Paper MN-MoM4
Growth of AlN by Pulsed Laser Deposition and Reactive Sputtering Techniques and Fabrication of RF MEMS Resonators

Monday, October 15, 2007, 9:00 am, Room 615

AlN is a desirable piezoelectric material for MEMS and NEMS resonators and micro-switches for high frequency filtering applications. The theoretical maximum frequency of AlN is >180 GHz, as opposed to <60 MHz for PZT. The Young’s modulus of bulk ceramic AlN at 25°C is 345 GPa, and the density is 3260 kg m-3. This compares to a Young’s modulus of 56 GPa for thin film PZT, and a density of 7600 kg/m3 measured for bulk PZT. Additionally, AlN is better suited for the integration of MEMS devices into silicon-based electronics due to its complete compatibility with conventional silicon technologies.¹ In this work, the growth of AlN by Pulsed Laser Deposition method and comparison of properties of AlN thin films with reactive sputter deposition method will be presented. The fabrication and performance of MEMS resonators on AlN thin films deposited by both Pulsed laser deposition and sputtering techniques on substrates consisting of Pt/SiO2/Si structures will be discussed. Special emphasis will be given to the quality (thermal stability, stress) of SiO2 (thermal or PECVD) used as a support layer in fabrication of MEMS resonators. The results obtained by Rutherford Back Scattering Spectroscopy and X-Ray Diffraction techniques to understand the structural stability, composition, crystalline quality of SiO2, Pt and AlN films will be discussed. The quality factor of the resonators in air and vacuum will be compared. It will be shown that the crystalline quality of the films affects the actutation properties of the resonator beams.

¹ S.S.Hullavarad, B. Nagaraj, V.N.Kulkarni, S.Dhar, R.D.Vispute, T. Venkatesan, K.A. Jones, M. Derenge, T. Zheleva, M. Ervin, A. Lelis, C.J. Scozzie, D. Habersat, A.E. Wickenden, L. Currano, M. Dubey, J. Electronic Materials 35, 777 (2006) - A short review.