Growth of WO_x from Tungsten(VI) Oxo-Fluoroalkoxide Complexes with Partially Fluorinated β-Diketonate/β-Ketoesterate Ligands: Comparison of Chemical Vapor Deposition to Aerosol-Assisted CVD

Abstract

Tungsten­(VI) oxo complexes of the type WO­(OR)3L [R = C­(CH3)2CF3, C­(CF3)2CH3, CH­(CF3)2, L = hexafluoroacetylacetonate (hfac), ethyl trifluoroacetoacetonate (etfac), acetylacetonate (acac)] bearing partially fluorinated alkoxide and/or chelating ligands were synthesized. Thermal decomposition behavior and mass spectrometry (MS) fragmentation patterns of selected examples were studied. The thermolysis products of WO­(OC­(CF3)2CH3)3(hfac) were characterized by nuclear magnetic resonance and gas chromatography–MS. Studies of the sublimation behavior of the complexes demonstrated that their volatility depends on the degree of fluorination. Comparative studies of the deposition of tungsten oxide by chemical vapor deposition (CVD) and aerosol-assisted CVD were carried out using WO­(OC­(CF3)2CH3)3(hfac) as a single-source precursor. WO x materials were successfully deposited by both deposition methods, but the deposits differed in morphology, structure, and crystallinity.

Advanced developments in nonstoichiometric tungsten oxides for electrochromic applications

“…The films deposited on a common glass display remarkable EC performance with maximum coloration efficiency of 66 cm 2 /C. Ou et al 202 synthesized tungsten (VI) Oxo-complexes of the type WO(OR) 3 L having partially fluorinated alkoxide and/or chelating ligands (Figure 6).…”

A chemist's guide to photoelectrode development for water splitting – the importance of molecular precursor design

“…Chelating alkoxide ligands can also be used to ensure monomer formation if the deposition process requires it. 210,239…”

“…206 Fluorination of alkoxide ligands is an alternative strategy reported to increase molecular volatility due to the subsequent strong repulsion between complexes from the introduction of non-bonding p electrons on fluorine, reducing intermolecular interactions. [207][208][209][210] Fluoroalkoxides are also hydrophobic, providing additional stability against hydrolysis from atmospheric moisture. 207 While fluorinated ligands are sometimes reported in SSPs for fluorine-doped materials, 211 most commonly fluorinedoped tin oxide (FTO), 212,213 it is feasible to fabricate thin films without fluorine incorporation despite using fluorinated precursors.…”

“…Chelating alkoxide ligands can also be used to ensure monomer formation if the deposition process requires it. 210,239 The high reactivity of alkoxides makes them sensitive to moisture exposure, forming clusters or metal oxide particles due to partial hydrolysis which cannot deposit in the same way as the precursors, or at all. This decreases the ease of handling and use, requiring inert conditions during synthesis and deposition.…”

Process Optimization of Via Plug Multilevel Interconnections in CMOS Logic Devices

“…Via filling processes include the W plug fill process, the Al plug fill process, and the Cu damascene fill process. In the W plug fill process, the CVD W process is applied in terms of filling [15,16]. It is essential to derive the optimum conditions of the via profile photo/etch integration process, the glue layer Ti, and the barrier metal TiN process to optimize the process.…”