SrTa 2 O 6 thin films with thickness between 6 and 150 nm were deposited by metal-organic chemical vapor deposition in a multiwafer planetary reactor. The monomolecular precursor, strontium-tantalum-͑methoxyethoxy͒-ethoxide, was dissolved in toluene and injected by a liquid delivery system. A rather narrow process window for the deposition of stoichiometric SrTa 2 O 6 was found for this precursor at low pressures and a susceptor temperature around 500°C. Films were grown on Pt/TiO 2 /SiO 2 /Si, TiN x /Si, and SiO 2 /Si substrates. The as-deposited films were x-ray amorphous and could be crystallized by postannealing at a temperature ജ700°C. The distorted tetragonal tungsten bronze phase of SrTa 2 O 6 was dominating within a broad range of compositions ͑Sr/Ta: 0.4-0.7͒ and a perovskite-type phase was additionally observed for Sr/TaϾ 0.7 and predominated for Sr/TaϾ 1. The electrical properties have been investigated with metal-insulator-metal and metal-insulator-semiconductor capacitors after sputter deposition of Pt top electrodes. The amorphous films had a dielectric constant K in the range of 35-45 and low leakage currents. For stoichiometric SrTa 2 O 6 the dielectric permittivity reached values of K = 100-110, but the leakage currents were increased. Remarkably, the permittivity is not very sensitive to deviations from the exact stoichiometry of the SrTa 2 O 6 phase ͑Sr/Ta: 0.4-0.7͒, but a decrease to values of K = 30-40 is observed along with the transition to the perovskite phase at high Sr contents.

A monomeric titanium complex suitable for liquid‐injection MOCVD applications is synthesized and its molecular structure is determined by single‐crystal X‐ray diffraction. [Ti(OiPr)2‐(tbaoac)2] (see Figure), (tbaoac) = tertiarybutylacetoacetonate), is a volatile alkoxide‐(beta)diketonate precursor that has a low melting point and very good solubility in common organic solvents.

The microstructure and interfaces of SrTiO 3 thin films directly deposited by metalorganic chemical vapor deposition on silicon ͑001͒ substrates were investigated by means of Bragg-diffraction contrast and high-resolution transmission electron microscopy. The observation of the plan-view specimens showed that the SrTiO 3 films are polycrystalline with randomly oriented grains. An amorphous layer was observed at the interfaces between the films and the substrates. The growth kinetics of this amorphous layer was investigated in detail. The thickness showed a rapid initial increase, which is much faster than the corresponding growth of amorphous SiO 2 in the absence of precursors, and apparently approaches saturation after a short time. The thickness of the interfacial layer increases with the oxygen partial pressure during deposition and a reduction to a value acceptable for gate-oxide applications has been achieved for the minimum pressure given by the oxygen content of the present precursors. However, this comes at the cost of a dramatic increase of the carbon content of the film.

We report on the performance of a planetary multi-wafer reactor offering extremely high throughput due to the batch mode processing and a low cost of ownership. This reactor is combined with a liquid delivery system which mixes the liquid precursors from three different sources: 0.35 molar solutions of Ba(thd)* and Sr(thd), and a 0.4 molar solution of Ti(0-iPr),(thd),. The composition and microstructure of the films were routinely investigated by X-ray diffraction and X-ray fluorescence analysis. As a direct consequence of the reactor design we obtain high efficiencies for the precursor incorporation in the order of 40%. Furthermore, we obtain a high uniformity of the films over 6 inch wafers. Details of the chemistry and microstructure were investigated by secondary neutral mass spectroscopy and scanning electron microscopy. The electrical film properties are discussed in relation to microstmctural properties.