bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metal Surface Morphology Characterization Using Laser Scatterometry
Authors: Gaspar S. M. , Hickman K. C. , McNeil J. R. , Jacobson R. D. , Lindauer G. P. , Strausser Y. E. , Krosche E. R. 
Published: March 2011

ABSTRACTWe have applied angle-resolved laser scatterometry to characterize the morphology of metals deposited under various conditions. Scatterometry is a rapid, noncontact and nondestructive diagnostic which yields surface statistics including rms roughness and power spectral density of the microstructure.
The Effect of Chemical Treatment of the GaAs Surface on the Ohmic Contact Properties
Authors: Kovács Balázs , Németh-Sallay Margit , Mojzes Imre 
Published: March 2011

ABSTRACTElectrical properties of metal/GaAs system are known to be influenced very much by GaAs surface condition before the metal deposition. The surface condition of GaAs epitaxial layer can be affected by the wet chemical treatment of the surface. The influence of different processes were compared to choose the best technique for a high quality ohmic contact technology. Applying a chemical treatment which contains degreasing process, a light surface etching and a rinsing process, the carbon contaminations, 20-25 nm GaAs surface layer and the native oxide layer are removed from the GaAs surface. The benefit of the rinsing step is to produce a reproducible, stable surface condition before the metallization. Since the importance of the finishing step was assumed, the investigated processes differed in this step. The compared methods finished with either alkaline, like NH4OH, or acidic, like HCl, etchants resulted higher specific contact resistance than the process finished with neutral, high purity (18 MΩcm) water. In the latest case the obtained specific contact resistance was (6.4 ± 2.7) ×10−6 Ωcm2 on a GaAs epitaxial layer with the doping concentration 1.5 × 1017cm−3.
Parameters Affecting the Process Window for Laser Planarization of Aluminum.
Authors: Raaijmakers Ivo J , Chu Harren , Ong Edith , Wang Shi-Qing , Ritz Ken 
Published: March 2011

ABSTRACTIrradiation with excimer laser pulses is demonstrated as a technique to fill contact/via holes for integrated circuits with Al-(1 wt.%)Cu. We discussed the influence of the size, shape and aspect ratio of the contact hole, and the metal thickness on the process (attitude for laser planarization. The most dominant parameters found to influence the planariza-tion process are the shape of the contact, and the shape of the as-deposited metal surface (“step coverage”). The application of a Cu anti-reflection coating increased the process window substantially. Although a planar Al-Cu surface was easily formed with laser irradiation, void free filling of contact holes was a more demanding task. Conditions for which completely filled contacts can be obtained were discussed.
Interface Morphology, Nucleation and Island Formation of Tisi2 on Si(111).
Authors: Jeon Hyeongtag , Sukow C. A. , Honeycutt J. W. , Humphreys T. P. , Nemanich R. J. , Rozgonyi G. A. 
Published: March 2011

ABSTRACTIn this study we investigate the formation mechanisms and morphology of TiSi2 formed by deposition of Ti on atomically clean silicon substrates. Ti films of 50–400 Å thickness were deposited in ultra-high vacuum on Si (111) wafers and annealed to temperatures between 500–900°C. Films were monitored in situ with AES and LEED, and post preparation characterization was accomplished with SEM, TEM and Raman scattering. The results show that for films of thickness ≤, 100 Å the C49 TiSi2 phase is stable over the entire 600-800°C temperature range. However, for films of 200-400 Å thickness, the C49 to C54 phase transition occurs at temperatures varying from 700 to 800°C dependent upon film thickness. The high temperature annealing results in flat interface structures, and island formation is observed for all films with the C54 structure. The interface morphology and the mechanisms of TiSi2 island and phase formation are discussed in terms of surface and bulk free energies considerations based on nucleation theory.
Structural and Substructural Analysis of Glass Surface
Authors: BochyŃskia Zenon 
Published: March 2011

