Effect of deposition conditions on internal stresses and microstructure of reactively sputtered tungsten nitride films

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Detail(s)

Original languageEnglish
Pages (from-to)239-246
Journal / PublicationSurface and Coatings Technology
Volume127
Issue number2-3
Publication statusPublished - 22 May 2000
Externally publishedYes

Abstract

A combined investigation of internal stress generation by in situ substrate curvature measurements during the growth of tungsten nitride (WNx) thin films and of structural properties by ex situ X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and electron energy-loss spectroscopy (EELS) is reported. It was found that the properties of the deposited films not only depended on the nitrogen partial pressure in Ar-N2 gas mixtures but also on the total sputtering-gas pressure. The stress of the films was strongly related to their microstructure, which depended mainly on the incorporation of nitrogen in the films. Annealing of as-deposited films at 600°C or above resulted in crystallization of the amorphous phases, forming either a two-phase structure consisting of W2N and b.c.c. W or a single-phase structure of W2N, which was related to the initial nitrogen concentration (CN) in the films. Cross-sectional TEM studies showed that an average column width for 150-nm-thick films near stoichiometry of W2N was ~15 nm, whereas the column grains were larger with decreasing CN. XPS results revealed that W2N had an ionic bonding character, Wδ+-Nδ-. It was also found that once the W2N phase was formed, the density, microstructure and bonding feature were similar and insensitive to the total sputtering-gas pressure used in this study. © 2000 Elsevier Science S.A.

Research Area(s)

  • Microstructure, Reactive magnetron sputtering, Stress, Thin films, Tungsten nitride