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CN116230800B - A near-infrared single-photon array detector and a method for preparing the same - Google Patents

A near-infrared single-photon array detector and a method for preparing the same Download PDF

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CN116230800B
CN116230800B CN202310169970.3A CN202310169970A CN116230800B CN 116230800 B CN116230800 B CN 116230800B CN 202310169970 A CN202310169970 A CN 202310169970A CN 116230800 B CN116230800 B CN 116230800B
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layer
electrode
diffusion
isolation region
electrode window
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CN116230800A (en
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王兴
乔凯
尹飞
郭可飞
汪韬
李鸣
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XiAn Institute of Optics and Precision Mechanics of CAS
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XiAn Institute of Optics and Precision Mechanics of CAS
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
    • H10F30/20—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors
    • H10F30/21—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation
    • H10F30/22—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes
    • H10F30/225—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes the potential barrier working in avalanche mode, e.g. avalanche photodiodes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
    • H10F39/10—Integrated devices
    • H10F39/103—Integrated devices the at least one element covered by H10F30/00 having potential barriers, e.g. integrated devices comprising photodiodes or phototransistors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F71/00—Manufacture or treatment of devices covered by this subclass
    • H10F71/127—The active layers comprising only Group III-V materials, e.g. GaAs or InP
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F77/00—Constructional details of devices covered by this subclass
    • H10F77/10—Semiconductor bodies
    • H10F77/12—Active materials
    • H10F77/124—Active materials comprising only Group III-V materials, e.g. GaAs
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F77/00—Constructional details of devices covered by this subclass
    • H10F77/20—Electrodes
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
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    • H10F77/30—Coatings
    • H10F77/306—Coatings for devices having potential barriers
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    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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Abstract

The invention discloses a near infrared single photon array detector and a preparation method thereof, which are used for solving the technical problems of complex preparation process, poor crosstalk prevention isolation effect and the like of the traditional single photon array detector. The array detector comprises a substrate layer, an epitaxial layer arranged on the upper surface of the substrate layer and an anti-reflection layer arranged on the lower surface of the substrate layer, wherein the epitaxial layer comprises a buffer layer, an absorption layer, a gradual change layer, a charge layer and a cap layer which are sequentially grown from bottom to top, the buffer layer is close to the substrate layer, a passivation layer is arranged on one side of the cap layer far away from the charge layer, a plurality of second electrode windows and a plurality of third electrode windows are uniformly distributed on the passivation layer at intervals, a pixel anode metal electrode is arranged on the inner side of each second electrode window, an isolation region electrode is arranged on the inner side of each third electrode window, an active diffusion region is formed by the cap layer and the outer side of the second electrode window, a diffusion isolation region is formed by surrounding the cap layer and the third electrode windows, and the diffusion isolation regions are of step structures, and the depth of the diffusion isolation regions is identical with that of the active diffusion regions.

Description

Near-infrared single photon array detector and preparation method thereof
Technical Field
The invention relates to a single photon semiconductor device, in particular to a near infrared single photon array detector and a preparation method thereof.
Background
At present, the device capable of realizing single photon array detection mainly comprises a photomultiplier tube (PMT), a Superconducting Nanowire (SNSPD), a photoelectric avalanche diode (APD) and the like, wherein the PMT has the problems of large volume, high manufacturing cost, high-voltage operation of kilovolts, easiness in magnetic field influence and the like, the SNSPD usually needs to work in a temperature region below liquid helium (4.2K), the application range of the SNSPD is limited, and the single photon device based on a Geiger mode has the advantages of small volume, low working voltage, easiness in integration and the like, and is widely applied to the fields of quantum communication, biochemistry, space detection, laser radar and the like. The geiger mode avalanche diode array manufactured by InGaAs/InP has the advantages of good response characteristics at the wavelength of 1.55 mu m, good safety to human eyes, good atmospheric transmissibility and the like because the response band covers 0.9-1.7 mu m, and the device is widely paid attention to and rapidly developed in various fields in recent years.
