Finite Element Simulation Of Diamond Multilayered Structure Surface Acoustic Wave Devices

5G communication systems will have a higher transmission rate,which will bring great convenience to people's lives.Radio Frequency?RF?surface acoustic wave?SAW?filters and duplexers are the core devices of 5G wireless communication.5G is expected to adopt bands above 3GHz.Therefore,high frequency is an important direction for the development of SAW devices which means that the interdigital transducer lines develop in the direction of micro-refinement or SAW velocity of materials develops in higher direction.Micro-refinement of lines lead to the withstand power of devices dropping sharply.So increasing SAW velocity of materials is the main way.Diamond has the highest velocity among all the known materials.It is required to deposit a layer of piezoelectric film on diamond because of its non-piezoelectricity.However,with the increasing of layers the complexity of simulation and calculation about SAW propagation characteristics improves greatly from single layer to multilayer.Traditional analytical methods will be more complex and less accurate.But finite element method?FEM?can improve the accuracy of simulation and calculation.In this article,firstly the structure and working principle of diamond multilayered structure SAW devices are introduced.Then COM equations about SAW devices and the calculation of SAW propagation characteristics parameters with FEM were emphasized.As for SAW devices of piezoelectric film/diamond structure,the influence of different orientations of ZnO on SAW excitation modes and propagation characteristics were systematically investigated in ZnO/diamond structure.Through the result of simulation,a higher SAW velocity and electromechanical coupling coefficient K² about Rayleigh mode can be obtained in?100?ZnO/diamond structure.The maximum electromechanical coupling coefficient K² of love mode reached 4.26%in this structure.The temperature coefficient of frequency?TCF?of love wave was improved by adding a layer of SiO₂ and its value was closed to zero.??100?AlN/?100?ZnO?_N/diamond periodic multilayered structure was designed,which further improves SAW phase velocity of ZnO/diamond structure under the premise of obtaining a sufficiently large electromechanical coupling coefficient K².The propagation characteristics of Sezawa wave and influences of different electrode position on this structure were investigated at N=1 and N=2?It hasn't been reported so far?.Through the result of simulation,theperformanceofSAWpropagationismoreexcellentin??100?AlN/?100?ZnO?₂/diamond structure.Finally,SAW oneport resonators and delay line of??100?AlN/?100?ZnO?₂/diamond structure were designed and simulated based on the optimized diamond multilayerd structure parameters.And the influence of electrode reflection was considered.Through the result of simulation,it is found that increase of electrode thickness will increase reflection coefficient,which has a great influence on the parameters of S₁₁ and S₂₁.Therefore,when SAW oneport resonator constitutes a ladder structure filter,a thicker electrode at h_IDT/??9%can be selected,and a delayed line type SAW filter needs to select a thinner electrode at h_IDT/??1%.