Patent ID: 7491342

Claim:
A manufacturing method of a bonded substrate having a final active layer thickness of 200 nm or less, comprising: a) providing a first silicon wafer as an active layer wafer and a second silicon wafer as a support substrate; b) forming silicon oxide film on a surface of said active layer wafer; c) implanting hydrogen ions into the active layer wafer to form a hydrogen ion implanted layer under the silicon oxide film; d) bonding the active layer wafer and the support substrate such that the silicon oxide film is interposed between the active layer wafer and the support substrate and forms a bonded substrate having an embedded silicon oxide film; e) heat treating the bonded substrate to form regions of high density hydrogen bubbles and cleaving away a portion of the active layer wafer at said regions whereby the non-cleaved active layer wafer of the bonded substrate becomes the active layer of the bonded substrate; f) heat treating the cleaved bonded substrate to enhance bonding strength between the active layer wafer and the support substrate; and g) etching a surface of the active layer of the bonded substrate to control the thickness of said active layer, said etching being carried out using a solution having an etching effect so as to etch in a range of 1nm to 1μm, said solution being a solution having pH 9 or higher and containing alkaline chemicals and an oxidizer.