Effect of Filament Temperature on in Situ Absorption Spectrum and Diamond Film Growth

In situ infrared absorption spectroscopy has been used to study chemical vapor deposition (CVD) diamond growth process. The effects of filament temperature on in situ infrared absorption and diamond film growth are investigated. We find that the absorption of CH4 radicals is always exist while that of C2H2 can only be detected at filament temperatures higher than a threshold value, 1 700 ℃. High filament temperature results in more C2H2 formation and CH4 decomposition. At the same time, diamond films prepared at high filament temperature will have a higher diamond content and growth rate. We conclude that more decomposition in CH4 will lead to high concentration C2H2 and hydrocarbon formation radicals which may benefit the high quality diamond film growth and promote growth rate.