Abstract: Since the etching mechanism of sacrificial layer is mainly restricted by diffusion,a 2D etching model based on the diffusion equation is constructed and the relative boundary conditions are given.Explicit and implicit numerical algorithms using the finite-difference method are presented to solve the 2D diffusion equation to get the value of the concentration at every site at different times.The topography model is then used to compute the etching state to determine the etch contour at the front.A simulation program that can simulate different complex sacrificial structures is implemented.The simulation is validated by experiments.

Key words: sacrificial layer etching, diffusion equation, difference algorithm