阅读说明：本技术 一种平面碲镉汞雪崩二极管探测器及其制备方法 (Planar mercury cadmium telluride avalanche diode detector and preparation method thereof ) 是由 张智超 喻松林 张轶 于 2019-09-26 设计创作，主要内容包括：本发明提出了一种平面碲镉汞雪崩二极管探测器及其制备方法,用以降低平面碲镉汞雪崩二极管探测器柱面结和球面结耗尽区中的电场强度,进而降低相应的隧穿电流,提高雪崩击穿电压,提升线性模式下的增益。所述方法,包括：在碲镉汞表面沉积钝化层；通过常规掺杂对碲镉汞进行P型掺杂；通过常规掺杂在P型碲镉汞材料上进行N型掺杂,形成N<Sup>+</Sup>中心区,高掺杂N<Sup>+</Sup>保护环和低掺杂N<Sup>-</Sup>区；生成穿透钝化层的位于高掺杂N<Sup>+</Sup>中心区和碲镉汞P型掺杂区的光敏元电极接触孔和公共电极接触孔；在电极接触孔形成光敏元电极和公共电极。(The invention provides a planar tellurium-cadmium-mercury avalanche diode detector and a preparation method thereof, which are used for reducing the electric field intensity in the cylindrical junction and spherical junction depletion regions of the planar tellurium-cadmium-mercury avalanche diode detector, further reducing the corresponding tunneling current, improving the avalanche breakdown voltage and improving the gain in a linear mode. The method comprises the following steps: depositing a passivation layer on the mercury cadmium telluride surface; carrying out P-type doping on mercury cadmium telluride through conventional doping; n-type doping is carried out on the P-type tellurium-cadmium-mercury material by conventional doping to form N + Center region, highly doped N + Guard ring and low doped N ‑ A zone; creating a highly doped N located through the passivation layer + A contact hole for the photosensitive element electrode and a contact hole for the common electrode in the central region and the HgCdTe P-type doped region; and forming a photosensitive element electrode and a common electrode in the electrode contact hole.)

1. A method for preparing a planar HgCdTe avalanche diode detector is characterized by comprising the following steps:

depositing a passivation layer on the mercury cadmium telluride surface;

carrying out P-type doping on mercury cadmium telluride through conventional doping;

n-type doping is carried out on the P-type tellurium-cadmium-mercury material by conventional doping to form N⁺Center region, highly doped N⁺Guard ring and low doped N^-A zone;

generating a photosensitive element electrode contact hole and a common electrode contact hole which penetrate through the passivation layer and are positioned in the highly doped N + central region and the mercury cadmium telluride P-type doped region;

and forming a photosensitive element electrode and a common electrode in the electrode contact hole.

2. The method of claim 1, wherein the high doping of N is performed⁺The guard ring is formed of at least one guard ring.

3. The method of claim 2Method, characterized in that said highly doped N⁺The guard ring is composed of 1-4 layers of guard rings.

4. Method according to claim 2 or 3, characterized in that two adjacent layers are highly doped N⁺The distance between the guard rings is 2-8 μm.

5. A method according to claim 2 or 3, characterized in that the innermost layer is highly doped with N⁺The distance between the guard ring and the tellurium-cadmium-mercury highly-doped N + central area is 2-8 mu m.

6. The method as claimed in claim 1, wherein depositing a passivation layer on the mercury cadmium telluride surface specifically comprises:

depositing a cadmium telluride passivation layer on the mercury cadmium telluride surface; or

Cadmium telluride and zinc sulfide are sequentially deposited on the mercury cadmium telluride surface to form a passivation layer.

7. The method of claim 6, wherein the cadmium telluride is from 30 to 500nm thick and the zinc sulfide is from 0 to 500nm thick.

8. The method of claim 1, wherein forming the photosensor electrode and the common electrode in the electrode contact hole comprises:

sequentially growing a chromium layer and a first gold layer in the electrode contact hole to form a photosensitive element electrode and a common electrode; or

And sequentially growing a chromium layer, a first gold layer, a platinum layer and a second gold layer in the electrode contact hole to form a photosensitive element electrode and a common electrode.

