bluuebunny/crossref_metadata_2025_split huggingface dataset:
Micromechanical Analysis of Residual Stress Effect in CVD-Processed Diamond Wafer
Authors: Jeong J.-H. , Kwon D. , Lee J.-K. , Lee W.-S. , Bai Y.-J. 
Published: April 2011

AbstractDiamond wafer, considered as promising material for electronic substrate, thermal spreader, etc., has been made using deposition technology such as microwave plasma assisted CVD (MPACVD). However, high residual stress of diamond film induces bowing and throughthickness cracking in thick diamond wafer, and so hampers the economic fabrication of the wafer. Thus, to investigate the causes of bowing and cracking, the measurement of residual stress is very important. Of the residual stress, in particular, growth stress is one of the most important research topics because its effect on wafer-related problems is strong though the magnitude is relatively small. Quantification of growth stress is limited because of hightemperature plastic deformation of Si substrate. In this study, the initial growth stress without contribution of plastic deformation of substrate can be predicted through proposed beam bending stress model and numerical calculation in that plastic deformation of Si is considered. Finally, growth stress of film can be calculated from the apparent curvature of substrate measured just after deposition and the plastic curvature after diamond film removal.
On the Robustness of Scratch Testing for Thin Films: the Issue of Tip Geometry for Critical Load Measurement
Authors: Jardret Vincent D. , Oliver Warren C. 
Published: April 2011

AbstractScratch and abrasion resistance of hard protective thin films and polymer coatings is often related to their ability to withstand abrasive conditions without fracturing. Wear particles generate catastrophic and severe wear for hard films, and fractured scratches are often very visible on shiny polymer surfaces. Using a particular abrasive particle shape, the fracture resistance of a surface can be characterized by the load required to create fracture damages. The scratch technique has demonstrated its ability to create these damage mechanisms and characterize the critical load for coatings failure. However, this technique does not yet have the reproducibility and robustness required to be implemented in an industrial environment. The major reason for this lack of robustness is the great influence of the indenter geometry on critical load results and the non-reproducibility of the geometry of conical indenters. This paper addresses this issue and presents a fast and robust method to characterize the indenter geometry based on the indentation technique. Indenters, with radii smaller than 1 micron, were used to characterize thin films of different nature and thickness. The influence of tip geometry on the critical load results is presented for paint coatings. The reproducibility of the critical load measurement using different indenter tips of identical geometry, as shown in this paper, represents a considerable technological breakthrough in abrasion testing and demonstrates the scratch test's ability to control the manufacturing quality of thin films in an industrial environment.
Stress, Microstructure and Temperature Stability of Reactive Sputter Deposited Ta(N) Thin Films
Authors: Leedy K. D. , O'Keefe M. J. , Grant J. T. 
Published: April 2011

AbstractInterest in tantalum nitride thin films for use as diffusion barriers in Cu-based microelectronic interconnects merits the study of tantalum nitride thin film properties as a function of deposition conditions and elevated temperature exposure. In this investigation, the influence of nitrogen content and post deposition annealing on the stress, microstructure and resistivity of Ta(N) films was analyzed. Ta(N) thin films were deposited by reactive dc magnetron sputtering of a Ta target in Ar/N2 gas mixtures. With an increasing N2 to Ar flow ratio, the as-deposited crystal structure of the films changed from ß-Ta to bcc Ta with N in solid solution to TaN0.1 to Ta2N and finally to TaN. The as-deposited Ta(N) stress, grain size and resistivity of the films were found to be strongly dependent on the phase(s) present. Films with less than 20 at. % nitrogen concentration displayed large compressive stress increases during 650°C anneals in flowing N2. Phase transformations to Ta2N occurred after 650°C anneals in films with nitrogen concentrations from ∼ 15 to 25 at. %. Microstructural characterization using transmission electron microscopy and x-ray diffraction, and chemical analysis by x-ray photoelectron spectroscopy and Auger electron spectroscopy of the Ta(N) films were used to identify the as-deposited and transformed phases.
Room Temperature Deposition of Silicon Oxynitride Films with Low Stress Using Sputtering-Type Electron Cyclotron Resonance Plasmas
Authors: Gao D. , Furukawa K. , Nakashima H. , Gao J. , Wang J. , Muraoka K. 
Published: April 2011

