Ta-Si-N(10 nm)/Zr(20 nm) bilayer diffusion barrier was prepared between n-type silicon(100) wafer and Cu film by radio frequency reactive magnetron sputtering. The Cu/Ta-Si-N/Zr/Si samples were subsequently annealed at different temperatures ranging from 600 to 800 oC in high-purity N2 gas for 1 h. The thermal stability of the Cu/Ta-Si-N/Zr/Si system during annealing was investigated by X-ray diffraction(XRD), auger electron spectroscopy(AES), scanning electron microscopy(SEM) and four-point probe technique(FPP). The results show that Ta-Si-N deposited on Zr film is amorphous with low roughness. In addition, the diffusion of Zr atoms into Si substrate results in ZrSi2 formation which decreases effectively the contact resistance between the barrier and Si after annealing of Cu/Ta-Si-N/Zr/Si sample above 650 oC. Ta-Si-N/Zr bilayer can serve as effective diffusion barrier up to 750 oC