| 摘要 |
<p>PURPOSE:To improve the detection accuracy of the position of an orientation flat by a method wherein an error of the defocus of the outer edge image of the outer edge of a semiconductor wafer is minimized. CONSTITUTION:While a wafer chuck 12 with a semiconductor wafer 1 placed thereon is rotated, a projection beam P which from a light-emitting element 9 is projected onto the outer edge of the above wafer 1. A Z-axis correction actuator 18 is driven in such a way that an outer edge image, which is generated by this illumination, is formed on a line sensor 13 to move a projection optical system 11 and in a state that the above outer edge image is formed, an output signal from the above sensor 13 is led in by a signal processing part 22 to determine the coordinated of the points on the edge of the wafer 1 in correspondence to the angle of rotation and the position of an orientation flat is detected from the change in the coordinates of points on the edge.</p> |
