Large Grain Ruthenium for Alternative Interconnects

Abstract

We demonstrate Ru wires with more than 4.6× larger grain sizes, with over 30% reduction in resistivity at highly scaled wire areas down to 68 nm2, compared to conventional damascene Ru wires. A method of transferring the extraordinarily large grain structures from thick Ru films to wires is presented. Suppressed grain-boundary scattering in the Ru wires is attributed to the low resistivity, which is analyzed using semi-classical resistivity model. The results strongly support Ru as a candidate alternative interconnect material to replace Cu.