Improvement of Diffusion Barrier Performance of Ru Thin Film by Incorporating a WHfN Underlayer for Cu Metallization

The performances of a novel Ru/WHfN barrier against Cu diffusion are compared with those of Ru and Ru/WN barriers by sheet resistance, X-ray diffraction, elemental depth profiles, and leakage–current measurement of metal-oxide-silicon capacitors. For the Cu/barrier/Si samples, both and barriers fail after annealing at 500 and , respectively. However, the barrier can still maintain the perfect ability to prevent Cu penetration at the failure temperature of the barrier. This could be attributed to the fact that the incorporation of Hf into WN greatly enhances the crystallization temperature of WHfN, whose amorphous texture can be maintained after annealing. In contrast, the WN film begins to crystallize after annealing, and many of the generated grain boundaries facilitate Cu diffusion through the barrier.