| 摘要 |
PURPOSE:To improve the workability of detecting wafer edge by providing a wafer edge detecting mechanism, thereby setting the scanning range of a propriety discriminating camera to the range of minimum limit for all sizes of wafers. CONSTITUTION:An X-Y stage 10 is formed of a cassette ring holder 10 for securing a wafer 11 and a stationary base 10b for securing a reference plate 12 formed with a black region 12a of the same shape as the wafer 11. They are connected integerally with a connecting rod 14, and are respectively laterally and longitudinally moved at the prescribed pitches by drive motors 15a, 15b. The motors 15a, 15b are controlled by a reflection type edge sensor 17 which supplies a drive command signal in response to the presence or absence of reflected light from the base 10b, and the propriety of a pellet 11a is discriminated by a propriety camera provided to face an upper part above a cassette ring holder. |
