bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrated Titanium Silicide Processing
Authors: Nulman Jaim 
Published: March 2011

ABSTRACTThe processing of titanium silicide in a multichamber processing system is described. Three processes are included: wafer cleaning, Ti deposition, and annealing. The results are compared to wafers processed in a conventional way with exposure to ambient air between Ti deposition and the annealing step. TEM, RBS and sheet resistance measurements indicate that the films processed without exposure to ambient air have thicker and purer TiN layers as compared to the films with air exposure. Furthermore, integration allows for a wider processing window for the first annealing step. The use of reactive cleaning chemistry prior to Ti deposition results in a smooth silicon surface and therefore uniform silicidation as compared to inert cleaning technology, where redeposit of etched material occurs.
Geometrical effects and disintegration of narrow TiSi2/poly-Si lines
Authors: Norström H. , Maex K. , Vandenabeele P. 
Published: March 2011

ABSTRACTThe geometrical shape and the thermal stability of the TiSi2/poly-Si interface on narrow lines has been studied. The examined line-widths varied between 0.8 μm and 1.5 μm. The thermal stability was found to strongly correlate to the actual line-width of the structures. At the onset of degradation, at and above 900°C, narrow lines were observed to disintegrate at a much faster rate than wider ones. Cross-sectional microscopy (TEM and SEM) revealed the TiSi2/poly-Si interface to be curved inwards. The interface bowing was found to be more pronounced on narrow lines. It is suggested that the interface bowing results from a mechanical pinning of the TiSi2/poly-Si interface by the side-wall spacers.
Cobalt Silicide Formation on Polysilicon: Dopant Effects on Reaction Kinetics and Silicide Properties
Authors: Sitaram A. R. , Murarka S. P. 
Published: March 2011

ABSTRACTThe concept of using cobalt disilicide as a self-aligned metallization scheme for gate/interconnection and contact formation is gaining wide acceptance. The silicide formation on the gate will require a Co-metal film interaction with the underlying polysilicon that may be doped heavily. We have investigated the silicide formation kinetics during this reaction. The effect of different dopants (B,P, and As) and their concentration on the Co-Si interaction and the dopant redistribution during such reactions were investigated. The results from these studies will be presented and discussed.
Reliable Metallization For InP-Based Devices and Oeic’s
Authors: Wada O. , Ueda O. 
Published: March 2011

ABSTRACTWe describe techniques of reliable metallization in InP-based systems for application to discrete and opto-electronic integrated circuits (OEIC’s). Strong metallurgical interaction between Au and InP-based compounds can cause serious contact degradation in light emitting diodes (LED’s). By analyzing this interaction in detail, an improved thin Au/Zn/Au p-contact technique has been developed. The results are compared with Pt/Ti contacts, and it has shown that both provide sufficient reliability under temperature and current stresses in LED’s. We then describe a metallization technique for flip-chip bonding of opto-electronic devices on other semiconductor chips for OEIC applications. An acceptable reaction barrier effect of Pt in AuSn/Pt/Ti metallization structure has been demonstrated and this structure has been used for a high-reliability, flip-chip integrated GalnAs/InP PIN photodiode/GaAs amplifier receiver circuit. We also discuss requirements for metallization for future monolithic OEIC’s by taking up an example of metal-semiconductor-metal photodiodes in InP-based systems.
Reliability of Ohmic Contacts for AlGaAs/GaAs HBTs
Authors: Jackson G. S. , Tong E. , Saledas P. , Kazior T. E. , Sprague R. , Brooks R. C. , Hsieh K. C. 
Published: March 2011

ABSTRACTThe reliability of ohmic contacts to thin, heavily doped layers of GaAs is investigated. Pd/Ge/Au contacts to n-type GaAs display excellent electrical stability over extended periods of thermal stress. The contact resistance stays below 0.5Ω-mm during a 2500h, 280°C bake. Reactive ion beam assisted evaporation of Ti with N forms TiN which is introduced as a barrier layer in Pt/TiN/Ti/Au contacts to a thin p+ layer. The TiN layer allows greater process latitude in the sintering process and improves long term stability of the ohmic contact. The microstructure of the p-type contacts is examined with TEM and Auger profiling at different instances of the 2500h, 280°C bake and compared to the contact resistance measurements.
Applications of Amorphous Ti-P-N Diffusion Barriers in Silicon Metallization
Authors: Kolawa E. , Halperin L. , Pokela P. , Vu Quat T , Nieh C. W. 
Published: March 2011

