Reliability Evaluation of Semi-damascene Ru/Air-Gap Interconnect with Metal Pitch Down to 18 Nm

We evaluated the reliability of Semi-Damascene interconnects system fabricated by direct metal etch of Ru and Air-Gap as inter-metal dielectric. We show that intrinsically Ru does not drift into SiN and SiCO. Line-line TDDB results with Air-Gap widths of 8–16 nm (fixed line width of 10 nm) show a higher field acceleration factor compared to Dual-Damascene Ru/low-k systems and pass 10 years lifetime with V max > 0.75 V at 100°C for industry relevant line lengths. To address concerns related to moisture intake in Air-Gaps, we carried out humidity tests which showed no significant change in capacitance, leakage and VBD after 1000h at 85°C/85%RH. We also present that fully self-aligned vias pass electromigration and thermal storage tests.