Synthesis surface effects on the stress and deformation of film/substrate system

The closed-form solutions of bending curvature and stress distribution in film/substrate system with the synthesis surface effect are proposed by minimizing the total potential energy. Effects of the roughness and the residual surface stress on stress in film are addressed. Results reveal that, at a given thickness of the substrate, effects of roughness and residual surface stress on the bending curvature become significant with decreasing the film thickness. The roughing surface will enlarge the magnitudes of bending curvature and film stress. The direction change of residual surface stresses can lead to a reversed bending of film/substrate system.

- At nanoscale, the roughened surface effects on stress and deformation become considerable with increasing the surface-to-bulk ratio.
- A general theoretical model is developed for the bending curvature and residual stress of film/substrate structure with the roughened surface effects.
- With decreasing the thickness of film, the synthesis surface effect may switch the direction of stress and deformation.