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Issue 11, 2007
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A low valent metalorganic precursor for the growth of tungsten nitride thin films by atomic layer deposition

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Abstract

The atomic layer deposition growth of tungsten nitride films was demonstrated using the precursors W2(NMe2)6 and ammonia with substrate temperatures between 150 and 250 °C. At 180 °C, surface saturative growth was achieved with W2(NMe2)6 pulse lengths of ≥2.0 s. The growth rates were between 0.74 and 0.81 Å cycle−1 at substrate temperatures between 180 and 210 °C. Growth rates of 0.57 and 0.96 Å cycle−1 were observed at 150 and 220 °C, respectively. In a series of films deposited at 180 °C, the film thicknesses varied linearly with the number of deposition cycles. Films grown at 180 and 210 °C exhibited resistivity values between 810 and 4600 μΩ cm. Time-of-flight elastic recoil detection analysis on tungsten nitride films containing a protective AlN overlayer demonstrated slightly nitrogen-rich films relative to W2N, with compositions of W1.0N0.82C0.13O0.26H0.33 at 150 °C, W1.0N0.74C0.20O0.33H0.28 at 180 °C, and W1.0N0.82C0.33O0.18H0.23 at 210 °C. In the absence of an AlN overlayer, the oxygen and hydrogen levels were much higher, suggesting that the films degrade in the presence of ambient atmosphere. The as-deposited films were amorphous. Amorphous films containing a protective AlN overlayer were annealed to 600–800 °C under a nitrogen atmosphere. X-Ray diffraction patterns suggested that crystallization does not occur at or below 800 °C. Similar annealing of films that did not contain the AlN overlayer afforded X-ray diffraction patterns that were consistent with orthorhombic WO3. Atomic force microscopy showed root-mean-square surface roughnesses of 0.9, 0.8, and 0.7 nm for films deposited at 150, 180, and 210 °C, respectively.

Graphical abstract: A low valent metalorganic precursor for the growth of tungsten nitride thin films by atomic layer deposition

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Publication details

The article was received on 28 Jul 2006, accepted on 06 Dec 2006 and first published on 02 Jan 2007


Article type: Paper
DOI: 10.1039/B610873C
Citation: J. Mater. Chem., 2007,17, 1109-1116
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    A low valent metalorganic precursor for the growth of tungsten nitride thin films by atomic layer deposition

    C. L. Dezelah, O. M. El-Kadri, K. Kukli, K. Arstila, R. J. Baird, J. Lu, L. Niinistö and C. H. Winter, J. Mater. Chem., 2007, 17, 1109
    DOI: 10.1039/B610873C

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