TINXOY AS A BARRIER BETWEEN CR-SI-(O) AND ALUMINUM THIN-FILMS

The effect of TiN(x)O(y) barrier films (0 less-than-or-equal-to x less-than-or-equal-to 1.0; y less-than-or-equal-to 0.12) on interdiffusion and interface reaction was investigated in Cr-Si-(O)/TiN(x)O(y)/Al layered films and compared with the results for Cr-Si-(O)/Al. The film systems were deposited on Si/SiO2 substrates in a vacuum sequence using a reactive d.c. planar magnetron sputtering method. The electrical resistance and its temperature coefficient and the relative reflection coefficient (in the visible spectrum) were determined. The film systems were characterized by means of secondary ion mass spectrometry and transmission electron microscopy-transmission electron diffraction. It was found that in TiNO(y) films (y almost-equal-to 0.1) a separate TiO(y) phase is formed, which fully encloses the TiN grains. This oxidic phase has a high conductivity. It is extremely thin (1-2 nm) and, probably, amorphous. Such TiNO(y) films are stable diffusion and reaction barriers to chromium silicide films and titanium out-diffusion. However, they are not very stable barriers to aluminium interdiffusion. Aluminium films on TiNO(y) interlayers also have a tendency for aluminium migration and aluminium reconstruction. The results are discussed with reference to a simple barrier model.