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Proceedings Paper

Detecting Submicron Pattern Defects On Optical Photomasks Using An Enhanced El-3 Electron-Beam Lithography Tool
Author(s): R. A. Simpson; D. E. Davis
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Paper Abstract

This paper describes techniques to detect submicron pattern defects on optical photomasks with an enhanced direct-write, electron-beam lithographic tool. EL-3 is a third generation, shaped spot, electron-beam lithography tool developed by IBM to fabricate semiconductor devices and masks. This tool is being upgraded to provide 100% inspection of optical photomasks for submicron pattern defects, which are subsequently repaired. Fixed-size overlapped spots are stepped over the mask patterns while a signal derived from the back-scattered electrons is monitored to detect pattern defects. Inspection does not require pattern recognition because the inspection scan patterns are derived from the original design data. The inspection spot is square and larger than the minimum defect to be detected, to improve throughput. A new registration technique provides the beam-to-pattern overlay required to locate submicron defects. The 'guard banding" of inspection shapes prevents mask and system tolerances from producing false alarms that would occur should the spots be mispositioned such that they only partially covered a shape being inspected. A rescanning technique eliminates noise-related false alarms and significantly improves throughput. Data is accumulated during inspection and processed offline, as required for defect repair. EL-3 will detect 0.5 um pattern defects at throughputs compatible with mask manufacturing.

Paper Details

Date Published: 13 September 1982
PDF: 11 pages
Proc. SPIE 0334, Optical Microlithography I: Technology for the Mid-1980s, (13 September 1982); doi: 10.1117/12.933581
Show Author Affiliations
R. A. Simpson, IBM General Technology Division (United States)
D. E. Davis, IBM General Technology Division (United States)

Published in SPIE Proceedings Vol. 0334:
Optical Microlithography I: Technology for the Mid-1980s
Harry L. Stover, Editor(s)

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