InP-based back incidence coplanar electrode position sensitive detector

Abstract

The invention relates to an InP-based back incidence coplanar electrode position sensitive detector, which belongs to the technical field of photoelectric detectors, and is characterized in that an array is formed by a plurality of back incidence PSD units, the upper layers of the back incidence PSD units share a cathode, and an innovative structure capable of generating a better photoelectric effect is adopted; a common cathode layer, a P-type heavily doped layer for ohmic contact, a high-resistance silicon substrate layer and an InP dioxide substrate layer are sequentially arranged along the direction of incident light, a photosensitive area, a frame area and an isolation area are sequentially arranged on the lower portion of the high-resistance silicon substrate layer from inside to outside, and metal anodes are implanted in the positions of four end points of the InP dioxide substrate in contrast with the frame area. The structure greatly reduces the PSD array gap, eliminates the sampling blind area, has the advantages of simple signal processing, higher detection rate, high integration level, low cost, simple process and the like, and can be widely applied to the fields of wavefront detection, pose detection and the like to meet the various requirements of manufacturing super-large target surface, high-speed and high-density detectors and the like.

Description

Technical Field

[0001] The invention relates to the technical field of photoelectric position detectors, and in particular to an InP-based back-incident coplanar electrode position sensitive detector. Background Art

[0002] The two-dimensional pincushion position sensitive detector (PSD) detects the position of the laser spot based on the lateral photoelectric effect of semiconductor materials. PSD has the advantages of high position resolution, fast response speed, simple signal processing, etc. It is widely used in technical fields such as precision measurement, high-energy physics and target tracking. It is conducive to replacing the CCD in the Shack-Hartmann wavefront sensor as its core component, which can improve the rate of wavefront detection and the accuracy of wavefront restoration. It is also one of the most competitive and promising detectors in six-degree-of-freedom posture measurement.

[0003] However, existing position sensitive detectors are basically normal-incidence devices, that is, light is incident from the side where the photosensitive surface is located. When forming an array, the anode needs to be wired to the pad on the PCB substrate through wire bonding, so the area where the lead passes will sacrifice the sampling area, resulting in a sampling blind area. With the back-incidence structure, light is incident from the side where the cathode is located. The anode is rearranged through the redistribution wiring (RDL) technology, and then connected to the PCB substrate through flip-chip bonding. This can greatly reduce the spacing between adjacent PSDs, thereby eliminating the sampling blind area. At present, the spacing between adjacent PSDs in the normal-incidence PSD array is about 0.6mm. After adopting the back-incidence array, the spacing between adjacent devices can be reduced to less than 20μm, and the filling factor can reach more than 99.17%, which is 1.25 times higher than the normal incidence. Therefore, the back-incidence position sensitive detector (PSD) is a necessary condition for the production of ultra-large target surface, high-speed, and high-density detectors, which can effectively eliminate the sampling blind area.

[0004] For silicon-based detectors, due to their low absorption coefficient at an operating wavelength of 1μm, a sufficiently thick substrate is required to completely absorb the light. In order to ensure a certain responsiveness performance, the device thickness is generally not less than 300μm. However, the speed of the detector and the crosstalk between adjacent pixels when forming an array are limited by its thick thickness. Therefore, we propose an InP-based back-incident position-sensitive detector that can eliminate the sampling blind area in the normal-incident array. At the same time, based on the excellent optoelectronic properties of InP-based materials, the responsiveness and speed of the detector can be greatly improved compared to silicon-based detectors. At present, there is no InP-based back-incident position-sensitive detection device with no blind spots, high precision, small system size, and fast data transmission rate. The main technical difficulties lie in the complexity of the device structure design and the InP-based material process. Summary of the invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide an InP-based back-incident coplanar electrode position sensitive detector to solve the problems of large sampling blind area, complex process, low integration and high cost of existing detectors.

