STRESS AND ANISOTROPY EFFECTS IN THE INTERFACIAL REACTIONS OF AL AND TINX

Structural and compositional analyses of the interfacial region betwee n sputtered TiN(x) (x almost-equal-to 1) and Al films were carried out using X-ray diffraction, transmission electron microscopy, Auger elec tron spectroscopy and secondary ion mass spectroscopy. It was found th at the as-deposited TiN(x) layers, strongly textured along the [111] d irection perpendicular to the film surface, were expanded along this d irection, with an interplanar spacing larger than that for bulk TiN. T his elongation was dependent on the N2/Ar ratio in the gas phase durin g the film deposition. The TiN(x) film deformation decreased during th e subsequent heat treatments. For films with a smaller N2/Ar ratio (ex cess of Ti), a higher reactivity with Al resulting in Ti aluminides wa s noted. Another result of this study was an anisotropy of the interfa cial processes (interdiffusion and compound formation) as a function o f the layer deposition sequences. The Al/TiN(x)/substrate system was f ound to be much more reactive than was the TiN(x)/Al/substrate system. This may be explained either by the formation of an interfacial Al ni tride or oxide prior to the TiN(x) deposition, which blocks the reacti on in the case of the TiN(x) deposited on Al, or by point defects (vac ancies) which promote the reaction in the case when Al is deposited on TiN(x).