Patent ID: 6949478

Claim:
A method of forming an oxide film comprising: a first step to form a first oxide film on a surface of a substrate body by contacting at least one of oxygen or, molecules including oxygen, or a mixture of oxygen and molecules including oxygen and inert gas each in a gas phase, or a solution containing oxygen and molecules including oxygen to the surface of the substrate body on which on oxide film is to be formed; a second step of heating the surface of the substrate body and the oxide film in one of a gas phase of an inert gas or in vacuum; and a third step to form a second oxide film having a thickness larger than said first oxide film formed on the substrate body by strengthening bonding between atoms constituting the surface of the substrate and oxygen in said first oxide film by means of thermally processing the surface of said substrate body and said first oxide film under a temperature higher than that in said first step in at least one of oxygen, molecules including oxygen, or a mixture of oxygen and molecules including oxygen and inert gas, each being in a gas phase.