| 摘要 |
PURPOSE:To enable high-accuracy position shift detection by referring to position information regarding the quantity of a position shift at right angles to an alignment direction when finding the quantity of the relative position shift between 1st and 2nd bodies. CONSTITUTION:The luminous flux from a light source 3 is collimated by a collimator lens 4 into parallel light beams, which are converged by a projection lens 5 for beam reduction which is used when necessary to optimize the spot diameter on the surface of the 1st body 1 and a 1st physical optic element provided on the surface of the 1st body 1 such as a mask is irradiated with the light beams through a bending mirror 6. Diffracted light beams of specific order from the 1st physical optic element on the 1st body 1 is made incident on a 2nd physical optic element provided on the surface of the 2nd body such as the wafer and diffracted successively, and the diffracted light beams are converted as signal light by a photodetection lens 7; and a photodetector 8 detects its center position of gravity. |
