bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epitaxial Co/NiAl Thin Film Growth on Si Substrates
Authors: Gong Heng , Yang Wei , Lambeth David N. , Laughlin David E. 
Published: April 2011

ABSTRACTQuad-crystal Co/NiAI/Ag thin films were epitaxially grown on hydrofluoric acid etched Si(111) single crystal substrates by sputter deposition. The orientation relationship was studied by x-ray θ;/2θ; diffraction and pole figure Φ-scan, and it was determined to be Co(image1) 11 NiAI(1 10) 11 Ag(111) 11 Si(1 11). The Ag layer contains two twin-related orientations of grains. NiAI grows with three variants of grains on the Ag(1 11) layer. Since Co(image1) contains grains with four possible easy axis directions when grown on each NiAl variant, the quad-crystal media consist of grains with twelve easy axis directions and exhibit nearly isotropic in-plane magnetic properties. Meanwhile, uni-crystal Co(image2)/NiAl(1 12) films were also epitaxially grown on Ag(110)/HF-Si(110) templates. The orientation relationships determined from these epitaxial films were very useful in understanding the texture evolution of the Co alloys on NiAl. It indicates that the Co (image2) texture evolution on the (110) texture of NiAl on amorphous substrates, such as NiP/A1Mg or glass, is due to a difficult to observe NiA1 (112) texture on the top of the (110) texture.
The Influence of Microstructure on the Magnetic Properties in Nanostructured Copt Li0Thin Films
Authors: Jeong S. , Mchenry M. E. , Laughlin D. E. 
Published: April 2011

ABSTRACTWe have applied the Neel's spin pair potential model to model the dependence of magnetocrystalline anisotropy on the long range order parameter. We have produced CoPt nanoscale thin films, with and without an immiscible second phase, by RF and DC magnetron sputtering. These thin films showed a shoulder in their magnetic hysteresis, indicative of a disordered soft magnetic phase for samples annealed above 600 °C while it was barely detectable in 500–600 °C annealed samples. A (111) texture is observed in as-deposited and annealed films is identified as one of the possible contributions to the lower coercivity squareness S* and perpendicular magnetic properties. Micromagnetic calculations confirmed a poor exchange interaction, identified rotational energy barriers and inferred that the ordered region was not fully ordered. The initial stage of ordering clearly showed a discontinuous type transformation.
Spin-Valve GMR Films Based on Antiferromagnetic NiMn
Authors: Anderson Geoff , Huai Yiming , Miloslavsky Lena 
Published: April 2011

ABSTRACTIn this work we have investigated the magnetic and structural properties of spin-valve films exchange biased by CoFe/NiMn compared to CoFe/lrMn spin valves. A spin-valve film of structure Ta/NiFe/CoFe/Cu/CoFe/NiMnITa showed a giant-magnetoresistance of 5.5% with a Hex∼850 Oe after annealing. Structural ordering of the NiMn in an fct phase after annealing has been observed using x-ray diffraction, with the data exhibiting pure fct(111) texture. The thermal stability of both the exchange pinning and magnetoresistance of NiMn spin-valves was evaluated. The blocking temperature (Tb) of this film is 400°C, compared to 225°C for IrMn based spin-valve films (IrMn thickness ∼50 Å). Blocking temperature distribution and remnant blocking temperature measurements also suggest that NiMn based spin-valves have far superior pinning stability with temperature than IrMn based spin-valves. Magnetoresistance measurements show a linear decrease with temperature due to electron-phonon scattering with the ∆R/R being reduced by 33% at 150°C (as compared to a 50% decrease for IrMn based spinvalves). Extended annealing at 150°C did not effect spin-valve performance, with ∆R/R and R being constant over 60 hours, suggesting that no appreciable interdiffusion is occurring.
Aggressively Scaled P-Channel Mosfets With Stacked Nitride-Oxide-Nitride, N/O/N, Gate Dielectrics
Authors: Wu Yider , Lucovsky Gerald 
Published: April 2011

ABSTRACTUltrathin (tox,eq < 2.0 nm) Si3N4/SiO2(hereafter N/O) gate dielectrics with improved interface characteristics compared to devices with thermal oxides have been formed by remote plasma enhanced CVD of Si3N4onto oxides. If the Si-Si02 interface is intentionally nitrided prior to the Si3N4deposition, the increased physical thickness of the N/O stack combined with the interfacial nitridation reduces the direct tunneling current by more than two orders of magnitude. The ensuing device structure can then be characterized as N/O/N. The top nitride layer is also an effective boron diffusion barrier improving short channel characteristics in p+-poly PMOSFETs. In addition, nitrogen can also be transported to the silicon/dielectric interface during post-deposition RTAs, and this reduces degradation of transconductance during hot carrier stressing.
A Tale of Two Precursors: UHV-CVD of TiO2 From Titanium Nitrate and Titanium Isopropoxide
Authors: Gladfelter Wayne L. , Taylor Charles J. , Gilmer David C. , Colombo Daniel G. , Wilk G. D. , Campbell Stephen A. , Roberts Jeff 
Published: April 2011