At present, the InGaAs/InP single photon array detector still has a series of problems, which cause the preparation difficulty and the cost to be high. Meanwhile, as the distance between the adjacent pixels of the detector is small, a large number of carriers generated under the avalanche effect easily enter the adjacent pixels in a diffusion mode, so that electric crosstalk between the pixels is caused, and resolution is reduced and miscounting rate is improved.
In order to suppress the electrical crosstalk between the pixels, a P-type isolation region is added between adjacent pixels in the prior art, and the P-type isolation region is positioned between two adjacent P-type doped regions, so that carriers which are laterally diffused can be prevented from entering the adjacent pixels. However, as the size of the array detector increases, the inter-pixel electrical crosstalk is further exacerbated as the pixel pitch is further reduced. Therefore, in the preparation process of the InGaAs/InP single photon array detector, a P-type doped region with a step-type structure is required to be formed, and the structure can effectively reduce the edge breakdown effect and further reduce the dark count rate. In the existing preparation process, two high-temperature Zn diffusion processes are usually carried out, wherein the doped region formed by the first Zn diffusion is larger and the doped concentration is lower, the doped region formed by the second Zn diffusion is smaller and the doped concentration is higher, a step-type P-type doped region is formed in the InP cap layer, and meanwhile, a P-type isolation region is formed in the second Zn diffusion, but the process also has the following problems:
(1) The P-type doped region with the step structure is formed by adopting a twice Zn diffusion process, the process is complex, and defects can be introduced into the material by multiple times of high-temperature treatment, so that the performance of the device is reduced.
(2) Because the current P-type isolation region is a shallow groove structure formed on the InP cap layer, and the region doping is carried out by adopting a single Zn diffusion method, the depth of Zn doping in the P-type isolation region is shallower, the isolation effect on transverse diffusion carriers at the deeper position of the cap layer multiplication region is poor, and the device edge breakdown inhibition effect is limited.
Disclosure of Invention
The invention aims to provide a near infrared single photon array detector and a preparation method thereof, which are used for solving the technical problems of complex preparation process, poor crosstalk prevention isolation effect and the like of the traditional single photon array detector.
In order to achieve the above object, the present invention provides a near infrared single photon array detector, which is characterized in that:
The anti-reflection layer is provided with a plurality of first electrode windows and a plurality of pixel incidence windows which are distributed at intervals, wherein the bottoms of the first electrode windows are contacted with the lower surface of the substrate layer, and pixel cathode metal electrodes are arranged in the first electrode windows;
The epitaxial layer comprises a buffer layer, an absorption layer, a gradual change layer, a charge layer and a cap layer which are sequentially grown from bottom to top, wherein the buffer layer is close to the substrate layer;
A plurality of second electrode windows and a plurality of third electrode windows are uniformly distributed on the passivation layer at intervals, a pixel anode metal electrode is arranged on the inner side of each second electrode window, and an isolation region electrode is arranged on the inner side of each third electrode window;
the depth of the second electrode window is the same as that of the third electrode window, and the bottoms of the second electrode window and the third electrode window are both positioned in the cap layer;
The diffusion isolation region is of a step structure, the depth of the diffusion isolation region is the same as that of the active diffusion region, and the structural design can isolate transverse diffusion carriers at the deeper position of the multiplication layer on one hand, and can optimize electric field distribution at the edge of the center junction on the other hand, so that the edge breakdown of the device can be well restrained.
Further, the diffusion isolation region comprises a shallow isolation region and a deep isolation region which are arranged from top to bottom, and the width of the shallow isolation region is larger than that of the deep isolation region. By the wider shallow isolation region, the curvature radius of the diffusion isolation region is increased, and further advanced breakdown at the junction edge is better suppressed.
Further, the active diffusion region is of a step structure and comprises a shallow diffusion region and a deep diffusion region which are arranged from top to bottom, the width of the shallow diffusion region is larger than that of the deep diffusion region, the curvature radius of the active diffusion region is increased through the wider shallow diffusion region, and early breakdown at the edge of the junction is better restrained.
