Abstract: A plasma etch reactor and a related method of its operation to provide self-cleaning of its top electrode, which is subject to being coated by polymer deposits during normal operation. In one form of the invention, radio-frequency (rf) power is applied to the top electrode on a continuous basis, but at a much lower power level than that of a primary rf power source used to supply power through a lower electrode, to generate and sustain a plasma in the reactor. The small rf power applied through the top electrode is selected to be of such a level as to remove deposits from the electrode continuously, as they are formed, but without removing any significant amount of electrode material. In another form of the invention, power is applied to the top electrode periodically during cleaning periods and power supply to the lower electrode is suspended during the cleaning periods.

Abstract: Disclosed is a process for plasma etching a mask patterned dielectric film to form vias on a semiconductor wafer, so that the resulting etched structure is devoid of residues on the walls of the structure. A via is an opening through a dielectric material through which a point of contact of underlying metal with a metal film deposited over the dielectric is made. The underlying metal, when exposed to plasma, has a tendency to sputter onto the vertical wall portions of the contact via structures. The metal-containing sputtered material forms a residue that essentially cannot be removed in the subsequent photoresist stripping process typically used in semiconductor manufacturing. The plasma etch process in accordance with the invention enables removal of the sputtered metal by utilizing with the basic dielectric etch gases a gas that reacts with the metal to form volatile compounds which are readily evacuable.