A low cost wafer-level MEMS packaging technology

This paper presents a low-cost low-temperature packaging technique for wafer-level encapsulation of MEMS devices fabricated on any arbitrary substrate. The packaging process presented here does not involve wafer bonding and can be applied to a wide variety of MEMS devices after their fabrication sequence is completed. Our technique utilizes thermal decomposition of a sacrificial polymeric material through a polymer overcoat cap, and can be applied to both surface and bulk micromachined structures. Encapsulation of high-g silicon-on-insulator resonators, and thick silicon gyroscopes and accelerometers are presented.