Flip-chip bonded MEMS capacitor Applied on tuning superconductive resonator

This paper presents the design methodology, fabrication and characterization of flip-chip bonded MEMS capacitor for tuning high temperature superconductive resonator. Because the main issue of MEMS capacitor integrated with high temperature superconductor (HTS) is high driving voltage due to accumulated thermal stress, a methodology to decrease the thermal stress is discussed. In this work, the thermal stress can be reduced to several MPa, and driving voltage is about 40 V. To avoid degradation of HTS thin film during MEMS process, MEMS capacitor is fabricated separately and then flip-chip bonded on the HTS resonator. The tuning effects of this MEMS capacitor applied on HTS resonator of 3 GHz resonant frequency are presented.