Temporal, spatial and spectroscopic study of plasma emission on Cu target in bipolar HiPIMS

Bipolar high power impulse magnetron sputtering introduces new possibilities to affect positive ions created during the negative discharge pulse in order to tailor thin films with specific parameters. This paper studies plasma emission in different experimental conditions during different phases of the positive pulse with spectral, spatial and temporal resolution. It is found that predominantly the working gas gives rise to plasma emission during the positive pulse. The plasma emission is observed only in regions of low magnetic confinement, forming a 'mushroom-like' shape in the middle of the target or a 'dome-like' shape on the outer parts of the target. An explanation of the discharge kinetics is proposed based on the acquired data.