Plasma parameter investigation during plasma-enhanced chemical vapor deposition of silicon-containing diamond-like carbon films
In this work, tetramethylsilane-based plasma-enhanced chemical vapor deposition (PECVD) processes were studied, and the deposited silicon-containing diamond-like carbon (DLC) films were analyzed. The main goal was to identify correlations between plasma parameters and the film structure and properties. The electron temperature, gas temperature, and hydrogen and silicon particle densities in these plasmas were calculated using optical emission spectroscopy measurements; the electron density and elastic electron collision rate were determined using self-excited electron resonance spectroscopy. The elemental composition of the films was determined by glow discharge optical emission spectroscopy, and the hardness and Young's modulus were characterized using nanoindentation. The plasma parameters of the gas temperature and electron temperature revealed stringent correlations with the film composition and properties and thus can already monitor the resulting properties during the deposition process. Increasing the gas temperature using power variation leads to reduced incorporation of silicon and hydrogen in the diamond-like carbon films with a simultaneous increase of the film hardness. However, a gas temperature increase using a higher gas flow rate results in a decrease in the film hardness and an increase in the silicon and hydrogen contents. These results are promising concerning the use of plasma parameters for process control of CVD processes.