GROWTH-RATE STUDIES OF CVD DIAMOND IN AN RF PLASMA TORCH

This paper addresses the complex chemistry in the boundary layer over a substrate in a chemical vapor deposition rector at atmospheric pressure. In this study, a highspeed plasma (140 m/s) was created using a radio-frequency inductively coupled plasma torch for the deposition of diamond thin films. Growth rates on the order of 50 mu m/h were obtained for well-faceted continuous films grown on molybdenum substrates positioned nor mal to the plasma flow. The highest growth rates were obtained at substrate temperatures of 1370 K and a feed gas ratio of 2.5% CH4 in H-2. Growth rates are compared to predicted results obtained from numerical simulations, based on a one-dimensional stagnation-point flow, and are found to be in good agreement. Several other surface analysis techniques were used to characterize the deposited films, including SEM, Raman spectroscopy, transmission electron microscopy, Rutherford backscattering spectroscopy, and hydrogen-forward recoil spectroscopy. Optical emission spectroscopy was used to characterize the RF plasma during the deposition process. Results from these studies form an important database for the validation and improvement of current models of the atmospheric-pressure diamond CVD environment.