ABSTRACTA side-by-side comparison of the TiO2 deposition kinetics and the corresponding film microstructures using titanium(IV) isopropoxide and anhydrous titanium(IV) nitrate was conducted at low pressures (< 10−4 Torr) in an ultrahigh vacuum chemical vapor deposition reactor. Titanium(IV) nitrate exhibited a lower activation energy of reaction (Er= 98 kJ/mol) which allowed deposition at lower temperatures compared to titanium(IV) isopropoxide (Er= 135 kJ/mol). Comparison of the microstructures of films deposited at similar temperatures revealed significant differences in the reaction rate limited kinetic regime. As the growth rates of the two precursors converged in the flux-limited regime, the respective microstructures became indistinguishable.
Characterization of the Seed SiO2 Layer in Stacked SiO2-Ta2O5 Gate Dielectrics
Authors: Roy Pradip K. , Laughery Michael A. , Chacon Carlos M. , Kanan Ayman M. , Daugherty Thomas 
Published: April 2011

ABSTRACTA major hurdle in the gate dielectric scaling using conventionally grown SiO2 has been excessive tunneling that occurs in ultra-thin (<25Å) SiO2. High dielectric constant materials have high concentrations of bulk fixed charge, unacceptable levels of Si-Ta2O5 interface trap states, and low Silicon interface carrier mobilities. Stacked Ta2O5 gate dielectrics have alleviated these issues with significant improvements in leakage, tunneling, charge trapping behavior, and interface substructure. Transistors fabricated using this stacked gate dielectric exhibit excellent sub threshold, saturation, and drive currents. In this study, we have characterized the first SiO2 (8-12Å) layer of the SiO2-Ta2O5 stack by ThermaWave (TWI 5240SE) absolute ellipsometry (AE) using He-Ne (λ= 630nm) laser light source and by corona oxide semiconductor (COS) non-contact techniques. We have also monitored the kinetics of a thin hydrocarbon layer deposition on top of these films that can be removed by simple heat treatments (250°C - 400°C). Electrical thickness (Tox) of these oxides measured by COS indicates this hydrocarbon layer has no impact on Tox. Stacked Ta2O5 was synthesized by metal organic chemical vapor deposition (MOCVD) of a 50-75Å thick Ta2O5 layer at 480°C, 300mTorr followed by an in-situ 550°C UV-03 anneal to densify the Ta2O5 film and grow an additional 5Å SiO2 layer underneath the first grown SiO2 layer resulting in an effective SiO2 thickness of 25-30Å (process 1). We have done exactly the same deposition schedule after chemically removing the first LP grown SiO2 layer resulting in an effective SiO2 thickness of 15-20Å (process 2). Transistors are now fabricated for our sub-0.16μm CMOS technologies. These stacked films indicated excellent charge trapping (Dit, Vfb, Qtot), leakage and tunneling characteristics from COS electrical measurements.
Alternate Gate Oxides for Silicon Mosfets Using High-k Dielectrics
Authors: Billman C. A. , Tan P. H. , Hubbard K. J. , Schlom D. G. 
Published: April 2011

ABSTRACTHigh K (dielectric constant) and silicon-compatibility are essential for an alternative gate dielectric for use in silicon MOSFETs. Thermodynamic data were used to comprehensively evaluate the thermodynamic stability of binary oxides and binary nitrides in contact with silicon at 1000 K. Using the Clausius-Mossotti equation and ionic polarizabilities, the K of all known inorganic compounds composed of Si-compatible binary oxides was estimated. A ranked list of alternate gate oxide candidates that are likely to possess both high K and silicon-compatibility is given.
Crystalline Oxides on Silicon – Alternative Dielectrics for Advanced Transistor Technologies
Authors: McKee Rodney , Walker Fred , Chisholm Matt 
Published: April 2011

