bluuebunny/crossref_metadata_2025_split huggingface dataset:
Broadband Determination of Microwave Permittivity and Loss in Tunable Dielectric Thin Film Materials
Authors: Booth James C. , Vale Leila R. , Ono Ronald H. 
Published: April 2011

AbstractWe demonstrate a new method for determining the frequency-dependent dielectric properties of thin-film materials at microwave frequencies using coplanar waveguide (CPW) transmission line measurements. The technique makes use of the complex propagation constant determined from multiline thru-reflect-line (TRL) calibrations for CPW transmission lines to determine the distributed capacitance and conductance per unit length. By analyzing data from CPW transmission lines of different geometries, we are able to determine the complex permittivity of the dielectric thin film under study as a function of frequency from 1 to 40 GHz. By performing these measurements under an applied bias voltage, we are able in addition to determine the tuning and figure of merit that are of interest for voltage-tunable dielectric materials over the frequency range 1 to 26.5 GHz. We demonstrate this technique with measurements of the permittivity, loss tangent, tuning, and figure of merit for a 0.4 µm film of Ba0.5Sr0.5TiO3 at room temperature.
What Does Self-Diffusion Tell Us about Ultra Shallow Junctions?
Authors: Ural Ant , Koh Serene , Griffin P. B. , Plummer J. D. 
Published: April 2011

AbstractUnderstanding the coupling between native point defects and dopants at high concentrations in silicon will be key to ultra shallow junction formation in silicon technology. Other effects, such as transient enhanced diffusion (TED) will become less important. In this paper, we first describe how thermodynamic properties of the two native point defects in silicon, namely vacancies and self-interstitials, have been obtained by studying self-diffusion in isotopically enriched structures. We then discuss what this tells us about dopant diffusion. In particular, we show that the diffusion of high concentration shallow dopant profiles is determined by the competition between the flux of mobile dopants and those of the native point defects. These fluxes are proportional to the interstitial or vacancy components of dopant and self-diffusion, respectively. This is why understanding the microscopic mechanisms of silicon self-diffusion is important in predicting and modeling the diffusion of ultra shallow dopant profiles. As an example, we show experimental data and simulation fits of how these coupling effects play a role in the annealing of shallow BF2 ion implantation profiles. We conclude that relatively low temperature furnace cycles following high temperature rapid thermal anneals (RTA) have a significant effect on the minimum junction depth that can be achieved.
Ion Implantation Effect on Dislocation Propagation in Pseudomorphically Strained P/P+ Silicon
Authors: Feichtinger Petra , Poust Ben , Fukuto Hiroaki , Sandhu Rajinder , Goorsky Mark S. , Oster Dwain , Rickborn Steve F. , Moreland Jim 
Published: April 2011

AbstractWe studied damage evolution and the influence on defect interactions as a function of Si self implantation dose in p/p+ silicon wafers. Highly boron doped 150 mm diameter silicon substrate wafers with a 2.5 μm thick nominally un-doped epitaxial layer (p/p+) were employed. Due to the misfit strain, misfit dislocations formed during the epitaxial growth process around the wafer edges. This localized dislocation distribution was utilized to study the role of the implant on both the nucleation and growth of the misfit dislocation segments. Triple axis x-ray diffraction was used to determine changes to the strain in the layer due to both the implant and to subsequent annealing. Double axis x-ray topography combined with rapid thermal annealing was used to measure the nucleation and extension of the misfit dislocation segments after annealing. For the lower implantation dose (1012 cm−2) samples, the velocity of dislocations was reduced measurably and the density of newly formed misfit dislocations also decreased significantly relative to regions that received no ion implantation. A higher implantation dose reduced the nucleation and glide velocity further such that neither glide nor nucleation of new segments was detected. SIMS measurements confirmed that the interfacial lattice parameter grading was not appreciably different after an anneal step for the lower implant dose sample, but was measurable for the higher dose sample. In the latter case, transient point defect enhanced diffusion of boron was responsible for the grading. However, the lack of grading in the low dose sample indicates that interfacial grading did not significantly impede dislocation kinetics. This comparison indicates that it is the excess point defects that are produced during implantation that retard both the nucleation and extension of misfit dislocation segments.
The Impact of Point Defects on Stress-Induced Dislocation Generation in Silicon
Authors: Loiko Konstantin V. , Nallapati Giri , Jarreau Keith M. , Ekbote Shashank S. , Hensley Roy A. , Simpson Dale , Harrington Thomas E. , Frensley William R. , Peidous Igor V. 
Published: April 2011

