Patent ID: 8563399

Claim:
A process for fabricating a detachable substrate which comprises: supplying an intermediate substrate comprising a buried weakenable region made of semiconductor material, doped using naturally volatile impurities, which is denser in the liquid state than in the solid state and a detachable layer that extends from the buried weakenable region to a front side of the substrate, with the naturally volatile impurities having a vapor pressure of at least 100 pascals at temperatures of 900° C. or below and a thermal diffusion length that is small compared to that provided by the thickness of the intermediate substrate; locally melting part or all of the weakenable region, including at least part of the volatile impurities, to create at least one free surface containing a volume of gas at an interface between the liquefied material of the weakenable region and adjacent substrate material; and recrystallizing the melted portions to form a weakened region that contains in places precipitates of the naturally volatile impurities at the interface.