bluuebunny/crossref_metadata_2025 huggingface dataset:
Bipolar Electrical Conductive Transparent Oxide, CuInO2
Authors: Yanagi Hiroshi , Ueda Kazushige , Ohta Hiromichi , Hirano Masahiro , Hosono Hideo
Published: April 2011

A transparent oxide semiconductor with delafossite structure, CuInO2, was found to exhibit both p-type and n-type conduction by doping of an appropriate impurity and tuning of proper film-deposition conditions. Thin films of Ca-doped or Sn-doped CuInO2 were prepared on -Al2O3 (001) single crystal substrates by pulsed laser deposition method. The films were deposited at 723 K in O2 atmosphere of 1.0 Pa for the Ca-doped films or 1.5 Pa for the Sn-doped films. The positive sign of the Seebeck coefficient demonstrated p-type conduction in the Ca-doped films, while the Seebeck coefficient of the Sn-doped films was negative indicating n-type conductivity. The electrical conductivities of Ca-doped and Sn-doped CuInO2 thin films were 2.8×10−3 S·cm−1 and 3.8×10−3 S·cm−1, respectively, at 300 K. The optical band gap of each film was estimated to be ∼3.9 eV. Since CuInO2 exhibited bipolarity in electrical conduction, transparent p-n homojunctions based on CuInO2 were fabricated on (111) surface of yttria-stabilized zirconia single-crystal substrates. The structure of the diode was In2O3:Sn / n-CuInO2:Sn / p-CuInO2:Ca / In2O3:Sn electrode on the substrate. The contact between the n-and p-type CuInO2 semiconducting oxides was found to be rectifying. The turn-on voltage was ∼1.8 V.
Electrical Characteristics of Doped and Undoped High Dielectric Constant BCTZ Thin Films
Authors: Yi Woo-Chul , Kalkur T. S. , Philofsky Elliott , Kammerdiner Lee
Published: April 2011

Ba1−xCaxTi1-yZryO3 materials have very high dielectric constant (up to 30,000) in the bulk form. In this paper, we are presenting the electrical and structural characteristics of undoped and 0.4% Mg-doped Ba0.96Ca0.04Ti0.84Zr0.16O3 (BCTZ) thin films on Pt/Ti/SiO2/Si substrates. The BCTZ films were deposited by spin on metal-organic decomposition method and annealed at a temperature 600-900°C in oxygen environment. The annealed thin films were characterized by X-ray diffraction. The electrical characteristics of the annealed thin films were analyzed by capacitance–voltage and current–voltage measurements. The as-annealed thin films were post- annealed in nitrogen and oxygen environments and the effect of post-annealing on their electrical characteristics were also presented in conjunction with 0.4% Mg doping effect of BCTZ thin films for possible high dielectric constant material applications.
Phase Formation Kinetics in Sol-Gel Derived Strontium Bismith Tantalate
Authors: Sung Yun-Mo , Kwack Woo-Chul
Published: April 2011

Phase formation characteristics of Sr0.7Bi2.4Ta2O9 (SBT) powder, synthesized via sol-gel and pyrolysis process, was investigated by using thermal analysis. Each of the two exotherms, appearing in differential thermal analysis (DTA) scan curves, was identified as crystallization of fluorite phase and transformation of fluorite to aurivillius phase, respectively by using x-ray diffraction (XRD). By applying non-isothermal kinetic analyses to the DTA results, activation energy values for the formation of fluorite and aurivillius phases were determined as 192 and 375 kJ/mol, respectively and Avrami exponent values for each reaction were determined as 0.91 and 0.96, respectively. These activation energy and Avrami exponent values were discussed in detail to understand phase formation mechanism in SBT system.
Kinetic Analysis of PbTiO3 Phase Formation Via Diffusion Couple Method
Authors: Sung Yun-Mo , Kwack Woo-Chul
Published: April 2011

A detail kinetic analysis was performed on the PbTiO3 phase formation reaction occurring via PbO-TiO2 diffusion couple experiments. The diffusion model of Pb2+ and O2− ions was used to derive the kinetics equation of PbTiO3 phase formation reaction. From the parabolic kinetics between the thickness of PbTiO3 layer and time, the reaction rate constant for PbTiO3 formation was determined to be a function of the average diffusion coefficient of Pb2+ ions. By substituting the diffusion couple experimental results into the present kinetics equation, average diffusion coefficient values of Pb2+ ions in PbTiO3 layer were calculated according to temperature values. The activation energy value for the diffusion of Pb2+ ions was estimated for PbTiO3 formation using Arrhenius plot and the equation for the diffusion coefficient of Pb2+ ions was determined.
Microstructure and Physical Properties of Ferroelectric-gate Memory Capacitors with Various Buffer Layers
Authors: Caragianis-Broadbridge Christine , Han Jin-ping , Ma T. P. , Lehman Ann Hein , Zhu Wenjuan , Luo Zhijiong , Pechkis Daniel L. , Laube Bruce L.
Published: April 2011

This paper reports the microstructure and physical properties of ferroelectric capacitors formed from SrBi2Ta2O9(SBT) layers on Si with various buffer layers including jet-vapor deposited silicon nitride, zirconium oxide, hafnium oxide and thermally grown silicon oxide. Results from cross-sectional transmission electron microscopy (X-TEM), energy dispersive spectroscopy (EDS), X-Ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and non-contact atomic force microscopy (nc-AFM) data coupled with capacitance-voltage (C-V) and current- voltage (I-V) data indicate that both the microstructure and physical properties of SBT films deposited on silicon are dependent on the buffer layer material employed.
Abnormal Spectral Behavior of Trivalent Neodymium Ions in Potassium Yttrium Fluoride Crystals
Authors: Yang Chunlai , Bartolo Baldassare Di
Published: April 2011

