Low temperature chemical vapor deposition of tungsten carbide for copper diffusion barriers

Tungsten carbide films were grown by chemical vapor deposition using W(CO) 6 and C 2H 4 between 250 and 450°C. Pyrolysis studies indicate W(CO) 6 thermally decomposes over the 150–200°C temperature range with or without ethylene. Carbon incorporation increased from 13 to ∼33% when C 2H 4 was co-fed...

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Bibliographic Details
Published in:Thin solid films 2001-10, Vol.397 (1), p.109-115
Main Authors: Sun, Y.-M, Lee, S.Y, Lemonds, A.M, Engbrecht, E.R, Veldman, S, Lozano, J, White, J.M, Ekerdt, J.G, Emesh, I, Pfeifer, K
Format: Article
Language:English
Subjects:
Applied sciences
Barrier, diffusion
Carbides
Chemical vapor deposition
Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.)
Cross-disciplinary physics: materials science
rheology
Electronics
Exact sciences and technology
Materials science
Metallization, contacts, interconnects
device isolation
Methods of deposition of films and coatings
film growth and epitaxy
Microelectronic fabrication (materials and surfaces technology)
Physics
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Tungsten
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Summary:Tungsten carbide films were grown by chemical vapor deposition using W(CO) 6 and C 2H 4 between 250 and 450°C. Pyrolysis studies indicate W(CO) 6 thermally decomposes over the 150–200°C temperature range with or without ethylene. Carbon incorporation increased from 13 to ∼33% when C 2H 4 was co-fed with W(CO) 6. The W/C carbon ratio, as established by X-ray photoelectron spectroscopy (XPS), remained approximately 2:1 regardless of the C 2H 4 to W(CO) 6 flow ratio for temperatures between 250° and 450°C. Films (50 nm thick) grown at 290°C have a resistivity of 250 μΩ-cm. Above 500°C, the W/C ratio decreased to ∼1:1.25 and the resistivity increased to 535 μΩ-cm. The tungsten and carbon are present in the tungsten carbide chemical state. X-Ray diffraction, XPS, selected area electron diffraction and transmission electron microscopy analysis reveal the films are a mixture of 5–6 nm W 2C crystallites in an amorphous matrix, whose stoichiometry is ∼2:1 W/C. Copper was not found to diffuse through 7-nm-thick tungsten carbide films in Cu/WC/SiO 2 stacks that were annealed at 400°C for 8–9 h.
ISSN:0040-6090
1879-2731
DOI:10.1016/S0040-6090(01)01367-0