[0006] On the one hand, an embodiment of the present invention provides an InP-based back-incident coplanar electrode position sensitive detector, wherein the detector is an array composed of a plurality of back-incident PSD units; the electrodes of the plurality of PSD units are all located on the front side; the PSD units include the following arranged in sequence along the light incident direction:

[0007] High-resistance InP substrate region, used for light transmission and enhancing device strength;

[0008] N-type heavily doped region, used as ohmic contact;

[0009] Active area, used to build PI structure;

[0010] A depletion region is provided at the center of the upper portion of the active region, and the depletion region is located below the N-type heavily doped region; a photosensitive region is provided below the depletion region, and a frame region is provided at the lower edge of the photosensitive region;

[0011] The photosensitive region is used as a movable area of ​​the light spot to produce a lateral photoelectric effect and generate electron-hole pairs;

[0012] The border region is used to absorb electrons;

[0013] Filling silicon dioxide in other areas of the active region except the depletion region, the photosensitive region and the border region as a buried layer;

[0014] implanting metal anodes in the buried layer at positions corresponding to the four end points of the border area;

[0015] A cathode is implanted in a buried layer located below the N-type heavily doped region and outside the depletion layer; the cathode corresponds to the anode in one-to-one position.

[0016] Based on the further improvement of the above detector, the N-type heavily doped region is formed by diffusion doping SiH 4 form.

[0017] Based on the further improvement of the above detector, the depletion region is formed by post-growth processing of InP material.

[0018] Based on the further improvement of the above detector, the photosensitive area is a pillow shape, the frame area includes four arcs, and the four arcs form a pillow shape; the frame area and the photosensitive area, according to Gear's theorem, have the following relationship:

[0019] In the formula,

[0020] a is the radius of curvature of the circular arc of the border area, wherein the size of the effective collection area of ​​the light spot is preset in the photosensitive area, and the effective collection area is a square inscribed in the pillow-shaped photosensitive area; the radius of curvature of the four identical circles tangent to the outside of the center points of each side line of the square and tangent to each other is the minimum value of the radius of curvature of the circular arc of the border area;

[0021] b is the width of the border area, which shall not exceed 100 μm.

[0022] r1 is the block resistance of the border area,

[0023] r2 is the sheet resistance of the photosensitive area.

[0024] Based on the further improvement of the above detector, the border area is composed of a concentration range of 1e19-1e20cm -3 The Zn ions are heavily doped into InGaAs for P-type formation.

[0025] Based on the further improvement of the above detector, the photosensitive area is formed by lightly doping InGaAs with Zn ions into a P-type, and its doping concentration range depends on the block resistance of the border area and the photosensitive area, as well as the doping concentration of the border area.

[0026] Based on the further improvement of the above InP-based back-incident coplanar electrode position sensitive detector, the thickness of the photosensitive area is determined according to the following formula to completely absorb the incident light:

[0027] i=1 / α, where,

[0028] i is the thickness of the photosensitive area,

[0029] α is the absorption coefficient.

[0030] Based on the further improvement of the above detector, the anode is made of Ti / Au alloy.

[0031] Based on the further improvement of the above detector, the cathode is made of Au / Zn alloy.

[0032] On the other hand, the present invention provides a method for preparing an InP-based back-incident coplanar electrode position sensitive detector, the method comprising the following steps:

[0033] An N-type heavily doped ohmic contact layer, a depletion layer, a photosensitive layer, and a frame layer are sequentially grown on a high-resistance substrate by metal organic chemical vapor deposition to form an epitaxial wafer;

[0034] After cleaning the epitaxial wafer, a layer of silicon dioxide mask is grown by low temperature chemical vapor deposition or enhanced plasma chemical vapor deposition;

[0035] A wet etching method is used to etch a blank area between the silicon dioxide mask and the frame layer until the photosensitive layer is exposed;

[0036] A layer of silicon dioxide is deposited on the surface of the epitaxial wafer by using enhanced plasma chemical vapor deposition, and anode lead holes are photoetched;

[0037] Photolithography is used to pattern the electrodes, and metal is evaporated to form the anode;

[0038] A layer of SiO2 is deposited on the surface of the epitaxial wafer, an etching window is photolithographically formed, and table etching is performed until the N-type heavily doped ohmic contact layer is exposed, forming a border region, a photosensitive region, and a depletion region;

[0039] A layer of silicon dioxide is deposited on the surface by using enhanced plasma chemical vapor deposition, the anode is kept exposed, and a cathode lead hole is photoetched;

[0040] Photolithography is used to pattern the electrodes, and metal is evaporated to form the cathode;

[0041] Dissociation completes device fabrication.

