Reactive sputtering deposition of SiO2 thin films

SiO2 layers were deposited in a UHV chamber by 1 keV Ar + ion sputtering from a high purity silicon target, using different values of the oxygen partial pressure (5×10 -6 -2×10 -4 mbar) and of the ion beam current on the target (1.67-6.85 mA). The argon partial pressure during operation of the ion gun was 1×10 -3 mbar. The substrate temperature was held at 550 °C and the films were deposited to a thickness of 12.5-150 nm, at a rate from 0.0018-0.035 nm s -1 . Structural characterization of the deposited thin films was performed by Ru- therford backscattering spectrometry (RBS analysis). Reactive sputtering was proved to be efficient for the deposition of silica at 550 °C, an oxygen partial pressure of 2×10 -4 mbar (ion beam current on the target of 5 mA) or, at a lower deposition rate, ion beam current of 1.67 mA and an oxygen partial pressure of 6×10 -5 mbar. One aspect of these investigations was to study the consumption of oxygen from the gas cylinder, which was found to be lower for higher depo- sition rates.