| 摘要 |
PROBLEM TO BE SOLVED: To reduce the effect of measurement errors due to pixels by deciding an alignment mark position based on the positional information detected at a plurality of positions within a range corresponding to 1 pixel of a CCD camera. SOLUTION: The non-exposure light (detection light) from a light source 14 is poured on an AA mark 4 on a wafer 3 through a lens 15, a beam splitter 16, a mirror M1, and an objective lens 12, in this order. The observation image information of the AA mark 4 is imaged on an CCD camera 13 through the mirror M1, the beam splitters 16 and 20, the mirror M2, and the erector lens 21. Here, an amount corresponding to a half of the pixel of an imaging means of the CCD camera 13, as well as a positional information based on the detection signal from the CCD camera 13 at two positions with different stage, are detected respectively. Based on the positional information for detected two marks, the position of the alignment mark 4 is decided. Thus, the measurement error affected by pixels is reduced. |