[0042] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0043] 1. Starting from the principle level of the device, the InP-based back-incident coplanar electrode position sensitive detector structure designed by the present invention can meet the needs of making ultra-large target area, high-speed, and high-density detectors in the field of wavefront detection and posture detection. Compared with the normal-incident PSD array, it eliminates the sampling blind area in the array PSD.

[0044] 2. Compared with the silicon-based back-incident PSD, the InP-based back-incident PSD of the present invention can achieve nA-level dark current at an operating wavelength of 1μm based on the excellent optoelectronic properties of InP materials. The device performance is superior to that of the silicon-based back-incident PSD in terms of responsiveness and resolution indicators. Based on the characteristics of InP-based materials, the light absorption coefficient is high at an operating wavelength of 1μm, the active area can be made very thin, and it has many advantages such as working under low bias voltage, low energy consumption, small crosstalk between pixels after forming an array, high responsiveness, and high bandwidth.

[0045] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be achieved and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. In the entire drawings, the same reference symbols represent the same components;

[0047] Figure 1 This is a cross-sectional view of the InP-based back-incident PSD of the present invention.

[0048] Figure 2 Schematic diagram of the method for determining the minimum value of the curvature radius of the border area according to the present invention.

[0049] Figure 3 It is a schematic diagram of the bottom structure (photosensitive area, frame area, anode, cathode, buried layer, high-resistance InP substrate area) of the InP-based back-incident PSD of the present invention.

[0050] Figure 4 It is a schematic diagram of the InP-based back-incident PSD array of the present invention.

[0051] Figure 5 This is a flow chart for preparing the InP-based back-incident PSD of the present invention.

[0052] Figure 6 This is a comparison chart of the light absorption coefficients corresponding to different components of the materials used in the present invention.

[0053] Figure 7 This is a schematic diagram of the device structure after the first step of the InP-based PSD preparation process according to an embodiment of the present invention is completed.

[0054] Figure 8 This is a schematic diagram of the device structure after the second step of the InP-based PSD preparation process according to an embodiment of the present invention is completed.

[0055] Figure 9 This is a schematic diagram of the device structure after the third step of the InP-based PSD preparation process according to an embodiment of the present invention is completed.

[0056] Figure 10 This is a schematic diagram of the device structure after the fourth step of the InP-based PSD preparation process according to an embodiment of the present invention is completed.

[0057] Figure 11 This is a schematic diagram of the device structure after the fifth step of the InP-based PSD preparation process according to an embodiment of the present invention is completed.

[0058] Figure 12 This is a schematic diagram of the device structure after the sixth step of the InP-based PSD preparation process according to an embodiment of the present invention is completed.

[0059] Figure 13 This is a schematic diagram of the device structure after the seventh step of the InP-based PSD preparation process according to an embodiment of the present invention is completed.

[0060] Figure 14 This is a schematic diagram of the device structure after the eighth step of the InP-based PSD preparation process according to an embodiment of the present invention is completed.