ABSTRACTThin films of amorphous TiP and TiPN2 alloys were deposited by sputtering of a TiP target in an Ar and N2/Ar mixture, respectively. These alloy films were tested as diffusion barriers between Al and Si as well as between Cu and Si and also in metallizations which included TiSi2 as the contacting layer. Rutherford backscattering spectrometry, x-ray diffraction and electrical measurements were used to determine the barrier effectiveness. We find that TiP and TiPN2 films prevent the interdiffusion and reaction between Al and Si up to 500°C and 600°C for 30 minutes annealing, respectively, and between Cu and Si up to 600°C and 700°C, respectively.
Thermodynamic Stability of Ptal Thin Films on GaAs
Authors: Ko Dae-Hong , Sinclair Robert 
Published: March 2011

ABSTRACTThe thermal stability of PtAl thin films on GaAs substrates has been studied using transmission electron microscopy and Auger electron spectroscopy. The PtAl thin films were formed by sequential deposition of discrete Pt and Al layers on GaAs by e-beam evaporation followed by subsequent annealing processes. Interfacial reactions in the Al/Pt/GaAs system proceed in two stages. Upon low temperature annealing Pt and GaAs react to form PtGa and PtAs2. Further high temperature annealing causes PtGa, PtAs2 and Al to react together producing the desired PtAl on GaAs. We observed solid-phase epitaxial regrowth of GaAs during the second stage of reaction. The PtAl/GaAs interface is determined to be thermally stable during an 800°C/30 min. anneal, while remaining morphologically uniform on GaAs.
A Two-Step Process for the Formation of Au-Ge Ohmic Contacts to n-GaAs
Authors: Dornath-Mohr M. A. , Cole M. W. , Lee H. S. , Wrenn C. S. , Eckart D. W. , Fox D. C. , Yerke L. , Chang W. H. , Lareau R. T. , Jones K. A. , Cosandy F. 
Published: March 2011

ABSTRACTThe formation of low temperature Au-Ge contacts to n-GaAs is a two-step process. In the first step, the metals segregate into Au and Ge rich regions and the intermixing of the Au and Ge with the Ga and As causes a reduction in the barrier height. The second step occurs after extended annealing, during which time Au and Ge continue to diffuse into the substrate. An orthorhombic Au-Ga phase is formed and it is likely that other Au-Ga or Ge-As phases are formed. The length of the extended anneal is dependent upon the atomic percent of Ge in the film, with the 10 at. % Ge taking 6 hr., the 27 at. % Ge taking 3 hr. and the 50 at. % Ge taking 9 hr. to become ohmic. The 75 at. % Ge sample doesn’t show ohmic behavior even after 33 hr. of annealing. The metal-semiconductor interface configuration appears abrupt, showing no protrusions into the GaAs substrate.
Au Ohmic Contacts to P-Type Hg1-xCdxte Utilizing Thin Interfacial Layers
Authors: Krishnamurthy V. , Simmons A. , Helms C. R. 
Published: March 2011

ABSTRACTOhmic behavior is observed in electroless Au contacts to p -type Hg1−xCdxTe. Our investigation of the interfacial chemistry of such contacts suggest that this ohmic behavior may be due to the presence of a Te,O, and CI layer. To verify this correlation with interfacial chemistry, thin plasma oxide layers were used in evaporated Au contacts. The annealed plasma oxidized contacts exhibited low contact resistances. This behavior was attributed to a low interface state density at the interfacial layer/Hg1−xCdxTe interface. In comparison, as-deposited and annealed Au contacts without a thin interfacial layer were rectifying with a large barrier height.
Susceptor and Proximity Rapid Thermal Annealing of InP
Authors: Katz A. , Pearton S. J. , Geva M. 
Published: March 2011

