| 摘要 |
<p>PURPOSE:To facilitate alignment in a short time by a method wherein, when a square device is rotated, a light which is transmitted from a light emission source without being interfered by the square device is detected by a photodetector and four peak level values are obtained in one rotation and a discrepancy of the alignment is calculated from the values. CONSTITUTION:A ceramic square substrate 10 is attracted by a subchuck 12. When the discrepancy of the substrate 10 is detected, the substrate 10 is rotated by a subchuck Z-direction driving means 13, a subchuck rotating driving means 14, tweezers X-direction driving means 16 and a Y-axial direction driving means 17. A light emitting diode 18 whose emitting light is interfered on the diagonal of the substrate 10 and transmitted if the facing sides are in parallel with each other is provided near the circumference of the substrate 10 and a photodetector 19 is provided so as to face the light emitting diode 18. Thus small and big four level values are detected every one turn of the substrate by a light detecting level detecting means 22 and the difference in level is processed by a CPU 30 having built-in discrepancy calculating means 33 and comparing means 31 and each driving means is controlled so as to eliminated the difference.</p> |
