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

Volatile low-melting CuII metal complexes of formula Cu[OC(CF3)R1CH2NHR2]2 (R1 = CF3 or CH3; R2 = CH2CH2OMe, Bui, or But) 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)2CH2NHBut]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.