ABSTRACTA structure of surface and near surface layers in inorganic glasses used as substrated in metallization was studied. The analysed samples were made of melted quartz, technical and optical quartz glass and sodium-silicate glass.The sample surface were at first treated mechanically ground and polished and then chemically etched.In the investigation we applied the following methods:- X-ray and electron/mean voltages 35…65 kV/diffraction,- electron emission microscopy,- optical/UV-VIS/and infrared/IR/microspectrophotometry and microscopy.For the studied series of quartz based/SiO2/glasses we determined the size of inhomogeneous. regions and the distortion degree of the elementary tetrahedra/basic structural elements/and estimated the thickness of surface and near-surfaoe layers.The obtained structural parameters enabled us to propose structural models of the surface of real glasses uaed in elec-trotechnology, electronics and microelectronics.
Low Resistance α-Ta Film For Large Area Electronic Devices
Authors: Yamamoto Shigeru , Hikichi Takehito , Hamano Toshihisa 
Published: March 2011

ABSTRACTA New method of the low resistivity α-Ta deposition technique has been developed. The sputtered Ta film deposited on TaMo alloy has bcc structure (α-Ta) in contrast to tetragonal of the Ta mono layer (β-Ta), and shows the resistivity as low as 22μΩ cm. The mechanism of this transformation is not explained by simple epitaxial growth. X-ray diffraction analysis and RBS analysis indicated that the TaMo alloy layer, due to Mo diffusion from the under layer, acts as a seed plane of growth. The Ta/TaMo layered film is suitable for Large Area Electronic devices for its low resistivity.
Properties of Laser Planarized Aluminum Alloy Films
Authors: Ramaswami Seshadri , Smith Jonathan 
Published: March 2011

ABSTRACTAn excimer laser (XeCl, 308 nm) has been used to locally melt and reflow aluminum alloy films into contacts of VLSI device structures resulting in contact filling and local planarization. This technique has the potential to be the answer to the ‘poof’ aluminum step coverage problem. The first order problems are that of ablation and voids. Voids have been categorised as ‘line voids’ and ‘contact voids’. Various processing conditions of the barrier, Al-Si-Cu alloy and Al-Cu alloy metallizations were explored to obtain the optimum process with the desired film characteristics.
Effects of Dwell Time and Current Density on Ion-Induced Deposition of Tungsten
Authors: Tran Khanh Q. , Madokoro Yuuichi , Ishitani Tohru , Yang Cary Y. 
Published: March 2011

ABSTRACT30-keV focused Ga+ ion beam was used for induced deposition of small-area tungsten thin films from W(CO)6 on Si and SiO2. Deposition yield, calculated assuming pure tungsten depositions, depends on dwell time (beam diameter/scan speed) and beam current density. High current density and/or long dwell time are known to cause low deposition yield because of the depletion of adsorbed gas molecules during ion beam irradiation. Based on a model taking this effect into account, numerical fitting was carried out. The reaction cross-section was estimated to be 1.4 × 10−14 cm2. For doses below 1017 ions/cm2, film resistivity decreases with increasing dose. This was confirmed for several dwell times. However, for doses above 1017 ions/cm2, film resistivity remains independent of dose. In this “high”-dose range, variation of beam current density has little effect on film resistivity. AES analyses revealed a consistency between film composition and resistivity. For a “high”-dose film with a resistivity of 190 μΩ-cm, the approximate tungsten content was 50 at%.
Low Temperature Tungsten Deposition by Arf-Laser Induced Photo-CVD
Authors: Krans Rutger L. , Berntsen Arjan , Sinke Wim C. 
Published: March 2011

ABSTRACTLaser-induced Chemical Vapor Deposition of tungsten on Si(100) using WF6 and H2 has been investigated using a high-vacuum system comprising a cold-wall reactor. The activation source is a pulsed ArF-excimer laser. The deposition rate depends linearly on the repetition rate, when H2 is used as a reducing agent. When no H2 is used the laser radiation suppresses deposition.At deposition temperatures down to 200 °C laser deposited layers have resistivities better than 20 μΩ cm. Thick layers have resistivities down to 8 μΩ cm. There is a direct relation between layer thickness and resistivity. X-ray diffraction revealed the layers to consist of α-tungsten. β-tungsten was only obtained for those thermally deposited layers where growth was slower than expected.Nuclear reaction analysis of fluorine showed that most fluorine is present near the W-Si interface, and that the amount of fluorine relative to the amount of tungsten in the layer decreases markedly with deposition temperature.
Modified Line-of-Sight Model for Deposition of Tungsten Silicide Barrier Layers
Authors: Cale Timothy S. , Raupp Gregory B. 
Published: March 2011

