Dry etching method

Abstract

A method for anisotropic dry etching of a layer of a silicon oxide-based material with high etching base selectivity and low contamination without employing fluorocarbonaceous gases, is proposed. Sulfur fluorides with a low F/S ratio, such as S.sub.2 F.sub.2, are employed as an etching gas, and etching is performed by a mechanism in which ions such as SF.sub.x.sup.+ assist a radial reaction by F*. High selectivity with respect to silicon-based material is assured by S deposits thereon when silicon oxide-based material is etched off. Since S may be easily removed by sublimation by wafer heating after etching, contamination by particles is not produced. By previously implanting ions into an area to be etched, or by providing a sulfur-based material in the vicinity of the wafer, sulfur may be sputtered out into an etching system as etching proceeds to improve selectivity with respect to the base silicon. The end point of etching of the layer of the silicon oxide-based material may be acutely determined by detecting a time point at which the intensities of sulfur oxide peaks are decreased abruptly during monitoring an emission or a mass spectrum.

Dependencies are inferred from the claim text.