Crystalline alumina coatings by reactive ac magnetron sputtering

Abstract

Alumina coatings were deposited on silicon (111 orientation) substrates by reactive ac magnetron sputtering. Film deposition was done using Al targets and three O2∕Ar gas flow rate ratios at 5kW power. X-ray diffraction studies showed that films were crystalline and contained several phases of alumina. Secondary ion mass spectroscopy analyses were used to measure O∕Al atomic ratio and Ar and H concentrations in the films. Hydrogen content in the coatings depended on the O2 partial pressure used during sputtering and also on the arrival rate of Al and O species on the substrates and seemed to influence the crystallinity of the coatings.