Rajesh Ganesan^1,2, Anas Ghailane², Lucca Pernagidis², Christos Pernagidis^2
1The University of Sydney, Sydney, Australia
²Avaluxe Coating Technologies, Fürth, Germany
We report on the dual-role implementation of bipolar High-Power Impulse Magnetron Sputtering (HiPIMS) for both substrate pre-treatment and carbon-based film deposition, demonstrating its potential to significantly enhance coating performance. By introducing a positive voltage pulse following the conventional negative HiPIMS pulse, we achieved controlled ion acceleration by forming a transient double layer in the afterglow plasma. This enabled highly efficient physical sputter cleaning of substrates, with elevated ion energy fluxes contributing to enhanced surface activation and contaminant removal. Our time-resolved diagnostics confirmed that ion energies approached the applied positive voltage, facilitating effective substrate etching before deposition.
In the subsequent deposition phase, we employed bipolar HiPIMS to grow diamond-like carbon (DLC) films and observed a marked improvement in film quality. Specifically, we achieved an sp³ fraction exceeding 45%, reduced argon incorporation, and a corresponding increase in film hardness from 42 to 53 GPa and residual stress from 6 to 3.1 GPa with a 5% maximum variation. By optimizing target materials—including glassy carbon—we mitigated arcing events and improved plasma stability. Our analysis of ion flux dynamics across species provided further insight into the role of ion mass, ionization energy, and sputter yield in shaping the deposition environment. These results demonstrate that bipolar HiPIMS offers an effective strategy for in-situ substrate cleaning and enables the synthesis of high-density carbon coatings with superior mechanical properties, paving the way for next-generation surface engineering applications.