Solid-phase reactions at the interface between Al-Si-Cu alloys and reactively sputtered TiN thin films were investigated by means of cross-sectional transmission electron microscopy, Auger electron spectroscopy and X-ray diffraction. When the internal stress in the TiN film was highly compressive (209MPa), a very thin amorphous Al-Ti-Si ternary compound layer, which contained micro-crystallites that were about 4nm thick, formed at the interface during annealing (450C, 0.5h). In the case of a minimal compressive stress (21MPa), a non-uniform polycrystalline Al3Ti layer formed on the amorphous intermediate layer. The behavior of the internal stress in the latter case exhibited non-linear characteristics as a function of the heating and cooling temperatures. This suggested that rearrangement of the TiN film occurred even at temperatures below 300C. Monte Carlo simulations which were based upon a ballistic aggregation model indicated that a short migration length, corresponding to low internal stress conditions, produced numerous vacancies and disordered regions in the TiN films. It was proposed that rearrangement of the films, via the diffusion of Ti atoms, governed solid-phase reaction at the Al-Si-Cu/TiN interfaces.

T.Yamauchi, T.Yamaoka, K.Yashiro, S.Sobue: Journal of Applied Physics, 1995, 78[4], 2385-91