AbstractFactors responsible for the onset of dislocation generation in the fields of localized high stresses have been studied in LOCOS-isolated test structures by means of preferential etching, junction leakage analysis, and computer simulation. A strong correlation between densities of stacking faults and dislocations was observed in the experiments. Defect distributions also correlated to leakage currents. 2D simulations of stresses, interstitial injection, and stacking fault growth during field oxidation showed that maximum resolved shear stress in the structures did not exceed the critical level for dislocation generation and that the agglomeration of silicon interstitial atoms did not play a notable role in dislocation nucleation. Dislocation and stacking fault formation was attributed to surface mechanical damage introduced during plasma processing.
Phosphorus / Silicon Interstitial Annealing After Ion Implantation
Authors: Keys P. H. , Brindos R. , Krishnamoorthy V. , Puga-Lambers M. , Jones K. S. , Law M. E. 
Published: April 2011

AbstractThe release of interstitials from extended defects after ion implantation acts as a driving force behind transient enhanced diffusion (TED). Implantation of Si+ ions into regions of phosphorus-doped silicon provides experimental insight into the interaction of silicon interstitials and dopant atoms during primary damage annealing. The presence of phosphorus influences the morphology of secondary defects during initial nucleation. Transmission electron microscopy (TEM) is used to differentiate between defect types and quantify the interstitials trapped in extended defects. This analysis reveals that phosphorus results in a reduction of interstitials trapped in observable extended defects. The interstitial flux released from the implanted region is also affected by the phosphorus doping. This phenomenon is closely studied using secondary ion mass spectrometry (SIMS) to monitor diffusion enhancements of dopant layers. Shifts in diffused dopant profiles are correlated with the different morphologies of the extended defects and the decay of the silicon interstitial supersaturation. This correlation is used to understand the interaction of excess silicon interstitials with phosphorus atoms.
Molybdenum as a Gate Electrode for Deep Sub-Micron CMOS Technology
Authors: Ranade Pushkar , Yeo Yee-Chia , Lu Qiang , Takeuchi Hideki , King Tsu-Jae , Hu Chenming 
Published: April 2011

ABSTRACTMolybdenum has several properties that make it attractive as a CMOS gate electrode material. The high melting point (∼2610°C) and low coefficient of thermal expansion (5×10−6/°C, at 20 °C) are well suited to withstand the thermal processing budgets normally encountered in a CMOS fabrication process. Mo is among the most conductive refractory metals and provides a significant reduction in gate resistance as compared with doped polysilicon. Mo is also stable in contact with SiO2 at elevated temperatures. In order to minimize short-channel effects in bulk CMOS devices, the gate electrodes must have work functions that correspond to Ec (NMOS) and Ev (PMOS) in Si. This would normally require the use of two metals with work functions differing by about 1V on the same wafer and introduce complexities associated with selective deposition and/or etching. In this paper, the dependence of the work function of Mo on deposition and annealing conditions is investigated. Preliminary results indicate that the work function of Mo can be varied over the range of 4.0-5.0V by a combination of suitable post-deposition implantation and annealing schemes. Mo is thus a promising candidate to replace polysilicon gates in deep sub-micron CMOS technology. Processing sequences which might allow the work function of Mo to be stabilized on either end of the Si energy band gap are explored.
Investigation on C54 nucleation and growth by micro-Raman imaging
Authors: Privitera Stefania , Meinardi Francesco , Quilici Simona , Via Francesco La , Spinella Corrado , Grimaldi Maria Grazia , Rimini Emanuele 
Published: April 2011

ABSTRACTThe processes of nucleation and growth of the C54 TiSi2 phase into the C49 phase in thin films have been studied by electrical measurements and micro-Raman spectroscopy. The Raman spectra have been acquired scanning large silicide areas (100×50 μm2) in step of 0.5 μm. Images showing the evolution of the C54 grains during the transition have been obtained for temperatures between 680 and 720 °C and the transformed fraction, the density and the size distribution of the C54 grains have been measured as a function of the temperature and the annealing time. The activation energies for the nucleation rate and the growth velocity have been determined obtaining values of 4.9 ± 0.7 eV and 4.5 ± 0.9 eV, respectively.
Performance of Polishing Slurries containing Silica Particles grown by Sol-Gel Method
Authors: Bae Sun Hyuk , So Jae-Hyun , Yang Seung-Man , Kim Do Hyun 
Published: April 2011

