FEEDBACK CONTROL APPLIED TO IMPROVE CONVERGENCE OF PERFORMANCE-BASED OPTICAL PROXIMITY CORRECTION IN ADVANCED LITHOGRAPHY

摘要

The continuous shrinking of VLSI critical dimensionsrn(CD) has led to increasing difficulties in nano-scale fabricationrnto transfer mask pattern onto silicon wafers. Opticalrnproximity correction (OPC) is introduced to improvernprint image fidelity. Conventional OPC aims at minimizingrnedge placement error (EPE), without considerations ofrnpost-lithography circuit performances. We have previouslyrnproposed a performance-based OPC (PB-OPC) methodologyrnwhich focuses on the circuit performance. This novelrnmethod reduces mask size significantly with little loss inrntiming accuracy. However one limitation of our approachrnis the computational time used in generating the requiredrnmask. In this paper, we make use of ideas from feedbackrncontrol to improve on the convergence speed of generatingrnthe OPC mask.