bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical Contact and Adhesion Modification Produced by High Energy Heavy Ion Bombardment of Au Films on GaAs
Authors: Livi R. P. , Paine S. , Wie C. R. , Mendenhall M. H. , Tang J. Y. , Vreeland T. , Tombrello T. A.
Published: March 2011

Thin gold films over GaAs wafers with different dopants (Cr, Si, Te, and Zn) were used to study the role of he substrate electronic properties in the electrical contact and adhesion modification induced by MeV/nucleon heavy ion bombardment. The enhanced adhesion was studied using a scratch test; the results show very different modifications of adhesion depending on the bulk electronic properties of the substrate. The sample with a Cr compensation doped substrate showed enhancement in adhesion for beam doses as low as 1012 ions/cm2, but Si and Te doped (n–type) substrates showed a sudden enhancement in adhesion for doses around 1014 ions/cm2. Samples with Si and Te doped substrates were used to sudy the bombarding ion dE/dx dependence of the induced adhesion for 19F and 35C1 ions with electronic stopping power ranging from 161 eV/Å to 506 eV/Å. In this range the dose threshold fgfjhe ops! of induced adhesion has a power law dependence, D = D0(dE/dx)− (1.90 ± 1.0)
Improved Uniformity of Reacted GaAs Contacts by Interface Mixing
Authors: Palmrøm C. J. , Kavanagh K. L. , Hollis M. J. , Mukherjee S. D. , Mayer J. W.
Published: March 2011

Ion beam mixing is used to produce more uniform Au.Au-Ge and Au-Ge-Ni reacted contacts to GaAs.
Reaction of Amorphous Minb Films with Crystalline Metal Overlayers
Authors: Dobisz E. A. , Doyle B. L. , Perepezko J. H. , Wiley J. D. , Peercy P. S.
Published: March 2011

In many cases the stability of amorphous films is influenced by interaction with metallic crystalline overlayers. Such interactions between Au, Ni, Nb and Ta overlayers and a-(Ni-Nb) films are reported. During interdiffusion Au overlayers reacted with a-(Ni-Nb) to form two different adjacent crystalline layers. In order to study the influence of relaxation of the amorphous film on overlayer reaction several a-(Ni-Nb) samples were pre-annealed prior to Au deposition. High depth resolution Rutherford Backscattering Spectrometry (RBS) demonstrates that preannealing lowers the diffusion poefficient of Au in a-(Ni-Nb) at 4500C from 7.5×10−22 m2/s to 8.7×10−23 m22/s. During interdiffusion Ta was discovered to be substantially more inert than Au. For example, negligible interdiffusion between Ta and a-(Ni-Nb) at 505°C after 25 hours implies a diffusivity of less than 5×10−24 m2/s. These observations allow assessment of some of the requirements for increasing the stability of crystalline-amorphous metal film layered structures.
Structure and Coherence of Metallic Superlattices
Authors: McWhan D. B. , Hill Murray
Published: March 2011

Most of the papers in this symposium have dealt with superlattices formed from semiconductors with the diamond or zinc blende structure or derivative structures such as fluorite in which one sublattice has the diamond structure. Such superlattices are often called compositionally modulated alloys (CMA) because the two components have the same or related structures and because the two components have some mutual solubility. In these cases, depending on the differences in the lattice parameters, the resulting CMA will be almost a perfect single crystal, and the sharpness of the interfaces between the two alternating components will depend on the amount of interdiffusion during growth.
Superconducting Properties of Amorphous Multilayer Metal-Semiconductor Composites
Authors: Kadin A. M. , Burkhardt R. W. , Chen J. T. , Keem J. E. , Ovshinsky S. R.
Published: March 2011

Following the earlier multilayer work of Ovshinsky and colleagues, we have fabricated thin-film samples consisting of alternating periodic layers of a transition metal (Nb, Mo, W) and a semiconducting element (Si, Ge, C) by sequential sputtering from two targets onto room-temperature substrates. The regular repeat spacing has been varied from 10 Å to more than 100 Å, with as many as several hundred layer pairs. Crystalline epitaxy was not required or even desired; many samples were largely amorphous as determined from x-ray scattering. Electrical transport measurements of superconducting properties have been carried out parallel to the layers. Samples exhibited highly anisotropic superconducting critical magnetic fields, with some values in excess of 200kG parallel to the layers. Evidence suggesting an asymmetric interface profile will be presented.
Structural Properties of Single Crystal Rare-Earth Thin Films Y and Gd Grown by Molecular Beam Epitaxy
Authors: Kwo J. , McWhan D. B. , Hong M. , Gyorgy E. M. , Feldman L. C. , Cunningham J. E.
Published: March 2011

