Flip-chip assembly for Si-based RF MEMS

MEMS-based RF components are being developed for variuos microwave and millimeter-wave applications. However, most RF MEMS have to be fabricated using GaAs, ceramics, high-resistivity silicon or other RF-compatible materials; such fabrication techniques are not commonly used by mainstream silicon-based MEMS manufacturing infrastructure. As a result, the complexity of these MEMS is limited. Using flip-chip assembly and silicon removal techniques, there is an opportunity to integrate MEMS onto any RF compatible substrate without the silicon semiconductor effects. Thus, it is possible to manufacture complex MEMS cost-effectively for a new generation of RF MEMS with superior functionality, e.g. tunable capacitors, multi-way switches and arrays of hundreds of these or other RF components. This new technology is described with an emphasis on four issues: warpage, actuators, release and flip-chip bonding.