Mononuclear Mixed beta-Ketoester-alkoxide Compound of Titanium as a Promising Precursor for Low-Temperature MOCVD of TiO(2) Thin Films

Titanium dioxide (TiO(2)) finds a broad spectrum of potential applications in areas such as photovoltaics, photocatalysis, and gas sensors, and has been proposed as an alternative to SiO(2) gate dielectrics. Added to this, TiO(2) forms one of the main components of high-k and ferroelectric materials such as SrTiO(3), (Ba,Sr)Ti(3), and Pb(Zr,Ti)O(3), which are considered for the fabrication of ultra-high density DRAMs, non-volatile computer memories, sensors, IR detectors, etc. Among the various methods employed for the fabrication of thin films, CVD is preferred because of some inherent advantages. The most widely used CVD precursors for the deposition of TiO(2) are titanium tetrachloride [TiCl(4)] and titanium alkoxides [Ti(OR)(4), R = (i)Pr, (t)Bu, Et]. However, because of the various limitations of these precursors such as toxicity, high moisture sensitivity, and poor matching of the thermal decomposition character with co-precursors, much of the work has been directed towards improved and molecularly tailored alternative precursors. The key concept is to combine alkoxide ligands with intramolecular adduct formation and/or beta-diketonate type chelating ligands leading to more sophisticated heteroleptic complexes as precursors.