Method for evaluating alignment accuracy

TL;DR: In this article, a reticle and a wafer are aligned by the die by die system using the TTR-system alignment optical system, and the position of the reticle stage at that time is measured by a laser interferometer.

Abstract: PURPOSE: To evaluate alignment accuracy by such statistical method as the EGA method by an exposure device for performing alignment with a die by die system using a TTR-system alignment sensor. CONSTITUTION: A reticle and a wafer are aligned by the die by die system using the TTR-system alignment optical system and the position of a reticle stage at that time is measured by a laser interferometer (Step 106). An alignment is made to K shot regions at the total shot regions on the wafer (Step 108) and the arrangement coordinates of the wafer are calculated in the EGA system based on the measurement value of a laser interferometer regarding the K shot regions and the arrangement coordinates when designing the wafer (Step 109). A minimum residual error ΔEMM, a degree of wafer cross W, and signal intensities AXn and AYn from the alignment optical system which were obtained at the time of the calculation are evaluated to evaluate alignment accuracy (Step 110).