Optimization of plasma etching of SiO2 as hard mask for HgCdTe dry etching

Yiyu Chen; Zhenhua Ye; Changhong Sun; Shan Zhang; Wen Xin; Xiaoning Hu; Ruijun Ding; Li He

doi:10.1117/12.2247502

1 November 2016 Optimization of plasma etching of SiO₂ as hard mask for HgCdTe dry etching

Yiyu Chen, Zhenhua Ye, Changhong Sun, Shan Zhang, Wen Xin, Xiaoning Hu, Ruijun Ding, Li He

Proceedings Volume 10157, Infrared Technology and Applications, and Robot Sensing and Advanced Control; 101573L (2016) https://doi.org/10.1117/12.2247502
Event: International Symposium on Optoelectronic Technology and Application 2016, 2016, Beijing, China

Abstract

HgCdTe is one of the dominating materials for infrared detection. To pattern this material, our group has proven the feasibility of SiO2 as a hard mask in dry etching process. In recent years, the SiO₂ mask patterned by plasma with an auto-stopping layer of ZnS sandwiched between HgCdTe and SiO₂ has been developed by our group. In this article, we will report the optimization of SiO₂ etching on HgCdTe. The etching of SiO₂ is very mature nowadays. Multiple etching recipes with deferent gas mixtures can be used. We utilized a recipe containing Ar and CHF₃. With strictly controlled photolithography, the high aspect-ratio profile of SiO₂ was firstly achieved on GaAs substrate. However, the same recipe could not work well on MCT because of the low thermal conductivity of HgCdTe and CdTe, resulting in overheated and deteriorated photoresist. By decreasing the temperature, the photoresist maintained its good profile. A starting table temperature around -5°C worked well enough. And a steep profile was achieved as checked by the SEM. Further decreasing of temperature introduced profile with beveled corner. The process window of the temperature is around 10°C. Reproducibility and uniformity were also confirmed for this recipe.

Citation Download Citation

Yiyu Chen, Zhenhua Ye, Changhong Sun, Shan Zhang, Wen Xin, Xiaoning Hu, Ruijun Ding, and Li He "Optimization of plasma etching of SiO₂ as hard mask for HgCdTe dry etching", Proc. SPIE 10157, Infrared Technology and Applications, and Robot Sensing and Advanced Control, 101573L (1 November 2016); https://doi.org/10.1117/12.2247502

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