DocumentCode :
759969
Title :
High-Q single crystal silicon HARPSS capacitive beam resonators with self-aligned sub-100-nm transduction gaps
Author :
Pourkamali, Siavash ; Hashimura, Akinori ; Abdolvand, Reza ; Ho, Gavin K. ; Erbil, Ahmet ; Ayazi, Farrokh
Author_Institution :
Sch. of Electr. & Comput. Eng., Georgia Inst. of Technol., Atlanta, GA, USA
Volume :
12
Issue :
4
fYear :
2003
Firstpage :
487
Lastpage :
496
Abstract :
This paper reports on the fabrication and characterization of high-quality factor (Q) single crystal silicon (SCS) in-plane capacitive beam resonators with sub-100 nm to submicron transduction gaps using the HARPSS process. The resonating element is made of single crystal silicon while the drive and sense electrodes are made of trench-refilled polysilicon, yielding an all-silicon capacitive microresonator. The fabricated SCS resonators are 20-40 μm thick and have self-aligned capacitive gaps. Vertical gaps as small as 80 nm in between 20 μm thick silicon structures have been demonstrated in this work. A large number of clamped-free and clamped-clamped beam resonators were fabricated. Quality factors as high as 177000 for a 19 kHz clamped-free beam and 74000 for an 80 kHz clamped-clamped beam were measured under 1 mtorr vacuum. Clamped-clamped beam resonators were operated at their higher resonance modes (up to the fifth mode); a resonance frequency of 12 MHz was observed for the fifth mode of a clamped-clamped beam with the fundamental mode frequency of 0.91 MHz. Electrostatic tuning characteristics of the resonators have been measured and compared to the theoretical values. The measured Q values of the clamped-clamped beam resonators are within 20% of the fundamental thermoelastic damping limits (QTED) obtained from finite element analysis.
Keywords :
Q-factor; elemental semiconductors; micromachining; micromechanical resonators; microsensors; silicon; tuning; 0.91 MHz; 12 MHz; 19 kHz; 20 to 40 micron; 80 kHz; 80 nm; HARPSS capacitive beam resonators; HARPSS process; Si; capacitive microresonator; clamped-clamped beam resonators; clamped-free beam resonators; drive electrodes; electrostatic tuning characteristics; fabrication; high aspect ratio; high-Q single crystal Si resonators; high-quality factor resonators; loss mechanisms; self-aligned capacitive gaps; self-aligned transduction gaps; sense electrodes; trench-refilled polysilicon; Electrodes; Electrostatic measurements; Fabrication; Microcavities; Q factor; Q measurement; Resonance; Resonant frequency; Silicon; Tuning;
fLanguage :
English
Journal_Title :
Microelectromechanical Systems, Journal of
Publisher :
ieee
ISSN :
1057-7157
Type :
jour
DOI :
10.1109/JMEMS.2003.811726
Filename :
1219517
Link To Document :
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