bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic Anisotropy in Electrodeposited CO Films and spin-valves on Gaas Substrates
Authors: Attenborough K. , Cerisier M. , Boeve H. , De Boeck J. , Borghs G. , Celis J.-P. 
Published: April 2011

ABSTRACTWe have studied the magnetic and structural properties of thin electrodeposited Co and Cu layers grown directly onto (100) n-GaAs and have investigated the influence of a buffer layer. A dominant fourfold anisotropy with a uniaxial contribution is observed in 10 nm Co electrodeposited films on GaAs. An easy axis is observed in the [001] GaAs direction with two hard axes of differing coercivities parallel to the [011] and [011] directions. For thicker films the easy axes in the [001] direction becomes less pronounced and the fourfold anisotropy becomes less dominant. Co films of similar thicknesses deposited onto an electrodeposited Cu buffer layer were nearly isotropic. From X-ray diffraction 21 nm Co layers on GaAs were found to be hcp with the c-axis tending to be in the plane of the film. The anisotropy is ascribed to the Co/GaAs interface and is held responsible for the unique spin-valve properties seen recently in electrodeposited Co/Cu films.
Pattern Dependent Modeling for CMP Optimization and Control
Authors: Boning D. , Lee B. , Oji C. , Ouma D. , Park T. , Smith T. , Tugbawa T. 
Published: April 2011

In previous work, we have formalized the notions of “planarization length” and “planarization response function” as key parameters that characterize a given CMP consumable set and process. Once extracted through experiments using carefully designed characterization mask sets, these parameters can be used to predict polish performance in CMP for arbitrary product layouts. The methodology has proven effective at predicting oxide interlevel dielectric planarization results.In this work, we discuss extensions of layout pattern dependent CMP modeling. These improvements include integrated up and down area polish modeling; this is needed to account for both density dependent effects, and step height limits or step height perturbations on the density model. Second, we discuss applications of the model to process optimization, process control (e.g. feedback compensation of equipment drifts), and shallow trench isolation (STI) polish. Third, we propose a framework for the modeling of pattern dependent effects in copper CMP. The framework includes “removal rate diagrams” which concisely capture dishing height and step height dependencies in dual material polish processes.
Long Range Order in Ultra-Thin SiO2 Grown on Ordered Si(100)
Authors: Hurst Q.B. , Herbots N. , Shaw J.M. , Floyd M.M. , Smith D.J. , Culbertson R.J. , Grams M.P. , Bradley J.D. , Zimmerman P , Atluri V. 
Published: April 2011

ABSTRACTIn this paper, we investigate the correlation of electrical properties and structure of 1-4 nm thick SiO2 grown on H-passivated Si(100) for ultra-thin gate applications. Ordered (1×1) Si(100) stable in ambient air is obtained at room temperature by wet chemical cleaning. Ion Beam Analysis using a combination of ion channeling and 16O(α,α)16O nuclear resonance yields Si areal densities lower than that of a bulk-terminated Si crystal as calculated by Monte-Carlo simulations. This result indicates shadowing of Si substrate atoms by Si atoms in the thermally grown oxide. Detection of order by ion channeling is supported by Reflection High Energy Electron Diffraction (RHEED). C-V and I-V measurements are generally inconclusive for ultra-thin (1-2 nm) oxides because of leakage and breakdown. Surface charge analysis enables a comparison between ordered oxides and conventional oxides. The results are promising.
Atomic Scale Modeling of the Silicon (100) Thermal Oxidation, A Kinetic Monte Carlo Approach
Authors: Esteve A. , Rouhani M. Djafari , Faurous Ph. , Esteve D. 
Published: April 2011

ABSTRACTIn this paper, we propose an original approach of the silicon (100) dry thermal oxidation modeling that is capable to reproduce the oxidation dynamics at the atomic level and at a large scale comparing with ab initio methods. This approach is based on the use of a Monte Carlo procedure to manage the temporal aspect. In conjunction with experimental literature data, first principle calculations have been carried out with the objective of isolating some elementary oxidation mechanisms, i.e. basic atomic movements and their corresponding energies. This preliminary list of mechanisms is discussed in detail. A growth mechanism allowing the oxide defect generation is proposed. Finally, we present Monte Carlo calculations with the implemented mechanisms where at least three silicon layers are oxidized.
Measuring Interface State Distributions in Ultra-Thin Mos Capacitors with Direct Tunnel Current Leakage
Authors: Song H. , Farmer K. R. 
Published: April 2011

