Large-Area Optical Proximity Correction with a Combination of Rule-Based and Simulation-Based Methods

Abstract

We have developed a practical one-dimensional (1D) optical proximity correction (OPC) system based on a combination method. Our OPC system integrates a rule-based and a simulation-based method so that correction time can be reduced to a minimum, while maintaining sufficient accuracy for the correction. The correction accuracy depends on a simulator implemented in the system. By incorporating the 1D context within the range of the proximity effect into the rule table, higher accuracy in the OPC is obtained as compared with conventional methods which involve looking up tables based on duty ratio, or distance to the nearest neighbor. We applied this system to the linewidth correction of 0.3-µm rule logic gates, and obtained width specifications within ±10% and DOF ±0.4 µm. Since correction is basically carried out at the speed of a rule-based correction, our OPC method is applicable to large area layouts. The correction time for a layout of 116 mm2 was only 64.2 min. The results of OPC for real devices such as SRAMs and DRAMs are also given, demonstrating the feasibility of large-area 1D OPC.