We have systematically varied processing parameters to fabricate PZT 53/47 thin films. Polycrystalline PZT thin films were fabricated by spin depositing Pt coated Sio2/Si substrates with alkoxide solutions. Our study focused on two process parameters: 1) heating rate and 2) excess Pb additions. We used rapid thermal processing techniques to vary heating rates from 3°C/min to 8400°C/min. Films were characterized with the following excess Pb additions: 0, 3, 5, and 10 mol% For all process variations, films with greater perovskite content had better ferroelectric properties. Our best films were fabricated using the following process parameters: an excess Pb addition of 5 mol%, a heating rate of 8400°C/min and annealing conditions of 700°C for 1 min. Films fabricated using these process conditions had a remanent polarization of 0.27 C/m2and a coercive field of 3.4 MV/m.

PbTiO3 thin layers were deposited onto GaAs by sol-gel processing. The GaAs substrates were encapsulated with Si3N4 or SiO2 to minimize diffusion problems. Gel layers were heat treated to 350°C for removal of organic species and for the densification of the amorphous gel structure. Rapid thermal processing at 600°C was used to crystallize PbTiO3 into the perovskite structure. SIMS analysis determined limited diffusion of Ga and As into PbTiO3. The fine grain microstructure contained domains.

Alkoxide-based solutions were synthesized and used to prepare Pb[(Mg1/3Nb2/3)0.90Ti0.10]O3 (90PMNT) thin layers on platinized Si. A multilayering spin casting method was used. The effects of preparation procedure, additives, and intermediate heat-treatments on perovskite phase content, microstructure development and dielectric properties are reported. The greatest perovskite content (∼99%) and the best dielectric properties (K ≈ 1500–2000, tan∂ ≈ 0.03 at 100 kHz) resulted from rapid thermal processing of individual layers at 800°C. Polarization-reversal measurements are also reported.

Thin films of ferroelectric and piezoelectric materials are playing a growing role as critical elements in microwave acoustic devices, infrared imagers, integrated optic circuits, optical displays and high-performance semiconductor memories. In this review, we discuss recent progress in the control of growth, structure and properties of the main candidate materials, such as piezoelectric ZnO and AlN, and ferroelectric PZT-based solid solutions, KNbO3, bismuth titanate (Bi4Ti3O12), LiNbO3, LiTaO3 and KNO3. Brief mention is also made of the role and status ferroelectric polymers and of the BaMF4 class of fluorides. The emphasis of the review is primarily on vacuum-processed films, and optimization of characteristics required for integration into solid-state or semiconductor components.

Thin film ferroelectric structures are being investigated for use as storage capacitors for Non-volatile Random-Access Memories. To integrate ferroelectrics with standard silicon semiconductor processing, a great deal of effort must be spent identifying compatible materials. These materials must be able to withstand both ferroelectric and silicon processing steps involving different temperatures and environments.

In this paper we have used Rutherford backscattering spectrometry (RBS) to study the diffusion of ferroelectric Pb(Zr.5Ti.5)O3 elements into thin films of TiOx, TiNx, ZrNx and ZrOx deposited onto thermally grown SiO2. The sample matrix was annealed at various temperatures in argon ambient and analyzed using 2 MeV He+. Diffusion profiles (concentration vs. depth profiles) of the ferroelectric constituents were determined for the different barrier films. Results indicated that ZrN is the most promising barrier layer so far, having shown the least interdiffusion at 700°C.

The stresses in rf sputtered BaTiO3 thin films, deposited on both Si and sapphire single crystals, were studied. From the measured total film stress values, both the intrinsic stresses in the film and the elastic coefficients [Ef/(1–vf)] of the film were obtained. BaTiO3 films can be obtained in any stress state (tensile, stress free or compressive) by varying the deposition temperature, deposition pressure, and substrate. At lower temperatures and pressures compressive intrinsic stresses were observed whereas, at high deposition temperatures and pressures intrinsic stresses were tensile in nature. The [Ef/(1–vf)] value approached the single crystal value for films deposited at low pressures and decreased significantly with increasing deposition pressure.

The development of integrated electronic devices has resulted in an increased interest in the study of ferroelectric ceramic films on silicon prepared by diverse methods. Some of these studies aim at the development of films whose ferroelectric properties equal or approximate those of the bulk ceramic. It is therefore important to attain a better understanding of the microstructure of these films and the relationship between the microstructure and the different film preparation methods. This study examines the strain field in such a film as a function of annealing time. The technique chosen was grazing incidence x-ray scattering (GIXS), and the material, thin films of BaTiO3 deposited on silicon (111) single crystals by metallo-organic deposition (MOD). The BaTiO3 {110} and {101} reflections were monitored. A substantial relaxation of the d-spacing of planes parallel to the surface was measured after a 64 hour annealing. The d-spacing of planes perpendicular to the surface remained essentially unchanged.

