Innovative second-generation Ba and Sr precursors for chemical vapor deposition of Ba1-xSrxTiO3 thin films

Ba1-xSrxTiO3 (BST) thin films, appealing candidates for innovative applications in microelectronics, have been obtained by chemical vapor deposition using innovative second-generation Ba and Sr molecular precursors, namely, [Ba(thd)2(pmdien)(Meim)] (thdH = 2,2,6,6-tetramethyl-3,5-heptanedione; pmdien = N,N,N',N",N"-pentamethyldiethylenetriamine; Meim = methylimidazole) and [Sr2(thd)4(imH)2(EtOH)] (imH = imidazole). Titanium tetra-isopropoxide Ti(OiPr)4 was used as Ti source. Film preparation was carried out on quartz and Si(100) substrates at 450°C under a nitrogen+oxygen atmosphere and followed by annealing in air at temperatures up to 800°C. The structural, compositional, and morphological evolution of the films was investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy, with particular focus on the interplay between the system properties and the processing conditions. The formation of nanophasic BST layers (crystallite size < 30 nm) required a minimum annealing temperature of 800°C.