In order to investigate the effects of argon and oxygen on diamond synthesis, the behaviors of diamond deposition using microwave plasma chemical vapor deposition method have been studied by varying the concentration of argon and oxygen in the methane - hydrogen gas mixture. Diamond films are deposited on silicon wafer at the condition of substrate temperatures ; 800 - 900℃, total reaction pressures ; 40 torr and methane concentration ; 0.5% - 5.0% and they are characterized by scanning electron microscopy, Raman spectroscopy and optical emission spectroscopy.
Enhanced deposition rates have been observed by adding argon into the methane - hydrogen system but nondiamond carbon phases in the films have increased. As oxygen is added, the quality of deposited diamond films has been improved. Small oxygen additions along with argon can effectively suppress the formation of nondiamond carbon components and increase the deposition rates of diamond films.