Patent ID: 6744494
Filing Date: 2004-06-01
Classification: G03F

Abstract:
A mask filter for compensating light exposure on different, subsequently irradiated target areas in a photosensitive medium on a semiconductor wafer to improve an exposure dose uniformity comprising:a rectangular frame for insertion between a light source and said photosensitive medium, the rectangular frame having a transparent section around an interior perimeter of the rectangular frame; a plurality of oblong rectangular opaque blinds positioned within the transparent section of the rectangular frame, each of the oblong rectangular opaque blinds having edges parallel to sides of the frame and being rotatably mounted in the frame; a plurality of rotation shafts, each rotation shaft extending completely through a respective corresponding one of the plurality of oblong rectangular opaque blinds along a longitudinal axis thereof, each rotation shaft extending beyond the frame, wherein each of said plurality of oblong rectangular opaque blinds is rotatable around the longitudinal axis so as to define the area masked by the projection of each oblong rectangular opaque blind on the photosensitive medium and to continuously adjust a ratio between irradiated and non-irradiated areas on the photosensitive medium.