Dynamics of processes during the deposition of ZrO_2 films by controlled reactive high-power impulse magnetron sputtering: A modelling study

摘要

A time-dependent parametric model was applied to controlled reactive high-power impulse magnetron sputtering (HiPIMS) depositions of stoichiometric ZrO_2 films, carried out in our laboratories, (ⅰ) to clarify the complicated dynamics of the processes on the target and substrate surfaces during voltage pulses, and (ⅱ) to corroborate the importance of the O_2 inlet configuration (position and direction) which strongly affects the O_2 dissociation in the discharge and the chemisorption flux of oxygen atoms and molecules onto the substrate. The repetition frequency was 500 Hz at the deposition-averaged target power densities of 25 Wcm~(-2), being close to a target power density applicable in industrial HiPIMS systems, and 50 Wcm~(-2) with a pulse-averaged target power density up to 2 kWcm~(-2). The pulse duration was 50 μs. For the experimental conditions with the to-substrate O_2 inlets, the deposition-averaged target power density of 50 Wcm~(-2), and the oxygen partial pressure of 0.05 Pa (being close to the mean value during controlled depositions), our model predicts a low compound fraction, changing between 8% and 12%, in the target surface layer at an almost constant high compound fraction, changing between 92% and 93%, in the substrate surface layer during the pulse period (2000 μs). The calculated deposition rate of 89 nm/min for these films is in good agreement with the measured value of 80 nm/min achieved for optically transparent stoichiometric ZrO_2 films prepared under these conditions.