[0061] Reference numerals:

[0062] 1-high resistance InP substrate region; 2-N-type heavily doped region; 3-active region; 4-depletion layer;

[0063] 5-photosensitive area; 6-frame area; 7-buried layer; 8-anode; 9-cathode. DETAILED DESCRIPTION

[0064] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0065] A specific embodiment of the present invention discloses an InP-based back-incident coplanar electrode position sensitive detector, wherein the detector is an array composed of a plurality of back-incident PSD units; the electrodes of the plurality of PSD units are all located on the front side; the PSD units include the following arranged in sequence along the light incident direction:

[0066] High-resistance InP substrate region, used for light transmission and enhancing device strength;

[0067] N-type heavily doped region, used as ohmic contact;

[0068] Active area, used to build PI structure;

[0069] A depletion region is provided at the center of the upper portion of the active region, and the depletion region is located below the N-type heavily doped region; a photosensitive region is provided below the depletion region, and a frame region is provided at the lower edge of the photosensitive region;

[0070] The photosensitive region is used as a movable area of ​​the light spot to produce a lateral photoelectric effect and generate electron-hole pairs;

[0071] The border region is used to absorb electrons;

[0072] Filling silicon dioxide in other areas of the active region except the depletion region, the photosensitive region and the border region as a buried layer;

[0073] implanting metal anodes in the buried layer at positions corresponding to the four end points of the border area;

[0074] A cathode is implanted in a buried layer located below the N-type heavily doped region and outside the depletion region; the cathode corresponds to the anode in one-to-one position.

[0075] Specifically, Figure 1 As shown, this embodiment adopts a typical PIN type photodiode structure, including: a high-resistance InP substrate region 1, an N-type heavily doped region 2, an active region 3, a depletion layer 4, a photosensitive region 5, a frame region 6, a buried layer 7, an anode 8, and a cathode 9.

[0076] Furthermore, the N-type heavily doped region is formed by diffusion doping SiH 4 form.

[0077] Preferably, a layer of N-type heavily doped region 2 is grown on the high-resistance InP substrate region 1, and SiH4 is used to perform N-type heavy doping in InGaAsP with a thickness of about 400-500nm for ohmic contact.

[0078] Furthermore, the depletion region is formed by post-growth processing of InP material.

[0079] Specifically, a depletion region 4 made of InP material is grown in the N-type heavily doped region, preferably with a thickness of about 300 nm, to generate an electric field to separate the photogenerated carriers.

[0080] Furthermore, the photosensitive area is a pillow shape, the frame area includes four arcs, and the four arcs form a pillow shape; the frame area and the photosensitive area, according to Gear's theorem, have the following relationship:

[0081] In the formula,

[0082] a is the radius of curvature of the circular arc of the border area, wherein the size of the effective collection area of ​​the light spot is preset in the photosensitive area, and the effective collection area is a square inscribed in the pillow-shaped photosensitive area; the radius of curvature of the four identical circles tangent to the outside of the center points of each side line of the square and tangent to each other is the minimum value of the radius of curvature of the circular arc of the border area;

[0083] b is the width of the border area, which shall not exceed 100 μm.

[0084] r1 is the block resistance of the border area,

[0085] r2 is the sheet resistance of the photosensitive area.

[0086] Specifically, the pillow-shaped structure PSD is proposed based on Gear's theorem. In 1969, Gear proposed a boundary condition that does not affect the electric field distribution in a large area, which is later called Gear's theorem. According to Gear's theorem, the border area curvature radius a, border area width b, border area square resistance r1, and photosensitive area square resistance r2 of the pillow-shaped PSD have the following relationship:

[0087]

[0088] The measured two-dimensional position coordinates can be output without distortion.

[0089] Preferably, according to the content of Gear's theorem, when designing a PSD, the width b of the border area generally does not exceed 100 μm, otherwise the current transmission efficiency is affected, resulting in a deterioration in the linearity of the device output result.

[0090] Preferably, after determining the border area width b, the border area curvature radius a is given (not too small, otherwise the invalid device area will increase). Figure 2 As shown in the figure, the central dotted square area represents the effective spot collection area required by the device application, and the side length of the square is a preset value. Draw four lines of the same radius on the four sides of the square, which are tangent to each other and tangent to the center point of one side of the square respectively, then Figure 2 The radius a of any circle in is the minimum value of the curvature radius a of the border area. The four tangent arcs form a quadrilateral, which is the border area 2 with the minimum curvature radius. The line width b of the border area is the width of the border area.

