Growth of diamond films on Si 3 N 4 coated silicon substrates

Polycrystalline diamond films were deposited on to Si₃N₄ coated silicon substrates using thermal chemical vapour deposition. The defects on the amorphous Si₃N₄ layer played an essential role in diamond nucleation. After deposition, very few diamond crystallites were found on the untreated Si₃N₄ coating, while a diamond film had formed on the ultrasonic diamond powder treated Si₃N₄ coating. During the deposition process, the substrate temperature drastically affected the integrity of the intermediate Si₃N₄ layer. At a substrate temperature above 850°C, the Si₃N₄ layer began to degrade. The lower CH₄ concentration produced better diamond films in terms of crystallinity and purity. The adhesion of the diamond film to the Si₃N₄ coated silicon substrate and the friction coefficient between the diamond stylus and the diamond film decreased as the CH₄ concentration increased. The corrosion resistance of the diamond film on the Si₃N₄ coated silicon substrate was much stronger than that of the Si₃N₄ film on the silicon substrate.

MST/3177