Theoretical and experimental studies of flip-chip assembled high-Q suspended MEMS inductors

Jun Zeng, Changhai Wang, Alan J. Sangster

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


This paper reports the theoretical and experimental studies of high-Q suspended microinductors produced by flip-chip assembly for multigigahertz RF integrated-circuit applications. The effects of device and substrate parameters on the Q factor of the inductor devices are studied by numerical simulation using Ansoft's High Frequency Structure Simulator electromagnetic field simulation package. Suspended inductor devices are realized using a flip-chip assembly method in which the inductor structures with the supporting pillars are fabricated on a low-cost polyimide thin-film carrier and then assembled onto a low resistivity (3-4 O · cm) silicon substrate by flip-chip bonding. Individual and 2 × 2 arrays of meander and spiral inductor designs have been successfully fabricated with air gap heights ranging from 15 to 31 µm. Maximum Q factors of ~15 and ~13 at ~1 GHz have been achieved for meander and spiral suspended inductor devices before pad deembedding. It is shown that the optimal air gap between the inductor and substrate surface is ~15 µm beyond which no further enhancement in the Q factor can be obtained for devices on low-resistivity substrates. The experimental results are in excellent agreement with that of theoretical simulation. The inductor assembly method requires minimal chip/wafer processing for integration of high-Q inductors. © 2007 IEEE.

Original languageEnglish
Pages (from-to)1171-1181
Number of pages11
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number6
Publication statusPublished - Jun 2007


  • Flip-chip assembly
  • High Q
  • Microelectromechanical systems (MEMS)
  • Modeling
  • Passive inductor
  • Polyimide film
  • Silicon RF integrated circuit (RFIC)


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