Abstract: Electrode designs for reducing the problem of non-uniform etch in large diameter substrates are presented. The electrode opposite the substrate being etched in a plasma reactor can be tailored as to its shape so as to control the uniformity of the etching across the substrate. This is achieved with a number of generally dome-shaped electrode structures including generally cone-shaped electrodes, generally pyramidally-shaped electrodes and generally hemispherically-shaped electrodes. It is believed that non-uniformity of etching is due, at least in part, to excess ion density at the center of the reactor. The dome-shaped electrodes serve to disperse the high concentration of ions from the center of the reactor out toward the periphery of the substrate and thereby even out the ion density distribution across the substrate being etched. The electrodes are useable in diode plasma reactors, triode plasma reactors and ICP plasma reactors.

Abstract: The present invention is directed to a dual frequency capacitively-coupled plasma apparatus for materials processing. According to a first aspect of the present invention, a dual frequency triode reactor includes a VHF (30-300 MHz) RF power supply capacitively coupled to an upper reactor electrode and an HF (0.1-30 MHz) RF power supply capacitively coupled to a lower reactor electrode to which the wafer is attached. The VHF power supply is used to generate and control formation of a low sheath potential, high density plasma for minimum device damage and rapid etching/deposition while the HF power supply is used to provide a DC bias to the wafer substrate. According to a second aspect of the present invention, a tailored, powered upper electrode, at least a portion of which is generally conical in shape, is employed to provide a uniform etch across the diameter of the wafer.