摘要
Optical projection printing is quantitatively studied, using the diffracted image of two bars of equal width and space and an aspect ratio of three. Hopkins' four-dimensional integral for partially coherent imaging is used for the numerical analysis. Diffraction-limited lenses with a circular pupil are used. Constant intensity profiles in an absorptionless photoresist and nonreflective substrate are evaluated. Then the tolerances of defocus and intensity are derived using a linewidth tolerance of ±2.5 percent of the mask linewidth which varies from 0.5, 0.75, 1, 1.5, 2, to 2.5 µm. The illuminations used have σ = 0, 0.5, 0.7, 0.78, 1, 1.3, and infinity. Copyright © 1980 by The Institute of Electrical and Electronics Engineers, Inc.