ABSTRACTA modified line-of-sight model for transport and deposition during LPCVD is used to predict step coverage and film composition uniformity of tungsten silicide barrier layers. Predictions are compared with experimental results for 2 μim wide by 6 μm deep trenches with barrier layers of 0.2 μm nominal thickness. Model predictions are in quantitative agreement with those of a diffusion-reaction model and are in qualitative agreement with experiment.
Deposition Mechanism of Tungsten Silicide Films by Low Pressure CVD
Authors: Sone Jae H. , Kim Hyeong J. 
Published: March 2011

ABSTRACTWSix thin films were deposited on SiO2/Si substrates by Low Pressure Chemical Vapor Deposition (LPCVD) using WF6 and SiH4 gases. The deposition mechanism has been studied by measuring the thickness, resistivity and composition of the films by varying deposition temperature and gas flow rate at a constant total reactant gas pressure. Below 300°C, the surface chemical reaction was the rate-limiting process and the deposition rate increased exponentially with temperature having a thermal activation energy of 3.2 kcal/mol. Meanwhile, above 300°C the reaction was governed by the mass transfer step in the gas. The deposition rate in this range is insensitive to the deposition temperature but shows dependence of the flow rate of reactant gases. AES and RBS analyses were performed to determine the stoichiometry of WSix thin film. The Si content in film gradually increased as the deposition temperature increased. The resistivity of as-deposited WSix film has dependence on both deposition temperature and Si/W ratio, and exponentially increased with a moderate slope. However, temperature insensitive behavior of resistivity appeared in the mass transfer controlled region. Such resistivity changes with temperature were discussed with the Si/W ratio and the microstructure of films.
Chemical Vapor Deposition of Copper from an Organometallic Source
Authors: Beach David B. , Kane William F. , Legoues Francoise K. , Knors Christopher J. 
Published: March 2011

ABSTRACTHigh purity copper has been deposited from trialkyl phosphine complexes of cyclopentadienyl and methylcyclopentadienyl copper(I) by thermal chemical vapor deposition (CVD). Films as thick as 4.4 μm have been deposited at growth rates of up to 2000 Å/min with resistivites typically 2.0 μΩ cm, just slightly higher than bulk copper. Depositions were carried out at substrate temperatures between 150 and 220 °C on a variety of substrates including Si, SiO2, polyimide, and Cr/Cu. At low substrate temperatures, copper film growth appears to show some selectivity for transition metal surfaces. An activation energy of 18 kcal/mole has been measured for film growth on Cu seeded substrates. CVD copper films have been characterized by Auger spectroscopy which showed that carbon and oxygen levels are below the limits of detection. Transmission electron microscopy revealed that the copper grain size was ∼0.6μm and the grain boundaries are free of precipitates. Films show good conformality.
In-Situ Transmission Electron Microscopy of the Formation of Metal-Semiconductor Contacts
Authors: Gibson J. M. , Loretto D. , Cherns D. 
Published: March 2011

ABSTRACTWe have studied the formation of metal silicides in-situ in an ultra-high vacuum transmission electron microscope. Metals were deposited on in-situ cleaned, reconstructed silicon surfaces and annealed. For the metals Ni and Co, we find that the phase sequence in ultra-thin films is different from that seen in ≈1000 Å thick films, and attribute this to the high surface-to-volume ratio. In general reactions occur at room temperature, to form an epitaxial phase if possible. We report preliminary new results on the formation of Pd2Si.
Formation of Cobalt Silicides in Arsenic Implanted Cobalt on Silicon System
Authors: Sitaram A.R. , Murarka S.P. 
Published: March 2011

ABSTRACTThe importance of self aligned cobalt disilicide technology for gate and interconnection, and contact metallization cannot be overemphasized. Simultaneously, the concept of forming shallow junctions by using the metal or silicide layer as a dopant source is gaining prominence. In this work, we will present and discuss the results of the effect of arsenic, implanted into cobalt films on silicon, on the Co-Si reaction. Arsenic redistribution during the reaction, both during furnace annealing and RTA, and the effect of ion implantation and dose and energy will also be included.
Luminescence of Alizarin and its Metal Complexes
Authors: Larson Londa J. , Zink Jeffrey I. 
Published: March 2011

