Patent ID: 7144766

Claim:
The method for manufacturing a semiconductor integrated circuit device, comprising the steps of: (a) forming a tungsten film over a first principal surface of a wafer; (b) subjecting a portion on the first principal surface of the wafer containing silicon as a main component to an oxidation treatment at a first temperature of 600 degrees centigrade or more in a mixed gas atmosphere containing hydrogen and moisture without oxidizing the tungsten film; and (c) washing the first principal surface of the wafer with a solution which is a neutral or weakly alkaline water or chemical solution substantially not containing hydrogen peroxide after the step (b), wherein said solution has properties in the vicinity of the boundary between tungsten region and tungsten tetraoxide negative ion region in the oxidation-reduction potential and pH phase diagram for tungsten-water system, wherein the pH of the water or chemical solution is 7 or more and less than 10.5, and wherein the water or chemical solution is used for the washing in a flowing state.