A plasma-based ion implantation system that can apply both radio frequency wave (RF) and negative high voltage pulses through single feedthrough has been developed. The system was successfully applied to the formation of hydrogenated amorphous carbon (a-C:H) thin films. The a-C:H films were deposited by capacitively coupled continuous wave (CW) RF discharge of pure methane (CH 4 ) or mixture of CH 4 and Ar. Ion implantation by negative high voltage pulse bias was also demonstrated under the pulsed RF discharge of CH 4 . Mechanical properties of the deposited a-C:H films were measured by nano indentation. Maximum hardness and elastic modulus of the film was 23 and 220 GPa, respectively.