Study And Simulation Of Amended 2-D Model Of Sacrificial Layer Etching

Sacrificial layer etching is one of the key technology in the Microelectromechanical Systems(MEMS) manufacturing process,finally film on cavity or other suspended element is obtained after the sacrificial layer is released.It is widely used in MEMS devices, and highly affected to the MEMS devices.In order to shorten the research cycle and cost savings, Computer aided design(CAD) is becoming more and more important,and the research of the simulation of the process sacrificial layer etching has great significance in the manufacture of MEMS devices.According to the etching chemical mechanism of HF etching oxidation silicon(SiO2),many etch models are founded,and most of them are in one-dimension space.On the basis of Liu. and Monk.’s model, Eaton establishes 2-D radial coordinate model to simulate the structure of bubble and the combined structure of port,concentric and bubble. On the basis of Liu.’s model, Li Wen extendes the 1-D simulation to 2-D,and achieve the simulation of bubble of single open.But these simulation are all short of universality,and old models regard the diffusion coefficient as a coefficient for convenience,which causes simulation error.This paper focuses on the research of 2-D planimetric rectangular coordinate etching model, and amends the diffusion coefficient. The amended 2-D etching model is obtained by considering the diffusion coefficient as a function of etchant concentration. The numerical algorithm of finitedifference method is given for the diffusion equation.Then the Topography Model is used to compute the etching state to determine the etch contour at the front. The simulation program that can simulate the different and complex sacrificial structures is implemented. Language C is used to simulate the etching process, and Matlab is used to graphing.To validate the simulation, setup parameters on the basis of related papers’ test process.Then The simulation results are consistent to the experimental results in etching shape and etching size through comparing, and its etching size error can be restricted to 10% basically which is reduced compared with the model before amending. Therefore,the simulation veracity is validated.