A comparative study of direct current magnetron sputtering and high power impulse magnetron sputtering processes for CNx thin film growth with different inert gases

Abstract

Reactive direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HiPIMS) discharges of carbon in different inert gas mixtures (N2/Ne, N2/Ar, and N2/Kr) were investigated for the growth of carbon-nitride (CNx) thin films. Ion mass spectrometry showed that energies of abundant plasma cations are governed by the inert gas and the N2-to-inert gas flow ratios. The population of ion species depends on the sputter mode; HiPIMS yields approximately ten times higher flux ratios of ions originating from the target to process gas ions than DCMS. Exceptional are discharges in Ne with N2-to-Ne flow ratios < 20%. Here, cation energies and the amount of target ions are highest without influence on the sputter mode. CNx thin films were deposited in 14% N2/inert gas mixtures at substrate temperatures of 110°C and 430°C. The film properties show a correlation to the substrate temperature, the applied inert gas and sputter mode. The mechanical performance of the films is mainly governed by their morphology and composition, but not by their microstructure. Amorphous and fullerene-like CN0.14 films exhibiting a hardness of ~ 15 GPa and an elastic recovery of ~ 90% were deposited at 110°C in reactive Kr atmosphere by DCMS and HiPIMS. © 2016 Elsevier B.V. All rights reserved