ABSTRACTUsing a leakage-compensated charge (LCCV) technique to obtain static capacitance-voltage (C-V) curves, we extend the standard high-low C-V method for determining the interface state level density, Dit as a function of energy in the silicon band gap to metal-oxide-silicon capacitors in the direct tunneling regime (oxide thickness ∼<3.5 nm). The LCCV technique yields true static C-V curves for oxides at least as thin as 2.8 nm, where the tunnel leakage current is so high that the usual quasistatic C-V measurement is not possible. As applications of this method, Dit is compared for fresh oxides of different tunnel thickness, and Dit is measured before and after constant voltage stress of a 3.5-nm oxide. The stress results indicate, as in other work on thicker oxides, that interface traps are created during the stress, with peak densities both below and above midgap. This approach is expected to be useful for evaluating both ultra-thin oxides and leaky alternate gate dielectrics.
Remote Plasma Enhanced-Metal Organic Chemical Vapor Deposition of Zirconium Oxide/Silicon Oxide Alloy, (ZrO2)1-(SiO2)1−x (x:≤0.5), Thin Films for Advanced High-K Gate Dielectrics
Authors: Wolfe D. , Flock K. , Therrien R. , Johnson R. , Rayner B. , Günther L. , Brown N. , Claflin B. , Lucovsky G. 
Published: April 2011

ABSTRACTA remote plasma enhanced-metal organic chemical vapor deposition (RPE-MOCVD) process was developed for the preparation of non-crystalline (ZrO2)x-(SiO2)1−x (x ≤ 0.5) alloys, targeting the compound composition ZrSiO4with k ∼ 12.5. Shifts in Si LVV and Zr LMM AES energies with respect to elemental values showed that the deposited film was a fully-oxidized zirconium/silicon alloy. FTIR results were consistent with AES, and a Zr-O-Si bonding mode was identified in the spectra. The films were amorphous before and after RTA at 900°C for 30 sec, as monitored via RHEED. Optical absorption measurements indicated the onset of band-to-band transitions at an energy of approximately 6 eV. Finally, C-V testing showed that the films were insulating.
Fabrication of Ta2O5 Thin Films by Anodic Oxidation of Tantalum Nitride and Tantalum Silicide: Growing Mechanisms, Electrical Characterization and ULSI M-I-M Capacitor Performances
Authors: Dueñas S. , Castán H. , Barbolla J. , Kola R.R. , Sullivan P.A. 
Published: April 2011

ABSTRACTIn this work we report on tantalum oxide fabricated by anodic oxidation of tantalum nitride and tantalum silicide to be used as the dielectric of Metal-Insulator-Metal (MIM) capacitors. These films exhibit greatly improved leakage currents, breakdown voltage and very low defect density, thus allowing the fabrication of large area capacitors. Several counter and bottom electrodes have been used and compared. The effects of the different processing conditions (top-electrode metals, annealing conditions, bottom electrode stoichiometry and precursor) on the capacitor performances are extensively discussed throughout this work. The electrical behavior of the resulting high-density MIM capacitors has been extensively characterized. Finally, we propose a set of selection guides to select the more appropriate process parameter values and electrode materials for a given application of these capacitors.
H8Si8O12 Clusters on Si(100)-2×l and Gold: A Comparative Infrared Spectroscopic Study
Authors: Nicholson Kenneth T. , Biscotto Mark A. , Holl Mark M. Banaszak 
Published: April 2011

ABSTRACTReflection-absorption infrared data are presented for H8Si8O12 clusters chemisorbed to Si(100)-2×1 and evaporated gold surfaces. Peak assignments and the implications of the local symmetry imposed upon the cluster by the surface are discussed.
On the Influence of Boron-Interstitial Complexes on Transient Enhanced Diffusion
Authors: Stiebel D. , Pichler P. , Ryssel H. 
Published: April 2011

ABSTRACTWe present new experimental results on the transient enhanced diffusion (TED) of boron after ion implantation. The investigation is focussed on effects that influence TED of shallow profiles in the absence of {311}-defects. Under these conditions, TED is mainly determined by the formation of boron-interstitial complexes (BIC). In addition, effects from the proximity of the surface become more and more important. Insight into the behavior of the dopant atoms is obtained by the comparison with simulations.
Non Destructive Profile Measurements of Annealed Shallow Implants
Authors: Borden Peter , Niimeiier Regina , Lingel Karen 
Published: April 2011

