DocumentCode :
1951117
Title :
Radial extensional mode AlN-film resonator with high coupling factor
Author :
Isobe, A. ; Asai, K.
Author_Institution :
Central Res. Lab., Hitachi, Ltd., Kokubunji, Japan
fYear :
2010
fDate :
11-14 Oct. 2010
Firstpage :
1277
Lastpage :
1280
Abstract :
There is strong demand for MHz-band resonators integrated in IC chips. Although AlN-film resonators, such as FBARs, have good compatibility with CMOS fabrication, it is difficult to produce low-frequency devices because the vibration mode is thickness extension. It has recently been reported that a disc-type AIN-film resonator can excite radial extensional (RE) modes strongly [6]. In this study, the electrical characteristics of the fundamental RE mode were focused on, and the relation between the Q value and the structure of the resonator was investigated. Because the RE resonator, such as a disc-type resonator, had a null point at the center of the resonant part, it was difficult to connect an electric lead line at the null point using conventional AIN-film fabrication processes. We adopted a tuning-fork-type structure, which consisted of two RE resonant parts, a connecting part, and two supporting beams. Because the tuning-fork-type resonator had a null point at the center of the connecting part between the RE resonant parts, it was easy to connect the supporting beams, which acted as the electric lead lines too, at the null point. A fabricated RE resonator exhibited a high coupling factor of 2.8% and a high Q value of 3000 at the series resonant frequency and 4000 at the parallel resonant frequency. The figure of merit was 71 at the series resonant frequency and 94 at the parallel resonant frequency. These are the highest values for contour-mode AIN resonators so far reported and indicate that the RE resonator integrated in an IC chip is suitable for oscillator and filter applications.
Keywords :
CMOS integrated circuits; aluminium compounds; microstrip resonators; AlN; CMOS fabrication; MHz band resonators; disc type resonator; electric lead line; electrical characteristics; film resonator; high coupling factor; integrated chips; low frequency devices; parallel resonant frequency; radial extensional mode; series resonant frequency; thickness extension; tuning fork type resonator; vibration mode; Couplings; Electrodes; Films; Oscillators; Resonant frequency; Substrates; Vibrations; AlN; Q value; coupling factor; radial extensional mode; resonator;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Ultrasonics Symposium (IUS), 2010 IEEE
Conference_Location :
San Diego, CA
ISSN :
1948-5719
Print_ISBN :
978-1-4577-0382-9
Type :
conf
DOI :
10.1109/ULTSYM.2010.5935436
Filename :
5935436
Link To Document :
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