ROLE OF ETCH PATTERN FIDELITY IN THE PRINTING OF OPTICAL PROXIMITY CORRECTED PHOTOMASKS

Optical proximity effect correction has been proven to improve critica l dimension control, increase overlay margins, and, when used with pha se-shifting masks and/or modified illumination and mask-plane nonprint ing assist features, also extend resolution and increase depth of focu s of current generation lithographic exposure technology. While the po tential enhancements afforded by such schemes are enticing, their succ essful implementation is imposing demands on mask fabrication, inspect ion, and repair which surpass the state of the art in industry today. This article focuses on the influence of the mask pattern fidelity on the ensuing wafer lithographic performance. Both wet and dry etch tech niques were applied to an ensemble of proximity-corrected test pattern s using standard binary chrome-on-glass test masks. The chrome was wet etched with polybutene sulfone as the masking resist using an optimiz ed zero-bias process. For comparison, the same test structures delinea ted with a silicon containing resist were also reactive ion etched wit h Cl-2/O-2/N-2 chemistry, developed to retain submicron pattern fideli ty, and anisotropic absorber wall profile. Comparative wet and dry-etc hed mask and resulting wafer metrology results are presented for 5 X i -line and 4 X deep ultraviolet exposures. (C) 1995 American Vacuum Soc iety.