AbstractSilicon oxynitride (SiOxNy) films with low stress were deposited successfully at room temperature using sputtering-type electron cyclotron resonance (ECR) plasmas. Films were deposited for a wide range of flow rate ratio of O2 to N2 at a constant Ar flow rate. Film properties were verified by characterizations of refractive index (ellipsometry), structural properties (Fourier transform infrared and Auger electron spectroscopy), intrinsic stress, and barrier strength of water penetration (thermal desorption spectroscopy). A near-stoichiometric SiOxNy (x = 1.44 and y = 0.41) film with low stress could be formed at the optimum deposition condition, under which the SiOxNy film had a refractive index of 1.54. The results of thermal desorption spectroscopy measurements showed that the SiOx Ny film had a higher barrier against moisture penetration relative to deposited SiOx and SiNy films. The SiOxNy film was directly deposited on the organic EL device and the applicability was shown clearly. These results indicate that this SiOxNy film deposited using a sputtering-type ECR plasma has the potential to be utilized as a passivation layer of organic EL devices, which are required to be formed at low temperature.
Studies of Plasticity in Thin Al Films Using Picosecond Ultrasonics
Authors: Antonelli G. A. , Maris H. J. 
Published: April 2011

AbstractWe have developed a new technique for the study of the onset of plastic flow in thin metal films. A sub-picosecond light pulse is absorbed at the upper surface of the film. This generates a strain pulse that propagates through the film to the substrate and then back to the upper surface of the film where it is detected. When the temperature of the film is changed, there is a change in the transit time of the strain pulse. This change arises from the variation of the sound velocity with temperature, and also has a contribution from thermal stress in the film. By making accurate measurements of the transit time, we are able to identify the onset of plastic flow in the film.
Hydrogen Induced Plastic Deformation of Thin Films
Authors: Pundt A. , Laudahn U. , Hüilsen U. v. , Geyer U. , Wagner T. , Getzlafft M. , Bode M. , Wiesendanger R. , Kirchheim R. 
Published: April 2011

AbstractThe mechanical behavior of a thin film that is clamped to an elastically hard substrate can be compared to a bulk metal by studying the absorption of hydrogen. Since hydrogen is dissolved in interstitial sites and exerts force on neighboring metal atoms, the in-plane stresses increase with increasing hydrogen concentration. In the case of Nb-films covered with a thin Pd layer, stresses of several GPa were measured. Nb and Pd films prepared by evaporation were loaded with hydrogen. Out-of-plane strain and in-plane stresses during electrolytic loading with hydrogen were determined by performing x-ray diffraction and substrate curvature measurements. At low H-concentrations the developing stresses correspond to a clamped film expanding elastically out-of-plane only. Above a critical H-concentration the films deform plastically. In some cases the critical hydrogen concentration corresponds to the terminal H-solubility, above which the hydride precipitates by emission of extrinsic dislocation loops. For the remaining cases a critical stress is reached before passing the phase boundary, which leads to the formation of misfit dislocations at the interface between film and substrate. The concomitant slip lines were observed on the surface of a Gd (0001) film using Scanning Tunneling Microscopy. An additional surface pattern that can be correlated with emitted dislocation loops was observed.
Plasticity in Copper Thin Films
Authors: Weihnacht V. , Brückner W. 
Published: April 2011

AbstractPlastic deformation in thin Cu films was studied by stress measurements with the wafercurvature technique during thermal cycling and in combination with four-point bending. The results from 0.5 ¼m and 1 ¼m thick Cu films are compared. In thermal cycling experiments, strengthening during cooling and a Bauschinger-like effect during reheating were observed. The stress-strain behavior investigated by four-point bending showed to be asymmetric regarding tension and compression at lower temperatures. These phenomenons are explained by a dislocation arrangement at the film-substrate interface which has formed during a previous thermal cycle.
Relation Between Macro- and Microstress in Thin Metallic Layers
Authors: Seijbel Léon J. , Delhez Rob 
Published: April 2011

AbstractX-ray diffraction has been used to measure the stress in thin nickel films. In addition to the stress value, information is obtained about the elastic interaction between grains. Various models exist to calculate the stress from the strain. A model that uses the mechanical elastic constants has been used. From this model it can be concluded that the model by Hill is applicable for the layers analyzed. Annealing experiments between 300 and 500 K show that the initially present growth stress reduces to zero at 500 K. The microstrain inside the grains is obtained from the broadening of the diffraction lines measured. During annealing the diffraction lines narrow. This is caused by two effects: grain growth and reduction of the dislocation density.
Crystal Structures, Ferroelectric Properties, and Chemical Reactions of SrBi2Ta2O9: Solid-State Chemistry of SBT Materials for FeRAMs
Authors: Shimakawa Y , Kubo Y 
Published: April 2011

