Mobile electrostatic substrate holder used in making thin electronic chips, includes ring seal and nearby drainage channels to remove any fluid ingress to drain

摘要

A ring seal (13) incorporated at the edge is located close to drainage passages (12). Fluid (11) ingress at the inner edge of the ring seal (13) is led away by the passages (12) and drained away outside the substrate holder. Drainage from the region between wafer (2) and substrate holder is further enhanced by reduction of pressure, connecting to a vacuum vessel or ejector.