Selective Deposition and Ruthenium Superfill Exploration Beyond A10 Node Interconnects

We demonstrate that selective Ru CVD can enable multilayer semi-damascene (SD) interconnects -at the critical metal levels in A10 node and below. In ring oscillator simulations, it is shown that Ru SD flows can benefit from barrierless Ru vias. The Ru CVD has excellent selectivity towards low-k 3.0 in MP21 vias. When Ru vias are combined with Cu wires, the MP24 chain resistance is lower compared to barrierless dual damascene (DD) Ru. Furthermore, we applied Ru superfill CVD in a low-k DD test vehicle at MP21-MP26. The Ru superfill does not induce line bending in $\text{SiO}_{2}$ or in MP21 low-k lines due to its bottom-up growth nature. The Ru superfill resistance scaling down to $\sim 70 \text{nm}^{2}$ is confirmed with the physical area. The selective and superfill Ru CVD are enablers of multilayer SD Ru interconnects for future nodes.