TY - GEN
T1 - Micromachined sapphire GHz lateral overtone bulk acoustic resonators transduced by aluminum nitride
AU - Kuo, Nai Kuei
AU - Gong, Songbin
AU - Hartman, Jeffrey
AU - Kelliher, James
AU - Miller, Wayne
AU - Parke, Justin
AU - Krishaswamy, Silai V.
AU - Adam, John D.
AU - Piazza, Gianluca
PY - 2012
Y1 - 2012
N2 - This paper introduces a new class of piezoelectric-transduced bulk acoustic wave resonators formed by a micro-machined c-plane sapphire (Al 2O 3) membrane (∼ 750 nm). The thin film sapphire (TFS) is fully suspended in air and made to vibrate in the GHz range by a sputtered aluminum nitride (AlN) film. For the first time, the realization of the TFS is achieved via a layer transfer process from a single crystal c-plane sapphire wafer. In order to demonstrate the superior intrinsic material quality of the sapphire membrane, a lateral overtone bulk acoustic resonator (LOBAR) configuration, recently introduced by our group, was employed. The LOBAR is engineered to minimize the effects of mechanical energy dissipation and extract the ultimate limit set by phonon-phonon dissipation in the TFS. In addition to the conventional rectangular design, an annular LOBAR geometry is introduced in this paper. This design permits to lower the device impedance (∼3k Ω), while attaining a high quality factor (Q). The measured responses exhibit f·Q of 4.1·10 12 Hz and 4.6·10 12 Hz at 1 and 2 GHz, respectively in the annular configuration with a 9% of transducer to sapphire coverage ratio. The conventional rectangular LOBAR with coverage ratio of 0.57% exhibits a Q of 5,440 at 2.8 GHz, which translates to the highest f·Q (1.53·10 13 Hz) ever reported for AlN-based suspended resonators.
AB - This paper introduces a new class of piezoelectric-transduced bulk acoustic wave resonators formed by a micro-machined c-plane sapphire (Al 2O 3) membrane (∼ 750 nm). The thin film sapphire (TFS) is fully suspended in air and made to vibrate in the GHz range by a sputtered aluminum nitride (AlN) film. For the first time, the realization of the TFS is achieved via a layer transfer process from a single crystal c-plane sapphire wafer. In order to demonstrate the superior intrinsic material quality of the sapphire membrane, a lateral overtone bulk acoustic resonator (LOBAR) configuration, recently introduced by our group, was employed. The LOBAR is engineered to minimize the effects of mechanical energy dissipation and extract the ultimate limit set by phonon-phonon dissipation in the TFS. In addition to the conventional rectangular design, an annular LOBAR geometry is introduced in this paper. This design permits to lower the device impedance (∼3k Ω), while attaining a high quality factor (Q). The measured responses exhibit f·Q of 4.1·10 12 Hz and 4.6·10 12 Hz at 1 and 2 GHz, respectively in the annular configuration with a 9% of transducer to sapphire coverage ratio. The conventional rectangular LOBAR with coverage ratio of 0.57% exhibits a Q of 5,440 at 2.8 GHz, which translates to the highest f·Q (1.53·10 13 Hz) ever reported for AlN-based suspended resonators.
UR - http://www.scopus.com/inward/record.url?scp=84860457113&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84860457113&partnerID=8YFLogxK
U2 - 10.1109/MEMSYS.2012.6170085
DO - 10.1109/MEMSYS.2012.6170085
M3 - Conference contribution
AN - SCOPUS:84860457113
SN - 9781467303248
T3 - Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)
SP - 27
EP - 30
BT - 2012 IEEE 25th International Conference on Micro Electro Mechanical Systems, MEMS 2012
T2 - 2012 IEEE 25th International Conference on Micro Electro Mechanical Systems, MEMS 2012
Y2 - 29 January 2012 through 2 February 2012
ER -