Experimental investigation of thermal tuning for laterally excited bulk acoustic wave MEMS resonators using SOI bulk heating

Abstract

This paper presents the experimental investigation of electrothermal fine frequency tuning for a 60 MHz laterally excited contour mode bulk acoustic wave MEMS resonator, fabricated using the PiezoMUMPs multiprocess wafer process. Tuning is achieved via electrothermal SOI bulk heating of the resonator, so that its resonant frequency is shifted by inducing additional stresses in the device, as well as varying its elastic properties via a temperature change. Experimental results show that the resonant frequency decreases with an increase in the electrical heating power, which is applied to the resonator SOI bulk via two heating electrodes. For a 50-mW heating power swing, the resonator frequency varies from 61.368 MHz to 61.418 MHz. Measured results show that the SOI bulk resistance remains approximately constant over this tuning range, with a value of around 31 Ω . The discussion of the experimental results is aided and confirmed via finite element modelling and simulation.