Synthesis of hard diamond-like carbon films by double-pulse high-power impulse magnetron sputtering

Abstract

Hard diamond-like carbon (DLC) films were prepared by a double-pulse high-power impulse magnetron sputtering (HiPIMS) at an Ar gas pressure of 0.6 Pa and average power of 90 W. The objective was to increase the sp3 C content in the films, in comparison to single-pulse HiPIMS. The first HiPIMS plasma temporally evolved during a pulse-on time of the voltage source with a width of about 15 μs and the discharge current reached 50 A corresponding to 1.8 A/cm2. After the application of the first-pulse voltage for HiPIMS, a second-pulse voltage was applied to produce the second HiPIMS from the afterglow plasma. External setting parameters such as the time interval between the first pulse and second pulse and the target current in the second HiPIMS were varied. The fraction of sp3 C–C bonds was estimated from the ratio of the peak intensity related to sp3 C–C bonds to the total peak intensity of C1s core spectrum in X-ray photoelectron spectroscopy. The fraction of sp3 C–C bonds in the DLC film prepared by double-pulse HiPIMS reached 52% with a hardness of 36.5 GPa.