Fabrication of mercury cadmium telluride (HgCdTe) devices has always been a challenging task due to sensitive nature of the material. I-generation devices requiring 50～60 μm wide patterning feature in size can be successfully done using wet chemical etching. Dry processing, particularly high density plasma etching is capable for reducing pixel pitch and dramatically improving fill factors needed for II-generation and III-generation devices such as high-density focal plane arrays, avalanche photodiodes, two-colour detectors and multi-spectral detectors. The deep, narrow trenches are required to be with high aspect ratios, smooth sides and high uniformity, all the requirements promoted the development of dry etching. By summarizing and analyzing the related papers published in English periodicals since 2000, the developments of wet and dry processing techniques used for HgCdTe device fabrication are described with emphasis on dry etching techniques. An in-depth understanding of etching mechanisms requires knowledge of diverse fields of chemistry, physics, and electrical sciences. To fabricate a device with large areas, the etching process needs to be optimized for good reproducibility and uniformity.