This study explores the relationship between EUV mask stack reflectivity and horizontal to vertical pattern bias. In this computational study, the MoSi2 thickness is varied at systematic locations in the mask stack, then data on horizontal to vertical bias (H to V bias) for multiple features are gathered. The data will be used to understand the relationship between mask substrate reflectance, mask material thickness, and H to V bias. The study will also investigate the impact of high numerical aperture (0.55 NA anamorphic) imaging on the final H to V bias. Initial work indicates that a 1% variation in substrate reflectance results in approximately a 4% variation in CD.
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Lawrence S. Melvin, Yudhishthir Kandel, Qiliang Yan, Artak Isoyan, Weimin Gao, "Extreme ultraviolet mask multilayer material variation impact on horizontal to vertical pattern bias," Proc. SPIE 10583, Extreme Ultraviolet (EUV) Lithography IX, 105831S (19 March 2018);