Patent ID: 6432834
Filing Date: 2002-08-13
Classification: H01J,H01L

Abstract:
A method of increasing the etch selectivity of a metal suicide film with respect to a polysilicon film during plasma enhanced etching of a stacked film, the stacked film comprising the polysilicon film and the metal silicide formed on a substrate, the method comprising:(a) plasma etching the metal silicide film with a plasma source power applied to an etch chamber, by accelerating etch gas ions through application of a bias power to the substrate; (b) chemically adsorbing the etch gas ions to the metal silicide film and oxidizing the polysilicon film exposed using the etch gas ions, by continuously applying the plasma source power to the etch chamber and applying a first bias power level less than or equal to a level at which the etch gas ions are not accelerated to the substrate; and (c) accelerating the etch gas ions by applying the plasma source power to the etch chamber and a second bias power level to the substrate, the second bias power level being greater than the first bias power level, so that the etch gas ions adsorbed on the metal silicide film in step (b) are etched out by the accelerated etch gas ions, wherein an oxide film formed on the exposed polysilicon film in step (b) serves as a film for preventing etching of the polysilicon film.