Potential applications for ferroelectric thin films include both electronic and optoelectronic devices. In order to integrate a large number of devices on a single ceramic film or to incorporate ceramic devices with silicon-based integrated circuits, suitable film patterning techniques must be developed. In this study, the use of plasma etching for device patterning of PLT thin films has been explored using a dc hollow cathode discharge with HCl and CF4 etching gases. At room temperature, no etching of material is discernable. As the substrate temperature is increased, however, relatively rapid etching takes place. Etch rates for PLT thin films as high as 6500 Å/hour were measured. Etching occurred in both chlorinated and fluorinated plasmas, but at considerably different rates. The etch rate is enhanced by a factor of six by using a combination of HCl and CF4 in the plasma. After etching, the stoichiometry of the film, measured by energy dispersive spectroscopy (EDS), varied greatly with changes in substrate temperature. Although the removal rate for each element is different, all traces of lead, titanium, and lanthanum can be removed from the substrate over a wide range of plasma etching conditions.

Ferroelectric PZT thin films were prepared by sol-gel methods and RF magnetron sputtering. Sputtered PZT fast fired at 650° for 30 minutes showed microporosity. For the sol-gel route, solution precursors had a significant effect on the microstructure of the crystalline PZT films. PZT thin films derived from metal-organic precursors dissolved in n-propanol were observed to have large and microporous spherulitic grains on the order of 2 μm and phase separation in acetic acid-catalyzed films. In contrast, PZT precursors originated from alcohol exchanges with 2-methoxyethanols resulted in dense films with fine grains of ∼0.2 μm and clear evidence of ferroelectric domains. The dense sol-gel films possessed superior dielectric and ferroelectric properties.

The ferroelectric domain structure in sputtered lead zirconate titanate (PZT) thin films has been investigated using transmission electron microscopy (TEM) and transmission electron diffraction (TED). The individual ferroelectric domains occur as {110}-type microtwins as is observed in the bulk ceramic. The arrangement and size of the ferroelectric domains is strongly dependent on the microstructure of the sputtered film.

Ferroelectric thin films are now being used in conjunction with semiconductor CMOS technology to produce non-volatile IC memory devices. Three film compositions across the lead-zirconate-titanate (PZT) phase diagram were examined by transmission electron microscopy (TEM). The films are produced using organo-metallic sol-gels and sintered using standard semiconductor processing techniques. The grain structure of these thin films differ greatly from bulk ceramic crystals and thin films prepared using other deposition techniques. For two compositions, Pb1.1 (Zr0.75Ti0. 25)O3 and Pb1.1 (Zr0.50Ti0.50)O3, the perovskite structure was found in large rosettes surrounded by the polycrystalline pyrochlore phase. In the Pb1.1(Zr0.25Ti0.75)O3 sample, perovskite grains were found with no evidence of the pyrochlore phase. Ferroelectric domains were imaged in all three samples.

Barium titanate (BaTiO3) is of interest for use in a number of thin-film applications in electronic and optoelectronic devices. For these devices the formation of epitactic films of the correct stoichiometry and phase is essential. The substrate is important during the early stages of growth in the establishment of epitaxy, factors such as lattice mismatch, surface preparation and crystallographic orientation can all affect film nucleation and growth. In this study thin-films of BaTiO3 have been formed using the pulsed-laser ablation technique. The early stages of film growth have been studied directly using transmission electron microscopy by examination of very thin films deposited onto specially prepared electron-transparent thin-foil substrates.

SrTiO3 thin film preparation onto Si substrates using RF magnetron sputtering has been studied for a high capacitance density required for the next generation of LSI's. Structural and chemical analysis on the interface between SrTiO3 film and Si was carried out with cross-sectional TEM, EDX, and AES. Dielectric properties were measured on AuTi/SrTiO3/Si/Ti/Au capacitors. The as-grown dielectric films on Si were analyzed and found to consist of three layers; SiO2, amorphous SrTiO3 and crystalline SrTiO3, from interface toward film surface. By annealing at 600 °C, the amorphous SrTiO3 layer was recrystallized, and consequently the capacitance value increased. A typical specific capacitance was 4.7 fF/μm2 and the leakage current was in the order of 10−8 A/cm2, for 180 nm thick SrTiO3 film. The dielectric constant decreased from 147 to 56 with decreasing SrTiO3 film thickness from 480 nm to 80 nm. This is due to the low dielectric constant SiO2 layer (ε=3.9) at the interface. From the film thickness dependence of the ε value, the SiO2 layer thickness was calculated to be 3.9 nm, which agreed well with the value directly observed in the TEM.

