ORIGINS OF THE RESIDUAL-STRESS IN CVD DIAMOND FILMS

Diamond films were deposited on (100) Si wafer, WC (5%Co) and quartz s ubstrate materials by a microwave plasma chemical vapor deposition (CV D) system. The effects of deposition and substrate conditions on resid ual stress of the films were systematically investigated The films wer e characterized by scanning electron microscopy, X-ray diffraction, Ra man and indentation adhesion testing. The him structure including its non-diamond carbon content, crystal size, texture coefficient, film th ickness and surface roughness were examined. The results show that the residual stress of the films is a function of the surface pretreatmen t, in addition to the substrate material and deposition conditions. Th e origins of the residual stress are mainly the thermal stress and the intrinsic stress. The intrinsic stress is mainly from the effect of t he non-diamond carbon content in the diamond crystals, not at the crys tal boundaries. A greater non-diamond carbon content in diamond crysta ls results in a greater residual stress. The texture of the films has no significant effect on the residual stress. A low compressive residu al stress on Si wafer is beneficial to the adhesion of the film.