CN117276370A - Silicon drift detector and preparation method thereof - Google Patents
Silicon drift detector and preparation method thereof Download PDFInfo
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- CN117276370A CN117276370A CN202210661871.2A CN202210661871A CN117276370A CN 117276370 A CN117276370 A CN 117276370A CN 202210661871 A CN202210661871 A CN 202210661871A CN 117276370 A CN117276370 A CN 117276370A
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 83
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 83
- 239000010703 silicon Substances 0.000 title claims abstract description 83
- 238000002360 preparation method Methods 0.000 title abstract description 12
- 239000000758 substrate Substances 0.000 claims abstract description 77
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- 229910052751 metal Inorganic materials 0.000 claims description 53
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- 238000001514 detection method Methods 0.000 abstract description 8
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- 230000003647 oxidation Effects 0.000 description 11
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- 238000005516 engineering process Methods 0.000 description 5
- 238000001312 dry etching Methods 0.000 description 4
- 238000011065 in-situ storage Methods 0.000 description 4
- 238000005468 ion implantation Methods 0.000 description 4
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 238000005229 chemical vapour deposition Methods 0.000 description 3
- 238000001259 photo etching Methods 0.000 description 3
- XEEYBQQBJWHFJM-BJUDXGSMSA-N Iron-55 Chemical compound [55Fe] XEEYBQQBJWHFJM-BJUDXGSMSA-N 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
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- 238000010586 diagram Methods 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 238000000206 photolithography Methods 0.000 description 2
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- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 238000009827 uniform distribution Methods 0.000 description 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
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- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
- H01L31/115—Devices sensitive to very short wavelength, e.g. X-rays, gamma-rays or corpuscular radiation
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Abstract
The invention provides a silicon drift detector and a preparation method thereof, belongs to the technical field of high-energy ray detection devices, and solves the problem that the performance of the silicon drift detector is affected by the charge of an oxide layer between drift rings and the preparation method of the detector in the existing silicon drift detector; the anode doping region is positioned in the central region of the surface of the substrate, the drift region is a continuous region which surrounds the periphery of the anode doping region and extends in the direction away from the anode doping region, and the thickness of the drift region gradually decreases in the direction away from the anode doping region. The drift region of the silicon drift detector is a continuous region, so that the existence of an oxide film is avoided, the silicon drift detector has good detection performance and energy resolution, and the preparation method is simple.
Description
Technical Field
The invention belongs to the technical field of high-energy ray detection devices, and relates to a silicon drift detector and a preparation method thereof.
Background
The silicon drift detector is a silicon-based detector mainly used for detecting high-energy rays, and since the years of the proposal by Gatti and Rehak in 1984, the detector has been widely studied, and the device performance has been greatly improved. The silicon drift detector is a device which adopts lateral depletion, and the substrate of the detector is in a fully depleted state in actual operation, and electrons generated by high-energy rays drift to an anode transversely along a direction parallel to the surface of the device and are collected. The greatest advantage of such a detector is that the device capacitance is very small and does not increase with the increase of the device area, since the device capacitance is relatively small, the detector has a very high energy resolution and count rate.
In order to generate a lateral drift electric field in a silicon drift detector (as shown in fig. 2), it is common practice to prepare a series of drift electrodes on the surface of the detector, which are essentially PN junctions prepared on a substrate, and a typical silicon drift detector structure is shown in fig. 1, with a large number of concentric rings around the electron collector (anode), these being the drift rings. And voltage dividers (resistors) are designed between the drift rings, and when certain voltages are respectively applied to the outermost ring and the innermost ring of the drift rings, the voltage dividers enable the voltage differences to fall on the drift rings uniformly, so that a transverse drift electric field is formed. The signal electrons will be collected to the anode driven by the drift electric field. In this structure, the drift ring gap is a silicon substrate covered with a silicon oxide film. The oxide layer film has a certain positive charge, so that an electron potential well is easily formed on the surface of the silicon substrate, on one hand, signal electrons are lost, and the detection performance of the device is affected; on the other hand, the charge in these potential wells can cause increased device noise and also degrade device energy resolution.
