Effect of the Ligand Structure on Chemical Vapor Deposition of WNxCy Thin Films from Tungsten Nitrido Complexes of the Type WN(NR2)3

Abstract

Tungsten nitrido complexes of the type WN(NR2)3 [NR2 = combinations of NMe2, NEt2, NiPr2, NnPr2, NiBu2, piperidine, and azepane] were synthesized as precursors for aerosol-assisted chemical vapor deposition of WNxCy thin films. The effects of the amido substituents on precursor volatility and decomposition were evaluated experimentally and computationally. Films deposited using WN(NMe2)(NiPr2)2 as a single-source precursor were assessed as diffusion barrier materials for Cu metallized integrated circuits in terms of growth rate, surface roughness, composition, and density. In diffusion barrier tests, Cu (∼100 nm)/WNxCy (∼5 nm)/Si samples prepared from WN(NMe2)(NiPr2)2 were annealed for 30 min at 500 °C and successfully blocked Cu penetration according to four-point probe, X-ray diffraction, scanning electron microscopy etch-pit test, and high-resolution transmission electron microscopy measurements.