Patent ID: 7749858

Claim:
A process for producing an MOS transistor on a silicon substrate placed on a buried oxide layer, said transistor being produced in an active substrate zone defined by an isolating region, the process comprising: defining the isolating region; producing a MOS transistor gate and MOS transistor source and drain regions, wherein between the source and drain regions there is a channel that the MOS transistor gate extends above, wherein the isolating region is defined by localized formation of a zone of material that can be selectively etched with respect to silicon, localized formation comprising: performing a germanium ion implantation in the isolating region; annealing the substrate so as to locally convert silicon into a silicon-germanium alloy; and selectively etching said zone of material to form an etched feature and depositing a dielectric material in the etched feature, wherein selectively etching is carried out after the MOS transistor gate has been produced.