Suppress copper diffusion through barrier metal-free structure by using ion implantation into low-k material

Currently, Cu and spin on organic polymers (SOP) are leading candidates for ULSI interconnect technology. Devices integrated with low-k materials and Cu films are capable of improved performance. Methyl silsesquioxane (MSQ), a spin-on material with low dielectric constant, can successfully suppress Cu diffusion without using barrier metal through implantation of nitrogen into the low dielectric constant material. A MOS capacitor structure, studied in this work, shows better barrier capability and lower leakage current after co-implanting nitrogen and fluorine into the low dielectric material. In our work, we successfully control the MSQ film's dielectric constant and its leakage current by ion implantation, providing a good way to integrate low dielectric constant materials and copper in the same devices. Not only we do not need to deposit an extra barrier layer to prevent Cu penetration, but the dielectric constant is also reduced at the same time. More detailed experiments and electrical measurements are continuing.