English: Top: EUV multilayer and absorber (purple)constituting mask pattern for imaging a line. Bottom: EUV radiation (red) reflected from the mask pattern is absorbed in the resist (amber) and substrate (brown), producing photoelectrons and secondary electrons (blue). These electrons increase the extent of chemical reactions in the resist, beyond that defined by the original light intensity pattern. As a result, a secondary electron pattern that is random in nature is superimposed on the optical image. The unwanted secondary electron exposure results in loss of resolution, observable line edge roughness and linewidth variation. Refs.: N. Felix et al., Proc. SPIE 9776, 97761O (2016); A. Saeki et al., Nanotech. 17, 1543 (2006); T. Kozawa et al., JVST B 25, 2295 (2007).