| 초록 |
In semi-conductor industry, Cu metallization is an issue for several years. However Cu wiring require diffusion barrier layer to suppress Cu diffuse into dielectric layer like a low-k material. Self-forming barrier process is one of the barrier forming techniques. Many researchers using Mn-based Cu alloy material to get self-forming barrier. If so, it could be considered that existence of other material which replaced to Cu-Mn alloy material. In this work, the applicability of Cu-V alloy materials to the diffusion barrier layer was investigated and the utilization of external oxidation which is considered more effective barrier forming process was also studied. 3.9 at. % V (Vanadium) was selected as the alloy material to get self-forming barrier because its diffusivity in Cu and oxide formation energy are appropriate for diffusion barrier forming mechanism. Cu alloy film was deposited on low-k substrate using RF magnetron sputtering. At 300 °C and 500 °C, barrier forming process was carried out for 1 hr in Ar ambient or ultra-high vacuum to see the effect of external oxidation. External oxidation in Ar ambient which has a low oxygen concentration affects the behavior of V in Cu film. It was known that causes a change in resistivity of metal wiring. Moreover, through the additional annealing process at 350 °C, 450 °C and 550 °C for 12 hr, thermal stability were measured by I - V characteristic analysis. To evaluate resistivity of deposited Cu-V film layer, 4-point-probe method was used. Thickness, components and barrier stability of Self-forming barrier were measured by transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDAX), x-ray diffractometer (XRD) and I - V analysis respectively. At 300 °C for 1 hr, the formation of a barrier layer having a thickness about 3 nm was confirmed and the Cu was not found in the dielectric materials in Ar ambient. Furthermore resistivity reduction was observed during external oxidation treatment. It is comparable with that in ultra-high-vacuum. Also reliability test for thermal stress was proceeded and the result was stable below 450 °C. All these results indicate the formation of self-forming barrier layer which suppress the Cu diffuse into the dielectric materials and barrier properties are also suitable for diffusion barrier layer. Accordingly, Cu-V alloy is expected to be available to Cu metallization conditionally. |