ABSTRACTSilica slurry used as abrasives in wafer polishing process is made by dispersing silica particles in an alkali solution. Since commercially available colloidal or fumed silica particles need some modifications to be directly used as abrasive slurry due to their small sizes, irregular shapes or broad size distribution, we have prepared silica abrasives by particle growth of fumed silica or colloidal silica as seeds by sol-gel method. Silica slurries prepared by this step-wise growth from commercial seeds were tested using one-armed polisher for the comparison with commercial slurries and showed the performance comparable to commercial slurries. Microstructures of polishing slurries were investigated using transmission electron microscopy and ARES rheometer. From the result, stability of the slurry was found to be more important than the primary particle sizes for the polishing performance.
Superparamagnetic Behavior of Granular Co-C Films Consisting of Nanocrystalline Cobalt Encapsulated in Carbon
Authors: Wang Hao , Wong S.P. , Cheung W.Y. , Ke N. , Chiah M.F. , Wen G.H. , Zhang X.X. 
Published: April 2011

ABSTRACTNanocomposite Co-C thin films of about 15 nm thick were prepared by pulsed filtered vacuum arc deposition. The films were characterized by x-ray photoelectron spectroscopy, non-Rutherford backscattering spectrometry, x-ray diffraction, magnetic force microscopy and magnetic measurements. The as-deposited films were amorphous. After annealing at 350°C for one hour in vacuum (< 10−3 Pa), the films were found to consist of nanocrystalline Co grains encapsulated in carbon. The superparamagnetism of the annealed Co36C64 film was demonstrated by the measurement of DC susceptibility and magnetic hysteresis using a SQUID magnetometer. The superparamagnetic relaxation blocking temperature was marked to be about 12K by the peak of the zero-field-cooled magnetization under a field of 100 Oe. The magnetic properties of these annealed granular Co-C films transform from superparamagnetism to ferromagnetism when the Co concentration increases.
Manufacturability of Gmr Heads: 10Gb/in2 and Beyond
Authors: Sahu S. , Chen Jian , Talghader V. , Cool S. , Mao S. 
Published: April 2011

ABSTRACTConsistency of spin-valve stack deposition, both wafer-to-wafer and within a wafer, is key to the manufacturability of GMR heads. For typical GMR heads, film thicknesses are now in the range of 5Å-150Å and process control is becoming a challenge.This paper discusses the importance of characterizing the thickness and uniformity of each material in the spin-valve stack within the context of single layer sheet films. For this study, single layer sheet films and full multilayer spin-valve stacks were deposited in a multi-target cluster tool. The sheet resistance and thickness of the single layer sheet films were measured using a 4-point probe and ellipsometry, respectively. Results were then correlated to the sheet resistance and magnetic performance (i.e., GMR ratio, exchange field, and magneto-static coupling field) of the full spin-valve stacks with a synthetic antiferromagnet as the pinned layer. The 1σ < 2% uniformity, wafer-to-wafer and within wafer, realized for the full stacks is a strong indicator of a manufacturable process.Model calculations of the sheet resistance and GMR were carried out to provide theoretical understanding of the film thickness dependence. The calculated results are well correlated with the experimental measurements. The model is based on band structures and implicitly includes the momentum-dependent reflection and transmission coefficients at the interfaces.Results from both experiments and calculations show that process control and repeatability (both within a wafer and from wafer to wafer) are crucial to the spin-valve manufacturability, offering a critical challenge to the disc drive industry as it heads into the next generation of GMR heads.
Residual Stresses and Magnetoelastic Coupling in Ultrathin Fe Films Deposited on GaAs(001)
Authors: Gergaud P. , Lallaizon C. , Putero M. , Lépine B. , Thomas O. , Guivarc'h A. 
Published: April 2011

