bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Deformation and Reinforcement Particles on the Grain Growth Behavior of MoSi2
Authors: Basu Ajoy , Ghosh Amit 
Published: March 2011

AbstractThe grain growth behavior of polycrystalline MoSi2 and composites containing SiC particulates has been studied in the temperature range of 1200-1800°C during static annealing as well as under concurrent deformation conditions. Monolithic MoSi2, with ∼ 26 μm grain size appears to be extremely resistant to grain growth up to 1500°C. However, the grain growth rate above this temperature is quite rapid. When particulate reinforcements are used to reduce the grain size of MoSi2 to 4.4 μm, a stable microstructure is maintained up to 1500°C. Accelerated grain growth kinetics are observed at 1800°C under conditions of large plastic strain. This enhanced grain boundary mobility is associated with particle sweeping and particle agglomeration effects. At lower temperatures, where dislocation creep is the more dominant deformation mechanism these effects are absent. In the presence of a Si concentration gradient extremely high growth rates of columnar MoSi2 grains have been observed during reaction synthesis of MoSi2.
The Effects of in-Situ Processing Methods on the Microstructure and Fracture Toughness of V-V3Si Composites
Authors: Strum M. J. , Henshall G. A. , Bewlay B. P. , Sutliff J. A. , Jackson M. R. 
Published: March 2011

AbstractThe present paper describes ductile-phase toughening in V-V3Si in-situ composites that were produced by conventional arc melting (AM), cold-crucible induction melting (IM), and coldcrucible directional solidification (DS). Notched three-point bending tests were performed to determine the effects of synthesis method on the room temperature fracture toughness of eutectic compositions, which contain nearly equal volume fractions of V3Si and the V(Si) solid solution phase. Fracture toughness values ranged from 10 MPa√m for the AM eutectic to over 20 MPa√m for the IM and DS eutectic alloys. SEM fractography, fracture surface profiling, and chemical analyses were performed to correlate the toughness values with the microstructures and interstitial concentrations produced by the three synthesis methods.
Processing, Properties and Applications of High-Temperature Niobium Alloys
Authors: Wojcik C. Craig 
Published: March 2011

AbstractNiobium alloys are used in a variety of high-temperature applications ranging from light bulbs to rocket engines and nuclear reactors. The unique physical and chemical properties of these alloys have often dictated that only niobium alloys could fulfill certain application requirements. Compared to other refractory metals, niobium alloys have low density and are very ductile even at cryogenic temperatures. Most niobium alloys are also very resistant to corrosion by acids and liquid alkali metals; however, oxidation resistance at high temperatures is usually catastrophic unless protective coatings are used.An overview of the commercial high-temperature alloys is presented. Some of the unique properties of these alloys, which require unusual processing methods and equipment, are highlighted. Important physical properties of these alloys are discussed with reference to specific applications. The needs and design restraints of these applications provide valuable insights for those developing other high-temperature materials.
Creep Characteristics of Tungsten Wires
Authors: Wang Wego 
Published: March 2011

AbstractIn this study heavily-drawn tungsten wires were tested for creep at a constant load of 115 MPa in a 10-3 torr nitrogen atmosphere. These fine wires had an elongated rectangular grain morphology with small average grain sizes, 1.6 to 2.2 µm. The typical test sample wire was about 2.54 m long and 130 µm in diameter. The test wire was heated to the test temperature by self-resistance. The creep elongation was monitored by a transducer. Steady state creep rates were determined from the creep curves for four specimens that were tested at 1673, 1553, 1453, and 1273K, respectively. Diffusional creep is the predominant deformation mode. The experimental data were analyzed and compared with several creep theories: Ashby's combined, Coble's grain boundary and Nabarro's lattice diffusional creep models. The effects of recrystallization, grain aspect ratio, grain growth, impurity contents, nitrification and oxygen contamination on creep behavior are discussed in detail. However, their influences on creep kinetics are minimized in this study by carefully controlled experimental conditions. At a stress of 115 MPa, the grain boundary diffusional creep model successfully predicts the creep behavior at temperatures below 1453K. The instantaneous creep rate is inversely proportional to the cube of grain size at 1453K. The lattice diffusional creep model becomes predominant when the test temperature rises to 1553K. It is concluded that the creep behavior is controlled by grain boundary diffusion at a temperature below 1453K, and lattice diffusion above this temperature. Diffusion controlled creep and grain boundary sliding with diffusional accommodation are coupled in tungsten wires.
In-Situ Processing of Mosi2-Base Composites
Authors: Patibandla N. , Hillig W.B. , Ramakrishnan M.R. , Alman D.E. , Stoloff N.S. 
Published: March 2011

