Fabrication of the Electroless NiMoB Films as a Diffusion Barrier Layer on the Low-k Substrate

Fabrication of electroless NiMoB thin films as a diffusion barrier layer and capping layer for Cu interconnects in ULSI with low-k inter level dielectrics were developed. The films containing the Mo were expected to improve the barrier property for Cu diffusion and thermal stability of the films. This study included the novel wet formation process, i.e. we use self-assembled monolayer and catalyzing process to obtain the uniform catalyzed surface to initiate the electroless deposition reaction. The deposition rate was strongly dependent on the MoO3 concentration in the solution. The content of Mo in the deposit increased as the concentration of MoO3 in the solution increased. Thermal stability of the NiMoB film for Cu diffusion was evaluated. The obtained films (Mo concentration = 20 to 25at %) was stable against vacuum annealing under 400{degree sign}C