Fluorinated aminoalkoxide CuII complexes: new CVD precursors for deposition of copper metal

Abstract

Volatile low-melting Cu^II metal complexes of formula Cu[OC(CF₃)R¹CH₂NHR²]₂ (R¹ = CF₃ or CH₃; R² = CH₂CH₂OMe, Buⁱ, or Bu^t) and Cu[OC(CF₃)R¹CH₂NMe₂]₂ (R¹ = CF₃ or CH₃) have been synthesized and characterized by spectroscopic methods. A single-crystal X-ray diffraction study on Cu[OC(CF₃)₂CH₂NHCH₂CH₂OMe]₂ shows that one methoxyethyl group of the aminoalkoxide ligand forms an intramolecular dative bond to the Cu atom to produce a square-pyramidal geometry at the metal center, while the second is linked to the Cu atom of the adjacent molecule, giving an N₂O₄ octahedral coordination arrangement. For the second Buⁱ-substituted complex, Cu[OC(CF₃)₂CH₂NHBuⁱ]₂, the X-ray structural analysis demonstrated an N₂O₂ square-planar geometry, with one alkoxide oxygen atom forming strong H-bonding to an adjacent water molecule. Metal CVD experiments were carried out, showing that the source reagents Cu[OC(CF₃)₂CH₂NHBuⁱ]₂, Cu[OC(CF₃)₂CH₂NHBu^t]₂, and Cu[OCMe(CF₃)CH₂NHBuⁱ]₂, which possess a secondary amino group, are capable of depositing copper metal at temperatures of 250–300 °C under inert Ar carrier gas, while Cu[OCMe(CF₃)CH₂NMe₂]₂, with a tertiary amine group, requires the use of reductive H₂ carrier gas to induce metal deposition at lower temperatures.