AbstractThe red/near-infrared emission spectra of alizarin (1,2-dihydroxyanthraquinonone), the potassium salt of alizarin and the aluminum and zinc complexes of alizarin in the solid state are reported. The emission is assigned to an alizarin localized transition from an in-plane nonbonding orbital delocalized over the anthraquinone rings to a predominantly π* C=O acceptor orbital (nπ* ligand localized excited state). The cobalt, nickel and copper complexes do not emit from their nπ* excited state. In these complexes, metal centered d-d excited states which lie lower in energy than the ligand localized state effectively deactivate the luminescence.
Applications of Environmental Scanning Electron Microscopy in Art Conservation and Archaeology
Authors: Stulik Dusan , Doehne Eric 
Published: March 2011

AbstractThe principles of Environmental Scanning Electron Microscopy (E-SEM) are explained and discussed. The performance of the E-SEM compares favorably with the performance of traditional SEM instruments. This new technology has significant advantages in art conservation and archaeology. In this paper we describe several pilot studies which explored potential uses of the E-SEM. Electron micrographs recorded from moist, outgassing, and difficult to coat samples are presented, together with X-ray spectra recorded from uncoated samples of electrically nonconductive materials.
Glass-Sensors: Assessment of Complex Corrosive Stresses in Conservation Research
Authors: Fuchs Dieter R. , RÖmich Hannelore , Schmidt Helmut 
Published: March 2011

AbstractGlass sensors, based on K-Ca-silicate glass chips, with a low durability against corrosive stresses, offer a new method for assessing the complex environmental stress situation of monuments and pieces of art. The easy-tohandle technique is able to detect the combined impact of climatic stresses, pollution and microbiological effects as well as synergetic interactions.The chemical composition of the sensitive glasses enables judgements within few months. This way long-term estimates can be obtained without costly long-term investigations.The corrosion progress is determined by microscopy and IR-spectroscopy of the weathered glass sensor surfaces. The sensors are already operating in the field of stained glass window preservation. They monitor the efficiency of different kinds of external protective glazings and the remaining stresses from the in-door environment of cathedrals.
Evaluation in Situ of the State of Deterioration of Monumental Stones by Non-Destructive Ultrasonic Techniques.
Authors: Montoto M. , Calleja L. , Perez B. , Esbert R.M. 
Published: March 2011

AbstractA non-destructive ultrasonic procedure has been developed for evaluating in-situ the relative deterioration of monumental stones. Ultrasonic waves are injected into the rock and they are registered, processed and petrophysically interpreted after travelling through it. The procedure applied to a Spanish Monastery (San Lorenzo de El Escorial, Madrid) built with a granitic rock is described.The following methodology was applied: in-situ categorization of the observable deterioration forms, sampling in the original quarries, laboratory ageing tests and continuous ultrasonic monitoring, in-situ data acquisition, evaluation of the ultrasonic parameters by signal processing and stepwise discriminant analysis. All that information is petrophysically interpreted for an appropriate assignation of the in-situ studied masonry blocks to the categorized deterioration degrees.Final in-situ results from the Monastery of El Escorial are here presented. Among the studied ultrasonic parameters energy is the most useful of all of them and velocity the least.
Mechanical Stresses Generated by Crystallization of Salts Inside Treated and Non-Treated Monumental Stones; Monitoring and Interpretation by Acoustic Emission / Microseismic Activity.
Authors: Esbert R.M. , Montoto M. , Río L. M. Suárez Del , Argandoña V. G. Ruiz De , Grossi C.M. 
Published: March 2011

AbstractThe crystallization of salts in building stones is one of the most common and severe deteriorating phenomencndeveloped on Historic Buildings. To evaluate their mechanical effects in treated and non-treated stones, experimental salt crystallization tests and the monitoring of the corresponding acoustic emission / microseismic activity, AE/MS, have been planned.Salt crystallization tests have therefore been performed on a high porosity (30%) limestone used in the building of the Cathedral of Murcia (Spain). Each test consisted of 11 and 20 cycles (for the non-treated and treated specimens, respectively) of immersion of specimens in salt solution (14% Na2SO4. 10H2O) for 4 h., drying in an oven at 60 °C for 14 h. and final cooling at room temperature for 6 h. The treated specimens were consolidated by total immersion in ethyl silicate -Tegovakon V- and protected with a water repellent, oligomeric polysiloxane -Tegosivin HL- 100-, (both from Th. Goldschmidt, FRG).The AE/MS, was monitored in the 100-300 KHz range. The preliminary results show a very different AE/MS behaviour between the non-treated and the treated specimens.
Technology and Weathering of Mesoamerican Jades as Guides to Authenticity
Authors: Garza-Valdes Leoncio A. 
Published: March 2011

