Voltage controlled, reactive planar magnetron sputtering of AlN thin films

Three operating modes for planar magnetron sputtering are investigated for the purpose of controlling the stoichiometry of AlNx (0?x?1) films: (1) controlled gas flow rates at constant power, (2) controlled power at constant flow rates, and (3) controlled cathode voltage at constant flow rates. Whereas modes (1) and (2) are found to exhibit runaway transitions associated with target coverage, mode (3) is shown to provide a means for stable operation for any degree of target coverage (0?x?1).