Wafer Scale Encapsulation of Large Lateral Deflection MEMS Structures

Packaging of microelectromechanical systems (MEMS) is a critical step in the transition from product development to production. This paper presents a robust, hermetically-sealed encapsulation method that can accommodate many traditional MEMS devices by allowing large lateral deflection structures within a clean environment. Using the new technology described in this paper, trench widths ranging from 1 mum to 100 mum were successfully encapsulated at the wafer level while maintaining devices as thick as 20 mum. Devices produced with this method have proven durable enough to withstand harsh post-processing such as dicing and wire bonding. Two different types of MEMS resonators are also discussed, demonstrating the use of both large and small trench widths within the encapsulation.