bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integration Challenges for Advanced Salicide Processes and their Impact on CMOS Device Performance
Authors: Wieczorek K. , Horstmann M. , Engelmann H.-J. , Dittmar K. , Blum W. , Sultan A. , Besser P. , Frenkel A. 
Published: April 2011

ABSTRACTCoSi2 has emerged as the silicide of choice for 0.18μm CMOS technologies and below. Robustness and scaling-performance of an integrated CoSi2-module, however, is shown to critically depend upon careful optimization of each individual process-step. The impact of surface-preparation, capping layer, initial Co-thickness and thermal processing will be discussed. The scalability of an optimized process meeting all major requirements for application to ULSI devices is demonstrated for gate-length down to 60nm.
Effect of a thin Ta layer on the C49-C54 transition.
Authors: Via F. La , Mammoliti F. , Grimaldi M.G. , Quilici S. , Meinardi F. 
Published: April 2011

ABSTRACTThe effect of a thin Ta layer at the Ti/Si interface on the kinetic of the C49-C54 transition will be shown in detail. The transformation kinetic has been monitored by in situ sheet resistance measurements that, coupled to structural characterisation, allowed to evidence the presence of an intermediate phase before the C54 formation. The temperature of the C54 phase formation decreases with a Ta concentration of 4.5·1015 cm−2 and μ-Raman images of partially transformed samples indicates that the density of C54 grains in presence of Ta is about one order of magnitude higher with respect to pure Ti/Si samples.
Hot Wall Isothermal RTP for Gate Oxide Growth and Nitridation
Authors: Laser Allan , Ratliff Christopher , Yao Jack , Bailey Jeff , Passefort Jean-Claude , Vaughan Eric , Page Larry 
Published: April 2011

ABSTRACTA new system that incorporates many benefits of large batch furnaces (high quality films, growth of wet and dry oxides, chlorine capability, and low cost) into a single wafer processing module has been developed at SVG Thermal Systems. The problems associated with wafer temperature measurement and control in traditional lamp based RTP systems are avoided by utilizing a hot wall isothermal processing chamber. Unique fixturing is used to minimize thermal stress on the wafer during ramping. High quality gate oxides ranging in thickness from 20Å to 40Å have been grown in this system using both wet and dry oxidation ambients, with and without chlorine. Thin oxides grown in dry oxygen had 1-sigma uniformities in the range of 0.72-0.95%, while oxides grown in oxygen/HCl (1-3%) had uniformities of 0.80%. Steam grown oxides demonstrated growth rates of 100Å/min at 900°C and uniformities of 0.62%. Dry oxides annealed in NO and N2O had peak nitrogen incorporation levels ranging from 0.5 to 5.1 atomic percent depending on anneal ambient, temperature and time.
On the Template Mechanism of Enhanced C54-TiSi2 Formation
Authors: Kappius L. , Tung R. T. 
Published: April 2011

ABSTRACTThe enhanced formation of the C54-TiSi2 phase by the addition of small amounts of refractory metal (Tm = Mo, Ta, Nb,..) has often been ascribed to a template mechanism from the C40 TixRm1−xSi2 or the (Ti,Rm)5Si3 phase. Due to lattice matching conditions, the presence of either of these phases is thought to lower the interface energies with certain orientations of the C54-TiSi2 grain and, thereby, possibly lower the nucleation barrier of the C54-TiSi2 phase. These proposed template mechanisms are specifically tested in the present work through a study of the nucleation of TiSi2 phase(s) in contact with a pre-existing C40 Ti0.4Mo0.6Si2 or Ti5Si3 layer. No identifiable enhancement in the C54-TiSi2 nucleation was observed which could be attributed to templates. Instead, the nucleation temperature of the C54-TiSi2 phase appeared to be correlated with the grain size of the C49-TiSi2 layer, independent of whether Rm was present. These results are suggestive that the primary mechanism for the enhanced formation of the C54 phase by refractory metals is a reduction in the grain size of the C49 TiSi2phase, likely due to altered kinetics.
Modeling on Mechanical Properties of Polishing Pads in CMP Process
Authors: Nishioka Takeshi , Iwami Satoko , Kawakami Takashi , Tateyama Yoshikuni , Ohtani Hiroshi , Miyashita Naoto 
Published: April 2011

