Patent ID: 7271908

Claim:
An apparatus for measuring alignment accuracy for measuring an alignment accuracy between an alignment mark of a lower layer and an alignment mark of an upper layer formed to each of alignment mark portions on every plural chip units or exposure units arranged on a substrate to be measured, comprising: an XY stage movable in a direction x and in a direction y while mounting the substrate; an illumination system for illuminating the alignment mark portions in a state where the XY stage moves in a direction x which is a direction of arranging the chips; a detecting system having a lens for collecting a reflection light in the moving state obtained from the alignment mark of the lower layer and the alignment mark of the upper layer on each of the alignment mark portions irradiated by the illumination system, a focusing system for focusing reflection light in the state obtained by collecting the reflection light from the lens, a scanning system for scanning reflection light image in the moving state focused by the focusing system in a direction opposite to that of the moving and an image sensor receiving reflection light image substantially in a static state being scanned in the opposite direction by the scanning system for conversion into an image signal; and an alignment accuracy calculator for measuring alignment accuracy between the alignment mark of the lower layer and the alignment mark of the upper layer at least for a direction perpendicular to the moving direction based on the image signal converted by the image sensor of the detecting system.