Importance

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Abstract

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 that separates a process environment from an operator environment. In one orientation, a port cover plate seals an opening that pierces a bulkhead, while a door panel rests horizontally on the operator environment side of the bulkhead. In this position, a cassette of wafers may be placed on an inside surface of the door panel, with the top of the stack being open. As the door rotates to a vertical position, the wafer stack moves through the bulkhead opening thereby entering the process environment. A moveable trolley, connected to or within the door, moves parallel to the wafer stack detecting the presence of wafers by sensing light scattered from wafer edges through a window in a cover plate of the door panel. In this way the apparatus determines each wafer's location and may provide that information to subsequent wafer manufacturing operations. A movable air jet on a side of the window opposite the trolley, magnetically coupled to the trolley, moves with the trolley to clear liquid droplets or particles from the process environment side of the window.

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First Claim