Synthesis of Novel Ru Precursors for Atomic Layer Depostion

Abstract

Ruthenium (Ru), which has a low bulk resistivity and a high work function, is a well-known metal for electrode materials in various microelectronic applications, such as Dynamic Random Access Memories (DRAM), Ferroelectric Random Access Memories (FRAM), and metal-oxide-semiconductor field-effect transistors (MOSFET). Also, Ru thin films can be used as diffusion barrier layers to improve the electromigration resistance in interconnect systems due to the excellent adhesion characteristics between Ru and Cu. Therefore, research on Ru thin films, that can be deposited by methods such as MOCVD (Metal-Organic Chemical Vapor Deposition) and ALD (Atomic Layer Deposition), is attracting many researchers. To apply these deposition techniques, Ru precursors with volatility and thermal stability are required. In this study, for the synthesis of Ru precursors that can satisfy all conditions, new Ru precursors were designed and prepared by using Ru(η5-Tropone)(η5-CHT) (CHT = Cycloheptatriene) as a starting material, to yield five new ruthenium precursors: Ru(II)(C7H9)(C8H11O) (1), Ru(II)(C7H9)(C9H14O) (2), Ru(II)(C7H9)(C13H14O)(3), Ru(II)(C7H9)(C8H9O) (4), and Ru(II)(C7H9)(C9H11O) (5). These compounds were characterized by 1H-Nuclear Magnetic Resonance (NMR), Mass Spectrometry (MS), Fourier-transform Infrared Spectroscopy (FT-IR), Elemental Analysis (EA), Thermal Gravimetric Analysis (TGA), and single crystal X-ray diffraction.