Patent ID: 8114781

Claim:
A substrate processing method for processing a substrate having a thermally-oxidized film formed by thermal oxidation processing and a nitride film in a chamber, comprising: an oxygen-containing plasma contact step of causing oxygen-containing plasma to be in contact with the substrate; and an HF gas supply step of supplying HF gas toward the substrate with which the oxygen-containing plasma has been in contact, wherein the nitride film comprises a silicon nitride film and is changed to a silicon monoxide film in said oxygen-containing plasma contact step, and wherein, in said HF gas supply step, water molecules are removed from the chamber in a state in which two types of silicon oxide films, which respectively corresponds to the thermally-oxidized film and the silicon monoxide film and have different densities, exist contemporaneously in such a manner that water molecules remain in a silicon oxide film having less density between the two types of silicon oxide films, and the HF gas is supplied to selectively remove the silicon oxide film having less density.