bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low-Temperature Growth of NiMnSb Heusler Alloy Thin Films
Authors: Childress J.R. , Caballero J.A. , Geerts W.J. , Petroff F. , Galtier P. , Suzuki Y. , Thiele J.-U. , Weller D. 
Published: April 2011

ABSTRACTFerromagnetic Heusler alloys such as NiMnSb may have unique applications to magnetoresistive devices because of their predicted half-metallic band-structure (i.e., 100% spin-polarized at the Fermi level). However, the high temperatures (>500°C) used to date for the synthesis of the ordered alloy in bulk or thin-film form is incompatible with the reliable fabrication of nanoscale multilayer structures from this material. We report on the growth of high-quality polycrystalline thin films, 200–1000Å thick, of Clb-structured NiMnSb by RF-magnetron sputtering of a composite NiMnSb target onto glass and silicon substrates at temperatures as low as 250°C. We have established that substrate temperature, deposition rate and argon gas pressures all play a critical role in obtaining the Clb-structured phase by direct deposition. Optimal conditions result in films whose properties, including lattice parameter, saturation magnetization, resistivity and magneto-optical Kerr rotation spectrum are identical to those of bulk NiMnSb. Additionally, coercive fields as low as a few oersteds make these films compatible with low-field applications.
Structural and Magnetic Study of Fe Stripes and Boxes Patterned by the <Atomic Saw> Method
Authors: Ressier L. , Jaffres H. , Schuhl A. , Nguyen Van Dau F. , Goiran M. , Redoules J.P. , Peyrade J.P. , Fert A.R. 
Published: April 2011

ABSTRACTThe <Atomic Saw> method has been successfully used to cut a Fe thin film, epitaxially grown onto a (001) MgO substrate, into stripes (widths ranging from 1 μm to 100 nm) and boxes (lateral sizes ranging from 1 μm to 3 μm). A structural analysis of these magnetic structures by atomic force microscopy has shown that their geometries are controlled by the plastic strain. A magnetooptical study of the Fe stripes has revealed a surprising uniaxial magnetic anisotropy with an in-plane easy axis perpendicular to the stripes. This strong anisotropy can be explained by an anisotropie relaxation of the misfit between the starting Fe film and the MgO substrate, induced by the cutting into stripes. Magnetooptical experiments on boxes have revealed that the initial cubic symmetry is recovered since, in this case, the relaxation is similar in perpendicular directions. They have also proved that their magnetization reversal is governed by nucleation phenomena.
Magneto-Optical Properties of Ni-MgO and Co-MgO Nanocomposite Films Obtained by Partial Reduction Reactions
Authors: Smith J. A. , Limthongkul P. , Hartsuyker L. , Kim S. Y. , Sass S. L. 
Published: April 2011

ABSTRACTA new processing technique was developed to synthesize metal-ceramic films containing nano-sized Ni or Co particles embedded in a MgO matrix. Sol-gel solutions were spun on different substrates with varying coefficients of thermal expansion, oxidized by heating in air and reduced to form a metal-ceramic two phase mixture. This method allows the generation of perpendicular magnetic anisotropy by use of residual stresses arising from a coefficient of thermal expansion difference between the film and substrate. Magneto-optical measurements show that the films can have relatively large Kerr and Faraday rotations, and that the metal particles have sufficient vertical magnetic anisotropy to support perpendicular magnetization. The magneto-optical properties of the films are related to the metal particle size, film thickness and substrate choice.
Giant Magnetoresistance of Self-Assembled ErAs Islands in GaAs
Authors: Schmidt D.R. , Ibbetson J.P. , Brehmer D.E. , Palmstrøm C.J. , Allen S.J. 
Published: April 2011

ABSTRACTWe have integrated nanometer-sized ErAs islands in GaAs, resulting in a nano-composite of paramagnetic particles in a semiconductor. Negative giant magnetoresistance of up to four orders of magnitude is observed at low temperatures. We can control the density and size of the ErAs islands, making this an ideal system to investigate transport in magnetic nano-structures.
Strain Effects in Superlattices of Diluted Magnetic Semiconductor ZnTe/Zn1-xMnxTe
Authors: Chen Chenjia , Chen Xi , Li Xiaoli , Li Haitiao , Wang Xuezhong , Ling Zhen , Wang Jie , Wang Xun 
Published: April 2011

