This process is well suited for structures fabricated on dissimilar substrates.
A process for transferring an entire wafer-level micromachined silicon structure for mating with and bonding to another such structure has been devised. This process is intended especially for use in wafer-level integration of microelectro- mechanical systems (MEMS) that have been fabricated on dissimilar substrates.
Unlike in some older membrane-transfer processes, there is no use of wax or epoxy during transfer. In this process, the substrate of a wafer-level structure to be transferred serves as a carrier, and is etched away once the transfer has been completed. Another important feature of this process is that two wafer-level structures to be integrated with each other are indium-bump-bonded together; this is advantageous in that it produces less (in comparison with other bonding techniques) stress during bonding of structures formed on two dissimilar wafers. Moreover, unlike in some older membrane-transfer processes, there is no incidental release of HF from the final structure — an advantage when indium, aluminum, or another soft metal is used for bonding.
This work was done by Eui-Hyeok Yang and Dean Wiberg of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Manufacturing category.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to
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Refer to NPO-21088, volume and number of this NASA Tech Briefs issue, and the page number.
This Brief includes a Technical Support Package (TSP).
Wafer-Level Membrane-Transfer Process for Fabricating MEMS (reference NPO-21088) is currently available for download from the TSP library.
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