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Summary: THIN-FILM PIEZOELECTRIC-ON-SUBSTRATE RESONATORS WITH Q
ENHANCEMENT AND TCF REDUCTION
Wanling Pan and Farrokh Ayazi
Georgia Institute of Technology, Atlanta, GA, USA
E-mail: wanling@ieee.org
ABSTRACT
In this paper we report on lateral mode thin-film
piezoelectric-on-substrate (TPoS) resonators with
techniques to enhance the quality factor (Q) and
reduce the temperature coefficient of frequency
(TCF). Such techniques utilize a highly or
degenerately doped Si substrate layer as the ground
electrode, and reduce the thickness and volume
ratio between the AlN piezoelectric layer and the Si
substrate. By patterning the AlN and eliminating
the bottom metal electrode, a record quality factor
of over 30,000 is observed in air at 27MHz
(>66,000 in vacuum). The highly-doped Si brings
the resonator average TCF to around 12ppm/°C.
INTRODUCTION
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