ABSTRACTZnTe/Zn1-xMnxTe superlattices were grown on GaAs (001) substrates by molecular beam epitaxy. The multi-phonon processes including overtones and combinations of optical phonons have been studied by near resonant Raman scattering in the temperature range 13 K to 300 K. The strain arising from lattice mismatch gives rise to a shift in the optical-phonon frequencies. A two-phonon interface mode of superlattice has been observed and identified for the first time. Strain-induced red shifts of exciton energies related to transitions from the conduction subband to the light-hole and heavy-hole subband have been found by photoreflectance measurements. Experimental results agree well with the calculated strain-induced shift in superlattices.
Stability of Nitrogen in Sputtered Iron Nitride thin films and Multilayers
Authors: Chatbi H. , Vergnat M. , Bobo J. F. , Hennet L. 
Published: April 2011

ABSTRACTDifferent phases of FeN thin films and Fe/FeN multilayers were prepared by reactive rf sputtering. The release of nitrogen and the crystallographic transformations during annealing were monitored by thermal desorption spectrometry and X-ray diffraction experiments. Finally, the diffusivity of nitrogen in the γ-Fe4N phase was evaluated.
Investigation of Anisotropy Effects and Interlayer Exchange Coupling by Locally Resolved Photothermally Modulated Ferromagnetic Resonance
Authors: Meckenstock R. , Pelzl J. , Frait Z. 
Published: April 2011

ABSTRACTThe photothermally modulated ferromagnetic resonance (PM-FMR) has been successfully applied to investigate the position dependence of FMR properties of wedged Fe-samples. The temperature dependence of the surface contribution to the anisotropy could be separated from the demagnetizing field with high accuracy. The oscillating first order interlayer exchange coupling and the anisotropy fields of the Fe-films of a Fe/Cr-wedge/Fe-sample (3.0/0.7–2.8/2.0 nm) were deduced from PM-FMR spectra.
Molecular Self-Assembly of Fe3O4/Polyimide Nanocomposite Films (I)
Authors: Liu Yanjing , Wang Anbo , Claus Richard O. , Jiang Eric 
Published: April 2011

ABSTRACTLayer-by-layer molecular self-assembly of nanosized magnetite (Fe3O4) particles and polyimide precursor molecules into multilayer ultrathin films has been accomplished on single crystal silicon and quartz substrates. This process involves the alternate dipping of a substrate into an aqueous solution of cationic polymer which coats on nanoscale Fe3O4 particles as a stabilizer followed by dipping into an aqueous solution of anionie polyimide precursor (polyamic acid salt, PAATEA). The growth process and the structure have been characterized using UV-vis spectroscopy, FT-IR, and scanning electron microscopy. The results demonstrate that well-ordered uniform monolayer and multilayer magnetic films have been formed on silicon and silica surfaces.
Theoretical Investigations on the Magneto-Optical Properties of Transition Metal Multilayer and Surface Systems
Authors: Ebert H. , Perlov A. , Yaresko A. N. , Antonov V. N. , Uba S. 
Published: April 2011

ABSTRACTResults of theoretical investigations on the magneto-optical Kerr-effect in layered systems are presented that are based on a fully relativistic description of the underlying electronic structure. To investigate the importance of the various sources of the Kerr effect model calculations have been performed. Applications to multilayer systems have been done for systems with non-magnetic spacers having a relatively high (Co/Pd, Co/Pt) as well as a small induced magnetic moment (Co/Cu) and comparison with experiment is made. To investigate surface layer systems the use of auxiliary model multilayer systems is explored.
Magnetic Stripe Domains in Fe/Ni Multilayers
Authors: Donzelli O. , Vatucello G. , Nizzoli F. , Palmeri D. , Lucari F. , D'Orazio F. 
Published: April 2011

ABSTRACTMagnetic Fe/Ni multilayers, investigated by Magnetic Force Microscopy (MFM), show a stripe domains structure in which the magnetization is oriented in the film plane. This structure is attributed to the equilibrium configuration between competing in-plane anisotropy of the Ni layers and perpendicular anisotropy due to the thin Fe layers.
Magnetoresistance Effects in Granular Thin Layers Formed by High Dose Iron Implantation Into Silicon
Authors: Wong S.P. , Cheung W.Y. 
Published: April 2011

