Patent ID: 6853451
Filing Date: 2005-02-08
Classification: G03F

Abstract:
1. An alignment system of a semiconductor exposure apparatus, comprising: a light source; a wafer stage dedicated to support a wafer; a beam transfer having optical elements that direct light from the light source towards the wafer stage, whereby the light can impinge an alignment mark on a wafer supported on the stage; a reticle bearing an alignment mark; a projection lens optically interposed between said reticle and said wafer stage, whereby the lens will project light reflected from the alignment mark of a wafer supported on the stage through the reticle; and an alignment detector positioned in the system to receive the reflected light projected through the reticle by the projection lens, said detector including a diaphragm having a plurality of holes through which light from the reticle can pass, sensing means for sensing secondary or higher order beams generated by light reflected through the alignment mark of the reticle, and a quadrant optical sensor positioned to receive the light that passes through the diaphragm.