In order to solve the influence caused by the charge of the oxide layer, researchers design a river structure on the surface of the silicon drift detector for guiding the induced charge under the oxide layer. But this design clearly greatly increases the processing difficulty of the device.
Disclosure of Invention
In view of the above analysis, the present invention aims to provide a silicon drift detector and a method for manufacturing the same, which solve the problem that the oxide layer between drift rings and the method for manufacturing the detector in the silicon drift detector in the prior art affect the performance of the silicon drift detector.
The aim of the invention is mainly realized by the following technical scheme:
in one aspect, the invention provides a silicon drift detector comprising a substrate, an anode doped region arranged on one side of the substrate, a drift region, and an incident surface doped region arranged on the other side of the substrate;
the anode doping region is located in a central region of the surface of the substrate, the drift region is a continuous region which surrounds the periphery of the anode doping region and extends in a direction away from the anode doping region, and the thickness of the drift region gradually decreases in a direction away from the anode doping region.
Preferably, the thickness of the drift region is gradually reduced in a stepwise manner in a direction away from the anode doped region.
Preferably, a ground ring is arranged at the edge of one surface of the substrate provided with the drift region, and a plurality of anode surface protection rings which are uniformly arranged at intervals are arranged between the edge of the drift region far away from the anode doping region and the ground ring.
Preferably, the incident surface doping region extends to a position corresponding to the side of the drift region away from the anode doping region along the direction away from the center of the surface of the substrate, and the incident surface protection ring corresponding to the anode surface protection ring is further arranged on the surface of the substrate provided with the incident surface doping region.
Preferably, gaps are arranged between the edge of the drift region, which is close to the anode doping region, and the anode doping region, between the edge of the drift region, which is far away from the anode doping region, and the anode surface protection ring closest to the drift region, and between the grounding ring and the anode surface protection ring closest to the grounding ring.
Preferably, an insulating medium layer is arranged on the surface of the substrate between the edge of the drift region close to the anode doping region and the anode doping region, between the edge of the drift region far away from the anode doping region and the anode surface protection ring closest to the drift region, between the grounding ring and the anode surface protection ring closest to the grounding ring, between the anode surface protection ring and the anode surface protection ring, and between the incident surface protection ring and the incident surface protection ring.
Preferably, the doping type of the drift region is opposite to the doping type of the substrate, and the doping types of the anode surface protection ring, the incident surface protection ring and the incident surface doping region are the same as the doping type of the drift region.
Preferably, the doping type of the anode doping region and the grounding ring is the same as the doping type of the substrate.
Preferably, the upper surface of the anode doped region is provided with an anode metal electrode, the upper surface of the drift region, which is close to the edge region of the anode doped region, is provided with a drift region inner side metal electrode, the upper surface of the drift region, which is far away from the edge region of the anode doped region, is provided with a drift region outer side metal electrode, the upper surface of the grounding ring is provided with a grounding ring metal electrode, and the upper surface of the edge region of the incident surface doped region is provided with an incident surface metal electrode.
On the other hand, the invention also provides a preparation method of the silicon drift detector, wherein the silicon drift detector is the silicon drift detector of the invention, and the preparation method comprises the following steps:
forming an anode doped region on a substrate;
growing a silicon film on a substrate, and etching the silicon film to gradually reduce the thickness of the drift region along the direction away from the anode doping region so as to form a drift region;
forming an incident surface doping region, a grounding ring, an anode surface protection ring and an incident surface protection ring on a substrate;
and forming an anode metal electrode on the anode doping region, forming a drift region inner side metal electrode on the drift region close to the anode doping region, forming a drift region outer side metal electrode on the drift region far away from the anode doping region, forming a grounding ring metal electrode on the grounding ring, and forming an incident surface metal electrode on the incident surface doping region.
Compared with the prior art, the invention has at least one of the following beneficial effects:
1. the drift region of the silicon drift detector is a continuous region, so that the existence of an oxidation film of the drift region is avoided, an electron potential well does not exist on the surface of a substrate of the drift region, the leakage noise of a device is reduced, the energy resolution of the detector is improved, signal electron loss does not exist, and the detection performance of the device is improved.
