Prediction of wafer handling-induced point defects in 300 mm silicon
wafer manufacturing from edge geometric data
Abstract
Abstract- For the miniaturization of the structures of semiconductor
device fabrication, high uniformity of side-flatness and edge roll-off
of 300 mm wafers are required. In this study, the formation of light
point defects (LPDs) on silicon (Si) wafer surface due to an edge
gripper handling system was investigated. The relationships between the
generation of LPDs with respect to flatness, edge profile, and edge
roll-off of Si wafers were analyzed. It was found that the variation of
traditionfacet parameters and near-edge geometry metric, such as edge
site frontsurface-referenced least squares/range (ESFQR), have no impact
on the formation of surface LPDs. By contrast, the performance of
Z-height double derivative (ZDD), allowed an accurate prediction of
formation of surface LPDs. Additionly, for a 300mm silicon wafer, the
surface LPDs occurred with frontside ZDD obtained at a radius of 149.2
mm, ranging above -954 nm/mm2 . The surface was LPDs free when ZDD was
below -1235 nm/mm2 . Surface LPD formation occurred randomly and was not
predictable when ZDD ranged from -954 nm/mm2 to -1235 nm/mm2 . The
result indicates that the LPDs caused by wafer handling is proportional
to the performance of ZDD at the edge roll-off area of silicon wafer,
this is consistent with the requirement of edge roll-off considering
wafer geometry.