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Proceedings Paper

Extension of optical lithography by mask-litho integration with computational lithography
Author(s): T. Takigawa; K. Gronlund; J. Wiley
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Paper Abstract

Wafer lithography process windows can be enlarged by using source mask co-optimization (SMO). Recently, SMO including freeform wafer scanner illumination sources has been developed. Freeform sources are generated by a programmable illumination system using a micro-mirror array or by custom Diffractive Optical Elements (DOE). The combination of freeform sources and complex masks generated by SMO show increased wafer lithography process window and reduced MEEF. Full-chip mask optimization using source optimized by SMO can generate complex masks with small variable feature size sub-resolution assist features (SRAF). These complex masks create challenges for accurate mask pattern writing and low false-defect inspection. The accuracy of the small variable-sized mask SRAF patterns is degraded by short range mask process proximity effects. To address the accuracy needed for these complex masks, we developed a highly accurate mask process correction (MPC) capability. It is also difficult to achieve low false-defect inspections of complex masks with conventional mask defect inspection systems. A printability check system, Mask Lithography Manufacturability Check (M-LMC), is developed and integrated with 199-nm high NA inspection system, NPI. M-LMC successfully identifies printable defects from all of the masses of raw defect images collected during the inspection of a complex mask. Long range mask CD uniformity errors are compensated by scanner dose control. A mask CD uniformity error map obtained by mask metrology system is used as input data to the scanner. Using this method, wafer CD uniformity is improved. As reviewed above, mask-litho integration technology with computational lithography is becoming increasingly important.

Paper Details

Date Published: 26 May 2010
PDF: 11 pages
Proc. SPIE 7748, Photomask and Next-Generation Lithography Mask Technology XVII, 77480R (26 May 2010); doi: 10.1117/12.866840
Show Author Affiliations
T. Takigawa, Brion Technologies KK (Japan)
K. Gronlund, Brion Technologies, Inc. (United States)
J. Wiley, Brion Technologies, Inc. (United States)


Published in SPIE Proceedings Vol. 7748:
Photomask and Next-Generation Lithography Mask Technology XVII
Kunihiro Hosono, Editor(s)

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