2. In the invention, the thickness of the drift region is gradually reduced along the direction away from the anode doped region, so that the uniform distribution of the resistance of the drift region from the anode doped region to the direction away from the anode doped region is realized, and a drift electric field is further formed.
3. The drift region of the silicon drift detector is simple in structure and simple in preparation method, can be formed by combining traditional film growth with etching or photoetching steps, and cannot influence the performance of the drift region in the preparation process.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, like reference numerals being used to refer to like parts throughout the several views.
FIG. 1 is a schematic diagram of a conventional silicon drift detector;
FIG. 2 is a schematic diagram of a lateral drift electric field in a silicon drift detector;
FIG. 3 is a top view of a silicon drift detector of the present invention;
FIG. 4 is a cross-sectional view of a silicon drift detector of the present invention from the center of the anode to the edge of the detector;
fig. 5 is a cross-sectional view of a silicon drift detector from the center of the anode to the edge of the detector, as implemented by an etching process.
Fig. 6 is a graph showing detection performance of the silicon drift detector according to embodiment 1 of the present invention.
Reference numerals:
1-a substrate; 2-an anode doped region; a 3-drift region; 4-an incident surface doping region; a 5-ground ring; 6-anode surface guard ring; 7-an incident face guard ring; 8-an anode metal electrode; the method comprises the steps of carrying out a first treatment on the surface of the 9-a metal electrode on the inner side of the drift region; 10-a metal electrode outside the drift region; 11-a grounding ring metal electrode; 12-incidence face metal electrode; 13-collecting anodes; a 14-drift ring region; 15-a back electrode; r-radius of the circle where the arbitrary point A is located; h-thickness of drift region where arbitrary point a is located.
Detailed Description
Preferred embodiments of the present invention are described in detail below with reference to the attached drawing figures, which form a part of the present invention and are used in conjunction with the embodiments of the present invention to illustrate the principles of the present invention.
In one aspect, the present invention provides a silicon drift detector, as shown in fig. 3-4, the silicon drift detector includes a substrate 1, an anode doped region 2 disposed on one surface of the substrate 1, a drift region 3, and an incident surface doped region 4 disposed on the other surface of the substrate 1;
wherein the anode doped region 2 is located in a central region of the surface of the substrate 1, the drift region 3 is a continuous region extending around the periphery of the anode doped region 2 in a direction away from the anode doped region 2, and the thickness of the drift region 3 gradually decreases in a direction away from the anode doped region 2.
When the silicon drift detector works, the maximum reverse bias voltage (at least twice the depletion voltage of the substrate) is applied to one side of the drift region far away from the anode doping region, the minimum reverse bias voltage is applied to one side of the drift region close to the anode doping region, and the two voltage differences uniformly distribute the resistance of the drift region per se in the whole drift region to form a drift electric field.
Compared with the prior art, the drift region of the silicon drift detector is a continuous region, has a simple structure, avoids the existence of an oxidation film of the drift region, does not have an electron potential well on the surface of a substrate of the drift region, is beneficial to reducing the leakage noise of a device, improves the energy resolution of the detector, does not have signal electron loss, enhances the collection of carriers and improves the detection performance of the device; in the invention, the thickness of the drift region is gradually reduced along the direction away from the anode doped region, the longer the circumference of the concentric ring taking the anode doped region as the center is, the smaller the thickness of the drift region is, so that the expanded areas of the concentric rings taking the anode doped region as the center in the drift region are equal.
Specifically, the concentric ring is rectangular after being unfolded, the circumference of the circle is rectangular long, the thickness of the drift region is rectangular wide, the circumference of the circle is longer and longer along the direction away from the anode doping region, and the thickness of the drift region is smaller and smaller, so that the product of the length and the width of the rectangle can be a fixed value, that is, the rectangular area formed by the unfolded concentric ring is equal, that is, as shown in fig. 3 and fig. 4, the product of the circumference C (c=2pi r) of the circle where any point a in the drift region is located and the thickness h of the drift region where the point a is located is a fixed value, and the resistance of the drift region from the anode doping region to the direction away from the anode doping region is uniformly distributed, so that a drift electric field is formed.
