The work aims to improve the failure temperature of the copper interconnect diffusion barrier. Cu/AlCrTaTiZrNx/Si high-entropy alloy thin film system was deposited by reactive magnetron sputtering under different nitrogen flow rates and then vacuum-annealed at 600, 700, 800, 900 ℃. The microstructure, 3D morphology, etc. of the thin film were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The high-entropy alloy film was amorphous in the condition without nitrogen. As the flow rate of nitrogen increased, the crystallinity of the film became better and the film structure was FCC structure. With the increase of nitrogen flow rate, the surface roughness of this film decreased. The high-entropy alloy nitride film had the best compactness at a nitrogen flow rate of 20%. The diffusion barrier structure of the Cu/AlCrTaTiZrN20/Si thin film system was mainly amorphous-coated nanocrystalline structure. After annealing at 800 ℃, there was no Cu-Si compound in the thin film and the sheet resistance was 0.0937 Ω/□. After annealing at 900 ℃, a large number of large-grained high-resistivity Cu-Si compounds in irregular pentagon emerged at Si substrate of Cu/AlCrTaTiZrNx/Si high-entropy alloy thin film system. As the nitrogen flow rates increases, the diffusion barrier property of the AlCrTaTiZrNx high-entropy alloy nitride film first increases and then decreases. The diffusion barrier property of the high-entropy alloy nitride film is optimal at a nitrogen flow rate of 20%, and can still act as a barrier after annealing at 800 ℃.