Experimental study of temperature-compensated aluminum nitride Lamb wave resonators

Abstract

In this paper, the temperature compensation of aluminum nitride (AlN) Lamb wave resonators using edge-type reflectors is experimentally studied and demonstrated. By adding one compensating silicon dioxide (SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) layer with an appropriate thickness, the Lamb wave resonator can achieve a zero linear temperature coefficient of frequency (TCF). With the composite membranes including 1 mum AlN and 0.83 mum SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , a Lamb wave resonator operating at 711 MHz exhibits a secondorder TCF of -21.5 ppb/degC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The temperature-dependent frequency variation is less than 250 parts per million (ppm) over a wide temperature range from -55degC to 125degC. This temperature compensated AlN Lamb wave resonator is promising for future applications to thermally stable oscillators, filters, and sensors.