4 April 2016 Aerial imaging study of the mask-induced line-width roughness of EUV lithography masks
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EUV lithography uses reflective photomasks to print features on a wafer through the formation of an aerial image. The aerial image is influenced by the mask’s substrate and pattern roughness and by photon shot noise, which collectively affect the line-width on wafer prints, with an impact on local critical dimension uniformity (LCDU). We have used SHARP, an actinic mask-imaging microscope, to study line-width roughness (LWR) in aerial images at sub-nanometer resolution. We studied the impact of photon density and the illumination partial coherence on recorded images, and found that at low coherence settings, the line-width roughness is dominated by photon noise, while at high coherence setting, the effect of speckle becomes more prominent, dominating photon noise for exposure levels of 4 photons/nm2 at threshold on the mask size.
© (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Antoine Wojdyla, Antoine Wojdyla, Alexander Donoghue, Alexander Donoghue, Markus P. Benk, Markus P. Benk, Patrick P. Naulleau, Patrick P. Naulleau, Kenneth A. Goldberg, Kenneth A. Goldberg, "Aerial imaging study of the mask-induced line-width roughness of EUV lithography masks", Proc. SPIE 9776, Extreme Ultraviolet (EUV) Lithography VII, 97760H (4 April 2016); doi: 10.1117/12.2219513; https://doi.org/10.1117/12.2219513

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