O,N-coordinated Ni(II) beta-diketonate derivatives: Synthesis, thermal properties, MOCVD applications

Ni(II) β-diketonate derivatives - β-iminoketonates with general formula Ni(RC(O)CHC(NH)R1)2 (R = R1 = CH3, C(CH3)3; R = CF3, R1 = CH3, C(CH3)3; R = C(OCH3)(CH3)2, R1 = CH(CH3)2, C(CH3)3) and Ni(1,3-diaminopropane)(R2C(O)CHC(O)R3)2 (R2 = C(CH3)3, R3 = CF3, C(CH3)3) - were synthesized with high yields. The products are stable to air and moisture, and soluble in most common organic solvents. Elemental analysis, X-ray studies, and IR spectroscopy were used to characterize the synthesized compounds. The thermal properties of the compounds in the solid state were investigated by means of TG. The temperature dependence of the saturated vapor pressures was studied using the flow method. Thermodynamic parameters of the vaporization process, ΔHТ* and ΔS°Т*, were calculated. MOCVD test experiments were carried out at low pressure (10 Torr) on Ta/Si substrates using Ni(i-tmhd)2 and Ni(pda)(tmhd)2 (i-Htmhd - 2,2,6,6-tetramethyl-4-imino-heptane-2-on, pda - 1,3-diaminopropan, Htmhd - 2,2,6,6-tetramethyl-heptane-3,5-dion) as precursors. The vaporization temperatures were 120 °C for Ni(pda)(tmhd)2 and 155 °C for Ni(i-tmhd)2. The substrate temperatures were 210-350 °C. The Ni-containing films were investigated by means of X-ray diffraction analysis, SEM, and XPS.