AbstractThree different methods of preparing Mosi2 and composites reinforced with ceramic fibers by reactive in-situ processing are described. Reactive powder sintering (co-synthesis) of elemental powders, chemical vapor infiltration/deposition and reactive vapor infiltration are examined. Monolithic Mosi2, SiC particle-reinforced Mosi2 or fibrous Mosi2 composites reinforced with Nicalon fiber were prepared. The advantages and disadvantages of these processes relative to more traditional processing techniques such as HIPing of prealloyed powders, mechanical alloying and a reported in-situ displacement reactions are discussed.
Fabrication and Testing of Plasma-Spray Formed MoSi2 and MoSi2 Composite Tubes
Authors: Castro R.G. , Hellmann J.R. , Segall A.E. , Shelleman D.L. 
Published: March 2011

AbstractPlasma-spray forming has been used to fabricate thick-wall tubes of Mosi2 and Mosi2 containing concentric layers of A12O3. This process is being investigated as a potential fabrication method for producing tubular components of Mosi2 and Mosi2 composites for use in high temperature fuel-burner applications. Results will be reported on the spray forming method used to produce tubes of various sizes. The room temperature strength of pure Mosi2 tubes in the as-deposited condition, and after heat-treating at 1500 °C for 2 hours in vacuum, will also be reported. The strength of plasma sprayed Mosi2 tubes were measured via diametral compression of 0-ring and C-ring sections in air at room temperature. Qualification of the strength distribution was based on Weibull statistical theory.
Plastic Behavior and Deformation Structure of Silicide Single Crystals with Transition Metals at High Temperatures
Authors: Umakoshi Y. , Nakashima T. , Nakano T. , Yanagisawa E. 
Published: March 2011

AbstractThe mechanical and plastic behaviors of refractory silicide single crystals with Cllb (MoSi2), C40 (CrSi2, TaSi2 and NbSi2), D88 (Ti5Si3) and Cl (CoSi2 and (Co0.9Ni0.1)Si2) structures were investigated. The C40–type silicides were deformed by (0001)<1120> slip. Their yield stress decreased sharply with increasing temperature but NbSi2 and TaSi2 which were deformable even at low temperatures, exhibited anomalous strengthening around 1350°C. Deformation of Ti5Si3 whose ductile-brittle transition occurred around 1300°C was controlled by twins and the brittle fracture occurred on the basal plane. In CoSi2 the {001}<100> slip was only activated at ambient temperatures but addition of Ni activated {110}<110> slip as secondary slip system and improved the ductility. The creep behavior of MoSi2 and CrSi2 single crystals were also investigated and was found to be controlled by the viscous and glide motion of dislocations.
Amorphous Phase Transformation During Rapid Thermal Annealing of Ion-Implanted Si
Authors: Kirillov D. , Powell R. A. , Hodul D. T. 
Published: March 2011

ABSTRACTVariations in the local order of the amorphous phase of Si produced by ion implantation and subjected to rapid thermal annealing were studied using the Raman scattering technique. It was found that the low order amorphous phase was formed independently of implantation ion species for low dose, low energy implantation at room temperature. For high energy, high dose implantation with heavy ions, the ion beam annealing effects were apparent and the higher order amorphous phase was formed. Rapid thermal annealing produced transformation from the low order phase to the high order amorphous phase. The continuous transformation was completed when the detectable crystalline phase regrowth started.
Structural Changes During Transient Post-Annealing of Preannealed and Arsenic Implanted Polycrystalline Silicon Films
Authors: Krause S. J. , Wilson S. R. , Gregory R. B. , Paulson W. M. , Leavitt J. A. , McIntyre L. C. , Seerveld J. L. , Stoss P. 
Published: March 2011

