A process for avoiding formation of an Si—SiO2—H2 environment during a dissolution treatment of a semiconductor-on-insulator structure that includes a carrier substrate, an oxide layer, a thin layer of a semiconductor material and a peripheral ring in which the oxide layer is exposed. This process includes encapsulating at least the exposed oxide layer of the peripheral ring with semiconductor material by performing a creep thermal treatment; and performing an oxide dissolution treatment to reduce part of the thickness of the oxide layer. In this process, the semiconductor material that encapsulates the oxide layer has a thickness before the oxide dissolution that is at least twice that of the oxide that is to be dissolved, thus avoiding formation of an Si—SiO2—H2 environment on the peripheral ring where the oxide layer would otherwise be exposed.