Room Temperature Oxidation of Sputter-Deposited Titanium Films

Abstract

The effects of oxygen partial pressure (0.3 to 1.6 kPa) on the room temperature oxidation behaviour of sputter-deposited titanium films (58 nm in thickness) have been investigated by using a quartz-oscillator microbalance. The titanium films were sputter-deposited onto a quartz oscillator from a pure titanium target or a titanium target partially covered with TiO₂ square tips under argon or argon-1% oxygen atomosphere at 1 Pa pressure. It was found that a major portion of the oxide layer (18-6×10¹⁹ O₂/m²) was formed during the initial fast oxidation process and the initial oxidation rate in the low oxygen partial pressure (0.3-200 Pa), as well as the number of the oxygen sorption layer, depended on the oxygen partial pressure. However, as the oxygen partial pressure increased, the oxidation rate was almost independent of the oxygen partial pressure. The oxygen dissolved during the sputter-deposition from the target (Ti-TiO₂) or from gas phase (Ar-O₂) was found to decrease the initial fast oxidation rate and the number of the sorption layers. After the initial fast oxidation, the oxidation process followed a usual logarithmic rule.