Three-Layer BEOL Process Integration with Supervia and Self-Aligned-Block Options for the 3 nm Node

The integration of a three-layer BEOL process which includes an intermediate 21 nm pitch level, relevant for the 3 nm technology node, is demonstrated. A full barrier-less Ruthenium (Ru) dual-damascene (DD) metallization allowed to test different dimensions of minimum island, via extension and tip-to-tip (T2T). Five-track place and route (PNR) and SRAM constructions were realized with the self-aligned block (SAB) technique. Stacked vias showed resistance modulation with the size of the minimum island due to the change in via chamfer. High aspect ratio supervias (SV), to bypass M2 and directly link M1 to M3, were tested with different metallization schemes. Line-to-line and T2T reliability tests passed the 10- year lifetime predictions. Finally, electromigration (EM) tests on SV showed no failures after 140 hours of accelerated stress conditions.