CVD of cobalt–tungsten alloy film as a novel copper diffusion barrier

To reduce the resistivity of interconnects, to enhance electro-migration lifetime, and to improve the step coverage of the barrier layer, we deposited cobalt and cobalt–tungsten alloy films by chemical vapor deposition (CVD) using octacarbonyl dicobalt [Co2(CO)8] and hexacarbonyl tungsten [W(CO)6] as precursors, respectively. We demonstrated the formation of a conformal cobalt film on a trench pattern and confirmed that CVD cobalt–tungsten films have good barrier properties against copper diffusion.