The atomic layer deposition (ALD) of Ru using a metal–organic precursor, tricarbonyl­(trimethylenemethane)ruthenium [Ru­(TMM)­(CO)3] and O2 as a reactant is reported. The high vapor pressure, thermal stability, and relatively small ligands of the precursor facilitate efficient ALD. Typical self-limiting growth and an ALD temperature window of 220–260 °C are observed along with significantly high growth per cycle (GPC) (∼1.7 Å) and short incubation cycles (∼6) at 220 °C. Density functional theory calculations indicate that the high growth rate and self-limiting behavior can be attributed to the characteristics of the trimethylenemethane ligand. The as-grown polycrystalline films (average grain size ∼20 nm and negligible impurities) were evident from plan-view transmission electron microscopy. The variation in film resistivity with increasing film thickness and deposition temperature was investigated with and without annealing. Films deposited at 260 °C show low resistivity (∼12.9 μΩ cm), which further decreases (∼9.8 μΩ cm) postannealing at 500 °C. A thin Ru film is successfully deposited with 100% step-coverage on a dual-trench structure having an aspect ratio of ∼6.3 (minimum width: ∼15 nm). The interfacial adhesion energy measured using the four-point bending test exceeds 7 J m–2, regardless of the dielectric material and annealing treatment. The Ru precursor permits enhanced nucleation and GPC at relatively low deposition temperatures to construct high-quality Ru films with significantly low resistivity using simple, plasma-free techniques, and is suitable for the fabrication of emerging Ru films to replace Cu-based interconnects.

Atomic layer deposition (ALD) is a suitable technology for conformally depositing thin films on nanometer‐scale 3D structures. RuO2 is a promising diffusion barrier for Ru interconnects owing to its compatibility with Ru ALD and its remarkable diffusion barrier properties. Herein, a RuO2 diffusion barrier using an ALD process is developed. The highly reactive Ru precursor [tricarbonyl(trimethylenemethane)ruthenium] and improved O2 supply enable RuO2 deposition. The optimal process conditions [pulsing time ratio (tO2/tRu): 10, process pressure: 1 Torr, temperature: 180 °C] are established for the RuO2 growth. Growth parameters, such as the growth rate (0.56 Å cycle–1), nucleation delay (incubation period: 6 cycles), and conformality (step coverage: 100%), are also confirmed on the SiO2 substrate. The structural and electrical properties of the Ru/RuO2/Si multilayer are investigated to explore the diffusion barrier performance of the ALD‐RuO2 film. The formation of Ru silicide does not occur without the conductivity degradation of the Ru/RuO2/Si multilayer with an increase in the annealing temperature up to 850 °C, thus demonstrating that interdiffusion of Ru and Si is completely suppressed by a thin (5 nm) ALD‐RuO2 film. Consequently, the practical growth behavior and diffusion barrier performance of RuO2 can serve as a potential diffusion barrier for Ru interconnects.

No abstract

This study suggests a Ru/ZnO bilayer grown using area‐selective atomic layer deposition (AS‐ALD) as a multifunctional layer for advanced Cu metallization. As a diffusion barrier and glue layer, ZnO is selectively grown on SiO2, excluding Cu, where Ru, as a liner and seed layer, is grown on both surfaces. Dodecanethiol (DDT) is used as an inhibitor for the AS‐ALD of ZnO using diethylzinc and H2O at 120 °C. H2 plasma treatment removes the DDT adsorbed on Cu, forming inhibitor‐free surfaces. The ALD‐Ru film is then successfully deposited at 220 °C using tricarbonyl(trimethylenemethane)ruthenium and O2. The Cu/bilayer/Si structural and electrical properties are investigated to determine the diffusion barrier performance of the bilayer film. Copper silicide is not formed without the conductivity degradation of the Cu/bilayer/Si structure, even after annealing at 700 °C. The effect of ZnO on the Ru/SiO2 structure interfacial adhesion energy is investigated using a double‐cantilever‐beam test and is found to increase with ZnO between Ru and SiO2. Consequently, the Ru/ZnO bilayer can be a multifunctional layer for advanced Cu interconnects. Additionally, the formation of a bottomless barrier by eliminating ZnO on the via bottom, or Cu, is expected to decrease the via resistance for the ever‐shrinking Cu lines.

No abstract