Baffled perforated shield in a plasma sputtering reactor

Abstract

A shield assembly for protecting the walls of a plasma sputter reactor from deposition while allowing high flow of processing gas into the processing space of the reactor without the plasma leaking out of the processing space. The shield assembly is particularly useful for reactive sputtering, for example, of TiN or TaN, in which large amounts of nitrogen need to flow into the chamber. The shield assembly includes a primary shield positioned inside of the chamber sidewalls and protecting the sidewalls and preferably also the bottom wall and sides of the pedestal. Multiple holes are formed in the primary shield to pass gas input through a gas inlet in the chamber walls outside of the primary shield. A baffle shield in positioned inside of the primary shield and covers the holes in the primary shield with a gap between the two shields. The baffle shield extends only partway along the primary shield so that gap communicates with the processing space of the reactor. Preferably, both the primary and baffle shield are grounded to no electric field exists in the gap. The shield assembly is particularly useful for magnetron sputter reactors in which an axial magnetic field is generated parallel to the side portions of the primary shield.