Characterization of pattern geometrical effect on line end shortening in x-ray lithography

Abstract

Line end shortening in x-ray proximity lithography was characterized from the viewpoint of the pattern geometry. Mask patterns from 0.1 to 0.3 mu m linewidth with different pattern density were fabricated by e-beam lithography and subsequent gold electroplating. The mask patterns were printed in commonly well known chemically amplified resists using the Satellite-800 x-ray stepper developed by Sumitomo Heavy Industry with the synchrotron storage ring at the Pohang Accelerator Laboratory at Postech. A former study [J. R. Maldonado et al., J. Vac. Sci.;Technol. B 13, 3094 (1995)] had shown the effect of the absorber thickness and the gap between mask and wafer on line end shortening. In this article, the effect on line end shortening of the geometry of a neighboring pattern, such as pattern shape, pattern density and position of the neighboring pattern, was considered. Several resists with different postexposure bake (PEB) temperatures and different gaps between mask and wafer were examined to characterize their effect on line end shortening. The closer neighboring pattern induced larger line end shortening and also higher FEB temperature and larger gap caused larger line end shortening. A perpendicular neighbor pattern to the test pattern induced different line end shortening than a parallel neighbor pattern. In addition, two dimensional aerial image simulations were performed and line end shortening was extracted from the calculated aerial image. Simulation results showed good agreement with the experimental results. (C) 1998 American Vacuum Society. [S0734-211X(98)16606-4].