In the invention, considering that the realization of different thicknesses of the drift region is realized through an etching process, and the etching process can only realize plane etching, the upper surface of the drift region can inevitably form steps when the drift region with gradually reduced thickness is prepared through the etching process, so that the thickness of the drift region 3 gradually reduces in a step shape along the direction away from the anode doped region 2.
In order to achieve as uniform a distribution of the resistances as possible, the steps should be as small as possible, as shown in fig. 5. In fig. 5, the resistance uniform distribution is satisfied at the edge of each step.
In the invention, a grounding ring 5 is arranged at the edge of the substrate 1, and a plurality of anode surface protection rings 6 are arranged between the edge of the drift region 3 away from the anode doping region 2 and the grounding ring 5 at uniform intervals. The number of anode face guard rings 6 may be a conventional choice in the art, for example, the number of anode face guard rings 6 may be 5. The anode surface guard ring 6 is used for increasing breakdown voltage, and the ground ring 5 is used for collecting leakage noise outside the drift region 3.
In the present invention, the incident surface doped region 4 extends along the center of the surface of the substrate 1 in a direction away from the center to a position corresponding to a side of the drift region 3 away from the anode doped region 2, and the surface of the substrate 1 provided with the incident surface doped region 4 is further provided with an incident surface guard ring 7 corresponding to the anode surface guard ring 6. That is, the incident surface doping region 4 covers a region from the center of the substrate 1 to a position corresponding to the side of the drift region 3 away from the anode doping region 2. The incidence surface doping region 4 is a thin film technology, namely, a layer of thin film is independently arranged on the other surface of the substrate 1 to serve as the incidence surface doping region 4, instead of the existing method of directly carrying out ion implantation doping or diffusion doping into the substrate 1, the incidence surface doping region 4 can form passivation contact effect, the surface state density of the substrate 1 is reduced, and leakage noise is reduced.
In the drawings of the present invention, the substrate 1 is circular, and correspondingly, the anode doped region 2 and the incident surface doped region 4 are circular, and the drift region 3, the anode surface guard ring 6, the incident surface guard ring 7 and the ground ring 5 are concentric circles. The substrate 1 may also have other shapes, such as regular hexagons, regular quadrilaterals, etc., and the respective areas on the substrate 1 are also arranged in corresponding shapes.
In the present invention, in order to achieve isolation between the regions on the substrate 1, it is preferable that a gap is provided between the drift region 3 and the anode doping region 2, between the drift region 3 and the anode protection ring 6 nearest to the drift region 3, and between the ground ring 5 and the anode protection ring 6 nearest to the ground ring 5. A gap is provided between the incidence surface doped region 4 and the incidence surface guard ring 7 nearest to the incidence surface doped region 4.
Further, insulating dielectric layers are provided between the drift region 3 and the anode doped region 2, between the drift region 3 and an anode surface guard ring 6 nearest to the drift region 3, between the ground ring 5 and the anode surface guard ring 6 nearest to the ground ring 5, between the anode surface guard ring 6 and the anode surface guard ring 6, and between the incident surface guard ring 7 and the incident surface guard ring 7 on the surface of the substrate 1. In addition, an insulating dielectric layer is disposed on the surface of the substrate 1 between the incidence surface doped region 4 and the incidence surface guard ring 7 nearest to the incidence surface doped region 4. That is, the exposed surface of the substrate 1 is provided with an insulating dielectric layer for isolating the respective regions from the rings.
In the invention, the insulating medium layer comprises one or more of silicon oxide, silicon nitride or aluminum oxide.
It is worth mentioning that the existing silicon drift detector adopts a thermal oxidation process to form a thicker silicon oxide film on the surface of the silicon substrate, the oxidation temperature is high (about 1000 ℃) and the oxidation time is long (about 10 hours), the quality of the silicon substrate is easily degraded, and the energy resolution of the silicon drift detector is affected; in addition, the silicon oxide film can generate a large amount of positive charges under the irradiation of high-energy particles, and the surface electric field of the silicon drift surface electric field is influenced, so that the performance of the silicon drift detector is poor.
