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

초록

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 degrees C is introduced that enables a high-temperature ALD-Ru process with a high growth per cycle of approximate to 1.28 & Aring; cycle-1 and a short incubation period (approximate to 8 cycles) on TiN, facilitating uniform, dense film growth. The process achieves low impurity levels and resistivities as low as 10.6 mu Omega cm at 350 degrees C without postannealing, approaching bulk Ru values (7.4 mu Omega cm). Additionally, no Ru nucleation is observed on SiO2 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 RuO2, while nucleation on SiO2 can be delayed. Fragmentation energy calculations further support the precursor's thermal robustness through strong Ru & horbar;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.

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