AVS 51st International Symposium
    MEMS and NEMS Monday Sessions
       Session MN-MoM

Paper MN-MoM8
Critical Issues in Epitaxial Growth of Pulse Laser Deposited AlN Films for MEMS and NEMS based RF Resonators

Monday, November 15, 2004, 10:40 am, Room 213C

Session: Processing and Characterization for MEMS and NEMS
Presenter: S. Hullavarad, University of Maryland
Authors: S. Hullavarad, University of Maryland
R. Vispute, University of Maryland
T. Venkatesan, University of Maryland
A. Wickenden, U.S. Army Research Laboratory
L. Currano, U.S. Army Research Laboratory
M. Dubey, U.S. Army Research Laboratory
T. Takacs, U.S. Army Research Laboratory
J. Pulskamp, U.S. Army Research Laboratory
Correspondent: Click to Email
AlN exhibits strong piezo-electric properties suitable for RF resonator applications. In this work we report the growth of highly oriented AlN films for MEMS and NEMS resonator devices. A multiple flexural structure of Pt/SiO2/Si is used as a substrate and films are grown by Pulse Laser Deposition (PLD) technique at a pulse energy of ~2J/cme2 with a repetition rate of 10 Hz. The process is optimized for the growth of AlN on different thicknesses of underlying SiO2. The films are characterized by XRD, RBS and techniques for crystalline quality and stoichiometry respectively. The interface analysis of underlying structures is analyzed in detail by RBS and oxygen content in the film is monitored by Resonant Oxygen Scattering technique. The morphology of AlN films is studied by scanning electron and atomic force microscopies. We have obtained highest Q factors for PLD grown AlN MEMS resonator beams of Q = 8,000 at fo = 2.5 MHz and Q = 17,400 at fo = 0.44 MHz We also address in this work critical issues related to (1) thickness of SiO2 (2) method of growth of SiO2 in fabricating MEMS and NEMS devices. These factors are very essential for the growth of high quality AlN films. However, SiO2 provides a amorphous underlayer for the growth of AlN leading to non in plane aligned AlN with respect to substrate. A lattice matching, epitaxial oxide layer like Y2O3 in place of SiO2 is going to be a unique solution for eventual epitaxial growth of AlN. We address the epitaxial issues of AlN and underlying oxide for improving the resonator properties of AlN based MEMS and NEMS devices.