Surface Treatment of Polyethylene Terephthalate Using Plasma Ion Implantation Based on Direct Coupling of RF and High-Voltage Pulse

Plasma immersion ion implantation employing hybrid radio-frequency (RF) and high-voltage (HV) pulses via a single feedthrough is an effective surface modification method. In this technique, the sample holder is connected to both the RF generator and the HV modulator in order to generate a high-density plasma in the vicinity of the sample. HV pulses are applied to the sample in between the RF pulses to conduct ion implantation. Polyethylene terephthalate (PET) samples were modified using an C₂H₂ plasma generated by this technique, and diamond-like-carbon films were successfully deposited. In this process, the pulsed HV changed from 2.5 to 10 kV with an RF power ranging from 0 to 150 W and an RF of 13.56 MHz. The C₂H₂ gas pressure was maintained at 1.0 Pa with a processing time of 15 min. Cleaning effects were observed without arcing damage with increasing sample bias from 2.5 to 10 kV. The negative bias and RF were observed to influence the water contact angles of treated PET samples. The plasma-implanted surface became more hydrophilic with increasing sample bias and RF power, respectively.