Study On Deposition And Engeneering Of ZnO/Diamond Multiple Films For High Frequency SAW Devices

Surface Acoustic Wave (SAW) Device has the characteristic of mini capacity, high reliability, multiple-function and good coherence, so it have being used widely in the scope of radar, electronic battle, sonar, wireless communication, optic communication and broadcast system.Center frequency of SAWF was decided by SAW velocity V and the IDT's cycle-width L, that is f=V/L. Now, with transport of mass data and increasing of mobile communication, communication frequency band extend to high frequency and high-frequency SAW filter was urgently needed. Because of the limitation of material and process technology, it is hard to reach GHz frequency for general SAWF. Diamond has much high velocity of SAW, so the SAWF adopted diamond as underlay can easily reach GHz frequency and it turns to be a hotspot in international.Because of different emphasize point in our task-team, this thesis mostly studied on diamond deposition which fit SAW filter. ZnO/IDT/Diamond multi-film SAW filter require diamond film has smooth surface, low vice density and so on, in order to be advantageous to deposit aluminium film to fabricate IDT. Because the IDT was very thin, it required the diamond film surface has high smooth rate in order to minish insert-waste and low vice density to minish transmit-waste.Surround manufacture of SAW device, this thesis do these works as follows:First, expatiate the theory of multi-film SAW device;Second,1, Adopting MPCVD skill, we deposited diamond film on <100> mirror-polished Si flake. Using XRD, SEM, Raman testing method, we proved this film to be <004> high tropism and high quality diamond film.2, Studyed diamond's growth on different type Si flake, XRD spectrum indicate that on <111>Si flack, the diamond film growed has relatively more <111> tropism.3, Studyed influence of temperature to diamond tropism. With temperature fall, the shape of diamond transform from hexahedron to octahedron.4, In the process of growth, diamond crystal can not grow more and more big infinitely like column, with restrain of different tropism crystal, it reach a steady size. In this thesis, we also explored diamond growth mechanism elementarily.Besides, introduced designing method of SAW filter briefly.To sum up, through a series of study, this thesis studied influence to diamond growth adopting different deposition teachnology and do some elementary exploration to CVD mechanism, established foundation to next step to facture SAWF of ZnO/IDT/Diamond structure.