Aerosol-Assisted Chemical Vapor Deposition of Tungsten Oxide Films and Nanorods from Oxo Tungsten(VI) Fluoroalkoxide Precursors

Aerosol-assisted chemical vapor deposition (AACVD) of WO_<i>x</i> was demonstrated using the oxo tungsten­(VI) fluoroalkoxide single-source precursors, WO­[OCCH₃(CF₃)₂]₄ and WO­[OC­(CH₃)₂CF₃]₄. Substoichiometric amorphous tungsten oxide thin films were grown on indium tin oxide (ITO) substrates in nitrogen at low deposition temperature (100–250 °C). At growth temperatures above 300 °C, the W₁₈O₄₉ monoclinic crystalline phase was observed. The surface morphology and roughness, visible light transmittance, electrical conductivity, and work function of the tungsten oxide materials are reported. The solvent and carrier gas minimally affected surface morphology and composition at low deposition temperature; however, material crystallinity varied with solvent choice at higher temperatures. The work function of the tungsten oxide thin films grown between 150 and 250 °C was determined to be in the range 5.0 to 5.7 eV, according to ultraviolet photoelectron spectroscopy (UPS)

Effect of the Ligand Structure on Chemical Vapor Deposition of WN_<i>x</i>C_<i>y</i> Thin Films from Tungsten Nitrido Complexes of the Type WN(NR₂)₃

Tungsten nitrido complexes of the type WN­(NR₂)₃ [NR₂ = combinations of NMe₂, NEt₂, N^<i>i</i>Pr₂, N^<i>n</i>Pr₂, N^<i>i</i>Bu₂, piperidine, and azepane] were synthesized as precursors for aerosol-assisted chemical vapor deposition of WN_<i>x</i>C_<i>y</i> thin films. The effects of the amido substituents on precursor volatility and decomposition were evaluated experimentally and computationally. Films deposited using WN­(NMe₂)­(N^<i>i</i>Pr₂)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)/WN_<i>x</i>C_<i>y</i> (∼5 nm)/Si samples prepared from WN­(NMe₂)­(N^<i>i</i>Pr₂)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