Layer Transfer of Epitaxial Ru by Metal-Metal Bonding: Towards Single-Crystal Interconnects
Year: 2026
Type: conference-paper
Abstract: Continued scaling of interconnect dimensions into the sub-10 nm regime challenges conventional Cu dual-damascene metallization due to rising resistivity, reliability degradation, and integration complexity. Ru is a promising alternative; however, polycrystalline Ru remains limited by grain-boundary scattering and patterning constraints at advanced nodes. Here, we present a metal layer-transfer integration scheme that enables single-crystal Ru interconnects by decoupling epitaxial metal growth from BEOL patterning. High-quality epitaxial Ru films are sputter-deposited on AlN (0001)/Si (111) at BEOL-compatible temperatures and transferred to device wafers via Ru–Ru wafer-to-wafer bonding. Structural characterization confirms excellent crystalline quality and coherent epitaxial alignment, while electrical measurements demonstrate near-bulk resistivity with weak thickness dependence. Vacuum bonding with surface activation followed by post-bond annealing yields void-free Ru–Ru interfaces and induces solid-phase epitaxial regrowth across the bonding interface. These results indicate that metal-to-metal bonding-based layer transfer can become a viable pathway for integrating single-crystal interconnects in future technology nodes.
Institutions: IMEC, EV Group (Austria)
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7165035348