A novel integration scheme for self-aligend Ru topvia as post-Cu alternative metal interconnects

A novel integration process for self-aligned topvia Ru interconnects has been demonstrated, where lines are patterned through a subtractive scheme and vias are formed through a damascene scheme. TiN spacer has been utilized for improved etch selectivity to ensure self-aligned via patterning. Topvia structure should have a great advantage in increasing the percentage of lines with airgap and simulation results support that a significant reduction in capacitance can be achieved by incorporating airgaps in Ru topvia interconnects.