Synthesis and Characterization of Tris(β‐ketoiminato)ruthenium(III) Complexes: Potential Precursors for CVD of Ru and RuO₂ Thin Films

Abstract

The synthesis and characterization of Ru III metal complexes [Ru(keim1) 3 ] (1) and [Ru(keim2) 3 ] (2) are reported, where (keim)H is an abbreviation for the fluorinated ketoimine ligands with formula HOC(CF 3 )=CHCR=NMe; (keim1)H with R = Me and (keim2)H with R = CF 3 . These newly synthesized complexes were characterized by spectroscopic methods, while the second complex, 2, was further examined by single-crystal X-ray diffraction (XRD), revealing an octahedral coordination for the Ru cation, with three ketoiminate arranged in a mer-configuration, a consequence of the enhanced steric interaction between ligands. Moreover, both Ru metal complexes show good volatility and thermal stability. CVD experiments were conducted using these complexes at temperatures of 325±450 C. The Ru metal and RuO 2 thin films on silicon wafers were successfully obtained using either a mixture of 2 % O 2 in argon or pure O 2 as the carrier gas, respectively. Our result shows that a 2 % O 2 concentration induces the formation of Ru metal, while that only complex 1 gives formation of a columnar RuO 2 phase upon switching to pure O 2 as the CVD carrier gas. Scanning electron microscopy (SEM) images were taken to reveal surface morphologies, while X-ray photoelectron spectroscopy (XPS) and XRD were utilized to access their atomic composition as well as the intrinsic packing of the as-deposited thin film materials.

Nanostructured Fe2O3 Processing via Water‐Assisted ALD and Low‐Temperature CVD from a Versatile Iron Ketoiminate Precursor

“…The resulting metal complexes could be promising candidates which potentially fulfill the criteria of volatility, suitable reactivity and sufficient thermal stability ( Scheme ) for atomic layer deposition and sufficient temperature window between volatilization and decomposition for low‐temperature CVD applications. Metal ketoiminates have been considered and applied as precursors for the CVD of metal oxides and nitrides of various transition metals, e.g., Ru, Ta, Nb, Zn, Pd, Cu, Ni, Ir, Ti . So far, none of these compounds have been tested for ALD applications, to the best of our knowledge.…”

Tris(β-ketoiminato)ruthenium(III) complexes: Electrochemical and computational chemistry study

“…The synthesis of ligand 3 described below. The five ruthenium complexes of the corresponding ligands were synthesized by using literature methods of related complexes as a guide [19,12].…”

“…x / RuCl3 . 3H2O) with the corresponding ketoimine ligands [12], or by stirring a mixture of RuCl3 . 3H2O and the relevant ketoimine ligand at room temperature [19].…”

Ruthenium complexes as precursors for chemical vapor-deposition (CVD)

“…This can also account for the greater stability of the source precursor. 78 Under inert gas ow the mass loss of the precursor out of a crucible with time is nearly linear (for the exact theory, see ref. 81) and the residual mass should be negligible.…”

“…Chou et al 78 synthesized two octahedral Ru(III) complexes such as [Ru(keim1) 3 ] 49 and [Ru(keim2) 3 ] 50, (keim1 ¼ -OC(CF 3 ) ¼ CHC-CH 3 ¼ NMe, keim2 ¼ -OC(CF 3 ) ¼ CHC-CF 3 ¼ NMe) with good volatility and thermal stability. The CVD study showed that the lm structures varied according to the nature of source reagent and carrier gas.…”