To avoid SiO2 layer formation, barrier layers between SrTiO3 and Si have been studied. Among various refractory and noble metals, RuSi and a multi-layer of Pt/Ti have been found to be promising candidates for the barrier material. When RuSi film or Pt/Ti film was formed between SrTiO3 film and Si substrate, dielectric constant of about 190 was obtained in dependent of the SrTiO3 film thickness in the range of 80–250 nm. Analysis on the barrier layers was performed by means of RBS, XPS and XRD.

The interface between ultrathin sputtered lead zirconate titanate (PZT) films and a conductive electrode (indium tin oxide-ITO) is investigated. Structural and compositional changes at the PZT-ITO interface have been examined by surface analysis and depth profiling techniques of glancing angle X-ray diffraction, Rutherford backscattering (RBS), SIMS, Auger electron spectroscopy (AES), and elastic recoil detection analysis (ERDA). Studies indicate significant interdiffusion of lead into the underlying ITO layer and glass substrate with a large amount of residual stress at the interface. Influence of such compositional deviations at the interface is correlated to an observed thickness dependence in the dielectric properties of PZT films.

The electro-optic properties of sputter-deposited PLZT, BaTiO3, SBN, and BNN films on fused silica substrates have been studied using a confocal scanning optical polarization microscope. The Pockels, Kerr, and higher order electro-optic coefficients and their relations to the non-linear optical coefficients in the films are presented. The materials and physical properties of the films are discussed.

Electron spectroscopy for chemical analysis (ESCA) is well suited for investigating the surfaces of ferroelectric films. More importantly, this technique is valuable for ferroelectric films because, reduction of ions, such as Pb2+, Bi3+, and Ti4+ by photon beam is much less likely than probing electron and ion beams which are used in other methods. In the present paper a brief description of the possibilities of ESCA for determining qualitative and quantitative surface composition, and thickness of extremely thin films was presented. Special emphasis was given to multicomponent films, such as lead zirconate titanate (PZT). Factors that lead to considerable difference in the composition of the surface were discussed. Different depth profiling techniques using ESCA were also presented.

Typical fatigue and aging characteristics are reported for thin PZT films prepared using sol-gels. The fatigue process occurs in two steps. There is an initial period, during which the domain matrix of the as formed film is restructured by the cycling and the polarization generally increases, followed by a period in which the polarization decays. The polarization decay may be due, in part, to the formation of dielectric layers at the electrodes. The effects of voltage and temperature on fatigue are reported. Aging is examined as a function of temperature. Measurements of internal bias fields do not support the view that they are the primary cause of aging. Neither fatigue nor aging are temperature sensitive making identification of specific physical processes difficult.

Small signal dielectric response is reported for a variety of PZT thin film samples. Small and large signal responses, recorded simultaneously during the fatiguing of PZT thin films, are used to identify distinct fatigue mechanisms. Microcracking or electrode delamination less than 100 Å is sufficient to explain the high correlation between the dielectric permittivity and remanent polarization during fatigue.

PZT is a well known ferroelectric material which has been investigated in thin film form for memory, electro-optical and actuator applications. The electrical and electro-mechanical properties of thin PZT films deposited by opposed target RF-sputtering and laser ablation were determined. The targets were sintered and one of them had a composition near the morphotropic phase boundary (48% Ti and 52% Zr) while the other one was on the tetragonal side of the phase diagram with 60% Ti and 40% Zr. Both types had 25% excess lead. The thin films were deposited on a number of substrates (MgO, CaF2, Al2O3 and Spinel. Platinum electrodes were e-beam evaporated on Si/SiO2 as well as on the above single crystal materials). We have measured the relative dielectric constant ε, the polarization P and the electrical field to mechanical strain conversion factor d33. The values which were obtained are compatible with bulk materials but an annealing step at 575°C in oxygen is necessary after deposition. The values before anneal are often significantly lower and we have attributed the reduction to interface layers between the electrodes and the perovskite film or a surface layer on the grains. The d33 coefficients were determined by an interferometric technique which directly detects the surface displacement of the electrode dot.

Modified lead titanate ferroelectdc thin films are currently utilized in conjunction with silicon CMOS technology for non-volatile memory applications. The electrical measurement of ferroelectric films has been common practice for many years but the parameters necessary for optimizing their use as memory have not been routinely recorded. Remanent polarization, spontaneous polarization and their change through fatigue and ageing are still the dominant parameters but the pulsing conditions of interest are driven by the circuit requirements. The operation of a memory circuit will be discussed along with implications for testing. Memory is written by applying a pulse to the capacitor. It is read by applying a pulse and sensing whether or not the polarization switched. Read and write pulses will apply different voltages to the ferroelectric capacitor in the circuit because a sense capacitor will be in series with it during the read. A new test, pulsed hysteresis, which is based on circuit operation will be presented. Parameter space of interest will also be discussed.