Patent ID: 7122469

Claim:
A process for the fabrication of a semiconductor integrated circuit device, comprising the steps of: (a) forming a polysilicon film over a gate insulation film containing a silicon oxide film which has been formed over a silicon surface of a wafer; (b) forming a refractory metal film of tungsten or molybdenum over said polysilicon film through a barrier layer of a nitride of tungsten; (c) forming a gate electrode by patterning said polysilicon film and said refractory metal film; and (d) after said step (c), thermally oxidizing said polysilicon film without oxidizing said refractory metal film and said barrier layer, under a gas ambient containing hydrogen, and water vapor synthesized from a mixed gas of oxygen and hydrogen gases by a catalyst, and containing substantially no hydrogen radicals, wherein in said step (d), using an oxidizing furnace and a gas generator connected with said oxidizing furnace, introducing oxygen and hydrogen into said gas generator, and introducing hydrogen and water vapor into said oxidizing furnace, and wherein the introduction of oxygen into said gas generator begins after the beginning of the introduction of hydrogen into said gas generator.