Study On Acoustic-Driven Magnetoelectric Antenna Based On Thin Film Bulk Acoustic Resonator

With the rapid development of electronic products and the advent of 5G communication era,higher requirements have been put forward for the miniaturization,efficiency and integration of antennas.The traditional antenna is driven by current or voltage,and the antenna size is comparable to the electromagnetic wavelength,between0.1λ₀ and 0.5λ₀（λ₀ is the electromagnetic wavelength at operating frequency）,which is difficult to miniaturize.Acoustic driven magnetoelectric（FBAR ME）antenna based on thin film bulk acoustic resonator（FBAR）is one kind of mechanical antennas,which works at acoustic resonant frequency.Since the wavelength of acoustic wave at the same frequency is four to five orders of magnitude smaller than that of electromagnetic wave,the antenna size is one to two orders of magnitude smaller than that of compact antenna,which provides a great opportunity for miniaturization of wireless communication system,and has very promising applications.At present,the research of acoustically driven magnetoelectric antenna just begins,and most works of domestic and foreign groups mainly focuse on the design,numerical simulation and theoretical calculation of the antenna,but there are fewer reports on the fabrication and test.In this thesis,in order to improve the bandwidth and gain of magnetoelectric antenna,and I have carried out theoretical analysis and finite element simulation,and explored the preparation process of important functional layers of the device.FBAR magnetoelectric antennas with single-cavity and multi-cavity structure have been fabricated and tested.The main research contents and conclusions of the thesis are as follows:Firstly,the working principle of the FBAR magnetoelectric antenna is discussed,and the finite element simulation analysis of FBAR magnetoelectric antenna using COMSOL software is carried out to investigate the effects of the thickness of magnetic layer and resonant cavity shape on the performance of the device.The simulaton results show that the thicker the magnetic layer,the better the performance of the device.Among the devices with rectangular,elliptical and pentagonal resonant cavity structures,the later two antennas have better performance.Secondly,the preparation process of the important functional layers of the device was studied.The（110）-oriented Mo electrode films were prepared by DC magnetron sputtering,and the effects of sputtering power,Ar pressure and other factors on the orientation of Mo films were investigated.Then,the effects of nitrogen-argon ratio and film thickness on the（002）orientation of Al N and Sc Al N films were investigated,and the preparation process of c-axis oriented piezoelectric films by RF magnetron reactive sputtering was optimized.Finally,the FBAR magnetoelectric antenna devices based on Al N/Fe Co Si B magnetoelectric heterostructures were prepared and tested.The single-cavity and multi-cavity FBAR magnetoelectric antenna devices were prepared by the MEMS process.The resonant cavity shapes of the single-cavity FBAR magnetoelectric antenna are rectangular,elliptical and pentagonal,respectively.On-chip tests of the antenna were carried out on a lab-built magnetoelectric antenna test system,and the results show that the rectangular resonant cavity antenna has the best performance with the operating frequency of 838MHz and the transmission characteristic S₂₁ parameter peak between the transmission antenna and the magnetoelectric antenna measured is-25.231d B.In addition,multi-cavity FBAR magnetoelectric antennas with 250,500 and 750 nm thickness of Fe Co Si B magnetostrictive layer have been prepared.On-chip test results shows that the antenna with 500 nm thickness has the best performance with the operating frequency of 895 MHz and the transmission characteristic S₂₁ parameter peak between the transmission antenna and the magnetoelectric antenna measured is-28.337d B.The series-parallel multi-cavity structure can effectively widen the bandwidth of the magnetoelectric antenna,and the3d B bandwidths of 250,500 and 750nm magnetoelectric antennas are 15.6,11.8 and 10.9MHz,respectively.These devices have also been packaged and tested in a microwave darkroom,and the results are discussed...