| 摘要 |
A dry etching method whereby high anisotropy can be achieved while providing sidewall protection effects by using an appropriate alternative substance to a carbonaceous polymer. A target material layer is etched by using etching gas containing a nitrogen based compound and a sulfur based compound capable of forming free sulfur (S) in a plasma when dissociated by electric discharges while a pattern sidewall is protected by a sulfur nitride based compound occurring from the gaseous phase. The sulfur nitride based compound is composed mainly of polythiazyl (SN)x, which causes no particle pollution because it will be removed from a wafer through sublimation or decomposition when the wafer is heated to temperatures above 130 DEG C. For instance, a polysilicon layer or an Al based material layer can be etched into an anisotropic shape by using S2Cl2/N2 mixed gas. Particularly, a silicon based compound layer can be etched while preventing chloroflurocarbon (CFC) gas effectively. The sidewall protection film composed of (SN)x has such excellent resistance to attacks by radicals or incident ions that a pattern formed into an anisotropic shape will not be deformed even when over-etched with radicals.
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