ABSTRACTPolycrystalline silicon films were transient preannealed, As implanted, and transient post-annealed at peak temperatures up to 1250°C for times up to 17.5 seconds. Structural changes occurring during post-annealing were examined by transmission electron microscopy. These results were correlated to Rutherford Backscattering and sheet resistance results. The grain size, which increased from 5–20 to 150–300 nm during preannealing, did not increase during post-annealing. During early stages of post-annealing, As diffused along grain boundaries and generated dislocation sources at grain boundary surfaces. Subsequently, as annealing progressed, a fine, As-rich cellular network structure propagated into the grains until the structure of an entire grain was transformed into a fine cellular network at the longest annealing times. Residual stresses in the film were relieved during formation of the network structure. The sheet resistance of preannealed samples, in comparison with non-preannealed samples with similar implantation and final transient anneals, was lower at shorter annealing times due to the larger grain size, which increased mobility, and the reduced grain boundary area, which trapped less As. It was also lower at longer annealing times due to the formation of the cellular network structure. In subsequent furnace stability tests for 30 minutes at 700–900°C, the sheet resistance increased less for preannealed than for non-preannealed samples.
DLTS Characterization of N-Type Silicon After Rapid Thermal Annealing of Boron Implantation
Authors: Ransom C. M. , Sedgwick T. O. , Cohen S. A. 
Published: March 2011

ABSTRACTDLTS measurements show that majority-carrier traps exist after quartz-lamp, rapid-thermal annealing (RTA) activation of B+ and BF2+ ion implants in n-type silicon. Levels at Ec-0.17, 0.27, 0.44 and 0.57 eV annealed out with an additional 20 minute isochronal anneal at 550°C in argon. A stable defect at 0.37 eV existed at temperatures above 750°C. DLTS measurements of a Schottky diode on n-type silicon after only RTA indicated that electron traps could be introduced into n-type silicon by the RTA alone.
An Overview and Comparison of Rapid Thermal Processing Equipment: a Users Viewpoint
Authors: Wilson S. R. , Gregory R. B. , Paulson W. M. 
Published: March 2011

ABSTRACTFive different RTP units have been examined. These are the Varian RTP-800, the Eaton ROA-400, the A.G. Associates 2101/2106, the Tamarack 180A-C and the Varian IA-200. Each system is a cassette-to-cassette serial processor designed for use in a high volume semiconductor fabrication line. These units will heat a wafer from room temperature to 400–1400C in times on the order of a few seconds. Each unit uses radiation to heat and cool the wafer. The different radiation sources, wafer handling systems, temperature measurements and control computers are discussed. The control of slip and nonuniform temperatures is presented as well as information regarding the types of ambients that can be used in each system.
Process Control for a Rapid Optical Annealing System
Authors: Gelpey Jeffrey C. , Stump Paul O. , Smith John W. 
Published: March 2011

ABSTRACTWhen high temperature processes are being carried out in a diffusion furnace, temperature control is accomplished in a straight forward manner. By using thermocouples and a proportional controller, sufficient accuracy and control are available to the process engineer.But with the current shift toward the more rapid annealing schemes, better control is a necessity. In order to achieve this accuracy, especially when the heat source is a 100 kilowatt arc lamp, more sophisticated control methods must be employed. By using an optical pyrometer tuned to operate at a wavelength where external interferences are minimized, wafer temperature may be monitored to a high degree of accuracy and with the fast response times needed.Coupling the output of the pyrometer to a microprocessor based controller allows the engineer to create and use multi stepped time/temperature profiles which are highly repeatable.This paper will describe such a system and how it is used in a production oriented rapid optical annealing system.
The Effect of Thin Dielectric Films on the Accuracy of Pyrometric Temperature Measurement
Authors: Pettibone D. W. , Suarez J. R. , Gat A. 
Published: March 2011

ABSTRACTPyrometers are used to measure wafer temperature in rapid thermal processors. This paper focuses on the effect of thin dielectric films on the accuracy of pyrometric temperature measurement. The thin films affect the emissivity of the wafer, which in turn affects the radiation emitted by the wafer. Wafers with different oxide thicknesses were monitored by both pyrometer and thermocouple. Temperature errors of the order of 10°C to 50°C were found for wafers of differing oxide thicknesses. The chamber reflectivity was found to be an important factor in determining the ‘effective’ emissivity of the wafer. Pyrometer recalibration is necessary to accurately measure wafer temperature.
Characterization of PSG Films Reflowed in Steam Using Rapid Thermal Processing
Authors: Shah N. , Vittie J. M. C. , Sharif N. , Nulman J. , Gat A. 
Published: March 2011

