Extension of optical lithography by mask-litho integration with computational lithography

T. Takigawa; K. Gronlund; J. Wiley

doi:10.1117/12.866840

26 May 2010 Extension of optical lithography by mask-litho integration with computational lithography

T. Takigawa, K. Gronlund, J. Wiley

Proceedings Volume 7748, Photomask and Next-Generation Lithography Mask Technology XVII; 77480R (2010) https://doi.org/10.1117/12.866840
Event: Photomask and NGL Mask Technology XVII, 2010, Yokohama, Japan

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.

Citation Download Citation

T. Takigawa, K. Gronlund, and J. Wiley "Extension of optical lithography by mask-litho integration with computational lithography", Proc. SPIE 7748, Photomask and Next-Generation Lithography Mask Technology XVII, 77480R (26 May 2010); https://doi.org/10.1117/12.866840

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