Optical inspection of NGL masks

Donald W. Pettibone; Stanley E. Stokowski

doi:10.1117/12.569366

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6 December 2004 Optical inspection of NGL masks

Donald W. Pettibone, Stanley E. Stokowski

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Proceedings Volume 5567, 24th Annual BACUS Symposium on Photomask Technology; (2004) https://doi.org/10.1117/12.569366
Event: Photomask Technology, 2004, Monterey, California, United States

Abstract

For the last five years KLA-Tencor and our joint venture partners have pursued a research program studying the ability of optical inspection tools to meet the inspection needs of possible NGL lithographies. The NGL technologies that we have studied include SCALPEL, PREVAIL, EUV lithography, and Step and Flash Imprint Lithography. We will discuss the sensitivity of the inspection tools and mask design factors that affect tool sensitivity. Most of the work has been directed towards EUV mask inspection and how to optimize the mask to facilitate inspection. Our partners have succeeded in making high contrast EUV masks ranging in contrast from 70% to 98%. Die to die and die to database inspection of EUV masks have been achieved with a sensitivity that is comparable to what can be achieved with conventional photomasks, approximately 80nm defect sensitivity. We have inspected SCALPEL masks successfully. We have found a limitation of optical inspection when applied to PREVAIL stencil masks. We have run inspections on SFIL masks in die to die, reflected light, in an effort to provide feedback to improve the masks. We have used a UV inspection system to inspect both unpatterned EUV substrates (no coatings) and blanks (with EUV multilayer coatings). These inspection results have proven useful in driving down the substrate and blank defect levels.

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Donald W. Pettibone and Stanley E. Stokowski "Optical inspection of NGL masks", Proc. SPIE 5567, 24th Annual BACUS Symposium on Photomask Technology, (6 December 2004); https://doi.org/10.1117/12.569366

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