An integrated process for post-packaging release and vacuum sealing of electroplated nickel packages

This paper presents a packaging technology that employs a thick nickel film to vacuum seal a MEMS structure at the wafer level. The package is fabricated in a 3-mask process by electroplating a 40-micron thick nickel film over an 8-micron sacrificial photoresist that is removed prior to package sealing. The large fluidic access port enables an 800/spl times/800 /spl mu/m package to be released in less than three hours. Implementation of electrical feedthroughs in this process requires no planarization. Device release is performed after the formation of the first level package. Several mechanisms, based upon localized melting and Pb/Sn solder bumping, for sealing low fluidic resistance feedthroughs have been investigated. This package has been fabricated with an integrated Pirani gauge to further characterize the different sealing technologies. These gauges have been used to establish the hermeticity of the different sealing technologies and have measured a sealing pressure of /spl sim/1.5Torr.