Accelerating EUV learning with synchrotron light: mask roughness challenges ahead

Patrick P. Naulleau; Kenneth A. Goldberg; Eric Gullikson; Iacopo Mochi; Brittany McClinton; Abbas Rastegar

doi:10.1117/12.900488

13 October 2011 Accelerating EUV learning with synchrotron light: mask roughness challenges ahead

Patrick P. Naulleau, Kenneth A. Goldberg, Eric Gullikson, Iacopo Mochi, Brittany McClinton, Abbas Rastegar

Proceedings Volume 8166, Photomask Technology 2011; 81660F (2011) https://doi.org/10.1117/12.900488
Event: SPIE Photomask Technology, 2011, Monterey, California, United States

Abstract

Despite significant progress in the commercialization of extreme ultraviolet (EUV) lithography, many important challenges remain, including in the area of masks. The issue of EUV phase roughness that can arise from either multilayer or capping layer roughness has recently garnered increasing concern. The problem with mask phase roughness is that it couples line-edge roughness (LER) through the formation of image plane speckle. The coupling from phase roughness to LER depends on many factors including roughness magnitude, roughness correlation length, illumination partial coherence, aberrations, defocus, and numerical aperture. Analysis shows that only on the order of 50 pm multilayer roughness may be tolerable at the 22-nm half-pitch node. Results also show that Atomic Force Microscopy (AFM) may not be a suitable method for measuring mask phase roughness due to its sensitivity to the surface only. Capping layer roughness is another significant concern especially given that it has been shown to increase with cleaning cycles. In this case, however, AFM does provide a reasonable metric.

Citation Download Citation

Patrick P. Naulleau, Kenneth A. Goldberg, Eric Gullikson, Iacopo Mochi, Brittany McClinton, and Abbas Rastegar "Accelerating EUV learning with synchrotron light: mask roughness challenges ahead", Proc. SPIE 8166, Photomask Technology 2011, 81660F (13 October 2011); https://doi.org/10.1117/12.900488

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