19 July 2000 Fabrication process of alternating phase-shift mask for practical use
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Proceedings Volume 4066, Photomask and Next-Generation Lithography Mask Technology VII; (2000) https://doi.org/10.1117/12.392031
Event: Photomask and Next Generation Lithography Mask Technology VII, 2000, Kanagawa, Japan
Abstract
This paper presents a fabrication process of alternating phase shift mask for actual device production. The most important issue in any practical application of alternating phase shift technology is establishment of a zero-defect mask fabrication process. We developed an altPSM with good phase accuracy suitable for practical use. A total phase accuracy of +/- 1.5 degrees and phase uniformity within 2.0 degrees were achieved by the combination of a Cr/spin-on- glass (SOG)/quartz structure, improvement of shifter thickness uniformity and application of a phase adjustment technique. The disadvantages of using SOG shifters, such as the breeding of defects, were solved by improving both SOG quality and the coating process. Consequently, our proposed process can fabricate altPSM blanks that have the same quality as conventional ones. Moreover, process optimization has reduced the average number of residual shifter defects per mask was to 0.30. Conventional mask inspection systems do not provide sufficient quality assurance in an altPSM, so we had to consider a new inspection technique. The implementation of AIMS simulation for phase measurement, defect classification and printability checks of repaired regions improved the capabilities of mask quality assurance. In addition, we confirmed the effectiveness of printed wafer inspections. Our altPSM achieved satisfactory results in a trial fabrication of actual devices.
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Naoyuki Ishiwata, Takema Kobayashi, Tadahiro Yamamoto, Hideaki Hasegawa, Satoru Asai, "Fabrication process of alternating phase-shift mask for practical use", Proc. SPIE 4066, Photomask and Next-Generation Lithography Mask Technology VII, (19 July 2000); doi: 10.1117/12.392031; https://doi.org/10.1117/12.392031
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