Method For Sealing And Backside Releasing Of Microelectromechanical Systems

Abstract

Disclosed are methods for fabricating encapsulated microelectromechanical systems (MEMS) devices. A MEMS device fabricated on a CMOS wafer is encapsulated using an etch resistant thin film layer prior to the release of the MEMS device. Once CMOS processing is completed, the wafer is etched to release the MEMS device. If the MEMS is fabricated on a silicon-on-insulator (SOI) wafer, the buried oxide of the SOI wafer acts as an etch stop for the etching. A sacrificial layer(s) is accessed and removed from the back side of the wafer, while the front side of the wafer is protected by a masking layer. The MEMS device is released without having any detrimental effects on CMOS components. If desired, the wafer can be mounted on another substrate to provide hermetic or semi-hermetic sealing of the device.