We have used the new approach to fatigue phenomenon for analysis of the switching current and C-V characteristic evolution during cycling in PZT thin films. It was shown that in accordance with theoretical predictions the rejuvenation stage precedes the fatigue one. We have demonstrated that fatigue behavior corresponds to the spreading of the internal bias field distribution function during ac switching.

The well c-axis-oriented Bi3.25La0.75Ti3O12 films with good crystallinity and good surface morphology were obtained at temperatures higher than 600°C It was also found in a Pt / 100nm-Bi3.25La0.75Ti3O12 / 3nm-Si3N4 / Si ( metal / ferroelectric / insulator / semiconductor ) structure that C-V characteristics showed a hysteresis loop with a memory window of about 1V and both the high and low capacitance values kept at zero bias voltage did not change for more than 3 hours.

Profile control, process repeatability and productivity concerns in etching Pt electrodes are reviewed specifically for application in fabricating high-density BST/Pt capacitors. The approach of using a high temperature cathode in a high-density reactive plasma chamber has produced a repeatable >85° Pt profile, stable etch rate and low particle results over a 500-wafer marathon test. A “corrosion-like” BST defect can be prevented by adding a post etch treatment to remove any corrosive residue from the wafer surface. A feasible manufacturing solution for etching BST/Pt capacitors for future high-density DRAM application is demonstrated.

Single oxide films as well as complex oxide films are intensively studied for multi-chip modules with integrated passive functions. In this paper the processing and properties of oxide films such as Ta2O5, TiO2, Nb2O5, Ta2O5 -Al2O3, Ta2O5–Nb2O5 as well as complex oxide films such as BiNbO4 and Ba1划xSrxTiO3 films will be discussed with respect to their integration into thin film functional modules.

Thin films of barium strontium titanate are fabricated on alumina by a hydrothermal method. Crystalline films are produced at temperatures as low as 60°C. The relative dielectric permittivity of films with the composition Ba0.15Sr0.85TiO3 lies in the range between 150 and 220 for low frequencies (100 kHz to 1 MHz), decreasing with frequency. The loss tangent for the films increases from 0.05 to 0.15 over the same frequency range. Relative concentrations of barium and strontium in the film are controllable through the hydrothermal reaction conditions. The surface microstructure of the films is examined.

We have investigated the structural, compositional, interfacial, surface morphological and dielectric properties of Ba0.6Sr0.4TiO3 solid solution thin films La doped from 0 to 10 mol%. The doped thin films were prepared by the metalorganic solution deposition technique using carboxylate-alkoxide precursors. After post-deposition annealing in oxygen ambient at 750 °C the films were characterized via x-ray diffraction, Auger electron microscopy, field emission scanning electron microscopy, and atomic force microscopy. The electrical measurements were achieved in the metal-insulator-metal (MIM) configuration with Pt as the top and bottom electrode. Our results demonstrated that La doping had a strong effect on the films microstructural, dielectric and insulating properties. Specifically, 1 mol% La doped BST films exhibited a lower dielectric constant, 283 and higher resistivity 31.4×1013 W-cm with respect to that of undoped BST. The loss tangent and tunability (at 100 kHz) of the 1 mol% La doped BST films were 0.019 and 21% (at E=300kV/cm) respectively.

Retention characteristics of Metal-Ferroelectric-Insulator-Semiconductor(MFIS) and Metal-Insulator-Ferroelectric-Insulator-Semiconductor(M-I-FIS) structures have been investigated both theoretically and experimentally. The simulated time dependence of capacitance for the MFIS has indicated that reducing currents through the ferroelectric and the insulator layers improves the retention characteristics more effectively than choosing the insulators with larger dielectric constants. The M-I-FIS structure has been studied in order to reduce the charge injection between the metal and the ferroelectric layer in the MFIS. The simulations have indicated that the M-I-FIS can provide much longer retention time than the original MFIS, although the experimental retention time of the M-I-FIS have almost the same as that of the MFIS.

Barium strontium titanate (BSTO) films were synthesized by the pulsed laser deposition technique (PLD) on silicon substrates at room temperature. The thin films were synthesized at ambient temperature and 30 mT oxygen partial pressure, with 300, 400 and 500 mJ/cm2 laser fluence at 5, 10 and 20 pulses per second on silicon wafer substrates. All films were subsequently post-annealed at 750°C in an continuous oxygen stream. The microstructure, crystallinity and lattice constant of the BSTO films were studied with the aid of atomic force microscopy (FEM) and Glancing Angle X-ray Diffraction analysis (GAXRD). The hardness and modulus of elasticity of the films were studied with the aid of a nanohardness indenter. The film stoichiometry was determined with the aid of Rutherford Backscattering Spectrometry (RBS). The results of this research will be combined with the results of our previous work [1, 2] on the effect of substrate temperature and oxygen partial pressure on the microstructure and properties of the BSTO films in order to construct a structural zone model (SZM) of the BSTO films synthesized by PLD.

