The present disclosure relates to a process for fabricating a plurality of semiconductor-on-insulator structures, the insulator being a layer of silicon dioxide having a thickness smaller than 50 nm, each structure comprising a semiconductor layer placed on the silicon dioxide layer, the fabrication process comprising a step of heat treating the plurality of structures, which heat treatment step is designed to partially dissolve the silicon dioxide layer, the heat treatment step being carried out in a non-oxidizing atmosphere and the pressure of the non-oxidizing atmosphere being lower than 0.1 bar.