Self-forming barrier layer from CuMnTi alloy layer on SiO2 substrate

•The self-forming barrier (SFB) layer was fabricated from CuMnTi alloy layer.•The SFB layer has a thickness of 5 nm.•The SFB layer improves the adhesion of Cu interconnect layer.•The SFB layer effectively prevents element diffusion of Cu element into SiO2 substrate.

Advancement of large-scale integrated interconnect structure requires an ultra-thin and uniform diffusion barrier layer between Cu interconnect and insulating layers. As a promising alternative barrier to the conventional Ta/TaN, the self-forming barrier layer from the CuMnTi alloy layer was investigated in this work. In order to achieve the self-forming barrier layer, the CuMnTi alloy layer first was deposited on SiO2 substrate by magnetron sputtering. Second, the alloying elements were driven and migrated to the interface, and moreover, reacted with SiO2 to form the self-forming barrier layer. The self-forming barrier layer has a thickness of about 5 nm. The annealing leads to an obvious decrease of resistivity from 50.10 μΩ cm to 4.23 μΩ cm for the CuMnTi alloy layer. The self-forming barrier can improve the adhesion of Cu interconnect layer and effectively prevent element diffusion between Cu interconnect and insulating SiO2 substrate.