Abstract: A method of manufacturing a semiconductor substrate having dielectric regions is disclosed. The method comprises steps of forming an amorphous silicon layer on the surface of a monocrystalline silicon substrate, annealing a selected surface of said amorphous silicon layer to form a crystallized region intended as an active region, subjecting the obtained structure to a thermal oxidation process to form said dielectric isolation regions, and removing an oxide coating formed on the surface of said crystallized region.