Multi-component AlCrTaTiZrMo-nitride film with high diffusion resistance in copper metallization

Highlights: • The Cu(100 nm)/AlCrTaTiZrMoN_0.2(10 nm)/Si structure were annealed from 700 °C to 900 °C for 1 h in high vacuum. • The as-deposited AlCrTaTiZrMoN_0.2 film was composed of face center cubic structure nanocrystalline surrounded by amorphous matrix. • The film began crystallization with the formation of grain boundaries, and some micro-crack and void. • Production of many obvious Cu₃Si and Cr₅Si₃ phase indicated that the Cu atoms diffused and reacted with Si substrate along the grain boundaries, micro-crack and void. In this study, a multi-component AlCrTaTiZrMo-nitride film with a total thickness of about 10 nm have been investigated as a diffusion barrier layer for copper metallization. To achieve the diffusion barrier characteristic between Cu and Si, the Cu/AlCrTaTiZrMo-nitride/Si structure were annealed at temperatures from 700 °C to 900 °C for 1 h in high vacuum. Under annealing at high temperature of 800 °C, the layer still remained amorphous with nanocrystalline features, effectively retarded the interdiffusion between Cu and Si without the formation of any Cu-silicides. After annealing at 900 °C, Cu-silicides compound formed with the appearance of island-like surface, revealing that the interdiffusion occurred between Cu and Si. The findings indicate that HEA-nitride layer have excellent diffusion barrier performance before annealing at 900 °C. Its high diffusion barrier performance and thermal stability are probably attributable to the amorphous structure with nano-crystalline features, the simple solid solution structure, the multiple-element effects, and the high stacking density without rapid diffusion path.