Micromachined sapphire GHz lateral overtone bulk acoustic resonators transduced by aluminum nitride

Nai Kuei Kuo, Songbin Gong, Jeffrey Hartman, James Kelliher, Wayne Miller, Justin Parke, Silai V. Krishaswamy, John D. Adam, Gianluca Piazza

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

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.

Original languageEnglish (US)
Title of host publication2012 IEEE 25th International Conference on Micro Electro Mechanical Systems, MEMS 2012
Pages27-30
Number of pages4
DOIs
StatePublished - May 7 2012
Externally publishedYes
Event2012 IEEE 25th International Conference on Micro Electro Mechanical Systems, MEMS 2012 - Paris, France
Duration: Jan 29 2012Feb 2 2012

Publication series

NameProceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)
ISSN (Print)1084-6999

Other

Other2012 IEEE 25th International Conference on Micro Electro Mechanical Systems, MEMS 2012
Country/TerritoryFrance
CityParis
Period1/29/122/2/12

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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