By means of metal MBE technique with in-situ RHEED characterization, high-quality single crystal rare earth metal films of yttrium and gadolinium were grown as a necessary requirement for studying Gd/Y superlattices. The key step of this successful growth is the employment of the single-crystal Nb film as a buffer layer to eliminate the interaction of rare earth metals with most substrates. Structural analyses by X-ray diffraction and ion channeling show that these crystals exhibit not only complete texture of [00.1], but also narrow rocking curves both perpendicular (00.2) and parallel (10.0) to the film.
Influence of Modulation Wavelength Induced Order on the Physical Properties of Nb/Rare Earth Superlattices
Authors: Greene L. H. , Feldmann W. L. , Rowell J. M. , Batlogg B. , Hull R. , McWhan D. B.
Published: March 2011

We report the observation of a higher degree of preferred crystalline orientation in Nb/rare earth superlattices for modulation wavelengths in the range of 200 Å to 500 Å than that exhibited by single component films. All films and multilayers are sputter deposited onto room temperature sapphire substrates. Electronic transport measurements also show that the residual resistance ratio is higher and the room temperature resistivity is lower than for multilayers of either greater or lower periodicities. Transmission electron micrographs (TEM) showing excellent layering, grain size comparable to the layer thickness, and evidence of some degree of epitaxy are presented.
Mechanical Properties of Composition Modulated Copper-Nickel-Iron Thin Films
Authors: Jankowski A. F. , Tsakalakos T.
Published: March 2011

The enhanced elastic modulus effect was found in composition modulated Cu/NiFe foils. Young's modulus was measured via tensile testing on thin foils containing short-wavelength composition modulations of 1.4–10. nm. The foils, of 53% Cu -40% Ni -7% Fe composition, were produced by vapor deposition using a three-source evaporator. As compared with homogeneous foils of the same average composition, the modulated foils exhibited an appreciable increase (up to 300%) in modulus for two distinct ranges of compositon wavelength: 2.1–2.7 nm and 3.6–4.1 nm. Results of x-ray diffraction and Mossbauer spectroscopy studies suggest the concept of interfacial coherency, accommodating the lattice misfit between the composition layers, is the underlying structural feature responsible for the enhanced modulus effect.
Solid-Phase Ohmic Contacts to GaAs with TiN Diffusion Barriers
Authors: Kattelus H. P. , Tandon J. L. , Hamdi A. H. , Nicolet M-A.
Published: March 2011

We report on contacts to p-type GaAs formed by a GaAs/Pt/TiN/Ag system. Ohmic behavior in this system is believed to be accomplished by the solidstate reaction of Pt with GaAs. This reaction is confined by the TiN film which is thermally stable. In addition, the TiN film acts as an excellent diffusion barrier in preventing the intermixing of the top Ag layer with GaAs or Pt. Contacts formed with such controlled reaction have important implications for the stability of shallow p-n junction devices.
Self Aligned Nitridation of TiSi2: A TiN/TiSi2Contact Structure
Authors: Rosser Paul J. , Tomkins Gary J.
Published: March 2011

Titanium nitride is an ideal barrier to silicon migration into aluminium metallisations in MOS devices. Various means by which a TiN,TiSi2 contact structure can be achieved to give low resistivity interconnects and stable contacts are outlined. It is shown that TiN/ TiSi2 contact structures self aligned to contact holes cut down to the TiSi2 can be simply achieved. Results showing the stability of the nitride film against silicon diffusion are presented.
Titanium Silicide Films Deposited by Low Pressure Chemical Vapor Deposition
Authors: Tedrow Prabha K. , Ilderem Vida , Reif R.
Published: March 2011

Smooth titanium silicide films have been deposited using a Low Pressure Chemical Vapor Deposition (LPCVD) process. A system has been designed and built for the LPCVD of titanium silicide. It is a cold wall reactor with the wafer being heated externally by infrared lamps. Sequential deposition of polycrystalline silicon (polysilicon) and titanium silicide films, and in-situ annealing of these films, if required, can be performed in this system. A turbomolecular pump is used to provide a contaminant free environment with a base pressure of <10−7 torr. SiH4 and TiCl4 are used as silicon and titanium sources, respectively.

