Design considerations for large MEMS

There has been an increasing need for the design and fabrication of large (few millimeters) MEMS made of micron-size features for a variety of applications. Mechanical design of large MEMS structures needs careful consideration of the forces developed during and after processing to ensure their survivability and reliable performance. forces generated to actuate a device, e.g., capacitive force, are well characterized. However, the forces developed due to conditions of processing, such as fluid forces, have not yet been fully characterized. In this paper, we propose simple models to estimate thermal and intrinsic stresses and the corresponding deformations of large MEMS, as well as fluid forces during wet processing. We also discuss the issue of stability of large MEMS during actuation.