ABSTRACTChemical mechanical polishing is an essential process for achieving a high degree of planarization. The planarity after CMP sensitively depends on pattern scales, pattern densities and mechanical properties of polishing pads. In order to simulate the topography after CMP, a numerical model for the polishing pad is proposed. In this model, the surface roughness layer of the polishing pad is assumed as a flat soft layer. The distribution of the contact pressure between the patterned wafer and the polishing pad is calculated with finite element method, and the pattern topography is modified based on the pressure dependency of the polishing rate. The iterations of the contact pressure analyses and the topography modifications give the progress of the polishing process numerically. The model is applied to oxide CMP process with silica slurry and stacked pad of polyurethane and non-woven fabric. The compressive elastic moduli of polyurethane layer and non-woven fabric layer are measured dynamically. The elastic modulus of the soft layer is treated as a fitting parameter between the experimental results and the numerical model. The models with the elastic modulus of 10 MPa for the soft layer show good agreements with the experimental results in both of a short range, where the compressive deformation of the pad is dominant, and a long range, where the bending deformation is dominant. Static measurements for the surface elasticity of the polyurethane layer also give a good agreement with the model. The proposed pad model should be useful for the topography simulation, and it also guides the development of new polishing pads.
On Extreme Density of Data Storage in Patterned Magnetic Media
Authors: Meilikhov E. , Aronzon B. , Gurovich B. , Kuleshova E. 
Published: April 2011

ABSTRACTA patterned magnetic medium is the next step to significantly increasing data storage density. To attain extreme density, it is necessary to deal with the smallest granules (each storing a bit of information) admissible from the physical point of view. It is well known that the volume of such granules, and their aspect ratio, have to be large enough to prevent thermally activated magnetization relaxation. However, these requirements are not exhaustive. A patterned recording medium is a set of closely-spaced, aligned magnetic granules, with the random (“up” and “down”) orientations of granules' magnetic moments. Though the exchange interactions between the granules may be neglected, there are long-range intergranular dipole-dipole interactions (DDI) which lead to significant lowering of activation barrier preventing thermal relaxation. Those interactions limit the acceptable density of ferromagnetic granules, and hence, reduce the extreme density of data storage. Our numerical calculations estimate the negative role of DDI for the particular case of a two-dimensional set of ellipsoidal magnetic granules and allow us to determine the extreme density of data storage.
Grain Size Relationships between the Magnetic Layer and the Underlayers in CoCrPtTa Recording Media
Authors: Ma Kai , Sinclair Robert , Bertero Gerardo , Cao Wei 
Published: April 2011

ABSTRACTThis article presents a transmission electron microscopic (TEM) investigation of the relationship between the magnetic and underlayer grain sizes in CoCrPtTa/CrMo longitudinal magnetic recording media. A great deal of effort has been expended on decreasing the underlayer grain size in order to decrease that of the magnetic layer. However, our results show that the two grain sizes may not always correlate. When the underlayer (CrMo) grains are sufficiently small, the magnetic layer (CoCrPtTa) grain size does not necessarily decrease with further underlayer grain size reduction. By carefully controlling the processing conditions, CrMo grain sizes were made to vary from 16nm down to 10nm. However, the corresponding CoCrPtTa grain sizes remained nearly the same. As the underlayer grain size decreased, the ratio of magnetic to underlayer grain size increased from 0.9 to 1.4.
Magnetotransport and Magnetic Properties of La0.7MnO3−δ and Pr0.65Ba0.05Ca0.3MnO3−δ Superlattices
Authors: Pietambaram Srinivas V. , Kumar D. , Singh Rajiv K. , Lee C. B. 
Published: April 2011

ABSTRACTIn an effort to achieve high magnetoresistance ratios at high temperature and low fields, we have fabricated superlattice structures consisting of La0.7MnO3−δ (LMO) and Pr0.65Ba0.05Ca0.3MnO3−δ (PBCMO) systems where La0.7MnO3−δ is believed to act as a ferromagnetic biasing source to Pr0.65Ba0.05Ca0.3MnO3−Δ. LMO and PBCMO individually transform to ferromagnetic states at 240 K and 60 K respectively. A series of samples, in which the thickness of La0.7MnO3−δ is fixed and that of Pr0.65Ba0.05Ca0.3MnO3−δ varied from 1 to 8 unit cells, have been grown in situ on (100) LaAlO3 substrates using a pulsed laser deposition technique. Microstructural characterization carried out on these films show the presence of characteristic intense satellite peaks indicating the chemical modulation of the superlattice structure. The insulator-to-metal transition and the MR ratio, defined as [R(0)-R(H)/R(H)], where R(0) and R(H) are resistances in zero and applied fields, is found to vary with the number of unit cells. The samples with 1, 2, 5 and 8 unit cells of Pr0.65Ba0.05Ca0.3MnO3−δ show a transition temperature of 240 K, 230 K, 150 K and 160 K and MR ratio of 540%, 592%, 3150% and 2875 % respectively. We have observed an enhancement of magnetoresistance ratio in case of superlattices with thickness of PBCMO greater than 5 unit cells. We attribute this enhancement to a ferromagnetic biasing provided by the LMO layers acting as a ferromagnetic film below its transition temperature.
Chemical Ordering and Microstructure of FePd Thin Films with perpendicular Magnetic Anisotropy
Authors: B. Gilles , F.F. Xu , D. Halley , A. Marty , Y. Samson , G. Patrat 
Published: April 2011

