Abstract: The invention relates to a method of manufacturing a semiconductor device in which a polycrystalline or amorphous silicon oxide layer 3, which is provided on a silicon oxide layer 2 on a monocrystalline silicon substrate 1 and which is in contact with the silicon substrate 1 via an opening 4 in the silicon layer 2, is recrystallized by means of a heat treatment in the presence of means for concentrating the heat at the opening 4. In a simple and inexpensive manner, these means consist of a second silicon oxide layer 5 and a second polycrystalline silicon layer 6, the second silicon oxide layer 5 having a thickness at the openings 4 which is smaller than that of the rest of the layer 5.