A process comprises the following steps: a) provision of a chamber suitable for receiving the plurality of structures, b) circulation of a gas stream in the chamber so that the chamber has a non-oxidizing atmosphere, c) heat treatment of the plurality of structures at a temperature above a threshold value above which the oxygen present in the oxide of the dielectric diffuses through the active layer reacts with the semiconductor material of the active layer and produces a volatile material, the process being noteworthy in that the step b) is carried out so that the gas stream has a rate of circulation between the plurality of structures greater than the rate of diffusion of the volatile material into the gas stream.