Study Of PZT Piezoelectric Film Acoustic Resonator

With the rapid development of wireless communication technology,day's strong market demand of the communication terminal functional,and the strict requirements of spaceborne,airborne,missile and other electronic systems for component factors,such as volume,power consumption,developing high frequency devices with a high Q value,miniaturization,integration characteristics become a key part of wireless communication.This paper proposed an acoustic resonator based on PZT piezoelectric effect film,which is of great significance to the development of high performance frequency devices.This paper discussed the working mechanism of the acoustic resonator of thin film body and described the equivalent model and modeling method of FBAR device in detail.Using ADS electrical simulation and Comsol finite element simulation,The influence of physical structure,including the thickness and types of piezoelectric material,kinds and shape electrode materials and resonant area,on FBAR impedance characteristics is studied.Based on the simulation results,the device size is optimized and the displacement distribution of the piezoelectric layer in the resonant center is analyzed under the optimal size.Based on the strain range of PZT piezoelectric film,the feasibility of the device structure was demonstrated.Combining with MEMS processing technology,the machining technology of the device was determined and the layout design was completed.Using sol-gel technology,the PZT piezoelectric thin film was integrated on wafer lever,the piezoelectric thin film with good film density,good orientation and uniform thickness was obtained,and the material properties of FBAR devices are best matched.The preparation of thin film bulk acoustic wave resonator basic chip was completed by using MEMS silicon and planar processing technology,and aiming at the technical bottleneck of low support layer releases yield,the TMAH gas phase with a high uniformity and low roughness array of bulk silicon processing etching method was proposed,which solved the problem of wet etching technique for high quality film release.Finally,we built the test platform to complete the prototype S parameter test.The experimental results show that the base chip series resonance frequency of 1.147 GHz,parallel resonant frequency of 1.209 GHz,bandwidth of 62 M HZ,and device electromechanical coupling coefficient is 12.65%,which have small difference with the simulation results,and a satisfactory experimental result are obtained.