Abstract:

During the integrated circuit manufacturing process, ultra-precision grinding based on the principle of wafer rotation grinding is currently utilized as a major method in flattening and back-thinning of large-size silicon wafers. Grain depth of cut is a function to characterize the overall grinding conditions and has direct effect on the surface/subsurface quality of ground workpieces. Modelling of grain depth of cut of workpiece rotation grinding has great significance in grinding of silicon wafers with high efficiency and high surface layer quality. Based on the analysis of relative motion between cup-type grinding wheel, abrasives and silicon water in wafer rotation grinding, the model of grain depth of cut is proposed and the mathematical relationship among grain depth of cut, dimensions of cup-type grinding wheel, grinding parameters and radical distance is presented. With the proposed model, the subsurface damage distributions along the radical direction of ground silicon wafers and the effects of machining conditions on subsurface damage in wafer rotation grinding are then analyzed, and the grinding experiments are conducted to verify the model. The experiment results show that the subsurface damage depth decreases gradually along radical direction from edge to centre of the ground wafer surface. The subsurface damage depth increases with the increase in wheel grain size, wafer rotation speed, wheel feedrate and the decrease in wheel rotation speed. The experiment results agree well with the model predictions.

Key words: grain depth of cut, grinding, subsurface damage, silicon wafers