Lam Research Corporation
Continuous and pulsed RF plasma for etching metals

Abstract:

Methods for etching tungsten and other metal or metal-containing films using a nitrogen-containing etchant gas are provided. The methods involve exposing the film to a continuous wave (CW) plasma and switching to a pulsed plasma toward the end of the etching operation. The pulsed plasma has a lower concentration of nitrogen radicals and can mitigate the effects of nitridation on the tungsten surface. In some embodiments, subsequent deposition on etched surfaces is performed with no nucleation delay. Apparatuses for performing the methods are also provided.