Reactive sputtering deposition of SiO2 thin films

Abstract

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 Rutherford 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 deposition rates.