| 摘要 |
PURPOSE:To obtain sufficient information of a wafer mark by introducing one small reflecting member of the degree which does not affect its resolution to the pupil position of a projection lens, and producing scattered lights of wafer marks at least two different positions on a wafer in a planar direction perpendicular to the optical axis of a projection lens by the member. CONSTITUTION:When a stage 1 for placing a wafer 2 is moved and a wafer mark 3 is moved on a focused spot, a diffracted scattered light is generated from the edge of the mark 3, the scattered light is deflected by a small reflector 17 obliquely provided at the center of the pupil position of a projection lens 4, and condensed through an opening window 18 by relay lens systems 19, 20 on a detector 21. Two X- and Y-axis measuring opening marks 6, 6' are focused on the marks 3, 3'. The scattered light from the edges of the marks 3, 3' are so reflected as to separate in different directions in a plane perpendicular to the optical axis of the lens 4. That is, the scattered light from the edge of the mark 3 is obtained from the window 18, and the scattered light from the edge of the mark 3' is obtained form a diffraction window 18'.
|
