7nm node EUV predictive study of mask LER transference to wafer

The transition into smaller nodes has resulted in stringent CD tolerance requirements and the role of mask LER in that budget is not sufficiently understood. The critical variables associated with mask LER were explored with the goal of establishing mask requirements based on wafer requirements. A systematic study of the impact of mask LER correlation length ( ξ ), critical exponent ( α ) and standard deviation of the line edge ( σ ) on the printability of 7nm node line/space (L/S) and contact holes (CH) in extreme ultraviolet lithography has been simulated. An experimentally relevant range of the three mask LER variables was explored in these simulations. CDU and CER/LER were the primary metrics used to gauge printability and they were evaluated as a function of ξ, α and σ with stochastic simulations. A 45nm pitch was investigated to determine critical mask LER parameters that mark printability transition regions relevant to the 7nm node middle of line.