Effects of TaN substrate pretreatment by Ar plasma on copper chemical vapor deposition

Abstract

CVD Cu films deposited on TaN substrates with and without an Ar plasma treatment prior to Cu film deposition and the effects of postdeposition thermal annealing were investigated. Cu films deposited on an Ar-plasma-treated TaN substrate have a number of favorable properties over the films deposited on a TaN substrate without the plasma treatment. These include a smoother film surface, regular arrangement of Cu grains, and increased (111)-preferred orientation. The postdeposition thermal annealing enhanced the (111)-preferred orientation and decreased the resistivity of the as-deposited Cu films. As the results of Ar plasma substrate pretreatment, we presume that the smoother and amorphous-like surface layer of the TaN substrate enhanced the formation of the most stable (111) texture Cu films, and that the higher substrate surface energy resulted in Cu films with smoother surface and regularly shaped smaller grains. Thus, a combined process including Ar plasma substrate treatment prior to Cu film deposition and postdeposition thermal annealing at an appropriate temperature in N-2 ambient is proposed for the advantages of low-resistivity and high (111)-oriented Cu film deposition. (C) 2002 The Electrochemical Society.