Macro-loading Effects in Inductively Coupled Plasma Etched Mercury Cadmium Telluride

This paper reports the effect of macro-loading on mercury cadmium telluride (Hg 1− x Cd x Te) and Photoresist (PR) etched in an inductively coupled plasma (ICP). A significant macro-loading effect is observed, which affects the etch rates of both PR and Hg 1− x Cd x Te. It is observed that the exposed silicon area has a significant effect on the PR etch rate, but not on the Hg 1− x Cd x Te etch rate. It is also observed that the exposed Hg 1− x Cd x Te area has a significant effect on the etch rate of the PR, but the exposed PR area does not seem to have an effect on the Hg 1− x Cd x Te etch rate. Further, the exposed Hg 1− x Cd x Te area is shown to affect the etch rate of the Hg 1− x Cd x Te, but there does not seem to be a similar effect for the exposed PR area on the etch rate of the PR. Since the macro-loading affects the selectivity significantly, this effect can cause significant problems in the etching of deep trenches. A few techniques to reduce the effect of macro-loading on the etch rates of the PR and Hg 1− x Cd x Te are listed, herein.