| 摘要 |
An apparatus for determining the presence or absence of wafers in a cassette, i.e. a wafer mapper, is integrated with a door assembly in a load port interface separating a process environment from an operator environment. A port cover plate and a door are arranged in an L-shape, with both members being able to seal the port in a bulkhead of the load port interface. In one configuration, the port cover plate seals the port, while door panel members rest horizontally on the operator side of the bulkhead. In this position, a wafer stack inside of a cassette may be placed on the inside door panel, with the top of the stack being open. As the door is raised from the horizontal position to a vertical position, the wafer stack is rotated through an opening in the bulkhead so that the wafer stack is now on the process side. The wafer mapper features a moveable trolley connected to, or within, the door. The trolley can move parallel to the wafer stack under control of a stepper motor and examine each row of the stack, counting wafers as light is reflected for scattered from the edges of the wafers. Each wafer may be optically probed through a window in a cover plate and characteristic signals may be plotted to provide subsequent wafer manufacturing operations with wafer locations. A movable air jet on a side of the window opposite the trolley is magnetically coupled to the trolley and is moved together with the trolley in order to clear the window of liquid droplets or particles from the process environment.
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