Development of Optical System Eliminating Insensitive Regions in Linear Image Sensor Using Image Split Mirror

Abstract

In an automatic detection system for small particles on patterned wafers, the optical system which eliminates insensitive regions on a linear image sensor has been developed. The real image of wafer is splitted into two parts by the split mirror set on the real image plane of the detection system. The insensitive regions are eliminated by setting the linear image sensors whose pixels are shifted by a halfpixel relatively, on these two real images. The relative displacement between the two real image detected by the sensors is 0.5±0.1 pixel over the view field of 3mm and the shading of images is 23%. The intensity of images with the split mirror becomes twice as much as that with the half mirror.