Patent ID: 8513092

Claim:
A method for reducing defect densities at a bonding interface when producing a stacked structure having an ultra thin buried oxide (UTBOX) layer, which comprises: forming a diffusion barrier of a first electrical insulator layer of a thermal oxide on a first substrate at a thickness sufficient to prevent or reduce water diffusion therein; introducing elements into the donor substrate through the first electrical insulator layer to form a weakened layer in the donor substrate; forming a diffusion barrier of a second electrical insulator layer of a thermal oxide on a second substrate at a thickness sufficient to prevent or reduce water diffusion therein, with the second electrical insulation layer being the same in thickness or thinner than the first electrical insulation layer; bonding the first and second substrates together without previously subjecting the substrates or insulator layers to plasma activation by contacting the first and second electrical insulator layers together to form the UTBOX layer between the two substrates, wherein the UTBOX layer has a thickness of less than 50 nm, wherein the first electrical insulator layer has, during bonding, a thickness which is greater than 50% up to 95% of the thickness of the buried oxide layer.