Further, the buffer layer is an n+ type InP layer, the absorption layer is an i type InGaAs layer, the gradual change layer is an i type InGaAsP layer, the charge layer is an n type InP layer, and the cap layer is an i type InP layer.
Further, the substrate layer is an n+ type InP layer with lower resistance, the passivation layer is silicon dioxide or silicon nitride, the passivation effect on the surface of the cap layer (i.e. the InP layer) is good, and the preparation process is mature.
In addition, the invention also provides a preparation method of the near infrared single photon array detector, which specifically comprises the following steps:
step 1, sequentially growing an epitaxial layer on the upper surface of a prepared substrate layer, wherein the epitaxial layer comprises a buffer layer, an absorption layer, a gradual change layer, a charge layer and a cap layer which are sequentially grown from bottom to top;
step 2, growing a passivation layer on the upper surface of the cap layer through an ALD thin film deposition process;
Step 3, fixing the substrate layer and the epitaxial layer on a supporting device, and thinning the lower surface of the substrate layer;
Step 4, after growing an anti-reflection layer on the lower surface of the substrate layer by adopting a PECVD vapor deposition method, stripping and cleaning the substrate layer and the epitaxial layer growing the anti-reflection layer from the supporting device;
step5, photoetching a plurality of second electrode windows and a plurality of third electrode windows which are distributed at intervals on the passivation layer;
Step 6, respectively processing an active diffusion region and a diffusion isolation region with a stepped structure at the outer sides of the second electrode window and the third electrode window, wherein the bottoms of the active diffusion region and the diffusion isolation region are both positioned in the cap layer;
Step 7, washing off the original passivation layer, and growing the passivation layer again on the surface of the cap layer, in the active diffusion region and in the diffusion isolation region;
step 8, preparing a pixel anode metal electrode and an isolation region electrode by adopting an electron beam evaporation process at the inner sides of the second electrode window and the third electrode window respectively;
Step 9, respectively photoetching a first electrode window and a pixel incidence window which are distributed at intervals on the anti-reflection layer;
step 10, etching the first electrode window to the lower surface of the substrate layer by adopting a wet etching process;
and step 11, preparing a pixel cathode metal electrode in the first electrode window, and performing rapid annealing treatment on the pixel cathode metal electrode to obtain the near infrared single photon array detector.
Further, step 6 includes the steps of:
6.1, respectively etching the outer sides of the second electrode window and the third electrode window to the upper surface of the cap layer adjacent to the second electrode window and the third electrode window through a wet etching process;
6.2, etching the upper surface of the cap layer in the step 6.1 through a plasma etching process, wherein the etching depth is 0.5-2.0 mu m;
6.3, rapidly processing the etching area in the step 6.2 by adopting a wet etching process, thereby reducing the surface roughness;
And 6.4, processing an active diffusion region and a diffusion isolation region with step structures between the outer sides of the second electrode window and the third electrode window and the cap layer respectively through a closed-tube Zn diffusion process.
In step 7, the original passivation layer is washed away by adopting HF solution to prevent the passivation layer from being polluted during Zn diffusion, so that the passivation effect is poor, and the passivation layer grows again on the surface of the cap layer, in the active diffusion region and in the diffusion isolation region by adopting ALD thin film deposition technology.
Compared with the prior art, the invention has the following beneficial effects:
1. The near infrared single photon array detector comprises a passivation layer, a plurality of second electrode windows and a plurality of third electrode windows, wherein the passivation layer is uniformly distributed with a plurality of second electrode windows and a plurality of third electrode windows at intervals, a pixel anode metal electrode is arranged at the inner side of each second electrode window, an isolation region electrode is arranged at the inner side of each third electrode window, an active diffusion region is formed at the outer sides of a cap layer and the second electrode windows, a diffusion isolation region is formed between the cap layer and the third electrode windows in a surrounding mode, the diffusion isolation region is of a step structure, the depth of the diffusion isolation region is the same as that of the active diffusion region, on one hand, transverse diffusion carriers at the deeper position of a multiplication layer can be isolated, on the other hand, electric field distribution at the edge of a center junction can be optimized, edge breakdown of a device can be well restrained, and further isolation effect is improved.
