Method for leading out electrical properties of mercury cadmium telluride pn junction and detector chip

Abstract

The invention discloses a method for leading out electrical properties of a mercury cadmium telluride pn junction and a detector chip. The method comprises the following steps: sequentially forming acadmium telluride layer and a zinc sulfide layer on the surface of a mercury cadmium telluride wafer of which the interior is provided with the pn junction; forming photoresist corresponding to areasexcept the contact hole area to be formed on the surface of the zinc sulfide layer; taking the photoresist as a mask, and removing zinc sulfide corresponding to a to-be-formed contact hole region through a wet etching process; removing the photoresist; taking the zinc sulfide layer treated by the wet etching process as an etching mask, and etching the cadmium telluride layer and part of the mercury cadmium telluride material corresponding to the contact hole region to be formed by a dry etching process to form a contact hole pattern; forming a metal electrode in the contact hole region throughan electrode deposition process and an ion beam etching process. Therefore, the zinc sulfide layer is used as the etching mask to etch the contact hole, and then the metal electrode deposition is directly carried out, and therefore the ohmic contact effect between the tellurium-cadmium-mercury material and the metal electrode can be improved.

Description

Technical field[0001]The invention relates to the technical field of detector chips, in particular to a method and a detector chip for the electrical properties of mercury cadmium telluride pn junction.Background technique[0002]Mercury cadmium telluride is an important material for the preparation of infrared detectors. Because of its adjustable band gap, the detection spectrum extends from the short-wave band to the very long-wave band. It has the advantages of high photoelectric detection efficiency and is widely used in early warning detection, infrared Military and civilian fields such as reconnaissance and imaging guidance. Detector chip preparation is the core of infrared detection technology. The process of preparing the chip mainly includes semiconductor device processes such as photolithography, wet chemistry, ion implantation, passivation, electrode preparation, and dry etching. Etching and electrode deposition are among the device processes. The key link of the infrared f...

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Problems solved by technology

[0003] In the existing HgCdTe pn junction electrical performance extraction process, the fresh HgCdTe surface obtained after dry etching has strong chemical activity. If the liquid is exposed to the air environment for a long time, it will be oxidized. In addition, during the wet stripping process, the photoresist is easy to remain on the bottom of the etching hole. The above problems may cause the metal and HgCdTe material An additional parasitic resistance is generated at the interface between the electrodes, which affects the effect of the ohmic contact of the electrodes

The parasitic resistance causes the contact resistance of each pixel of the infrared detector to be different. Since the contact resistance has a certain voltage division effect, it will affect the working voltage applied to each pixel. After photoelectric conversion, the output signal of the pixel will be Differences occur, which in turn leads to poor response consistency of the detector chip

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