Electrostatic clamping method and apparatus for dielectric workpieces in vacuum processors

A dielectric workpiece is clamped to a holder in a vacuum plasma processor chamber by applying the plasma to a surface of the workpiece exposed to the plasma simultaneously with applying a relatively high voltage to an electrode on the holder. The electrode is in close proximity to a portion of the workpiece not exposed to the plasma so (1) the electrode is at a voltage substantially different from the plasma, (2) electrostatic charge is applied to the exposed surface by the plasma, and (3) an electrical conducting path is provided via the plasma from the electrostatic charge to a terminal at a potential substantially different from the voltage applied to the electrode. Sufficient electrostatic clamping force is applied through the thickness of the workpiece by a voltage difference between the DC voltage applied to a single electrode and charge applied by the plasma to the exposed face to hold the substrate on the holder.