Inclination Effects on Voltage-controlled Tuning of MEMS Disk Resonator Array Composite Fabricated by Deep Reactive Ion Etching Process
Haixia Yan, Jinyan Bao, Quan Yu, and Linxi Dong
(Received May 2, 2018; Accepted September 4, 2018)
Keywords: DRIE process, MEMS disk resonator array, electrostatic tuning, electromechanical coupling, motional resistance
Capacitive micro-electro-mechanical system (MEMS) disk resonators fabricated by a deep reactive ion etching (DRIE) process have large sensitive capacitances and small motional resistance. However, for the MEMS disk structure with a high aspect ratio, the cross section takes on a trapezoidal profile, which will affect the performance of the resonator. In this paper, we firstly analyzed the electrostatic tuning mechanism of electrical stiffness produced by the electrostatic force, and the dependence of resonance frequency variation on the inclination angle and dc bias voltage are obtained and the electromechanical coupling strength was changed owing to the inclination angle. Secondly, after analyzing the feasibility of overcoming the inclination effect by introducing a tuning disk array, the optimal tuning voltage of the inclined disk resonator array and the scale of the array with a small motional resistance can be obtained. The results show that for an array with the same inclination angle of 0.1° and biased at 10 V, when the tuning voltage is 20 V, the relative error of the resonance frequency can be reduced to 12.4 ppm. In addition, the optimal tuning voltage increases as the inclination angle increases, and when the inclination angle is 0.3°, the optimal tuning voltages are 28.68V and 57.35V for the dc bias voltages of 10 and 30 V, respectively. If the motional resistance need be reduced to 50 Ω, the integrated number of the disk resonator will increase to 1048, and the optimal tuning voltage can reach 37.5 V. These results can provide some theoretical basis for the large-scale integration of the disk resonator array in the future.
Corresponding author: Linxi Dong