ABSTRACTHigh dose iron implantation into silicon substrates has been performed with a metal vapor vacuum arc ion source to doses ranging from 5×1016 to 2×1017 cm'2 at various beam current densities. The magnetoresistance (MR) effects in these implanted granular layers were studied at temperatures from 15K to 300K. A positive MR effect, i.e., an increase in the resistance at the presence of a magnetic field, was observed at temperatures lower than about 40K in samples prepared under appropriate implantation conditions. The magnitude of the MR effect, defined as ΔR/Ro ≡ (R(H)-Ro)/Ro where R(H) and Ro denote respectively the resistance value at a magnetic field intensity H and that at zero field, was found to depend not only on the implantation dose but also on the beam current density. This is attributed to the beam heating effect during implantation which affects the formation of the microstructures. The ratio δR/Ro was found to attain high values larger than 400% for some samples at low temperatures. The dependence of the MR effects on temperature, implantation dose, and beam current density will be presented and discussed in conjunction with results of transmission electron microscopy.
Observation of an Exponential FeSi Spacer Thickness Dependence of the Antiferromagnetic Exchange Coupling in Fe/Si-Based Multilayers
Authors: Kohlhepp J.T. , De Vries J.J. , Den Broeder F.J.A. , Coehoorn R. , Jungblut R.M. , Reinders A. , Strijkers G.J. , Smits A.A. , Mde Jonge W.J. 
Published: April 2011

ABSTRACTThe magnetic interlayer exchange coupling in Fe/Si-based thin film structures employing sputtered multilayers with variations of Si-alloyed Fe for the magnetic layers and Fe-alloyed Si spacers, as well as wedge-shaped MBE-grown Fe/Si/Fe sandwich samples has been systematically studied. From structural and magnetic analysis it is concluded that ultrathin Si and FexSi100-x (x < 50) spacer layers transform into a crystalline iron suicide with a composition close to Fe50Si50. The exchange coupling mediated by this metallic suicide is antiferromagnetic and depends on the spacer thickness in an exponential, i.e. non-oscillatory, manner with a universial characteristic decay length of 3–4 Å at room temperature. This observation can be qualitatively explained within the framework of a recent coupling theory on the premise that the FeSi interlayer has the metastable CsCl(B2)-structure.
Giant Magnetoresistance Induced by Ultrathin Magnetic Layers
Authors: Strijkers G.J. , Swagten H.J.M. , Mettler A.H.M. , Willekens M.M.H. , De Jonge W.J.M. 
Published: April 2011

ABSTRACTWe introduce an interface selective structure, composed of a spin-valve on top of which a thick nonmagnetic back layer is deposited as a straightforward experimental tool to measure the GMR induced by ultrathin magnetic layers. The interface selectivity of spin-dependent scattering is evidenced by calculations and illustrated in both Co/Cu/Co and Ni80Fe20/Cu/Ni80Fe20 spin-valves by an almost discontinuous behavior in the GMR ratio. The temperture dependence of the extremely short length scale associated with this discontinuity is discussed in relation to the structure of ultrathin ferromagnetic layers.
Effects of Electron Beam Exposure on Poly(Arylene Ether) Dielectric Films
Authors: Drage J. S. , Yang J. J. , Choi D. K. , Katsanes R. , Lau K. S. Y. , Wang S.-Q. , Forester L. , Schilling P. E. , Ross M. 
Published: April 2011

AbstractThis paper presents a study of the effects of electron beam (e-beam) exposure on the chemical and physical properties of FLARE™ 1.0X, a non-fluorinated member of the FLARE™ family of poly(arylene ether) dielectric coatings. Spin-coated films of this poly(arylene ether) were cured by large-area e-beam exposure, as well as by conventional thermal processing. Neither swelling nor dissolution was observed for the e-beam cured films after immersion in N-methylpyrrolidone (NMP) at 90 °C for 1 hour. The glass transition temperature (Tg) for films cured with a low e-beam dose is slightly higher than, or nearly the same as, the (Tg) for thermally-cured films (∼ 270 °C). However, the Tg for films cured with a high e-beam dose exceeds 400 °C. Dielectric constants of e-beam cured films and thermally cured films are nearly the same. FTIR spectra of FLARE™ films obtained before and after e-beam exposure suggest that e-beam curing does not induce any significant change in the chemical structure. Increased solvent resistance, higher Tg, and low dielectric constant are properties that make this e-beam cured poly(arylene ether) film an excellent candidate for interlevel dielectric integration processes.
Thermomechanical Properties of Hydrogen Silsesquioxanes
Authors: Shih W.-Y. , Zhao J.-H. , McKerrow A. J. , Ryan E. T. , Taylor K. J. , Ho P. S. 
Published: April 2011

