Clamped monolithic showerhead electrode

A method of replacing a showerhead electrode of a showerhead electrode assembly comprising a showerhead electrode having:

• a central portion and a peripheral portion defined by upper and lower faces of the showerhead electrode, the upper face including a planar surface extending across the central portion and part way across the peripheral portion, the upper face including an annular recess outward of the planar surface, the lower face defined by a planar inner surface extending across the central portion and a stepped outer surface extending across the peripheral portion, the stepped outer surface including an annular planar surface defining an area of increased thickness of the showerhead electrode;
• a plurality of gas outlets in the central portion of the electrode through which process gas can be delivered to a gap between the showerhead electrode and a lower electrode on which a wafer is supported;
• a plurality of circumferentially spaced apart pockets in the annular recess, the pockets configured to received cam locks therein adapted to clamp the showerhead electrode to a backing plate;
• a backing plate including axially extending bores aligned with the pockets in the showerhead electrode and radially extending bores communicating with the axially extending bores;
• rotatable camshafts mounted in the radially extending bores;
• locking pins located in the pockets in the showerhead electrode, the locking pins including enlarged heads at free ends thereof, the camshafts including cutouts adapted to engage and lock the heads of the locking pins so as to mechanically clamp the showerhead electrode to the backing plate, comprising releasing the cam locks to disengage the cam locks from the locking pins, removing the showerhead electrode, aligning locking pins of a new or refurbished showerhead electrode with the axial bores in the backing plate, and rotating the cam locks to engage the heads of the locking pins.