| 摘要 |
<p>PURPOSE: To precisely compute wafer center and orientation flat direction and to conduct alignment in a highly precise manner. CONSTITUTION: A laser beam LB for detection of positional information is positioned on an X-axis, a wafer W is rotated a turn with a P-point as the center of turn, the positional information of the outer circumference is detected for each rotating angle of two degrees, and the positional information of 18 points of A1 to F1 , A2 to F2 and A3 to F3 are selected from the above-mentioned positional informations. The center of the circle passing informations of A1 to A3 , B1 to B3 ,... and F1 to F3 in computed, the center in close vicinity to each other is selected and wafer center (Xc and Yc) is obtained. The center of circle computed from the information of the C1 to C3 other than the above-mentioned selection does not become the center of the wafer because the C1 is on the orientation flat OF. Then, the C1 is positioned on the face of laser by rotating the wafer, the wafer is moved to Y-axis direction by 6mm to left and right, and after the angle of the laser beam face of orientation flat OF has been measured, the wafer is moved to X-axis and Y-axis directions so that the wafer center is coincided with the normal center, and at the same time, the wafer is rotated in such a manner that the orientation flat direction is coincided with normal direction.</p> |