[0091] Preferably, in this example, the border area curvature radius a is taken as 1 cm, and the ratio of the border area curvature radius a to the border area width b is 100, that is, the ratio of the square resistance of the border area 6 and the photosensitive area 5 is 100.

[0092] Furthermore, the border area has a concentration range of 1e19-1e20cm -3 The Zn ions are heavily doped into InGaAs for P-type formation.

[0093] Furthermore, the photosensitive region is formed by lightly doping InGaAs with Zn ions into a P-type state, and the doping concentration range depends on the block resistance of the border region and the photosensitive region, as well as the doping concentration of the border region.

[0094] Preferably, the doping concentration of the border region 6 is set to 1e19 cm -3 The above is adjusted according to the 100-fold square resistance relationship to obtain the doping concentration of the photosensitive region 5, so that it ranges from 1e15 to 1e17 cm -3 ,The performance can then be further optimized by combining simulation and experiment.

[0095] Specifically, a layer with a concentration range of 1e15-1e17 cm is grown above the depletion region. -3 The Zn ion P-type doped InGaAs layer has a concentration range of 1e19-1e20cm -3 The Zn ion P-type heavily doped InGaAs layer is formed by etching, photolithography and other processes to form a photosensitive area 5 in the first layer and a frame area 6 in the second layer. The photosensitive area 5 is located in the middle area, and the frame area 6 covers the edge of the photosensitive area 5. The photosensitive area 5 is the area where the light spot can move. When the light spot is irradiated to the photosensitive area 5, electron-hole pairs are generated in the radiation area. The actual position of the light spot can be calculated by the current values ​​of the four corners on the frame area 6 using the photoelectric lateral effect. There is a concentration difference between the frame area 6 and the photosensitive area 5, which is conducive to better generating the lateral photoelectric effect and absorbing the photogenerated carriers.

[0096] Furthermore, the thickness of the photosensitive region is determined according to the following formula so that the incident light is completely absorbed:

[0097] i=1 / α, where,

[0098] i is the thickness of the photosensitive area,

[0099] α is the absorption coefficient.

[0100] Specifically, as shown in the figure, the material structure of the back-incident PSD is a quaternary material composed of four elements: In, Ga, As, and P. 1-x Ga x As y P 1-y , (x and y are element composition coefficients) can be regarded as a compound of four binary materials InP, InAs, GaAs and GaP. By adjusting the composition of the four elements, its band structure can be changed. The band gap of InGaAsP is generally calculated using the following bandgap width formula:

[0101] Eg(x,y)(eV)=1.35+0.642x-1.101y+0.785x 2 +0.101y 2 -0.159xy-0.28x 2 y+0.109xy 2 ,,

[0102] Where Eg(x, y) is the bandgap width of the material being solved, and (eV) is the unit of the bandgap width.

[0103] In the epitaxial growth process of manufacturing devices, In is usually required 1-x Ga x As y P 1-y The material is lattice-matched with InP to avoid stress, and x and y satisfy the formula:

[0104] x=0.4526y / (1-0.031y),0<y≤1,

[0105] Substituting this formula into the bandgap width formula, we get In that matches the InP lattice. 1-x Ga x As y P 1-y The bandgap width of the material is only related to x or y. In this embodiment, x is eliminated and expressed as the following formula:

[0106] Eg(y)(eV)=1.35-0.775y+0.149y 2 ,

[0107] Since InGaAsP material is a direct bandgap material, the relationship between its bandgap wavelength and forbidden band width is expressed as the following formula:

[0108] λ g (μm)=hc / Eg=1.2398 / Eg.

[0109] The λ obtained from the above formula is g is the cut-off wavelength of the incident light, h is Planck's constant, c is the speed of light, and the light absorption coefficient α can be obtained by looking up the relationship table between them and the light absorption coefficient, thereby determining the material thickness of the photosensitive area according to the relationship i=1 / α.