ABSTRACTThis study describes the use of a steam environment to reflow phosphosilicate glass (PSG) samples using a HEATPULSE® rapid thermal annealer. The samples comprised PSG over poly steps and of open contacts in PSG. It was observed that reflow occurs 50°C lower in steam than in dry O2. An acceptable flow cycle for 8 w/o P in PSG glass is 1050°C for 10 seconds in steam, while for 6 w/o P PSG it is 1100°C for 10 seconds. Steam is found to be an effective amibient for densification of the PSG film. The thermal oxide grown in the contact during opening reflow was determined to be near 140 A. The operating regime for a junction depth <0.4 um and a reflow angle < 75° is presented for 8 w/o P.
Rapid Isothermal Fusion of BPSG Films
Authors: Mercier J. S. , Madsen L. D. , Calder I. O. 
Published: March 2011

ABSTRACTA study on the rapid isothermal fusion (RIF) properties of borophosphosilicate glass (BPSG) films is presented. Conventional furnace fusion (FF) results are also reported for comparison purposes. The effects of varyinq the temperature (950°-1150°C for RIF, and 800°-1000°C for FF) and the cycle duration (5–60 s for RIF, and 7–60 min for FF) were investigated in a N2 ambient. Two deposition methods were used for the BPSG films, namely atmos- Dheric pressure CVD (APCVD) and low pressure CVD (LPCVD), both with the low temperature oxidation of SiH4, PH3 and B2H6 as a deposition reaction mechanism. The boron and phosphorus concentrations were maintained at 4 w/o for both species. Step coveraae fusion test structures were used to characterize the qlass flow. It was found that for both RIF and FF techniques, a considerable amount of fusion resulted from heating cycles which are compatible with the shallow Junctions required for VLSIC's. With BPSG, the choice between RIF and FF can thus be based on criteria other than olass fusion, such as shallow junction annealing. Also, more fusion was obtained for LPCVD films than for APCVD films.
Characterization of Tungsten Silicides Formed by Rapid Thermal Annealing.
Authors: Siegal M. , Santiago J. J. , Van der Spiegel J. 
Published: March 2011

ABSTRACTTungsten silicide samples were formed by sputter depositing 80 nm W metal onto (100) oriented, 5 ohm-cm Si wafers. After deposition, the samples were fast radiatively processed in an RTA system using quartz-halogen tungsten lamps as radiation sources for time intervals ranging from 20 to 60s under high vacuum. Films processed at 22–25 W/cm2 radiation with the film side of the samples oriented away from the lamps result in films which are metallic or cloudy in color, and have mixed composition as evidenced by x-ray diffraction (W, W5 Si3 and WSi2). Films processed with the film side oriented toward the lamps show the occurrence of a phase transforF.ation clearly nucleated at the film edge. The new phase is grey and mostly composed of WSi2, with film resistivities 55–60 μΩ-cm. AES measurements show a uniformly distributed Si diffusion profile into the metal film, while SEM indicates a nucleation and growth of the phase once diffusion occurs.
Diffusion Modeling of the Redistribution of Ion Implanted Impurities
Authors: Michel Alwin E. 
Published: March 2011

ABSTRACTTransient enhanced diffusion during rapid thermal processing has been reported for most of the common dopants employed for silicon device fabrication. For arsenic a large amount of the available data is fit by a computational model based on accepted diffusion mechanisms. Ion implanted boron on the other hand exhibits anomalous tails and transient motiou. A time dependence of this displacement is demonstrated at lower temperatures. High temperature rapid anneals are shown to reduce some of the anomalous motion observed for low temperature furnace anneals. A model is described that links the electrical activation with the diffusion and describes both the transient diffusion of rapid thermal processing and the large anomalous diffusion reported many years ago for furnace anneals.
Silicon Oxidation by Rapid Thermal Processing (RTP)
Authors: Hodge A. M. , Pickering C. , Pidduck A. J. , Hardeman R. W. 
Published: March 2011

