Abstract
To develop a simple and low-cost exposure system for the use of code mark printing, projection lithography using an optical fiber array with quasi-square fiber ends was investigated. Plastic optical fibers with a diameter of 1 mm were reshaped into quasi-squares with a size of 0.92 mm square and round corners at one end. Printed patterns onto wafers through a projection lens with a reduction ratio of 1/10 were also round at corners. To evaluate the corner roundness, square ratio S was newly defined and calculated. S was 0 when the patterns were real circles, and 1 when they were squares, respectively. It was clarified that square ratio became large at the focused positions and under the appropriate exposure dose conditions. S was always smaller than that calculated for the shape of the optical fiber. This is probably caused by the roundness of fiber corners and the lack of light irradiance homogeneity at the fiber ends.
