Lamé Resonator Integrated With Chevron-Shaped Thermal Actuators to Improve Motional Resistance and Temperature Stability

Abstract

This paper presents a capacitive bulk mode resonator operating in Lamé mode, where the motional resistance and temperature stability are enhanced by implementing a set of chevron-shaped thermal actuators to reduce the transducer air gaps. The chevrons are heated using micro-heaters that are integrated on the actuator. The device is fabricated in the PiezoMUMPS standard microfabrication process by MEMSCAP. The measured resonant frequency for the fabricated device was observed to be 17.9 MHz. It has been experimentally shown that the transducer air gap can be reduced from 2.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu m$</tex-math> </inline-formula> to 0.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu m$</tex-math> </inline-formula> by applying a heater voltage of 2.7 V at atmospheric pressure. In the proposed resonator, the transmission loss can be reduced by 8.54 dB when the actuators are biased at 1.8 V in vacuum, as opposed to when the actuator is off. Under these conditions, the thermal actuators each consume 39 mA. In addition, the implemented thermal actuators can function as integrated heaters that increase the temperature of the suspended square structure to compensate for ambient temperature variations. As such, applying a voltage of 1.8 V in vacuum reduces the resonant frequency from 17.95 MHz to 17.91 MHz, while applying a voltage of 2.6 V at atmospheric pressure reduces the resonant frequency from 17.97 MHz to 17.86 MHz.2022-0188