Effect of fabrication imperfections on energy loss through mechanical mode coupling in MEMS

We identified the mechanical mode coupling as a major energy loss mechanism limiting the quality factor of MEMS resonators, such as gyroscopes. An analytical model was derived to quantify the effect of fabrication imperfections on the phenomenon of intermode energy exchange. Using both finite element analysis and analytical modeling, the mechanical coupling between in-plane and out-of-plane modes of resonators with fabrication imperfections was studied and the decrement in the quality factor due to mode coupling was predicted. The analysis was used to explain why some low frequency designs are exhibiting a quality factor close to their fundamental TED limit, while others are showing the quality factor with orders of magnitude lower than their TED limit. Our analytical predictions are supported experimentally.