ABSTRACTControlling the profile of shallow doped layers is critical for obtaining desired performance from deep sub-micron devices. An especially difficult challenge is measuring depth uniformity of the activated implant over the full area of a wafer.This paper demonstrates the capabilities of a new rapid, non-contact optical technique for measuring active doping depth of shallow implants. Employing a 2 Pim spot size, it provides a measurement of fine-scale spatial uniformity in dimensions approaching those of individual devices. By measuring multiple sites, it can rapidly characterize uniformity over large areas and edge-to-edge, without an edge exclusion zone.Data will be presented showing performance on layers varying in depth from 200 to 1200 Å. Edge-to-edge diameter scans on 8” wafers with le15, B11 implants at energies in the range of 200 to 2,000 eV and various RTA temperatures show radially symmetric uniformity patterns of depth and edge effects in the outermost centimeter. Measurements are validated based on correlation to spreading resistance profiles for a number of samples.
Temperature- and Time-Dependence of Boron-Enhanced Diffusion From Evaporated- and Ultra-Low Energy Ion-Implanted Layers
Authors: Agarwal Aditya , Gossmann H.-J. , Eaglesham D. J. 
Published: April 2011

ABSTRACTSilicon layers containing B in excess of a few atomic percent create a supersaturation of Si self-interstitials in the underlying Si, resulting in enhanced diffusion of B in the substrate (boron-enhanced diffusion, BED). The temperature- and time-dependence of BED is investigated here. Evaporated-boron as well as ultra-low energy 0.5-keV B-implanted layers were annealed at temperatures from 1100 to 800°C for times ranging from 3 to 3000s. Isochronal 10s anneals reveal that the BED effect increases with increasing temperature up to 1050°C and then decreases. In contrast, a simulation of interstitial generation via the kick-out mechanism predicts a decreasing dependence on increasing temperature leading to the conclusion that the kick-out mechanism is not the dominant source of excess interstitials responsible for BED. The diffusivity enhancements from the combined effects of BED and TED (transient-enhanced diffusion), measured in 2×105cm−2, 0.5-keV B-implanted samples, show a similar temperature dependence as seen for evaporated B, except that the maximum enhancement occurs at 1000°C. The temperature-dependent behavior of BED supports the hypothesis that the source of excess interstitials is the formation of a silicon boride phase in the high B concentration silicon layer.
Sub-30 nm abrupt P+ junction formation with Ge preamorphization and high energy Si Co-implantation
Authors: Lee K. L. , Zabel Ted , Kozlowski Paul M. , Viswanathan Raman , Chen Kai 
Published: April 2011

ABSTRACTExperiments have been caried out to form ultra-shallow (Xj <50nm) and abrupt (Xjs < 5nm/decade) P'junction for sub-50 nm CMOS devices using a combination of shallow implant, Ge preamorphization and high energy Si implant as an interstitial getter layer. Experimentally, it was observed that the Si getter layer, not only stopped the TED at the boron tail but also promoted enhanced diffusion close to the surface boron peak. These unique features have enabled the shallowest and sharpest box-like boron junction yet achieved by implant. With I kV BF2, Xj ∼ 23 nm, Xjs ∼ 48 A/decade, no Ge end of range damages and good dopant activation at the same time.The sheet resistance ρ − 1 kohm/sq is comparable to shallow BF2 + Ge and is better than the shallow BF 2 alone (ρ ∼ 2.38 kΩ/sq) or the shallow BF2 + Si implants (ρ ∼ 1.5 kohm/sq). Tests with device leakage test structures show that there is no additional junction leakage introduced by the Si getter layer.
In-Situ High Temperature Optical Microscopic Observations of Crystallization Mechanism in NdBa2Cu3Ox
Authors: Aswal D.K. , Shinmura M. , Hayakawa Y , Kumagawa M. 
Published: April 2011