Tithnium silicide films with resistivities ranging from 22 to 39 μΩ-cm have been obtained. At low deposition rates, these films have surface roughnesses ranging from 50 to 250 Å. From X-ray diffractometry, it was determined that the as-deposited titanium silicide films were polycrystalline, and TiSi2 was the predominant phase. Si/Ti ratios of 1.8 to 2.3 were obtained frog Rutherford Backscattering Spectroscopy (RBS). Auger analyses did not show any impurities such as oxygen, carbon or chlorine in these films.
Pre-Annealing of TiN Barriers in Al Metallization of Silicon
Authors: Sinke W. , Stout P. K. , Saris F. W.
Published: March 2011

We have studied the influence of a high-temperature pre-anneal on the barrier performance of TiN in Al metallization of Si. The results show that barrier failure is shifted towards a higher temperature by 20°C-40°C when the barrier is pre-annealed at 600°C-800°C. In addition, we studied the failure mechanism and found that the barrier breaks down by compound formation.
Epitaxial Phases Formation Due to Interaction Between Ni Thin Films and GaAs
Authors: Lahav A. , Eizenberg M. , Komem Y.
Published: March 2011

Solid state reactions between Ni thin films and (100) GaAs were studied by transmission electron microscopy, X-ray diffraction, Auger electron spectroscopy and Rutherford backscattering. The hexagonal ternary phase Ni2GaAs is formed at the temperature range of 150 to 300°C with the following epitaxial relations to the substrate: (1011)//(001) and [1011]//[100]. The gradual decrease with temperature of the (1011)interplanar spacing of this phase may be related to strain relaxation associated with microtwins formation. At the temperature range of 350 to 550°C precipitation of NiAs in Ni2GaAs matrix and an increase of the twin size are observed. In this range the (1011) interplanar spacing of the ternary phase increases with temperature, possibly due to stoichiometric changes resulting from NiAs precipitation. At 600°C the ternary phase decomposes into NiGa and NiAs with average grain size of about 1 micron in lateral dimension. The cubic phase, NiGa, has simple epitaxial relations with GaAs: (001)//(001) and [010]//[010].Ni atoms are the dominant diffusing species during the ternary phase growth process as was observed in a marker experiment utilizing a very thin Ta Layer interposed between the Ni film and the substrate.
Dynamics of Laves Phase Intersections in a Concentration Gradient
Authors: Allen C. W.
Published: March 2011

In the approximate interval 850–1150C, the Laves phase TiCr2 exhibits several composition dependent structures, ranging from two layer hexagonal (2H), denoted C14, to face-centered cubic, denoted C15, for Ti-deficient and Ti-excess material, respectively. Intermediate stacking variants such a dihexagonal (4H), denoted C36, may also exist. The Laves phase band in a Ti-Cr microdiffusion couple is examined in cross-section TEM at ambient temperature, after a 1000 C anneal. The band consists of very faulty hexagonal material, at least in part reflecting rapid shear transformation on cooling; in addition the cubic phase is present, in some instances within the same grain as the hexagonal phase. The cubic/hexagonal interfaces are approximately parallel rather than perpendicular to the bulk diffusion direction. Due to a difference in Ti and Cr fluxes, there is a gradual transformation of cubic to hexagonal by a shear mechanism. A model for the mobility of the hexagonal/cubic interface in a concentration gradient is proposed.
Influence of Phosphorous on the Kinetics of Ordering in Ni2Cr
Authors: Lehman Lawrence P. , Kosel T. H.
Published: March 2011

The isothermal ordering kinetics of stoichiometric Ni2Cr was investigated in specimens aged at 500°C and containing 3 different phosphorous impurity concentrations; 0.004, 0.032, and 0.142 atomic percent P. In every case, higher P specimens were found to transform more rapidly than lower P content specimens, with as much as an order of magnitude difference in transformation times. Low and medium P specimens transformed via a continuous ordering process. In contrast, the highest P specimens transformed by an unusual process in which colonies of ordered domains were formed which consumed grains through the advance of an order-disorder interface. Colonies tens of microns in size were typically observed while individual ordered domains were only a few tens of nm in size.
Ordered Alloys for High Temperature Applications
Authors: Stoloff Norman S.
Published: March 2011

