To develop high signal speed semiconductor LSIs, Cu interconnection is one of the most important requirements. In the fabrication of Cu interconnections using CMP method, minimized dishing, erosion and reduction in micro-scratches are large issues to be realized. We performed a research for superior properties of Cu CMP. Finally, we succeeded in developing Abrasive Free (AF) Cu slurry suitable for these requirements.
We also developed slurry for barrier (TaN) with a high selectivity between TaN and SiO2 of 50 to reduce oxide (SiO2) loss. This reduced oxide loss is directly related to obtaining a controlled circuit resistivity.
By applying these two kinds of slurries, ULSIs with multilevel Cu interconnects and excellent reliabilities were obtained.