ABSTRACTThe pseudo-binary NdBa2Cu3O-Ba3Cu10O13phase diagrams and the crystallization of NdBa2Cu3Ox have been in-situ observed using high-temperature optical microscopy in air and under three different reduced oxygen atmospheres namely, 1%, 0.1% and 0.0097% oxygen in argon. The liquidus line was found to become narrower both in composition and temperature with reducing oxygen content in the atmosphere. These results suggested that while in air NdBa2Cu3Ox can be crystallized from both high-temperature solution and peritectic melt; under reduced oxygen atmospheres the crystallization of NdBa2Cu3Ox is only possible from a peritectic melt. The in-situ observations of crystallization of NdBa2Cu3Ox from high-temperature solutions revealed that the growth mechanism changes from 3D via 2D layer-by-layer to continuos dendritic growth with increasing cooling rate. On the other hand, the NdBa2Cu3Ox crystallization from a peritectic melt involved two distinct steps (i) conversion of Nd4Ba2Cu2Ox into NdBa2Cu3Ox and (ii) nucleation and growth of NdBa2Cu3Ox The growth morphology in this case was independent of the cooling rate. This result and the direct observation of the dissolution of Nd4Ba2Cu2Ox into the liquid suggested that the solute diffusion is the rate-limiting factor.
In Situ Design of Experiments for A Reactive Ion Etching Process
Authors: Galarza Cecilia G. , Klimecky Pete , Khargonekar Pramod P. , Terry Fred L. 
Published: April 2011

ABSTRACTWe introduce a new procedure to perform a design of experiments (DOE) for plasma etching processes. In particular, we use in situ etch rate estimations to maximize the number of observable setpoints during a single run of the etching process. This procedure is applied to characterize the spatial uniformity of a plasma chamber used in the manufacturing of flat panel displays.
Real-Time Spectroscopic Ellipsometry Study of the Thermal Cleaning Process for Silicon Epitaxial Growth by UHV-CVD
Authors: Nozawa K. , Katayama K. , Kanzawa Y. , Sugahara Q. , Saitoh T. , Kubo M. 
Published: April 2011

ABSTRACTReal-time spectroscopic ellipsometry (RTSE) method was applied to study thermal cleaning process of silicon surfaces for epitaxial growth by ultra-high vacuum chemical vapor deposition (UHV-CVD). For the first time, in-situ observation of oxide decomposition process under Si2H6 ambience was carried out. The substrates with thin oxide formed by wet chemical treatment were heated up by infrared heater under UHV or under Si2H6 ambience in an UHV-CVD chamber and the oxide decomposition processes were observed by RTSE. Ellipsometric parameters Psi and Delta increase with the progress of oxide decomposition process and become constant with the completion of the decomposition. It was found that the oxide decomposition process consists of two phases and rate-determing processes are different in each phase. It was also found that Si2H6 lowers the activation energies of oxide decomposition process in each phase.
In-Situ Spectroscopic Ellipsometry and Optical Emission Studies of CF4/O2 Plasma Etching of Silicon Nitride
Authors: Parent T. , Tie J. , Madhukar A. 
Published: April 2011

ABSTRACTElectron cyclotron resonance (ECR) CF4/ 02 plasma etching of silicon nitride (SixNy) deposited by plasma enhanced chemical vapor deposition (PECVD) has been examined in-situ by means of spectroscopic ellipsometry (SE) and optical emission (OE). The observed real-time etchrate and the relative intensity of emission of atomic fluorine at 703.7 nm are measured simultaneously and both are found to change with time during the etch in a reproducible manner. The evolution of the real-time etch rate and the fluorine emission intensity depends on the machine input settings and the extent to which the chamber has been exposed to CF4/ 02 plasma prior to sample introduction. In general the initial 10 to 40 seconds of etching reveal a rapid increase in the etch rate, the remainder of the etch exhibiting an etch rate which typically increases gradually until the etch is stopped. This variation in etch behavior with time during the etch process complicates the task of precisely and reliably etching ultrathin (< 50 nm) films, necessitating real-time control based upon in-situ sensors, the end objective of this work. The dependence of the evolution of the SixNy etch rate on microwave power, chamber pressure, and gas in-flow rate is presented and the implications of these dependencies on the implementation of real-time feedback control are discussed.
Atomic Interdiffusion in Amorphous Silicon and Germanium
Authors: Persans P. D. , Ruppert A. F. 
Published: April 2011

AbstractWe present measurements of interdiffusion in amorphous silicon/amorphous germanium compositional multilayer structures using Raman scattering and optical absorption spectroscopies. We find that interdiffusion coefficient D* can be described by D* = Do exp (−ED/kT) with ED = 3.3 eV and Do = 104 cm2s−1. The high value of ED suggests that the diffusion process is substitutional.
Undercooling of Liquid Germanium
Authors: Devaud G. , Turnbull D. 
Published: April 2011

