Preparation Of Diamond Multiplayer For Surface Acoustic Wave Filters

Amongst the varieties of applications of CVD diamond, the Surface Acoustic Wave (SAW) device is supposed to be one of the practical applications for its high SAW velocity. In the communications area, the demand of high frequency and high bit rates is increasing to meet the requirements for broadband, mobile and optical communications systems. In particularly, devices with frequency on the GHz range and/or a high power capability, which are hard to be realized via SAW deices using conventional materials such as quartz, lithium niobate (LiNbO₃) and lithium tantalite(LiTaO₃), are strongly required. Due to the progress made in CVD-diamond growth technology, SAW devices fabricated by structures with diamond have been studied and were found that systems involving these materials were practical for high-frequency SAW filters.In this paper, ZnO/diamond multilayer structure for high-frequency SAW filer was fabricated under the support of key item of Tianjin Nature Science Foundation (800611). Firstly, dense smooth diamond films were prepared by hot-filament CVD. The influence of carburized or un-carburized filaments on the growing process was discussed. The method of improving the density of nucleation by a diamond-like pre-coated layer in diamond preparation was obtained. Secondly, piezo-electric films ZnO were deposited by magnetic sputtering. Zinc oxide films were deposited on Si by DC plane magnetic-control sputtering. And the influence of parameters on the structure of ZnO films was also investigated. ZnO/diamond multilayer structure was prepared by RF magnetic-control sputtering. Furthermore, the SAW characters of multilayer structure films were studied through XRD LAMAN and so on.