Study on stress and strain of cubic boron nitride thin films

The stress and strain in c-BN films deposited onto silicon substrate by hot filament assisted rf plasma chemical vapor deposition is determined by XRD analysis using the sin(2)psi method and assuming an effective stress model. The compressive stress in c-BN is much greater than that in h-BN for the same film, when both c-BN and h-BN in the same film have similar amount of elastic strain. To investigate the validity of the effective stress model, the stress in the films was measured with a surface profilometer also. Residual stresses in the films were compressive and varied from 2.87 GPa to 12.1 GPa with increase in substrate temperature (700-1200 degrees C). The dependence of the compressive film stress on c-BN content is also given in the present work. The increase of compressive film stress with increasing c-BN content is due to the elastic modulus of c-BN being greater than that of h-BN. (C) 1998 Elsevier Science S.A.