| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an optical readout method of a very small mark engraved in a very small region, which excludes additional apparatuses from the periphery of a semiconductor wafer to reduce an exclusively used space decreasing the chances that the semiconductor wafer is in touch with other materials, and moreover can detect a very small, local flat surface region quickly and accurately with a simple configuration. SOLUTION: While a mark readout optical system (102b) is set up in a high position opposed to the periphery of the semiconductor wafer W, the periphery of the semiconductor wafer W is illuminated with a higher illuminance than that for mark readout by an illuminating means (102a). Then, while the semiconductor wafer W is rotated centrally on its central axis, a partially continuing high brightness region is detected by the mark readout optical system (102b) to judge the region as a mark formation region by image processing, and then the rotation of the wafer W is stopped. After the illuminance of the illuminating means (102a) is switched to the conventional illuminance used for mark readout, the surface of the high brightness region is focused by the mark read optical system to read out the very small mark engraved in the region.</p> |
