Li-Wen Hung
Department of Electrical Engineering and Computer Sciences, UC Berkeley
BSAC Researcher, Disseration Presentation
April 6, 2011 | 02:00 to 03:00 | 400 Cory Hall, Hughes Room
Host: Clark Nguyen
With an increased need for regional and global roaming and continuous advances in wireless communication standards, future transceivers need to support multi-mode operation without increasing in cost, hardware complexity, and power consumption. Channel-selection filters offer a solution for more simplified and versatile transceivers. Such channel-selection filters, however, impose requirements on the constituent resonators that is not yet achievable. Specifically, electrostatic resonators achieve high Q but suffer from high impedance, while piezoelectric resonators offer low impedance without sufficient Q. The goal of the presented research was to address the issues of both technologies. Sub-30nm gap spacing enables electrostatic resonators to achieve acceptably low impedance; however, small gaps are difficult to release. Two methods will be discussed for forming sub-30nm gaps: partially-filling gaps with high-k dielectric and generating gaps via volume reduction of silicidation. The latter does not require any etching and can find wide applications ranging from electronics to vacuum packaging. Then, methods for improving Q's of piezoelectric AlN resonators by up to 9 times will be discussed: capacitive-piezo transducers and Q-boosting mechanical composite-array. Both methods achieve Q exceeding 10,000, posting the highest reported Q for resonators made of sputtered AlN and confirming that AlN is indeed a high-Q material. The talk will conclude with the impact of this research and the outlook for future research.
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