Small and Simple Molecular Structure Based Thermally Stable Ruthenium Precursor in Advancing Ruthenium ALD Process for Scaled Interconnect Metallization

Abstract

Ruthenium (Ru) via atomic layer deposition (ALD) has emerged as a promising alternative to copper-interconnects. For the first time, a small yet simple molecular structure Ru precursor, [Ru(trimethylenemethane (TMM))(p-cymene)], with excellent thermal stability up to 400°C is introduced that enables a high-temperature ALD-Ru process with a high growth per cycle of ≈1.28Å cycle−1 and a short incubation period (≈8 cycles) on TiN, facilitating uniform, dense film growth. The process achieves low impurity levels and resistivities as low as 10.6µΩ cm at 350°C without postannealing, approaching bulk Ru values (7.4µΩ cm). Additionally, no Ru nucleation is observed on SiO<inf>2</inf> even after 1000 cycles, indicating excellent substrate selectivity. Computational analyses confirm the substrate-selective adsorption behavior of the precursor, favoring TMM-terminated configurations on Ru and RuO<inf>2</inf>, while nucleation on SiO<inf>2</inf> can be delayed. Fragmentation energy calculations further support the precursor's thermal robustness through strong Ru─ligand bonding. Advanced crystallography/microstructure analysis using electron backscatter diffraction reveals that the enhanced grain growth and the formation of low-energy coincidence site lattice boundaries are critical for minimizing resistivity, which is supported by combined Fuchs–Sondheimer–Mayadas–Shatzkes modeling. These findings position the new Ru precursor as a robust candidate for durable, scalable ALD-Ru processes in advanced interconnect technology. © 2025 The Author(s). Advanced Science published by Wiley-VCH GmbH.