Patent ID: 6573993
Filing Date: 2003-06-03
Classification: G01N,H01L

Abstract:
An apparatus for the in situ alignment of a mask and a semiconductor wafer, said apparatus comprising:a moveable element for gripping a mask; a moveable platform having a mounting surface for supporting a wafer; an electromagnetic radiation source for emitting an electromagnetic radiation beam directed at said mounting surface, said electromagnetic radiation beam having a property that it will be reflected by a material layer of a wafer when mounted on said mounting surface; an electromagnetic radiation detector positioned to receive the reflected electromagnetic radiation beam and for measuring the intensity of the electromagnetic radiation beam after the electromagnetic radiation beam has been reflected from a material layer on a wafer mounted on said mounting surface; a system for moving said radiation source and detector and/or said platform such that said electromagnetic radiation beam and associated reflected beam scan an area of a wafer mounted on said mounting surface; and a device coupled to said detector for determining a change in intensity of said reflected beam when said radiation beam scans over a boundary region of a wafer mounted on said mounting surface.