Effect of Diamond Films Thickness on Thermal Residual Stress

Each component of thermal residual stress in diamond films deposited onto Mo substrate was simulated and analyzed comprehensively by using the finite element method, and the different thickness (20~1 000 m) of the films was used during the simulation. The contour plots of these components distribution were obtained. In addition, the effect of the films thickness on the maximum tensile principal stress in films and on the maximum of every stress component at interface between films and substrate was investigated. The results show that the location of maximum tensile principal stress in the films is at the upward face or side face of the films or the interface, and the magnitude of it increases when the films become thicker. Also, the maximum axial stress at the interface increases when the films become thicker whereas the maximum compressive radial stress, maximum compressive circular stress and maximum shear stress at the interface are in reverse, and the reduction extent of the maximum shear stress is small. The increase or reduction rate of each stress mentioned above is slower when the films thickness becomes larger. These conclusions are useful to choose rationally films thickness and to control effectively the stresses during preparation of diamond films.