Electroless Copper Deposition on H2 Plasma-Treated TaNx (x=0–1) Diffusion Barriers

Abstract

Copper was electrolessly deposited on H2 plasma treated TaN diffusion barriers for multilevel interconnect metallization to enhance the quality of electroless Cu with the low electrical resistivity of TaNx barrier films. The electrical resistivity of the H2 plasma treated TaNx barriers increased by 5.2%, compared with the TaNx barriers without plasma treatment. SIMS depth profiles of H2 in TaNx barriers showed that a small fraction (around 15%) of the depth of the TaNx barriers is shown to be plasma-treated. The density of palladium nuclei on the TaNx barriers was remarkably increased by H2 plasma treatment. Thus, improvement of the electroless copper deposition on the TaNx barriers was obtained by H2 plasma treatment without a large increase in the electrical resistivity. The surface energy of the TaNx barriers increased by 29.2% after the plasma treatment. The nucleation sites for palladium nuclei were thought to increase with increasing the surface energy.