This paper will provide an overview of the current status of the development of ordered alloys for high temperature structural applications. The physical and mechanical properties of ordered alloys will be reviewed with particular emphasis on aluminides and (FeNiCo)3V alloys. Alloy theory, slip systems, yielding, strain hardening, fatigue, wear resistance and processing are among the subjects to be covered. Current research programs in the U.S. and abroad will be outlined, and the kinds of scientific and application-oriented research needed in the future will be discussed.
Theories of Alloy Ordering - Overview and Forecast
Authors: Clapp Philip C.
Published: March 2011

The task of any alloy ordering theory simply put is to predict from a small amount of experimental data the ordering phase transitions, their temperature, composition and crystal structure in some selected alloy system. Ideally, the experimental information needed would be not more than the atomic numbers of the alloy components involved. This paper attempts to assess the progress that has been made towards that objective, the various techniques that have been used to provide solutions and the probable avenues of most rapid progress in the next ten years. The major areas that will be reviewed are Ising model approaches, many body interaction approaches, computer simulation techniques, and first principle calculations. It will be argued that we are on the verge of some quite exciting breakthroughs in the field of alloy phase prediction.
Property Comparison of Melt-Spun Ribbons and Consolidated Powders of Ni3A1-B
Authors: Chang K-M , Taub A. I. , Huang S. C.
Published: March 2011

Ductile intermetallic Ni3 Al-B alloys have been processed through three rapid solidification techniques: melt spinning, gas atomization, and plasma deposition. Different thermal treatment was required for each rapidly solidified product to form samples for mechanical evaluation. Melt-spun ribbons were tested in ribbon form in the as-cast or annealed conditions, while atomized powders were tested after consolidation by hot isostatic pressing (HIP) or low pressure plasma deposition. Alloy strength, as well as tensile ductility, was found to depend strongly on processing technique, thermal treatment, sample geometry, and most importantly, alloy chemistry. Microstructural and fractographic observations indicate that grain boundary brittleness caused by material processing history plays the major role in determining the alloy's mechanical behavior.
Rapidly Solidified NiAl and FeAl
Authors: Gaydosh Darrell J. , Crimp Martin A.
Published: March 2011

Melt spinning was used to produce rapidly solidified ribbons of the B2 intermetallics NiAl and FeAl. Both Fe-40Al and Fe-45A1 possessed some bend ductility in the as spun condition. The bend ductility of Fe-40Al, Fe-45Al, and equiatomic NiAl increased with subsequent heat treatment. Heat treatment at approximately 0.85 Tm resulted in significant grain growth in equiatomic FeAl and in all of the NiAl compositions. Low bend ductility in both FeAl and NiAl generally coincided with intergranular failure, while increased bend ductility was characterized by increasing amounts of transgranular cleavage fracture.
High Temperature Oxidation of β-NiAl
Authors: Doychak Joseph K. , Mitchell T. E. , Smialek J. L.
Published: March 2011

The oxidation of single crystal β-NiAl has been studied primarily using electron microscopy. Oriented metastable Al2O3phases form during transient oxidation at 800°C. Specific orientation relationships exist on all metal orientations studied and are a result of the small mismatch along aligned close-packed directions in the cation sublattices of the metal and oxide. Transformation of the metastable Al2O3, phases at 1100°C results in an oxide morphology described as the “lacey” structure of α-Al2O3scales. This structure results from impingement of oriented patchei α a-Al2O3as the transformation initiates and moves radially parallel to the sugfhce. Scale growth occurs by diffusion along high angle grain boundaries. A drastic reduction in oxidation rate accompanies the change in oxide morphology.
Ordering Behavior and Corrosion Properties of Ni-Mo and Ni-Mo-Cr Alloys
Authors: Tawancy H. M. , Asphahani A. I.
Published: March 2011

