ASPECTS AND RESULTS OF LONG-TERM STABLE DEPOSITION OF AL2O3 WITH HIGH-RATE PULSED REACTIVE MAGNETRON SPUTTERING

Several essential conditions for the long-term stable deposition of highly insulating layers by reactive magnetron sputtering from metal targets are studied. The following aspects are considered: design of the magnetron and of the deposition arrangement, electric potential of the electrodes surrounding the plasma, position of the gas inlet, appropriate control of the gas inlet, power supply and process stabilization method. The defect level of the deposited layers could be reduced by several orders of magnitude compared with layers deposited with a normal magnetron arrangement as a consequence of arc suppression on a microsecond time scale. When the magnetron discharge is pulsed at medium frequency (10-200 kHz), the deposition process stabilizes and the arcing tendency is decreased. The deposited Al2O3 layers had a maximum thickness of 50 mum. The dependences of the deposition rate up to a maximum of 240 nm min-1 and several other film properties (e.g. optical and mechanical) on process parameters such as the power density at the target, the reactive ps flow and the discharge voltage were investigated.