The Motion-Overlap Scheme for Reducing the Time between Continuous Scans of Wafer Stage for Step-and-Scan Lithography

Abstract

During the exposure process of a step-and-scan lithography, the transitional time between continuous scans does not produce production efficiency in which no scanning occurs. To minimize the transitional time and therefore to improve the productivity we introduce the motion-overlap scheme, which inserts a step-move between the overrun phase and the phase before exposure of next field along the scanning direction for wafer stage during the continuous exposure process. The simulation results show that the motion-overlap scheme enables the total time of two continuous scans of four different exposure field sizes reduce 8.28%, 7.11%, 5.87% and 4.53%, respectively, compared with the conventional motion planning method. This indicates that the theoretical derivation of motion-overlap planning method is effective.