| 摘要 |
PURPOSE:To suppress movement of an optical system member and to accurately align by providing a lattice mark on a mask, a board, and aligning the mask with the board by utilizing diffraction due to a lattice. CONSTITUTION:A beam radiated from a light source 16 is diffracted via lattices 15a, 15b of a mask 14, n-order diffracted light fed via a diaphragm is diffracted twice at concave and convex mirrors 6, 7, transmitted via the lattices 11b, 11a of a board wafer 12, and photodetected by photodetectors 19b, 19a. When a movable unit 4b is so moved via a movable unit motion controller 10 that the photodetected results become maximum, the movement of an optical member is suppressed to a very small distance based on the relative position relationship quantitatively grasped to be accurately aligned. |
