Single-phase aluminum nitride films by dc-magnetron sputtering

Abstract

Single-phase aluminum nitride films were deposited onto fused quartz and single-crystal sapphire by current-controlled, reactive, de magnetron sputtering from an aluminum metal target. Optical and structural properties were observed to correlate systematically with the composition of the sputter gas over a wide range of nitrogen partial pressures. A transition in the electrical conductivity of the deposited films occurred as a function of N2 partial pressure. This transition is driven by the condition of the target surface. When the N2 partial pressure was high and the target surface was substantially covered with AlNx, the deposited film was insulating, stoichiometric AlN. When the N2 partial pressure was low and the target surface was substantially Al°, the deposited film was conducting, substoichiometric AlNx.