Epitaxial ferroelectric films undergoing a cubic-tetragonal phase transformation relax internal stresses due to the structural phase transformation and the difference in the thermal expansion coefficients of the film and the substrate by forming polydomain structures. The most commonly observed polydomain structure is the c/a/c/a polytwin that relieves the internal stresses only partially. Relatively thicker films may completely reduce internal stresses if all three variants of the ferroelectric phase are brought together such that the film has the same in-plane size as the substrate. In this article, we provide experimental evidence on the formation of the 3-domain structure based on transmission electron microscopy in 450 nm thick (001) PbZr0.2Ti0.8O3 films on (001) SrTiO3 grown by pulsed laser deposition. X-ray diffraction studies show that the film is fully relaxed. Experimental data is analyzed in terms of a domain stability map.

Motivated by the growing impact of PZT film orientation on ferroelectric film properties as film thickness is scaled down, we present basic studies on orientation selection in sol-gel derived PZT films, using pre-annealed Pt/Ti electrode layers as a model electrode system. FTIR was used to study, on a real temperature scale, chemical reactions in the films during the initial thermal steps prior to crystallization. We found that the chemical structure of the pyrolyzed film has a much larger impact on orientation selection than has previously been realized. In addition to pyrolysis conditions, the ambient used for the crystallization step was found to play a crucial role in orientation selection. As film thickness decreases, excessive oxygen incorporation in the films is seen to result in the loss of the preferential (111) texture when crystallization is performed in air. By performing crystallizations in N2, 40 nm thick PZT films with a strongly preferential (111) orientation could be obtained.

We describe here a novel approach to the subject of thermoelectric devices. The current best thermoelectrics are based on heavily doped semiconductors or semimetal alloys. We show that utilization of electric field effect or ferroelectric field effect, not only provides a new route to this problem, bypassing the drawbacks of conventional doping, but also offers significantly improved thermoelectric characteristics. We present here model calculation of the thermoelectric figure of merit in thin films of Bi and PbTe, and also discuss several realistic device designs.

(Bi,La)4Ti3O12(BLT) thin films were prepared on Si(100) substrates by the pulse injection metalorganic chemical vapor deposition (MOCVD) process, in which Ti and La precursors were injected with periodic pauses while Bi precursor was supplied continuously. In case of the pulse injection method, the film composition was relatively uniform and the Bi content at the interface was relatively uniform and the Bi content at the interface was increased. The BLT films, which were deposited by the pulse injection MOCVD, showed better crystallinity and thinner ionterfacial amorphous layer than the continuous BLT films. The continuous BLT films, although measured at 1 MHz showed similar C-V characteristics to those measured at low frequency region, and their flatband voltages also shifted severely to the negative voltage direction. On the other hand, the pulse BLT films exhibited clockwise ferroelectric hysteresis in the C-V curves. The memory window and the leakage current density were about 2V and 1.46×10−7 A/cm2 at 9V (180 kV/cm), respectively.

A very high-resolution scanning nonlinear dielectric microscope with nanometer resolution was developed for the observation of ferroelectric polarization. We demonstrate that the resolution of the microscope is of a sub-nanometer order by measurement of domains in PZT and SBT thin films. The experimental result shows that nano-sized 180° c-c ferroelectric domain with the width of 1.5 nm for PZT thin film are observed. The result also shows that the resolution of the microscope is less than 0.5 nm for the PZT thin film.

We have investigated the electrophoretic deposition (EPD) as a low cost and conformal method of fabricating barium strontium titanium (BST) based composite thick films. The films were deposited at a controlled rate on platinum substrate in acetone-based slurry under electric bias. Acetone-aerosol OTS surfactant dispersion was used as dispersive medium. Conformal BST based thick films of 10-80 μm were obtained. The dielectric constant and dielectric loss factor of Ba0.60Sr0.40TiO3 and Ba0.60Sr0.40TiO3 – 20wt% compositions were 603.3 and 0.029 and 327.0 and 0.002, respectively. The low frequency electronic properties of the electrophoretic films were also compared with those of the bulk BST ceramics. In addition, the optical and the structural properties of the films are also discussed. The various techniques employed include x-ray diffraction, SEM and surface profilometer.

Both ZnO and PZT Thin Film Bulk Acoustic Resonator filters were fabricated, tested and modeled in this study. The development of an accurate Mason model allows the effect of particular parasitic components on the microwave s-parameters in the region of the series and parallel resonances to be identified. The parasitic components that limit the performance of our ZnO and PbZr0.3Ti0.7O3 Thin Film Bulk Acoustic Resonator filters are analysed. From an analysis of PbZr0.3Ti0.7O3 Thin Film Bulk Acoustic Resonator measurements values for the longitudinal acoustic velocity and electromechanical coupling coefficient can be derived. Measured PbZr0.3Ti0.7O3 Thin Film Bulk Acoustic Resonator filter responses confirm that the larger electromechanical coupling coefficients in this material compared to ZnO give wider filter band-widths.

