Patent ID: 6153886
Filing Date: 2000-11-28
Classification: G03F

Abstract:
An alignment apparatus, which is set in an exposure apparatus having a projection optical system for projecting a projection pattern formed on a mask onto a substrate under exposure light and which performs relative alignment between said mask and said substrate, comprising:alignment light irradiating system for forming a pair of two beams from each of light beams of plural wavelengths different from that of said exposure light to obtain a plural sets of beam pairs and irradiating the plural sets of beam pairs through said projection optical system onto a specific alignment mark on said substrate;a plurality of chromatic aberration correction optical elements set in optical paths of said plural sets of beam pairs and on or near a Fourier transform plane of said projection pattern formed on said mask in said projection optical system, for deflecting said beam pairs so as to make two beams in each beam pair incident at substantially equal incident angles into said specific alignment mark;photoelectric detector for receiving beams of diffracted light which emerge in a substantially same direction from said specific alignment mark upon irradiation of said plural sets of beam pairs, to generate a signal corresponding to the diffracted light; andcontroller for controlling the relative alignment between said mask and said substrate, based on said signal from said photoelectric detector.