Nd3+ ions in KYF4 can occupy different sites. The energy transfer processes that take place between them are responsible for the unusual behavior of Nd3+. From the spectroscopic measurements at different temperatures we found an anomalous spectroscopic behavior in the low temperature range (20K - 100K). Based on an energy transfer model, we proposed an explanation to this abnormal behavior. We derived the formula to describe the deexcitation process and make a data fitting on our dynamic decay measurements.
Influence of Pressure on 5d → 4f Emission Transitions of Ce3+
Authors: Cunningham Garry B. , Shen Yongrong , Bray Kevin L. , Mendoza Ulisses R. Rodriguez
Published: April 2011

High pressure is used to tune the emission and band structure of the phosphors Ce3+:Lu2S3 and Ce3+:Lu2SiO5. A significant red shift of the broad 5d → 4f emission of Ce3+ was observed in both phosphors. In Ce3+:Lu2S3, we also observed a significant decrease in the emission intensity of Ce3+ and attribute the quenching to a pressure-induced electronic crossover of the Lu2S3 conduction bandedge with the emitting 5d state of Ce3+. In Ce3+:Lu2SiO5, two Ce3+ sites are present and we observed energy transfer from one site (Ce(2)) to the other (Ce(1)) at low pressure. At high pressure, the energy transfer ceases and emission is no longer observed from the Ce(1) site. We propose an exciton recombination model of the energy transfer process.
Divalent and Trivalent Europium Doped Alumina Waveguides Elaborated by Pulsed Laser Deposition
Authors: Minardi Anne , Garapon Claudine , Mugnier Jacques , Champeaux Corinne
Published: April 2011

Europium doped alumina Al2O3optical waveguides were prepared by pulsed laser deposition (PLD) using a KrF laser. The targets were obtained by sintering doped powders synthesized by a sol-gel method. Depending on the oxygen pressure used during the deposition, Eu3+ (for 0.1 mbar) or Eu2+ (for 10−5 mbar) are obtained in the films. Two kinds of Eu2+ ions are present, with a 4f-5d broad excitation band peaking at 330 nm and emission bands located at 490 nm or 585 nm respectively. For Eu3+ doped films, the usual 5D0 to the 7FJ multiplets emission spectra were observed. The emission lines are strongly inhomogeneously broadened. Low temperature site selective fluorescence measurements were achieved in order to correlate the different Eu3+ sites observed with the structure of the films (amorphous or γ crystallized).
PL due to Discrete Gap Levels in Some Chalcogenide Glasses- A Configurational Coordinate Diagram Illustration
Authors: Bhat N. Asha , Sangunni K.S. , Rao K.S.R.K.
Published: April 2011

Photoluminescence (PL) studies were carried out on a-Se and a few Ge20Se80−xBix and Ge20Se70−xBixTe10 bulk glassy semiconductors at 4.2 K with Ar+ laser as excitation source. While a-Se and samples with lesser at% of Bi show fine structured PL with a large Stokes shift, samples with higher at% of Bi did not show any detectable PL. The investigations show at least three radiative recombination transitions. Features extracted by deconvoluting the experimental spectra show that the discrete gap levels associated with the inherent coordination defects are involved in the PL transitions. Absence of PL in samples with higher Bi at% are explained on the basis of nonradiative transition mechanisms. Overall PL mechanism involving gap levels in chalcogenide glasses is illustrated with the help of a configurational coordinate diagram.
Enhancement of Cathodoluminescent Characteristic from CaTiO3:Pr3+, by Ga3+ Addition
Authors: Byun Jung-Woo , Lee Byung-Kyo , Kim Dong-Kuk , Kang Seong-Gu , Kang Seung-Youl , Suh Kyung-Soo
Published: April 2011

CaTiO3:Pr3+ as an oxide phosphor is expected to be applied for a field emission display(FED) due to its relatively high conductivity. For the practical use, however, the CL intensity of CaTiO3:Pr3+ has to be enhanced. We introduced Ga3+ as a co-activator into the phosphor and investigated the CL characteristics with various Ga3+ concentrations. The CL intensity of CaTiO3:Pr3+ was remarkably increased when Ti4+ atom was replaced by the Ga3+. When the Ga3+ concentration is 5 times of Pr3+ molar concentration, the emission intensity of the CaTiO3:Pr3+ phosphor with Ga3+ is about 5 times higher than Ga3+-free samples. So, it was concluded that the addition of Ga3+ is essential to enhance CL property at low voltage. We proposed the following mechanism that excitation into the host lattice leads to the formation of electrons in the conduction band and holes in the valence band. The electrons in the conduction band recombine with the holes trapped at Ga3+ and this energy is effectively transferred to Pr3+ ion, which gives its own characteristic red emission.
Luminescence of doped nanocrystalline ZnSe
Authors: Suyver J. F. , Wuister S. F. , van der Beek T. , Kelly J. J. , Meijerink A.
Published: April 2011

Luminescence of nanocrystalline ZnSe:Mn2+ and ZnSe:Cu2+ prepared via an organic chemical synthesis method are described. The spectra show distinct ZnSe, Mn2+ and Cu2+ related emissions, all of which are excited via the host lattice. The Mn2+ emission wavelength depends on the concentration of Mn2+incorporated into the ZnSe lattice, which is attributed to the presence of Mn2+ pair-states at higher concentrations. The ZnSe:Cu2+ luminescence was studied as a function of the crystal-size. Temperature-dependent photoluminescence spectra and photoluminescence lifetime measurements are also presented and the results are compared to those of Mn2+ and Cu2+ in bulk ZnSe.
Blue Room-Temperature Photoluminescence of AlN Films, Prepared by RF Magnetron Sputtering
Authors: Ligatchev V. , Yoon S.F. , Ahn J. , Zhang Q. , Rusli  , Chew K. , Zhgoon S.
Published: April 2011

