Liquid injection MOCVD of TiO 2 and SrTiO 3 thin films from [Ti(OPr i ) 2 (tbaoac) 2 ]: Film properties and compatibility with [Sr(thd) 2 ] Reji Thomas a , Raghunandan Bhakta b , Peter Ehrhart a , Roland A. Fischer b , Rainer Waser a , Anjana Devi b, ⁎ a IFF-Institut für Festkörperforschung and cni-Centerof Nanoelectronic Systems for Information Technology, Forschungszentrum Jülich, D-52425 Jülich, Germany b Inorganic Materials Chemistry Group, Lehrstuhl für Anorganische Chemie II, Ruhr-University Bochum, D-44780 Bochum, Germany Available online 21 April 2007 Abstract Different mixed alkoxide β-ketoester Ti precursors were synthesized and titanium bis (isopropoxide) bis (tert-butylacetoacetate) was selected for detailed CVD studies of TiO 2 and SrTiO 3 films. Films were deposited on Pt/ZrO 2 /SiO 2 /Si substrates and special emphasis was directed on low deposition temperatures (≤ 500 °C). TiO 2 films were amorphous for deposition temperatures ≤ 450 °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. SrTiO 3 films could be grown within the wide temperature range from 450 to 700 °C. High growth rates and (100) textured films were achieved at T ≥ 600 °C. However, at lower temperature (450–500 °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. © 2007 Elsevier B.V. All rights reserved. Keywords: Metalorganic precursors; β-ketoesters; MOCVD; TiO 2 ; SrTiO 3 1. Introduction Titanium dioxide (TiO 2 ) finds a broad spectrum of potential applications and Ti is one of the main components of high-κ and ferroelectric materials such as SrTiO 3 , (Ba,Sr)TiO 3 , and Pb(Zr, Ti)O 3 , which are considered for the fabrication of ultra high density dynamic random access memories (DRAM), non- volatile computer memories (NVRAM), sensors, and IR detectors [1–5]. Among the various methods employed for the deposition of thin films, chemical vapor deposition (CVD) has some inherent advantages namely conformal coverage over non planar structures, direct control over composition and the possibility of large area deposition with high uniformity [6–8] and liquid injection metal organic chemical vapor deposition (LI-MOCVD) has special advantages for the precursors, which are solid at room temperature, especially for the rare earth metals. In case of multicomponent materials it is necessary to design evenly matched individual precursors with regard to their evaporation and decomposition characteristics and molecular chemistry offers this flexibility [9–11]. Much progress has been achieved in the MOCVD of oxide thin films and the authors had previously deposited (Ba,Sr)TiO 3 films with the commercially available precursors, Sr(thd) 2 , Ba(thd) 2 and [Ti(OPr i ) 2 (thd) 2 ] in an AIXTRON 2600G3 planetary reactor, which is used also for the present investigation [12,13]. Deposition were done over a broad temperature range and high quality films could be grown at a temperature above 600 °C [14]. This temperature is very high for the process flow employed in the DRAM semiconductor industry for the stacked capacitor and hence a compatible thermal budget (≤ 500 °C) is of great importance. As precursors play a crucial role in the deposition characteristics, we started to investigate new modifications of the Ti precursors. Mixed alkoxide β-ketoester precursors are considered as promising candidates, and we tested differ- ent combinations by varying the alkoxide moieties as well as the β-ketoester ligand systems [15]. Due to the improved ther- mal properties we selected the β-ketoester complex [Ti(OPr i ) 2 (tbaoac) 2 ] (tbaoac = tert.but. acetoacetate) for detailed deposi- tion tests. Surface & Coatings Technology 201 (2007) 9135 – 9140 www.elsevier.com/locate/surfcoat ⁎ Corresponding author. Tel.: +49 234 3224150; fax: +49 234 3214174. E-mail address: anjana.devi@rub.de (A. Devi). 0257-8972/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.surfcoat.2007.04.038