Rotatable magnetron sputtering of aluminium in continuous and high power pulse modes using different strength magnetic arrays

Abstract

This paper reports preliminary results of industrial size (152 mm target O.D.) rotatable magnetron sputtering of Al target in direct current (DC) and High Power Impulse Magnetron Sputtering (HIPIMS) modes using two standard commercially available magnetic arrays: standard strength array (as used for DC and AC processing) and a lower strength ‘RF’ array [i.e. as used for radio frequency (RF) magnetron sputtering]. A comparison of processes resulted in by combining the different magnetic arrays and power modes is made in terms of magnetic field distribution on the cathode surface, magnetron characteristics, process characteristics and deposition rates. Optical emission spectroscopy (OES) revealed enhanced sputtered Al flux ionisation in the HIPIMS discharge monitored 64 mm away from the target surface when using the ‘RF’ array. Importantly, the results of this work (at the processing conditions investigated) demonstrate that at the same average power the deposition rate of Al using HIPIMS in conjunction with the ‘RF’ array is substantially the same as that obtained for the ‘standard’ strength balanced array and DC power. This indicates that the magnetic field design of the ‘RF’ magnetic array affects favourably the sputtered flux transport perpendicular to the target surface by altering mass transport direction and minimising effects that reduce deposition rate (e.g. ion return effect). Arc rate is also reduced significantly (approximately ten times) if the low strength ‘RF’ array is used.