阅读说明：本技术 探测器芯片及其制备方法 (Detector chip and preparation method thereof ) 是由 陈晓静 张传杰 张冰洁 姚柏文 黄立 于 2020-04-02 设计创作，主要内容包括：本发明涉及一种探测器芯片,包括碲镉汞薄膜和芯片结构,芯片结构包括pn结、读出电路和铟柱,pn结形成于碲镉汞薄膜的背面上,读出电路位于碲镉汞薄膜的背面侧并且通过铟柱与pn结连接。另外还涉及探测器芯片的制备方法,包括：将碲镉汞薄膜固定于载体上,其中,碲镉汞薄膜的正面朝向载体；去除碲镉汞薄膜背面的衬底；在碲镉汞薄膜背面上形成pn结,该pn结通过铟柱连接读出电路；去除载体。本发明提供的探测器芯片及其制备方法,通过在碲镉汞薄膜背面成结,该pn结即形成于碲镉汞薄膜的背面高组分材料区(也即外延界面处),可以防止芯片反型,降低探测器芯片的漏电流,增强芯片响应信号,从而显著地提高探测器的工作性能。(The invention relates to a detector chip which comprises a mercury cadmium telluride film and a chip structure, wherein the chip structure comprises a pn junction, a reading circuit and an indium column, the pn junction is formed on the back surface of the mercury cadmium telluride film, and the reading circuit is positioned on the back surface side of the mercury cadmium telluride film and is connected with the pn junction through the indium column. In addition, the preparation method of the detector chip comprises the following steps: fixing the HgCdTe thin film on a carrier, wherein the front surface of the HgCdTe thin film faces the carrier; removing the substrate on the back of the tellurium-cadmium-mercury film; forming a pn junction on the back of the mercury cadmium telluride film, wherein the pn junction is connected with a reading circuit through an indium column; and removing the carrier. According to the detector chip and the preparation method thereof provided by the invention, the junction is formed on the back surface of the HgCdTe thin film, and the pn junction is formed in the back high-component material region (namely, the epitaxial interface) of the HgCdTe thin film, so that the inversion of the chip can be prevented, the leakage current of the detector chip is reduced, the response signal of the chip is enhanced, and the working performance of the detector is obviously improved.)

1. A detector chip comprises a mercury cadmium telluride film and a chip structure, wherein the chip structure comprises a pn junction, a reading circuit and an indium column, and is characterized in that: the pn junction is formed on the back surface of the mercury cadmium telluride film, and the readout circuit is positioned on the back surface side of the mercury cadmium telluride film and is connected with the pn junction through the indium column.

2. The detector chip of claim 1, wherein: and the front surface and/or the back surface of the tellurium-cadmium-mercury film is/are covered with a protective film.

3. The detector chip of claim 1, wherein: the protective film is a ZnS film.

4. A preparation method of a detector chip is characterized by comprising the following steps:

s1, fixing the HgCdTe thin film on a carrier, wherein the front surface of the HgCdTe thin film faces the carrier;

s2, removing the substrate on the back of the HgCdTe thin film;

s3, forming a pn junction on the back of the HgCdTe thin film, wherein the pn junction is connected with a reading circuit through an indium column;

s4, removing the carrier.

5. The preparation method according to claim 4, wherein S3 specifically comprises the following steps:

performing a chip pre-process on the back of the HgCdTe film without the substrate, forming a pn junction by injecting B ions into the junction,

growing indium columns on the pn junction;

and performing flip-chip interconnection on the grown indium columns and the reading circuit.

6. The method of claim 4, wherein: in S1, the mercury cadmium telluride film is first plated with a protective film and then fixed on a carrier.

7. The method of claim 6, wherein: the protective film is a ZnS film.

8. The method of claim 6, wherein: before the protective film is plated, the HgCdTe film is cleaned to remove dirt on the surface of the HgCdTe film.

9. The method of claim 4, wherein: the mercury cadmium telluride film is fixed on the carrier through a binder, wherein the binder comprises black wax and a D limonene solvent, and the proportion is that 1g of the black wax is dissolved in every 10-15 ml of the D limonene solvent.

10. The method of claim 9, wherein: and S4, soaking the molded chip body obtained in the step S3 in a trichloroethylene solution, heating the trichloroethylene solution to boil, and naturally dropping the carrier after the adhesive is melted.

Technical Field

The invention belongs to the technical field of infrared detectors, and particularly relates to a detector chip and a preparation method thereof.