Photo luminescence (PL) signal from the aluminum nitride (AlN) films, excited by near UV (363.8 nm) laser has been measured at the room temperature. The AlN films are deposited by radio frequency (RF) sputtering of aluminum in argon-nitrogen-hydrogen gas mixture. Positions of the PL peaks maximums are influenced by the AlN preparation regimes. The analysis of the PL data is based on the results of the structural studies and electron spectrum investigations.
Structural and Optical Properties of ZnS:Mn Films Grown by Pulsed Laser Deposition
Authors: Yeung K. M. , Lu S. G. , Mak C. L. , Wong K. H.
Published: April 2011

High-quality manganese-doped zinc sulfide (ZnS:Mn) thin films have been deposited on various substrates using pulsed laser deposition (PLD). Effects of back-filled Ar pressure and substrate temperature on the structural as well as optical properties of ZnS:Mn films were studied. Structural properties of these films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Photoluminescence (PL) and optical transmittance were used to characterize the optical properties of these films. Our results reveal that ZnS:Mn films were polycrystalline with a mixed phase structure consisting of both wurtzite and zinc-blende structure. The ratio of these two structures was strongly depended on the change of substrate temperature. Low substrate temperature facilitated the formation of zinc-blende structure while the wurtzite phase became dominant at high substrate temperature. ZnS:Mn films with preferred wurtzite structure were obtained at a substrate temperature as low as 450°C. An orange-yellow emission band was observed at ∼590 nm. As the substrate temperature increased, the peak of this PL band shifted to a shorter wavelength. Furthermore, shifts in the absorption edge and the energy gap due to the change in substrate temperature were also observed. The variation in these optical properties will be correlated to their structural change.
Photoluminescence of multi-layer GeSi dots grown on Si (001)
Authors: Wan J. , Luo Y. H. , Jin G. L. , Jiang Z. M. , Liu J. L. , Liao X. Z. , Zou J. , Wang Kang L.
Published: April 2011

Temperature and power dependent photoluminescence measurements were carried out on the multi-layer structure of GeSi dots grown on Si(001) substrate by gas-source molecular beam epitaxy. The transfer of photon-induced carriers from wetting layers into the dots and the region near the dots was evidenced. Different power dependent behaviors of the photoluminescence peak position were observed for the dots and the wetting layer. Accordingly, type-II and type-I band alignments were proposed for the dots and the wetting layers, respectively. After annealing, the photoluminescence peaks from the dots and the wetting layers showed blueshift due to the atomic intermixing. For the samples annealed at temperature above 850°C for 5min, the band alignment of the dots changes from type-II to type-I.
SSRM and SCM observation of modified lateral diffusion of As, BF2 and Sb induced by nitride spacers.
Authors: Eyben P. , Duhayon N. , Stuer C. , Wolf I. De , Rooyackers R. , Clarysse T. , Vandervorst W. , Badenes G.
Published: April 2011

Initial studies (using Scanning Spreading Resistance Microscopy) on the lateral diffusion of B and As have shown an important influence of the thickness of oxy/nitride spacers. The latter phenomenon was tentatively ascribed to stress enhanced diffusion under the spacer region [1]. These studies have been complemented with Scanning Capacitance Microscopy (SCM) measurements, which confirm the SSRM-data. In fact both techniques shows a similar increase in lateral diffusion with increasing spacer thickness (∼ 0.2 nm/nm spacer thickness), whereby no effect is observed on the vertical diffusion. When using spacers with or without TEOS-liner, fairly similar enhancements could be seen. Micro-Raman and CBED stress measurements for these cases do however show a large reduction in stress when a TEOS-liner is used, suggesting that the correlation (at least to the final) stress is not really justified. A possible explanation could however be that the lateral diffusion occurs before the stress relaxation within the thermal treatment. In order to elucidate the diffusion mechanism (initial stress, interstitials, hydrogen incorporation, TED,..) we have expandedthe experimental matrix with a vacancy diffuser such as Sb and simulated the potential H-incorporation duringthe nitride deposition by a hydrogen anneal. Moreover we also have studied the impact of TED by splits with RTP-anneals before the nitride deposition.
Self-Diffusion in Intrinsic and Extrinsic Silicon Using Isotopically Pure 30Silicon Layer
Authors: Nakabayashi Yukio , Osman Hirman I. , Segawa Toru , Toyonaga Kazunari , Matsumoto Satoru , Murota Junichi , Wada Kazumi , Abe Takao
Published: April 2011

Silicon self–diffusion coefficients were measured in intrinsic and extrinsic silicon from870 to 1070°C using isotopically pure 30Si layer. 30Si diffusion profiles are determined by secondary ion mass spectrometry. The temperature dependence of intrinsic diffusion coefficient in bulk Si isobtained. Comparing it in heavily As-doped or B-doped Si, it is found that Si self-diffusion is entirely mediated by interstitialcy mechanism at lower temperatures below 870°C.
A new model for Boron diffusion retardation in SiGe-strained layers accounting for the mechanism of Boron trapping/detrapping by Ge atoms.
Authors: Kol'dyaev Victor I.
Published: April 2011

The main drawbacks of the known models of the B diffusion in strained SiGe layers are summarized. A mechanism is suggested to self-consistently explain the main experimental features and original experimental data which considers the trapping of B atoms by Ge atoms during B diffusion in the Si lattice resulting in the retarded B diffusivity. Fluctuations of Ge atom numbers in a nearest B atom environment result in percolation mechanism of B transport through dilatation centers of random size. A new solid state transport modelis generalized by considering dispersion transport of positive and negative point dilatation defects.
Phosphorus diffusion in silicon; influence of annealing conditions
Authors: Christensen J. S. , Kuznetsov A. Yu. , Radamson H. H. , Svensson B. G.
Published: April 2011

