公开(公告)号：EP1180251A1

公开(公告)日：2002-02-20

申请号：EP01918374.8

申请日：2001-03-05

申请人： Koninklijke Philips Electronics N.V.

发明人： HUBBARD, Bryan ,  LEROUX, Pierre

IPC分类号： G03F9/00

CPC分类号： G03F9/7092 ,  G03F9/7076

摘要： A method for determining the centroid of a wafer target. In one embodiment, the method comprises a series of steps in a stepper, starting with the step of receiving a wafer, having a target set formed therein. Next, a signal is passed over the target set and over a material separating target shapes in the target set. Then a return signal is reflected, and received, from the surface of the target shapes and the material separating them. A location of at least one maxima point of the return signal is identified. Finally, a centroid is determined as the median of the locations of at least one maxima point.