ABSTRACTSingle crystal silicon wafers have been oxidised by exposure to an oxygen ambient at atmospheric pressure during RTP using an A G Associates Heatpulse 2101 Rapid Thermal Annealer. Wafers of the standard orientations used in silicon device processing <100>, <111> and <110> were studied. Oxidation was carried out in the temperature range 900 to 1250°C for times of RTP from 4 to 25U seconds producing oxides up to 60nm in thickness. Oxidation rates and their orientation and temperature dependence were derived from ellipsometric measurements of oxide thickness. X-ray photoelectron spectroscopy (XPS) and infra-red absorption spectrophotometry were also employed in the oxide characterisation. Preliminary electrical characterisation of the oxides, investigated using MOS C-V analyses, showed that the interface state densities were comparable to those in conventional furnace grown oxides.
Oxide Growth Using the Water-Wall Arc Lamp
Authors: Gelpey Jeffrey C. , Stump Paul O. , Capodilupo Ronald A. 
Published: March 2011

ABSTRACTThe uses of Rapid Thermal Annealing or Rapid Thermal Processing (RTP) have been expanding beyond the original post implant annealing. RTP has been used to reflow low temperature oxides (PSG or BPSG), anneal silicides and to sinter contacts. One application of RTP which is beginning to receive attention is the growth of oxides or nitrides of silicon.This paper will examine the use of a commercial rapid thermal processing system based on a very high power water-wall DC arc lamp to grow oxides on silicon wafers. The work includes a study of the growth rates of oxides at different temperatures. Direct feedback control of wafer temperature and high ramp-up and cool-down rates are used to minimize the effects of temperature errors or “tails” in the temperature/time profiles. Ellipsometry is used as the primary measurement tool to characterize the oxide films.In addition to using a pure, dry oxygen atmosphere, several oxygen-argon mixtures are used. The effects of atmosphere on the growth rate of the oxide film are reported.In order to become a practical application of RTP, oxide growth must be accomplished uniformly and reproducibly. These characteristics are machine-dependent. The uniformity of films grown in this system are discussed. The growth of oxide films and the uniformity measurements are used as an indirect technique to characterize the uniformity of the system. The reproducibility of film thickness is also examined.
Kinetic Studies of Silicon - Silicon Dioxide Interface Trap Annealing Using Rapid Thermal Processing
Authors: Reed Michael L. , Plummer James D. 
Published: March 2011

ABSTRACTRapid thermal processing is a promising tool for studying the kinetics of interface state annealing and other process phenomena on short time scales. We have studied the decay of interface states with a variety of ambients, temperatures, and oxide thicknesses. Annealing kinetics appear to be controlled by a surface reaction process, and not hydrogen diffusion through the oxide. The annealing behavior depends strongly on temperature but less so on other process parameters. Our experimental methodology for temporal process modeling is discussed.
Damage Removal Processes in Ion Implanted, Rapidly Annealed GaAs
Authors: Jacobson D. C. , Pearton S. J. , Hull R. , Poate J. M. , Williams J. S. 
Published: March 2011

ABSTRACTThe removal of lattice damage and consequent activation by rapid thermal annealing of implanted Si, Se, Zn and Be in GaAs was investigated by capacitance-voltage profiling, Hall measurements, transmission electron microscopy (TEM), secondary ion mass spectrometry and Rutherford backscattering. The lighter species show optimum electrical characteristics at lower annealing temperatures (˜850°C for Be, ˜950°C for Si) than the heavier species (˜900°C for Zn, ˜1000°C for Se), consistent with the amount of lattice damage remaining after annealing. TEM reveals the formation of high densities (107 cm−2) of dislocation loops after 800°C, 3s anneals of high dose (1×1015 cm−2) implanted GaAs, which are gradually reduced in density after higher temperatures anneals (˜1000°C). The remaining loops do not appear to effect the electrical activation or carrier mobility in the implanted layer, the latter being comparable to bulk values.
The Effect of Impurities in the SPE Kinetics in GaAs
Authors: Licoppe C. , Nissim Y. I. , Meriadec C. 
Published: March 2011

ABSTRACTSolid phase epitaxial (SPE) growth of ion implanted GaAs layers has been studied using the time resolved reflectivity technique. A series of implanted impurities have been selected to study the dependance of the nature of the impurity on the growth kinetics. It has been found that the activation energy and the kinetics of growth were independant on the choice of implanted substitutional impurity. Only impurities such as Argon were responsible of a large decrease in the regrowth rate. The same technique is shown to bring informations on the amorphous-crystal interface structure during growth. From these informations it has been possible to show that interface roughening occured during SPE in (100) GaAs. This interface evolution is an intrinsic property of the implanted GaAs material.