bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fracture Toughness of Diamond Measured by Vickers Indenter Reloading Technique
Authors: Dub Sergey N. 
Published: April 2011

ABSTRACTThe crack initiation sequence during Vickers indenter penetration into the (100) plane of diamond was observed. It was revealed that for <110> orientation, two median cracks are initiated during the loading half of the cycle. In unloading, the median cracks grow toward the surface and turn into half-penny cracks. It was proposed to use half-penny cracks as initials and evaluate fracture toughness in second loading from a crack-starting load for these cracks. The length of initial half-penny cracks was measured after first loading cycle from opposite side of the sample. Test results obtained by the reloading technique agree well with the data on conventional fracture toughness determination by indentation from the length of cracks after unloading.
The Unique Strength of Diamond
Authors: Gilman John J. 
Published: April 2011

ABSTRACTThe features of diamond that make it unique are: 1] its efficient tetrahedral structure which is stabilized by resonance of the bonding electrons among adjacent bonds; 2] the exceptionallly high ratios of its shear moduli to its bulk modulus; 3] the large gap between the top of its valence band and the bottom of its conduction band which makes dislocation mobility very low in it; 4] its high surface energy. Although diamond is nearly elastically Isotropic, the ratio of its C44 shear constant to its bulk modulus is 1.3 which is the highest measured value for this ratio. It is quite unusual for it to be greater than unity. This high shear stiffness appears to be associated with the bimodal distribution of electrons along the lengths of the C-C bonds. Also, for centrally directed interatomic forces, the ratio C44/C12is expected to be unity. But In diamond it is 4.6, indicating that the behavior of diamond cannot be described even approximately by pair-potentials. Because of its unique strength diamond can perform exceptionally in mechanical devices such as: pressure vessels, ultracentrifuges, springs, flywheels, and cutting (or drawing) tools.
Frictional Behavior of C60 Microparticle-Coated Steel
Authors: Zhao Wei , Tang Jinke , Purl Ashok , Falster Alexander U. , Simmons William B. 
Published: April 2011

ABSTRACTThe frictional behaviors of 304 stainless steel disks coated with C60 microparticles, both containing benzene and free of benzene, have been studied under different loads and sliding speeds with a pin-on-disk configuration in ambient air atmosphere at room temperature. The results indicated that the coating containing benzene, benzene-solvated C60 microparticles (C60·4C6H6), reduced friction as well as wear. The coated samples showed a 50–70% reduction in friction coefficient in comparison to uncoated samples. Neither the coated nor the uncoated sample showed significant change in friction coefficient for different sliding speeds. Under different loads, the uncoated sample had almost the same friction coefficient. However, with the increase of load, the friction coefficient of C60·4C6H6-coated disk showed a minimum value of 0.25 at 25 g load and then reached the uncoated values beyond 50 g load. The coefficient of friction of the disk coated with benzene-free C60 showed a slight increase with load, reaching the value of uncoated 304 stainless steel disk at about 40 g. The reduced friction of the solvated-C60 coated 304 stainless steel is probably due to the lowered shear strength of the hcp structure of C60·4C6H6 molecular crystal in which the benzene molecules are intercalated. The results of this study suggest the importance of the presence of second component, in addition to C60, in the coating materials in order for them to form a preferred crystal structure with low shear strength as far as using C60 as a solid lubricant is concerned.
Application of Ripple Pyrometry on Integra Rapid Thermal CVD Cluster Tools
Authors: Xing G. C. , Wang Z. H. , Schietinger C. , Wasserman Y. , Sun M. H. 
Published: April 2011

AbstractThis paper presents the application of ripple pyrometry on AG Associates Integra systems which are three phase powered and multi-zone controlled rapid thermal CVD cluster tools. Two types of sensor configurations were explored for optimum emissivity compensated temperature measurement performance. It was found that it is very difficult to measure temperature when a two sensor configuration is used due primarily to the chamber and reflector architecture. Good temperature measurement was obtained at high temperatures when zone ratios between the wafer and lamp sensors were aligned. It was also found that the temperature signal to noise ratio is very sensitive to ripple quality and zone ratio alignment accuracy.
Sub-Feature Speckle Interferometry: A New Approach To Temperature Measurement
Authors: Burckel D. , Zaidi S. H. , Brueck S. R. J. 
Published: April 2011

