| 摘要 |
PURPOSE:To construct a wafer detecting unit free of moving mechanism by a method wherein a wafer-housing carrier and a condensing lens are provided between a light-emitting section and light-receiving section. CONSTITUTION:Wafers 2 are housed in a multiplicity of accommodating stages in a carrier 1. From a light-emitting section 3, a beam-like optical flux, sufficiently smaller than a wafer 2 in thickness, is emitted to run through one end of the carrier 1, along the wafer surface, through the other end of the carrier 1, to finally reach a light-receiving section 4, after travelling through a condensing lens 7. The light-receiving surface of the light-receiving section 4 is positioned at the focus of the condensing lens 7 and all the parallel fluxes entering the lens 7 collect on the light-receiving surface of the light receiving section 4. The axis of an optical beam emitted by the light-emitting section 3 runs along the surface of a wafer 2 accommodated in the carrier 1, and the light-emitting section 3 is caused to travel for the axis to move parallel with the direction of the accumulation of the wafer stages. The scan cover the entirety of the wafer stages for the detection as to if there is a wafer present in every one of the stages and, if present, its position.
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