Simulation results of the gas rarefaction and target ion evolution in a chopped high power impulse magnetron sputtering discharge

The high power impulse magnetron sputtering (HiPIMS) technique has recently been improved experimentally to deposit titanium films with several short micro-pulses that are decomposed from one single pulse. The additional control parameters cause a totally different current characteristic and result in a high deposition rate in these so-called chopped-HiPIMS (c-HiPIMS) sequences. Owing to the difficulty in digging deeply into the details of parameter variations through the experimental method, simulation works are adopted to exploit the complex mechanism. Here, the ionization region model is used to simulate the short micro-pulse discharge in HiPIMS. It is found that short pulse on-time tμon, long pause off-time tμoff, and the large number of micro-pulses within a single voltage pulse are factors that result in a higher deposition rate and are relevant to the gas rarefaction and the metal ion running away behavior.