Ni-Mo alloys containing 26–28 wt. pct. Mo are known for their excellent corrosion properties in reducing environments. When exposed to temperatures in the range 600°C to 800°C, however, these alloys undergo a longrrange ordering reaction from disordered fcc lattice to ordered Dla superlattice. This ordering phenomenon has been found to have detrimental effects on corrosion properties. Also, alloys based on the Ni-16Mo-16Cr system undergo a long range ordering reaction from disordered fcc lattice to ordered Pt2Mo-type superlattice in the temperature range of 400° to 600°C. However, in contrast to the case of Ni-Mo alloys, ordering in the Ni-Mo-Cr alloys has some beneficial effects on the aqueous corrosion properties. This difference in behavior between the Ni-Mo alloys and the Ni-Mo-Cr alloys is discussed interms of the ordering characteristics determined from transmission electron microscopy and diffraction, X-ray microanalysis in the scanning transmission electron microscope and Auger electron spectroscopy.
Magnetic Studies of Ni3Al(Fe) Compounds
Authors: Sekula S. T. , Kerchner H. R. , Thompson J. R. , Leventouri Th.
Published: March 2011

Several samples of the ordered intermetallic compound with the Ll2 structure and chemical composition NiO.75-xAl0.25-xFe2x (doped with 0.2 at. % B) have been studied over an Fe compositional range 0 ≤ 2x ≤ 0.20. Stoichiometric Ni3Al is known to be a strongly exchange-enhanced-material, forming a giant moment system when Fe impurities are introduced in trace amounts. For the greater Fe concentrations employed in this work, more conventional ferromagnetic systems are obtained. Well below the ferromagnetic Curie temperature Tc the samples exhibit a spontaneous moment in small magnetic fields and at higher fields the isothermal magnetization data show a clear tendency toward saturation. Magnetic investigations using vibrating-sample techniques permitted measurements over the temperature interval from 4.2 K to 800 K in fields up to 5.0 T. The Curie temperature was found to increase from ∼50 K for the Fe-free sample in the series to 410 K for the limiting concentration of 12 at. % Fe in the Ll2 structure. Samples with higher Fe content up to 20 at. % contain a second, disordered fcc phase with Tc ≃ 715 K. Peaks in the temperature dependence of the lattice parameter observed in x-ray studies yield Tc values in reasonable agreement with the magnetic measurements.
Influence of Microstructure on the Corrosion Behavior of a Ni-Si Alloy
Authors: Kumar P.
Published: March 2011

Nickel-based alloys with over 7 percent silicon have excellent corrosion resistance to sulfuric acid, oleum and sulfate-ion-containing environments. This alloy is characterized by the presence of intermetallic Ni3Si (beta) and Ni5Si2 (gamma) phases in Ni-Si solid solution (alpha) matrix. The corrosion resistance is provided by the coarse intermetallic phases. Size of intermetallic phases is dependent on the processing condition and the heat treatment. The corrosion resistance can be changed by heat treatment.

Results of corrosion tests are explained in terms of microstructural features.
Modulated Microstructures in β-Phase Alloys
Authors: Wayman C. M.
Published: March 2011

Many ordered β-phase alloys of the B2 or D03 types exhibit unusual diffraction patterns and images when examined in the transmission electron microscope. These effects include “extra” diffraction spots, diffuse scattering, satellites, “tweed microstructures, spinodal decomposition and the formation of incommensurate phases. Examples of these phenomena will be presented and discussed. Although most of the β-alloys also undergo a martensitic transformation at some lower temperature it will be argued that the above effects are not “premartensitic” or precursory in nature. However many of them can be related to certain properties of the β-phase such as elastic anisotropy, a soft phonon mode and electronically driven instabilities.
Melting Phenomena and Interfacial Instability Associated with Laser Irradiation
Authors: Narayan J.
Published: March 2011

The work on annealing of displacement damage, dissolution of boron precipitates, dopant redistribution and formation of constitutional supercooling cells using pulsed ruby and dye laser irradiation is reviewed in order to provide convincing evidence for melting as a primary mechanism of laser annealing. The nature of the liquid-solid interface and the interfacial instability during laser-induced rapid crystal growth are considered in detail. Solute concentrations after laser annealing can far exceed retrograde solubility limits, but there is a critical concentration above which a planar liquid-solid interface becomes unstable and breaks into cellular structures. The solute concentrations and cell sizes associated with this instability have been studied as a function of crystal-growth velocity and these results compared with calculations of the perturbation theory. Good agreement between the experimental results and the theory was obtained when the dependence of the distribution coefficient upon crystal growth velocity was taken into account in the calculations.
Fundamentals of Energy Transfer During Picosecond Irradiation of Silicon
Authors: Bloembergen N. , Kurz H. , Liu J.M. , Yen R.
Published: March 2011

