PLASMA ETCHING METHOD USING GAS MOLECULE CONTAINING SULFUR ATOM

Provided is a plasma etching method whereby it becomes possible to process a film composed of a sole material such as SiO2 and SiN or a composite material containing SiO2 or SiN in a mask-material-selective manner in a semiconductor production process and it also becomes possible to obtain a good vertically processed shape in the processing. General formula (1): Rf1-S-Rf2 (1) (wherein Rf1 represents a monovalent organic group represented by CxHyFz; and Rf2 represents a monovalent organic group represented by CaHbFc.) When a mixed gas containing a gas compound having a thioether backbone represented by formula (1) or the gas compound alone is plasmatized to etch a film composed of a sole material such as SiO2 and SiN or a composite material containing the material, a protection film which has a reduced fluorine atom content compared with the case where a conventional hydrofluorocarbon gas is used and which contains a sulfur atom can be deposited. Therefoe, it becomes possible, for example, to improve the selec