AbstractWe discuss some aspects of solid-state chemistry concerning ferroelectric SrBi2Ta2O9, (SBT). Crystal structure analysis by high-resolution neutron diffraction revealed considerable structural distortion in the SBT materials. This distortion, which consists of large atomic displacements of constituent ions, causes large ferroelectric spontaneous polarization. The structural distortion is more pronounced in Sr-deficient-and-Bi-excess material Sr0.8Bi2.2Ta2O9 than in stoichiometric SBT, leading to the larger remanent polarization. The enhanced structural distortion is explained in terms of an “ionic size effect” at the A-cation site. This effect was apparently observed in a series of compounds of ABi2Ta2O9 (A=Ca, Sr, and Ba) with different size A-site cations. On the other hand, analysis of chemical reactions of SBT gave important information on the degradation of the SBT capacitors and on the reaction between the SBT materials and a Pt electrode during device fabrication. The degradation of SBT in an H2- containing reducing atmosphere and its recovery by subsequent annealing in oxygen have been reproduced experimentally by using bulk ceramics and analyzed by thermogravimetric and x-ray- diffraction measurements. SBT decomposes into Bi metal or Bi-Pt alloy in H2 by oxygen dissociation. In the presence of Pt, the SBT degradation and the re-crystallization processes differ from those for SBT alone.
Low-Temperature Processing Using Triple Alkoxide Precursors for Layer-Structured Perovskite Thin Films: Preparation and Characterization of Mbi2Ta2O9 (M: Ca or Ba) Thin Films
Authors: Kato K. 
Published: April 2011

AbstractCaBi2Ta2O9 and BaBi2Ta2O9 thin films were successfully prepared by using triple alkoxide precursors such as Ca[BiTa(OC2H5)9]2 and Ba[BiTa(OC2H5)9]2, respectively. As-deposited films were amorphous and crystallized below 500°C by rapid thermal annealing in oxygen. The crystallinity improved with annealing temperature. The development of the crystal structure and surface topography of the thin films were investigated. Additionally, some electrical properties were evaluated.
Preparation of Al Doped PZT Thin Films Using a Sol-Gel Method
Authors: Iijima T. , Sanada N. , Hiyama K. , Tsuboi H , Okada M. 
Published: April 2011

AbstractAl substitution for Zr/Ti site of PZT was attempted using a sol-gel method, and the ferroelectric properties of 200nm-thick Al doped PZT thin films were compared with those of non- doped PZT film. The leakage current of the thin films decreased with increasing Al content. Ps and Pr also decreased with increasing Al content, whereas Ec did not show a significant change. Furthermore, a simple capacitor cell structure like FeRAM was prepared using a seed layer process. The capacitor structure was Pb(Ti0.975Al0.025)O3/ Pb1.1((Zr0.52Ti0.48)0. 975Al0.025)O3/ Pb(Ti0.975Al0.025)O3, and 2Pr was 26μC/cm2. The fatigue properties of the A1 doped PZT capacitor cell showed a little improvement, because the reduction rate of the fatigue was smaller than that of non-doped PZT thin film.
Effect of Pb Excess Content on Microstructure and Electrical Properties of Sol Gel Derived PZT Thin Films
Authors: Wang Zhan-jie , Maeda Ryutaro , Kikuchi Kaoru 
Published: April 2011

AbstractLead zirconate titanate (PZT) thin films were fabricated by a three-step heat-treatment process which involves the addition of -10, 0 and 10 mol% excess Pb to the starting solution and spin coating onto Pt/Ti/SiO2/Si substrates. Crystalline phases as well as preferred orientations in PZT films were investigated by X-ray diffraction analysis (XRD). The microstructure and composition of the films were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA), respectively. The well-crystallized perovskite phase and the (100) preferred orientation were obtained by adding 10% excess Pb to the starting solution. It was found that PZT films to which 10% excess Pb was added had better electric properties. The remanent polarization and the coercive field of this film were 34.8 μC/cm2 and 41.7 kV/cm, while the dielectric constant and loss values measured at 1 kHz were approximately 1600 and 0.04, respectively. Dielectric and ferroelectric properties were correlated to the microstructure of the films.
Sputtered Pb(Zr, Ti)O3 Thin Films for Ferroelectric Capacitors
Authors: Sakoda T. , Aoki K. , Fukuda Y. 
Published: April 2011