The fundamentals of energy transfer in semiconductors during and following pulsed laser excitation are reviewed within the frame of results obtained in picosecond laser experiments. This paper discusses the theoretical processes as well as the experimental evidence, which sets limits of electron and lattice temperature of irradiated silicon. Simple thermal melting is the most probable explanation for the laser induced phase transitions observed.
Picosecond Laser Pulse Induced Damage in Crystalline Silicon
Authors: Merkle K. L. , Uebbing R. H. , Baumgart H. , Phillipp F.
Published: March 2011

Picosecond laser pulse irradiation of single crystalline Si can produce severe damage, including amorphisation. Morphology changes are studied by means of optical and high-voltage-electron microscopy and are found to depend on energy fluence, surface orientation, and wavelength. The detailed analysis of the damage distributions and thresholds lead to the conclusion, that energy-confinement precedes the introduction of structural changes, which are formed by rapid quenching from the liquid state.
Laser and Ion Beam Mixing Cr and Ni + Cr Films on Cu.
Authors: Draper C. W. , Jacobson D. C. , Gibson J. M. , Poate J. M. , Vandenberg J. M. , Cullis A. G.
Published: March 2011

Thin films of Cr and Cr films capped with Ni–8V have been magnetron sputter deposited on both single crystal and polycrystalline Cu and Cu alloy substrates. Surface alloying has been accomplished with scanning second harmonic Q-switched Nd-YAG and single shot Q-switched Ruby lasers and with 1 MeV Xe ions. The films and surface alloys have been characterized with RBS and channeling, AES and sputter profiling, optical microscopy, SEM, TEM and glancing angle XRD. Surface alloys containing as much as 50 at. % Cr have been produced. Following laser melting it is possible to produce substitutional solid solutions of Cr in Cu far in excess of equilibrium values.
Studies of Laser-Alloyed Zr-Containing Surface Layers
Authors: Draper C. W. , Den Broeder F. J. A. , Jacobson D. C. , Kaufmann E. N. , Mcdonald M. L. , Vandenberg J. M.
Published: March 2011

Thin films of Cu on Zr and of Zr on Fe, Ni, Al, V, and Ti have been laser-pulse alloyed with the substrate metals using a raster-scanned Q-switched Nd:YAG laser. The high quench rates from the liquid state attendant to laser-pulse melting can promote the retention of a variety of metastable alloy phases. Structure and composition of the surface alloy layers of submicron thickness were studied with Rutherford backscattering (RBS)/channeling spectroscopy, optical and transmission electron microscopy and glancing angle x-ray diffraction (XRD). Composition profiles are compared with expected liquid-state diffusivities and structures are related to properties of bulk alloys. For example, in the well-known glass-forming system Cu-Zr, an amorphous phase was formed which crystallized upon annealing above Tc. In the Zr-Ti system, which shows complete solid solubility across the binary phase diagram in both the α and β phases, the hexagonal α-phase alloy is formed. Additional results on these and other systems are described below.
Phase Segregation During Laser Melting of Ni-Si and Co-Si Films
Authors: Bosch M.A. , Dayem A.H. , Harrison T.R. , Lemons R.A.
Published: March 2011

In this study Ni-Si and Co-Si films were deposited on fused quartz substrates by coevaporating the metal and silicon. The source separation and deposition rate were chosen to produce a composition range across the substrate. These films were then melted with a scanned cw argon laser beam. This results in a dramatic phase segregation that is readily observed in a light or scanning electron microscope. For the Ni-Si sample two phases separate into irregularly shaped regions up to ≈l10μm size. Electron microprobe measurements indicate that one phase is NiSi2 while the other is pure Si. With the Co-Si sample two phases segregate into narrow stripes that usually follow the temperature gradient produced by the scanned laser beam. The composition analysis indicates that these phases are CoSi and CoSi2. A possible cause for this morphology is discussed.
Beam Recrystallized Silicon-On-Insulator Devices
Authors: Lam H. W.
Published: March 2011