9. The method of claim 8, wherein the thickness of the chromium layer is 10-200 nm, the thickness of the first gold layer is 50-500 nm, the thickness of the platinum layer is 0-500 nm, and the thickness of the gold layer is 0-300 nm.

10. A planar HgCdTe avalanche diode detector, characterized in that, the planar HgCdTe avalanche diode detector is prepared by any one of the methods of claims 1-9.

Technical Field

The invention relates to the technical field of infrared detectors, in particular to a planar mercury cadmium telluride avalanche diode detector and a preparation method thereof.

Background

The HgCdTe avalanche diode detector can work in Geiger mode and linear mode separately based on different work bias voltages. In a Geiger mode, the work bias voltage of the HgCdTe avalanche diode detector is higher than the avalanche breakdown voltage, the amplitude of an output signal is irrelevant to the amplitude of a received photoelectric signal, and the next signal detection can be carried out only after the detector is quenched by an external circuit; under the linear mode, the work bias of the HgCdTe avalanche diode detector is lower than the avalanche breakdown voltage, the gain of the HgCdTe avalanche diode detector changes along with the bias voltage, and the received photoelectric signal can be amplified and output continuously and proportionally at high speed without an external quenching circuit.

The mercury cadmium telluride avalanche diode detector belongs to the third generation infrared detector technology, and the mercury cadmium telluride material has the characteristic of single carrier excited avalanche in a specific component interval, so that the avalanche amplification with the characteristic of nearly no excess noise can be realized. The tellurium-cadmium-mercury avalanche photodiode has the characteristics of high sensitivity, high gain bandwidth product, high signal-to-noise ratio and the like, can continuously work at high speed without blind time in a linear mode, and has wide application prospects in the fields of optical fiber communication, space communication, three-dimensional laser radars, astronomical observation, atmospheric detection and the like.

The mercury cadmium telluride avalanche diode detector usually adopts a PIN structure, and specific implementation modes include a plane type, a mesa type and an annular ring type. When the HgCdTe avalanche diode detector works, the applied bias voltage mainly falls in the depletion region of the PN junction. The actually formed PN junction of the conventional planar HgCdTe avalanche diode detector is greatly different from the ideal situation, as shown in FIG. 1, wherein 11 is a HgCdTe P-type doped region, 12 is a HgCdTe low-doped N-region, 13 is a HgCdTe high-doped N + region, 14 is a HgCdTe surface passivation film layer, 15 is a detection photosensitive element electrode, and 16 is a common electrode. The actual PN junction can be divided into a transverse cylindrical junction, a longitudinal plane junction and a spherical junction at a corner, the curvature radius of the cylindrical junction and the spherical junction is smaller than that of the plane junction, so that the electric field at the cylindrical junction and the spherical junction is seriously concentrated, the tunneling current related to the electric field at the cylindrical junction and the spherical junction is far higher than that at the plane junction, the avalanche breakdown voltage at the cylindrical junction and the spherical junction is lower than that at the plane junction, and the effective working bias range and the corresponding gain range of the mercury cadmium telluride avalanche diode detector in a linear mode are limited.

Disclosure of Invention

The invention aims to solve the technical problem of reducing the electric field intensity in the cylindrical junction and spherical junction depletion regions of a planar mercury cadmium telluride diode detector, further reducing the corresponding tunneling current, improving the avalanche breakdown voltage and improving the gain in a linear mode, and provides the planar mercury cadmium telluride diode detector and a preparation method thereof.

The invention adopts the technical scheme that the preparation method of the planar HgCdTe avalanche diode detector comprises the following steps:

depositing a passivation layer on the mercury cadmium telluride surface;

carrying out P-type doping on mercury cadmium telluride through conventional doping;

n-type doping is carried out on the P-type tellurium-cadmium-mercury material by conventional doping to form N⁺Center region, highly doped N⁺Guard ring and low doped N^-A zone;

generating a photosensitive element electrode contact hole and a common electrode contact hole which penetrate through the passivation layer and are positioned in the highly doped N + central region and the mercury cadmium telluride P-type doped region;

and forming a photosensitive element electrode and a common electrode in the electrode contact hole.

In one possible embodiment, the highly doped N⁺The guard ring is formed of at least one guard ring.

In one possible embodiment, the highly doped N⁺The guard ring is composed of 1-4 layers of guard rings.

