| 摘要 |
PURPOSE:To improve the yield of a wafer by providing a rotary wheel and a light switch in a shallow groove of a stage of a cassette mount, thereby always maintaining the facet direction of the wafer loaded in the cassette constant. CONSTITUTION:A wafer 1 placed on a conveyor belt 12 is not dropped to a groove 13 dug smaller than the diameter of the wafer 1, but supported at opposite ends on a stage 8. Since a light from a light emitting element 10 arrives at a photoreceptor 11 in this state, a rotary wheel 9 rotates, and the wafer 1 also rotates. While the wafer 1 is rotating, when a facet 2 moves along the surface of the edge 14 of the stage 8, one side of the wafer 1 is dropped to the groove 13, the light from the element 10 is interrupted by the wafer 1 and not arrived at the photoreceptor 11. Accordingly, the wheel 9 stop rotating here. A cassette 5 is raised by one slit in the state that the wafer 1 stops rotating, the wafer 1 is contained between the slits, and the lower slits are raised at both sides of the stage 8. |
