Fortrend Engineering Corporation

Torben J H Ulander

Kenneth Alan Hardy

Cyril M Kindt

Eric Meyhofer

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.

Load port door assembly with integrated wafer mapper

A wafer support featuring a polymer rack formed of parallel, spaced apart comb structures with spaced apart teeth into which wafers can loosely fit and a shank immediately below the teeth which is connected to lifter shafts. A conductive polymer bus bar runs along the shank less than a millimeter below the base of the teeth. The polymer rack will fit through a standard size wafer cassette for wafer transfer. The bus bar is connected to electrical ground, found at metal lifter shafts, by means of conductive polymer cross bars. The bus bar is close enough to one or more wafers to allow arcing from the wafer to the bus bar and then to ground when a wafer becomes highly charged with electrostatic charge, thereby discharging the wafer.

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Sunnyvale, CA, United States of America

Torben J H Ulander