Mid-frequency reactive sputtering of dielectrics: Al2O3

Reactive sputtering of dielectrics is done today mainly by applying pulsed DC or AC power, all modulated in the range of 1 kHz–1 MHz frequencies (mid-frequency range). This frequency range is chosen to avoid arcing and, at the same time, to obtain a substantial deposition rate. Pulsed DC is used when a simple one-magnetron system is preferred. Unfortunately, such approach does not solve the ‘disappearing’ anode problem. The disappearing anode and arcing problems are solved simultaneously using mid-frequency AC power and either dual-anode (DAS) or dual-magnetron (DMS) systems. Applying biasing to conductive substrates in the above deposition techniques is a serious problem. In the case of the DASs and the DMSs, biasing could be applied by connecting the substrate to a center tap of an isolation transformer. Reactive sputtering of Al2O3 was investigated and analyzed in this work to develop this biasing approach.