Abstract Some experimental results are reported and discussed. The n+p junction leakage currents and the MOS generation lifetimes of wafers pretreated by the 1G method can be improved by 1-3 and 1-2 orders of magnetitute respectively, while the yields of diodes mode from silicon wafers pretreated by the chlorine oxidation gettring are approximately 3 times of those untreated. It is suggested that a combination of 2 or more defect control methods are necessary to meet the increasingly stringent demands of silicon substrates quality required for LSI, VLSI circuits.