Effects of a-Si:H resist vacuum-lithography processing on HgCdTe

A vacuum-compatible process for carrying out lithography on Hg^sub 1-x^Cd^sub x^Te and CdTe films was previously demonstrated. It was shown that hydrogenated amorphous silicon (a-Si:H) could be used as a dry resist by projecting a pattern onto its surface using excimer laser irradiation and then developing that pattern by hydrogen plasma etching. Pattern transfer to an underlying Hg^sub 1-x^Cd^sub x^Te film was then carried out via Ar/H^sub 2^ plasma etching in an electron cyclotron resonance (ECR) reactor. Despite the successful demonstration of pattern transfer, the possibility of inducing harmful effects in the Hg^sub 1-x^Cd^sub x^Te film due to this vacuum lithography procedure had not been explored. Here we present structural and surface compositional analyses of Hg^sub 1-x^Cd^sub x^Te films at key stages of the a-Si:H vacuum lithography procedure. X-ray diffraction double crystal rocking curves taken before and after a-Si:H deposition and after development etching were identical, indicating that bulk structural changes in the Hg^sub 1-x^Cd^sub x^Te film are not induced by these processes. Cross-section transmission electron microscopy studies show that laser-induced heating in the 350 nm thick a-Si:H overlayer is not sufficient to cause structural damage in the underlying Hg^sub 1-x^Cd^sub x^Te surface. In vacuo surface analysis via Auger electron spectroscopy and ion scattering spectroscopy suggest that the hydrogen plasma development process produces Hg-deficient surfaces but does not introduce C contamination. However, after ECR plasma etching into the Hg^sub 1-x^Cd^sub x^Te film, the measured x value is much closer to that of the bulk. [PUBLICATION ABSTRACT]