Importance

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Abstract

The present invention relates to a non-contact holder for substantially planar workpieces, particularly suited for holding thin workpieces without substantial distortion. The present invention includes a cylindrical chuck having a gas inlet orifice positioned at an oblique. The introduction of pressurized gas creates a vortex and vacuum attraction holding a wafer in close proximity to the chuck while the gas exiting from the chuck prevents contact between wafer and chuck. Small diameter chucks located in close proximity help the present invention avoid distortion when processing very thin workpieces. The gas exiting from the chuck of the present invention exits preferentially in a certain angular direction. Chucks are arranged on the wafer holder such that exiting gas is preferentially directed radially towards the periphery of the holder and that exiting gas is directed between adjacent chucks, not directly at another nearby chuck. Chucks on the periphery of the holder are positioned have the gas exiting therefrom towards the periphery of the holder and overlapping the gas flow from immediately adjacent chucks. Chucks on the periphery of the holder are located as close together as feasible. The combination of overlapping gas flow and close proximity creates a gas shield on the boundary of the wafer holder.

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First Claim