Patent ID: 6052193
Filing Date: 2000-04-18
Classification: G01D,H01L

Abstract:
A wafer loading-state inspection apparatus comprising:a wafer sensor support having first and second spaced apart arms extending in a horizontal plane substantially parallel to one another;a transmissive wafer sensor comprising a light emitter supported on said first arm and a light detector supported on said second arm and spaced apart from each other in said horizontal plane by a predetermined separation distance, said light emitter and said light detector oriented to face each other along a line intersecting the arms of said wafer sensor support at acute angles, respectively, whereby light from said light emitter propagates in said horizontal plane towards said light detector diagonally across a space defined between the parallel arms of said wafer sensor support, and the wafer sensor generating wafer pulses indicating whether a wafer is detected between the light emitter and the light detector;a post oriented vertically and connected at one end to the wafer sensor support; anda driving mechanism connected to an opposite end of the post, for producing reciprocating vertical movement of the post over a vertical range.