14 May 2007 Multilayer bottom topography effect on actinic mask-blank inspection signal
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Proceedings Volume 6607, Photomask and Next-Generation Lithography Mask Technology XIV; 66070K (2007) https://doi.org/10.1117/12.728934
Event: Photomask and Next-Generation Lithography Mask Technology XIV, 2007, Yokohama, Japan
Abstract
The detectability of a small phase defect on a multilayer-coated mask blank was investigated by using electromagnetic simulation. When a smoothing deposition of multilayer coating is used the inspection signal from the phase defects is characterized not only by a top surface topography of the multilayer but also by bottom topography. To understand the impact of the bottom topography we first calculated the phase shift of reflected EUV light from multilayers with various bi-layer thicknesses since the smoothing effect may be equivalent to the local multilayer thickness variation. Then, we estimated the actinic inspection signal intensity from bump, pit, line, and groove defects taking into account the phase shift due to bi-layer thickness change and the phase change due to the top surface topography. Simulation results revealed that the phase shift due to the top surface topography was enhanced by smoothing deposition for both convex and concave shaped phase defects. Thus the bump defect is detected as higher bump than the actual height of top surface and the pit defect is detected as a deeper pit than the surface depth.
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Tsuneo Terasawa, Tsuneo Terasawa, Toshihiko Tanaka, Toshihiko Tanaka, Osamu Suga, Osamu Suga, Toshihisa Tomie, Toshihisa Tomie, } "Multilayer bottom topography effect on actinic mask-blank inspection signal", Proc. SPIE 6607, Photomask and Next-Generation Lithography Mask Technology XIV, 66070K (14 May 2007); doi: 10.1117/12.728934; https://doi.org/10.1117/12.728934
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