Hierarchical processing for accurate optical proximity correction for 1-Gb DRAM metal layers

Abstract

We propose a high-performance hierarchical mask data processing system which incorporates a refined 1D optical proximity correction (OPC) method. Using an engineering workstation, the system incorporating the refined 1D OPC, corrected the metal layer in a miniature model of a 1-Gbit DRAM within a practical time. Well-designed hierarchical management in the mask data conversion system reduced the correction time to about 1/12 of that in flat processing. Data volume expansion was suppressed within four percent compared to the mask data volume without OPC. Using both exposure experiment and lithography simulation, the correction accuracy was examined when the system was applied to test patterns of metal layer. In the case of 0.16 micrometers design rule, the range of linewidth error with refined 1D OPC was reduced to 62 nm compared to 99 nm with the conventional 1D OPC method. The proposed method is expected to achieve precise correction compared to conventional 1D OPC method. These rules suggest that the proposed OPC system is useful for correction of 1-Gbit DRAM and beyond.