Patent ID: 7932998
Filing Date: 2011-04-26
Classification: G03F

Abstract:
1. An exposure apparatus comprising: an exposure light source generating light to be emitted to and through a photomask having a pattern; a projection lens for projecting the light passed through the photomask to a wafer wherein a portion of the light projected into the projection lens is diffracted by the photomask at a diffraction angle determined by a density of the pattern in the photomask; and a transmittance adjustment filter in the projection lens, wherein the transmittance adjustment filter varies the transmittance of the light diffracted by the photomask and projected into the projection lens as a function of position in the projection lens, wherein the position in the projection lens is determined by the diffraction angle, wherein the transmittance adjustment filter is selected from a plurality of transmittance adjustment filters based on a pattern density of the photomask.