NOVEL VOLATILE BARIUM BETA-DIKETONE CHELATES FOR CHEMICAL-VAPOR DEPOSITION OF BARIUM FLUORIDE THIN-FILMS

Barium bis chelates of 1,1,1,5,5,6,6,6-octafluoro-2,4-hexanedione (Hofhd) and 1,1,1,5,5,6,6,7,7,7-decafluoro-2,4-heptanedione (Hdfhd) have been synthesized. The volatilities of these compounds were investigated by isothermal thermogravimetric analysis (ITG) and mass spectroscopy. The new chelates sublimed in a lower temperature region (190-220-degrees-C) and exhibited better thermal stability than conventional fluorinated barium chelates, barium hexafluoroacetylacetonate [Ba(hfa)2] or barium heptafluorodimethyloctanedionate [Ba(fod)2]. They were applied to the low-pressure chemical vapor deposition (CVD) of barium fluoride (BaF2) thin films. Under an oxidizing condition, impurity-free and strongly (111)-axis-oriented BaF2 films were deposited onto a silica substrate.