A comparison of pulsed laser deposited PbZr0.53Ti0.47O3 (PZT) thin film capacitors with SrRuO3 (SRO) and LaNiO3 (LNO) electrodes on (001) yttria-stabilized zirconia (YSZ) and lattice matched (001) LaAlO3 substrates is presented. Both electrode materials allow for the formation of ferroelectric capacitors with large remnant polarization (20-30 μC/cm2) and negligible fatigue, although slight differences arise regarding the promotion of either the rhombohedral or tetragonal phases of PZT. Far more crucial seems to be the tendency of SrRuO3 to develop a rougher surface at either small (<30 nm) or large thickness (>100 nm), and on YSZ substrates. In those cases a highly defective and possibly low dielectric interface forms between the electrode and the ferroelectric layer, resulting in greatly degraded ferroelectric performance. LaNiO3 is free from these limitations except for the cracks forming at very large thickness (>300 nm), and therefore appears as a more versatile electrode material.

Polarization degradation due to metal etch and/or photoresist(PR) strip processes has been investigated for Pt/SrBi2Ta2O9(SBT)/Pt ferroelectric capacitors. Interconnect metal line consisting of TiN/Al/Ti/TiN/Ti layers has been patterned by normal photolithography and plasma etch processes. We used two different sources for metal etcher, helicon or electron cyclotron resonance(ECR) source, and stripped the PR with either microwave or helicon source stripper. Polarization degradation was evaluated by measuring switching and non-switching polarization of the ferroelectric capacitors.

Neither etch machine nor etch parameters played an important role for determining polarization of the ferroelectric capacitors. Photoresist strip process, however, significantly affected the polarization of the ferroelectric capacitors. Factors affecting polarization of the ferroelectric capacitors were presence of hydrogen and plasma density during the strip process. Hydrogen atoms and protons produced by H2O or NH3 plasma penetrated through the dielectric layer and caused hydrogen induced damage. Thus the hydrogen damage was dependent on strip temperature and time. Photoresist strip with high density plasma results in charging damage to ferroelectric capacitors. It is believed that charges from the plasma are trapped at domain boundaries and interfaces, leading to polarization degradation. Damage free metal etching process for the ferroelectric capacitor was applied for the fabrication of the fully working ferroelectric random access memory.

Piezoresponse scanning force microscopy (PFM) was applied to study the nanoscale mechanism of retention loss in SrBi2Ta2O9 (SBT) thin films. Experiments were conducted by performing local polarization reversal within an individual grain with subsequent imaging of a resulting domain structure at different time intervals. The retention behavior of the films was studied as a function of switching conditions and electrode material. SFM was also used for nanoscale mapping of leakage current sites and investigation of electrical conduction mechanism at these sites. For the first time, the development of dielectric breakdown in SBT films was directly observed at nanoscale.

For the first time AgTa0.38Nb0.62O3 (ATN) films have been grown on the La0.7Sr0.3CoO3 (LSCO)/LaAlO3 single crystal as well as onto Pt80Ir20 (PtIr) polycrystalline substrate. Comprehensive X-ray diffraction analyses reveal epitaxial quality of ATN and LSCO films on the LaAlO3(001) substrate, while ATN/PtIr films have been found to be (001) preferentially oriented. Dielectric spectroscopy performed for ATN films and bulk ceramics in a wide temperature range 77 to 420 K shows the structural monoclinic M1-to-monoclinic M2 phase transition occurs in films at the temperature 60 °C lower than in ceramics. The tracing of the ferroelectric hysteresis P-E loops indicates the ferroelectric state in ATN films at temperatures below 125 K and yields remnant polarization of 0.4 μC/cm2 @ 77 K. Weak frequency dispersion, high temperature stability of dielectric properties as well as low processing temperature of 550 °C make ATN films to be attractive for various applications.

The metal organic chemical vapour deposition kinetics of Sr(hfa)2(tet) (H-hfa =1,1,1,5,5,5-hexafluoroacetylacetone and tet= tetraglyme) and Bi(C6H5)3 single precursors have been studied upon varying operational deposition parameters, namely temperature and precursor partial pressure. These precursors are of interest for the MOCVD of SBT ferroeletric thin films. Depending upon experimental conditions, deposition processes occur either in the reaction rate limited regime or in the mass transport regime. Kinetics controlled by reaction rates (T deposition< 673 K) gives insights on the process mechanisms. The activation energies of the Sr and Bi deposition processes have been determined from the Arrhenius plots.

SrBi2Ta2O9 films were grown on industrial Pt/Ti/SiO2/Si substrates and perovskite phase films were obtained after annealing in O2 environment at 1073K.