Vapor pressure of precursors for CVD on the base of platinum group metals

Metal beta-diketonates are broadly used in the processes involving deposition of different types of coatings by CVD. Acetylacetonates of platinum group metals are the most suitable precursors for use in highly effective CVD processes because of their thermal properties, low price of initial ligand and accessible synthesis methods. Much attention is given to the investigation of such an important property as volatility, which is necessary to optimize the parameters of coating deposition. At present, a lot of experiments studying temperature dependencies of saturated vapor pressure of volatile metal chelates have been carried out by different methods. However, the data on vaporization parameters often do not coincide with each other. In order to consider the reasons of such, differences, we measured the temperature dependencies of saturated vapor pressure of acetylacetonates of palladium(II) (1), platinum(II) (2), rhodium(III) (3), iridium (III) (4), ruthenium(III) (5) by flow and Knudsen methods. This allowed extending the temperature range within which vapor pressure was measured. The thermodynamic parameters of phase transition from crystal to gas were calculated. The comparison with the literary data obtained by static method with the membrane zero-gauge was carried out; the differences were enunciated and explained. The results obtained in the study were co-processed. The following meanings of the coefficients A and B in equation ln P-atm = - (A/T) + B were obtained for the investigated complexes: 13425; 22,05 (1); 12737; 20,19 (2); 14290; 22,97 (3); 15391; 25,88 (4); 15228; 25,56 (5) (flow method).