Temperature Compensation of Aluminum Nitride Lamb Wave Resonators Utilizing the Lowest-Order Symmetric Mode
Technical Report Identifier: EECS-2012-264
Abstract: In this work, temperature compensation of AlN Lamb wave resonators (LWRs) using the lowest-order symmetric (S0) Lamb wave mode is theoretically and experimentally investigated. By adding a compensating layer of silicon dioxide (SiO2) with an appropriate thickness ratio to the aluminum nitride (AlN) thin film, the AlN/SiO2 LWR can achieve a low first-order TCF at room temperature. In addition, LWRs with an AlN layer as thin as 250 nm are proposed to realize the temperature compensation over a wide frequency range from 100 MHz to 1 GHz. Using a multilayer plate composed of 1-?m-thick AlN and 0.83-?m-thick SiO2, a temperature-compensated AlN/SiO2 LWR operating at a series resonance frequency of 711 MHz exhibits a zero first-order TCF and a small second-order TCF of -21.5 ppb/C^2 at its turnover temperature, 18.05 degree C. The temperature dependence of fractional frequency variation is less than 250 parts per million (ppm) over a wide temperature range from ?55 to 125 degree C. The temperature-compensated AlN LWR is promising for future applications including thermally stable oscillators, filters, and sensors.