Abstract
This paper presents a chip-level integration of radio-frequency (RF) microelectromechanical systems (MEMS) air-suspended circular spiral on-chip inductors onto MOSIS RF circuit chips of LNA and VCO using a multi-layer UV-LIGA technique including SU-8 UV lithography and copper electroplating. A high frequency simulation package, HFSS, was used to determine the layout of MEMS on-chip inductors with inductance values close to the target inductance values required for the RF circuit chips within the range of 10%. All MEMS on-chip inductors were successfully fabricated using a contrast enhancement method for 50 μm air suspension without any physical deformations. High frequency measurement and modeling of the integrated inductors revealed relatively high quality factors over 10 and self-resonant frequencies more than 15 GHz for a 1.44 nH source inductor and a 3.14 nH drain inductor on low resistivity silicon substrates (0.014 Ω cm). The post-IC integration of RF MEMS on-chip inductors onto RF circuit chips at a chip scale using a multi-layer UV-LIGA technique along with high frequency measurement and modeling demonstrated in this work will open up new avenues with the wider integration feasibility of MEMS on-chip inductors in RF applications for cost-effective prototype applications in small laboratories and businesses.
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Acknowledgments
This work was supported in part by the National Science Foundation under the grant ECS-0296108. The authors would like to thank PVA TePla for equipment support (TePla 300 microwave plasma etch system). The supports of UTD clean room staffs and UTD Micro/Nano Devices and Systems Laboratory are acknowledged.
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Park, D.SW., Jeong, Y., Lee, JB. et al. Chip-level integration of RF MEMS on-chip inductors using UV-LIGA technique. Microsyst Technol 14, 1429–1438 (2008). https://doi.org/10.1007/s00542-007-0532-9
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DOI: https://doi.org/10.1007/s00542-007-0532-9