Patent ID: 6525805
Filing Date: 2003-02-25
Classification: G03B,G03F

Abstract:
An alignment system for aligning a substrate having a frontside and a backside, with the backside having alignment marks thereon, the alignment system comprising:a light source to generate light along a first axis; an imaging optical system having an imaging field and first and second ends, and arranged along a second optical axis perpendicular to the first axis and including a beam splitter arranged at an intersection of the first and second axes, wherein the first and second axes do not intersect the substrate; a movable chuck having a perimeter with a plurality of secondary optical systems arranged thereon so as to be in optical communication with the backside of the substrate and the alignment marks, the chuck movable to place the imaging optical system in optical communication with each secondary optical system; a detector arranged adjacent the first end of the imaging optical system to receive an image of the alignment marks formed by the imaging optical system, and convert the image into an electrical signal corresponding to an electronic image; and a computer system, electrically connected to the detector, and that includes pattern recognition software to process electronic images to identify and locate each alignment mark.