Method and system for clamping semiconductor wafers

A wafer clamping mechanism includes a clamp ring having a central opening corresponding to the geometry of a conventional semiconductor wafer. An overhang located about the opening engages the corresponding semiconductor wafer when in place on an electrode of a plasma reactor. The clamp ring is resiliently mounted on a housing which holds a second electrode. The clamp ring is automatically engaged against the wafer as the spacing between the two electrodes is adjusted to a desired gap width. A raised annular barrier on the lower electrode circumscribes the wafer and engages a mating surface on the clamp ring in order to enhance alignment of the clamp.