MEMS gyroscope yield simulation based on Monte Carlo method

MEMS (Micro-Electro-Mechanical Systems) have been used widely in almost all the major industries, while few companies have commercial products in MEMS gyroscope. Besides, there are not many papers on the sensor design, and the papers regarding the packaging for gyroscopes are few, partly due to its highly proprietary nature [1]. The fabrication imperfections are unavoidable during MEMS gyroscope manufacture process. In this paper, Monte Carlo method is used for the simulation of the width of the driving spring defects in vibratory MEMS gyroscope. The yield of MEMS gyroscope is estimated based on the simulation results. For a specific structure of gyroscope, the optimal value of the width of the driving spring to maintain high yield and high performance was found through the yield simulation analysis and structural optimization. There are so many factors that may cause a low yield, and it is critical to determine which factors are most critical. Sensitivity has been analyzed for the driving comb structure by Monte Carlo method. The simulation result shows that gap is the significant factor effecting driving force and the finger tilting angle is the most important factor producing the “redundancy force”, which is undesirable in industry. The two factors must be well designed and processed to improve the yield of the MEMS gyroscope.