(AlCrTaTiZr)N/(AlCrTaTiZr)N0.7 bilayer structure of high resistance to the interdiffusion of Cu and Si at 900 °C

In this study, a multi-component (AlCrTaTiZr)N/(AlCrTaTiZr)N0.7 bilayer structure of about 15 nm thick was developed as a diffusion barrier material for Cu interconnects. The as-deposited (AlCrTaTiZr)N0.7 layer was characterized to be an amorphous structure, and the (AlCrTaTiZr)N layer was a nanocomposite structure. After annealing at a high temperature of 900 °C, the Si/(AlCrTaTiZr)N/(AlCrTaTiZr)N0.7/Cu film stack structure with the bilayer diffusion barrier remained stable. Only a slight amount of Cu penetrated into the top (AlCrTaTiZr)N0.7 layer. However, neither interdiffusion of Cu and Si through the (AlCrTaTiZr)N layer occurred, nor did any silicides form, indicating the excellent diffusion resistance of the bilayer structure.