| 摘要 |
<p>Overlay measurement equipment is provided to prevent a slider from wearing unevenly by employing a wafer stage which floats a wafer and moves the floating wafer horizontally by electromagnetic force. Overlay measurement equipment comprises a light source(110), an optical module(130), a camera(140), and a wafer stage(150). The light source generates a predetermined incident light through a power voltage applied from outside. The optical module projects the incident light from the light source to an upper surface of a wafer(120), and magnifies an overlay pattern formed on the upper surface of the wafer by using a reflection light reflected from the upper surface of the wafer. The camera acquires an image corresponding to the overlay pattern formed on the upper surface of the wafer. The wafer stage floats the wafer in the air to prevent a hunting phenomenon caused by defective images acquired by the camera by inclining the wafer to have a predetermined incidence angle about a light axis of an incident light.</p> |
