METHOD OF MEASURING OVERLAY ERROR, INSPECTION APPARATUS, AND LITHOGRAPHIC APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide an alternative method of calculating an overlay error which reduces the effect of noise and results in a more accurate overlay error calculation.

SOLUTION: The reflected radiation from a target mark including a plurality of diffraction gratings or the like is detected by an array of pixels. The overlay error of the gratings for each pixel is detected, and an array of overlay errors is determined. Rather than simply averaging the overlay error value for all the pixels, filtering is performed. Pixels may be filtered according to the detected value of the overlay error or the detected intensity of the pixel.

COPYRIGHT: (C)2009,JPO&INPIT