A review is given of ceramic and single-crystal thin film ferroelectric oxides, emphasizing perovskite phases, together with some new developments on hafnia films. It is shown that singlecrystal barium titanate films behave as bulk down to at least 77 nm, with no finite size effects, no phase transition temperature shifts, and no dielectric peak broadening or change from first-to second-order transitions, suggesting that the gradient defect model of Bratkovsky and Levanyuk correctly describes such effects as extrinsic in experimental studies of equally thin ceramic thin films. In ceramic barium-strontium titanate (BST) thin films, it is shown that there is also no intrinsic broadening or shifts in phase transitions, with sharp, unshifted, bulk-like transitions observed only as re-entrant upon warming from cryogenic temperatures; this shows that phase transitions in ceramic thin films are dominated by kinetics and not thermodynamics and are definitely not equilibrium measurements. At high fields (41 GV/m), the films exhibit space charge-limited conduction; no variable-range hopping is observed, contrary to recent studies on SrTiO 3 . Some novel, unconventional switching processes are discussed, comparing the ''perimeter effect'' (non-equilibrium, ballistic) with Molotskii's equilibrium model. Theory and experiment are described for [3D] nanotubes, nanorods, and nanoribbons (or micro-ribbons). The layered-structure-perovskitepyrochlore conversion in bismuth titanate is described together with the PbO1TiO 2 phase separation in lead zirconate titanate during electrical breakdown, as are novel HfO 2 precursors that demonstrate enhanced temperature crystallization from the amorphous state and hence commercial advantages for frontend processing. II. [2D] SystemsIn planar structures, both fine-grained ceramics and single crystals offer intriguing materials science in the 4-100 nm thickness regime. Several authors 2-4 have indicated that thin films might exhibit second-order phase transitions that, in bulk form, are first order; then, the question is exactly what thicknesses constitute ''thin''? Although the International FRAM ''Roadmap'' suggests 5 that FRAM structures must become [3D] by 2007 to accommodate requisite capacitance, at present, all FRAMs are planar-stacked devices. Therefore, we begin with the [2D] systems' materials science. J ournal

The broad use of ferroelectric oxide films as capacitors in dynamic random access memories (DRAMs) has been developed, and ferroelectric random access memories (FeRAMs) are now also important commercial products as non-volatile memories. [1] Considerable ferroelectrics research has been focused on growth in integration density of FeRAMs, with the latest commercial device in production an 8 Mb PZT memory from Texas Instruments. However, all FeRAMs are still planar-stacked devices, even though the International FeRAM Roadmap [2] suggests that FeRAM structures must become three-dimensional (3D) by 2010 to accommodate requisite storage density.

We report conformal deposition of both RuO2 electrodes and PbZrxTi1−xO3 (PZT) capacitors in submicron Si trenches through the same in situ liquid source mist processing. The step coverage for the RuO2 electrodes is 75% at 225 °C. After electroding, we deposited Pb(Zr,Ti)O3 thin films and nanotubes using the same apparatus with remanent polarization of ∼15 μC/cm2. The step coverage was 59% on the sidewall and 79% on the bottom wall. Electrical testing showed charge storage (capacitance/trench) was 13±2 pF, with a breakdown voltage of 11.3±0.2 V and dielectric constant ε=166±30. This shows that a single inexpensive processing can produce fully electroded dynamic random access memory trenched capacitors with high aspect ratios and commercial electrical performance.

We report on structural and electrical properties of tantalum penta oxide (Ta2O5) material with a high dielectric constant grown from a penta ethoxy tantalum [Ta(OC2H5)5] liquid source by the plasma-enhanced liquid source chemical vapor deposition (PE-LS-CVD) technique. We have investigated several basic plasma deposition conditions. Structural properties investigated by θ-2θ X-ray measurements showed the amorphous nature of the films, and Auger electron spectrosopy (AES) and secondary ion mass spectroscopy (SIMS) indicated growth of Ta2O5 films having proper stoichiometry (Ta/O=0.4). Optical transmission spectroscopy showed that the band gap (E g) of Ta2O5 is 5.28 eV. Electrical measurements performed on Au/Ta2O5/n, p-Si metal oxide semiconductor (MOS) structure exhibited very well defined capacitance-voltage (C-V) characteristics with flat band voltage as low as -0.1 eV, low leakage current, high breakdown voltage and high dielectric constant (25-38). As a hitherto unreported step in Ta2O5 processing we also performed rapid thermal (RTA) annealing at 700°C and 900°C for 5 min which resulted in much improved electrical properties. All results suggest growth of high-quality Ta2O5 films from a carbon-based Ta liquid source, due to an effect of plasma-enhanced deposition process.

The characteristics of plasma parameters and their spatial structures in a parallel-plates RF discharge in argon modified by the injection of small carbon particles have been investigated. A larger peak-to-peak fluctuation of space potential in the bulk plasma region was observed by an emissive probe measurement together with a decrease in the self-bias voltage. The electron energy distribution function in the plasma bulk as measured by an energy analyser also showed the prwence of a higher energy tail. The enhancement of an argon atomic line emission in the midgap was consistent with the above results, showing the transition of the discharge mode from the gamma to alpha regimes. Spatial and temporal behaviours of paliicle density and size were measured by a newly proposed ellipsometric detection method of the laser Mie scattered light. Slow shift of the peak position of density and size distributions towards the sheath edge of the powered electrode was observed.