2 research outputs found
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<sub><i>x</i></sub> was demonstrated using
the oxo tungstenÂ(VI) fluoroalkoxide single-source precursors, WOÂ[OCCH<sub>3</sub>(CF<sub>3</sub>)<sub>2</sub>]<sub>4</sub> and WOÂ[OCÂ(CH<sub>3</sub>)<sub>2</sub>CF<sub>3</sub>]<sub>4</sub>. 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 W<sub>18</sub>O<sub>49</sub> 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)
Tungsten Nitrido Complexes as Precursors for Low Temperature Chemical Vapor Deposition of WN<sub><i>x</i></sub>C<sub><i>y</i></sub> Films as Diffusion Barriers for Cu Metallization
Tungsten
nitrido complexes of the form WNÂ(NR<sub>2</sub>)<sub>3</sub> [R =
combinations of Me, Et, <sup><i>i</i></sup>Pr, <sup><i>n</i></sup>Pr] have been synthesized as precursors for the chemical
vapor deposition of WN<sub><i>x</i></sub>C<sub><i>y</i></sub>, a material of interest for diffusion barriers in Cu-metallized
integrated circuits. These precursors bear a fully nitrogen coordinated
ligand environment and a nitrido moiety (Wî—¼N) designed to minimize
the temperature required for film deposition. Mass spectrometry and
solid state thermolysis of the precursors generated common fragments
by loss of free dialkylamines from monomeric and dimeric tungsten
species. DFT calculations on WNÂ(NMe<sub>2</sub>)<sub>3</sub> indicated
the lowest gas phase energy pathway for loss of HNMe<sub>2</sub> to
be β-H transfer following formation of a nitrido bridged dimer.
Amorphous films of WN<sub><i>x</i></sub>C<sub><i>y</i></sub> were grown from WNÂ(NMe<sub>2</sub>)<sub>3</sub> as a single
source precursor at temperatures ranging from 125 to 650 °C using
aerosol-assisted chemical vapor deposition (AACVD) with pyridine as
the solvent. Films with stoichiometry approaching W<sub>2</sub>NC
were grown between 150 and 450 °C, and films grown at 150 °C
were highly smooth, with a RMS roughness of 0.5 nm. In diffusion barrier
tests, 30 nm of film withstood Cu penetration when annealed at 500
°C for 30 min