| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 91 === The technology of modified diamond-like carbon (DLC) films by plasma enhanced chemical vapor deposition has been developed in this study. Besides, a novel technology to deposit hydrogen-free DLC films by particle-free hollow cathode arc discharge is also attempted. Diamond-like carbon films were employed for a variety of industry applications owing to their unique properties including high hardness, high dielectric constant, scratch resistance, excellent thermal conductivity, oxidation and chemical resistance, etc. However, the high compressive stress and poor thermal stability of DLC films limited their applications especially in high temperature conditions. As a result, we tried to improve thermal resistance of DLC films by incorporating a high concentration of silicon in the films. Acetylene was employed as the carbon source, and argon was used to sputter Si target for low temperature depositions. Low stress and thermally stable silicon-containing DLC films were deposited on the silicon wafer substrates. We found that the hardness decreased with increasing the concentration of silicon. When the atomic percent of silicon was higher than 50 %, the DLC films stress was only 0.48 GPa, and the films was stable up to 600℃, in comparison to the conventional undoped DLC films with a high stress of 2.13 GPa and thermal stability only below 400℃.However, the hardness was decreased from 18.6 GPa to 10.9 GPa when the atomic percent of silicon was increased from 0 % to 50 %.The nanostructures and bondings of the films were analyzed by SEM, TEM, FTIR, ESCA and Raman spectroscopy to study the structure-property relationship.
Hydrogen-free DLC films were also deposited by particle-free hollow cathode arc discharge. By employing a variety of anode target designs, we found that high sp3carbon nanostructures could be deposited at -250V substrate bias (ENI RPG50, bipolar pulse duty cycle 50% in 250 kHz), and the hardness of hydrogen-free DLC films was 18.2 GPa. High thermal stability was correlated with the high nanostructures containing a high concentration of sp3 carbon.
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