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8 August 1993 Multiple shifter arrays for repairing phase defects in conjugate twin-shifter phase-shift mask
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Abstract
Phase shift lithography greatly improves the resolution of optical steppers, but its practical application is degraded by phase defects arising during mask fabrication. Phase errors resulting from residues or voids in the mask shifter films cause defects by printing directly onto the wafers or by influencing the printing of adjacent patterns. The effects of optical interferences resulting from mask phase errors are analyzed by applying a simplified 2- dimensional defect model to both isolated patterns and alternating shifter arrays. Results of these analyses show the effects of asymmetric defocusing characteristics on the printability of defects and on critical dimension control of adjacent patterns. A new repair method is described using arrays of non-printable features to counteract the effects of phase defects in alternating arrays. Results of this study have been verified by evaluating the effects of programmed defects on printed wafers and by repairing patterns of conjugate twin-shifters within a new mask structure.
© (1993) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hiroshi Ohtsuka, Kazuyuki Kuwahara, and Toshio Onodera "Multiple shifter arrays for repairing phase defects in conjugate twin-shifter phase-shift mask", Proc. SPIE 1927, Optical/Laser Microlithography, (8 August 1993); https://doi.org/10.1117/12.150459
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