Tungsten-silicide reoxidation process including annealing in pure nitrogen and subsequent oxidation in oxygen

摘要

A tungsten silicide reoxidation technique for forming a reoxidation layer in a CMOS device is disclosed. After forming an insulated gate member, which has a silicon-rich tungsten silicide layer overlying a polysilicon layer, it is first oxidized and the oxide is removed to expose WSi for forming a particular source/drain doped device. Then it is annealed in a substantially pure nitrogen ambient for a given time period. A subsequent growth of the reoxidation layer over the gate member by introducing oxygen results in a substantially planarized surface. The combination between tungsten and oxygen is prevented.