2. According to the preparation method of the detector, the stepped active diffusion region is formed through the one-step Zn diffusion process, so that the edge breakdown probability of the active diffusion region is effectively reduced, and the effective detection of the near infrared band weak light signals can be realized in the geiger mode.
3. According to the preparation method of the detector, pits are formed in the diffusion isolation region in advance through wet etching and plasma etching, and the isolation depth of the diffusion isolation region in the InP cap layer is increased by combining a Zn diffusion process, so that the electric crosstalk between pixels is reduced.
4. According to the preparation method of the detector, the passivation layer grows on the side wall of the etching area through the ALD thin film deposition process, so that the problem of poor coverage of the side wall thin film in the traditional vapor deposition process is solved, and the surface passivation effect of the etching area is improved.
5. The preparation method of the detector realizes the preparation of the pixel structure with good crosstalk characteristic and edge breakdown characteristic through one-time Zn diffusion process, has low process difficulty, and can be applied to the preparation of a large-scale InGaAs avalanche diode array in the future.
Drawings
FIG. 1 is a schematic diagram of a near infrared single photon array detector according to an embodiment of the invention.
The reference numerals are as follows:
1-antireflection layer, 11-pixel incidence window, 12-first electrode window, 2-substrate layer, 3-epitaxial layer, 31-buffer layer, 32-absorption layer, 33-graded layer, 34-charge layer, 35-cap layer, 36-active diffusion region, 37-diffusion isolation region, 4-passivation layer, 41-second electrode window, 42-pixel anode metal electrode, 43-third electrode window, 44-isolation region electrode.
Detailed Description
The invention provides a back-illuminated planar single-photon detector array with a step-shaped isolation region and a manufacturing method based on a single Zn diffusion process, which can achieve the purposes of ① adopting a mode of combining pre-thinning (namely adopting wet etching and plasma etching in sequence) and a single Zn diffusion process, adopting a simpler manufacturing process to form a step-shaped P-type doped region, and reducing the process difficulty. ② The novel deep doped isolation structure is designed, the preparation of an isolation region can be completed by adopting a mode of combining pre-thinning and one-time Zn diffusion process, and the crosstalk prevention capability of the device is improved.
The invention will be described in further detail below with reference to the accompanying drawings, it being understood that the examples described herein are for illustration only and are not limiting of the invention.
As shown in fig. 1, the invention provides a near infrared single photon array detector, which comprises a substrate layer 2, an epitaxial layer 3 arranged on the upper surface of the substrate layer 2 and an anti-reflection layer 1 arranged on the lower surface of the substrate layer 2, wherein the substrate layer 2 is an n+ type InP layer. The antireflection layer 1 is provided with a plurality of pixel incidence windows 11 and a plurality of first electrode windows 12 which are distributed at intervals, the bottoms of the plurality of first electrode windows 12 are contacted with the lower surface of the substrate layer 2, and pixel cathode metal electrodes are arranged in the first electrode windows 12.
In this embodiment, the epitaxial layer 3 includes a buffer layer 31, an absorption layer 32, a graded layer 33, a charge layer 34 and a cap layer 35 which are sequentially grown from bottom to top, wherein the buffer layer 31 is an n+ type InP layer, the absorption layer 32 is an i type InGaAs layer with a thickness of 1 μm to 2 μm, the graded layer 33 is an i type InGaAsP layer, the charge layer 34 is an n type InP layer with a thickness of 200nm, and the cap layer 35 is an i type InP layer with a thickness of 3.0 μm. The buffer layer 31 is close to the substrate layer 2, and the passivation layer 4 is arranged on one side of the cap layer 35 away from the charge layer 34, wherein the passivation layer 4 is a silicon dioxide or silicon nitride film.
