Diamond-based capacitive micromachined ultrasonic transducers


Bayram B.

DIAMOND AND RELATED MATERIALS, vol.22, pp.6-11, 2012 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 22
  • Publication Date: 2012
  • Doi Number: 10.1016/j.diamond.2011.11.006
  • Title of Journal : DIAMOND AND RELATED MATERIALS
  • Page Numbers: pp.6-11
  • Keywords: Capacitive micromachined ultrasonic transducer, Ultrananocrystalline diamond, Plasma-activated direct bonding, Microelectromechanical devices

Abstract

Capacitive micromachined ultrasonic transducers (CMUTs) employing diamond membranes are demonstrated. The design, finite element modeling, microfabrication, and experimental characterization of diamondbased CMUTs are reported. Ultrananocrystalline diamond having a chemical mechanical polished silicon dioxide interlayer deposited via high temperature oxide (HTO) process at 850 degrees C in a low pressure chemical vapor deposition (LPCVD) furnace is employed as the membrane to form vacuum sealed cavities using plasma-activated direct bonding technology. Electrical impedance, deflection, and transmission measurements of a fabricated CMUT are performed in air using an impedance analyzer, a white light interferometer and a hydrophone, respectively. Experimental results verify the accuracy of finite element modeling. Diamond-based CMUTs possess 3-dB fractional bandwidth of 3% at a center frequency of 1.74 MHz in air. Our experimental results demonstrate diamond as an alternate membrane material for CMUTs, and that diamond can be employed in novel microelectromechanical devices. (C) 2011 Elsevier B.V. All rights reserved.