ABSTRACTSince the advent of the integrated circuit in 1959 and the introduction of MOS capacitors in the early ‘60’s, electronic technology has relied on silica (SiO2) as the gate dielectric in a field effect transistor. However, silica-based transistor technology is approaching fundamental limits. Feature-size-reduction and the ever-demanding technology roadmaps have imposed scaling constraints on gate oxide thickness to the point where excessive tunneling currents make transistor design untenable; an alternative gate dielectric is needed. Crystalline oxides on silicon (COS), simply by virtue of their high dielectric constants, could fundamentally change the scaling laws for silicon-based transistor technology. More importantly, COS could provide the opportunity for an entirely new device physics based on anisotropic response of crystalline oxides grown commensurately on a semiconductor. In this paper, we report that high dielectric constant alkaline earth and perovskite oxides can be grown in perfect registry with silicon. Commensurate heteroepitaxy between the semiconductor and the oxide is established via a sequenced transition that uniquely addresses the thermodynamics of a layer-by-layer energy minimization at the interface. The perfection of the physical structure couples directly to the electrical structure, and we thus obtain the unparalleled result of an equivalent oxide thickness of less than I nm in a MOS capacitor. With this demonstration it is apparent that COS presents a functional alternative to SiO2. With COS, a transistor gate can not only exhibit a much higher dielectric response, but add entirely new capabilities such as logic-state retention with the anisotropic response of ferroelectric polarization in a ferro-gated device. COS is the basis for fundamental change in semiconductor technology.
Nitrogen (N2) Implantation to Suppress Growth of Interfacial Oxide in Mocvd Bst and Sputtered Bst Films
Authors: Nieh Renee , Qi Wen-Jie , Jeon Yongjoo , Lee Byoung Hun , Lucas Aaron , Kang Laegu , Lee Jack C. , Gardner Mark , Gilmer Mark 
Published: April 2011

ABSTRACTBa0.5Sr0.5TiO3 (BST) is one of the high-k candidates for replacing SiO2 as the gate dielectric in future generation devices. The biggest obstacle to scaling the equivalent oxide thickness (EOT) of BST is an interfacial layer, SixOy, which forms between BST and Si. Nitrogen (N2) implantation into the Si substrate has been proposed to reduce the growth of this interfacial layer. In this study, capacitors (Pt/BST/Si) were fabricated by depositing thin BST films (50Å) onto N2 implanted Si in order to evaluate the effects of implant dose and annealing conditions on EOT. It was found that N2 implantation reduced the EOT of RF magnetron sputtered and Metal Oxide Chemical Vapor Deposition (MOCVD) BST films by ∼20% and ∼33%, respectively. For sputtered BST, an implant dose of 1×1014cm−;2 provided sufficient nitrogen concentration without residual implant damage after annealing. X-ray photoelectron spectroscopy data confirmed that the reduction in EOT is due to a reduction in the interfacial layer growth. X-ray diffraction spectra revealed typical polycrystalline structure with (111) and (200) preferential orientations for both films. Leakage for these 50Å BST films is on the order of 10−8 to 10−5 A/cm2—lower than oxynitrides with comparable EOTs.
Scanning Probe Microscopy (SPM) for the Investigation of Local Electrical Properties of High-K Dielectric/Ferroelectric Films
Authors: Landau S.A. , Weiß P.-A. , Junghans N. , Kolbesen B.O. , Adderton D. , Schindler G. , Hartner W. , Hintermaier F. , Dehm C. , Mazuré C. 
Published: April 2011

ABSTRACTThin films of high-k dielectric/ferroelectric materials such as BaxSr1−xTiO3(BST), PbZrxTi1−xO3(PZT) and SrBi2Ta2O9(SBT) are currently investigated for integration into high-density CMOS technology. Characterization of these materials by SPM techniques combines imaging of the morphology and microstructure of these films and recording of various electrical parameters at the same local area. Using commercial equipment we have investigated electrical properties such as polarization and leakage current behavior of MOD/MOCVD SBT by applying electrostatic force microscopy (EFM) and conducting atomic force microscopy (CAFM). After applying bias voltages of a few volts across the SBT films between the scanning tip and the lower electrode completely polarized/reverse polarized SBT layers could be observed by EFM. Even single crystallite polarization was imaged. However, unexpectedly some films showed incomplete polarization, which may be caused by local electrical field effects. Images taken by C-AFM displayed enhancement of leakage currents in grain boundary regions, in particular at depressions between adjacent crystallites. The results achieved demonstrate that SPM techniques operated in a variety of imaging and measuring modes, provide a tremendous potential in the elucidation of the microscopic properties of high-k materials.
Formation of High Quality Oxynitride Gate Dielectrics by High Pressure Thermal Oxidation of Si in NO
Authors: Song S. C. , Lee C. H. , Luan H. F. , Kwong D. L. , Gardner M. , Fulford J. , Allen M. , Bloom J. , Evans R. 
Published: April 2011

