Investigation of the Effect of Hydrogen Gas as Raw Material for DLC Film Preparation

Abstract

For reducing the frictional losses on the sliding surfaces of mounting parts and improving the wear resistance in order to extend the life of the component, diamond-like carbon (DLC) film coating has been considered, in recent years. However, reduction of the long processing time involved is desirable for mass production. For achieving this, the effect of mixing hydrocarbon gas and hydrogen gas in the deposition process is compared, and the differences in the resulting DLC films are determined in this study. DLC films are deposited on Si wafers through radio frequency plasma chemical vapor deposition (RF-PECVD), with a mixture of methane gas and hydrogen (dilution gas) as the raw material. In addition, DLC films are prepared by mixing acetylene gas with hydrogen gas for comparison, and the effect of the hydrogen gas mixture on the deposition rate, composition, and hardness of the films is confirmed. When hydrogen gas is mixed with methane gas, the deposition rate increases with the increase in the ratio of hydrogen gas in the raw material, and the percentage of sp³ bonds increases; however, the hardness and elastic modulus decrease. Furthermore, the adhesiveness deteriorates with the increase in the hydrogen gas ratio.

In the case of methane gas mixed with hydrogen gas, the obtained deposition rate increases with the increase in the hydrogen gas mixing ratio, but no such change is observed in the case of acetylene gas.