AbstractThe beauty of a carved pre-Columbian jade defies description. Unfortunately, thousands of fake jade pieces are in museums and private collections. In the study of authenticity, it is necessary to scientifically analyze the surface, observing the changes produced by reactions with the environment, mostly aqueous soil mixtures.
The Critical Role of Technological Analysis for Prehistoric Anthropological Inference
Authors: Rollefson Gary O. 
Published: March 2011

AbstractPrehistoric archaeology has profited enormously from the expanding role of technological examination of artifactual materials, particularly in the past couple of decades. Indeed, the rapid growth of materials sciences studies has evidently begun to outpace the capacity of many prejistoric archaeologists to accomodate the results of technological analyses into anthropological models to explain perceived changes in the prehistoric archaeological record. The sheer numbers of published technological reports, which increasingly appear in a growing number of specialized journals and other publications, account for some of the communications lag among prehistorians and smaterials scientists. But long-held and persistent myths and “hearsay” evidence also contribute to a widening gap between relevant data and critical evaluation.The case study presented below compares scenarios that purport to explain striking contrasts in the northern and southern parts of the Levant during the middle part of the Neolithic period, particularly from ca. 6,500-5,000 b.c. One hypothesis (climatic change) is briefly dismissed; the other hinges principally on the environmental implications of plaster production that characterized the cultures of the region. The “collapse” of the southern Levantine settlements is understandable when the specific requirements of lime plaster manufacture are taken into account, while the conditions for the persistence of long-term site continuity in the northern Levant are clear under the less pressing environmental demands of gypsum plaster production.
Ancient High-Strength Ceramics: Fritted Faience Bracelet Manufacture at Harappa (Pakistan), Ca. 2300-1800 B.C.
Authors: McCarthy Blythe , Vandiver Pamela 
Published: March 2011

AbstractUnlike most ancient faience, which consists of a quite porous and weak body coated with a glassy glaze, much Harappan faience has a quite dense body with a continuous glassy phase and a relatively thin skin of glaze. A multiple-step grinding and fritting process of manufacture was used to make the finely ground, uniformly blue-green and other colored bodies. Intentional additions of glass frit and clay are postulated. The Harappan faience bodies are particularly strong, compared with contemporaneous faience from Southwest Asia and Egypt, because Harappan faience is more dense, because differential thermal contraction during cooling places the continuous glassy phase in compression, and perhaps also due to crack deflection toughening. A similar technology is not found in Egypt until much later during the New Kingdom about 1450 B.C., and then only glass is added.The socio-cultural reasons for the development of such a specialized technology probably resides in the properties required of the particular type of artifact in which this technology is most often found, that is, bracelets. Bracelets, or bangles, were worn on arms and legs; most often several were worn at a time. Such use required the bracelets to meet criteria of increased abrasion resistance and impact strength, and thus an innovative technology was developed to meet these needs.
Accelerator Radiocarbon Measurements of Artistic Artifacts
Authors: Donahue D. J. , Jull A. J. T. , Toolin L. J. , Barnhill J. , Lange T. 
Published: March 2011

AbstractThe use of a particle accelerator to measure the 14C content of carbon-containing materials is briefly described. The application of the method to the determination of the age of some artistic artifacts is discussed.
The Reconstructiton of Ancient Ceramic Technology Through the Comparative Analysis of Ancient and Contemporary Potters′ Materials: A Case Study from the Central Tiber Valley of Italy
Authors: Peña J. Theodore 
Published: March 2011

AbstractThis paper presents the results of a program of mineralogical analysis aimed at the elucidation of raw material acquisition and paste preparation practices among Roman-period potters in the Orte/Vasanello area of the central Tiber Valley of Italy. A study of modern folk potters at Vasanello revealed a complex pattern of clay utilization. A selection of local clays, pottery produced by Vasanello potters, and ceramics from two Roman ceramic production sites was subjected to mineralogical analysis (x-ray diffraction, petrographic) for purposes of comparison. The results indicate that similar clay sources were exploited by potters in both periods, and that the materials obtained from these were likely employed for similar functional varieties of pottery.