Interface Barrier Technologies in Advanced Semiconductor Interconnect Metals and Their Reliability Impact: The Evolution from Cu to Co/Ru
DOI:
https://doi.org/10.54097/tqk6gf59Keywords:
advanced interconnects, diffusion barriers, cobalt interconnects, ruthenium interconnects, electromigration, TDDB, semi-damascene.Abstract
In the sub-10 nm regime of interconnect, as the dimensions between the backends are becoming smaller, a coupled electrical, reliability, and manufacturability crisis is experienced with the traditional Cu/low-k dual-damascene platform, which is based on a Ta/TaN barrier, a liner stack and a Cu conductor. It is not only the resistivity size effect of Cu alone that functions as a bottleneck, but also the harsh loss of effective conducting cross-section to high-resistivity barrier/liner layers, the reinforcement of interface scattering, and the attendant increase in risks of electromigration, time-dependent dielectric breakdown and thermomechanical failure. This paper reviews the evolution of interface barrier technologies in advanced interconnects, examines the scaling limits of the conventional Cu/Ta (TaN) scheme, and analyzes representative routes including Co-W, Ru-Ta, atomically thin 2D materials, graphene encapsulation, Co-Ti single barrier/liner layers, Ru-Zn self-forming barriers, and Ru semi-damascene integration. The central argument is that the competition in advanced interconnects has shifted from simply identifying the metal with the lowest bulk resistivity to co-designing low-size-effect metals, ultrathin functional interfaces, and new integration architectures to minimize effective line resistance while maximizing reliability. Interface barriers are therefore no longer passive diffusion blockers; they are the functional layers that will decide whether post-Cu interconnect technologies can be industrialized.
Downloads
References
[1] D. Gall, “The search for the most conductive metal for narrow interconnect lines,” Journal of Applied Physics, vol. 127, no. 5, Art. no. 050901, 2020, doi: 10.1063/1.5133671.
[2] D. Gall, J. J. Cha, Z. Chen, H.-J. Han, C. Hinkle, J. A. Robinson, R. Sundararaman, and R. Torsi, “Materials for interconnects,” MRS Bulletin, vol. 46, pp. 959–966, 2021, doi: 10.1557/s43577-021-00192-3.
[3] Z. Li, Y. Tian, C. Teng, and H. Cao, “Recent Advances in Barrier Layer of Cu Interconnects,” Materials, vol. 13, no. 21, Art. no. 5049, 2020, doi: 10.3390/ma13215049.
[4] B. M. C. Oliveira, R. F. Santos, A. P. Piedade, P. J. Ferreira, and M. F. Vieira, “Co-W Barrier Layers for Metallization of Copper Interconnects: Thermal Performance Analysis,” Nanomaterials, vol. 12, no. 10, Art. no. 1752, 2022, doi: 10.3390/nano12101752.
[5] N. Torazawa, T. Hinomura, S. Hirao, E. Kobori, H. Korogi, and S. Matsumoto, “Effects of N Doping in Ru-Ta on Barrier Property and Reliability Performance for Cu Interconnects,” ECS Journal of Solid State Science and Technology, vol. 5, no. 7, pp. P433–P437, 2016, doi: 10.1149/2.0271607jss.
[6] C.-L. Lo, M. Catalano, K. K. H. Smithe, L. Wang, S. Zhang, E. Pop, M. J. Kim, and Z. Chen, “Studies of two-dimensional h-BN and MoS2 for potential diffusion barrier application in copper interconnect technology,” npj 2D Materials and Applications, vol. 1, Art. no. 42, 2017, doi: 10.1038/s41699-017-0044-0.
[7] C.-Y. Kuo, J.-H. Zhu, Y.-P. Chiu, I.-C. Ni, M.-H. Chen, Y.-R. Wu, and C.-I. Wu, “Graphene-All-Around Cobalt Interconnect with a Back-End-of-Line Compatible Process,” Nano Letters, vol. 24, no. 6, pp. 2102–2109, 2024, doi: 10.1021/acs.nanolett.3c04833.
[8] X. Zhou, J. Xu, J. Gao, J. Liu, D. Zhang, Y. Liu, X. Sun, M. Kong, Y. Li, J. Li, W. Wang, T. Ye, and J. Luo, “Time-dependent dielectric breakdown (TDDB) for Co0.65Ti0.35 as a single barrier/liner in local Co interconnects,” Journal of Materials Science: Materials in Electronics, vol. 33, pp. 14063–14070, 2022, doi: 10.1007/s10854-022-08337-z.
[9] A. Joi, A. Leśniewska, D. Dictus, K. C. Tso, K. Venkatraman, Y. Dordi, K. Croes, Z. Tőkei, S. K. Yadav, and P.-W. Wu, “Doped Ru to enable next generation barrier-less interconnect,” Journal of Applied Physics, vol. 132, no. 17, Art. no. 175704, 2022, doi: 10.1063/5.0108688.
[10] B. Wehring, F. Karakus, L. Gerlich, B. Lilienthal-Uhlig, M. Hecker, and C. Leyens, “Material screening for future diffusion barriers in Cu interconnects: Modeling of binary and ternary metal alloys and detailed analysis of their barrier performance,” Journal of Applied Physics, vol. 135, no. 21, Art. no. 215302, 2024, doi: 10.1063/5.0211802.
[11] X. Zhang et al., “Ruthenium interconnect resistivity and reliability at 48 nm pitch,” in 2016 IEEE International Interconnect Technology Conference/Advanced Metallization Conference (IITC/AMC), 2016, pp. 31–33, doi: 10.1109/IITC-AMC.2016.7507650.
[12] A. Gupta et al., “Two-metal-level semi-damascene interconnect at metal pitch 18 nm and aspect-ratio 6 routed using fully self-aligned via,” in 2023 IEEE International Electron Devices Meeting (IEDM), 2023, pp. 1–4, doi: 10.1109/IEDM45741.2023.10413784.
[13] S. Decoster et al., “Patterning challenges for direct metal etch of ruthenium and molybdenum at 32 nm metal pitch and below,” Journal of Vacuum Science & Technology B, vol. 40, no. 3, Art. no. 032802, 2022, doi: 10.1116/6.0001791.
[14] H.-Y. Wu, Y.-Y. Fang, Y.-L. Chen, J.-F. Lu, M.-Y. Lu, S.-Y. Chang, and P. Y. Keng, “Molecularly tailored SAMs for Ru interconnects: high-temperature stability, suppressed metal diffusion, and enhanced adhesion,” NPG Asia Materials, vol. 17, Art. no. 45, 2025, doi: 10.1038/s41427-025-00627-2.
[15] H. Kim, S. Oh, S. An, J. Kim, T. Kim, S. Jeong, O. Kaya, T. Galvani, S. Roche, J. J. Cha, M. Chhowalla, H. S. Shin, and H.-J. Shin, “Future interconnect materials for highly integrated semiconductor devices,” Nature Reviews Electrical Engineering, vol. 2, no. 12, pp. 835–845, 2025, doi: 10.1038/s44287-025-00233-y.
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Highlights in Science, Engineering and Technology
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
