| abstract |
Disclosed is a process for etching semiconductor materials with a high etch rate against an insulator mask using a novel etchant gas mixture. The mixture consists of a fluorochlorohydrocarbon (e.g., CCl₂F₂, CHCl₂F₂, CCl₄ or CCl₃F), SF₆, O₂ and an inert gas (e.g. He). The preferred gas mixture contains 2/1 ratio of the fluorochlorocarbon to SF₆ and the following composition: 1-4 % of SF₆, 3-10 % of O₂, 74-93 % of He and 3-10 % of fluorochlorohydrocarbon. The etch rate of silicon (or silicide) against an oxide mask using this etchant gas mixture under normal etching conditions is high, on the order of 30-40. An impressive feature of the process is shape control of trenches by mere manipulation of the RIE system power. |