bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Selective Etching of SiO2/Si by ArF Excimer Laser
Authors: Kitamura K. , Murahara M. 
Published: March 2011

AbstractDry etching of SiO2 insulation layer has been required in the Si semiconductor manufacturing process. The etching of SiO2/Si is chemically carried out by using HF solution. We successfully demonstrated a new method for exclusive etching of SiO2 using the nitrosyle fluoride (NFO) gas which was produced from the mixed gas of NF3 and O2 with an ArF excimer laser irradiation.SiO2 and Si substrates were placed side by side in a reaction cell which was filled with 3% O2 gas in NF3 at the gas pressure of 380 Torr. ArF excimer laser beam was irradiated parallel to the substrates. The laser fluence was kept at lOOmJ/cm2. As soon as the mixed gas of NF3 and O2 was irradiated with the ArF laser beam, an intermediate product of NFO was produced. The chemical behavior of NFO was confirmed from the UV absorption spectrum with absorption in the 310 to 330nm wavelength region. In the presence of SiO2, the absorption of NFO diminished. The absorption of NO2, instead of NFO, appeared at 350nm. This indicates that the oxygen atoms of SiO2 were pulled out by NFO.The etching reactions continued for 3 minutes after irradiation when the SiO2 and Si substrates were kept in an atmosphere of the reactant gases. As a result, not the Si but SiO2 substrate was etched with the depth of 2000Å.
Plasma Etching and Surface Analysis of a-SiC:H Films Deposited by Low Temperature Plasma Enhanced Chemical Vapor Deposition
Authors: Thomas J. H. , Loboda M. J. , Seifferly J. A. 
Published: March 2011

AbstractOrganosilicon precursors were used to deposit thin films of highly stable amorphous hydrogenated silicon carbide at low temperatures by plasma enhanced chemical vapor deposition. X-ray photoemission and Auger electron spectroscopy were employed to characterize the surface chemistry of air exposed and plasma etched films. Auger analysis of the as-deposited material shows its composition to be constant throughout its depth. RF plasma etching was performed in CF4/O2 and SF6/O2 gas mixtures. Etch rates in these atmospheres are similar to those reported in the literature. After plasma etching, the surface was converted to a highly fluorinated state. In addition to the expected SiC bond, Si-OF bonds were found after plasma etching. Fluorocarbon residue was not produced in this process. Chlorine etching of this low temperature PECVD film is described and is shown to be compatible with standard integrated circuit manufacture processing as an hermetic-like sealant.
Surface Perturbation by Energetic Particle Beams
Authors: Chang Che-Chen , Yang Jung-Yen , Shieh Jaw-Chang 
Published: March 2011

AbstractThe state of the surface after energetic keV particle bombardment is investigated using molecular dynamics. The model utilizes a Ag{110} microcrystallite which is statically bombarded by Ar particles at normal incidence. After being bombarded at incident energy of 1 keV, the relocation probability is <0.3 for all the surface atoms initially residing within four lattice spacings from the target. The probability decreases exponentially as the initial distance of the substrate atom from the target is increased. The most probable distances of displacement from the lattice site also vary with the initial atomic distance from the target atom. The probable displacement of the surface atom, except the target atom, is less than one twentieth of the surface lattice spacing. An analytical formulae for the initial-distance dependence of the relocation probability is also proposed. The formula has three adjustable parameters which are determined by the least-squares method.
Cleaning during Initial Stages of Epitaxial Growth in an Ultrahigh Vacuum Rapid Thermal Chemical Vapor Deposition Reactor
Authors: Sanganeria Mahesh K. , Violette Katherine E. , ÖZtÜRk Mehmet C. , Harris Gari , Lee C. Archie , Maher Dennis. M. 
Published: March 2011

AbstractIn this paper, we report our results on surface preparation for the growth of epitaxial Si films. Hydrogen passivated surfaces are currently being investigated for application in Si epitaxy to eliminate the high temperature in-situ bake necessary to remove the native oxide. Hydrogen passivation is obtained by a dilute HF dip before the substrate is loaded in the process chamber. However the passivation is partially lost when the HF dip is followed by a water rinse which results in oxygen absorption on the substrate. It was found that the peak oxygen concentration at the epitaxy substrate interface increase by an order of magnitude due to a five minute water rinse. We report here that oxygen and carbon at the epitaxy substrate interface can be desorbed during initial stage of epitaxial growth by reducing epitaxial growth rate. In this work, epitaxial Si films were deposited over a wide range of growth rates obtained by varying Si2H6 flow rates. The peak oxygen concentration decreases by an order of magnitude by changing the growth rate from 3000 to 700Å/kminute for a deposition temperature of 800°C. We believe that at higher growth rates Si overgrows on absorbed oxygen maintaining epitaxial alignment reflected in the good electrical quality of the epitaxial films. However, at low growth rates oxygen has sufficient time to desorb before overgrowth can take place, improving the epitaxy substrate interface quality.
Growth and Characterization of Si-GaP and Si-GaP-Si Heterostructures
Authors: Dietz N. , Habermehl S. , Kelliher J. T. , Lucovsky G. , Bachmann K. J. 
Published: March 2011

