| 摘要 |
PURPOSE:To reduce the errors of positional detection of the mask due to a treating temperature by forming one passing hole of beams used for positioning the mask to a substrate holder and a plurality of the holes to the mask. CONSTITUTION:The beam passing holes 8' of plural number such as four are arranged symmetrically to the mask 2. In the positioning of the mask, a central section 10, which is surrounded by the four holes 8' and to which a hole is not shaped, is disposed so as to conform to the center of a circular hole 9 for passing beams formed to the substrate holder 3. According to such constitution, beams from a light source 1 are projected to photosensors 4 through the common section 11 of the holes 8' and the hole 9. In such a device, one part of beams projected to the sensors 4 is interrupted by the central section 10, the output of the sensors 4 is decreased only by the portion, and the output of the sensors 4 steeply changes. Accordingly, the intersecting point of curves indicating the output of the left and right sensors 4 downward drops, and the errors of positional detection when both curves vary are reduced. That is, the errors of positional detection of the mask due to the treating temperature are made small. |