Phosphorus diffusion has been studied in both pure epitaxially grown silicon and Cz silicon, with a substantial amount of impurities like oxygen and carbon. Anneals have been performed in different atmospheres, N2 and dry O2, as well as in vacuum, at temperatures between 810 – 1100°C. Diffusion coefficients extracted from these anneals show no difference for the P diffusion in the epitaxially grown or the Cz silicon. The diffusion coefficients follow an Arrhenius dependence with the activation energy Ea=2.74±0.07 eV and a prefactor D0 = (8±5)×10−4 cm2/s. These parameters differ considerably from the previously reported and widely accepted values (3.66 eV and 3.84 cm2/s, respectively). However, vacuum anneals of the same samplesresult in values close to this 3.6 eV diffusion mode. Furthermore, control anneals of boron doped samples, with similar design as the phosphorus samples, suggest the same trend for boron diffusion in silicon – lower versus higher values of activation energies for nitrogen and vacuum anneals, respectively. These results are discussed in terms of the concentration of Si self-interstitials mediating the diffusion of phosphorus and boron.
Modeling Threading Dislocation Loop Nucleation and Evolution in MeV Boron Implanted Silicon
Authors: Avci Ibrahim , Law Mark E. , Jasper Craig , Rueda Hernan A. , Thoma Rainer
Published: April 2011

A single statistical point defect based model for the nucleation and evolution of dislocation loops during annealing in Si is developed. The model assumes that the radius and the density of dislocation loops follow a log normal distribution. The loop nucleation part of the model also assumes that all the loops come from {311} unfaulting. The model is verified with the experimental results obtained by studying the formation of dislocation loops and threading dislocation loops as a function of implant condition in boron implanted silicon by varying the dose from 1×1013 to 5×1014 cm−2 at an energy of 1.5 MeV. Due to the statistical nature of the model, the threading dislocation loop density is easily obtained from simulation results. The dramatic change in the threading dislocation loop density withthe increasing implant dose is also predicted by the simulations.
Diffusion and Defect Structure in Nitrogen Implanted Silicon
Authors: Dokumaci Omer , Kaplan Richard , Khare Mukesh , Ronsheim Paul , Burnham Jay , Domenicucci Anthony , Li Jinghong , Fleming Robert , Adam Lahir S. , Law Mark E.
Published: April 2011

Nitrogen diffusion and defect structure were investigated after medium to high dose nitrogen implantation and anneal. 11 keV N2+ was implanted into silicon at doses ranging from 2×1014 to 2×1015 cm−2. The samples were annealed with an RTA system from 750°C to 900°C in a nitrogen atmosphere or at 1000°C in an oxidizing ambient. Nitrogen profiles were obtained by SIMS, and cross-section TEM was done on selected samples. TOF-SIMS was carried out in the oxidized samples. For lower doses, most of the nitrogen diffuses out of silicon into the silicon/oxide interface as expected. For the highest dose, a significant portion of the nitrogen still remains in silicon even after the highest thermal budget. This is attributed to the finite capacity of the silicon/oxide interface to trap nitrogen. When the interface gets saturated by nitrogen atoms, nitrogen in silicon can not escape into the interface. Implant doses above 7×1014 create continuous amorphous layers from the surface. For the 2×1015 case, there is residual amorphous silicon at the surface even after a 750°C 2 min anneal. After the 900°C 2 min anneal, the silicon fully recrystallizes leaving behind stacking faults at the surface and residual end of range damage.
Modeling Boron and Indium Electrical Activities in Silicon in the Presence of Nitrogen
Authors: Zubkov Vladimir , Aronowitz Sheldon , Puchner Helmut , Senosiain Juan P.
Published: April 2011

The ab initio pseudopotential code (VASP) was employed to explore indium and boron electrical activities in silicon in the presence of nitrogen. Electrical activities for the combinations B+N, In+N, and In+B+N were explored. Formation energy of a negatively charged supercell, (E−)f, and a band gap, Eg, from calculations with one k point were chosen as indicators of acceptor activity. For separate dopants the calculated (E−)f and Eg values indicate that substitutional B and In are effective acceptors and N is an extremely weak donor. When nitrogen is adjacent to, or separated 3 - 5 bonds from B or In, it suppresses acceptor activity. Binding is greater for In+N than for B+N in agreement with secondary ion mass spectroscopy (SIMS) data that demonstrates a greater retention of N by In. This should lead to a greater drop in activity for In+N combination versus B+N one, in agreement with spreading resistance profiling (SRP) experiments. Loss of activity in In+B+N combination might be due to long range interactions between dopants.
Laser Thermal Induced Crystallization for 20 nm Device Structures
Authors: Yang Shenzhi , Thompson Michael O.
Published: April 2011

The melt kinetics of shallow junction formation by laser thermal processes has been studied using transient conductance measurements. The melt and solidification dynamics of 20 nm amorphous layers were measured and shown to follow behaviors predicated by deeper melts, including explosive crystallization and interface bounce back. The effects of surface barrier oxides and metal absorber layers, required for CMOS process integration, were examined and shown to be nearly negligible. Quantitative evaluation of a device process window by these measurements was in good agreement with sheet resistance results. Finally, the effect of the buried oxide in SOI structures was investigated. Solidification velocities in such structures were reduced by a factor of three as compared with bulk silicon.
Why abrasive free Cu slurry is promising?
Authors: Kamigata Yasuo , Kurata Yasushi , Masuda Katsuyuki , Amanokura Jin , Yoshida Masato , Hanazono Masanobu
Published: April 2011

To develop high signal speed semiconductor LSIs, Cu interconnection is one of the most important requirements. In the fabrication of Cu interconnections using CMP method, minimized dishing, erosion and reduction in micro-scratches are large issues to be realized. We performed a research for superior properties of Cu CMP. Finally, we succeeded in developing Abrasive Free (AF) Cu slurry suitable for these requirements.