AbstractThe low temperature epitaxial growth of Si / GaP / Si heterostructures is investigated with the aim using GaP as a dielectric isolation layer for Si circuits. GaP layers have been deposited on Si(100) surfaces by chemical beam epitaxy (CBE) using tertiarybutyl phosphine (TBP) and triethylgallium (TEG) as source materials. The influence of the cleaning and passivation of the GaP surface has been studied in-situ by AES and LEED, with high quality epitaxial growth proceeding on vicinal GaP(100) substrates. Si / GaP / Si heterostructures have been investigated by cross sectional high resolution transmission electron microscope (HRTEM) and secondary ion mass spectroscope (SIMS). These methods reveal the formation of an amorphous SiC interlayer between the Si substrate and GaP film due to diffusion of carbon generated in the decomposition of the metalorganic precursors at the surface to the GaP/Si interface upon prolonged growth (layer thickness > 300Å). The formation of twins parallel to {111} variants in the GaP epilayer are extended into the subsequently grown Si film with minor generation of new twins.
Growth Kinetics and Corresponding Luminescence Characteristics of Amorphous C:H Deposited from Ch4 by Dc Saddle-Field Plasma-Assisted Cvd
Authors: Kruzelecky Roman V. , Wang Chun , Zukotynski Stefan 
Published: March 2011

AbstractHydrogenated amorphous carbon (a-C:H) thin films were deposited onto various substrates at 200 °C by DC saddle-field glow-discharge dissociation of CH4. In situ plasma probe mass and energy spectroscopy was employed to systematically study the effects of the discharge parameters on the formation of reactive precursors. The ion current at the substrate holder consists mainly of CH3+ for pressures < 75 mTorr; higher pressures and lower discharge currents encourage the formation of C2Hn+ and C3Hn+ radicals in the discharge. The growth rate was largely independent of the total pressure, increasing approximately linearly with the discharge current. Under 476 nm photo-excitation, the a-C:H films exhibited room-temperature photoluminescence in the visible, near 1.9 eV, with an intensity that was strongly dependant on the discharge parameters.
Molecular Dynamics Simulation of Large Cluster Growth
Authors: Zachariah Michael R. , Carrier Michael J. , Blaisten-Barojas Estela 
Published: March 2011

AbstractClassical Molecular dynamics simulation of silicon cluster growth (up to 1000 atoms) have been conducted using the Stillinger-Weber 3-body interaction potential. The cluster binding energy has been fit to an expression that separates the surface and bulk contribution to the energy over a wide temperature and size range. Cluster growth simulations show that large heat release results from new bond formation at gas kinetic rates (i.e. sticking coefficient = unity). Temperature was found to be the primary controlling process parameter in the evolution of cluster morphology from an aggregate to a coalesced cluster below 1000 K, with the impact parameter playing a secondary role.
Thermochemical Data for CVD Modeling from Ab initio Calculations
Authors: Ho Pauline , Melius Carl F. 
Published: March 2011

AbstractAb initio electronic-structure calculations are combined with empirical bond-additivity corrections to yield thermochemical properties of gas-phase molecules. A self-consistent set of heats of formation for molecules in the Si-H, Si-H-Cl, Si-H-F, Si-N-H and Si-NH- F systems is presented, along with preliminary values for some Si-O-C-H species.
Growth of Epitaxial β-SiC Films on Porous Si(100) Substrates from MTS in a Hot Wall LPCVD Reactor
Authors: Chiu Chien C. , Desu Seshu B. , Chen Gang 
Published: March 2011