Although the surface of the silicon drift detector is also provided with the oxide film (insulating medium layer), the oxide film (the drift region has no oxide film) has smaller area compared with the prior art, so the requirement on the oxide film is low, chemical oxidation growth and PECVD growth can be adopted to replace the existing thermal oxidation process growth, and the influence of thermal oxidation on the performance of the silicon drift detector is avoided; in addition, the oxide film has small area, so that the oxide film has small influence on the performance of the silicon drift detector.
According to a preferred embodiment of the invention, the doping type of the drift region 3 is opposite to the doping type of the substrate 1, and the doping type of the anode surface guard ring 6, the doping type of the entrance surface guard ring 7 and the doping type of the entrance surface doped region 4 are the same as the doping type of the drift region 3. The drift region 3, the anode guard ring 6, and the incident surface guard ring 7 are formed of PN junctions. Further, the doping type of the anode doping region 2 and the ground ring 5 is the same as the doping type of the substrate 1.
Specifically, the substrate 1 of the silicon drift detector is an N-type lightly doped silicon substrate, wherein the dopant is P or As, and other five-group elements; correspondingly, the drift region 3, the anode surface protection ring 6, the incident surface protection ring 7 and the incident surface doping region 4 are heavily doped with P+ type, and the anode doping region 2 and the grounding ring 5 are heavily doped with N+ type. In other embodiments, the substrate 1 of the silicon drift detector may be a P-type lightly doped silicon substrate, and correspondingly, the drift region 3, the anode surface guard ring 6, the incident surface guard ring 7 and the incident surface doped region 4 are heavily doped with n+ type, and the anode doped region 2 and the ground ring 5 are heavily doped with p+ type. However, when the substrate 1 is a P-type lightly doped silicon substrate, the drifting carriers are holes and the corresponding drifting rate is reduced, so that an N-type lightly doped silicon substrate is preferably used in view of the drifting rate and the like.
In the invention, the doping concentration of the N type light doping is 1e11-1e12, the doping concentration of the N+ type heavy doping is 1e19-1e21, and the doping concentration of the P+ type heavy doping is 1e19-1e21. The main purpose is the PN junction formed, and the depletion region is to fall into the substrate.
In the invention, an anode metal electrode 8 is arranged on the anode doped region 2, a drift region inner metal electrode 9 is arranged on the drift region 3 near the anode doped region 2, a drift region outer metal electrode 10 is arranged on the drift region 3 far away from the anode doped region 2, a grounding ring metal electrode 11 is arranged on the grounding ring 5, and an incident surface metal electrode 12 is arranged on the incident surface doped region 4. The anode surface guard ring 6 and the incident surface guard ring 7 may be provided with metal electrodes or may not be provided with metal electrodes.
In the invention, the anode metal electrode 8, the grounding ring metal electrode 11 and the incidence surface metal electrode 12 are used for forming ohmic contact and can be common metal materials such as gold, silver or aluminum; the drift region inner side metal electrode 9 and the drift region outer side metal electrode 10 are used for applying external bias voltage, and gold, aluminum or silver can be adopted;
in another aspect, the present invention provides a method for preparing a silicon drift detector, where the silicon drift detector is a silicon drift detector according to the present invention, the method includes:
forming an anode doped region 2 on a substrate 1;
growing a silicon film on a substrate 1, and etching the silicon film so that the thickness of the drift region 3 gradually decreases along the direction away from the anode doping region 2 to form a drift region 3;
forming an incident surface doping region 4, a ground ring 5, an anode surface guard ring 6 and an incident surface guard ring 7 on a substrate 1;
an anode metal electrode 8 is formed on the anode doped region 2, a drift region inner metal electrode 9 is formed on the side of the drift region 3 close to the anode doped region 2, a drift region outer metal electrode 10 is formed on the side of the drift region 3 far from the anode doped region 2, a ground ring metal electrode 11 is formed on the ground ring 5, and an incident surface metal electrode 12 is formed on the side of the incident surface doped region 4.
