Effect of tail time of discharge current on film properties in diamond-like carbon deposition by high-frequency inclusion high-power impulse magnetron sputtering

We developed a high-frequency inclusion high-power impulse magnetron sputtering (HF-HiPIMS) method to reduce droplet formation and improve film functionality. In this work, the effects of the tail time of discharge current on film properties in diamond-like carbon (DLC) deposition were investigated using the HF-HiPIMS method. First, we evaluated the film density using the peak discharge current and explained the adaptive limits of previously used evaluation parameters. Next, we introduced the tail time of the discharge current as a new evaluation parameter and explained the relationship between tail time and film density. In addition, we measured the chemical bonding state, surface roughness, and discharge plasma to evaluate the DLC film prop-erties obtained using the HF-HiPIMS method. The results showed that the HF-HiPIMS method increased the sp3 C-C ratio and decreased the surface roughness of DLC films and provided higher plasma density compared to the conventional unipolar HiPIMS method. Additionally, it was shown that the tail time can be used to control film density.