Sputtered C-Axis Inclined ZnO Films for Shear Wave Resonators

Abstract

This paper reports on the growth and characterization of ZnO films having C-axis oriented 40° to the substrate normal. These films are of significant i nterest for shear wave generation for bulk wave delay lines and resonators. The films were grown on Si wafers or membranes under low pressure and high growth rate conditions in a reactive dc planar magnetron sputtering system having an auxiliary anode structure. resonators were fabricated and used for film evaluation. A ZnO/Si composite resonator exhibited a Q of approximately 4600 at 293 MHz fundamental resonance. The effective coup ing c oefficient of the film alone was found to be 17% (k2=.029) using an edge-only supported ZnO pla e resonator. The temperature coefficient of the ZnO resonator was found to be -36 ppm/CO and -20.5 ppm/CO for the composite structure. Shear wave