Plasma shaping plug for control of sputter etching

摘要

A re-entrant plug structure is disclosed which extends inside a processing chamber containing an ionized plasma in proximity to the plasma to physically displace the ionized plasma and selectively controllably vary concentration of ionized gas particles over the surface of a wafer to be sputter etched which is supported inside the chamber. The variation of concentration of the ionized plasma allows the selectively controllable variation of sputter etch rates on the surface of the wafer. The re-entrant plug structure may be formed as part of the enclosure cover of the processing chamber or may be a separable moveable unit which is inserted into the plasma through an opening in the processing chamber. The re-entrant plug may be of various lengths, diameters and shapes to displace and shape the ionized plasma. In an alternative embodiment of the invention, the plug contains a permanent or electromagnet which further magnetically displaces and shapes the plasma in addition to the physical displacement caused by the re-entrant plug.