A new self-sealing thin-film encapsulation process for MEMS

In this paper we present a new sealing technique for thin-film encapsulation of MEMS components without unwanted deposition on the device surface. The capping layer contains an array of bimorph cantilevers placed on top of the access holes acting as thermally-actuated valves that close the access holes during the sealing step. Microcavities were designed and fabricated to validate the concept. Both high and low-temperature encapsulation schemes have been implemented. Bimorph cantilevers made of LPCVD SiO and SiN are used for the high temperature micropackages whereas PECVD SiN and Aluminum are used for low temperature micropackages. The micropackages are successful encapsulated and no deposition is observed inside the micropackages.