Pattern density dependence of thermal deformation of extreme ultraviolet mask and its impact on full field lithography performance

Full field lithography performance of production extreme ultraviolet lithography (EUVL) tool has been studied when thermal deformation of mask and projection optics (PO) can not be neglected at 45 nm node. The thermal deformation of a philosophic design of EUV mask with certain local pattern density had been analyzed. The results show that thermal management is needed. The lithography performance of deformed EUVL system is degraded significantly due to the maximum pattern placement error of 5.9 nm on the wafer, consequently result in poor overlay accuracy. The results indicate that thermal deformation of system result in a tight role of system design, mask and resist technology.