Piezoelectric-on-silicon lateral bulk acoustic wave micromechanical resonators

This paper reports on the design, fabrication, and characterization of piezoelectrically-transduced micromechanical single-crystal-silicon resonators operating in their lateral bulk acoustic modes to address the need for high-Q microelectronicintegrable frequency-selective components. A simple electromechanical model for optimizing performance is presented. For verification, resonators were fabricated on 5-mu m-thick silicon-on-insulator substrates and use a 0.3-mu m zinc oxide film for transduction. A bulk acoustic mode was observed from a 240 mu m x 40 mu m resonator with a 600-Omega impedance (Q = 3400 at P = 1 atm) at 90 MHz. A linear resonator absorbed power of -0.5 dBm and an output current of 1.3 mA rms were measured. The same device also exhibited a Q of 12 000 in its fundamental extensional mode at a pressure of 5 torr.