Dry etching polysilicon using a bromine-containing gas

Abstract

The present invention provides a dry etching method for achieving a satisfactory anisotropic etching of, for example, a semiconductor wafer, particularly, a polysilicon layer formed on the wafer. In the present invention, a mixed gas comprising a first gas containing Br and a second gas containing a halogen element other than Br, e.g., a mixed gas consisting of a HBr gas and a HCl gas, is introduced into a vacuum chamber. The mixed gas is converted into plasma by applying a high frequency power to an upper electrode 5. The plasma region is irradiated, as desired, with an ultraviolet light. The semiconductor wafer is etched with the plasma. The etching is carried out under optimum conditions. For example, the surface temperature of the semiconductor wafer, i.e., workpiece, is maintained at a level falling within a range of between 70.degree. C. and 120.degree. C. Also, the flow rate ratio of the mixed gas is suitably controlled.

Dependencies are inferred from the claim text.