ABSTRACTIn this paper, we report a novel low thermal budget process (<800°C) for engineered ultra thin oxynitride dielectrics with high nitrogen concentration (>5% a.c.) using vertical high pressure (VHP) process. VHP grown oxynitride films show >1 OX lower leakage current, higher drive current and superior hot-carrier reliability compared to control SiO2 of identical thickness (Tox,eq) grown by RTP in O2.
Ostwald Ripening of {113} Defects Precursors and Transient Enhanced Diffusion
Authors: Manninoo Giovanni , Cowem Nicholas E.B. , Stolk Peter A. , Roozeboom Fred , Huizing Hendrik G.A. , Berkum Jurgen G.M. van , Boer Wiebe B. de , Cristiano Filadelfo , Claverie Alain , Jaraiz Martin 
Published: April 2011

ABSTRACTThe ripening of ion-beam generated point defects into extended defects has been investigated in detail. The interstitial supersaturation has been extracted from boron marker-layer diffusion after annealing under non-equilibrium defect conditions. We measured a very high initial supersaturation followed by a decrease over many orders of magnitude with a characteristic “plateau” related to the presence of {113} defects. A continuum inverse model has been used to properly describe the ripening of point defects into clusters and their evolution in the presence of a remote sink, e.g. the surface. It evidences that a nonconservative Ostwald ripening process takes place inside the defect band during the annealing and sustains the interstitial supersaturation. The model reveals moreover an oscillatory behaviour of dissociation energies of the nanometer-sized defects which are responsible for the initial high supersaturation. These defects are believed to be {113} precursors.
Ultra-Shallow Junctions by Ion Implantation and Rapid Thermal Annealing: Spike-Anneals, Ramp Rate Effects
Authors: Agarwal Aditya , Gossmann Hans-J. , Fiory Anthony T. 
Published: April 2011

ABSTRACTOver the last couple of years rapid thermal annealing (RTA) equipment suppliers have been aggressively developing lamp-based furnaces capable of achieving ramp-up rates on the order of hundreds of degrees per second. One of the driving forces for adopting such a strategy was the experimental demonstration of 30nm p-type junctions by employing a ramp-up rate of ≈400°C/s. It was subsequently proposed that the ultra-fast temperature ramp-up was suppressing transient enhanced diffusion (TED) of boron which results from the interaction of the implantation damage with the dopant. The capability to achieve very high temperature ramp-rates was thus embraced as an essential requirement of the next generation of RTA equipment.In this paper, recent experimental data examining the effect of the ramp-up rate during spike-and soak-anneals on enhanced diffusion and shallow junction formation is reviewed. The advantage of increasing the ramp-up rate is found to be largest for the shallowest, 0.5-keV, B implants. At such ultra-low energies (ULE) the advantage arises from a reduction of the total thermal budget. Simulations reveal that a point of diminishing return is quickly reached when increasing the ramp-up rate since the ramp-down rate is in practice limited. At energies where TED dominates, a high ramp-up rate is only effective in minimizing diffusion if the implanted dose is sufficiently small so that the TED can be run out during the ramp-up portion of the anneal; for larger doses, a high ramp-up rate only serves to postpone the TED to the ramp-down duration of the anneal. However, even when TED is minimized at higher implant energies via high ramp-up rates, the advantage is unobservable due to the rather large as-implanted depth. It appears then that while spike anneals allow the activation of ULE-implanted dopants to be maximized while minimizing their diffusion the limitation imposed by the ramp-down rate compromises the advantage of very aggressive ramp-up rates.
In-Situ Optical Characterization of Titanium Nitride Thin Films for Applications in Microelectronics
Authors: Patsalas P. , Logothetidis S. , Dimitriadis C.A. 
Published: April 2011

