Dry etching method

Abstract

There is provided a method for anisotropic etching of a fine resist pattern at a practically useful etching rate wherein micro-loading effects are suppressed. If a resist layer is etched using an NH.sub.3 /N.sub.2 gas mixture, while the temperature of a sample wafer is controlled to be not higher than 50.degree. C., a reaction product containing at least N, C and O is produced. The micro-loading effects are suppressed because deposition and sputtering of the reaction product occur competitively on the wafer surface. Since etching of the ion mode is accelerated by N.sub.2, the etching rate as well as anisotropy is improved. There ia also provided a method of supplying sulfur to a NH.sub.3 -containing etching reaction system and utilizing the yielded ammonium sulfide for sidewall protection for further improving anisotropy. In more detail, sulfur is introduced by ion implantation into an area to be etched, at least the surface of a member of an apparatus provided in the vicinity of the sample wafer is formed of a sulfur-based material, or a sulfur compound such as H.sub.2 S is added to an etching gas. Sulfur is supplied into the reaction system by sputtering with the first two methods, and by decomposition of the sulfur compound in the gaseous phase with the latter method.

Dependencies are inferred from the claim text.