AbstractA new speckle technique, sub-feature speckle interferometry, is introduced that relies on the amplitude interference of two independent speckle patterns, originating from coherent illumination, using an optical system that produces interferometric quality interference fringes on a scale comparable to the speckle correlation length. Examples are given for in-plane translation, sample tilt, and temperature measurement (strain). A temperature measurement accuracy σ = 0.92°C is realized. In contrast to traditional full-field speckle cross-correlation techniques, this technique requires only a small number of detector elements with minimal signal processing and is compatible with many real-time sensor applications. Measurements of the optical phase across a speckle feature are presented.
Realistic Three-Dimensional Modeling Of Multizone Rapid Thermal Systems
Authors: Nagabushnam R. V. , Singh R. K. , Iyer R. , Sharan S. , Sandhu G. 
Published: April 2011

AbstractWe have developed a methodology aimed at accurately determining the various forms of energy transfer (convective loss, radiative loss and absorption of lamp energy by the wafer)occurring in any advanced RTP system, based on basic system identification experiments and simple 3-dimensional physical model depicting the heat transfer processes. The identification experiments help in estimating the uncertain system dependent factors which characterize the various forms of energy transfer, which may be otherwise difficult to calculate on pure theoretical basis. This methodology forms the basic building block of our effort to develop a tool which can predict the temperature distribution across the wafer in a realistic way. This tool can be used both as a wafer temperature control algorithm in any advanced RTP system as well as by an end user who is equipped with a not so advanced, but multizone, RTP system( the one with the user defined power levels to various zones).
The Merits of Integrated Processing for Gate Stack Formation
Authors: Grant John M. 
Published: April 2011

AbstractThis work presents the results of process development in a cluster tool designed for the gate stack process of cleaning, gate oxidation, and polysilicon chemical vapor deposition. The cluster tool connects three single wafer process chambers together with a vacuum transfer chamber. The purpose of this work was to test the feasibility of the single wafer processing gate oxidation cluster tool from an electrical performance standpoint, Cleaning was performed using a gas/vapor phase process, and the results using a standard oxide indicate that gas/vapor phase cleaning is at the least comperable and possibly more effective at contamination removal than the standard RCA wet cleaining process. The oxidation was performed using rapid thermal processing, and the effect of adding nitrogen to the oxide by oxidation in an N2O containing ambient was tested. The results indicated that oxides at least at good as those grown in a conventional furnace could be produced in the cluster tool, and the nitrogen at the oxide-substrate interface improves the reliability of the oxide if the nitrogen concentration is kept below 1 atomic %.
The Potential Effect of Multilayer Patterns on Temperature Uniformity During Rapid Thermal Processing
Authors: Hebb Jeffrey P. , Jensen Klavs F. , Egan Erik W. 
Published: April 2011

AbstractThis work aims to systematically gain an understanding of the effects of multilayer patterns on wafer temperature uniformity during rapid thermal processing, and explore possible solutions to the problem. Steady state and transient wafer temperature distributions are simulated by combining a detailed reactor transport model with multilayer electromagnetic theory to predict wafer radiative properties. A generic axisymmetric RTP system with single-side illumination is used as a testbed to explore pattern effects for a simulated source/drain implant anneal.
Rapid Thermal Epitaxy for Device Applications
Authors: King C. A. , Johnson R. W. , Chiu T. Y. , Sung J. M. , Mastrapasqua M. , Pinto M. R. 
Published: April 2011

