阅读说明：本技术 一种多结型锗基长波红外探测器及制备方法 (Multi-junction germanium-based long-wave infrared detector and preparation method thereof ) 是由 潘昌翊 邓惠勇 牟浩 殷子薇 汪越 窦伟 张祎 姚晓梅 戴宁 于 2021-08-13 设计创作，主要内容包括：本发明公开了一种多结型锗基长波红外探测器及制备方法,所述探测器由锗基底、电极区、吸收区、阻挡区、引线电极和钝化层组成,制备方法包括四个步骤,即通过光刻、离子注入、快速退火、薄膜淀积和干法刻蚀等工艺在高阻锗基底上依次形成吸收区、电极区、钝化层和引线电极。本发明制备的长波红外探测器,在传统阻挡杂质带探测器结构的基础上,引入多个吸收区和阻挡区,从而获得多个耗尽区,使得耗尽区宽度增加,器件有效吸光区域增大,探测器的响应率和探测率得到提高。本发明的制备方法与当前的半导体工艺技术相兼容,研发和生产成本低。(The invention discloses a multi-junction germanium-based long-wavelength infrared detector and a preparation method thereof, wherein the detector consists of a germanium substrate, an electrode area, an absorption area, a blocking area, a lead electrode and a passivation layer. According to the long-wave infrared detector prepared by the invention, on the basis of the traditional impurity band blocking detector structure, a plurality of absorption regions and blocking regions are introduced, so that a plurality of depletion regions are obtained, the width of the depletion region is increased, the effective light absorption region of a device is enlarged, and the response rate and the detection rate of the detector are improved. The preparation method is compatible with the current semiconductor process technology, and has low research and development and production cost.)

1. A multijunction type germanium-based long-wave infrared detector comprises a germanium substrate (1), an electrode region (2), an absorption region (3), a blocking region (4), a lead electrode (5) and a passivation layer (6), and is characterized in that:

the long-wave infrared detector adopts a plane structure, namely, the electrode area (2), the absorption area (3) and the blocking area (4) are all positioned in the near surface layer of the germanium substrate (1);

the lead electrode (5) is positioned above the electrode area (2), and the passivation layer (6) is positioned above the absorption area (3) and the blocking area (4);

the absorption region (3) and the blocking region (4) are periodically distributed between the lead electrodes (5);

the long-wave infrared detector is provided with n absorption regions (3) and n blocking regions (4) so as to have n depletion regions, the width of each depletion region is increased by n-1 times, and n is greater than or equal to 2 and less than or equal to 10.

2. The multi-junction germanium-based long-wavelength infrared detector according to claim 1, wherein: the germanium substrate (1) is high-resistance type, and the impurity concentration range is 1 x 10¹²～1×10¹⁴cm^-3。

3. The multi-junction germanium-based long-wavelength infrared detector according to claim 1, wherein: the electrode area (2) is degenerately doped germanium material, the doping element is boron, gallium or beryllium, and the impurity concentration range is 5 multiplied by 10¹⁸～5×10¹⁹cm^-3The doping depth is 0.2-2 μm, and the width is 50-200 μm.

4. The multi-junction germanium-based long-wavelength infrared detector according to claim 1, wherein: the absorption region (3) is doped with germanium material, the doping element is boron, gallium or beryllium, and the concentration range of impurities is 1 x 10¹⁶～1×10¹⁷cm^-3The doping depth is 0.2-2 μm, and the width is 5-50 μm.

5. The multi-junction germanium-based long-wavelength infrared detector according to claim 1, wherein: the blocking region (4) is made of high-resistance germanium material, and the width range is 1-5 mu m.

6. A method of making the multi-junction ge-based long wavelength infrared detector of claim 1, comprising the steps of:

firstly, forming an absorption region pattern on the surface of a germanium substrate (1) by utilizing a photoetching process, and then implanting required impurities into ions to form an absorption region (3);

forming an electrode area pattern on the surface of the germanium substrate (1) by utilizing a photoetching process, and then injecting ions into required impurities to form an electrode area (2);

thirdly, depositing a silicon nitride passivation layer (6) on the surface of the germanium substrate (1) by using a film deposition process, and then performing a rapid annealing process to activate the ion-implanted impurities;

fourthly, an electrode window is arranged on the passivation layer (6) by utilizing a dry etching process, and then a metal film is evaporated to form the lead electrode (5).

Technical Field

The invention relates to a long-wave infrared detector and a preparation method thereof, and the multi-junction germanium-based long-wave infrared detector is particularly suitable for the field of middle and far infrared astronomical detection in the range of 40-200 mu m.