Abstractβ–SiC thin films were epitaxially grown on porous Si(100) substrates at 1150° C from methyltrichlorosilane (CH3SiCl3 or MTS) in a hot wall reactor by Vsing low pressure chemical vapor deposition (LPCVD). The growth rate was 120 Å/min. Epitaxial β–SiC(100) thin films were obtained after a deposition time of 12.5 min. The crystallinity of the β–SiC films was affected by the deposition time. For instance, rotational β–SiC(100) crystals and polycrystalline β–SiC with a highly preferred orientation of (100) planes were observed for a deposition time of 50 min. The results from XRD and TEM indicated that polycrystalline β–SiC films with a preferred orientation of β–SiC(111) appeared after further increasing the deposition times (time ≥ 75 min). The change in crystallinity is attributed to increasing roughness with increasing deposition time.
Precursor Delivery for the Deposition of Superconducting Oxides: a Comparison Between Solid Sources and Aerosol
Authors: Thomas O. , Weiss F. , Hudner J. , Haase R. , Dubourdieu C. , Mossang E. , Didier N. , Senateur J.P. 
Published: March 2011

AbstractEpitaxial thin layers of YBa 2Cu 3O7−x (Tc=90 K, Jc (OT, 77 K) = 2 106 A cm-2) were synthesised by thermal decomposition (750 − 830 °C) of tetramethylheptanedionates of yttrium, barium and copper in the presence of oxygen. Three different precursor delivery systems have been used: In the first, the precursor's surface is flushed with the carrier gas (Ar), in the second, argon is directly injected through the powder leading to a much higher transport rate, and in the third, a liquid (diketonates in a solvent) is nebulized via a piezoelectric transducer. The transport and deposition rates obtained in these three different reactors will be compared.
LPCVD of InN on GaAs(110) Using HN3 and TMIn: Comparison with Si(100) Results
Authors: Bu Y. , Lin M.C. 
Published: March 2011

AbstractLow-pressure chemical vapor deposition (LPCVD) of InN and laser-assisted LPCVD on GaAs(110) and Si(100) using HN3 and trimethyl indium (TMIn) has been studied with XPS, UPS and SEM. Without 308-nm excimer laser irradiation, InN film was built on the GaAs but not on Si surface under the present low-pressure conditions. When the photon beam was introduced, InN films with In:N atomic ratio of 1.0±0.1 and a thickness of more than 20 Å (the limit of the electron escaping depth for the In3d X-ray photoelectrons) were formed on Si(100) surface. In both cases, the formation of surface nitrides at the initial film growth processes was clearly indicated in the XPS spectra. The He(II) UP spectra taken from InN films on GaAs and Si are nearly identical and agree well with the result of a pseudo-potential calculation for the InN valence band. The corresponding SEM pictures showed smooth InN films on GaAs(110), while grains with diameter of ∼100 nm were observed for InN on Si(100).
Synthesis and Decomposition of a Novel Carboxylate Precursor to Indium Oxide
Authors: Hepp Aloysius F. , Andras Maria T. , Duraj Stan A. , Clark Eric B. , Hehemann David G. , Scheiman Daniel A. , Fanwick Phillip E. 
Published: March 2011

AbstractReaction of metallic indium with benzoyl peroxide in 4-methylpyridine (4-Mepy) at 25 °C produces an eight-coordinate mononuclear indium(III) benzoate, In(η2-O2CC6H5)3(4- Mepy)2 4H2O (I), in yields of up to 60%. The indium(III) benzoate was fully characterized by elemental analysis, spectroscopy, and X-ray crystallography; (I) exists in the crystalline state as discrete eight-coordinate molecules; the coordination sphere around the central indium atom is best described as pseudo-square pyramidal. Thermogravimetric analysis of (I) and X-ray diffraction powder studies on the resulting pyrolysate demonstrate that this new benzoate is an inorganic precursor to indium oxide. Decomposition of (I) occurs first by loss of 4-methylpyridine ligands (100°-200°C), then loss of benzoates with formation of In2O3 at 450°C. We discuss both use of carboxylates as precursors and our approach to their preparation.
Optimization of Jc for Photo-Assisted MOCVD Prepared YBCO Thin Films by Robust Design
Authors: Chou P. C. , Zhong Q. , Li Q. L. , Ignatiev A. , Wang C. Y. , Deal E. E. , Chen J. G. 
Published: March 2011

