| 摘要 |
PURPOSE:To allow correct calculation-of the amount of positional shift even if the measuring position of an alignment mark is shifted by one half or more of the grating width by subjecting the positional shift detection error of the alignment mark in the form of a diffraction grating, to be measured through interference with a reference grating, to correction corresponding to the grating width. CONSTITUTION:A positional shift detection error occurring when the shift of an alignment mark 5, comprising a diffraction grating formed on a water 4, is measured through interference with a reference grating 2 is eliminated by performing correction corresponding to the grating width (d). Detector output values DELTAx' corresponding to a plurality of alignment marks 5 on the wafer 4 are preserved, for example, and a decision is made that the mark 5 is shifted by one half of the grating width (d) or more based on the detector output value DELTAx'. When the mark 5 is shifted by one half of the grating width (d) or more, a value (n) is predicted for the detector output value DELTAx' thereof and the grating width (d) is corrected by an amount (nd) thus eliminating the positional shift detection error. |
