大口径シリコンウエハ研削加工における幾何と運動

Abstract

To address the problems of throughput rate, post-process cleaning, environmental aspects as well as to achieve the total surface integrity for large-scale silicon wafers, the semiconductor industry is looking for a fixed abrasive solution as the alternative. As the result of intensive RD 1) the cutting path pattern is determined only by the rotational speed ratio of the wafer against the wheel. 2) Once the grinding reaches the steady state, the cutting edge goes over the same path so that the cutting path pattern remains unchanged. Three problems have then been addressed from the cutting path pattern; 1) Different rotational speed ratio grants a different cutting path density, thus achieves significantly different surface roughness. 2) The cutting path density in the wafer center is higher than that at the fringe so that the surface toughness is inconsistent over the whole wafer. 3) The vaziation in the cutting path density also leads the ground wafer to a concave profile. Solutions are proposed on the basis of analytical and experimental results. 1) The criteria to terminate the grinding proccss are established to improve the surface roughness. 2) The whecl geometry is optimized to attain a consistent cutting path density. The results achieved in this research are also applicable to the generation of large-scale flat surface other than silicon wafer.