We also developed slurry for barrier (TaN) with a high selectivity between TaN and SiO2 of 50 to reduce oxide (SiO2) loss. This reduced oxide loss is directly related to obtaining a controlled circuit resistivity.

By applying these two kinds of slurries, ULSIs with multilevel Cu interconnects and excellent reliabilities were obtained.
Polyurethane Pad Degradation and Wear Due to Tungsten and Oxide CMP
Authors: Moy Amy L. , Cecchi Joseph L. , Hetherington Dale L. , Stein David J.
Published: April 2011

Polyurethane polishing pads are commonly used for chemical-mechanical polishing (CMP) of semiconductor wafers. Structural, chemical, and mechanical property changes of the polishing pads due to CMP are examined. Tungsten and oxide film layers are polished from the wafer surface using the polishing pad and abrasive slurry system. The polishing pad surface is flattened with polishing, and hence, reducing the effective area for slurry transport. The abrasive is used for abrading off the film from the surface. W, Al, I, and K accumulate in the polishing pad after tungsten CMP and Si accumulates after oxide CMP. Material accumulates in the pad pores and grooves. Electron Microprobe X-ray Analysis and Wavelength Dispersive Spectrometry (WDS) were used to examine the changes across the thickness of the pad. Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the changes to the polyurethane isocyanate group. The reduction in the isocyanate group and increase in the hydroxyl group after tungsten CMP indicates that a hydrolysis reaction of the isocyanate to form carboxylic acid occurs.
High-performance CMP Slurry with Inorganic/Resin Abrasive for Al/Low k Damascene
Authors: Yano Hiroyuki , Matsui Yukiteru , Minamihaba Gaku , Kawahashi Nobuo , Hattori Masayuki
Published: April 2011

CMP slurry with inorganic/resin abrasive was investigated for the Al/low k damascene wiring. [1] The slurry showed less scratching, higher polishing rate and better planarity. These advantages are attributable to the elasticity of the resin. The soft resin particle behaves as a cushion and prevents the scratching caused by agglomerated inorganic particles and foreign material. The springy feature of the resin particle increases the selectivity of removal rate at convex portions and concave portions. Furthermore, the pressure is loaded to the Al film surface effectively through the resin particle and higher CMP rate can be achieved even without chemicals such as oxidizers and acids. [2] This chemical free polishing would be the advantageous for preventing the corrosion of Al.
Modeling of Feature-Scale Planarization in STI CMP Using MESATM
Authors: Laursen Thomas , Kim Inki , Schlueter James
Published: April 2011

MESA is a feature-scale planarization model that predicts the changing topography of the wafer surface during the chemical mechanical polishing (CMP) process used in IC manufacturing. This model has previously been applied to the polish of inter-level dielectrics and copper. The present study is part of a model validation procedure for shallow trench isolation (STI) using experimental feature-scale data. It was carried out using the SpeedFam-IPEC Auriga polisher with SKW Associates 200-mm wafers (SKW3 MIT-STI-mask), Rodel IC 1000/1400 pads and Cabot SS-12 slurry. MESA accounts for observed differences in planarization using Rodel IC1000 with and without foam backing as well as the pattern-density dependence within each die. The data were obtained and plotted in such a way that the active-area and trench-oxide levels are displayed throughout the whole polish, including the points where active area clears to nitride and silicon as well as where trench oxide dishes below the silicon level. The pattern density effect is evident in both cases, but a comparison between the two pads shows less pattern density effect and improved planarization with the single IC 1000 pad.

MESA is shown to predict the details of the topographical evolution for STI CMP on the feature scale. When validated by fitting the pad constants k1 and k2 to describe the planarization, MESA provides reasonably accurate predictions for the polish of any oxide pattern structure as long as the same CMP process is used.
Direct Visualization of Particle Dynamics in Model CMP Geometries
Authors: Zettner Claudia M. , Yoda Minami
Published: April 2011

Chemical-mechanical polishing (CMP) involves complex mechanical and chemical interactions between a rough elastomeric pad, the wafer being polished and an abrasive slurry containing sub-micron diameter silica particles. The interaction between these abrasive particles and the wafer surface and their impact upon material removal rates is still unclear. Particle dynamics in a model CMP geometry are studied experimentally in this work. Only the particles that actually interact with, and presumably polish, the model wafer surface are visualized using total internal reflection fluorescence (TIRF). The effect of process properties such as particle diameter, particle material, pad-wafer separation and shear rate upon the particle concentration immediately adjacent to the wafer surface is investigated.
Multiprobe End-Point Detection for Precision Control of the Copper CMP Process
Authors: Laursen Thomas , Grief Malcolm
Published: April 2011

Sentinelä is an optical multiprobe endpoint detection (EPD) system that has been developed by SpeedFam-IPEC (SFI) for the 200-mm and 300-mm Momentum orbital polishers. Sentinel EPD for copper CMP is based on monitoring the visible spectrum of light from a Xenon (Xe) flash lamp, which has been reflected by the wafer surface during polish. Large representative areas of the wafer are monitored from multiple locations in the pad continuously throughout the polish process. Spectra of reflected light from cleared and uncleared copper on a pattern wafer demonstrate a clear transition from copper to the underlying dielectric layer.

