Hydrophobic and Mechanical Characteristics of Hydrogenated Amorphous Carbon Films Synthesized by Linear Ar/CH4 Microwave Plasma

A 2.45 GHz microwave plasma with linear antenna has been prepared for hydrophobic and wear-resistible surface coating of carbon steel. Wear-resistible properties are required for the surface protection of cutting tools and achieved by depositing a hydrogenated amorphous carbon film on steel surface through linear microwave plasma source that has TE 10- TEM waveguide. Compared to the existing RF plasma source driven by 13.56MHz, linear microwave plasma source can easily generate high density plasma and provide faster deposition rate and wider process windows. In this study, Ar/CH₄ gas mixtures are used for hydrogenated amorphous carbon film deposition. When microwave power of 1000W is applied, 40 cm long uniform Ar/CH₄ plasma could be obtained in gas pressure of 200~400 mTorr. The Vickers hardness measurement of hydrogenated amorphous carbon film on steel surface was evaluated. It was found the optimized deposition condition at Ar : CH₄=25:25 sccm, 300 mTorr with microwave power of 1000W and RF bias power of 100W. By deposition of hydrogenated amorphous carbon film, contact angle on steel surfaces increases from 43.9° to 93.2°.