Liquid injection MOCVD of TiO2 and SrTiO3 thin films from [Ti(OPri)2 (tbaoac)2]:: Film properties and compatibility with [Sr(thd)2]

Different mixed alkoxide beta-ketoester Ti precursors were synthesized and titanium bis (isopropoxide) bis (tert-butylacetoacetate) was selected for detailed CVD studies of TiO2 and SrTiO3 films. Films were deposited on Pt/ZrO2/SiO2/Si substrates and special emphasis was directed on low deposition temperatures (<= 500 degrees C). TiO2 films were amorphous for deposition temperatures <= 450 degrees C and crystallized in the tetragonal anatase structure above that. The film growth was homogeneous over large areas and columnar growth was found for the crystalline films. SrTiO3 films could be grown within the wide temperature range from 450 to 700 degrees C. High growth rates and (100) textured films were achieved at T >= 600 degrees C. However, at lower temperature (450-500 degrees C), stoichiometry is strongly influenced by a decrease of the Ti incorporation efficiency. This effect could be attributed to the interaction with the Sr precursor and could be avoided only by long separation times between the Ti and Sr injection pulses. (C) 2007 Elsevier B.V. All rights reserved.