Cathode Current Density Distributions in High Power Impulse and Direct Current Magnetron Sputtering Modes

Abstract

AbstractDuring the operation of high power impulse magnetron sputtering discharges, peak currents in excess of 1 000 A may be observed, leading to large instantaneous power levels. To investigate this method of operation, a series of planar probes have been constructed that allow for the spatial and temporal variations of current across the surface of a cathode to be assessed. These measurements provide information on the flux of charged particles to and from the cathode whilst it is being sputtered. Under operating conditions that led to a peak current of 140 A, measured current densities varied spatially from ∼0.1 to 1.5 A · cm−2. By the use of a simple model, the measured current densities were used to predict the sputtering rate of the cathode, which allowed for the erosion profile and target lifetime to be estimated. The results suggest that, with regard to sputtering, operating in HiPIMS mode may be less energy efficient than operating in DC mode, but may achieve a higher target utilisation fraction.