[0110] Preferably, in this embodiment, the photosensitive area adopts In 0.53 Ga 0.47 As material as an example, the photosensitive area material is InGaAs, zinc (Zn) is used for P-type light doping, and the commonly used dopant is Zn (C 2 H 5 ) 2 or Zn(CH 3 ) 2 , namely diethyl zinc (DEZn) or dimethyl zinc (DMZn). Here, the thickness is determined according to the absorption coefficient of InGaAs material to light. 0.53 Ga 0.47 As material is taken as an example, this component can match the InP lattice. 0.53 Ga 0.47 The absorption coefficient of As at a wavelength of 1030 nm is about 3.028 μm -1 , that is, its absorption depth is about 0.33μm, so a 300-500nm thick In 0.53 Ga 0.47 As can completely absorb the light.

[0111] Specifically, Figure 3 As shown, in one embodiment of the present invention, the bottom of the back-incident PSD is a photosensitive area 5, surrounded by a pillow-shaped frame area 6, and the current values ​​collected by the four anodes are I1, I2, I3, and I4 respectively. The position coordinates X and Y of the light spot can be calculated by the following formula:

[0112]

[0113] Compared with traditional CCD devices, it can directly obtain the position information of the light spot through current, with simple signal processing and high detection rate.

[0114] Furthermore, the anode is made of Ti / Au alloy.

[0115] Furthermore, the cathode is made of Au / Zn alloy.

[0116] Specifically, there are coplanar metal electrodes on the back of the device, that is, the anode and cathode are on the same surface, wherein the anode is a Ti / Au electrode with a thickness of preferably about 300nm for current extraction, and the cathode is an Au / Zn alloy electrode with a thickness equal to the sum of the thickness of the depletion layer, the photosensitive area, the frame area, and the anode.

[0117] Specifically, when applied, the metal anode is rearranged through redistribution wiring (RDL) and then connected to the PCB substrate through flip-chip bonding; specifically, a layer of epoxy resin is laid at the bottom of the PSD array, and a metal line pattern is photoetched according to the position of the fan-out line of each anode point of each PSD, and one end of each line is connected to an anode of the corresponding PSD, and the other end is connected to a corresponding bump, and all bumps are bonded to the PCB board, thereby realizing the bump bonding of the PSD array and the PCB board. The purpose of this is to solve the problem that the positions of adjacent PSD anodes in the PSD array are too close, and direct connection of bumps is prone to bump contact, and the uniform arrangement of bumps is achieved through redistribution technology. The corresponding bumps are passed under the PSD anode to guide the current into the signal processing circuit below. This three-dimensional packaging method of bump bonding does not require additional lead fan-out in a two-dimensional plane, which significantly reduces the gap between each PSD.

[0118] The embodiments of the present invention cleverly eliminate the sampling blind spots that exist in applications in the fields of wavefront detection and posture detection while realizing position detection. The design method is simple, the structure is compact, and it is very practical. It is compatible with CMOS technology, has excellent performance, and has low process difficulty. It can be used for large-scale PSD integrated chips.

[0119] Since the thickness of silicon-based back-incident PSD is relatively thick, generally reaching about 300-500μm, the generated photogenerated carriers diffuse laterally, and there is no good way to suppress them, resulting in large crosstalk between arrays. For InP-based back-incident PSD, since the active area is relatively thin, about 1-2μm, the crosstalk between array pixels can be preferably eliminated by adding isolation rings, etc., thereby suppressing the crosstalk to an extremely low level.

[0120] Another embodiment of the present invention, as Figure 5 As shown, a method for preparing an InP-based back-incident coplanar electrode position sensitive detector is disclosed, and the process is as follows:

[0121] Step S1: On a high-resistance InP substrate, an N-type heavily doped ohmic contact layer, a depletion layer, a photosensitive layer, and a frame layer are sequentially grown by metal organic chemical vapor deposition (MOCVD) to form an epitaxial wafer.

[0122] Step S2: After cleaning the epitaxial wafer, a layer of silicon dioxide mask is grown by low-temperature chemical vapor deposition (CVD) or plasma enhanced chemical vapor deposition (PECVD) method.

