Thermal conversions of some Ba, Sr, Ti oxide precursors for CVD

Gas phase composition and conversions under evaporation and thermal decomposition of Sr(dpm)2, Ba(dpm)2, TiO(dpm)2 and Ti(OPri)2(dpm)2 (dpm=C(CH3)3COCHCOC(CH3)3, Pri = CH(CH3)2) which are conventional CVD precursors for BST films have been studied by means of original mass spectrometric technique. Properties and thermal behaviour of these compounds have been compared with respect to CVD precursor. It has been shown that conversions leading to binuclear species formation occur under transportation of TiO(dpm)2 into deposition zone. It has been reported alike decomposition mechanism of Sr and Ba precursors. Influence of oxygen on thermal stability and products of decomposition of the source compound has been shown

General aspects of surface chemistry of metal β-diketonates

Chemical reactions of metal β-diketonates, which are conventional CVD precursors, on hot surface, have been considered. Extensive experimental data on thermal behaviour of metal β-diketonate vapours obtained by hightemperature mass spectrometry have been generalized. The influence of different gas reagents on thermal stability of the compounds has been discussed. The main mechanisms of the decomposition of compounds under investigation, leading to metal and oxide formation on hot surface, have been established. Application of mass spectrometric data to the optimization of CVD processes (precursor choice, temperature range of deposition) has been shown. A possibility to predict film composition using the data on gaseous decomposition products has been considered

Mass Spectrometric Study of Copper(II) β-Diketonates Vapour Thermolysis Mechanism and Kinetics

Vapour thermolysis processes of copper(II) bis-chelate complexes with different β-diketones in the 160-640°C temperature range were studied by using the high-temperature source of a molecular beam with mass spectrometric recording of the gas phase composition directly at the outlet from the thermal reactor. Schemes of a heterogeneous decomposition of these compounds vapour were suggested on the basis of temperature dependences of the thermolysis gaseous products composition. It was established that the mechanisms of thermal conversion of copper(II) complexes with fluorinated and non-fluorinated ligands were not similar. A comparison of the thermal behaviour of the complexes with fluorinated and non-fluorinated ligands in vacuum, hydrogen and oxygen was carried out. Effective values of kinetic parameters in the Arrhenius equation were calculated for the first-order reaction on initial compound from the temperature dependence of the rate constant. The sequence of copper(II) complexes with β-diketones having different end substituents according to the thermal stability was revealed from the values of the thermal decomposition activation energy

Mass Spectrometric Study of Thermolysis Mechanism of Metal Acetylacetonates Vapour

The processes of thermal decomposition of aluminium(III) and scandium(III) acetylacetonates (Al(aa)3 and Sc(aa)3) were investigated in the 160-650°C temperature range using a high-temperature molecular beam source with mass spectrometric sampling of the gas phase composition directly at the outlet from the reaction zone. A scheme of thermal decomposition of aluminium(III) and scandium(III) acetylacetonates vapour is suggested. It is established that the common mechanism of thermolysis of these complexes is due to the commonness of electronic structure of ions Mg2+, Al3+, Sc3+ and Hf4+. According to the scheme, the process proceeds along three parallel routes, one of them being possible only for complexes possessing more than two ligands ; in this case the gaseous products resulting from cyclic dimerization of ligand fragments are formed. The influence of oxygen and hydrogen on the composition of the gaseous products and the mechanism of thermolysis of the complexes vapour are also established. From temperature curves, the effective values of kinetic parameters in Arrhenius equation are calculated for the first order reaction

Routes of metal oxide formation from metal β-diketonates used as CVD precursors

Thermal decomposition mechanism of a number of metal β-diketonates commonly used in CVD has been studied by means of original mass spectrometric technique. Regularities of thermal decomposition of non-fluorinated β-diketonates on hot surface in the absence of intermolecular interactions in the gas phase have been established. Occurrence of the competitive processes of metal and oxide formation is revealed. Routes have been proposed, leading to the formation of metal oxides in the condensed phase in the absence of oxygen under the conditions of collision-free heterogeneous process. Schemes of thermal decomposition with the assumed rearrangements are suggested. Influence of oxygen on thermal stability and products of decomposition of the initial source compound has been shown