Beam-recrystallized silicon-on-insulator is an attractive material for VLSI integrated circuit and flat panel display applications. This paper describes the electrical characteristics that are unique to MOSFETs fabricated in this material. The back-interface between the silicon and the insulator significantly affects the leakage current by acting as a possible leakage path, depending on the charge at the back interface and the doping concentration in the silicon close to the back interface. In addition, enhanced arsenic diffusion along grain boundaries can cause short circuits between the source and the drain of an n-channel MOSFET. Evidence of such enhanced diffusion are presented as well as means to reduce the impact of the problem. It is shown that molecular hydrogen can be used to passivate the grain-boundaries in the recrystallized silicon material, thereby increasing the carrier mobility. A profile of the carrier mobility as a function of depth from the surface of the silicon is presented, showing that the carrier mobility is not reduced significantly, even close to or at the back interface.
The Gentle Electronic Nature of Pulsed Beam Annealing, or Does It Really Go Superfluid?
Authors: Van Vechten J. A.
Published: March 2011

Until recently two theories of what may be occurring during pulsed laser/electron/ion beam annealing of Si, Ge, GaAs, and other semiconductors enjoyed credence. One held that the material became hot and underwent normal thermal melting. The other held that the material annealed in the presence of a hot dense plasma of excited free carriers, electrons and holes. A closer examination of previous experiments, as well as new experiments, particularly those of Marquardt et al., which indicate an absence of free carrier absorption in the infrared, make both these theories untenable. They also make possible a more sophisticated understanding of what really is happening. The present status of this subject is reviewed. In particular the available evidence that the plasma excited by the pulsed radiation undergoes a boson condensation to a superfluid phase is described.
Grain Enlargment in Polysilicon on Insulating Substrates Induced by Q-Switched Nd:Yag Laser Irradiation
Authors: Falster R. J. , Eggermont G. E. J. , Gibbons J. F.
Published: March 2011

A systematic investigation of the formation of large grained rings in polysilicon by Q-switched laser irradiation has been performed. Parameters varied in this study were polysilicon thickness, substrate temperature and underlying oxide thickness. Increasing ring widths were obtained for increasing substrate temperature, polysilicon film thickness and underlying oxide thickness. The width of these rings was found to be independent of incident laser power above a certain threshold value. Surface morphology and the occurrence of cracking and ablation in these films as a function of these parameters was also investigated.
Uniform and Directed Crystallization of Deposited a­Si on Glass Substrates at Linear Velocities Of 1 to 20 Meters Per Second
Authors: Bensahel D. , Auvert G. , Nguyen V. T. , Rozgonyi G. A.
Published: March 2011

It has been found that careful control of the laser power and scan speed will convert deposited a­Si into continuous lines of uniformly crystallized silicon. Two solid phase “explosive” crystallization front velocities of 1000 cm/sec and 1400 cm/sec have been experimentally determined by matching the laser scan velocity with the runaway a–c phase boundary. If solid phase explosive crystallization is suppressed by pre-annealing, then a liquid assisted runaway crystallization velocity of 220 cm/sec is observed, as well as a continuous furnace-like crystallization process at 250 cm/sec.
Silicon Devices Fabricated by Using Laser Irradiation Process
Authors: Tamura M. , Natsuaki N. , Miyao M. , Ohkura M. , Murai F. , Takeda E. , Minagawa S. , Tokuyama T.
Published: March 2011

The advantages and disadvantages of both pulsed and cw scanned laser processing for Si devices are discussed. In particular, adaptions of laser processes for MOSFETs and bipolar structures are described from the viewpoint of active layer annealing. Moreover, MOSFETs fabricated in laser induced grown Si films on Si substrates having SiO2 patterns by bridging epitaxy, are discussed, as a function of sample structures, film formation conditions and laser irradiation conditions.
Photoluminescence of Pulsed Ruby Laser Annealed Crystalline and Ion Implanted GaAs
Authors: Lowndes Douglas H. , Feldman Bernard J.
Published: March 2011