AbstractUsing Si and GaAs substrates, the coefficient of thermal expansion (CTE) and the bi-axial modulus of thin hydrogen silsesquioxanes (HSQ) films are deduced by means of wafer curvature measurement. The same properties of plasma-enhanced CVD oxide are also reported.
Parylene Copolymers
Authors: Taylor Kelly J. , Eissa Mona , Gaynor Justin F. , Jeng Shin-Puu , Nguyen Hoan 
Published: April 2011

AbstractImprovements in the properties of Parylene may enable their use in high performance integrated circuits. Parylenes are a class of polymers formed by chemical vapor deposition which nearly meet the high standards of the low-k triumvirate, namely, 1) adhesion, particularly to SiO2, 2) thermal stability above 400 Celsius, and 3) permittivity less than 2.7. Parylene-N has been incorporated into both aluminum-1 and copper-2 based metallization schemes, however, improvements in the adhesion and thermal stability are still needed to simplify and increase the robustness of the integration schemes. Additionally, a reduction in the permittivity would be beneficial from both device performance and extendibility points-of-view. We have synthesized various Parylene-N-based copolymers with improved adhesion, thermal stability, and permittivity. We discovered that a copolymer of tetravinyl-tetramethyl-cyclotetrasiloxane and Parylene-N has a permittivity of close to 2.1 and both the adhesion to SiQ2 and thermal stability are measurably improved compared to the homopolymer.
Chemical Vapor Deposited Teflon Amorphous Fluoropolymer as an Interlevel Dielectric Material for Low Power Integrated Circuits
Authors: Sharangpani R. , Singh R. 
Published: April 2011

AbstractThe development of materials with dielectric constant (K) less than SiO2(K=3.9) is essential to meet the stringent speed, power dissipation and crosstalk requirements that are driving the low power integrated circuit (IC) paradigm. Both the low K dielectric and the processing methodology used for it should satisfy several important criteria before the technique can be accepted in future mainstream low power IC manufacturing. We had reported earlier a chemical vapor deposition (CVD) technique for the deposition of DuPont's Teflon amorphous fluoropolymer 1600 (bulk K=1.93) using the principle of direct liquid injection. The processing was carried out with and without an ultra violet (UV) light source in a computerized rapid isothermal processing (RIP) system.Recently, we have extensively characterized the films and examined the suitability of our technique in light of some of the requirements of the future IC industry. Our results indicate that the processed films exceed several of the established dielectric performance standards outlined in recent roadmaps for sub 0.25 μm ICs. The film properties were improved when the UV source was used during processing. CVD processed films in general demonstrated significant improvements in terms of manufacturability, throughput, cost, and dielectric properties over the same films processed by alternate techniques.
Adhesion and Dielectric Strength of Ultra-Low Dielectric Constant PTFE Thin Films
Authors: Rosenmaver C.T. , Bartz J. W. , Hammes J. 
Published: April 2011

AbstractPrevious work has demonstrated the potential of polytetrafluoroethylene (PTFE) thin films for ULSI applications. The films are deposited from PTFE nanoemulsions. They have an ultra-low dielectric constant of 1.7 to 2.0, a leakage current of less than 1.0 nA/cm2 @ 0.2 MV/cm and a dielectric strength of from 0.5 to 2.4 MV/cm. They are thermally stable (isothermal weight loss < 1.0 %/hr at 450 °C), uniform (thickness standard deviation < 2%), and have excellent gap-fill properties (viscosity of 1.55 cP and surface tension of 18 mN/m). The films are inert with respect to all known semiconductor process chemicals, yet they are easily etched in an oxygen plasma.This paper discusses the processing technology that has been developed to process PTFE films with these properties. Specifically, it addresses two recent discoveries: 1) Good adhesion of spin-coated PTFE to SiO2 surfaces; and 2) high dielectric strength of PTFE thin films spin-coat deposited onto rigid substrates. The adhesion-promoting and thermal treatments necessary to produce these properties are detailed. Stud pull test results and test results from metal-insulator-metal (MIM) capacitor structures are given.
Thermal Stability Study of the Interconnect System with Fluorinated Silicate Glass as IMD Layers
Authors: Li Weidan , Catabay Wilbur 
Published: April 2011

