DIAMOND GROWTH BY HOT-FILAMENT CHEMICAL-VAPOR-DEPOSITION - STATE-OF-THE-ART

Low-pressure diamond deposition using hot-filament gas activation was the first method to achieve nucleation and continuous diamond growth on various substrates. The method itself is simple but the strongly interdependent parameters involved must be strictly controlled in order to obtain reproducible diamond quality. The material used for the hot filament and its reactions during diamond deposition are important for gas activation. Together with this the chemical stability of the substrate and the deposition parameters determine the quality of the diamond layers produced. The growth conditions must be optimized for each specific application. When scaling up the hot-filament method, a uniform temperature distribution and the gas flow become additional factors of major importance for obtaining good quality diamond coating. The C: 0: H ratio in the reaction gas also influences diamond growth rates and the resulting quality of the diamond films.