[0123] Step S3: using a wet etching method to etch out a blank area between the silicon dioxide mask and the frame layer until the photosensitive layer is exposed.

[0124] Step S4: using PECVD to deposit a layer of silicon dioxide on the surface of the etched blank area, and photoetching the anode lead hole.

[0125] Step S5: Photolithography to form an electrode pattern, and evaporation of a titanium-gold alloy to form an anode.

[0126] Step S6: Photolithography is performed to form an etching window until the N-type heavily doped ohmic contact layer is exposed, thereby forming a frame area, a photosensitive area, and a depletion layer.

[0127] Step S7: Use PECVD to deposit a layer of silicon dioxide on the surface, keep the anode exposed, and photoetch out the cathode lead hole.

[0128] Step S8: Photolithography to form an electrode pattern, and evaporation of gold-zinc alloy to form a cathode.

[0129] Step S9: dissociation, completing device fabrication.

[0130] Specifically, in the process of preparing the InP-based back-incident PSD in this embodiment, the device placement orientation is consistent with the prior art.

[0131] The specific process of preparing an InP-based back-incident coplanar electrode position sensitive detector is as follows:

[0132] Step 1: Figure 7 As shown, an N-type InGaAsP contact layer, an i-InP depletion layer, a P-InGaAs photosensitive layer, and a P+-InGaAs layer are sequentially grown on a high-resistance InP substrate by metal organic chemical vapor deposition (MOCVD) to form an epitaxial wafer.

[0133] Step 2: If Figure 8 As shown, the epitaxial wafer is cleaned, and a layer of SiO is grown in sequence by low-temperature chemical vapor deposition (CVD) or plasma enhanced chemical vapor deposition (PECVD) method. 2 film, as an etching mask.

[0134] Step 3: If Figure 9 As shown, the photolithography pattern is formed, an etching window is selected on the SiO2 mask, and the device border area is produced by a wet etching method.

[0135] Step 4: Figure 10As shown, a layer of SiO2 is deposited on the surface by PECVD, and an etching window is photolithographically carved and then etched to form a lead hole.

[0136] Step 5: Figure 11 As shown, the electrode pattern is photolithographically formed, and a titanium-gold alloy is evaporated to form an anode.

[0137] Step 6: Figure 12 As shown, a layer of SiO2 is deposited on the surface by PECVD, an etching window is photolithographically formed, and the mesa is etched. The inductively coupled plasma (ICP) etching method is used to etch in a Cl2 / CH4 / H2 atmosphere until the N+ type InGaAsP layer is exposed. If the mesa is exposed to the atmosphere for a long time, oxides will be generated. Therefore, after etching, the mesa should be repaired by chemical etching, and then immediately placed in a vacuum chamber to grow a passivation film.

[0138] Step 7: Figure 13 As shown, a layer of SiO2 is deposited on the surface by PECVD, and an etching window is photolithographically carved and then etched to form a lead hole.

[0139] Step 8: Figure 14 As shown, the electrode pattern is photolithographically formed, and a gold-zinc alloy is evaporated to form a cathode.

[0140] Step 9: Dissociation, the device is completed.

[0141] At this point, the structure of a back-incident position sensitive detector is completed.

[0142] Those skilled in the art will appreciate that all or part of the processes of the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, wherein the computer-readable storage medium is a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0143] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An InP-based back-incident coplanar electrode position sensitive detector, It is characterized in that The detector is an array composed of a plurality of back-incident PSD units; the electrodes of the plurality of PSD units are all located on the front side; the PSD units include the following arranged in sequence along the light incident direction: High-resistance InP substrate region, used for light transmission and enhancing device strength; N-type heavily doped region, used as ohmic contact; Active area, used to build PI structure; A depletion region is provided at the center of the upper portion of the active region, and the depletion region is located below the N-type heavily doped region; a photosensitive region is provided below the depletion region, and a frame region is provided at the lower edge of the photosensitive region; The photosensitive region is used as a movable area of ​​the light spot to produce a lateral photoelectric effect and generate electron-hole pairs; The border region is used to absorb electrons; Filling silicon dioxide in other areas of the active region except the depletion region, the photosensitive region and the border region as a buried layer; implanting metal anodes in the buried layer at positions corresponding to the four end points of the border area; A cathode is implanted in a buried layer located below the N-type heavily doped region and outside the depletion layer; the cathode corresponds to the anode in one-to-one position.

