GaN micromechanical resonators with meshed metal bottom electrode

Azadeh Ansari, Che Yu Liu, Chien-Chung Lin, Hao-Chung Kuo, Pei Cheng Ku, Mina Rais-Zadeh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

This work describes a novel architecture to realize high-performance gallium nitride (GaN) bulk acoustic wave (BAW) resonators. The method is based on the growth of a thick GaN layer on a metal electrode grid. The fabrication process starts with the growth of a thin GaN buffer layer on a Si (111) substrate. The GaN buffer layer is patterned and trenches are made and refilled with sputtered tungsten (W)/silicon dioxide (SiO2) forming passivated metal electrode grids. GaN is then regrown, nucleating from the exposed GaN seed layer and coalescing to form a thick GaN device layer. A metal electrode can be deposited and patterned on top of the GaN layer. This method enables vertical piezoelectric actuation of the GaN layer using its largest piezoelectric coefficient (d33) for thickness-mode resonance. Having a bottom electrode also results in a higher coupling coefficient, useful for the implementation of acoustic filters. Growth of GaN on Si enables releasing the device from the frontside using isotropic xenon difluoride (XeF2) etch and therefore eliminating the need for backside lithography and etching.

Original languageEnglish
Pages (from-to)1204-1212
Number of pages9
JournalMaterials
Volume8
Issue number3
DOIs
StatePublished - 17 Mar 2015

Keywords

  • Epitaxial growth
  • Gallium nitride (GaN) microelectromechanical (MEMS) resonators
  • Metal-organic chemical vapor deposition (MOCVD)
  • Piezoelectric

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