Deformation analysis of tunable Fabry-Perot structure caused by thermal residual gradient stresses

The deformation of Fabry-Perot caused by thermal residual stresses is investigated. The sizes of structure have effect on deformation, especially the ratio of width to length, W/L. If the W/L ratio is smaller, the deformation is larger. But, the structure could be still considered as flat surface. It only tilts an angle. However, when depositing a material on the structure layer, the structure would no more flat for the mismatch of thermal expansion coefficients inducing larger thermal residual gradient. The results show the structure with larger W/L ratio will be more flat. If the W/L ratio is less than one, the structure is deformed and has less flat part. Even the warpage could happen.