AbstractRapid thermal epitaxy (RTE) is studied for a variety of applications including transistors as well as optoelectronic devices. Two transistor applications are discussed here. First, the growth of n-type epitaxial layers over n+ buried layers for low power BiCMOS, and second, the growth and fabrication of charge injection transistors (CHINTs) from a multi-layer structure including strained Si1−xGex layers.Scaled bipolar transistors for BiCMOS integrated circuits require low collector-substrate capacitance in order to minimize power consumption. The unintentional incorporation of dopant into a growing epitaxial layer, known as autodoping, can affect the ultimate lower limit of the collector-substrate capacitance. In this work, we studied the effects of epitaxial layer growth rate, arsenic buried layer implant dose, and pre-epitaxial bake temperature on autodoping using RTE. To begin, we experimented with the buried layer implant dose to check its affect on lateral autodoping. The amount of autodoping increased when the buried layer implant dose increased, confirming the source of the arsenic autodoping as the buried layer. Also, in contrast to data from conventional reactors, we found the peak interface concentration and integrated dose in regions adjacent to the buried layer to be linearly dependent on the growth rate (i.e. low growth rates trap less arsenic at the substrate/epi layer interface). Next, by adjusting the pre-bake temperature over a range from 800 to 1050°C without changing the growth conditions, we first observed a rise in autodoping with temperature to 950°C at which point the incorporated autodoping dose and peak concentration began to fall. Through simulation of the evaporated arsenic from the buried layer and data for arsenic desorption from the silicon surface, we explain this behavior. Finally, using the data gathered on the autodoping characteristics of RTE, we show a process using two growth rate steps and a low temperature pre-bake step which completely eliminates the lateral autodoping peak. Using this new growth process, epitaxial silicon films over arsenic doped buried layers for low power BiCMOS are possible.Charge injection transistors and logic elements have been successfully implemented in a Si/Si0.7Ge0.3 heterostructure grown by RTE on a Si substrate. Shallow p+ source and drain ohmic contacts are obtained by a boron diffusion from a selectively deposited boron doped Ge layer. Room temperature operation of the charge injection transistor is demonstrated for the first time. High frequency measurements indicate a short circuit current gain cutoff frequency of 6 GHz.
Tisi2 Characterization of CVD-Titanium and RTP on a Cluster Platform–an Initial Investigation
Authors: Marcus Steven D. , Deutschmann Lutz 
Published: April 2011

AbstractThe silicidation of chemical vapor deposited (CVD) titanium has been investigated utilizing the Materials Research Corporation (MRC) PHOENIX™ cluster-tool platform which incorporated an AST elektronik GmbH cluster RTP chamber. This initial investigation focuses on C49 and C54 TiSi2 phase formation on bare silicon wafers. Equipment description, process results, comparison to classical PVD Ti silicide processing and future investigations will be presented.
Concurrent Design of an RTP Chamber and Advanced control system
Authors: Spence Paul , Schaper Charles , Kermani Ahmad 
Published: April 2011

AbstractA concurrent-engineering approach is applied to the development of an axisymmetric rapidthermal- processing (RTP) reactor and its associated temperature controller. Using a detailed finite-element thermal model as a surrogate for actual hardware, we have developed and tested a multiinput multi-output (MIMO) controller. Closed-loop simulations are performed by linking the control algorithm with the finite-element code. Simulations show that good temperature uniformity is maintained on the wafer during both steady and transient conditions. A numerical study shows the effect of ramp rate, feedback gain, sensor placement, and wafer-emissivity patterns on system performance.
Mechanisms of Grain Growth in Bubble-Fence-Delineated Films
Authors: Townsend S. J. , Frost H. J. , Nichols C. S. 
Published: April 2011

