Amorphous Ta–Si–N thin-film alloys as diffusion barrier in Al/Si metallizations

Amorphous Ta–Si–N thin films of a wide range of compositions were prepared by rf reactive sputtering of a Ta5Si3 target in a N2/Ar plasma. The relationship between films’ composition and resistivity is reported. All obtained films were tested as diffusion barriers between Al and Si. Backscattering spectrometry combined with cross-sectional transmission electron microscopy were used to determine the barrier effectiveness. It was found that aluminum can be melted on top of the Si/Ta–Si–N structure (675 °C for 30 min) without any evidence of metallurgical interactions between the layers.