CVD and ALD of Cobalt-tungsten alloy film as a novel Copper diffusion barrier

To reduce resistivity of interconnect, to enhance electromigration life time, and to improve a step coverage of barrier layer, cobalt and cobalt-tungsten alloy film was deposited by chemical vapor deposition (CVD) or atomic layer deposition (ALD) using octacarbonyl dicobalt (Co
₂
(CO)
₈
) and biscyclopentadienyl cobalt (Cp
₂
Co) as precursors, respectively. We demonstrated to form conformal cobalt films on to trench pattern and we confirmed that CVD/ALD cobalt-tungsten films have good barrier properties against copper diffusion.