Effect of H2 and O2 plasma etching treatment on the surface of diamond-like carbon thin film

In this study, we investigated the surface properties of diamond-like carbon (DLC) films for biomedical applications through plasma etching treatment using oxygen (O2) and hydrogen (H2) gas. The synthesis and post-plasma etching treatment of DLC films were carried out by 13.56 MHz RF plasma enhanced chemical vapor deposition (PECVD) system. In order to characterize the surface of DLC films, they were etched to a thickness of approximately 100 nm and were compared with an as-deposited DLC film. We obtained the optimum condition through power variation, at which the etching rate by H2 and O2 was 30 and 80 nm/min, respectively. The structural and chemical properties of these thin films after the plasma etching treatment were evaluated by Raman and Fourier transform infrared (FT-IR) spectroscopy. In the case of as-deposited and H2 plasma etching-treated DLC film, the contact angle was 86.4° and 83.7°, respectively, whereas it was reduced to 35.5° in the etching-treated DLC film in O2 plasma. The surface roughness of plasma etching-treated DLC with H2 or O2 was maintained smooth at 0.1 nm. These results indicated that the surface of the etching-treated DLC film in O2 plasma was hydrophilic as well as smooth.