DLC films formed by hybrid pulse plasma coating (HPPC) system

A new coating system was developed which consists fundamentally of plasma CVD (chemical vapor deposition) and ion-mixing. The system employs pulsed-gas introduction, pulsed-plasma generation and plasma base ion implantation (PBII). In this paper the formation of DLC films by the HPPC system is reported. The plasma densities were measured using a Langmuir probe and a 10-GHz microwave interferometer. DLC films were formed on the surface of workpieces using hydrocarbon gases by the HPPC system, with monitoring plasma density during the coating process. Raman spectra of DLC films by the HPPC system are similar in shape to those by ion-plating, and the fractions of amorphous and graphite components in Raman spectrum gained by segregated four peaks decreased with the decrease of CH4/C7H8 partial pressure ratios. The reason is considered that the larger the deposition rates of films become, the smaller the ion-mixing effects are. Furthermore, as the CH4/C7H8 ratio becomes as low as 1, this phenomenon becomes more apparent. For the further study, the plasma density as well as the change in gas pressure in the chamber must be monitored for the formation of uniform DLC films.