Investigation of reactive high power impulse magnetron sputtering processes using various target material–reactive gas combinations

The two most important issues limiting reactive high power impulse magnetron sputtering (HIPIMS) process applicability until recently were the absence of suitable reactive HIPIMS control means and the limited capability of HIPIMS power supplies in terms of arc handling. The significant advancement has been made recently by the development of the optical plasma monitoring (PM)-based process control technology for reactive HIPIMS [Surface & Coatings Technology 204 (2010) 2159–2164]. The initial studies of reactive HIPIMS processes however have only covered Ti–O2 target material–reactive gas system. s paper the recently developed PM-based active feedback control technology was applied to explore further reactive HIPIMS processes now using a variety of different target material and reactive gas combinations. Data for hysteresis behaviour and process control using either PM or constant gas flow methods for Ti–O2, Ti–CO2, Cr–O2, Cr–C2H4, Al–O2, and Zn:Al–O2 material–gas systems is presented and compared. In all cases the processes were found to exhibit hysteresis behaviour. The magnitude and features of the hysteresis loop were found to depend strongly on a particular metal–reactive gas pair. Similar to AC and DC reactive sputtering processes the hysteresis behaviour in reactive HIPIMS was found to be more pronounced for the gases that have high chemical affinity for a metal sputter target. The PM-based process control technology monitoring either metal or gas plasma emissions was shown to provide accurate control and stable operation of reactive HIPIMS discharges.