| 摘要 |
By irradiating a dot mark formation surface whose center portion is protruded with light obliquely from above or from just above, its irregularly reflected light is received by a CCD camera (18) disposed just above or obliquely above the irradiation surface. Image information sent from the CCD camera (18) is subjected to image processing so as to read the dot mark as a very bright spot. Consequently, the brightest spot of the reflected light can be recognized as a dot mark formation position easily and securely for a long time with a simple image processing. Further, a gap between respective dots can be reduced as compared to the conventional ones. In case where the aforementioned mark is minute, and the mark is formed on an inner face of a notch portion or peripheral face of a semiconductor wafer (W), the marks on all the wafers (W) can be read out while the plural semiconductor wafers (W) are accommodated in the cassette (11). Consequently, it is possible to read a dot mark having a peculiar shape whose part is protruded and to secure the visibility by the dot mark reading apparatus and method. <IMAGE> |
