Abstract: An electrode clamping assembly for a plasma reaction chamber wherein processing of a single wafer can be carried out. The electrode assembly includes a support member, an electrode such as a silicon showerhead electrode in the form of a disk having uniform thickness and a clamping ring which provides a resilient clamping force pressing against the showerhead electrode. The clamping member can be a ring of elastically deformable material and the clamping member can be tightened by a plurality of elastic spaced-apart bolts such that the clamping member is compressed and provides the resilient clamping force throughout temperature cycling of the electrode assembly during wafer processing. Heat conduction between the showerhead electrode and the support member can be improved by supplying pressurized process gas to a gap therebetween. The clamping member also provides plasma confinement in an area between the electrode and the wafer being processed.