A new micro-rotating structure

This paper presents a new micro-rotating structure for the local measurement of residual strain in thin films. Compared with a conventional rotating structure, the new structure doesn't have a rotating point, but has lower residual strain distribution after deformation, a more precise test model, and larger measurement range. An analytical expression to calculate the residual strain is given so that the residual strain can be easily evaluated from the deflection of the rotating beam. Finite-element method (FEM) was also used both to optimize the design and to calibrate the new structure. Residual strains in LPCVD polysilicon films were determined by the new structure and compared with measurements by the conventional rotating structure. The two methods lead to comparable results.