Research Of Piezoelectric MEMS Resonators In High Frequency

The MEMS resonators with piezoelectric transduction mechanism have attracted much attention in recent years.Piezoelectric-excited MEMS resonators can overcome limitations such as the limitation between dynamic resistance and non-linearity as well as the need for bias voltages in MEMS resonators for capacitive resonators and piezoresistive switching.Therefore,piezoelectric resonators have smaller dynamic impedance and insertion loss than other types of resonators.However,the disadvantage of piezoelectric resonators is that they have low quality factor Q,especially in pure piezoelectric MEMS resonators.This is due to the piezoelectric resonator having material and electrode loss and energy loss such as anchor loss.Among the losses,the anchor loss is the main source of losses,which is also the most important factor that limits the Q value of MEMS resonators.The goal of this paper is to design and fabricate high-Q piezoelectric resonators,including two types: the phononic crystal resonator and the ring-shape resonator.This paper firstly introduces the principle of MEMS resonator,and then introduces the design process and result analysis of phononic crystal resonator and ring-shape resonator in detail.In this paper,we designed a MEMS resonator with two-dimensional phononic crystal structure on the support beam.The anchor loss of the resonator is an important factor in determining the Q value of the resonator,especially at high frequencies.During the resonance,a portion of the energy stored in the resonator is transferred to the substrate by support anchors in the form of elastic waves.Based on the TPoS resonator,the phononic crystal resonator adds a phononic crystal structure,which can reduce the energy loss and improve the Q value.In this paper,the bandgaps of phononic crystals are simulated,the bandgap frequency range is from 100 MHz to 110 MHz,and the design of the two kinds of phononic crystal resonator resonant frequency is also within this range.In this paper,we also studied the influence of the size of the designed phononic crystals on the center frequency and width of the bandgap by simulation,and summarized the most important factors to facilitate the follow-up study.In the final design and processing of several resonators,80?m long resonator with 5 phononic crystals by the experimental test at 109.85 MHz reached the highest Q,9744.In this paper,we also designed a resonator with a ring shape resonate body,the resonators including a single electrode ring and a resonator with interdigital electrodes.Both of these resonators were modeled in COMSOL and several resonate modes were obtained.Among them,the interdigital-electrode resonators have a more even charge distribution and more uniform resonance force,so the Q value is higher and IL lower than that of a single-electrode circular resonator.After testing,the interdigital-electrode ring resonator reaches the highest Q value of 9959.6 at 83.58 MHz.In summary,the two high-Q piezoelectric resonators designed in this paper all exceed the highest Q value of over 9,000,reaching the expected goal.