Three-dimensional Surface-Miacromachining Process Simulations Based On The Narrow Band Level Set Method

The surface micromachining process is an important method of MEMS manufacturing.It can take advantage of the deposition order of different materials on the silicon wafer,and then chooses the appropriate mask information to make various kinds of micro structures.Until now many MEMS devices have the units processed by this process,a simulation system for this process has a great significance for the study of MEMS device fabrication,which can not only shorten the design cycle,reduce the design costs,and also is proof-of-concept.A surface micromachining process simulator based on the narrow band level set method has been researched and developed.The software system can realize the analysis of the standard layout CIF format file and save the results.Combining the processing flow and setting the relevant etching and deposition parameters,the 3-D simulation of the surface micromachining process is realized based on the narrowband level set algorithm.The results reproduce the manufacturing process of MEMS devices.The system provides four modules,the parameters control module:including the time,rate,geometric parameters of the mask,and could be changed according to different processes;The mask loading module:lode the CIF file exported from the L-Edit,then analysis the CIF file and translate it into the TXT files which could be read in the next steps.The simulation module:simulate according to the process and the specific mask information.The exposure module:to visualize the simulation results which developers could base on to modify the model.Finally by comparing with the scanning electron microscopy(SEM)pictures,the simulation system was certificated to be accuracy.Firstly,this paper briefly introduces the surface micromachining process and MEMS CAD technology.And then the analysis flow of the CIF mask information is introduced.The etching and deposition techniques in the surface micromachining process,as well as the geometrical models of etching and deposition applied in the simulation,are presented.The process simulation algorithm is introduced in detail,and the principle and implementation method of the narrow band level set are introduced emphatically.Finally,the comparison among the CIF files,simulation results and the SEM photograph of different structures are presented.In this paper,the C ++ Builder software is used to compute the simulation software.The etching and deposition process select a simple geometric model which based on the narrowband level set algorithm to advance the surface.Connecting with the CIF mask information,a serious of simulations have been designed and performed using this simulation system,and by the comparison between the results and SEM photograph,the simulation system is demonstrated to be accuracy and the efficiency.