E. Nebauer, U. Merkel, J. Würfl

Published in:

Semicond. Sci. Technol., vol. 12, no. 9, pp. 1072-1078 (1997).

Abstract:

The microstructural properties of tungsten, tungsten silicide and tungsten silicide nitride layers on GaAs were studied by thin film x-ray diffraction and correlated with deposition parameters, target composition and residual contamination during deposition. The x-ray diffractograms were used as ‘fingerprints’ for the existing phases in such contact layer/III–V semiconductor systems. It was found that in the as-deposited case of sputtered tungsten and WSi_x the β-W phase can coexist, whereas in the case of reactively sputtered WSi_xN_y no other phases were found. After a series of rapid thermal annealing treatments diffractograms were measured showing W and/or W₅Si₃ as dominating phases. The recrystallization temperatures of WSi_xN_y are found to be near 850 °C and 50 K higher than for the optimum WSi_0.45. In contrast to WSiN, the recrystallization behaviour of WSi is strongly dependent on composition and contamination.

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