A plurality of second electrode windows 41 and a plurality of third electrode windows 43 are uniformly distributed on the passivation layer 4 at intervals, a pixel anode metal electrode 42 is arranged on the inner side of each second electrode window 41, and an isolation region electrode 44 is arranged on the inner side of each third electrode window 43. The depths of the second electrode window 41 and the third electrode window 43 are the same, the bottoms of the second electrode window 41 and the third electrode window 43 are both positioned in the cap layer 35, the active diffusion region 36 is surrounded by the cap layer 35 and the outer side of the second electrode window 41, and the diffusion isolation region 37 is surrounded by the cap layer 35 and the third electrode window 43.
In this embodiment, all of the diffusion isolation regions 37 are of a step structure, and the depth thereof is the same as that of the active diffusion region 36. The diffusion isolation region 37 includes a shallow isolation region and a deep isolation region disposed from top to bottom, and the width of the shallow isolation region is greater than the width of the deep isolation region. All of the active diffusion regions 36 are also of a stepped structure, including shallow diffusion regions and deep diffusion regions disposed from top to bottom, and the width of the shallow diffusion regions is greater than the width of the deep diffusion regions. The curvature radius of the active diffusion region and the diffusion isolation region is increased through the wider shallow diffusion region and the shallow isolation region, the advanced breakdown at the junction edge is better restrained, and the electric crosstalk between pixels is further restrained.
The key point of the invention is to design a back irradiation InGaAs/InP near infrared single photon array detector, and the array adopts a deep diffusion isolation structure. Compared with the isolation region structure on the traditional planar array, the isolation structure adopted by the array is characterized in that the planar array is etched and thinned in advance, and then P-type doping is carried out. On the basis of not increasing the process difficulty, the isolation depth of the isolation area is effectively increased, and the crosstalk prevention effect is improved.
In addition, the invention also provides a preparation method of the near infrared single photon array detector, which specifically comprises the following steps:
step 1, sequentially growing an epitaxial layer 3 on the upper surface of a prepared InP substrate layer 2 by adopting a PECVD vapor deposition method, wherein the epitaxial layer 3 comprises an InP buffer layer 31, an InGaAs absorption layer 32, an InGaAsP graded layer 33, an InP charge layer 34 and an InP cap layer 35 which are sequentially grown from bottom to top;
step 2, growing an InP cap layer 35 with a thickness of ALD thin film deposition process on the upper surface Is a SiO 2 passivation layer 4;
and 3, fixing the InP substrate layer 2 and the epitaxial layer 3 on a supporting device through bonding, and thinning the lower surface of the substrate layer 2 by 200 mu m by using a chemical mechanical polishing method.
And 4, after growing a 200-300 nm silicon nitride anti-reflection layer 1 on the lower surface of the substrate layer 2 by adopting a PECVD vapor deposition method, stripping the InP substrate layer 2 and the epitaxial layer 3 growing the anti-reflection layer 1 from the supporting device, and carrying out ultrasonic cleaning by using ethanol, acetone and deionized water.
And 5, photoetching a plurality of second electrode windows 41 and a plurality of third electrode windows 43 which are distributed at intervals on the passivation layer 4, wherein the second electrode windows 41 are annular windows with the diameters of 25-35 mu m, and the third electrode windows 43 are strip windows with the widths of 2-3 mu m.
Step 6, processing the active diffusion region 36 and the diffusion isolation region 37 with step structures outside the second electrode window 41 and the third electrode window 43 respectively, specifically:
6.1, respectively etching the outer sides of the second electrode window 41 and the third electrode window 43 to the upper surface of the InP cap layer 35 adjacent to the outer sides by a wet etching process;
6.2, etching the upper surface of the InP cap layer 35 in the step 6.1 by a plasma etching process, wherein the etching depth is 0.5-2.0 mu m;
6.3, rapidly processing the etching area in the step 6.2 by adopting a wet etching process, thereby reducing the surface roughness and defects;
6.4, processing an active diffusion region 36 and a diffusion isolation region 37 with step structures between the outer sides of the second electrode window 41 and the third electrode window 43 and the cap layer 35 respectively through a closed tube type Zn diffusion process, wherein the bottoms of the active diffusion region 36 and the diffusion isolation region 37 are positioned in the InP cap layer 35.
