Method for fabricating silicon-on-insulator wafer

Claim 1

A method for fabricating silicon-on-insulator wafer, comprising the steps of: providing a first, a second and a third silicon substrates being comprised of bulk silicon; forming a first oxide film on one side of the first silicon substrate; forming a first impurity layer within the second silicon substrate with a selected depth; forming an isolation film in one side of the second silicon substrate; forming a second oxide film having even surface on the second silicon substrate; bonding the second oxide film of the second silicon substrate and the first oxide film of the first silicon substrate; performing a first polishing, a wet-etching and a second polishing processes in sequence until the impurity layer is removed, in the other side of the second silicon substrate; forming a second impurity layer within the second silicon substrate adjoining the first isolation film; forming a second isolation film in the other side of the second silicon substrate; forming a third oxide film having even surface on the other side of the second silicon substrate; forming a fourth oxide film on the third silicon substrate; bonding a fourth oxide film of the third silicon substrate and the third oxide film of the second silicon substrate; dividing a first wafer and a second wafer by the second impurity layer as a boundary line, wherein the first wafer includes the first isolation film and a first silicon layer which is some portion of the second silicon substrate where the first isolation film is formed, and the second wafer includes the second isolation film and a second silicon layer which is some portion of the second silicon substrate where the second isolation film is formed; and polishing the first and the second silicon layers using the first and the second isolation films of the first wafer and the second wafer as a polishing stopper, respectively.

Claim 2

A method for fabricating silicon-on-insulator wafer, comprising the steps of: providing a first, a second and a third silicon substrates being comprised of bulk silicon; forming a first oxide film on one side of the first silicon substrate; forming a first impurity layer within the second silicon substrate with a selected depth; forming an isolation film in one side of the second silicon substrate; forming a second oxide film having even surface on the second silicon substrate; bonding the second oxide film of the second silicon substrate and the first oxide film of the first silicon substrate; performing a first polishing, a wet-etching and a second polishing processes in sequence until the impurity layer is removed, in the other side of the second silicon substrate; forming a second impurity layer within the second silicon substrate adjoining the first isolation film; forming a second isolation film in the other side of the second silicon substrate; forming a third oxide film having even surface on the other side of the second silicon substrate; forming a fourth oxide film on the third silicon substrate; bonding a fourth oxide film of the third silicon substrate and the third oxide film of the second silicon substrate; dividing a first wafer and a second wafer by the second impurity layer as a boundary line, wherein the first wafer includes the first isolation film and a first silicon layer which is some portion of the second silicon substrate where the first isolation film is formed, and the second wafer includes the second isolation film and a second silicon layer which is some portion of the second silicon substrate where the second isolation film is formed; and polishing the first and the second silicon layers using the first and the second isolation films of the first wafer and the second wafer as a polishing stopper, respectively.