The critical doses required to form a continuous buried stoichiometric oxide layer for 70 keV oxygen implantation either during implantation, ΦnormalcI , or after implantation and annealing, ΦnormalcA are ≈7×1017 O+/cm2 and ≈3×1017 O+/cm2 , respectively. The dislocation density in the silicon overlayer and the distribution and density of silicon islands in the buried SiO2 layer of the annealed (70 keV) SIMOX (separated by implantation of oxygen) samples are strongly dependent on the oxygen dose (Φ) and the target temperature false(Tnormalifalse) . Good quality thin‐film SIMOX layers with a low threading dislocation density in the silicon overlayer and low density of silicon islands in the buried SiO2 layer have been produced by implantation of 3.3×1017 O+/cm2 at 680°C.