Full reliability study of advanced metallization options for 30 nm 1/2pitch interconnects

摘要

Different metallization options that allow filling 30 nm 1/2pitch interconnect trenches have been explored and their full reliability performance has been benchmarked to conventional PVD TaNTa/PVD Cu seed based metallizations. CVD Co as seed enhancement layer shows no deterioration in barrier performance and improved electromigration performance, but the activation energy for electromigration was 0.68 ± 0.20 eV, which is at the lower end of the expected value of 0.85-0.95 eV for this parameter. When integrating our trenches in a k = 3.2 non-porous SiCOH low-fc material, PVD RuTa barriers with 90%Ru and 10%Ta show degraded barrier performance and significant lowering of activation energy for electromigration (0.59 ± 0.05 eV) while when using SiO_2 as intermetal dielectric, no significant reliability deterioration is observed. Finally, it is shown that, using an optimized PVD Cu seed, standard PVD TaNTa-barriers give excellent barrier performance and that typical electromigration lifetime specs can be met with this metallization scheme down to 30 nm 1/2pitch.