Plasma-deposited dielectrics for Cu metallization systems

The interaction of copper with PECVD silicon oxynitride films was investigated by different analytical and electrical methods. Using AES-depth profiling and RBS measurements, no copper diffusion in films investigated 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-structures with copper dots. The shift of the C-V curves resulting from copper migration decreases with an increasing N/O-ratio of SiOxNy films, demonstrating the better barrier properties of silicon nitride compared to silicon oxide. Additionally, the time to failure (TTF) was studied as a function of thermal and electrical stresses. Again, SiNx-samples achieved the highest TTF-values. The polarity dependence of the leakage current suggests a Cu ion drift transport mechanism. (C) 1998 Elsevier Science S.A.