The Study Of Sapphire Wafer Of Ultraprecision Method

α-Al2O3, a single crystal material, developed and industrialized with the development of communication and information industries recently, owns the excellent performances such as excellent rigidity, excellent chemical stability, higher heat exchange, excellent insulation and good mechanical capability ,etc. However, researches onα-Al2O3 single crystal wafer around world are still lacking.α-Al2O3 wafers are machined usually by chemical mechanical polishing in industry. Based on the investigation of the mechanical property ofα-Al2O3 crystal wafer and theory analysis of polishing movement tracks, this thesis discuss its mechanical of CMP, present its polishing characteristic and analyzes the effects of polishing condition parameters upon CMP.For selecting suitable CMP condition, the movement of polishing was modeling and simulation. For bosseyed polishing, the analysised results show that the reasonable rotating speed and distance between workpiece plate center and polishing plate center are 60rpm and 100mm. For polishing machine, which is drive by four-bar mechanism, the analytical results show that the scales between the pad and the wafer of rotating speed are variable. When the scale is more than two, the result is the best. For double-sided polishing, the scales between the wafer and the inner gear of rotating speed are also variable, When the value is between 0.79 to 1.4, the effect is the best. Stimulation the distribution of the shear stress on the surface of theα-Al2O3, we may get the optimum parameters about the process of CMP. Generally speaking, the maximum of shear stress is always occurs at the edge of the wafers. When the rotating of the pad and the wafer is equality, the effect of the polishing is the best.The CMP experiment was carried out systematically onα-Al2O3. The polishing surface roughness and material removal rate in different polishing conditions were measured and the effects of polishing pad material and its condition, pressure, rotating speed of the polishing plate, the type and size of abrasive, and the properties of the polishing slurry on the surface roughness and material removal rate were analysed in details. We get the best parameter in the process of CMP, such as the press of pad is 400Pa and the time is 15minutes when we grind. While we polish the wafers, the rotating of the pad should be 70rpm and the rotating of wafer should be 30rpm, the press of the pad should be 100Pa.