ABSTRACTAn intensive comparison between the efficiency of InP rapid thermal annealing within two types of SiC-coated graphite susceptors and by using the more conventional proximity approach, in providing degradation-free substrate surface morphology, was carried out. The superiority of annealing within a susccptor was clearly demonstrated through the evaluation of AuGe contact performance to carbon-implanted InP substrates, which were annealed to activate the implants prior to the metallization. The susceptor annealing provided better protection against edge degradation, slip formation and better surface morphology, due to the elimination of P outdiffusion and pit formation. The two SiC-coated susceptors that were evaluated differ from each other in their geometry. The first type must be charged with the group V species prior to any annealing cycle. Under the optimum charging conditions, effective surface protection was provided only to one anneal (750°C, 10s) of InP before charging was necessary. The second contained reservoirs for provision of the group V element partial pressure, enabled high temperature annealing at the InP without the need for continual recharging of the susceptor. Thus, one has the ability to subsequentially anneal a lot of InP wafers at high temperatures without inducing any surface deterioration.
In-Based Ohmic Contacts to the Base Layer of GaAs-AlGaAs Heterojunction Bipolar Transistors
Authors: Ren F. , Pearton S. J. , Hobson W. S. , Fullowan T. R. , Emerson A. B. , Yanof A. W. , Schleich D. M. 
Published: March 2011

ABSTRACTThe use of AuBe-In/Ag/Au p-ohmic contacts for the base layer of GaAs-AIGaAs heterojunction bipolar transistors (HBTs) is described. Annealing at 420°C for 20 sec produces a contact resistivity of 0.095 Ω mm and a specific contact resistance of l.5 × 10-7 Ω cm2, and the surface morphology of the contact is excellent. The role of the silver is as a diffusion barrier to prevent Au spiking into the base layer which could degrade the HBT performance. The presence of the In layer is highly desirable in order to reduce the contact resistance, probably by forming an InGaAs phase at the metal-GaAs interface. Beryllium acts as the p-type dopant, and the top Au layer is used to lower the contact sheet resistance. Current transport through the structure is dominated by tunneling through the barrier due to field emission in the highly doped base layer at p-type doping levels above ∼1019 cm−3
Interaction of Copper Film with Silicides
Authors: Shy Yow-Tzong , Murarka Shyam P. , Shepard Carlton L. , Lanford William A. 
Published: March 2011

ABSTRACTBilayers of Cu with TiSi2 and TaSi2 were tested by furnace annealing at temperatures from 200 to 500°C. Rutherford Back Scattering (RBS) technique was used to investigate the interaction between various films and determine the stability of Cu on silicide structures. The sheet resistance was also monitored. The results show that Cu on TiSi2 and TaSi2 structures are extremely stable structures at annealing temperatures in the range of room temperature to 500 °C. In such structures, therefore, there will not be a need of any diffusion barrier between Cu and the silicide films.
Analysis of Materials from a Late 15th-Early 16th Century Polychromed Wood Sculpture
Authors: Stodulski L. P. , Dorge V. J. 
Published: March 2011

AbstractDuring conservation, The Detroit Institute of Arts' late Gothic carved wooden sculpture, Madonna and Child, was found to have extensive, though fragmentary, remains of the original polychromy and at least four subsequent “restoration” overpaints. The materials present in the original and overpaintings were probed by polarizing microscopic and X-ray diffraction analyses of individual paint specimens, and scanning electron microscopic/energydispersive X-ray analyses of cross sections prepared using an ultramicrotome. Several sections were also studied using ultraviolet fluorescence microscopic staining techniques to determine the nature of the media used.The pigments identified include azurite, lead white, calcite, vermilion, red lead, hematite, red lakes and glazes, smalt and Prussian blue. Gold and silver metal leafs were also detected. The deteriorated remains of the late Gothic pressed brocade technique, and the use of “bronze” paint to approximate genuine gold leaf on a later addition to the sculpture, are also discussed.
Surfactants and Adherent Silicon Resins - New Protective Agents for Natural Stone
Authors: Snethlage Rolf , Wendler Eberhard 
Published: March 2011

AbstractThe present paper reports investigations on the application of surfactants in the stone conservation. It is found that alkyl ammonium chlorides reduce the hygric dilatation of clay-rich sandstones to half of the original value. Polysiloxane films can be tightly bound to clay mineral basal planes using aminoalkyl silane as primer. The water uptake as well as the hygric swelling are markedly reduced. Well defined mixtures of ethanolic alkyl silane and aqueous aminoalkyl silane solutions form stable microemulsions. They can be used as commercial conservative products which are compatable with the environment.
Modification of the Physical Properties of Natural and Artificial Adobe by Chemical Consolidation
Authors: Coffman Richard L. 
Published: March 2011