AbstractMetalorganic chemical vapor deposition (MOCVD) is emerging as a practical high Tc superconducting thin film preparation technique for industrial application. Intrinsically this technique involves a large number of variable parameters. This is especially critical for the quarternary or higher high Tc materials. Thus, effective methods are required to optimize the parameters for the preparation of high Tc films. A matrix experimental design named Robust Design has been employed for this purpose. The first-phase design was based on a starting knowledge of growth temperature and pressure, and annealing temperature for MOCVD preparation of YBCO thin films. A minimum lab effort of only nine deposition experiments was then used to optimize the process control parameters of precursor oven temperature, carrier gas (Ar) flow rate, O2 flow rate and N2O flow rate. The results were then followed by three confirmation depositions. The Robust Design resulted in the growth of YBCO film with Tc consistently in the range of 87.0 K to 90.2 K and Jc improved from about 1.0 × 106 A/cm2 to 3–5 × 106 A/cm2.
Epitaxial Growth of Ba1−xSrxTiO3 Thin Films on YBa2Cu3O7−x Electrode by PE-MOCVD
Authors: Chern C.S. , Liang S. , Shi Z.Q. , Yoon S. , Safari A. , Lu P. , Kear B.H. 
Published: March 2011

AbstractPlasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD) has been successfully employed for the deposition of (100) oriented barium strontium titanate (BST) thin films on a variety of substrate and electrode materials. The incorporation of O2 plasma, which was used as oxidation reactant, has helped to reduce the required temperature for deposition of high-quality STO and BST thin films. This low temperature processing may make it possible to integrate BST on Si and GaAs. BST films with low leakage current densities of about 10−7 A/cm2 at 2-volt (about 105 V/cm) operation were obtained from PE-MOCVD processing. Moreover, the BST results of capacitance-temperature (C-T) measurements show that most of the PE-MOCVD BST films have Curie temperatures of about 30–35°C and a peak dielectric constant of 600–800 at zero bias voltage, The sharp transition in the C-T data indicates that the BST films may have a high induced pyroelectric coefficient at room temperature, which is highly desirable for uncooled IR imaging arrays. The x-ray diffraction and Rutherford backscattering spectrometry results show that the BST film composition reproducibility was well controlled at around Ba0.75Sr0.25TiO3 with a 4% variation. Device quality BST thin films with the thickness of 1000–2000 Å were produced. These results indicate that PE-MOCVD has high potential to be further developed and promoted as a production deposition technique providing high permittivity dielectric thin films for microelectronics and IR sensor industries.
Raman Spectra of MOCVD-Grown Ferroelectric PbTiO3 Thin Films
Authors: Feng Z. C. , Kwak B. S. , Erbil A. , Boatner L. A. 
Published: March 2011

AbstractLead titanate (PbTiO3) has been grown on a variety of substrates by using the metalorganic chemical vapor deposition (MOCVD) technique. The substrates employed included Si, GaAs, MgO, fused-quartz, sapphire, and KTaO3. Raman spectra from these heterostructures are presented. All of the films exhibited the strong, narrow spectral features characteristic of PbTiO3 perovskite-oxide crystals and indicative of high crystalline quality. Temperature behaviors of the Raman modes, including the socalled “soft-mode”, were studied. A “difference-Raman” technique was used to distinguish the contributions of the PbTiO3 film and the KTaO3 single-crystal substrate.
Recent Advances in the CVD of Metal Nitrides and Oxides
Authors: Gordon Roy G. 
Published: March 2011

AbstractUse of metal-organic precursor materials has permitted thermal CVD of many metal nitrides at remarkably low temperatures and without corrosive by-products. Metallic TiN, VN, Nb3N4 and Mo2N3; semiconducting GaN and Sn3N4; and insulating AIN, Zr3N4, Hf3N4 and Ta3N5 can be deposited at temperatures typically in the range 100 to 400 C. Deposits free of carbon are obtained by transamination reactions of metal dialkylamido precursors with a sufficiently large excess of ammonia. The resulting TiN films are good diffusion barriers, and provide low contact resistance between metals and silicon.Transparent semiconducting oxide films, such as SnO2, ZnO and TiO2, are often made by MOCVD for use in solar cells, energy-efficient window coatings and electro-optical displays. These wide band-gap semiconductors can be doped to n-type conductivity by a variety of dopant elements. Fluorine is the dopant which produces materials with the highest electron mobility, conductivity and transparency, by substituting for oxygen. Certain organic fluorine compounds have been found to be very effective fluorine dopants for these CVD reactions, yielding films with very shallow donors having nearly 100 % electrical activity.Precursors for the CVD of alkaline earth metal oxides, particularly barium, lack the volatility and stability needed for reproducible deposition of superconducting, ferroelectric or magnetic oxides. Use of ammonia or volatile amines as carrier gases greatly enhances the volatility and stability of betadiketonates of barium, strontium and calcium, providing high and stable transport rates for source temperatures below 100 C, even for non-fluorinated ligands.
Electron Microscopical Observations of Graphite in Cast Irons
Authors: Purdy Gary R. , Audier Marc 
Published: March 2011