In one possible embodiment, two adjacent layers are highly doped with N⁺The distance between the guard rings is 2-8 μm.

In one possible embodiment, the innermost layer is highly doped with N⁺The distance between the guard ring and the tellurium-cadmium-mercury highly-doped N + central area is 2-8 mu m.

In one possible implementation, depositing a passivation layer on the mercury cadmium telluride surface specifically includes:

depositing a cadmium telluride passivation layer on the mercury cadmium telluride surface; or

Cadmium telluride and zinc sulfide are sequentially deposited on the mercury cadmium telluride surface to form a passivation layer.

In one possible embodiment, the cadmium telluride has a thickness of 30-500 nm, and the zinc sulfide has a thickness of 0-500 nm.

In one possible implementation mode, the forming of the light sensitive element electrode and the common electrode in the electrode contact hole specifically includes:

sequentially growing a chromium layer and a first gold layer in the electrode contact hole to form a photosensitive element electrode and a common electrode; or

And sequentially growing a chromium layer, a first gold layer, a platinum layer and a second gold layer in the electrode contact hole to form a photosensitive element electrode and a common electrode.

In a possible embodiment, the thickness of the chromium layer is 10 to 200nm, the thickness of the first gold layer is 50 to 500nm, the thickness of the platinum layer is 0 to 500nm, and the thickness of the gold layer is 0 to 300 nm.

The invention also provides a planar mercury cadmium telluride avalanche diode detector which is prepared by any one of the methods.

By adopting the technical scheme, the invention at least has the following advantages:

the planar mercury cadmium telluride avalanche diode detector and the preparation method thereof form the highly doped N + protection ring on the P-type mercury cadmium telluride material, when a reverse bias voltage is loaded on a PN junction, a depletion region of a central PN formed by a highly doped N + central region expands outwards along with the increase of the reverse bias voltage, when the depletion region contacts the protection ring, the depletion region of the central PN junction and the depletion region of the protection ring PN are penetrated, the width of the depletion region is increased, an electric field of the central PN junction extends outwards, the electric field intensity at a cylindrical junction and a spherical junction is reduced, the corresponding tunneling current is reduced, the avalanche breakdown voltage is improved, and the mercury cadmium telluride diode detector can work under higher bias voltage in a linear mode to obtain higher gain.

Drawings

FIG. 1 is a schematic diagram of a planar HgCdTe avalanche diode detector;

FIG. 2 is a flow chart of a method for manufacturing a planar HgCdTe avalanche diode detector according to an embodiment of the invention;

FIG. 3 is a schematic structural diagram of a planar HgCdTe avalanche diode detector according to an embodiment of the invention.

Detailed Description

To further explain the technical means and effects of the present invention adopted to achieve the intended purpose, the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

It should be noted that the terms "first", "second", and the like in the description and the claims of the embodiments of the present invention and in the drawings described above are used for distinguishing similar objects and not necessarily for describing a particular order or sequence. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that the embodiments described herein may be practiced otherwise than as specifically illustrated or described herein.

Reference herein to "a plurality or a number" means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.

The curvature radius of a cylindrical junction and a spherical junction of a conventional planar mercury cadmium telluride diode detector is smaller than that of the planar junction, so that electric fields at the cylindrical junction and the spherical junction are seriously concentrated, the tunneling current related to the electric fields at the cylindrical junction and the spherical junction is far higher than that at the planar junction, the avalanche breakdown voltage at the cylindrical junction and the spherical junction is lower than that at the planar junction, and finally the problem that the gain in a linear mode is difficult to improve is caused.

In view of this, the embodiments of the present invention provide a method for increasing depletion widths of a cylindrical junction and a spherical junction through a protection ring structure, so as to reduce electric field intensities in depletion regions of the cylindrical junction and the spherical junction, thereby reducing corresponding tunneling leakage, increasing avalanche breakdown voltage, and finally increasing gain in a linear mode.

As shown in fig. 2, which is a schematic flow chart of an implementation of a method for manufacturing a planar mercury cadmium telluride avalanche diode detector provided by an embodiment of the present invention, the method includes the following steps:

and S21, depositing a passivation layer on the mercury cadmium telluride surface.