Is model-based optical proximity correction ready for manufacturing? Study on 0.12- and 0.175-μm DRAM technology

Two full-chip OPC approaches, a traditional rule-based approach and a more recent model-based approach are compared on DRAM applications using both ArF and KrF lithography, with off-axis illumination and phase shift masks. The similarities and differences between these two OPC approaches are compared in detail with selected one- and two-dimensional layout situations. Our results from the model-based approach show good line width control for one- dimensional structures and improved line-end printing for two-dimensional structures; however, results also show severe process window limitations for some layouts. The cause of the process window limitations with the model-based approach are discussed. To address the process window limitations in the model-based approach, a rule-based pre- correction was used to ensure adequate process window at deviated dose and focus conditions. With pre-correction combined with the model-based approach, our wafer data shows good correction quality and process window.