Fabrication and characterization of zinc oxide piezoelectric MEMS resonator

Micro electromechanical system resonators (MEMS) are being explored to fulfil the demands of speedy wireless communication circuits, which may be utilized as oscillators and/or filters in radio transceivers. Micro resonators of radio frequency range are involved in variety of commercial applications as a replacement of traditional bulky devices due to their small size, high quality factor and most importantly CMOS compatibility. In this work, the design and fabrication of laterally vibrating contour mode MEMS resonator of global system for mobile communication range frequency is presented. Zinc oxide (ZnO), a green piezoelectric material has been used. The ZnO films can also be deposited at low temperature thus reduces thermal budget. An excellent biocompatible/biodegradable property of ZnO may also be useful in resonators used as the detector for mass/pressure sensing for medical applications. The performance of fabricated MEMS resonator is validated by numerical simulations and experimental electrical characterization. The results show that the resonator may be deployed for radio frequency communication. The process to fabricate the resonator has been developed and the devices have been fabricated by surface micromachining techniques on silicon wafer using two electron beam, two optical lithography processes and simple and cost-effective wet etching method used for ZnO etching over costly DRIE process. Graphic abstract