Fine-grain tungsten by chemical vapor deposition

Landingham, R.L.; Austin, Jeffrey

doi:10.1016/0022-5088(69)90161-1

Cited by 10 publications

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“…Tungsten nitride is a potentially useful material for diffusion barriers and gate electrodes in many modern electronic devices.1"5 Traditionally, tungsten nitride is prepared using techniques that employ energized particles, i.e., ion implantation, sputtering, ion-beam-assisted deposition, plasma jet spray, and plasma enhanced chemical vapor deposition.3"7 Alternatively, chemical nitridation of tungsten metal and reduction of WC16, WF6, and WO3 by NH3 at high temperatures are employed.8"11 Unlike many other transition metal nitrides, thin films of tungsten nitride are rarely grown by chemical vapor deposition (CVD). [10][11] We and others showed that organoimido complexes of transition metals can be employed as single-source precursors to grow metal nitride thin films by metallo-organic chemical vapor deposition (MOCVD).1213 Here, we report the first example of growing tungsten nitride thin films by low pressure MOCVD employing (tBuN)2W(NHtBu)2, 1, an organoimido complex of tungsten, as the single-source precursor.14…”

Section: Introductionmentioning

confidence: 93%

Tungsten nitride thin films prepared by MOCVD

Chiu

Chuang

1993

J. Mater. Res.

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Polycrystalline tungsten nitride thin films were grown by low pressure metallo-organic chemical vapor deposition (MOCVD) using (tBuN)2W(NHtBu)2 as the single-source precursor. Deposition of uniform thin films on glass and silicon substrates was carried out at temperatures 723–923 K in a cold-wall reactor, while the precursor was vaporized at 333–363 K. The growth rates were 2–10 nm/min depending on the condition employed. Bulk elemental composition of the thin films, studied by wavelength dispersive spectroscopy (WDS), is best described as WNx (x = 0.7–1.8). The N/W ratio decreased with increasing temperature of deposition. X-ray diffraction (XRD) studies showed that the films have cubic structures with the lattice parameter a = 0.414–0.418 nm. The lattice parameter decreased with decreasing N/W ratio. Stoichiometric WN thin films showed an average lattice parameter a of 0.4154 nm. X-ray photoelectron spectroscopy (XPS) showed that binding energies of the W4f7/2, W4f5/2, and N1s electrons were 33.0, 35.0, and 397.3 eV, respectively. Elemental distribution within the films, studied by secondary ion mass spectroscopy (SIMS) and Auger spectroscopy depth profilings, was uniform. The SIMS depth profiling also indicated that C and O concentrations were low in the film. Volatile products trapped at 77 K were analyzed by gas chromatography–mass spectroscopy (GC–MS) and nuclear magnetic resonance (NMR). Isobutylene, acetonitrile, hydrogen cyanide, and ammonia were detected in the condensable mixtures. Possible reaction pathways were proposed to speculate the origin of these molecules.

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Section: Introductionmentioning

confidence: 93%

Tungsten nitride thin films prepared by MOCVD

Chiu

Chuang

1993

J. Mater. Res.

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Tungsten Compounds

Penrice

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Tungsten combines with many other elements to form simple stable compounds. It readily polymerizes but the chemistry of aqueous solutions is very complex. This is exemplified by the large number of polytungstates. The chemical uses of tungsten have increased substantially in more recent years. The hexacarbonyl has potential as a lubricant additive and as a dye and pigment. The halides are useful as a starting materials in the chemical vapor deposition of tungsten. The oxides are important intermediate products in the stepwise reduction in hydrogen to the metal. Tungsten bronzes constitute a series of well‐defined nonstoichiometric compounds. The sodium tungsten bronzes are interesting not only for their intense color range but exhibit both positive and negative coefficient of resistance as the sodium:tungsten ratio changes. Sodium tungsten bronzes help the catalytic oxidation of carbon monoxide and reformer gas in fuel cells. The tungstates are an important class of materials. The metatungstates are important starting materials for production of tungsten catalysts because of the high solubility in water. Ammonium paratungstate is the intermediate material of choice between chemical recovery from ores and the reduction to tungsten metal. The interstitial compounds, particularly with carbon, represent the largest application for tungsten in cemented carbides. Tungsten compounds, especially the oxides, sulphides, and heteropoly complexes, form stable catalysts for a variety of chemical processes in the petroleum industry and in chemical synthesis. Other uses include fireproofing of textiles, as additives in lubricants and antifreeze solutions, in inks and dyes, as phosphors in fluorescent lights, and for improvement of conductivity of tin oxide coatings on aircraft windows. Because soluble tungsten compounds show varying degrees of toxicity, exposures in the workplace are regulated.

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Tungsten Compounds

Penrice

2001

Kirk-Othmer Encyclopedia of Chemical Technology

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Tungsten combines with many other elements to form simple stable compounds. It readily polymerizes but the chemistry of aqueous solutions is very complex. This is exemplified by the large number of polytungstates. The chemical uses of tungsten have increased substantially in more recent years. The hexacarbonyl has potential as a lubricant additive and as a dye and pigment. The halides are useful as starting materials in the chemical vapor deposition of tungsten. The oxides are important intermediate products in the stepwise reduction in hydrogen to the metal. Tungsten bronzes constitute a series of well‐defined nonstoichiometric compounds. The sodium tungsten bronzes are interesting not only for their intense color range but exhibit both positive and negative coefficient of resistance as the sodium:tungsten ratio changes. Sodium tungsten bronzes help the catalytic oxidation of carbon monoxide and reformer gas in fuel cells. The tungstates are an important class of materials. The metatungstates are important starting materials for production of tungsten catalysts because of the high solubility in water. Ammonium paratungstate is the intermediate material of choice between chemical recovery from ores and the reduction to tungsten metal. The interstitial compounds, particularly with carbon, represent the largest application for tungsten in cemented carbides. Tungsten compounds, especially the oxides, sulphides, and heteropoly complexes, form stable catalysts for a variety of chemical processes in the petroleum industry and in chemical synthesis. Other uses include fireproofing of textiles, as additives in lubricants and antifreeze solutions, in inks and dyes, as phosphors in fluorescent lights, and for improvement of conductivity of tin oxide coatings on aircraft windows. Because soluble tungsten compounds show varying degrees of toxicity, exposures in the workplace are regulated.

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Fine-grain tungsten by chemical vapor deposition

Cited by 10 publications

References 1 publication

Tungsten nitride thin films prepared by MOCVD

Tungsten nitride thin films prepared by MOCVD

Tungsten Compounds

Tungsten Compounds

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