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Wafer Edge Exposure (WEE)

Wafer Edge Exposure (WEE) is a process where photoresist at or near the edge of the wafer is exposed.  When positive photoresist is employed, the WEE tool is primarily used to permit an absolute minimum exposure width at the edge to minimize yield losses at the edge. In the case of “notch” exposure, the WEE tool is used when the wafer will be immersed in a rack-type plating system. The WEE will not only improve yield, it will also minimize precious metal waste at the plating contact regions.  When negative resist is employed, the WEE tool is used to provide a means of protecting or sealing the edge of the wafer to prevent contamination reaching the devices within the boundary of the WEE exposure path.

It is important that the exposure faithfully follows the edge of the wafer, so that the exposure means can be properly maneuvered to create the desired effect at the wafer’s edge. The S-Cubed WEE series processor does this by employing the necessary metrology to accurately map and track the wafer’s edge.

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