AbstractThe use of commercially available chemical consolidants (hexamethylene diisocyanate (HDI) - derived polymers and silane esters) has been shown to increase the compressive strength of adobe and other natural building materials. Laboratory and field testing of chemically-treated adobe and sand-clay mixtures have also revealed an enhanced resistance to disintegration by water.In HDI-treated materials this resistance to disintegration is attained without a significant loss of porosity. Because porosity is not lost and the adobe can still transmit water, the uptake of water by capillary rise is less destructive than for an adobe whose surface is sealed against moisture penetration.
Protective Coatings for Medieval Stained Glasses
Authors: Schmidt H. , Fuchs D. 
Published: March 2011

AbstractThe corrosion protective effect of the surface modification of corrosion sensitive glass surfaces and of ORMOCER (= organically modified ceramic) coatings is investigated. The surface modification provides a modest protection, perhaps useful for additional protection in combination with external glazing. The advantage is the “invisability” of the modification due to the thickness of several molecular layers. An effective protection can be obtained by a diffusion barrier pigmented ORMOCER coatings. First outdoor results on medieval glasses are very hopeful, but long period experience is necessary for wider application.
Venice: Stone Material Behaviour in Connection with the Environment
Authors: Biscontin G. , Fassina V. , Miaravelaki P. , Zendri E. 
Published: March 2011

AbstractThe present study is directed to summarize several studies carried out in the recent past on stone decay processes taking place in the lagoon environment of Venice. The behaviour of the main types of stones used in Venetian buildings has been considered.Istrian stone, Verona red stone and Carrara marble were studied.The knowledge of the porosity and of the pore size distribution can contribute to clarify the physical transformation of decayed materials.The research determined the morphology of stone decay processes for the different types of stone.As far as the morphology of deterioration is concerned, there are two main types of decay which depend on the intrinsic properties of the stone: chemical-mineralogical composition and texture-structure.
Recognizing the Limits of Archaeological Applications of Non-Destructive Energy-Dispersive X-Ray Fluorescence Analysis of Obsidians
Authors: Bouey Paul D. 
Published: March 2011

AbstractApplication of a non-destructive energy-dispersive XRF technique, involving use of analytc/Compton net peak ratios, has greatly increased the analytical potential for the study of obsidians in archaeological assemblages. Contrary to reported conclusions for obsidians from the Coso Volcanic Field of southeastern California, however, the method lacks the precision associated with powdered-specimen, thin film, and other more rigorous techniques. Tests have shown that changing the orientation and/or placement of an archaeological artifact in a sample slot will produce widely divergent determinations of ppm concentrations for most specimens. These results indicate that discriminating between some chemical subsources at Coso cannot be accomplished reliably.
Nondestructive Evaluation of the Mineralogy of Rock Temper in Ceramics Using X-Radiography
Authors: Carr Christopher , Komorowski Jean-Christophe 
Published: March 2011

AbstractIndustrial and medical x-radiography can be used in a new manner analogous to back-scattered electron microscopy to identify the approximate mineralogy of rock temper particles in ceramics, but without their destruction by thin-sectioning and at very low cost. Mineralogical traits similar to those applied in petrography to identify mineralogy are visible in a magnified radiograph. They include particle radiographic grey level contrast, which varies with specific density and mineralogy; morphology; cleavage; and internal texture. Blind tests that evaluate the specificity and accuracy of the method are presented.
The Use of Potsherds for Interpreting Alluvial Deposits: A Case Study in the Adige River Basin (Italy)
Authors: Balista C. , Levi S.T. , Vanzetti A. , Vidale M. 
Published: March 2011

