CPC H01L 21/6838 (2013.01) [B23B 31/307 (2013.01); F25B 9/14 (2013.01)] | 9 Claims |
1. A chuck comprising:
a chuck surface;
a plurality of cell groups, each cell group comprising:
a plurality of cells distributed over the chuck surface, each of the plurality of cells comprising:
at least one vacuum port, wherein each of the at least one vacuum ports is open to a conduit of a plurality of conduits that are connectable to a suction source that is operable to apply suction to that vacuum port;
and
at least one flow restrictor located within each conduit of the plurality of conduits and characterized by a flow resistance, wherein a flow resistance of each of the at least one flow restrictor in at least one conduit of the plurality of conduits connected to a cell group is less than a flow resistance of a flow restrictor in at least one other conduit of the plurality of conduits connected to another cell group.
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