Patent ID: 7567423

Claim:
An electrostatic wafer holding apparatus, comprising: an electrostatic chucking pedestal configured for wafer retention thereupon, said electrostatic chucking pedestal having a plurality of gas channels formed through a top surface thereof; a bi-directional backside conduit in fluid communication with a backside of said chucking pedestal and said plurality of gas channels; said bi-directional backside conduit in fluid communication with a backside carrier gas supply line; said bi-directional backside conduit further in fluid communication with a vacuum supply line, wherein said plurality of gas channels are configured to facilitate vacuum assisted chucking of a wafer retained on said electrostatic chucking pedestal, during which vacuum assisted chucking an electrostatic chucking voltage remains applied to the electrostatic chucking pedestal, wherein the vacuum assisted chucking is implemented prior to performing a wafer processing operation for which the wafer is chucked; a mechanism for selectively coupling said bi-directional backside conduit to one of said backside carrier gas supply line and said vacuum supply line; and detection circuitry for detecting a curvature present in a wafer placed on said chucking pedestal, said detection circuitry configured to cause said bi-directional backside conduit to be decoupled from said backside carrier gas supply line and coupled to said vacuum supply line upon said detecting a curvature present in said wafer, and said detection circuitry further configured to cause said bi-directional backside conduit to be decoupled from said vacuum supply line and re-coupled to said backside carrier gas supply line upon detecting a desired pressure between said wafer and said chucking pedestal.