2. The InP-based back-incident coplanar electrode position sensitive detector according to claim 1, It is characterized in that The N-type heavily doped region is formed by diffusion doping SiH in InGaAsP. 4 form.

3. The InP-based back-incident coplanar electrode position sensitive detector according to claim 2, It is characterized in that The depletion region is formed by post-growth processing of InP material.

4. The InP-based back-incident coplanar electrode position sensitive detector according to claim 3, It is characterized in that The photosensitive area is pillow-shaped, and the frame area includes four arcs, which form a pillow shape; according to Gear's theorem, the frame area and the photosensitive area have the following relationship: In the formula, a is the radius of curvature of the circular arc of the border area, wherein the size of the effective collection area of ​​the light spot is preset in the photosensitive area, and the effective collection area is a square inscribed in the pillow-shaped photosensitive area; the radius of curvature of the four identical circles tangent to the outside of the center points of each side line of the square and tangent to each other is the minimum value of the radius of curvature of the circular arc of the border area; b is the width of the border area, which shall not exceed 100 μm. r1 is the block resistance of the border area, r2 is the sheet resistance of the photosensitive area.

5. The InP-based back-incident coplanar electrode position sensitive detector according to claim 4, It is characterized in that The border area is composed of a concentration range of 1e19-1e20cm -3 The Zn ions are heavily doped into InGaAs for P-type formation.

6. The InP-based back-incident coplanar electrode position sensitive detector according to claim 5, It is characterized in that The photosensitive region is formed by lightly doping InGaAs with Zn ions into a P-type state, and the doping concentration range depends on the square resistance of the border region and the photosensitive region, as well as the doping concentration of the border region.

7. The InP-based back-incident coplanar electrode position sensitive detector according to claim 6, It is characterized in that The thickness of the photosensitive area is determined according to the following formula to completely absorb the incident light: i=1 / α, where, i is the thickness of the photosensitive area, α is the absorption coefficient.

8. The InP-based back-incident coplanar electrode position sensitive detector according to claim 7, It is characterized in that The anode is made of Ti / Au alloy.

9. The InP-based back-incident coplanar electrode position sensitive detector according to claim 8, It is characterized in that The cathode is made of Au / Zn alloy.

10. A method for preparing an InP-based back-incident coplanar electrode position sensitive detector, It is characterized in that The method comprises the following steps: An N-type heavily doped ohmic contact layer, a depletion layer, a photosensitive layer, and a frame layer are sequentially grown on a high-resistance substrate by metal organic chemical vapor deposition to form an epitaxial wafer; After cleaning the epitaxial wafer, a layer of silicon dioxide mask is grown by low temperature chemical vapor deposition or enhanced plasma chemical vapor deposition; A wet etching method is used to etch a blank area between the silicon dioxide mask and the frame layer until the photosensitive layer is exposed; A layer of silicon dioxide is deposited on the surface of the epitaxial wafer by using enhanced plasma chemical vapor deposition, and anode lead holes are photoetched; Photolithography is used to pattern the electrodes, and metal is evaporated to form the anode; A layer of SiO2 is deposited on the surface of the epitaxial wafer, an etching window is photolithographically formed, and table etching is performed until the N-type heavily doped ohmic contact layer is exposed, forming a border region, a photosensitive region, and a depletion region; A layer of silicon dioxide is deposited on the surface by using enhanced plasma chemical vapor deposition, the anode is kept exposed, and a cathode lead hole is photoetched; Photolithography is used to pattern the electrodes, and metal is evaporated to form the cathode; Dissociation completes device fabrication.

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