AbstractThe paper discusses the use of a small assemblage of potsherds as evidence of fluvial erosion and indicators of microstratigraphical and geomorphological processes. The potsherds, sandwiched between 2 alluvial deposits, provide dating criteria for the two stratigraphic units, very important for understanding the geomorphology of the whole region. By integrating evidence of negative interfaces on potsherds by fluvial erosion and sedimentological evidence, it is possible to reconstruct the local stratigraphic formation processes. Furthermore, the paper discusses some theoretical implications of this case study for stratigraphic analysis. Negative interfaces produced by erosion on sediments and ceramics are considered in the same analytical framework; in both cases, they represent cumulative units preserving the record of complex stratigraphic processes. Far from being simple limits marking gaps in sedimentary deposition, erosive interfaces are very particular types of strata to be recorded and studied with geoarchaeological methods and with the same detail of traditional sedimentary units.
Patination of Ceramic Objects, Modern and Prehistoric: A Case from West Mexico
Authors: Aronson Meredith , Kingery W. David 
Published: March 2011

AbstractIn many cases objects lacking specific provenience are deemed inappropriate for archaeological or art historical studies. The application of analytical techniques such as thermoluminescence or carbon-14 dating have been used in conjunction with stylistic information to strengthen arguments for provenience. In the case of late-Formative figurines from West Mexico, careful study of the dark patina using morphological and chemical criteria provides a means of assessing provenience of the figurine. Comparison of modern patinas to provenienced patinas has been carried out at several levels -- visual/stylistic, morphological and chemical.
Role of Materials Analysis in the Reconstruction of Early Metal Extraction Technology: Zinc and Silver-Lead Smelting at Zawar, Rajasthan
Authors: Freestone I C , Middleton A P , Craddock P T , Gurjar L K , Hook D R 
Published: March 2011

AbstractMicroscopy and elemental analysis of ore, slag, ceramic and ash from a major metallurgical site have allowed insights into the ancient processes. Constraints have been placed on raw materials and smelting conditions, and aspects of technological change and development have been recognised.
Fifth Millennium BC Evidence for Metallurgical Processing of Copper and Copper Alloys in South-East Europe.
Authors: Glumac Petar D. , Todd Judith A. 
Published: March 2011

AbstractArchaeological materials recovered from excavations of settlements and cemeteries of prehistoric cultures in the Middle Danube basin offer new evidence for the production of metals by the beginning of the Eneolithic (late neolithic) period. The identification of malachite, azurite and galena indicates that these minerals were extracted from the upland ore-bearing zones and transported to the lowland, alluvial river valleys for processing and smelting at settlement sites. For the first time metallurgical slags, found in association with malachite ores, crucibles, and copper/bronze artifacts, suggest that copper was smelted as early as the fifth millennium BC. Detailed analyses of these slags have identified a unique find of a tinbearing copper slag, raising the question of bronze production during the fifth millennium BC.
High-Resolution Computed Tomography and Digital Radiography of Archaeological and Art-Historical Objects
Authors: SÉGuin Fredrick H. 
Published: March 2011

AbstractRecent advances in x-ray imaging and image processing are providing new options for the nondestructive physical evaluation of archaeological artifacts and works of art. Traditional film-based methods have played an important role in this field for many decades1, but digital modes developed for medical and industrial applications have been gaining ground2 and can be expected to become more important as they become more accessible and less expensive. Modes such as digital radiography (DR) and computed tomography (CT) have many advantages in terms of information content, quantitative analysis options, and image display options (including some that make image publication easier). CT, in particular, provides structural information which cannot be obtained through any other nondestructive means. From a technical point of view, the only real drawback to digital methods has been spatial resolution that hasn't compared favorably with the best available from film. That situation is changing3.The objective here is to discuss a few of the important characteristics peculiar to digital images, to show examples of how high-resolution digital images can provide important structural information, and to illustrate useful types of image processing. The use of experimental CT and DR systems, with spatial resolution as fine as 50 microns, is illustrated in studies of three objects: an ancient terracotta sculpture, a Japanese assembledwoodblock sculpture (ca. 17th century), and an oil painting on canvas (ca. 18th century).
Why is the Japanese Sword Curved ?
Authors: Weins William N. , Bleed Peter 
Published: March 2011

AbstractThe history and methodology of Japanese swordmaking are reviewed with particular reference to materials and processes. In order to gain a better understanding of the structure/property relationships in Japanese swords, a 16th century katana was analyzed metallographically and by attaching strain gages and cutting to relieve the residual stresses in the blade. The results indicate that the curve in the blade can be attributed to the volumetric expansion of the untempered martensite on the cutting edge, which also causes the edge to be in a state of residual compression. The residual compressive stresses are one of the key elements of the Japanese sword which give it superior toughness and cutting ability.