Background

The leakage current of the device is the current of the pn junction under the condition of not receiving any infrared radiation and reverse bias, and is a characteristic parameter reflecting the essence of the detector. The increase of the device leakage current can cause the increase of the noise of the device and the reduction of the junction impedance, the size of the junction impedance can also influence the efficiency of a reading circuit for reading a photoresponse signal from the device, and the increase of the device leakage current can also cause the increase of the dark current of the device, thereby causing the uniformity of the focal plane device to be poor.

The component of the HgCdTe thin film material is one of important parameters of the HgCdTe infrared detector, and the larger the epitaxial component is, the larger the zero-bias resistance R is₀The smaller, quality factor R when the device is dominated by diffusion current₀The size of A directly determines the size of leakage current of the device, the larger the leakage current is, the larger the noise is, and in order to reduce the generation of noise, the leakage current must be reduced, and the epitaxial composition is improved. In the actual process, due to the liquid phase epitaxy of the tellurium-cadmium-mercury material, a high growth temperature will cause an obvious component interdiffusion effect between the tellurium-zinc-cadmium substrate and the tellurium-cadmium-mercury epitaxial layer, and meanwhile, in the epitaxy process, the partial condensation of cadmium will also cause a component depletion effect of the mother solution in a local area, thereby causing the cadmium component on the surface of the tellurium-cadmium-mercury epitaxial layer to be low and the interface cadmium component to be high. In the chip process surface at the present stage, the surface passivation is carried out on the surface of the epitaxial material (namely, a low component surface), and then the B ion implantation is carried out, so that the inversion is easily caused, and the low cadmium component causes many mercury vacancy defects, the forbidden bandwidth is small, the chip leakage current is obviously increased, and the performance of the device is reduced.

Disclosure of Invention

The invention relates to a detector chip and a preparation method thereof, which can at least solve part of defects in the prior art.

The invention relates to a detector chip which comprises a mercury cadmium telluride film and a chip structure, wherein the chip structure comprises a pn junction, a reading circuit and an indium column, the pn junction is formed on the back surface of the mercury cadmium telluride film, and the reading circuit is positioned on the back surface side of the mercury cadmium telluride film and is connected with the pn junction through the indium column.

In one embodiment, the front and/or back of the HgCdTe thin film is covered with a protective film.

In one embodiment, the protective film is a ZnS film.

The invention also relates to a preparation method of the detector chip, which comprises the following steps:

s1, fixing the HgCdTe thin film on a carrier, wherein the front surface of the HgCdTe thin film faces the carrier;

s2, removing the substrate on the back of the HgCdTe thin film;

s3, forming a pn junction on the back of the HgCdTe thin film, wherein the pn junction is connected with a reading circuit through an indium column;

s4, removing the carrier.

As one embodiment, S3 specifically includes the following steps:

performing a chip pre-process on the back of the HgCdTe film without the substrate, forming a pn junction by injecting B ions into the junction,

growing indium columns on the pn junction;

and performing flip-chip interconnection on the grown indium columns and the reading circuit.

In one embodiment, in S1, the mercury cadmium telluride film is first coated with a protective film and then fixed to a support.

In one embodiment, the protective film is a ZnS film.

As one embodiment, the HgCdTe thin film is cleaned before the protective film is plated so as to remove dirt on the surface of the HgCdTe thin film.

In one embodiment, the mercury cadmium telluride film is fixed on the carrier through a binder, wherein the binder comprises black wax and a D-limonene solvent, and the proportion of the black wax is that 1g of the D-limonene solvent is dissolved in 10-15 ml of the D-limonene solvent.

In one embodiment, in S4, the molded chip body obtained in S3 is immersed in a trichloroethylene solution, the trichloroethylene solution is heated to boiling, and the carrier is dropped naturally after the adhesive is melted.

The invention has at least the following beneficial effects:

according to the detector chip and the preparation method thereof provided by the invention, the junction is formed on the back surface of the HgCdTe thin film, and the pn junction is formed in the back high-component material region (namely, the epitaxial interface) of the HgCdTe thin film, so that the inversion of the chip can be prevented, the leakage current of the detector chip is reduced, the response signal of the chip is enhanced, and the working performance of the detector is obviously improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a cross-sectional view of a mercury cadmium telluride film provided in an embodiment of the present invention before back-side junction formation;

FIG. 2 is a cross-sectional view of a rear side of a HgCdTe thin film provided by an embodiment of the invention after junction formation;

fig. 3 is a flowchart of a manufacturing process of a detector chip according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.