Background

Infrared astronomy is an important branch of the field of astronomy, and the key to developing infrared astronomy is to develop an infrared detector. Common infrared detectors can be made of materials such as mercury cadmium telluride, indium antimonide, indium gallium arsenide and the like, and all of the materials absorb infrared light by utilizing the properties of semiconductor materials, so that the absorbed photon energy needs to be larger than the forbidden band width of the semiconductor materials, and the detectable wavelength is shorter.

The impurity band blocking detector introduces an impurity energy level by doping a semiconductor material, and absorbs infrared light by utilizing the impurity energy level. The response wavelength of the detector is determined by ionization activation energy of impurities in a semiconductor material, generally, the response wavelength of the silicon-based impurity band blocking detector covers 4-50 mu m, and the response wavelength of the germanium-based impurity band blocking detector and the response wavelength of the gallium arsenide-based impurity band blocking detector can be respectively expanded to 200 mu m and 300 mu m. Compared with other infrared detectors, the impurity band blocking detector has the remarkable advantages and becomes a mainstream detector in the field of middle and far infrared astronomy detection.

The conventional impurity band blocking detector has a structural disadvantage thereof, which limits further improvement of the detection performance. According to theoretical analysis, the electric field intensity in the absorption region of the device is not uniformly distributed, but is distributed only in a narrow depletion region, and the electric field intensity in a neutral region outside the depletion region is small. Only photogenerated carriers generated in the depletion region can be effectively separated under the driving of an electric field, and the photogenerated carriers generated in the neutral region can be quickly recombined. Therefore, in order to improve the detection performance of the device, the width of the depletion region should be made as large as possible. The width of the depletion region is mainly determined by the doping concentration, the working voltage and the width of the blocking region, and the widening difficulty is high. With the further development of astronomy, the requirement on astronomical detection technology is continuously increased, the structure of the existing detector must be optimized and improved, and the performance of the detector is improved.

Disclosure of Invention

The invention aims to provide a multi-junction type germanium-based impurity band (MBIB) long-wave infrared detector, and a preparation method for realizing the structure, and solves the technical problem that the depletion region of the traditional impurity band blocking detector is narrow. The structure and the working mode of the novel detector are different from those of a traditional impurity band detector, and the novel detector is characterized in that:

the long-wave infrared detector adopts a planar structure, namely an electrode area, an absorption area and a blocking area are all positioned in a near surface layer of the germanium substrate;

the lead electrode is positioned above the electrode area, and the passivation layer is positioned above the absorption area and the blocking area;

the absorption region and the blocking region are periodically distributed between the lead electrodes;

the long-wave infrared detector has n absorption regions and n blocking regions, so that n depletion regions are provided, and the width of the depletion regions is increased by n-1 times (n is usually greater than or equal to 2 and less than or equal to 10).

The germanium substrate is high-resistance type, and the impurity concentration range is 1 × 10¹²～1×10¹⁴cm^-3。

The electrode region is made of degenerately doped germanium material, the doping element can be boron, gallium or beryllium, and the impurity concentration range is 5 multiplied by 10¹⁸～5×10¹⁹cm^-3The doping depth is 0.2-2 μm, and the width is 50-200 μm.

The absorption region is doped with germanium material, and the doping elements are boron,Gallium or beryllium with an impurity concentration in the range of 1X 10¹⁶～1×10¹⁷cm^-3The doping depth is 0.2-2 μm, and the width is 5-50 μm.

The blocking region is made of high-resistance germanium material and has a width range of 1-5 μm.

A preparation method for realizing the detector comprises the following steps:

firstly, forming an absorption region pattern on the surface of a germanium substrate by utilizing a photoetching process, and then injecting ions into required impurities to form an absorption region;

forming an electrode area pattern on the surface of the germanium substrate by utilizing a photoetching process, and then injecting ions into required impurities to form an electrode area;

thirdly, depositing a silicon nitride passivation layer on the surface of the germanium substrate by using a film deposition process, and then performing a rapid annealing process to activate the ion-implanted impurities;

fourthly, an electrode window is arranged on the passivation layer by utilizing a dry etching process, and then a metal film is evaporated to form the lead electrode.

The invention has the advantages that:

1. the invention inherits the advantages of the traditional impurity band blocking detector, has long detectable wavelength, avoids the defects of the traditional impurity band blocking detector, and has a plurality of depletion regions with large width and good detection performance.

2. The invention has simple structure and low preparation cost, is compatible with the current semiconductor process, and is easy to be popularized to silicon-based and gallium arsenide-based impurity-blocking band detectors.

Drawings

FIG. 1 is an overall block diagram of the detector of the present invention.

Fig. 2 is a structural diagram of a device of embodiment 1 of the present invention.

Fig. 3 is a structural view of a device of embodiment 2 of the present invention.

Fig. 4 is a structural view of a device of embodiment 3 of the present invention.

