Considering MEEF in Inverse Lithography Technology (ILT) andSource Mask Optimization (SMO)

摘要

Mask Error Enhancement Factor (MEEF) plays an increasingly important role in the DFM and RET flow required tocontinue shrinking designs in the low-k1 lithography regime. The ability to model and minimize MEEF duringlithography optimization and RET application is essential to obtain a usable process window (PW). In InverseLithography Technology (ILT), MEEF can be included in the cost function as a nonlinear factor, so that the inversionminimizes MEEF, in addition to optimizing PW and edge placement error (EPE). ILT has been shown to optimizemasks for a given source. Using ILT for contemporaneous Source and Mask co-Optimization (SMO) can provide furtherbenefit by balancing the complexity of mask and source. Results demonstrating the benefits of "MEEF-aware" ILT andSMO for advanced technology nodes are presented in this paper.