| 摘要 |
<p>PURPOSE:To detect a position shift with high accuracy even if diffracted light which is diffracted differently from signal light is nearly converged on a photodetection surface by changing the position of incidence on a specific surface of 2nd luminous flux with the same magnification with 1st luminous flux about the relative position shift between a 1st and a 2nd body. CONSTITUTION:Diffraction gratings 3 and 5 are formed on a mask 1 and a wafer 2 so that pieces of 1st luminous flux 7 and 7' which are emitted by a light source and diffracted by the wafer 2 as diffraction of (n)th order and diffracted again by the mask 1 as diffraction of (l)th order shift in the position of incidence on the surface of a sensor 11 with the specific magnification of the relative position shift between the mask 1 and wafer 2, where (m), (n) and (l) are integers. At the same time, the positions of incidence on specific surface of a sensor 12 of pieces of 2nd luminous flux 8 and 8' which are diffracted by the mask 1 as diffraction of (m')th order and diffracted by the wafer 2 as diffraction of (n')th order shift is changed with the same magnification with the pieces of 1st luminous flux 7 and 7' about the relative position shift quantity between the mask 1 and wafer 2, and the relative position shift between the mask 1 and wafer 2 is detected from the incidence positions of the pieces of 1st luminous flux 7 and 7' and the pieces of luminous flux 8 and 8'.</p> |
