PECVD OF SILICON OXYNITRIDE FOR COPPER METALLIZATION SYSTEMS

The interaction of copper with PECVD silicon oxynitride films were inv estigated by different analytical and electrical methods. Using AES-de pth profiling and RES measurements, no copper diffusion in films inves tigated was observed after applying a thermal stress of 450 degrees C for 1 h. However, copper migration was detected after applying thermal and electrical stress simultaneously (BTS). C-V and I-V measurements before and after different BTS-conditions were performed on MIS-struct ures. Additionally, the time to breakdown was studied as a function of thermal and electrical stresses. From the resulting arrhenius plots t he activation energies for the lowest electric fields applied were det ermined to be 1.85 eV for SiN and 1.3 eV for SiO. The polarity depende nce of leakage current for both materials studied suggests a Cu ion dr ift transport mechanism. From all materials investigated, silicon nitr ide showed the best barrier behaviour against copper interaction.