THE INFLUENCE OF OXYGEN ON SIO2 SPUTTERING

Argon-ion sputtering of thin silicon dioxide films has been studied both in ultrahigh vacuum and in a low pressure oxygen ambient. The variation in ion-induced secondary electron yield with decreasing oxide thickness was used to determine the sputtering yield. The method was found to be a simple and accurate way of in situ measurement of thin-film sputtering. A 30% decrease in sputtering yield was observed for 200-keV Ar ion bombardment when the oxygen pressure was increased from 1×10-8 to 1×10-6 mbar. Secondary electron yield variations were found to give information also on the surface modification process. A mechanism is proposed in which oxygen is incorporated into the oxide due to the ion bombardment. Comparison with ion beam induced oxidation is also made.