Paper PS-TuP2
Invesitgation of Growth Mechanism of Diamond-like Carbon Film

Tuesday, October 21, 2008, 6:30 pm, Room Hall D

There has been much interest in diamond-like carbon (DLC) films because they have a lot of useful properties: mechanical hardness, chemical inertness, and changeable electrical properties. Further, DLC films were deposited at low temperatures by using plasma process. The films have been used as coating materials for mechanical apparatus. On the other hand, DLC films should be used as electrical and electronic device materials, if the deposition of DLC films has to be controlled in atomic level. Therefore, it is important to understand the growth mechanism of the DLC films. Only a few papers proposed growth mechanism: the deposition rates of DLC films were decreased with the increases of the substrate temperatures; this was because the hydrogen radical generated in plasma was etched the carbon films. However there are a lot of problems left in this model. Thereby, we investigate the growth mechanism in PECVD process by using infrared spectroscopy and deposition/etching rates. We found the decrease of the deposition rates was not due to the hydrogen radical etching, but to the decreases of the adsorption coefficient of hydrocarbon radicals generated in plasma. This was because the etching rates were not increased by the increases of the substrate temperatures. We also found that the types of hydrocarbon species in the DLC films were changed by the substrate temperatures less than 300 degree C during the deposition; in this temperature region the hydrogen was not thermally desorbed from the films. It is due to the activation of the hydrogen abstraction effects by the increases of the substrate temperatures.