Microencapsulation Construction – After the switches are constructed, the process steps to produce a wafer-level micro-encapsulation of RF MEMS switches are as follows:
Use a sacrificial layer to form a temporary encapsulation above and around the unreleased membrane.
Deposit an insulator to form a structural shell.
Pattern and etch the insulator to form a cage-like structure on top of the sacrificial layer.
Plasma ash the photoresist to create a microcavity structure and also release the membrane. Once the sacrificial layer is removed, there is in place a cage-like structure, separated by a gap, over the released membrane.
Apply a liquid encapsulant, such as benzocylcobutene (BCB), to the entire wafer. The surface tension of the encapsulant ensures the cage structure is covered without wicking through the holes to encroach onto the switch.
Cure the encapsulant to create a closed seal over the microcavity. This step can go up to 250°C since all sacrificial layers have been removed.
Apply optional sealant overcoats (such as parylene) for additional protection.
Nombre: Lenny D. Ramirez C.
Ver blogg: http://lennyramirez-crf.blogspot.com/
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