Study On Deposition And Properties Of ZnO/Diamond Multiple Films For High-frequency Large-power SAWF

Due to a large amount of heat producing(up to several KW/cm2),smaller size,higher power SAW devices easily lead to its local overheating which decrease both the stability and the life of SAW devices.It is one of SAW devices' key issues which should be resolved.With obvious advantages of excellent thermal conductivity(20 W /(Kcm)),faster surface acoustic wave speed and very high resistance.Diamond is a better choice for acoustic wave filter(SAWF) with multilayers films than Si.It meets the SAW deceives' requirements of higher frequency and greater power.For diamond is not piezoelectric,we need deposited piezoelectric thin film(such as ZnO) on it to make up SAW devices.Except ZnO's natural excellent piezoelectric properties,high electrical and mechanical.coupling coefficient,low temperature coefficient and a small dielectric constant,other respects for example good c-axis orientation,small grains uniform,smooth surface can improve SAW devices' frequency and power.This paper focus on the preparation of large power SAW filter compose of ZnO/IDT/Diamond multi-films.Our study work as follow:First,the principles of the multi-film SAWF were expounded;Secondly,1.The thermal conductivity of the diamond / silicon multi-films was studied.The interface of multi-film is one of the most critical factors which affect the thermal conductivity.2.Using RF magnetron sputtering method,prepared ZnO films on Si and ZnO substrate respectively,studied the influnces of the substrates' temperature.The films were analyzed by XRD,SEM and other means.Get the result that when the power is 100W,argon oxygen ratio is 8:4 and the pressure is1Pa,the optimal temperature of Si substrate is 350℃.For diamond substrate,when the power is 80 W,argon oxygen ratio 7:5 and the pressure 1Pa,the optimal temperature is 220℃.We prepared high degree of c-axis orientation of the ZnO films on the substrate of unpolished Si,polished Si and polished diamond,the FWHM of the rocking curves of ZnO films were 7°,2.5°,3°respectly.3.Using DC magnetron sputtering method,prepared A1 film on the Si,then ZnO films on Al film by RF magnetron sputtering.The films were analyzed by XRD,SEM and other means. The influence factors of ZnO c-axis orientation in thin film were analyzed.We get a result that the roughness of the Al films is the main factor affecting the orientation of ZnO thin films, Prepared high-quality A1 films on diamond substrate by electron beam evaporation method then fabricated IDT using NLL.XRD showed that the ZnO films were highly c-axis preferred.In conclusion,through a series of tests,this paper study the thermal conductivity of diamond,furthermore,grope for the deposited process of ZnO thin film on both Si and diamond,lay a foundation for ZnO/IDT/Diamond multilayer structure of the SAW filters.