Copper damascene interconnection with tungsten silicon nitride diffusion barrier formed by electron cyclotron resonance plasma nitridation

This paper describes the application of tungsten silicon nitride (WSiN) formed by electron cyclotron nitridation (ECR) plasma nitridation as a diffusion barrier for copper (Cu) damascene interconnection. WSiN(6 nm)/WSix(14 nm) multi-layer prevents Cu diffusion well when WSiN is formed with RF bias application to the substrate. The RF power increases the nitrogen concentration of the WSiN and enhances its amorphousness, which lead to the improved barrier capability. WSiN can be formed inside the trench, and the WSiN on the trench side walls prevents Cu diffusion. The use of this extremely thin barrier metal suppresses the increase of interconnection resistivity.