US 5,685,950 A · Dry etching method

Abstract

A dry etching method is disclosed in which a first polysilicon layer is etched, using an ECR plasma of an etching gas containing a bromine-based gas and a rare gas, as a sidewall protective film is formed by a deposit mainly composed of SiBr, for forming a tapered gate electrode. Since SiBr.sub.x is efficiently generated by a radical reaction of Br.sup.* assisted by an ion-assist mechanism by the rare gas, and has a long residence time under a low gas pressure, it can be deposited efficiently on a patterned sidewall surface. Since the sidewall protective film produced with the present dry etching method, is free of SiO.sub.x, particle contamination may be diminished. Since post-processing of a shorter time duration suffices for removing the sidewall protective film, erosion of the gate insulating film is not produced. Thus the semiconductor device having the fine multi-layer interconnection structure may be improved in reliability and yield.

Claims12

Dependent claims

A method for dry etching of a layer of silicon-based material on a substrate comprising the steps of:

forming a mask layer on the layer of the silicon-based material for exposing an area to be etched;
etching the exposed area by providing an etching gas consisting of a bromine-based gas, an oxygen-based gas and a rare gas with a rate of flow of the rare gas being more than a rate of flow of the bromine-based gas, creating an ECR plasma with the etching gas under a gas pressure of 1.3 to 13.3 Pa to etch the exposed area while depositing a deposit composed mainly of silicon bromide on sidewalls created by the etching and controlling the amount of oxygen-based gas to limit the amount of oxygen in the deposit, and then
removing the deposit on the sidewalls with a fluorine plasma process.

Dependencies are inferred from the claim text.

Dry etching method

Life of this patent

Dry etching method

Life of this patent

Abstract

Claims12