SBIR Phase I: Photolithographic Patterning of Reactive Nano-scale Multilayer Materials for Hermetic Wafer Scale Packaging

This Small Business Innovation Research Phase I project involves a feasibility study of lithographically patterning reactive nanoscale multilayer foils for use in hermetic waferscale packages for MEMS and other electronic devices. A patterned reactive foil sandwiched between two wafers can be ignited and will self-propagate, providing the heat needed for wafer bonding. Because the reaction is very rapid, heat is localized to the vicinity of the foil. Therefore high temperature hermetic bonds confined to the lithographic pattern are obtainable, while temperature sensitive components inside of the sealed package remain unaffected. These foils can also be used to join dissimilar materials with dramatically different thermal expansion coefficients without creating large residual stresses. A typical MEMS device produced today, 80% of the manufacturing cost goes into packaging. Waferscale packaging will dramatically reduce this cost because it leverages knowledge, equipment, and cost models from the semiconductor industry. Features include hermeticity, miniaturization, massively parallel assembly, automated equipment with increased repeatability and yields, and substantial integration of electronic, optical, and mechanical features. Patterning of reactive foils as covered in this proposal will enable wafer bonding that can be generically used for low cost miniaturized packaging of sensing, optical, medical, RF and other MEMS devices.