| 摘要 |
A silicon wafer is used as a substrate ( 1 ). A thin layer of metal is deposited and etched to form device metallisation ( 3 ), including electrodes and bondpads. A passivation layer ( 4 ) of silicon nitride is patterned to open access points to the metal. A lower sacrificial layer ( 5 ) is formed from polyimide and is patterned (at 5 (a) and 5 (b)) to open anchor regions for a device and for bridges that will define lateral etch channels for package evacuation. Structural materials that form a MEMS device ( 6 ) and bridges ( 13 ) are then deposited and patterned. The bridges ( 13 ) are patterned simultaneously with the device 6 on the lower sacrificial layer ( 5 ). An upper sacrificial layer ( 7 ) is then deposited over the device ( 6 ) and the lower sacrificial layer ( 5 ) and is patterned to open anchor regions ( 8 ) for an encapsulation layer ( 10 ). Both sacrificial layers are then simultaneously removed in an oxygen plasma ash through lateral etc channels ( 15 ). This step leaves a hollow and empty shell, inside which the MEMS device ( 6 ) is present. The device ( 6 ) is free to move after sacrificial layer removal and has clearance both above and below. The etch channels ( 15 ) are sealed by a sealant ( 40 ) applied over the encapsulant layer.
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