Effect of peak target power on the properties of Cr thin films sputtered by HiPIMS in deep oscillation magnetron sputtering (DOMS) mode

Abstract

The advent of High-power Impulse Magnetron Sputtering (HiPIMS) and its variant Modulated Pulsed Power Magnetron Sputtering (MPPMS) allowed a new knob to control the flux of sputtered species, i.e., a new knob to control the kinetic effects of the growing film. Recently, a new design of the MPPMS pulses has been proposed to reduce arc generation. This form of high power pulses has been named deep oscillation magnetron sputtering (DOMS). In this work, the influence of the kinetic effects induced by a DOMS discharge on Cr sputtered thin films was studied and compared to direct current magnetron sputtering (DCMS) discharge. The Cr thin films were deposited with increasing peak power at the same average power (1.2kW) in order to minimize changes in the thermal effects that also influence film growth. The influence of the peak power on the morphology, structure and mechanical properties of Cr thin films was studied. The Cr films deposited by DCMS have a columnar morphology, a [110] preferential orientation, hardness between 7.2 and 8.5GPa and a maximum Young's modulus of 255GPa, value always lower than that for bulk material. Although substrate bias potential up to −110V was used, some porosity always remained in the DCMS films. The deposition rate of the Cr films deposited by DOMS with increasing peak power decreases from 60 to 30% of DCMS deposition rate. The films also have a [110] preferential orientation. Increasing the peak power changes the film morphology from columnar to dense, increases the hardness up to 17GPa, increases the lattice parameter and decreases the grain size. The Young's modulus of the films is always close to the bulk material value showing that all the films are porosity free.