And 7, removing the original passivation layer 4 by adopting an HF solution, and regrowing the passivation layer 4 on the surface of the InP cap layer 35, in the active diffusion region 36 and in the diffusion isolation region 37 by utilizing an ALD process, wherein the thickness of the passivation layer is 200-300 nm.
And 8, preparing a pixel anode metal electrode 42 and an isolation region electrode 44 by adopting an electron beam evaporation process at the inner sides of the second electrode window 41 and the third electrode window 43 respectively.
And 9, respectively photoetching pixel incidence windows 11 and first electrode windows 12 which are distributed at intervals on the anti-reflection layer 1, wherein the pixel incidence windows 11 are annular windows with diameters of 50-55 mu m, and the first electrode windows 12 are of strip structures with widths of 2-3 mu m.
Step 10, etching the first electrode window 12 to the lower surface of the substrate layer 2 by adopting a wet etching process;
And step 11, preparing a pixel cathode metal electrode in the first electrode window 12 through an electron beam evaporation process, and performing rapid annealing treatment on the pixel cathode metal electrode to ensure that the pixel cathode metal electrode and the semiconductor material directly form good ohmic contact, thereby completing the preparation of the near infrared single photon array detector.
In addition, compared with the traditional twice Zn diffusion process, the preparation method of the invention performs pre-corrosion (namely wet corrosion and plasma etching) on the doped region, and then forms a step type P-type doped structure on the InP cap layer 35 after single Zn diffusion, and simultaneously forms a deep diffusion isolation region structure, thereby reducing the process difficulty. In order to solve the problem that the film on the side of the corrosion area is not thoroughly covered, an ALD process is adopted for passivation layer growth, and the side wall passivation effect is improved.
When the near infrared single photon array detector provided by the invention works, the photoelectric avalanche diode array applies reverse bias voltage, photon-generated carriers collide and ionize in the multiplier to cause avalanche, the carriers are amplified and reversely breakdown (Geiger mode) of the APD, and at the moment, the avalanche effect can be caused by the carriers excited by a single photon to generate a measurable signal. Through the pre-etching of the characteristic region, an active diffusion region with a step structure is formed on the InP cap layer through one-time Zn diffusion process treatment, the edge breakdown voltage is reduced, meanwhile, the length of the isolation region is increased, the electric crosstalk between pixels is restrained, further, the parameter optimization of the dark count rate and the imaging resolution of the device is realized, and the preparation process is simple and reliable and can be applied to the subsequent preparation of large-scale arrays.

Claims (6)

1. The preparation method of the near infrared single photon array detector is characterized by comprising the following steps of:
Step 1, sequentially growing an epitaxial layer (3) on the upper surface of a prepared substrate layer (2), wherein the epitaxial layer (3) comprises a buffer layer (31), an absorption layer (32), a gradual change layer (33), a charge layer (34) and a cap layer (35) which are sequentially grown from bottom to top;
step 2, growing a passivation layer (4) on the upper surface of the cap layer (35) through an ALD thin film deposition process;
Step 3, fixing the substrate layer (2) and the epitaxial layer (3) on a supporting device, and thinning the lower surface of the substrate layer (2);
step 4, after growing the anti-reflection layer (1) on the lower surface of the substrate layer (2) by adopting a PECVD vapor deposition method, stripping and cleaning the substrate layer (2) and the epitaxial layer (3) on which the anti-reflection layer (1) is grown from the supporting device;
Step 5, photoetching a plurality of second electrode windows (41) and a plurality of third electrode windows (43) which are distributed at intervals on the passivation layer (4);
step 6, respectively processing an active diffusion region (36) with a step structure and a diffusion isolation region (37) with a step structure at the outer sides of the second electrode window (41) and the third electrode window (43), wherein the bottoms of the active diffusion region (36) and the diffusion isolation region (37) are both positioned in the cap layer (35), and the method specifically comprises the following steps:
6.1, respectively etching the outer sides of the second electrode window (41) and the third electrode window (43) to the upper surface of the cap layer (35) adjacent to the second electrode window through a wet etching process;
6.2, etching the upper surface of the cap layer (35) in the step 6.1 through a plasma etching process, wherein the etching depth is 0.5-2.0 mu m;
6.3, rapidly processing the etching area in the step 6.2 by adopting a wet etching process, thereby reducing the surface roughness;
6.4, processing an active diffusion region (36) and a diffusion isolation region (37) with step structures between the outer sides of the second electrode window (41) and the third electrode window (43) and the cap layer (35) respectively through a closed-tube Zn diffusion process;
step 7, washing off the original passivation layer (4), and regrowing the passivation layer (4) on the surface of the cap layer (35), in the active diffusion region (36) and the diffusion isolation region (37);
Step 8, preparing a pixel anode metal electrode (42) and an isolation region electrode (44) by adopting an electron beam evaporation process at the inner sides of the second electrode window (41) and the third electrode window (43) respectively;
Step 9, respectively photoetching first electrode windows (12) and pixel incidence windows (11) which are distributed at intervals on the anti-reflection layer (1);
Step 10, adopting a wet etching process to etch the first electrode window (12) to the lower surface of the substrate layer (2);
And 11, preparing a pixel cathode metal electrode in the first electrode window (12), and performing rapid annealing treatment on the pixel cathode metal electrode to obtain the near infrared single photon array detector.
