Process stabilization during reactive high power impulse magnetron sputtering of Ce/Gd target

In this study, a simple approach to stabilize reactive high power impulse magnetron sputtering process in the transition zone between the metallic and oxide modes was investigated. The method is based on the use of peak current value as feedback and control signal. It was shown that the change in the state of the target surface causes almost instantaneous change in the amplitude and shape of the current pulses. To stabilize the deposition process, the pulse frequency was regulated to maintain a constant maximum discharge current. The hysteresis behavior and the variations of the pulse current waveforms over a wide range of O₂ flow rates and pulse frequencies during a reactive HiPIMS deposition of gadolinia-doped ceria (GDC) thin films in an Ar-O₂ atmosphere were examined. Stable process conditions were maintained at the O₂ flow from 0.9 to 3.9 sccm by adjustment of the pulse frequency from 1.45 to 2.9 kHz. GDC films deposited using peak current regulation exhibited a stable stoichiometry and high deposition rate in comparison with films obtained without process stabilization.