FIG. 5 is a flow chart of a process for fabricating a detector according to the present invention.

Detailed Description

The invention is further described in the following description of the invention with reference to examples, which are not intended to limit the scope of the invention, but rather are intended to cover all embodiments within the scope of the invention as described in the summary of the invention and the accompanying description. Theoretical analysis shows that compared with the traditional impurity band blocking detector, the device performance of the embodiment 1 of the invention can be improved by 1 time, the device performance of the embodiment 2 of the invention can be improved by 4 times, and the device performance of the embodiment 3 of the invention can be improved by 9 times. The preparation method of the detector is realized by the following steps:

example 1:

selecting a high-resistance Ge substrate 1 with a doping concentration of 1 × 10¹³cm^-3Two absorption region patterns are manufactured on the surface of the Ge substrate 1 by means of an ultraviolet lithography technology, a single absorption region is 50 microns wide, and the thickness of the used photoresist is about 3 microns and can be used as a masking agent in the subsequent ion implantation process;

implanting impurity B into the absorption region 3 by multiple ion implantation processes to a depth of about 1 μm and a doping concentration of about 4 × 10¹⁶cm^-3；

Manufacturing an electrode region pattern on the surface of the Ge substrate 1 by means of an ultraviolet lithography technology, wherein the electrode region width is 100 micrometers;

implanting impurity B into the electrode region 2 again by multiple ion implantation processes to an implantation depth of about 1 μm and a doping concentration of about 3 × 10¹⁸cm^-3；

Depositing a layer of Si with the thickness of 200nm on the surface of the Ge substrate 1 by means of PECVD technology₃N₄As a device passivation layer 6;

manufacturing an electrode pattern on the surface of the passivation layer by means of an ultraviolet lithography technology, and then opening an electrode window by means of an RIE etching technology;

20nm thick Pd and 200nm thick Au were deposited at the electrode windows as lead electrodes 5 by electron beam deposition techniques, and then the devices were annealed at 300 ℃ for 300S by means of a rapid annealing technique.

Example 2:

selecting a high-resistance Ge substrate 1 with a doping concentration of 1 × 10¹³cm^-3By means of UV lithographyMaking five absorption region patterns on the surface of the Ge substrate 1, wherein the width of a single absorption region is 20 mu m, and the thickness of the used photoresist is about 3 mu m and can be used as a masking agent in the subsequent ion implantation process;

implanting impurity B into the absorption region 3 by multiple ion implantation processes to a depth of about 1 μm and a doping concentration of about 5 × 10¹⁶cm^-3；

Manufacturing an electrode region pattern on the surface of the Ge substrate 1 by means of an ultraviolet lithography technology, wherein the electrode region width is 100 micrometers;

implanting impurity B into the electrode region 2 again by multiple ion implantation processes to an implantation depth of about 1 μm and a doping concentration of about 3 × 10¹⁸cm^-3；

Depositing a layer of Si with the thickness of 200nm on the surface of the Ge substrate 1 by means of PECVD technology₃N₄As a device passivation layer 6;

manufacturing an electrode pattern on the surface of the passivation layer by means of an ultraviolet lithography technology, and then opening an electrode window by means of an RIE etching technology;

20nm thick Pd and 200nm thick Au were deposited at the electrode windows as lead electrodes 5 by electron beam deposition techniques, and then the devices were annealed at 300 ℃ for 300S by means of a rapid annealing technique.

Example 3:

selecting a high-resistance Ge substrate 1 with a doping concentration of 1 × 10¹³cm^-3Ten absorption region patterns are manufactured on the surface of the Ge substrate 1 by means of an ultraviolet lithography technology, a single absorption region is 10 microns wide, and the thickness of the used photoresist is about 3 microns and can be used as a masking agent in the subsequent ion implantation process;

implanting impurity B into the absorption region 3 by multiple ion implantation processes to a depth of about 1 μm and a doping concentration of about 2 × 10¹⁶cm^-3；

Manufacturing an electrode region pattern on the surface of the Ge substrate 1 by means of an ultraviolet lithography technology, wherein the electrode region width is 100 micrometers;

implanting impurity B into the electrode region 2 again by multiple ion implantation processes to an implantation depth of about 1 μm and a doping concentration of about 3 × 10¹⁸cm^-3；

Depositing a layer on the surface of the Ge substrate 1 by means of PECVD technology200nm thick Si₃N₄As a device passivation layer 6;

manufacturing an electrode pattern on the surface of the passivation layer by means of an ultraviolet lithography technology, and then opening an electrode window by means of an RIE etching technology;

20nm thick Pd and 200nm thick Au were deposited at the electrode windows as lead electrodes 5 by electron beam deposition techniques, and then the devices were annealed at 300 ℃ for 300S by means of a rapid annealing technique.