AbstractSmall liquid germanium (ℓ-Ge) droplets (0.3–0.5mm diameter) have been undercooled in a B2O3 flux a maximum of 415 ± 20°C below Tm before recalescence. Although the droplets undercooled to temperatures well below the temperature expected for metastable equilibrium with amorphous Ge, Taℓ, the solidified structures were always polycrystalline. There was no evidence of a continuous liquid-to-amorphous transition at or below Taℓ. The nucleation frequency was calculated to be ˜8 × 106 /cm 3-sec at the maximum undercooling. This should be an upper limit to the homogeneous nucleation frequency of the crystal phase since we did not establish that the nucleation was homogeneous in our experiments. However, this limiting I for Ge indicates that homogeneous nucleation of the crystal or amorphous phase would not become appreciable in nsec laser pulsing experiments until ℓ-Ge is undercooled to well below Taℓ. The structure of solidified Ge and Ge/Sn alloy droplets indicates that dendritic growth does not occur in Ge until the liquid is undercooled at least 300°C, and in Ge/Sn until the liquid is undercooled at least 250°C. Greater undercoolings lead to increased dendritic breakup, which results in grain refinement in the final structure.
Theoretical Studies of Dark Current of Quantum Dots
Authors: Chang Yia-Chung , Kuo David M. T. 
Published: April 2011

ABSTRACTA time evolution method is used to compute the electron escape time and dark current of a quantum dot under electric field. We found that for quantum dots with just one bound state, the ground state wave function can be well described by the product of a 2D confined wave function in the x, y plane and a 1D confined wave function in the z direction with an effective quantum well potential. A comparison of phase-shift analysis and the full time-dependent calculation is presented. Good agreement between the two in the large time scale is found, but discrepancy exists in the small time scale. Our study shows that the electron escape rate (which determines dark current) of quantum dots is much lower than that of quantum wells with the same bound-to-continuum transition energy.
Optical Phonons in CdS Nanocrystals: Effects of Size, Shape and Packing Density
Authors: Rolo A.G. , Vasilevskiy M.I. , Gomes M.J.M. , Vikhrova O.V. , Rakovich Yu.P. , Artemyev M.V. 
Published: April 2011

ABSTRACTOptical vibrations confined in CdS nanocrystals (embedded in a glass film or forming a close-packed film with some organic-molecule links between them) have been studied experimentally, by means of FIR and Raman spectroscopies, and theoretically. The asymmetric Raman lineshape can be modelled considering resonant and non-resonant scattering on spherical modes with 1=0 (those with n>l are responsible for the low-frequency wing). A phonon-related dielectric response of the nanocrystal composites has been studied by measuring FIR reflectivity and transmission spectra. The theoretical consideration consists of the (i) calculation of the single-particle polarisability due to the confined 1=1 modes and (ii) including the dipole-dipole interaction between the particles. We show that, for the smallest particles, the FIR response has a bimodal structure, which disappears as the nanocrystal size increases. However, the experimentally observed bulk-CdS-like reflection band at 230–300 cm−1 is too broad and can not be explained by the model. Only making further assumptions, namely, of a fractal structure of the nanocrystal composites, enables us to fit well the experimental FIR spectra.
Line Shape in Resonance Raman Scattering from Silicon Quantum Dots
Authors: Soni R.K. , Fonseca L.F. , Resto O. , Weisz S.Z. , Tripathy S. 
Published: April 2011

ABSTRACTWe have carried out a resonance Raman study of line-shape in silicon quantum dots synthesized on a quartz substrate by co-sputtering bulk Si and Si02. Optical transmission measurements are used to evaluate dot size distribution. The size distribution shows peaks around 1.0 and 1.4 nm. The Si dots exhibit photoluminescence in the visible region, which shifts to higher energy with decreasing size. The size dependence of Raman scattering shows phonon softening and increasing asymmetrical broadening for small dots (< 2nm). The observed spectra are compared with calculations considering electron-hole interactions at a quasi-direct gap of a spherical quantum dot.
Wafer Bonding Involving Complex Oxides
Authors: Alexe M. , Kopperschmidt P. , Gösele U. , Tong Qin-Yi , Huang Li-Juan 
Published: April 2011

AbstractThe present paper proposes a simple method which may be able to provide true single-crystal films of complex oxides on large substrates including semiconductors like silicon or gallium arsenide. The method describes a layer transfer process using layer splitting by hydrogen implantation and direct wafer bonding (DWB) to obtain single-crystal oxide films on different substrates. Alternatively, a fabrication process of ferroelectric-semiconductor heterostructures based on direct wafer bonding and layer transfer is also described. This process is an alternative method to the direct deposition of oxides films (ferroelectric, high-k) on silicon and allows fabrication of metal oxide-silicon heterostructures with an interface having a good structural quality as well as a low trap density.