ABSTRACTThe growing interest in the behavior of magnetic thin films on semiconductor substrates is due in part to their potential application in spin-sensitive heterostructure devices. High-quality epitaxial Fe(001) thin films can be grown on GaAs(001) substrates because of the small lattice parameter mismatch (−1.4%). Magnetic measurements performed on Fe films thinner than 3 nm have shown that such films exhibit an in-plane uniaxial magnetic anisotropy although an ideal bcc Fe(001) film should have fourfold symmetry. The source of this uniaxial component remains an open question and one of the mechanisms which may contribute to this is the epitaxial strain, through magnetoelastic coupling. Very small strains anisotropies are able to modify the magnetic anisotropy of iron thin films. Moreover the sign and magnitude of the magnetoelastic coupling seem to depend on the film thickness or film strain [1]. In this study, the strain tensor components in two Fe thin films (1.7 and 3.0 nm thick) has been measured by XRD. The magnetic free energy has been derived, using the strain tensor components.
Work Function Study of Polycrystalline Metals using a UHV Scanning Kelvin Probe
Authors: Petermann U. , Baikie I.D. , Lägel B. , Dirscherl K.M. 
Published: April 2011

ABSTRACTWe have undertaken a study of high work function (φ) surfaces as part of an ongoing project searching for efficient target materials for use in Hyperthermal Surface Ionisation (HSI), a new mass spectroscopy ionisation technique. HSI relies on high work function surfaces for the production of positive ions. Polycrystalline metals as Re, W, Mo and Pt are particularly interesting materials in this respect as oxidation substantially increases their φ. We present and discuss the following experimental evidence: a) the magnitude and sign of φ changes in terms of adsorbate induced dipoles, b) the effect of molecular hydrogen exposure on the clean surface, and c) the effect of subsequent oxygen exposure.Using a novel UHV Scanning Kelvin Probe we have followed the oxidation kinetics of polycrystalline metals at different temperatures and examined the effects of oxidation, flash annealing and sputter-anneal cleaning cycles via high-resolution φ topographies. Our results indicate in particular Re as a suitable HSI target material exhibiting a φ increase of 1050 meV at 300 K increasing to 2050 meV at 900 K. Sputter-cleaned surfaces exhibit a dramatic change in the second oxidation phase.We have also examined φ changes associated with N2O and CO2 on Tungsten and Molybdenum. We observe that atomic oxygen gives similar results to O2 but has a much lower initial sticking coefficient. We report that CO2 actually lowers the φ for substrate temperatures under 650 K, the peak work function changes occurs at 850 K and is approximately 1/3 the height of the O2 or O peak.
Observation of Long-Range Orientational Ordering in Metal Films Evaporated at Oblique Incidence onto Glass
Authors: Everitt David L. , Zhu X. D. , Miller William J. , Abbott Nicholas L. 
Published: April 2011

ABSTRACTWe studied long-range orientational ordering in polycrystalline Au films (10 nm - 30 nm) that are evaporated at oblique incidence onto a glass substrate at room temperature. By measuring the averaged optical second-harmonic response from the films over a 6-mm diameter region, we observed a transition from the expected in-plane mirror symmetry at 10 nm to a surprising three-fold in-plane rotational symmetry at 30 nm. X-ray pole figure analysis performed on these films showed the strong <111> fiber texture typical of fcc films, but with a restricted, three-fold symmetric, distribution of crystallite orientations about the fiber axis.
Alignment of InAs Quantum Dots on GaAs Using the Manipulation of Strain Fields
Authors: Kim Kwang Moo , Park Young Ju , Park Young Min , Nah Jong Bum , Hyon Chan Kyeong , Kim Eun Kyu , Park Jung Ho 
Published: April 2011

ABSTRACTWe fabricated InAs self-assembled quantum dots (QDs) on strained layer using molecular beam epitaxy. The strained layer consisted of InAs/GaAs superlattice(SL) and GaAs barrier layer on (001) GaAs substrate. Through controlling thickness of the strained layer, we formed two-dimensional alignments of QDs on misfit dislocation arrays along <110> directions made by strained layer. The increase of the strained layer thickness resulted in a stronger alignment of QDs, which were observed by atomic force microscopy studies. The aligned QDs were confirmed to confine carriers well and have different size distributions by photoluminescence measurement.
On Kinetically vs. Energetically Driven Growth Instabilities in Solid and Vapor Phase Epitaxy
Authors: Aziz Michael J. 
Published: April 2011

