Samsung Advanced Institute of Technology

In the forefront of future semiconductor technology lies the criticality of precise material control and layering, where variations in properties play a pivotal role. In this endeavor, area-selective atomic layer deposition (ASD) methods emerge as indispensable tools for crafting semiconductor components and structures tailored to specific characteristics and requirements. Ruthenium (Ru) is attracting significant interest as a low-resistivity conducting material poised for next-generation interconnect technology. However, oxidants such as O₂, O₃, and H₂O have been identified as counter reactants for depositing metallic Ru films. Consequently, the notable rise in contact resistance due to substrate oxidation by these oxidant counter reactants has posed a significant drawback in both ALD and ASD Ru processes. In this study, Ru ASD is studied using a two-step ALD process with sequential use of H₂ and O₂ as counter reactants and an aminosilane precursor inhibitor (PI), dimethylaminotrimethylsilane (DMATMS). Both theoretically and experimentally, it has been demonstrated that in the 2-step Ru ALD process, the oxide layer can be significantly eliminated through the reduction reaction mechanism involving the H₂ counter reactant and the oxidized metal surface. This principle allows for the simultaneous adsorption of Ru precursor, tricarbonyl-(trimethylenemethane)-ruthenium (TRuST) while removing the oxide layer from the oxidized metal surface. As a result, it suppresses Ru growth on the DMATMS-inhibited SiO₂ surface in the ASD process, enabling deposition exclusively on the metal (Mo) surface. The proposed Ru ASD for anti-oxidation using the two-step ALD process could hold significant promise for driving advancements in interconnect technology for commercial applications.