Two-metal-level semi-damascene interconnect with variable width bottom metal at metal pitch 18-26 nm and aspect ratio 4-6 routed using fully self-aligned via

This work reports variable metal width Ru semi-damascene bottom metal line integration at metal pitch (MP)=18-26 nm, for the first time at high-aspect ratios of 4 and 6. It is also the first report on routing of such lines to a top semi-damascene metal level using a fully self-aligned via (FSAV). Average core-gap line resistance (R) at MP=18 nm is ~240 Ω/µm at AR6. Line-line leakage yields of 50% and 30% at AR4 and AR6, respectively, is achieved at MP=18 nm which exceed 90% and 70% at MP=20 nm. MP=18 nm, AR4 line-line TDDB at 100 ºC show an extrapolated failure time of >10y. Ru FSAV fabricated on AR4, MP=18 nm Ru line has a kelvin resistance of ~20 Ω at via bottom CD ~9.4 nm and via height ~8.4 nm. Electromigration (EM) on single vias show robust Ru-Ru interface with no failures post 135h of EM stress at ~10 MA/cm² and 330 ºC.