With the Sentinel EPD system, the wafer is probed at optimized multiple locations constantly throughout the polish process by small-diameter light spots. The coverage of the monitoring is extensive and the radial coverage is substantial on a real-time basis. The EPD call is made based on an EPD signal, which displays the fractional copper coverage as a function of polish time. The detection of copper clearing on the SFI Momentum tools is very reliable and predictable, and not sensitive to process changes.
Comparison Study for TiN Films Deposited from Different Method: Chemical Vapor Deposition and Atomic Layer Deposition
Authors: Kim Byoung-Youp , Lee Seung-Hyun , Park Sang-Gee , Oh Ki-Young , Song Juho , Kim Do-Heyoung
Published: April 2011

This paper compared two different film deposition processes for formation of TiN barrier layers, conventional TiCl4-based chemical vapor deposition and atomic layer deposition (ALD). The 30nm thick TiN film deposited by conventional TiCl4-based CVD at the process temperature of 600°C followed by NH3 post-deposition anneal showed about 180 μΩcm of resistivity, over 95 % of step coverage for the pattern aspect ratio of 6 on 0.35 μm contact diameters, and below 2 at.% of chlorine contents in the film. Meanwhile, the films deposited by ALD at 100°C lower process temperature than CVD showed much better film properties even without post-deposition anneal. It showed lower resistivity values and lower chlorine incorporation along with better step coverage characteristics. More detailed material analysis was done by AFM, SEM, and AES.
Electrochemical Properties of SnO2 Thin Films Doped with Bi and Si for Negative Electrode of Microbattery
Authors: Kim Young-Il , Moon Hee-Soo , Ji Kwang-Sun , Lee You-Kee , Park Jong-Wan
Published: April 2011

Tin oxide has been proposed as a promising alternative anode material for microbatteries. It has been reported that its theoretical volumetric capacity is four times larger than that of carbon-based materials, while its gravimetric capacity is twice as large. In this experiment, optimal Si and Bi doped SnO2 films were prepared with e-beam evaporation to improve both the cycle performance and the reversible capacity. The films with addition of Si only exhibited reductions in aggregation of tin particles and formation of micro-cracks. However, there still remained cracks, which induce capacity loss during cycling. To improve capacity retention, Bi was added with Si to SnO2 films, which exhibited the highest reversible capacity of 200µAh/cm2-µm at 200th cycle. The films doped with Bi and Si were found to be ill-defined and featureless without noticeable particle aggregation and cracks. However, the films that underwent cycling tests showed again aggregated tin particles and formation of cracks, which would induce cell failure during cycling. We believe that some types of Li-Bi phases as mixed-conductor matrices have improved the cycle life.
Processing of yttria stabilized zirconia thin films by liquid fuel combustion chemical vapor deposition
Authors: Xu Zhigang , Wei Q. , Sankar Jag
Published: April 2011

Yttria fully stabilized zirconia (YSZ) thin films have been successfully synthesized with atmospheric combustion chemical vapor deposition (ACCVD) technique with liquid fuel. Key processing parameters, such as the ratio of oxygen to liquid fuel in the flame, the concentration of metal reagents in the solution, the temperature of the substrate and substrate material, have been investigated. The as-grown films are characterized with X-ray diffraction and scanning electron microscopy. Within the range of experimental parameters, the phase of the film is predominantly of cubic structure. The phase and crystallinity of the films are strongly dependent upon the experimental variables.
Material and Electrical Characterization of Carbon-Doped Ta2O5 Films for Embedded DRAM Applications
Authors: Chu Karen , Cho Byeong-Ok , Chang Jane P. , Steigerwald Mike L. , Fleming Robert M. , Opila Robert L. , Lang Dave V. , Dover R. Bruce Van , Jones Chris D.W.
Published: April 2011

We studied the effect of carbon incorporation on the material and electrical properties of Ta2O5 thin film. We doped the Ta2O5 films with carbon using pulsed-dc reactive and rfmagnetron sputtering of Ta2O5 performed in an Ar/O2/CO2 plasma. In thick (70 nm) films, an optimal amount (0.8 - 1.4 at.%) of carbon doping reduced the leakage current to 10−8 A/cm2 at +3 MV/cm, a four orders of magnitude reduction compared to that in a pure Ta2O5 film grown in similar conditions without CO2 in the plasma. This finding suggests that carbon doping can significantly improve the dielectric leakage property at an optimal concentration. X-ray Photoemission Spectroscopy (XPS) analysis showed the presence of carbonate in these electrically improved carbon-doped films. Analysis by high-resolution transmission electron microscopy (HRTEM) exhibited no morphological or structural changes in these carbon doped films. Carbon doping showed no improvement in the leakage current in thin (10 nm) Ta2O5 films. This phenomenon is explained by a defect compensation mechanism, in which the carbon-related defects remove carriers at low concentrations but form a hopping conduction path at high concentrations.
Role of Si(100) Surface Patterns in the Phase Separation of Cu/Sn Thin Films
Authors: Hu Qin , Zinke–Allmang Martin , Mitchell Ian V.
Published: April 2011

We report on the competitive phase separation of copper and tin thin film deposits on a pre–patterned Si(100) surface. The initial pattern on Si(100) was achieved through a thermal decomposition process of an ex–situ grown oxide film. Copper and tin phase separation on silicon is a competitive process with Cu forming preferrably silicide. Sn is observed to cover the silicide clusters when present in a sufficient amount. The pre–patterning of the surface introduces a new length scale in the problem. Our data suggest that this length scale plays a role while the clustering (ripening) length scale is of the same order, i.e., during nucleation and the early phase separation, but that both length scales become independent once the length scale of ripening significantly exceeds the length scale of the surface pattern.
The Influence of Plasma Composition on the Properties of Plasma Treated Biomaterials
Authors: Cruz Nilson C. , Rangel Elidiane C. , Gadioli Giovana Z. , Mota Rogério P. , Honda Roberto Y. , Algatti Mauricio A. , Schreiner Wido H.
Published: April 2011