2. The method for manufacturing a near infrared single photon array detector according to claim 1, wherein:
In the step 7, the original passivation layer (4) is washed off by adopting an HF solution, and the passivation layer (4) is grown again on the surface of the cap layer (35), in the active diffusion region (36) and in the diffusion isolation region (37) by adopting an ALD thin film deposition process.
3. A near infrared single photon array detector manufactured by the manufacturing method of the near infrared single photon array detector according to claim 1 or 2, characterized in that:
The anti-reflection layer (1) is provided with a plurality of pixel incidence windows (11) and a plurality of first electrode windows (12) which are distributed at intervals, wherein the bottoms of the plurality of first electrode windows (12) are in contact with the lower surface of the substrate layer (2), and pixel cathode metal electrodes are arranged in the first electrode windows (12);
The epitaxial layer (3) comprises a buffer layer (31), an absorption layer (32), a gradual change layer (33), a charge layer (34) and a cap layer (35) which are sequentially grown from bottom to top, wherein the buffer layer (31) is close to the substrate layer (2), and a passivation layer (4) is arranged on one side of the cap layer (35) far away from the charge layer (34);
A plurality of second electrode windows (41) and a plurality of third electrode windows (43) are uniformly distributed on the passivation layer (4) at intervals, a pixel anode metal electrode (42) is arranged on the inner side of each second electrode window (41), and an isolation region electrode (44) is arranged on the inner side of each third electrode window (43);
the depths of the second electrode window (41) and the third electrode window (43) are the same, and the bottoms of the second electrode window and the third electrode window are both positioned in the cap layer (35), the active diffusion region (36) is surrounded by the cap layer (35) and the outer side of the second electrode window (41), and the diffusion isolation region (37) is surrounded by the cap layer and the third electrode window (43);
The diffusion isolation region (37) is of a step structure formed through a one-time Zn diffusion process, the depth of the diffusion isolation region is the same as that of the active diffusion region (36), the diffusion isolation region (37) comprises a shallow isolation region and a deep isolation region which are arranged from top to bottom, and the width of the shallow isolation region is larger than that of the deep isolation region.
4. The near infrared single photon array detector of claim 3, wherein:
the active diffusion region (36) is of a step structure and comprises a shallow diffusion region and a deep diffusion region which are arranged from top to bottom, and the width of the shallow diffusion region is larger than that of the deep diffusion region.
5. The near infrared single photon array detector of claim 4, wherein:
the buffer layer (31) is an n+ type InP layer;
the absorption layer (32) is an i-type InGaAs layer;
The gradual change layer (33) is an i-type InGaAsP layer;
the charge layer (34) is an n-type InP layer;
the cap layer (35) is an i-type InP layer.
6. The near infrared single photon array detector of claim 5, wherein:
The substrate layer (2) is an n+ type InP layer;
the passivation layer (4) is silicon dioxide or silicon nitride.
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