Patent ID: 8484846

Claim:
A method of joining components for a composite showerhead electrode assembly for a plasma processing apparatus, comprising: applying an interface gel to a top surface of an electrode plate in a predetermined pattern within bridging regions, the electrode plate having a plasma exposed bottom surface and a plurality of gas passages extending between the top surface and the bottom surface and having inlets in unbridged regions; aligning a bottom surface of a backing plate with the top surface of the electrode plate, the backing plate having a top surface and a plurality of gas passages extending between the top surface and the bottom surface having outlets in unbridged regions; and attaching the top surface of the electrode plate to the bottom surface of the backing plate with a clamp or adhesive bond, wherein the interface gel is spread laterally into bridging regions between the top surface of the electrode plate and the bottom surface of the backing plate without bonding the electrode plate to the backing plate and the interface gel remains a gel and the gas passages of the backing plate are in fluid communication with the gas passages of the electrode plate.