The Piezoelectric Single Crystal Surface Quality Of Micro-analytical Studies

Piezoelectric crystals, which has high reliability good repeatability and low surface acoustic wave (SAW) transmission loss performances, have been broadly used in many fields of SAW devices, such as filter, transducer, sensor and so on. Due to the advances in microwave communication systems such as personal telephone, satellite communication and optical communication, the demand for high frequency SAW filters is remarkably increasing, that has brought forward harsher request to the surface quality of the single crystal wafer meanwhile. But at present there are apparent differences in abroad. The surface quality of the crystal wafer, which great affecting the yield and high frequency properties of the SAW devices, have certain economic prospect and application background owing to this aspect research, yet at present still be short of systematic research and sufficient taking seriously. The surface quality of the niobic acid lithium and quartz, the two applying broad crystals, are studied in this project, Apply microcosmic analysis, the relation between microstructure, processing technics and its performance are studied as well.The characterization techniques and methods involved in the assessment of single crystal wafer damages have been discussed briefly in this paper, its features and applications are presented also. For the different interaction principle, results of surface damages analyses obtained by those methods maybe discrepancy in some degree.For evaluation of the processing technics for single domain, Ferroelectric domain structures of the LiNbO3 crystal wafer was studied in this paper by scanning force microscopy. Surface quality of the LiNbO3 crystal wafer was studied, including surface topography, potential distribution and machined damage layer. Through analyzing sample which exist discrepancy high frequency performances by different processing technics, the aspects which great affecting the high frequency properties of the SAW devices, have been found out such as small angle crystal boundary, surface damage, potential and electricity parameter distribution. Comply with the processing technics the causes is discussed, according to the analysis outcomes suggestions on how to optimizes are given. The surface damage layer in the quartz crystal wafer of 36°AT-Cut induced by Chemical-mechanical polishing was analyzed quantitative by scanning electron microscopy and X-ray rocking curve measurements after the wafer was chemically etched, moreover discussed the reason of formed damage layer and the influence of device performances. Through a method of coordinate transformation for studying the quartz crystal wafer of 36°AT–Cut, The values of the piezoelectric coefficients matrixes elements for the cuts of the crystals of Quartz are obtained and their curves are given by the program of Matlab.This project mainly provide a way for material and device worker of acquaintance the control of the effect of crystal surface quality to quality of device, make them optimize produce flow, improve the progress of crystal and device quality.