| 摘要 |
PROBLEM TO BE SOLVED: To enable the position of a mark to be detected independent of the surface condition of a substrate by a method wherein the position of the mark is separately obtained corresponding to each spatial frequency component basing on photoelectric signals, and the obtained position of the mark is multiplied by a weight attendant on an amplitude change corresponding to an intensity change in a diffracted light ray of each degree and averaged. SOLUTION: A first position dataΔX1 which specifies the position of a lattice pattern MG is calculated by a detection circuit 56 basing on a relation between a level change in a first photoelectric signal and a position (or temporal reference) which serves as a relative scan reference. A second position dataΔX2 which specifies the position of the lattice pattern MG is calculated basing on a relation between a level change in a second photoelectric signal and a position (or temporal reference) which serves as a relative scan reference. The first position dataΔX1 and the second position dataΔX2 are weightedly averaged by a weighted average calculating means 60 using a first weight coefficient C1 and a second weight coefficient C2 X, and the most probable positionΔX of the lattice pattern MG is determined.
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