This paper contains simulation results with the Siemens EDA Calibre tool and demonstrates theoretical proof that alternative mask materials bring significant gain when compared to the tantalum-based mask absorber. Firstly, we optimized the source and aerial image intensity threshold on a set of predefined clips (with SMO techniques). Secondly, we applied ILT techniques to correct for the full chip mask based on a horizontal layout of a metal logic layer on imec’s roadmap. We then compare the tantalum-based mask with the alternative masks using imaging criteria, such as DoF (depth of focus), NILS (Normalized Image log slope), EPE (edge placement error), pattern shifts through focus, process variation band, source telecentricity errors, and MEEF (mask error enhancement factor) on a variety of features in the metal logic clip to maximize the overall process window. |
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Source mask optimization
Metals
Printing
Logic
Nanoimprint lithography
Lithography
3D mask effects