching area in the etching layer, and etching the etching layer based on the etching area to form an etching opening to expose a part of the ohmic contact layer from the etching opening; and performing P-type diffusion on the ohmic contact layer and the window layer by adopting a diffusion technique through the etching opening to form a curved diffusion area of P-type doping. The manufacturing method of the single-photon detector according to claim 1 is characterized in that.

6. The step of forming a platform structure by etching at least a part of the periphery of the epitaxial layer on the substrate includes: etching the periphery of the ohmic contact layer, the window layer, the transition layer, the inversion layer, the multiplication layer, the charge layer, the transition layer, the absorption layer, the buffer layer, and a part of the substrate to form a first platform in the upper area of the substrate; and etching the periphery of the ohmic contact layer, the window layer, the transition layer, and the inversion layer to form a second platform in the upper area of the multiplication layer. The manufacturing method of the single-photon detector according to claim 1 is characterized in that.

7. After the step of forming a second platform in the upper area of the multiplication layer by etching the peripheries of the ohmic contact layer, the window layer, the transition layer, and the inversion layer, the manufacturing method further includes forming a passivation layer on the first platform and the second platform, the passivation layer being composed of a high-resistance polymer material or composed of one or more of SiO ２ , SiN ｘ , Al ２ O ３ The method for manufacturing a single-photon detector according to claim 6, characterized in that it further comprises forming a passivation layer composed of one or more of the above.

8. The step of forming an optical window on the back surface of the substrate includes: performing an etching process on the back surface of the substrate with an etching thickness smaller than the thickness of the substrate; and growing a multiplication transmission film on the etched area of the substrate to form an optical window. The manufacturing method of the single-photon detector according to claim 1 is characterized in that.

9. A substrate, a buffer layer, an absorption layer, a transition layer, a charge layer, a multiplication layer, an inversion layer, a transition layer, a window layer, and an ohmic contact layer that are sequentially epitaxially grown upward on the substrate using epitaxial technology, wherein a curved diffusion area is formed in the ohmic contact layer and the window layer, and a part of the periphery of the epitaxial layer of the substrate is etched to form a platform structure, a multilayer epitaxial layer; a light window formed on the back surface of the substrate for incident light to enter; a P-type electrode formed on the ohmic contact layer; and an N-type electrode formed on the back surface of the substrate. Among them, the transition layer is made of InGaAsP material, and the inversion layer can reduce the electric field strength of the transition layer to suppress the edge breakdown effect and is used to perform secondary adjustment control on the electric field distribution based on the adjustment control of the charge layer. A single photon detector characterized by this.

10. The single photon detector according to claim 9, wherein the platform structure includes a first platform formed in the upper area of the substrate by etching the ohmic contact layer, the window layer, the transition layer, the inversion layer, the multiplication layer, the charge layer, the transition layer, the absorption layer, the buffer layer, and a part of the periphery of the substrate; and a second platform formed in the upper area of the multiplication layer by etching the periphery of the ohmic contact layer, the window layer, the transition layer, and the inversion layer.

11. The single photon detector further includes a passivation layer grown on the first platform and the second platform, the passivation layer is composed of a high-resistance polymer material, or SiO ２ , SiN ｘ , Al ２ O ３ The single photon detector according to claim 10, characterized in that it is composed of one or more of them.

12. The single photon detector according to claim 9, wherein the inversion layer is composed of one or more of InP, InGaAs, InAlAs, InAlGaAs, and InGaAsP.

13. The integrated charge density of the inversion layer is 2.0*e １２ / cm ２ ~4.0*e １２ / cm ２ The single-photon detector according to claim 9, characterized in that it is within the range of

14. The single photon detector according to claim 9, wherein the thickness of the charge layer is 150 nm to 300 nm, the thickness of the multiplication layer is 400 nm to 800 nm, and the thickness of the inversion layer is 150 nm to 300 nm.

15. Including a plurality of single-photon detectors according to claim 9, the plurality of single-photon detectors are arranged to form a matrix, the plurality of single-photon detectors are integrated into a readout circuit by flip-chip welding technology, the P-type electrodes of each single-photon detector are spaced apart from each other, and the plurality of single-photon detectors share an N-type electrode, characterized by a single-photon detector matrix.

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