Process for fabricating a wiring layer of aluminum or aluminum alloy on

Abstract

In the fabrication of an aluminum or aluminum alloy wiring layer on a semiconductor device by dry etching using a gas containing chlorine species, a plasma exposure step inserted into the dry etching process in order to avoid the problems due to using a chlorine radical etchant. One half thickness of the aluminum layer, which is selectively masked by a resist mask film, on a semiconductor substrate is etched by a reactive ion etching technique using an etchant gas composed of CCl.sub.4 +BCl.sub.3, and then exposed to a plasma of a gas composed of CF.sub.4 +O.sub.2 generated by RF power. After the plasma exposure, the remaining thickness of the aluminum film is etched off under the same conditions as in the preceeding reactive ion etching. As the result, the amount of side etching is reduced to one half that of the case without the plasma exposure step, and corrosion originating from aluminum chlorides, products of the reactive ion etching, is eliminated. And further, the residual polysilicon layer, which is usually formed when Al-Si film is etched by using a gas containing chlorine as a reactive species, is also reduced.