| 摘要 |
<p>PURPOSE:To enable to attain fine alignment of the wafer by a method wherein the directions of photo acceptance elements of four pieces arranged outside of the street in relation to the street are confirmed according to the outputs of the detectors, while the outputs of photo acceptance element of four pieces arranged at the center are added by two at each time corresponding to the condition of the street, and added outputs thereof are regulated. CONSTITUTION:Because the diameter D of a beam is larger than width of the street 31, reflected light 11D extending over a chip 4, the street 31 and a chip 5 can be obtained. The photo acceptance elements 13A-13D can detect reflected light 11D at the same time. The photo acceptance element 13E and 13G detect no reflected light 11D because they are positioned at the outside of the beam diameter D, while the photo acceptance elements 13F and 13H detect diffusedly reflected light according to the interface. Accordingly, when the photo acceptance elements 13E, 13G generate no output, while the elements 13F, 13H generate outputs, the photo elements 13A-13D are positioned in relation to the street 31 as shown in the figure. When the sum of the outputs of the elements 13A and 13B, and the sum of the outputs of the elements 13C and 13D are equal to each other, it indicates that the center of the street 31 and the center of reflected the reflected light 11D coincide with each other.</p> |