The silicon drift detector has the advantages that the preparation method is simple, the drift region can be formed by combining the traditional film growth technology with etching or photoetching steps, and the performance of the drift region is not affected in the preparation process.
In forming the anode doped region 2, in one possible embodiment, a CVD process is used to grow a doped silicon film in situ, and dry etching techniques are used to form the anode doped region 2 on the substrate 1.
When the drift region 3 is formed, in one possible implementation manner, a CVD method may be directly used to grow a doped silicon film in situ or ex situ, and then a dry etching technique or a wet etching technique may be used in combination with photolithography to sequentially reduce the thickness of the drift region from inside to outside along the radial direction, and simultaneously, in combination with an ion implantation technique to regulate the doping concentration, so as to realize uniform partial pressure of the drift region. Conversely, the thickness of the drift region from outside to inside along the radial direction can be gradually increased by combining CVD with mask technologies such as photoetching and the like, and the doping concentration in the film can be adjusted by combining an ion implantation process, so that the uniform partial pressure of the drift region can be realized.
In forming the entrance face doped region 4, the ground ring 5, the anode face guard ring 6, and the entrance face guard ring 7 on the substrate 1, in one possible implementation, the entrance face doped region 4, the ground ring 5, the anode face guard ring 6, and the entrance face guard ring 7 are formed on the substrate 1 using a CVD process.
When the anode metal electrode 8, the drift region inner metal electrode 9, the drift region outer metal electrode 10, the ground ring metal electrode 11, and the incident surface metal electrode 12 are formed, the formation of each metal electrode may be achieved by a deposition process.
In addition, a silicon oxide film is formed on the exposed substrate surface by a chemical oxidation+PECVD method.
The CVD, etching, photolithography, deposition, chemical oxidation, PECVD, etc. processes in the above methods may be conventional methods in the art, and are not described herein.
The silicon drift detector and the method for manufacturing the same according to the present invention are further described below by way of specific examples.
Example 1
a. A doped silicon film is grown in situ by a CVD method, and then an anode doped region 2 is formed on the substrate 1 (circular) by a dry etching technique.
b. Adopting a CVD method to grow a doped silicon film in situ, adopting a dry etching technology, combining lithography to sequentially reduce the film thickness of the drift region from inside to outside along the radial direction, and simultaneously combining an ion implantation technology to regulate the doping concentration to form a drift region 3; the substrate 1 is an N-type lightly doped silicon substrate, the drift region 3, the anode surface protection ring 6, the incident surface protection ring 7 and the incident surface doping region 4 are p+ type heavily doped, and the anode doping region 2 and the grounding ring 5 are n+ type heavily doped.
c. An incidence plane doped region 4, a ground ring 5, an anode plane guard ring 6, and an incidence plane guard ring 7 are formed on a substrate 1.
d. An anode metal electrode 8 is deposited on the anode doped region 2, a drift region inner metal electrode 9 is deposited on the side of the drift region 3 close to the anode doped region 2, a drift region outer metal electrode 10 is deposited on the side of the drift region 3 remote from the anode doped region 2, a ground ring metal electrode 11 is deposited on the ground ring 5, and an incident surface metal electrode 12 is deposited on the side of the incident surface doped region 4.
e. And forming a silicon oxide film on the exposed substrate surface by a chemical oxidation and PECVD method.
The detection performance of the silicon drift detector prepared in example 1 was measured by the following specific method: the prepared silicon drift detector and the pre-sensitive amplifier are bound to a PCB, a 55Fe radioactive source is adopted to irradiate the detector, the output end of the pre-sensitive amplifier is linked to an energy spectrum amplifier, and after signals are further amplified, the signals are input to a multi-channel analyzer, so that the energy resolution of the detector can be obtained. The results are shown in FIG. 6. As can be seen in fig. 6, the silicon drift detector of the present invention is effective in detecting X-ray signals from the iron 55 radioactive source. The energy resolution of the silicon drift detector of the present invention was 183eV.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.
