Study On Deposition And Characteristic Of High Performance Piezoelectric Films For High Frequency SAW Devices

As the processing information amount of modern electronics increases rapidly, the carrier wave in communication must move to higher frequency band .Surface acoustic wave (SAW) filter is one of the key elements in modern wireless mobile-communication System The central operating frequency of SAW filter (f) is defined as f=V/L, among which V means the SAW speed of the used material, and L is the period of its interdigital transducer(IDT). At present, it is difficult for SAW devices operating under GHz frequency because of the limitation of materials and fabrication technology. Diamond have a very high acoustic speed, and it is possible to fabricate GHz SAW devices using piezoelectric films on diamond substrates based on the present technology Nowadays, it is competition to fabricate GHz SAW devices using diamond substrates.In this thesis, we deposited zinc oxide (Zn0) films on silicon and diamond substrates by radio frequency(R.F)magnetron sputtering. We have also explored the fabrication technology of ZnO films. The zinc oxide thin films are structurally analyzed using techniques such as bragg X-ray diffraction,scanning electron microscopy,atomic force microscopy to determine their crystal structure,surface morphology and composition distribution. The main results can be described as following:First, we have investigated the deposition of ZnO films on Si substrates ,the effects of sputtering temperature,sputtering pressure,sputtering power,proportion of oxygen and argon and annealing temperature on microstructure and electricity performance of ZnO thin films are also discussed. Results optimized those the deposition parameters,under the condition highly c-axis oriented ZnO thin films with lower surface roughness(RMS:2.038nm)and high resistivity above 107?.cm have been fabricated.Second, we deposited ZnO films on diamond substrate and discussed effects of deposition parameters. Experimental results show under the optimized condition highly c-axis oriented ZnO thin films with lower surface roughness(RMS:1.2nm)and high resistivity above 107?.cm have been fabricated.Finally, we explored the fabrication technology of LiNbO3 thin films, Our resultsshow that it is possible that the piezoelectric films can be fabricated by RF magnetron sputtering.In a word, with a series of research ,the paper discussed the effect of the deposition parameters on microstructure and electricity performance of ZnO thin films, under the optimized condition highly property ZnO films are fabricated which are suitable for the fabrication of surface acoustic wave device.