Calibration of Wet Etching Parameters for Sacrifice Layer of MEMS

This paper presents a wet etching simulation method for sacrifice layer of MEMS (micro electro mechanical system) that considers physical phenomenon including flow, diffusion and chemical reaction. In this method, a partial differential equation with implicit parameterization of etching properties was studied that was solvable by any commercial CFD code. Two parameters for flow and reaction were determined by fitting the numerical result to experimental one obtained using a test device. For automatic calibration of parameters, an error function was proposed considering the position of etching front, averaged etching rate and shape of etching front. The distribution of the error (response surface) was predicted by second order Lagrange interpolation. The iteration algorithm for this automatic calibration contributed to reduce the computational cost. Once the parameters were determined, the etching simulation of real MEMS device could be practically carried out.