Volatile hafnium(IV) compounds with beta-diketonate and cyclopentadienyl derivatives Original Research Article

The volatile hafnium(IV) β -diketonates: Hf(IV) acetylacetonate Hf(acac)4, Hf(IV) trifluoroacetylacetonate Hf(tfac)4, dimer of hexafluoroacetylacetonate of Hf(IV) hydroxide Hf2(OH)2(hfac)6, Hf(IV) pivaloyltrifluoroacetonate Hf(ptac)4 and Hf(IV) 2,2,6,6-tetramethylheptanedionate Hf(thd)4—as well as two bis-cyclopentadienyl Hf(IV) derivatives Cp2Hf(NEt2)2 and Cp2HfMe2 were synthesized. The substances were identified by chemical analyses, melting points, IR, NMR spectroscopy and mass spectrometry. The crystallographic study of Hf(IV) β -diketonates is reported. The thermogravimetric analysis was carried out for all compounds. By the flow method and Knudsen method, the temperature dependences of saturated vapor pressure of Hf(IV) complexes were studied and the standard thermodynamic parameters of vaporization processes View the MathML sourceΔHTo and View the MathML sourceΔSTo were calculated. Thermodecomposition processes for cyclopentadienyl derivatives in vacuum and in oxygen atmosphere were studied by high temperature mass spectrometry and gas by-products were determined. Hf(thd)4, Cp2Hf(NEt2)2 and Cp2HfMe2 were used for depositing HfO2 films in different conditions. Data of X-ray diffraction analysis have shown that HfO2 films were in a monoclinic structure. The specific resistance and permittivity of HfO2 films was calculated.