Atomic layer deposition of Ru using a new zero-valent Ru precursor with a ligand system combining open and closed ligands

Abstract

With the miniaturization of semiconductor devices, the metals used as interconnect materials are affected by the significant “resistivity size effect.” The increase in resistivity owing to the resistivity size effect can directly degrade the performance of semiconductor devices. To solve this problem, the atomic layer deposition (ALD) of Ru has been actively studied to deposit high-quality Ru thin films that can maintain low resistivity even at thin thicknesses. Although ALD is an excellent method for depositing nanoscale thin films, the actual quality of the films deposited by ALD is greatly influenced by the properties of the precursor. We employed a newly developed zero-valent Ru precursor, stabilized by a combination of neutral open and closed ligands, to deposit high-quality Ru thin films using ALD. The Ru thin films deposited by the new Ru precursor exhibit improved growth characteristics compared to conventional high-oxidation-state Ru precursors and Ru precursors composed of closed ligands. In addition, Ru thin films could be deposited with outstanding conformality, even on trench substrates with a high aspect ratio. Consequently, high-quality Ru films for next-generation interconnect materials were successfully deposited by ALD using a new zero-valent Ru precursor containing an open ligand.