Two-metal-level semi-damascene interconnect at metal pitch 18 nm and aspect-ratio 6 routed using fully self-aligned via

Abstract

High-aspect ratio (HAR-6-8) bottom Ru metal lines (M2), at CDs 7-10 nm and metal pitch (MP) 18-26 nm, in a two-metal level Ru semi-damascene interconnect configuration with fully self-aligned via (FSAV) is reported for the first time. M2 is patterned using EUV-SADP and subsequent direct-metal-etch (DME) of Ru film. At critical dimension (CD) of 10 nm, the resistance (R) of Ru line at AR6, measures at 235 Ω/μm which is 75% lower than the simulated Cu line R at AR2. The R yield of Ru lines across 300 mm wafer is >90% for MP20-26 nm. The FSAV R is competitive; vias landing on AR6 lines show a median R~33Ω with bottom CD of 8.5x12.3 nm2. Good quality of HAR Ru line interfaces is indicated by thermal shock tests showing no change in line R post 1000 h of thermal cycling between -50°C to 125°C.