Rev.Adv.Mater.Sci.(RAMS)
No 1, Vol. 8, 2004, pages 22-26

DIFFUSION BARRIER PROPERTIES OF REACTIVELY SPUTTERED W-Ti-N THIN FILMS

A.V. Kuchuk, V.P. Kladko, V.F. Machulin, A. Piotrowska, E. Kaminska, K. Golaszewska, R. Ratajczak and R. Minikayev

Abstract

Thin W-Ti-N films were deposited by reactive d.c. magnetron sputtering from a W-Ti (30 at.%) target in Ar-N2 gas mixture and tested as diffusion barrier between GaAs and Au. The films were investigated by four-point probe sheet resistance measurements, profilometry, Rutherford backscattering spectrometry, X-ray diffraction and atomic force microscopy. The physical and diffusion barrier properties of sputter-deposited W-Ti-N depend on the concentration of nitrogen in the films. We found that the film growth rate decreases with increasing ratio of the nitrogen partial pressure, while the resistivity and nitrogen content in the films increases. The W78Ti22 structure is β-W matrix seeded with fine α-Ti precipitates. For W65Ti17N18 films, the structure is a dense mixture of ultrafine crystallites of tungsten, TiN, W2N and/or Ti2N and amorphous phase. At high nitrogen concentrations N > 30 at.%, the structure is a mixed phase of W2N and TiN. The improved barrier performance of the films with additional nitrogen was due to the "stuffing" of the grain boundaries with nitrogen. The most thermally stable W65Ti17N18 thin films prevent interaction between Au and GaAs up to 750°C.

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