Tantalum nitride, Ta-Si-N, and tantalum silicide films were investigated for use as a diffusion barrier in Al/Si metallization. The former two films were deposited by reactive sputtering of a Ta or TaSi2 target in Ar/N2 gas mixture. The TaSix films were fabricated by sputtering of TaSi2 target. Then, the Ta-Si-N and TaSix film were annealed at temperature 950°C for 15 seconds by RTA. The resistivities of Ta-Si-N, TaN, and TaSix films are about 180, 250, and 60 µohm-cm, respectively. The X-ray photoelectron spectroscopies were made to study the chemical structure of the films. For both nitrides, TaO comprises the native oxide formed at room temperature. A large amount of silicon nitride was formed on the surface of TaSix film during the RTA. Rutherford backscattering and Auger profile were performed to understand the degradation. It was found that these three films are effective diffusion barriers at temperature 620°C.