EVALUATION OF INTERNAL-STRESSES PRESENT IN CHEMICAL VAPOR-DEPOSITION DIAMOND FILMS

The internal stresses within diamond films deposited onto silicon substrates by thermal filament chemical vapour deposition (CVD) determined by X-ray diffraction analysis using the sin2-psi method and assuming a biaxial stress state model. The internal stress in thin films arises from intrinsic and thermal stresses. Structural mismatch between the film and substrate and the distribution of defects within the film are responsible for intrinsic stress while thermal stress originates from the difference in the thermal expansion coefficients of the film and the substrate. The contribution of these mechanisms to the internal stress of diamond films is examined and correlated with the microstructure of the films, which was evaluated using Raman spectroscopy and scanning electron microscopy. The microstructure, and therefore internal stresses, of CVD diamond films is a sensitive function of deposition parameters such as temperature and gas composition, which has ramifications for the practical applications of these films.