ABSTRACTThe strength of polycrystalline metallic films at high temperatures is limited by grain boundaries. Boundaries transverse to the film surfaces typically fail by decohesion, while boundaries parallel to the film surfaces are susceptible to sliding. In light of these facts, multilayer films are now being made that resemble stacks of columnar-grained thin films[l]. Nearly planar arrays of insoluble bubbles, called "bubble fences," maintain the integrity of the individual layers by pinning the interlayer boundaries. However, the transverse boundaries that delimit the columnar grains within an individual layer are able to move. Processing aims to produce a highly-overlapping microstructure that isolates the weak-link transverse boundaries and increases the material's time-to-failure. In potassium-doped tungsten this strategy is an extension of current lamp filament technology.We have studied the mechanisms of grain growth within the grain layers in order to provide a basis for improving the synthesis and processing of these materials. For this type of grain growth to occur, the boundaries between grain layers must remain pinned by the bubble fences. Theory and 3D Evolver[2] simulations of a simple model provide a possible explanation for the depinning seen in recent experiments[3]. Reducing the ratio of intra-fence bubble separation to bubble diameter is predicted to eliminate the depinning. Ongoing study of a complete 3D model will further aid in tuning the synthesis and processing to create grain architectures with superior high-temperature properties.
Molecular Dynamics Simulation of Mechanical Deformation of Ultra-Thin Metal and Ceramic Films
Authors: Belak J. , Glosli J.N. , Boercker D.B. , Stowers I.F. 
Published: April 2011

ABSTRACTWe present an overview of the molecular dynamics computer simulation method as employed in the study of the mechanical properties of surfaces at the nanometer scale. The embedded atom method is used to model a clean metal surface and the bond-order model is used to model ceramic surfaces. The computer experiment consists of the indentation and scraping of a hard diamond-like tool into and across the surface. Results are presented for the (111) surface of copper and silver and for the (100) surface of silicon. We explicitly demonstrate in our point indentation simulations that nanoscale plasticity in metals takes place by nondislocation mechanisms, a result suggested by recent nanoindentation experiments. We also observe the surface to accommodate nearly the entire volume of the tip and the annealing out of plastic work as the tip is removed. In our orthogonal cutting simulation, we observe an interesting phenomenon: the system dynamically reorients the grain in front of the tool tip to minimize the work performed on the shear plane (i.e. the shear plane becomes an easy slip plane). Silicon transforms into an amorphous state which then flows plastically.
Modeling and Computer Simulation of the Thermal Field Induced by Ion Beam Irradiation of Bilayers
Authors: Sebastiano Tosto 
Published: April 2011

ABSTRACTA 3D analytical model of calculation has been carried out to simulate the heat effects induced during ion beam assisted thin film deposition. The irradiation conditions enabling the growth of the film under steady conditions of temperature are discussed. Some results are presented to show the computer simulation of possible surface processing conditions.
Comparison of Damage Accumulation Models for Boron Implantation in Silicon
Authors: Simionescu A. , Hobler G. 
Published: April 2011

ABSTRACTTwo models of damage accumulation during boron implantation are compared: The first one analyzes the full collision cascades and lets vacancies and interstitials recombine, if they are located within some capture radius of each other. The second one uses a constant fraction of defects surviving damage annihilation within a recoil cascade and a damage saturation density to take into account recombination with defects generated in previous cascades. While the first model is more fundamental, the second one is computationally more efficient. By comparing model predictions with 20 keV boron implantations at various doses, performed into (100) and (110) silicon with 7° and 0°, respectively, we conclude that different capture radii have to be used for damage annihilation within the recoil cascades and with defects generated in previous cascades. Moreover, we show that the two models are almost equivalent, if appropriate parameters are chosen. Recombination factors determined from simulations using a capture radius are almost independent of depth and implantation energy.
The Effects of Collimator Life Time on the Ti and Tin Film Growth Rates and Conformalities in Sputter Deposition Processes: Experiments and Simulations
Authors: Liao Hung , Stippel Hannes , Reddy Krishna , Geha Sam , Brown Kevin , Lindorfer Philipp , Saha Samar , Lin Zhou , Cale Timothy 
Published: April 2011

ABSTRACTExperimental and simulation studies were conducted in an attempt to understand the effects of collimator life time on the Ti and TiN film growth rates and conformalities in sputter deposition processes. The Ti and TiN films were deposited with and without collimation. The hexagonal cells of the collimator used in this study have a 1:1 aspect ratio. A Monte Carlo based simulator was used to calculate the angular distributions of species exiting from a collimator cell and the percentage decrease in the rate of film growth as a function of the collimator life time. Then, a low pressure deposition process simulator, EVOLVE, was used to predict the conformalities of deposited films in contacts or vias, assuming that the films were uniformly deposited on the side-walls of collimator cells. We conclude that the loss in growth rate is largely due to the shrinkage in the cross sectional area of the collimator cell inlets. We arrive at this conclusion after comparing an estimated film thickness on the collimator side-walls with experimental measurements. With extended collimator usage, the predicted and experimental film profiles in contacts or vias show increasing bottom coverage and decreasing side-wall coverages.
Optimization of Process Parameter and Temperature Uniformity on Wafers for Rapid Thermal Processing
Authors: Tillmann Andreas 
Published: April 2011

