Synthesis and characterization of ruthenium complexes with two fluorinated amino alkoxide chelates. The quest to design suitable MOCVD source reagents

The synthesis and characterization of ruthenium complexes [Ru(CO)₂(amak)₂] and [Ru- (COD)(amak)₂] (where COD = 1,4-cyclooctadiene) are reported, where (amak)H is an abbreviation for a series of fluorinated amino alcohol ligands with formula HOC(CF₃)₂CH₂-NHR, where R = H, Me, Et, and (CH₂)₂OMe. The carbonyl complex [Ru(CO)₂(amak1)₂] (1 with R = H) was examined by X-ray diffraction (XRD), showing an octahedral coordination for the Ru atom, with two cis carbonyl ligands and two amino alkoxide chelates. For the COD complexes [Ru(COD)(amak1)₂] (3 with R = H) and [Ru(COD)(amak3)₂] (4 with R = Et), the structural analysis indicated the existence of two distinct spatial arrangements of amino alkoxide chelates with respect to the coordinated COD ligand, depending on the type of amino group selected. All of these complexes show good volatility and thermal stability. For complexes 2 and 4, which are more volatile and low-melting, chemical vapor deposition (CVD) experiments were conducted at temperatures of 325-425 °C, using both H₂ and a mixture of 2% O₂ in argon as the carrier gas. Scanning electron micrographs (SEMs) were taken to reveal the surface morphologies; these Ru thin films were found to contain low levels of carbon and oxygen impurities, as measured by X-ray photoelectron spectroscopy (XPS).