A new synchronization control method of wafer and reticle stage in step and scan lithographic equipment

Quality of exposures in step and scan lithographic equipment (scanner) highly depends on the synchronization of wafer and reticle stage. In order to increase the synchronization between the two stages, a method of increasing the correlation through reducing the phase difference between the tracking errors of the two stages is presented. Theoretical analysis with respect to application of increasing the correlation coefficients is performed. Validation of this process is verified through simulation and the results indicate that the moving average (MA) and moving standard deviation (MSD) of the synchronization error can be reduced effectively through our method.