Low-Cost Microfabrication for MEMS Switches and Varactors

This paper presents a low-cost micro-fabrication technique for manufacturing RF MEMS switches and varactors without intensive cleanroom environments. The fabrication process entails only laser micro-structuring technique, noncleanroom micro-lithography, standard wet-bench and hot-film emboss of SU-8 and ADEX polymers. MEMS movable structures were fabricated out of 14-μm-thick Aluminum foils and suspended above coplanar-waveguide transmission lines, which were implemented on top Duroid substrates, via 5-μm-thick SU-8 dielectric anchors. Both MEMS structures and Duroid substrate were integrated using micro-patterned polymers, developed by using dry-film ADEX and SU-8 polymers, for a composite assembly. An average fabrication yield of higher than 60% was achieved, calculated from ten fabrication attempts. The RF measurement results show that the RF MEMS devices fabricated by using the novel micro-fabrication process have good figure-of-merits, at much lower overall fabrication costs, as compared to the devices fabricated by conventional cleanroom process, enabling it as a very good micro-fabrication process for cost-effective rapid prototyping of MEMS.