Mechanism of silicon exfoliation by hydrogen implantation and He, Li and Si co-implantation [SOI technology]

There has been much interest in reproducing Si exfoliation by H implantation and in understanding the mechanism leading to such a remarkably uniform shearing. We have previously demonstrated that, contrary to the initial speculation, there are in fact three distinct aspects to the process: i) the generation of damage to the crystalline material by the implantation; ii) the unique surface chemistry of hydrogen and silicon that drives the thermal evolution of this damage region and; iii) the creation of internal pressure that ultimately causes exfoliation ofthe overlying Si layer. Therefore, a detailed understanding of the exfoliation mechanism involves the study of initial damage, of H-passivation of various internal structures and of the mechanical forces exerted by trapped gases as a function of hydrogen implantation dose/depth and annealing temperature. In this work, we have used different hydrogen implantation conditions (ion energies ranging from 1 eV to 1 MeV and substrate crystallographic orientations) as well as co-implantation of a variety of other elemental species, in combination with novel spectroscopic configurations, to further explore these different mechanistic aspects.