ABSTRACTA new strategy based algorithm to optimize process parameter uniformity (e.g. sheet resistance, oxide thickness) and temperature uniformity on wafers in a commercially available Rapid Thermal Processing (RTP) system with independent lamp control is described. The computational algorithm uses an effective strategy to minimize the standard deviation of the considered parameter distribution. It is based on simulation software which is able to calculate the temperature and resulting parameter distribution on the wafer for a given lamp correction table. A cyclical variation of the correction values of all lamps is done while minimizing the standard deviation of the considered process parameter. After the input of experimentally obtained wafer maps the optimization can be done within a few minutes. This technique is an effective tool for the process engineer to use to quickly optimize the homogeneity of the RTP tool for particular process requirements. The methodology will be shown on the basis of three typical RTP applications (Rapid Thermal Oxidation, Titanium Silicidation and Implant Annealing). The impact of variations of correction values for single lamps on the resulting process uniformity for different applications will be discussed.
Properties of Point-Defects in Si for Process Modeling
Authors: Gossmann H.-J. , Rafferty C. S. , Stolk P. A. , Eaglesham D. J. , Gilmer G. H. , Poate J. M. , Vuong H.-H. , Mogi T.K. , Thompson M. O. 
Published: April 2011

ABSTRACTThe development of future Si device technologies will rely extensively on modeling, requiring truly predictive tools. Here we focus on the front-end processes, during which ion-implantation and annealing create 3-D impurity profiles that determine crucial electrical device parameters. The final configuration is the result of a complex interaction of dopant atoms with Si self-interstitials and vacancies, which themselves interact with each other as well as with the implantation-induced damage and interfaces. Predictive modeling requires for all these processes a solid understanding of the physical phenomena as well as accurate quantitative information. Si self-interstitials and vacancies are not observable directly in an experiment, but only via their interactions with some other physical quantity of the sample. We review our work employing dopant atoms in δ-doping superlattices (δ-DSL) that yield directly the time averaged depth profiles of Si native point defects during a particular processing sequence. This approach is uniquely suited for giving insights into the interplay of point defects in Si, providing crosschecks for atomistic calculations as well as parameters for process simulators. We describe experiments to extract interstitial and vacancy parameters and discuss the influence of intrinsic and extrinsic interstitial traps, as well as of the annealing environment, on the native point defect population. The latter allows to place certain bounds on the interstitial vacancy recombination coefficient as well as the ratio of interstitial and vacancy equilibrium concentrations.
Application of a Neural Manufacturing Concept to Process Modeling, Monitoring and Control
Authors: Fu Chi Yung , Petrich Loren , Law Benjamin 
Published: April 2011

ABSTRACTThe cost of a fabrication line, such as one in a semiconductor house, has increased dramatically over the years, and it is possibly already past the point that some new start-up company can have sufficient capital to build a new fabrication line. Such capital-intensive manufacturing needs better utilization of resources and management of equipment to maximize its productivity. In order to maximize the return from such a capital-intensive manufacturing line, we need to work on the following: 1) increasing the yield, 2) enhancing the flexibility of the fabrication line, 3) improving quality, and finally 4) minimizing the down time of the processing equipment. Because of the significant advances now made in the fields of artificial neural networks, fuzzy logic, machine learning and genetic algorithms, we advocate the use of these new tools in manufacturing. We term the applications to manufacturing of these and other such tools that mimic human intelligence neural manufacturing. This paper describes the effort at the Lawrence Livermore National Laboratory (LLNL) [1] to use artificial neural networks to address certain semiconductor process modeling, monitoring and control questions.*