Experiment Research And Theoretical Analysis Of Multi-wire Slurry Sawing Silicon Wafer’s Surface Roughness

With the rapid development of photovoltaic industry and electronic industry, solar silicon wafer production demand is growing. In view of the silicon wafer, the development trend of large diameter, thin semiconductor cutting technology has been gradually by inside circle cutting into line. Free abrasive wire cutting technology with high efficiency, small incision material loss, wafer cutting surface damage layer of shallow, and many other advantages, especially for large diameter silicon rod cutting, and can simultaneously multiple slice of silicon rod. The size of the surface roughness is one of the important indicators of evaluation of quality of silicon wafer processing, in order to get a lower surface roughness, the need for a large number of complex experiments to explore the influences of cutting parameters on surface roughness. For the free abrasive wire cutting silicon crystal surface quality and machining precision, and develop a broader research scholars both at home and abroad. Due to the free abrasive wire saw in the process, many factors affect surface roughness of silicon wafer, and special ways of the movement, and the mechanical properties of single crystal silicon material is different from the metal material, in order to improve the wafer surface quality and machining precision, and to establish the free abrasive wire saw silicon crystal surface roughness Ra of the forecasting model is of great significance.Based on the brittle material under quasi-static indentation fracture mechanics model, considering the free abrasive wire cutting process of abrasive under a state of full contact way of "rolling-embedded" movement, theoretical analysis of the free abrasive wire saw mechanical behavior and material removal in the process of form, the model of surface roughness Ra; And the simulation analysis of the wire speed, feeding speed, tension, concentration of abrasive particle size, cutting fluid, the influence of the length of cutting area of the law. At the same time, through the single factor experiments, analysis the influence of process parameters on surface roughness, and synthesize curve to fit the experimental data, it is concluded that surface roughness Ra of the experience formula of the various factors, respectively. The fitting curve and comparative analysis, the simulation curve is given to prove the validity of the theoretical model. Through the orthogonal experiment on the wafer surface roughness and the total thickness of the free abrasive wire cutting deviation, process optimization, and discusses the main factors of the interaction between, finally it is concluded that surface roughness Ra using the method of multiple regression empirical formula, the consistency of the test and theory formula.In this paper, the main research results are as follows:1) The theoretical analysis of the free abrasive wire cutting process of abrasive rolling force and material removal rate, through to the abrasive movement form and contact state, single particle removal volume, grinding, cutting lines, and the distribution of grinding force between particles is analyzed, the effect of single diamond grits is obtained in the normal force and tangential force.2) To establish the relationship between surface roughness Ra with various process parameters. Silicon wafer surface roughness Ra with the tensioning force of wire walking speed, cutting line, cutting fluid decreases with the increasing of the concentration, as the workpiece feed speed, abrasive particle size and increased with the increasing of silicon rod diameter.3) The value prediction model is proved to be correct by experiments. Compare the fitting formula of various process parameters on surface roughness Ra index items influence weight from big to small in turn is:feed speed, initial tension, silking, the length of the cutting area, cutting liquid concentration, abrasive particle size.4) Through the orthogonal experiment on the wafer surface roughness and the total thickness of the free abrasive wire cutting deviation for process optimization of the interaction of the factors are analyzed, and the surface roughness Ra was obtained by multiple regression method the empirical formula.