Conductive transistor structure for a semiconductor device and method for forming same

摘要

A method and structure for a semiconductor device comprises a tungsten-rich tungsten silicide layer interposed between a polysilicon layer and a tungsten nitride layer in a word line stack. The tungsten-rich layer reduces or prevents the formation of an insulative layer which can occur between the polysilicon and the tungsten nitride. The ratio of tungsten to silicon in the tungsten-rich tungsten silicide layer is preferably within a specified range to both prevent formation of a dielectric interface between the tungsten silicide and the tungsten nitride and to ensure that excessive tungsten silicide will not form. Excessive tungsten silicide is not easily etched and may short the transistor gate formed from the word line polysilicon.