ABSTRACTTitanium Nitride (TiNx) thin films were deposited on Si(100) by reactive magnetron sputtering. The varied deposition conditions were the substrate temperature (Td) (27 - 650 °C) and the negative bias voltage (Vb) applied to the substrate (0 - 200 V) in order to produce TiNx films with various compositions and structural characteristics. The deposition process was monitored in-situ by Spectroscopic Ellipsometry in the spectral range 1.5–5.5 eV. Determination of the film composition was made through the measured screened plasma energy ωps while the electrical resistivity of TiNx was studied in terms of the unscreened plasma energy ωpu. ωpu was calculated by an optical model including a Drude term and Lorentz oscillator terms and their dependence on Td and Vb was studied. The ωpu was found to increase with Vb until a saturation value was obtained. The saturation value of ωpu depends on the Td.ωpu describes better the TiNx films, since it is directly correlated with their metallic character in terms of the electrical resistivity.
Study of Natural Oxidation of Ultra-Thin Aluminum Layers with In-Situ Resistance Measurement
Authors: Fery C. , Bailey W.E. , Yamada K. , Wang S.X. 
Published: April 2011

ABSTRACTExposure to oxygen (1 Torr) at room temperature of thin Al films deposited by UHV ion beam sputtering has been studied using an in-situ resistance measurement set-up. Two lock-in amplifiers allow low noise data acquisition. By monitoring the conductance during deposition and oxidation we can deduce the consumed Al thickness as a function of exposure time (t). It is found that the Al/vacuum interface is diffuse for electron scattering. A two-stage mechanism for natural oxidation is revealed: fast growth (for t<10s) followed by a slow logarithmic growth. A simple model based on interface reactions and place exchange describes the experimental results. The conductance drop after 5 minutes of oxidation is found to decrease for initial Al thicknesses below 30A. This suggests the oxidation rates slow down for thin initial Al thicknesses.
Secondary Grain Growth in Thin Films
Authors: Thompson C. V. , Smith Henry I. 
Published: April 2011

AbstractNormal grain growth in thin films leads to columnar grains with sizes roughly equal to the film thickness. In subsequent grain growth, a minor fraction of the grains continue to grow at appreciable rates, leading initially to a bimodal grain size distribution and ultimately to a monomodal distribution of grains with sizes much larger than the film thickness. Those grains which continue to grow, secondary grains, often have uniform or restricted texture, suggesting that in such cases surface energy minimization plays an important role in driving their preferential growth. Surface-energy-driven secondary grain growth can, in principle, lead to single crystal films. Turnbull and co-workers were among the first to apply rate theory to the analysis of grain boundary motion, grain growth, and recrystallization. These models have been adapted to describe surface-energy-driven secondary grain growth in thin films. Recent experiments on secondary grain growth in thin metallic and semiconductor films are reviewed. It has been shown that film thickness, film composition and surface topography have pronounced effects on growth rates, final grain sizes and orientations.
Formation of Metallic Nanoclusters in SiC by MeV Ion Implantation
Authors: Ila D. , Williams E. K. , Elsamadicy A. , Gasic B. , Poker D. B. , Hensley D. K. , George M. A. , Ayoub M. A. , Larkin David J. 
Published: April 2011

ABSTRACTWe present the results of our investigation of producing nanoclusters of gold, silver, copper and tin in 6H-SiC. This is accomplished by implanting 1.0 MeV Au, 2.0 MeV Ag, 2.0 MeV Cu, and 160 keV Sn into the Si face of SiC at room or elevated temperature followed by annealing at various temperatures. Using optical absorption spectrophotometry, we determined the location of the absorption band for each metal nanocluster in SiC. Elevated temperature implantation reduces optical absorption due to ion implantation induced defects. Using the Mie theory, we determined the index of refraction in the implanted volume.
Z-Contrast Stem Imaging and Eels of CdSe Nanocrystals: Towards the Analysis of Individual Nanocrystal Surfaces
Authors: Kadavanich A.V. , Kippeny T. , Erwin M. , Rosenthal S. J. , Pennycook S. J. 
Published: April 2011

ABSTRACTWe have applied Atomic Number Contrast Scanning Transmission Electron Microscopy (Z-Contrast STEM) and STEM/EELS (Electron Energy Loss Spectroscopy) towards the study of colloidal CdSe semiconductor nanocrystals embedded in MEH-PPV polymer films. Z-Contrast images are direct projections of the atomic structure. Hence they can be interpreted without the need for sophisticated image simulation and the image intensity is a direct measure of the thickness of a nanocrystal. Our thickness measurements are in agreement with the predicted faceted shape of these nanocrystals.Our unique 1.3Å resolution STEM has successfully resolved the sublattice structure of these CdSe nanocrystals. In [010] projection (the polar axis in the image plane) we can distinguish Se atom columns from Cd columns.EELS measurements on individual nanocrystals indicate a significant amount (equivalent to 0.5–1 surface monolayers) of oxygen on the nanocrystals, despite processing in an inert atmosphere. Spatially resolved measurements at 7Å resolution suggest a surface oxide layer.