New Volatile Perfluorinated Amidine-Carboxylate Copper(II) Complexes as Promising Precursors in CVD and FEBID Methods

In the present study, we have synthesised and characterised newly copper(II) complexes with the general formula [Cu-2(NH2(NH=)CC2F5)(2)(mu-O2CRF)(4)], where R-F = CF3, C2F5, C3F7, C4F9. Infrared spectroscopy, mass spectrometry with electron ionisation (EI MS), and density-functional theory (DFT) calculations were used to confirm compounds' composition and structure. The volatility of the compounds was studied using thermal analysis (TGA), EI MS mass spectrometry, variable temperature infrared spectroscopy (VT IR), and sublimation experiments. Research has revealed that these compounds are the source of metal carriers in the gas phase. The thermal decomposition mechanism over reduced pressure was proposed. TGA studies demonstrated that copper transfer to the gaseous phase occurs even at atmospheric pressure. Two selected complexes [Cu-2(NH2(NH=)CC2F5)(2)(mu-O2CC2F5)(4)] and [Cu-2(NH2(NH=)CC2F5)(2)(mu-O2CC3F7)(4)] were successful used as chemical vapour deposition precursors. Copper films were deposited with an evaporation temperature of 393 K and 453 K, respectively, and a decomposition temperature in the range of 573-633 K without the use of hydrogen. The microscopic observations made to investigate the interaction of the [Cu-2(NH2(NH=)CC2F5)(2)(mu-O2CC2F5)(4)] with the electron beam showed that the ligands are completely lost under transmission electron microscopy analysis conditions (200 keV), and the final product is copper(II) fluoride. In contrast, the beam energy in scanning electron microscopy (20 keV) was insufficient to break all coordination bonds. It was shown that the Cu-O bond is more sensitive to the electron beam than the Cu-N bond.

Automated summary

The study synthesized and characterized new copper(II) complexes and investigated their composition, structure, thermal decomposition mechanism, and application as chemical vapour deposition precursors. The research confirmed that the copper complexes act as a source of metal carriers in the gas phase and demonstrated their successful use in depositing copper films without the use of hydrogen. Microscopic observations revealed the sensitivity of Cu-O bond to the electron beam in comparison to the Cu-N bond.