Patent ID: 7407869
Filing Date: 2008-08-05
Classification: C30B,H01L

Abstract:
1. A method for manufacturing a free-standing substrate made of a semiconductor material, which comprises: providing a first assembly by bonding of a nucleation layer of a first material to a support of a second material at a bonding interface being defined and located between facing surfaces of the nucleation layer and the support, wherein the nucleation layer is applied onto the support by direct bonding with molecular adhesion; growing, by epitaxy on the nucleation layer, a substrate of a layer of a third material to form a second assembly with the substrate attaining a sufficient thickness to be free-standing, with at least the substrate being heated to an epitaxial growth temperature, wherein the third material is a wide bandgap material; and selecting the coefficients of thermal expansion of the second and third materials to be different from each other by a thermal expansion differential, determined as a function of the epitaxial growth temperature or subsequent application of external mechanical stresses, such that, as the second assembly cools from the epitaxial growth temperature, stresses are induced in the bonding interface to facilitate detachment of the nucleation layer and the substrate from the support.