AbstractSputtered Pb(Zr, Ti)O3 thin films with superior ferroelectric properties were successfully obtained by controlling the grain structure and the film compositions. We found that amorphous PbTiO3 buffer layers are effective in forming PZT thin films with fine dense grains. The sputtered PZT thin films with Ti-rich phase showed excellent ferroelectric properties. The polarization retention properties of PZT capacitors with Ti-rich phase are remarkable, and the value of the retained polarization density after 10 years is expected to be larger than 40 μC/cm2. Further, 150-nm-thick PZT capacitors with Zr/Ti=30/70 showed 2P, at 1.5 V of more than 30 μC/cm2, and good retention property. These results indicate the potential of the lower voltage operation of sputtered PZT capacitors by optimizing the film composition and thickness.
Temperature Dependence of the Reversible and Irreversible Polarization Contributions in Ferroelectric Thin Films
Authors: Bolten D. , Böttger U. , Grossmann M. , Lohse O. , Waser R. , Kastnert M. , Schindlert G. , Dehmo C. 
Published: April 2011

AbstractIn this paper the temperature dependence of reversible and irreversible polarization contributions in the temperature range between 223 K and 473 K is investigated to elucidate the microscopic mechanism responsible for reversible and irreversible changes of the ferroelectric polarization. Small signal capacitance measurements under dc-bias are used to measure the reversible contributions. Quasi-static hysteresis measurements are used to obtain the total polarization, i.e. the sum of the reversible and irreversible contributions. The combination of both measurements allows the separation of the reversible and irreversible parts. The reversible and irreversible contributions are demonstrated for SrBi2Ta2O9 (SBT), SrBi2Ta2-xNbxO9 (SBTN) thin films and compared to tetragonal PbZr0.3Ti0.7O3 (PZT) thin film capacitors.
Structural and Electrical Characterization of Rare Earth Doped Pb0.85La0.15TiO3 Ferroelectric Thin Films
Authors: Dobal P. S. , Das R. R. , Roy B. , Katiyar R. S. , Jain S. , Agrawal D. C. 
Published: April 2011

AbstractRare earth (Gd+3 and Ce+3) substitution on La+3 sites of the sol-gel prepared Pb0.85La0.15TiO3 films is studied using x-ray diffraction, atomic force microscopy, Raman scattering, and electrical characterization techniques. With increasing content of rare earths an increase in the lattice tetragonality was evidenced from x-ray data. Raman spectra obtained form Pb0.85La0.15-xCexTiO3 (x=0.0–0.07) and Pb0.85La0.15-xGdxTiO3 (x=0.0–0.15) films show features characteristics of PbTiO3 perovskite. Frequency variations of the lowest soft mode as a function of the composition x and temperature corraborate the increased tetragonality in these films. The ferroelectric transition temperature, dielectric constant, and coercive field was found to increase with Gd content. The phase transition temperature and polarization values increase up to 5 at.% Ce doping while they decrease above that composition due to the reduced domain wall mobility caused by Ce precipitation. A slight increase in the surface roughness was observed with increasing rare earth content in these films.
Depth Profiling of Solution-Deposited Lead Zirconate Titanate Thin Films by Radio Frequency Glow Discharge Atomic Emission Spectroscopy (RF-GDAES)
Authors: Brinkman K. S , Schwartz R. W. , Marcus R. K , Anfone A. 
Published: April 2011

AbstractCompositional depth profiles have been obtained on chemical solution deposited lead zirconate titanate (PZT) thin films using radio-frequency glow discharge atomic emission spectroscopy. The technique is very rapid, requiring less than one minute for complete multi-element depth profiling of films and multilayer substrates. In the present study, the method was employed to obtain compositional profiles of the various metallic (Pb, Zr, Ti, Si) and organic-related (C, H, O) species that are present in the films and underlying device. Preliminary results using this relatively new technique are reported for PZT films deposited by an aqueous acetate process and heat treated at temperatures ranging from 300 and 700°C. The initial results from these investigations suggest that Pb volatilization occurs at temperatures as low as those typically encountered during the pyrolysis step. Significant interdiffusion of the Pb into the underlying Pt electrode at this temperature is also suggested. Effects of modifying ligand on film thickness and organic decomposition behavior were also observed.
Effects of In-Situ DC-Bias on the Composition, Microstructures and Dielectric Properties of RF Magnetron Reactive Sputtered (Ba,Sr)TiO3 Films
Authors: Chan Wen-Hao , Shen Hui-Ling , Chou Lih-Hsin , Wang Jinn-Lung , Tsai Jyi-Ching 
Published: April 2011