The response of a biological environment when in contact with an artificial material is primarily determined by the material surface properties such as composition, contact angle and free surface energy [1,2]. Owing to that, different treatments have been employed to improve the performance of biocompatible materials. In this sense, plasma-based techniques are very attractive because they enable the surface processing of materials with virtually any geometry preserving bulk properties. Furthermore, other characteristics make plasma treatment of particular interest in biomaterial processing. Those characteristics include, for instance, a) the possibility of using a large number of different chemicals to introduce any desired functional group on the surface, b) the treatment is performed in an intrinsically sterile environment and, c) different kind of materials (such as ceramics, metals and polymers) including those chemically inert can be treated.
Synthesis and Properties of Al-Based Amorphous and Microcrystalline Thin Films
Authors: Ettl Christoph , Berger Lothar , Mrosk Joachim W. , Fecht Hans-Jörg
Published: April 2011

Amorphous metal alloys are ideally suited for interconnects in micro-electromechanical sys- tems (MEMS) because of their resistance against stress- and electromigration, and their stability in chemically aggressive environments, which should both lead to a substantial improvement of lifetime and reliability of robust sensors. While amorphous refractory metal alloys and amor- phous silicides are excellent interconnect materials for devices operating at elevated tempera- tures, these systems lack the cost-effective and easy interconnect processing of the prevalent polycrystalline aluminum alloy metallizations. Amorphous aluminum alloys are applicable to devices operating at up to 200°C, and their stressmigration resistance and chemical stability is far superior to conventional polycrystalline aluminum alloys. These new metallizations are very promising for processing interconnects, in particular because of their high strength and ductility, though having low density, and their relatively low electrical resistivity compared to other amor- phous metal alloys. Therefore these metallizations are especially suited for surface acoustic wave (SAW) sensors, where the interconnects are exposed to considerable mechanical strains. In this work amorphous Aluminum Yttrium alloy thin film metallizations deposited on appropriate sub- strates at room temperature (R.T.) by ultra-high vacuum (UHV) electron beam evaporation will be presented, and their mechanical and electronic properties together with their temperature sta- bility will be investigated.
Zinc Oxide/Copper Oxide Mixed Films Deposited by CVD
Authors: Chang Yuneng , Yeh Chihhsiang
Published: April 2011

Metal organic chemical vapor deposition (MOCVD) was used to prepare ZnO/Cu2O mixed films. The process condition studied were: deposition temperature from 360oC to 440oC, partial pressures of oxygen, 190-380 torr, precursor copper acetylacetonate (Cu(acac)2), 0.21 torr, and zinc acetylacetonate(Zn(acac)2), 0.45 torr. AES and XPS analysis showed average elemental content being Cu, 52-66%, Zn, 11-20%, O, 30-40%. Copper presented primarily as Cu(I) ions, and Zn as Zn(II) ions. SEM, SAM and XRD indicated that deposited films were polycrystalline with composite structure. Some films had a continuous ZnO thin layer with flat surface, equiax fine grained. On the top of ZnO layer were covered by discrete, irregular shape, coarse Cu2O grains. Primary Cu2O phases were (110), (111), and (200) orientation. ZnO phases were (002), and (103). SEM showed the impact of deposition temperature on Cu2O grain size. Such data were used to estimate the activation energy for grain growth. In fact, to our experiences from these studies, binary metal oxide CVD showed a wide spectrum of film microstructure and morphology. These phenomena reflect the result caused by both thermodynamics as film composition, and kinetics as mass transfer/ surface reaction rate.
Improvement of crystallographic characteristics of CoCrTa thin film using double underlayer
Authors: Kim Y.J. , Kong S.H. , Nakagawa S. , Naoe M. , Kim K.H.
Published: April 2011

High c-axis oriented CoCr-based thin films are expected for ultra-high density recording media in perpendicular magnetic recording system. In order to improve dispersion angle of c-axis of CoCr-based for perpendicular magnetic recording media, we prepared trilayered film with double underlayer using New Facing Targets Sputtering apparatus. The thickness of magnetic layer CoCrTa and double underlayer, such as interlayer Pt, paramagnetic CoCr, underlayer Ti was fixed 50nm and 20nm respectively. In order to prepare the thin film, we fixed argon gas pressure 1mTorr, substrate temperature 250°C and input current 0.5A. The crystallographic characteristics of CoCrTa layer with varying interlayer thickness (0- 20nm) have been investigated. By the result, the CoCrTa trilayered thin film with interlayer Pt showed good c-axis orientation 3.45° and 3.62° at thickness 5nm and 10nm respectively. However, CoCrTa thin film using interlayer paramagnetic CoCr showed 8.28° and 8.62° at thickness 5nm and 10nm respectively.
In-Situ Characterization Of Ultra-Small Magnetic Junctions Made By Electrochemical Techniques
Authors: Sokolov A. , Jennings J.R. , Yang C-S , Redepenning J. , Doudin B.
Published: April 2011

Electrochemical impedance spectroscopy is used to characterize the growth of NiO over Ni electrodes. We find a limited increase of thickness and a significant increase of porosity of the oxide as a function of time and anodization potential. Conductance measurements performed on Ni/NiO/Co junctions of 30 nm diameters indicate the presence of a Coulomb blockade at low temperatures and small bias. Tunneling is observed at higher bias. Small magnetoresistance ratios (1%) are found.
Studies on Crystal Structure and Magnetic Scaling Behavior of Perovskite-Like (La1−xPbx)MnO3 System with x = 0 - 0.5
Authors: Huang Ting-Sheng , Chen Chiung-Hsiung , Tai Ming-Fong
Published: April 2011