ABSTRACTFePd(001) thin films have been grown by the molecular beam epitaxy (MBE) technique. At room temperature, these films are chemically disordered whereas at 350 °C a well ordered L10 structure is found with the c-axis oriented in the growth direction. By combining RHEED, STM and Auger measurements, it is suggested that ordering occurs at the growing surface by the development of bi-atomic steps of the ordered structure. We have put in evidence that the surfactant behavior of the Pd atoms is mainly involved in the ordering process and selects the single orientation of the c-axis. For intermediate temperatures between RT and 350 °C, TEM and X-rays have evidenced a pseudo-periodic arrangement of anti-phased domains having a columnar shape. The variation of the long-range order parameter is related to the average size of these ordered domains.
Electrical And Microscopic Investigation Of E-Gun Evaporated Titanium Thin Films
Authors: Hofmann Karl , Luysberg Martina , Spangenberg Bernd , Kurz Heinrich 
Published: April 2011

ABSTRACTThe deposition rate of titanium films plays a determining role for possible fabrication schemes of metallic SET structures. Depending on this rate the resistivities display a striking difference in their temperature dependence which is attributed to their different crystal structure as analyzed by transmission electron-beam microscopy. In addition a sharp rise in resistivity occurs below a critical thickness in films deposited at slow rates. This sharp increase can be used in combination with a step induced thinning to form tunnel junctions for single electron transistor structures.
Morphological Evolution in Highly Strained InSb/InAs(001)
Authors: Seshadri Aruna , Millunchick J. Mirecki 
Published: April 2011

ABSTRACTWe investigated the morphological evolution of InSb grown on InAs (001) substrates (lattice mismatch = 6.9%) as a function of film thickness. Due to the very large lattice mismatch, growth proceeded via the Volmer-Weber mode. The morphological evolution of highly strained InSb films proceeds through several regimes as a function of thickness. The films initially nucleate isolated 3D islands even in the earliest stages of growth. The islands then coarsen and coalesce at slightly higher thicknesses, with some evidence of cooperative nucleation, or the sequential nucleation of islands and pits. Once the islands coalesce, the morphology evolves into long ridges aligned along the [110], however, those films are still discontinuous. At a thickness =100nm, the films finally become completely continuous and 2D growth proceeds via step flow of growth spirals present on the surface.
Cathodoluminescence Wavelength Imaging Study of Clustering in InAs/GaAs Self-Assembled Quantum Dots
Authors: Rich D. H. , Zhang C. , Mukhametzhanov I. , Madhukar A. 
Published: April 2011

ABSTRACTCathodoluminescence wavelength imaging (CLWI) of InAs/GaAs self-assembled quantum dots (SAQDs) was performed to study the spatial variation in the spectral lineshape of the broadened quantum dot (QD) ensemble. The lineshape was found to vary on a scale of ∼μm, revealing attendant variations in the size distribution of SAQD clusters on this spatial scale. Energy variations in clusters of SAQDs are found to exhibit a spatial correlation with the efficiency of luminescence and the activation energy for thermal re-emission of carriers. A reduction in the energy variation of the QD clusters occurs when the thickness of the spacer layers in vertically self-organized samples is reduced or the number of stacks is increased. SAQDs were also prepared by punctuated island growth (PIG), in which deposition of the total desired amount is broken into two or more stages each separated by time delays. CLWI reveals a reduced variation in the energy of the dominant CL emission on a ∼μm spatial scale, correlating with a narrower size distribution of larger QDs for PIG, as measured in atomic force microscopy.
Improved Carrier Transport in Intermixed GaAs/AlGaAs Laser Structure With Multi-Quantum Wells Cladding
Authors: Teng J. H. , Chua S. J. , Liu W. , Wang X. C. , Choi H. W. , Dong J. R. , Li G. , Braddoc D. 
Published: April 2011