Claims (10)
1. A silicon drift detector, characterized in that the silicon drift detector comprises a substrate (1), an anode doping region (2) arranged on one side of the substrate (1), a drift region (3), and an incident surface doping region (4) arranged on the other side of the substrate (1);
the anode doping region (2) is located in a central region of the surface of the substrate (1), the drift region (3) is a continuous region extending around the periphery of the anode doping region (2) in a direction away from the anode doping region (2), and the thickness of the drift region (3) is gradually reduced along the direction away from the anode doping region (2).
2. A silicon drift detector according to claim 1, characterized in that the thickness of the drift region (3) decreases stepwise in a direction away from the anode doped region (2).
3. Silicon drift detector according to claim 1, characterized in that the edge of the side of the substrate (1) where the drift region (3) is provided with a ground ring (5), and that a number of anode surface guard rings (6) are provided between the edge of the drift region (3) remote from the anode doping region (2) and the ground ring (5) at even intervals.
4. A silicon drift detector according to claim 3, characterized in that the entrance face doping region (4) extends to a position corresponding to the edge of the drift region (3) remote from the anode doping region (2) in a direction away from the centre of the surface of the substrate (1), the face of the substrate (1) provided with the entrance face doping region (4) being further provided with an entrance face guard ring (7) corresponding to the anode face guard ring (6).
5. The silicon drift detector according to claim 4, characterized in that a gap is provided between the drift region (3) near the edge of the anode doping region (2) and the anode doping region (2), between the edge of the drift region (3) away from the anode doping region (2) and the anode face guard ring (6) nearest to the drift region (3), between the ground ring (5) and the anode face guard ring (6) nearest to the ground ring (5).
6. The silicon drift detector according to claim 5, characterized in that the surface of the substrate (1) between the edge of the drift region (3) close to the anode doping region (2) and the anode doping region (2), between the edge of the drift region (3) remote from the anode doping region (2) and the anode face guard ring (6) closest to the drift region (3), between the ground ring (5) and the anode face guard ring (6) closest to the ground ring (5), between the anode face guard ring (6) and between the entrance face guard ring (7) and the entrance face guard ring (7) is provided with an insulating medium layer.
7. The silicon drift detector according to claim 4, characterized in that the doping type of the drift region (3) is opposite to the doping type of the substrate (1), the doping type of the anode face guard ring (6), the incident face guard ring (7) and the incident face doping region (4) being the same as the doping type of the drift region (3).
8. The silicon drift detector according to claim 7, characterized in that the doping type of the anode doping region (2) and the ground ring (5) is the same as the doping type of the substrate (1).
9. A silicon drift detector according to claim 3, characterized in that the anode doping region (2) upper surface is provided with an anode metal electrode (8), the drift region (3) is provided with a drift region inner metal electrode (9) close to the anode doping region (2) upper surface, the drift region (3) is provided with a drift region outer metal electrode (10) far away from the anode doping region (2) upper surface, the ground ring (5) upper surface is provided with a ground ring metal electrode (11), and the incident surface doping region (4) upper surface is provided with an incident surface metal electrode (12).
10. A method for manufacturing a silicon drift detector, wherein the silicon drift detector is the silicon drift detector according to claims 1-9, the method comprising:
forming an anode doped region (2) on a substrate (1);
growing a silicon film on a substrate (1), and etching the silicon film so that the thickness of the drift region (3) gradually decreases along the direction away from the anode doping region (2) to form a drift region (3);
forming an incident surface doping region (4), a grounding ring (5), an anode surface protection ring (6) and an incident surface protection ring (7) on a substrate (1);
an anode metal electrode (8) is formed on the anode doping region (2), a drift region inner side metal electrode (9) is formed on the side, close to the anode doping region (2), of the drift region (3), a drift region outer side metal electrode (10) is formed on the side, far away from the anode doping region (2), of the drift region (3), a grounding ring metal electrode (11) is formed on the grounding ring (5), and an incidence surface metal electrode (12) is formed on the side, close to the anode doping region (2), of the drift region (3).
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