The magnetic critical behaviors in the perovskite-like (La1−xPbx)MnO3 series with x = 0.0 ∼ 0.5 are studied by means of dc magnetic measurements. All the samples crystallize in the rhombohedral unit cell with a C R 3 space group (a 0.54 nm and c 1.33 nm). The detailed crystallographic parameters of all the samples are obtained by the refinements of the powder x-ray diffraction data using the Rietveld method. The substitution effect of Pb2+ ions on La3+ sites induces a mixed-valence state of Mn3+/Mn4+ and enhances magnetic transition temperature in the (La1−xPbx)MnO3 system. The transition temperature TC increases with the Pb content from 225 K as x = 0 to 355 K as x = 0.5. The canonical spin-glass behaviors in low fields and the scaling behaviors of magnetic physical quantities are clearly observed in all our samples. The values of the related critical exponents and the scaling functions of magnetic data are close to those of the conventional spin glass systems.
Magnetization reversal and magnetic anisotropy of Fe, Ni and Co nanowires in nanoporous alumina membranes
Authors: Kröll M. , Jongh L. J. de , Luis F. , Paulus P. , Schmid G.
Published: April 2011

The magnetization reversal and magnetic anisotropy of Fe, Ni and Co nanowires is studied at low temperatures. All nanowires show a strong shape anisotropy with the easy axis being parallel to the long axis of the wires. Co nanowires additionally show a temperature dependent magnetocrystalline anisotropy along the hexagonal c-axis, which is directed nearly perpendicular to the long axis of the wires, as is confirmed by X-Ray diffraction measurements [1] and reported by Strijkers et al. who performed NMR measurements on samples prepared in a similar way [2]. Therefore, at low temperatures and for large wire diameters a competition between magnetocrystalline and shape anisotropies can be observed. Co wires with a small diameter, however, do not show a significant magnetocrystalline anisotropy. Fcc-Co, which is only known as a high-temperature Co modification and which does not have a large magnetocrystalline anisotropy constant, becomes the predominant Co modification here [1,3]. Investigations on the size dependence of the switching field for Fe and Ni nanowires provide information about the magnetization reversal process, which takes place via a nucleation of small magnetic domains probably at the end of the wires, and subsequent propagation of the domain wall along the wire.
The Role of Disorder in the Magnetic Properties of Mechanically Milled Nanostructured Alloys
Authors: Leslie-Pelecky Diandra L. , Kirkpatrick Elaine M. , Pekarek Tom , Schalek Richard L. , Shand Paul , Williams Deborah S. , Yue Lanping
Published: April 2011

Mechanical milling provides a unique means of studying the influence of grain size and disorder on the magnetic properties of nanostructured alloys. This paper compares the role of milling in the nanostructure evolution of two ferromagnets – SmCo5 and GdAl2 – and the subsequent impact of nanostructure on magnetic properties and phase transitions. The ferromagnetic properties of SmCo5 are enhanced by short (< 2 hours) milling times, producing up to an eight-fold increase in coercivity and high remanence ratios. The coercivity increase is attributed to defect formation and strain. Additional milling increases the disorder and produces a mix of ferromagnetic and antiferromagnetic interactions that form a magnetically glassy phase. GdAl2, which changes from ferromagnetic in its crystalline form to spin-glass-like in its amorphous form, is a model system for studying the dependence of magnetically glassy behavior on grain size and disorder. Nanostructured GdAl2 with a mean grain size of 8 nm shows a combination of ferromagnetic and magnetically glassy behavior, in contrast to previous studies of nanostructured GdAl2 with a grain size of 20 nm that show only spin-glass-like behavior.
Nanocomposite with Non-Spherical Granules – Logarithmic Field Dependence of Giant Magnetoresistance
Authors: Meilikhov E. , Raquet B.
Published: April 2011

Magnetoresistance of the nanocomposite Fex(SiO2)1−x (x≍0.6) at high enough magnetic field is logarithmic function of the magnetic field. Such a dependence does not fall into the known theory of giant magnetoresistance of ferromagnetic nanocomposites. This paper examines the giant magnetoresistance of such a system in terms of a simple model where the non-ordinary quasi-logarithmic magnetic field dependence of nanocomposite magnetoresistance is related to the non-spherical granules' distribution over their shapes.
Tailoring of Magnetic Properties of Glass coated Microwires
Authors: Zhukov A.P. , González J. , Zhukova V. , Blanco J.M.
Published: April 2011

The magnetic behaviour of the glass-covered metallic microwires with a wide compositional range of composition with soft and hard magnetic character is presented. The effect of conventional furnace and dc current annealing under dc axial magnetic field or without it as well as of a chemical etching on the magnetic properties of Co and Fe-based glass coated microwires has been studied. Such treatments modify the magnetic parameters. In particular, annealing under applied magnetic field (field annealing) can improve significantly such magnetic parameters as permeability. Such phenomenology can be interpreted considering the noticeable magnetic anisotropy induced by the combined effects of the magnetic field and strong internal stresses arising from the coating. Giant magnetoimpedance (GMI) effect was observed in nearly-zero magnetostrictive amorphous microwires. Upon careful heat treatment, FeCuNbSiB amorphous microwires devitrificate into nanocrystalline structure with large variety of magnetic parameters. Hard magnetic materials with coercivity up to 800 Oe were obtained as a result of decomposition of metastable phases in Co-Ni-Cu microwires as well as after crystallization process of FeCuNbSiB amorphous microwires.