Investigation of the Effect of Grain Size Variation on Ground Wafer Surface by Grinding Experiment/Simulation

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The grinding wheel is comprised by three elements; abrasive grain, bonding material and pore, which are specified by five factors; type of abrasive grain, grain size, type of bonding material, grade of hardness and abrasive grain volume percentage. Regarding the abrasive grain, it is well known that shape and number of cutting edge significantly effects grinding performance such as surface roughness, grinding force and grinding wheel life. In general, abrasive grain size is determined by mean diameter of abrasive grain. However, the abrasive grains in a grinding wheel are randomly scraggly in size and shape. There is no particular aspect to regulate the grain size variation in JIS (Japanese Industrial Standards). This paper investigates the effect of grain size variation on the ground surface topography by actual grinding on silicon wafers and analysis based on grinding simulation. The results reveal that the standard deviation of grain size is a very important index to characterize the grinding performance of a wheel. Smaller standard deviation leads to larger density of effective cutting-edge under the same volume percentage of abrasive grain contained in the wheel. This fact significantly contributes to not only achieve a better surface roughness and more uniform surface integrity, but also shorten the finishing time.