General MEMS Process Physics Simulation and its Applications

Commercial CAD tools for MEMS have significantly contributed to the growth that the MEMS industry has experienced over the past two years by reducing development cycles and enabling the more rapid release of mature MEMS products. Unfortunately, the CAD for MEMS industry has focused primarily on device performance (for example, mechanical response due to electrostatic loading), with a concentration on testing and optimizing the performance in a workstation environment. Device manufacturability issues have been neglected and considered secondary design criteria. Understanding device fabrication is essential in determining if an optimized device design can be realized in a cost-effective manner using current microfabrication equipment. Research has been undertaken to identify key process steps in MEMS fabrication that can play a role in device behavior. The release of commercial anisotropic etch simulation code has proven the utility of process simulation. IntelliSense has developed a general MEMS process physics simulation capability that addresses key process steps in both surface and bulk MEMS fabrication. Process simulation modules developed include: thin film deposition; wet and dry etching; bonding; micro-assembly; doping; electroplating; and liftoff. These processes are simulated both physically and semi-empirically. As a result, the geometric shape, incorporating both the material properties and the process induced effects, is efficiently generated and transitioned to a multi-physics analysis module or system level analysis gateway. Accounting for process-induced effects when simulating the performance of device designs allows for greater accuracy, which in turn helps reduce product development times beyond the capabilities of current CAD tools for MEMS.