ABSTRACTA GaAs/A1GaAs laser structure with multi-quantum-well cladding layer has been employed to investigate the group III interdiffusion. With this structure the photoluminescence (PL) signals from both the top C doped cladding layers and the laser active region quantum wells can be observed simultaneously. In contrast to the depth dependence of the group III vacancy enhanced interdiffusion, the quantum wells in the thick top cladding layer showed a uniform layer intermixing and the extent of intermixing was less than that observed in the quantum wells of the laser active region. The Al-Ga interdiffusion coefficient, DAl-Ga, of the cladding layer is about 4 times less than that of the active region. A more efficient carrier transport from the cladding layer to the active region in the intermixed sample was deduced from the temperature varied PL spectra. The built-in electric field is proposed to enhance the vacancy diffusion in the active region
Scanning Tunneling Spectroscopy Investigation of the Strained Si1−xGex-on-Si Band Offsets
Authors: Chen Xiangdong , Wang Xiang-Dong , Liu Kou-Chen , Kim Dong-Won , Banerjee Sanjay 
Published: April 2011

ABSTRACTThe band offsets and band gap are the most important parameters that determine the electrical and optical behavior of a heterojunction. In situscanning tunneling spectroscopy (STS) was employed to measure the valence band offset of strained Si1−xGex-on-Si (100) for the first time. The valence band offsets of strained Si0.77Ge0.23and Si0.59Ge0.41on Si(100) are found to be 0.21eV and 0.36eV, respectively. The results are in good agreement with theory and with results from other experimental methods. Due to band bending and surface states, it is difficult to determine the conduction band edge at the interface of Si1−xGex/Si exactly, but the conduction band offset is found to be much smaller than the valence band offset
Characterization of Morphology and Defects in Silicon-Germanium Virtual Substrates
Authors: Dilliway G.D.M. , Willoughby A.F.W. , Bonar J.M. 
Published: April 2011

ABSTRACTSilicon-germanium heterostructures incorporating virtual substrates are successfully used for both microelectronic and optoelectronic applications. However their use may be limited by the rough surface morphology and defect content, especially threading dislocations. High quality silicon-germanium heterostructures incorporating virtual substrates have been grown epitaxially using different techniques. Also various methods for improving the surface roughness and threading dislocation density have been reported. This study reports comparatively the effects of two different types of grading (linear and step wise) of the germanium concentration in the virtual substrate on the surface morphology and defect content of silicon-germanium heterostructures grown by Low Pressure Chemical Vapour Deposition (LPCVD) in the Southampton University Microelectronics Centre. Step-grading is demonstrated to produce superior virtual substrates
Uniformity Control of 3-Inch GaN/InGaN Layers Grown in Planetary Reactors®
Authors: Protzmann H. , Luenenbuerger M. , Bremser M. , Heuken M. , Juergensen H. 
Published: April 2011

ABSTRACTWe report on recent results obtained using an AIX 2400G3HT production type Planetary Reactor® in the 5×3 inch configuration for growth of typical group-III nitride layer structures consisting of GaN, InGaN and AlGaN. The optimum reactor geometry has been found by extensive modeling of the reactor design. Increased thermal management allows maximum reactor temperatures above 1400°C. As a consequence of extensive reactor modeling, the process transfer from 6×2 inch to 5×3 inch configuration was carried out by simple scaling of the corresponding process parameters of the 6×2 inch configuration. The scaling factor is calculated with respect to the changed reactor geometry. We used optical reflectrometry for in-situ growth control during this process development and could confirm the theoretical scaling requirements for obtaining identical growth conditions as compared to the 6×2 inch reactor configuration. This is verified by the generation of identical reflectance spectrum features. This important issue of in-situ control is discussed in detail. The TMGa efficiency could be kept at about 17%. Switching to the 8×3 inch configuration the efficiency increases up to about 27%, which is an improvement of 63% as compared to the 6×2 inch configuration
Growth of GaInNAs by Plasma Assisted Molecular Beam Epitaxy
Authors: Gotthold David W. , Govindaraju Sridhar , Holmes Archie L. , Streetman Ben G. 
Published: April 2011

