PURPOSE: A method for forming gate electrode of semiconductor device is provided to prevent a quality decrease and a fault of a gate oxidation film by performing an annealing process over 5 minutes in a low atmosphere pressure and high temperature vacuum condition before the performance of a spacer process. CONSTITUTION: A gate insulating film(14') is etched for performing a self-align to a gate electrode (20') and a reside of a substrate surface is removed using a wet cleaning process. An annealing process is performed over 5 minutes in a low atmosphere pressure and high temperature vacuum condition before the performance of a spacer process, and then a fluorine is removed from a surface of a tungsten silicide film. A silicon nitration film(22') is deposited at 500 to 2000 angstrom thickness using a low pressure chemical vapor deposition. The silicon nitration film(22') is etched using a dry etching process and then a spacer is formed to a side wall portion of the gate electrode(20').