Patent ID: 8765576

Claim:
A method of manufacturing a laminated substrate, comprising: forming an oxide film on at least a surface of a first substrate having a hardness of equal to or more than 150 GPa in Young's modulus; smoothing the oxide film by mechanically and chemically polishing a surface of the oxide film such that a surface roughness of the oxide film is equal to or less than 0.5 nm rms; implanting hydrogen ions or rare gas ions, or mixed gas ions thereof from a surface of a second substrate to form an ion-implanted layer inside the substrate; laminating the first substrate and the second substrate through at least the oxide film, and then detaching the second substrate in the ion-implanted layer to form a laminated substrate; and heat-treating the laminated substrate and diffusing outwardly the oxide film, such that a thickness of the oxide film is reduced to a minimum thickness required to compensate for a roughness of the surface of the first substrate, such that the surface of the oxide film is at substantially the same elevation as the highest peak of the surface of the first substrate.