A Multiple Internal Seal Ring (MISR) Micro-Electro-Mechanical System
(MEMS) vacuum package that hermetically seals MEMS devices using MISR.
The method bonds a capping plate having metal seal rings to a base plate
having metal seal rings by wafer bonding the capping plate wafer to the
base plate wafer. Bulk electrodes may be used to provide conductive paths
between the seal rings on the base plate and the capping plate. All seals
are made using only metal-to-metal seal rings deposited on the polished
surfaces of the base plate and capping plate wafers. However, multiple
electrical feed-through metal traces are provided by fabricating via
holes through the capping plate for electrical connection from the
outside of the package through the via-holes to the inside of the
package. Each metal seal ring serves the dual purposes of hermetic
sealing and providing the electrical feed-through metal trace.