ABSTRACTA stress-induced kinetically-driven morphological instability is of general applicability to driven systems. The effect of stress on the reaction mobility for incorporation into the growing solid couples to stress variations along a perturbed planar growth front, resulting in amplification or decay of the perturbation depending on the sign of the stress. Experimentally we studied a model system in which stress is applied externally to a chemically pure substance, permitting us to isolate the effect of strain from any possible effects of composition, and found that the new kinetically-driven effect dominates the behavior for solid phase epitaxial growth (SPEG) of Si(001). A linear stability analysis of a sinusoidally perturbed planar growth front, incorporating both the kinetically and the energetically driven effects, has been performed. Stability maps are developed, indicating parameter ranges under which the morphological evolution is dominated by the energetically-driven instability, the kinetically-driven instability, and the kinetically-driven stabilization. Numerical values of the key dimensionless parameters for SPEG and for SiGe/Si(001) Molecular Beam Epitaxy (MBE) are very similar in cases where they are known, indicating that the kinetically-driven effect may be important in determining morphological evolution related to quantum dot formation in MBE as well
Structure and Optical Properties of Si/InAs/Si Layers Grown by MBE on Si Substrate at Different Temperatures
Authors: Zakharov N.D. , Werner P. , Gösele U. , Heitz R. , Bimberg D. , Ledentsov N.N. , Ustinov V.M. , Volovik B.V. , Alferov ZH.I. , Polyakov N.K. , Petrov V.N. , Egorov V.A. , Cirlin G.E. 
Published: April 2011

ABSTRACTEpitaxial Si/InAs/Si heterostructure grown on (001) Si substrate by molecular beam epitaxy (MBE) and annealed at 800°C, and 880°C were investigated by High Resolution Transmission Electron Microscopy (HRTEM). Extensive interdiffusion at 800°C leads to the formation of an InAs solid solution as well as InAs-enriched regions with extensions of ∼6nm, which exhibit two kinds of ordering. The ordering of InAs molecules occurred, respectively, in {110} planes inclined and parallel to the [001] growth direction. It is attributed to the energy gain from the reduced number of mixed Si-As and Si-In bonds. The sample grown at 800°C shows photoluminescence in the 1.3.µm region, which is tentatively attributed to the recombination of excitons localised in the ordered regions
Metalorganic Molecular Beam Epitaxy of Magnesium Oxide on Silicon
Authors: Niu F. , Hoerman B.H. , Wessels B.W. 
Published: April 2011

ABSTRACTEpitaxial cubic MgO thin films were deposited on single crystal Si (001) substrates by metalorganic molecular beam epitaxy (MOMBE) using the solid precursor magnesium acetylacetonate as the source and an RF excited oxygen plasma as the oxidant. The growth process involved initial formation of an epitaxial β-SiC interlayer followed by direct deposition of a MgO overlayer. The film structure was characterized by X-ray diffraction as well as conventional and high-resolution transmission electron microscopy. Both the MgO overlayer and β-SiC interlayer had an epitaxial relationship such that MgO (001) (or SiC (001)) // Si (001) and MgO [110] (or SiC [110])// Si [110]. No evidence of an amorphous layer was observed at either the MgO/SiC or SiC/Si interface. Dielectric properties of the epitaxial MgO thin films on Si (001) were evaluated from capacitance-voltage (C-V) characteristic of metal-oxide-semiconductor (MOS) structures. The C-V measurements indicated an interface trap density at midgap as low as 1011 to 1012 cm−2 eV−1 and fixed oxide charge of the order of 1011/ cm2, respectively. These results indicate that epitaxial MgO deposited by MOMBE has potential as a gate insulator.
Real Time Observations of Dislocation-Mediated Plasticity in the Epitaxial AI (011)/Si(100) Thin Film System
Authors: Stach Eric A. , Dahmen U. , Nix W.D. 
Published: April 2011

ABSTRACTDespite numerous theoretical and experimental studies of strain relaxation in metal films on silicon substrates, the exact mechanisms by which dislocations mediate plasticity in these structures are not well understood. To elucidate these mechanisms, we present results from in-situ transmission electron microscopy annealing of thin aluminum films grown on Si (100). As a model system, we have chosen to focus on aluminum films which contain two (011) epitaxial variants with respect to the silicon substrate. In this paper we discuss our observations of the glide and climb behavior of dislocations in these structures during thermal cycling. These observations give qualitative insight into the mechanisms by which dislocation motion accommodates thermally induced strains in thin metal films.