ABSTRACTThe nitrogen containing alloy GaInNAs has attracted a great deal of interest recently for optoelectronic device applications at long wavelengths, especially 1.3µm, on GaAs substrates. What has been observed is that the material quality degrades rapidly with the addition of nitrogen. In this work we systematically explore the parameter space for the growth of GainNAs using plasma-assisted MBE and inert gas dilution. Inert gas dilution allows additional control of the production of active nitrogen; thus we can independently adjust RF power, gas flow rate, and nitrogen generation, which is used to study the effects of the plasma on the growth surface. In addition to examining the effects of plasma operating conditions, we will also explore the effects of other growth parameters (arsenic to nitrogen ratio and growth temperature) on the resultant structural and optical properties. These properties will be explored by photoluminescence, SIMS, and x-ray diffraction with the goal of understanding how nitrogen incorporation affects the resultant material properties. The resulting information is used to grow high quality layers for GaNAs avalanche photodiodes with a cut-off wavelength of 1.064µm
Atomic Force Microscopy Characterization of Interface Roughness of V-Shaped AlGaAs/GaAs Quantum Wire
Authors: Wang Xue-Lun , Voliotis Valia , Grousson Roger , Ogura Mutsuo 
Published: April 2011

ABSTRACTThe influence of surface roughness on the initial V-grooved substrate on the interface uniformity of V-shaped AIGaAs/GaAs quantum wires (QWRs) is investigated by direct atomic force microscopy observation of V-groove surface. We found that roughness on the initial V-grooved substrate induced during V-groove preparation processes can severely affect the interface uniformity of QWRs grown on it. We also found that roughness on the initial substrate can be greatly reduced by a simple etching treatment using a NH4OH:H2O2:H2O=1:3:50 solution, and this resulted in significant improvement of QWR interface quality.
Island Coalescence Induced Substructure Within GaP Epitaxial Layers Grown on (001), (111), (110) and (113) Si
Authors: Narayanan V. , Mahajan S. , Bachmann K. J. , Woods V. , Dietz N. 
Published: April 2011

ABSTRACTGaP islands grown on selected surfaces of Si and their coalescence behavior have been investigated by transmission electron microscopy. These layers were grown by chemical beam epitaxy. A number of significant observations emerge from this study. First, planar defect formation has been shown to be related to stacking errors on the smaller P-terminated {111} facets of GaP islands. Amongst the four orientations, (111) epilayers have a higher density of stacking faults and first order twins because of more P-terminated {111} facets per island. Second, multiple twinning on exposed {111} facets can produce tilt boundaries and irregular growths when islands coalesce. Third, inversion domain boundaries lying on {110} planes have been shown to form during GaP island coalescence across monatomic steps on (001) Si. Image simulations have been performed to show that these boundaries can be seen in high resolution lattice images and the observed contrast is attributed to the presence of wrong Ga-Ga and P-P bonds at the inversion boundary.
Oxidation Kinetics in SrTiO3 Homoepitaxy
Authors: Zhu X.D. , Si Weidong , Xi X.X. , Jiang Qidu 
Published: April 2011

ABSTRACTUsing an oblique-incidence optical reflectivity difference technique, we investigated kinetic processes in SrTiO3 homoepitaxy on SrTiO3(001) under pulsed laser deposition conditions. Depending upon growth temperature and oxygen ambient pressure, we found that the oxidation of an as-grown SrTiO3 monolayer may take a much longer time to complete than the recrystallization of the monolayer. The oxidation reaction was found to be characterized by an effective activation energy barrier of 1.35 eV and a large pre-exponential factor.
Optical Properties of Thin-Film SrTiO3 on Si Grown by MBE
Authors: Zollner Stefan , Demkov A.A. , Liu Ran , Curless J.A. , Yu Z. , Ramdani J. , Droopad R. 
Published: April 2011

ABSTRACTOxides with perovskite crystal structure such as SrTiO3 are important candidates for ultrathin gate oxides because of their large DC dielectric constant. When SrTiO3 is deposited directly on Si, an amorphous non-stoichiometric interfacial layer is usually formed during the later stages of growth, which reduces the specific capacitance and is therefore undesirable. We have performed deep-UV spectroscopic ellipsometry measurements from 0.7 to 6.6 eV of SrTiO3 films grown on Si by MBE. This technique is very well suited to determine the thickness of SrTiO3 films between 75 and 200 Å. For thinner films, refractive index and thickness cannot be determined independently. Ellipsometry measures the total thickness (SrTiO3 plus amorphous interfacial layer). There is no signature in the data that can be used to determine the SrTiO3 and interfacial layer thicknesses independently. We find that the effective refractive index (averaged over the crystalline SrTiO3 and the interfacial layer) decreases with decreasing thickness due to the increasing importance of the interfacial layer, but the overall critical-points due to interband transitions are not eliminated, therefore the electronic structure stays mostly intact.