Etchant gas and a method for etching transistor gates

摘要

A method for producing a semiconductor device from a silicon substrate supporting a patterned hardmask layer, a tungsten silicide layer, a polysilicon layer, and a gate oxide layer. The method comprises etching the tungsten silicide layer and the polysilicon layer with an etchant gas comprising carbon monoxide (CO) and chlorine (Cl2). The etchant gas may also include hydrogen bromide (HBr) or a nitrogen-containing gas (e.g., N2).