AbstractWhile fluorinated silicate glass (FSG) has been proposed for low k inter-metal dielectric (IMD) applications in a multi-level interconnect system either as the only IMD material, or as one of the materials for a multi-layer IMD system, thermal stability of the FSG film and its impact on device reliability remain a concern for this application. In this study, SIMS, SEM, and optical microscope analyses were carried out to evaluate the thermal stability of the FSG films and the possible reactions between FSG and metals. It was observed that at elevated temperatures fluorine tends to diffuse into an undoped oxide film rather than be desorbed. The data indicate that F diffuses 3.5 times faster in a silicon oxide film than in a silicon nitride film. Sub-half micron devices were processed with FSG as IMD layers. The devices were tested using an intensive thermal stability test methodology. A TiSi2 reaction with F which diffused from the FSG film was observed under optical microscopy. This reaction caused TiSi2 delamination. Electrical characterization of devices was performed before and after the thermal stability test. Although the device performance did not change greatly, the reaction certainly affects the long term device reliability (vide infra). Barrier materials were investigated to solve the F diffusion problem. With the proper diffusion barrier, the problem of the fluorine reaction with TiSi2 and subsequent metal blistering was eliminated.
Thermal Stresses, Interfacial Reactions and Microstructures of Al/Ti and Al/TiN Thin Films Encapsulated by SiOF
Authors: Tseng Wei-Tsu , Chen Li-Wen , Tu G.-C. 
Published: April 2011

AbstractVariations in stress and grain size of Ti- and TiN- capped Al thin films passivated by fluorinated silicon dioxide (SiOF) during repetitive thermal cycling are investigated. The amount of stress relaxation, elastic and plastic behavior of these thin film structures are compared. Ti and TiN cap layers strengthen the single Al film significantly while the presence of SiOF induces plastic deformation of metal layers. Less grain growth is associated with a dielectric passivated Al film. The penetration of fluorine into Al upon annealing can be reduced by a TiN barrier layer.
Recent Advances in Low K Polymeric Materials
Authors: Carter K. R. 
Published: April 2011

AbstractAs microelectronic device dimensions decrease and functionality density increases, a change in interconnect materials, both conductors and insulators must change from currently used materials. To this end, we are actively in search of low dielectric constant materials that can be integrated into integrated circuit production. The greatest limiting factor in materials qualification are the stringent IC processing conditions (thermal stability, resistance to chemical/mechanical treatments). Current specifications for back-end-of-the-line (BEOL) thin film insulators call for materials with dielectric constants of 3.0–3.5 and turn of the century CMOS devices may require materials with dielectric constants approaching 2.0. While there are a number of possible candidates for current uses, the list of usable materials with dielectric constants <3.0 is very limited. Future low K candidates being examined include fluorinated polyimides and porous materials.
Temperature and Moisture Dependence of Dielectric Constant for Bulk Silica Aerogels
Authors: Hrubesh L.W. , Buckley S. R. 
Published: April 2011

AbstractThe dielectric constants of silica aerogels are among the lowest measured for any solid material. The silica aerogels also exhibit low thermal expansion and are thermally stable to temperatures exceeding 500°C. However, due to the open porosity and large surface areas for aerogels, their dielectric constants are strongly affected by moisture and temperature. This paper presents data for the dielectric constants of silica aerogels as a function of moisture content at 25 °C, and as a function of temperature, for temperatures in the range from 25 °C to 450°C. Dielectric constant data are also given for silica aerogels that are heat treated in dry nitrogen at 500°C, then cooled to 25°C for measurements in dry air. All measurements are made on bulk aerogel spheres at 22GHz microwave frequency, using a cavity perturbation method. The results of the dependence found here for bulk materials can be inferred to apply also to thin films of silica aerogels having similar nano-structures and densities.
The Small Angle Cleavage Technique: An Update
Authors: Walck Scott D. , McCaffrey John P. 
Published: April 2011

AbstractThe Small Angle Cleavage Technique is a relatively simple and inexpensive method of producing superior cross sectional TEM specimens. For speed of preparation, it is unsurpassed. One limitation is that the technique does require the substrate material to cleave or fracture. For this reason, it has been applied almost exclusively to semiconductor materials. Recently, the technique has been extended to other substrates such as glass, silicon carbide, quartz, sapphire, and other hard materials. It is particularly well suited for rapidly examining coatings and thin films very soon after they are deposited. Several procedures have been added or modified to the original technique developed by McCaffrey to simplify the technique. The steps are presented in a detailed pictorial outline form. A method for mounting the cleaved samples utilizing a commercially available grid is presented. In addition, the advantages that the special geometry of the prepared samples have when mounted properly in a double-tilt holder are discussed with respect to the angular range of tilting experiments that are now possible in the TEM.