| 摘要 |
PURPOSE:To lessen the error in alignment and to contrive the improvement of general- purpose properties of a wafer by a method wherein the length in the X direction of the wafer and the lengths in the two Y directions of the wafer are found using a laser beam and the shift and the rotation of the wafer are controlled in such a way that the length in the X direction is the maximum and the lengths in the Y directions are equal to each other and become smaller than the length in the X direction. CONSTITUTION:The shift and the rotation of a wafer are controlled in such a way that the length in the X direction between both ends of the wafer, which is detected by first detection means 30-33 to detect both ends of the wafer 20 by scanning the wafer 20 with a first laser beam in the X direction, is the maximum and the lengths in the Y directions between both ends of the wafer, which are each detected by second and third detection means 35-41 to detect both ends of the wafer 20 by scanning the wafer with the first laser beam in the Y directions in parallel to each other, are equal to each other and become smaller than the length in the X direction. Accordingly, the wafer 20 is scanned with the first laser beam and second and third laser beams and both ends of the wafer 20 can be detected. Thereby, the detecting accuracy is increased, the error in alignment becomes small and at the same time, the general-purpose properties of the wafer are improved. |
