| Residual stresses present in diamond films produced by the CVD process often cause cracking and bowing of films, and then degrade product quality. To discuss the causes of bowing and cracking, the measurement and mechanical analyses of residual stresses are very important in diamond film research. Of the residual stresses, the intrinsic stress is one of the most important research topics because its effect on bowing of a free standing diamond film is strong even for its small magnitude. Quantification of the intrinsic stress is limited because high-temperature plastic deformation of Si substrate enlarges the substrate bending. In this study, an analytical model is proposed to obtain the initial intrinsic stress without contribution of the plastic deformation of the substrate. This new model in which the plastic deformation of Si is considered was developed using elastoplastic beam theory and diamond etching technology. In the model, the plastic deformation of Si is given by plastic curvature of substrate measured after removing the diamond film. The experiment is performed on diamond films deposited by microwave plasma assisted CVD. The results show that the overestimated intrinsic stress can be compensated successfully through the new model, which is consistent with that by Raman spectroscopy. The effects of film thickness and deposition temperature on residual stress is discussed in terms of microstructural change of diamond film. |
|
