Evaluation of new amorphous hydrocarbon film for copper barrier dielectric film in low-k copper metallization

In recent ultra large-scale integration (ULSI), Cu wiring and low-k dielectrics are used to reduce resistive capacitive (RC) delay in interconnects. Cu diffusion barrier layers, such as SiC and SiCN, have relatively high k-values, thus they decrease effective k-values (k_eff) of dielectrics. For this issue, we propose a new amorphous hydrocarbon film (a-CH_x) as a Cu barrier dielectric deposited using a microwave-excited plasma reactor with a showerhead. Low ion bombardments and optimum deposition gases gave an excellent film, which achieved low leakage current and thermal resistance simultaneously. This film showed Cu diffusion barrier ability at 350°C and a lifetime of more than 10 years lifetime at 0.2MV/cm, which is sufficient for next-generation interlayer dielectric films.