ABSTRACTGraphite flakes and spheroids, extracted from rare-earth treated cast irons, have been examined using electron microscopy. Transmission microscopy has been used to investigate the defect structure of flakes and to demonstrate the concentric aromatic shell structure of spheroids. Each spheroid is shown to possess a rare-earth containing core or nucleus.High resolution lattice images are presented as evidence for the presence of amorphous regions within flake graphite crystals. For spheroidal graphite, the lattice images indicate a greater degree of crystalline perfection. In addition, they suggest:1) The presence of intercalation structures2) The presence of an amorphous phase, on the graphite-iron interface, from which crystalline graphite forms at growth sites.The implications for possible mechanisms of graphite crystallization are discussed.
Contributions to the Study of the Solidification Mechanism and of the Influence of Structure on the Properties of Compacted/Vermicular Graphite Cast Iron
Authors: Riposan I. , Chisamera M. , Sofroni L. , Brabie V. 
Published: March 2011

ABSTRACTIn the paper we have analysed some aspects of the structural,mechanical, technological and casting properties of compacted/vermicular graphite(C/VG)cast iron,with reference to our works published in the past 10 years.As regards the primary structure(eutectic solidification)we were interested in the composition and growth conditions of eutectic cells, of C/VG formation,on the basis of Mg and Si distribution,of intergranular phases,in different cooling conditions.We have also analysed the carbide formation and the inverse chill tendency. C/VG is characterised by form factors(compactness)on whose basis we propose some new typical graphite forms. The tendency to ferritic shells formation in the case of C/VG is compared with that recorded for NG,coral graphite,and FG type A,B,D. We note the possibility of favouring pearlite Dy thermal treatment,alloying and the use of a treatment-alloy with Al,Ti and other elements with a pearlitic action.We have also analysed the influence of wall thickness,cross-section geometry,holding time,anti- spheroidizing elements,nature of casting mould upon structure.Finally,we present a synthesis of the applicational properties,based on our data.
A Study of the Shrinkage and Dilatation during Solidification of Nodular Cast Iron - its Relation to the Morphology of Crystallisation
Authors: Hummer R. 
Published: March 2011

ABSTRACTThis study deals with the solidification behaviour of cast iron with nodular graphite. By measurement of the “apparent shrinkage” the real feeding requirement can be determined under operating conditions. By means of cooling curves and measurements of dilatation the mode of solidification is established. The results are in accordance with today's knowledge of the morphology of crystallisation and offer an operating hypothesis for feeding technique in practice.
Formation of Internal Defects in S.G. Cast Irons in Relation to the Solidification Process
Authors: Lesoult G. , Dietrich P. , Arnould F. , Theret J. M. 
Published: March 2011

ABSTRACTIt is well known that ductile iron is more prone to the formation of internal defects and to the swelling-out of the mold than grey iron. This is likely related to differences in the way the volume changes due to solidification and graphitization occur for these two cast irons. Direct study of these phenomena is difficult because interdendritic feeding and graphite expansion are intimately related.A simple physical model is proposed to simulate the effects of a few variables on the tendency for a S.G. cast iron to lead to a casting with internal defects: its chemical composition, inoculation and the rate of heat extraction.The aim of the model is to calculate the pressure of the residual liquid at any point of the casting during its solidification. A special attention is payed to the pressure drop due to the movement of the residual liquid in the mushy zone. Therefore the evolution of the fractions of liquid, austenite and graphite are taken into account for calculating the local volume changes which are assumed to be the main driving forces for the liquid flow. In the same time, the evolution of the permeability of the mushy zone is estimated for calculating the liquid flow pattern and the pressure drop pattern.The numerical values for the quantities which describe the solidification of the cast iron are issued from quantitative image analysis of samples quenched during directional solidification (Q.D.S.).
Solidification Behavior of Technical Metastable Near-Eutectic Iron-Carbon Alloys (Experimental and Numerical Simulation)
Authors: Wolf G. , Flender E. , Sahm P. R. 
Published: March 2011

ABSTRACTBy way of unidirectional solidification, the critical parameters of the transition from a metastable to a stable eutectic in technical cast-iron alloys were investigated. A critical growth rate which was determined for near-eutectic alloys can be attributed to the stable-to-metastable transition. The structural parameters for the metastable eutectic were defined as a function of the growth rates.