AbstractThin films of (Ba,Sr)TiO3 (BST) have been prepared by rf magnetron reactive sputtering using single alloy target, and in-situ negative DC-bias. Post annealing was applied to the asdeposited films at 620°C for 2 hours in 1 atm oxygen atmosphere. Thin film microstructures
and grain sizes were studied and calculated by means of X-ray diffraction, while the film composition was analyzed by Electron Probe X-ray Microanalyzer (EPMA). The dielectric constant of the films was also studied. As the applied DC-bias increased, the dielectric constant increased from 176 to 912, the x-ray diffraction patterns became more intense and narrower, and the (Ba+Sr)/Ti molar ratio increased from 0.70 to 0.83. In-situ DC-bias was observed to be a feasible fabrication process to increase the grain size and relative permittivity of sputtered BST films.
Gate Stacks for Low Voltage Ferroelectric Field Effect Devices Based on Pt/SBT/CeO2/Si(100)
Authors: Haneder T. , Hönlein W. , Bachhofer H. , Ullmann M. , von Philipsborn H. , Waser R. 
Published: April 2011

AbstractMETS (Metal Ferroelectric Insulator Semiconductor) capacitors were fabricated using CSD (Chemical Solution Deposition). Thin layers of CeO2 were deposited as an insulating buffer layer on Si(100) substrates and SrBi2Ta2O9 (SBT) was used as a ferroelectric layer. Pt electrodes were deposited by evaporation on top of the SBT layer. At constant SBT thickness the thickness of the CeO2 layer was varied to investigate the effects of the change in capacitance ratio between the ferroelectric and the buffer layer. XRD spectra were used to determine the phase of the SBT and the quality of the CeO2 layer. C(V) measurements showed the ferroelectric nature of the SBT. Additional information was provided by TEM and EDX analysis.Some samples showed a memory window as big as 1.6 Volt at a moderate voltage sweep from −3.5 to +3.5 Volt. Interface state density is approximately 2×1011/cm2 eV and remanent polarization was found to be in the range of 0.3 μC/cm2. These results are already very promising in terms of fabricating a Ferroelectric FET. Some basic considerations with respect to the development of IT memory cells on the basis of this kind of transistor will also be presented.
Effect of Y-Doping on the Dielectric Properties of BatiO3 Films Deposited in Reducing Atmospheres Using Pulsed Laser Deposition
Authors: Choi Won-Youl , Tsur Yoed , Randall Clive A. , Trolier-McKinstry Susan 
Published: April 2011

AbstractBaTiO3-based multilayer capacitors with Ni electrodes are fired at low Po2 to prevent the oxidation of Ni. Amphoteric dopants such as Y, Ho and Dy are used to prevent electrical degradation due to oxygen vacancy migration. This paper describes use of this approach in preparing thin film BaTiO3 capacitors. Tolerance of reducing atmospheres is particularly important in films which are co-processed with resistors such as TaN for integrated resistor-capacitor networks. To assess this approach, films with and without Y-doping were grown in pure N2 atmospheres by pulsed laser deposition from undoped and 0.2wt% Y2O3 doped BaTiO3 targets, respectively. Films were deposited onto Pt/Ti/SiO2/Si substrates using a 5∼10Hz laser repetition rate, an energy density of 4.2J/cm2 and a working pressure of 100mTorr. It was found that polycrystalline perovskite films could be grown at 700°C and that Y-doped films had better crystallinity than the undoped ones. The dielectric constants of films without and with Y-doping are ∼1100 and ∼1300 at lkHz, respectively. The dielectric losses of Y-doped films were lower than for undoped films, possibly because the concentration of mobile charges including oxygen vacancies was decreased. Y-doped films also have a smaller coercive field (25kV/cm) and higher maximum polarization (∼20μC/cm2) than undoped films. The defect chemistry of the system is also discussed.