A high-quality SIMOX wafer was produced by a combination of low-dose implantation and annealing using the ITOX process, which enables precise control of the superficial silicon thickness and improvement of the BOX characteristics, together with an increase in BOX thickness. Recently, a further quality improvement was achieved using nitrogen-doped Czochralski silicon as the SIMOX starting material, which is effective in eliminating shallow surface pits. 300 mm SIMOX samples were manufactured successfully in the late 2000s, showing that the advantage of SIMOX technology will be maintained through the next generation.