In an effort to understand the origin of defects earlier found to be present in p–n junctions formed by pulsed laser annealing (PLA) of ion implanted (II) semiconducting GaAs, photoluminescence (PL) studies have been carried out. PL spectra have been obtained at 4K, 77K and 300K, for both n–and p–type GaAs, for laser energy densities 0 ≤ El ≤ 0.6 J/cm2. It is found that PLA of crystalline (c−) GaAs alters the PL spectrum and decreases the PL intensity, corresponding to an increase in density of non-radiative recombination centers with increasing El. The variation of PL intensity with El is found to be different for n– and p–type material. No PL is observed from high dose (1 or 5×1015 ions/cm2 ) Sior Zn-implanted GaAs, either before or after laser annealing. The results suggest that the ion implantation step is primarily responsible for formation of defects associated with the loss of radiative recombination, with pulsed annealing contributing only secondarily.
Multiply Scanned Electron Beam Annealing of Si Implanted GaAs
Authors: Bujatti M. , Cetronio A. , Nipoti R. , Olzi E.
Published: March 2011

Experimental results obtained by multiply-scanned electron beam annealing (MEBA) of Si implanted semi-insulating GaAs are presented and compared with results obtained by thermal annealing. A tentative model for Cr redistribution during MEBA treatment is presented which can explain the 100% activation without compensation threshold and the high drift mobility obtained for low Si doses, almost independent of the Cr content of the crystal.
Epitaxial Ge/GaAs Heterostructures by Scanned CW Laser Annealing of a-GE Layers on GaAS
Authors: Greene J.E. , Cadien K.C. , Lubben D. , Hawkins G.A. , Erikson G.R. , Clarke J.R.
Published: March 2011

Epitaxial regrowth of Ge/GaAs heterostructures by scanned laser annealing of amorphous Ge films on GaAs substrates has been studied as a function of laser power and scan rate. At least eight regimes representing different film regrowth characteristics were observed. Of these, two were of primary interest. At low powers (between~1.6 and 3.2 W for a beam diameter of~40 μm) and scan rates between 1 and 400 cm/sec, polycrystalline Ge with a (100) preferred orientation was formed by an “explosive” crystallization mechanism. At higher powers, and over a scan rate range of 25 to 400 cm/sec, single crystal metastable (GaAs)1−x Gexalloys were obtained by liquid phase regrowth. Typical film resistivities, ρ, were as follows: as-deposited ρ=180Ωcm; polycrystalline films, ρ=3 × 10−2 Ωcm; single crystal films,ρ=9×10−4Ωcm.
A Laser Triggered Self-Sustaining Metals-Compound Semiconductor Transition for AlSb
Authors: Andrew R. , Baufay L. , Pigeolet A. , Laude L.D.
Published: March 2011

The preparation of AlSb thin films by pulsed laser annealing of Al/Sb sandwiches is studied in order to resolve some past controversy about the temperature rise induced by the laser pulse. Using 1000 Ȧ thick two layer films supported by TEM grids, we investigate the energy threshold for complete transformation as a function of pulse duration from 15 nsec to 100 msec, and of ambient temperature from −100°C to 250°C.

We thence calculate the temperature effect directly induced by the laser to be about 930°C, or approximately the melting point of the metals, whereas inert gas furnace anneals of comparable films show transformation at this temperature occuring only in about 100 sec. We discuss the isoenergetic nature of the system for short laser pulses and the role of the heat of transformation, and thus conclude that the reaction is thermally triggered by the laser pulse but is to some extent self-sustaining via the heat of transformation locally distributed. This model is also shown to have equal validity for the systems CdTe, CdSe and AlAs.
Time Resolved Transmission and Reflectivity of Pulsed Ruby Laser Irradiated Silicon
Authors: Lowndes Douglas H. , Jellison G. E. , Wood R. F.
Published: March 2011

The time resolved optical transmission, T (atλ = 1152 nm), and reflectivity, R (at 633 nm and 1152 nm), have been measured for n-type single crystalline silicon (c-Si) during and immediately after pulsed ruby laser irradiation (λ = 693 nm, FWHM pulse duration 14 nsec), for a range of pulsed laser energy densities, El. The T is found to go to zero, and to remain at zero, for a period of time that increases with increasing El, in apparent disagreement with earlier measurements elsewhere that used semi-insulating Si and a different pulsed laser wavelength. Measured reflectivities during the high R phase agree within experimental error with reflectivities calculated from the optical constants of molten Si. Quantitative agreement is also found between both our T and R measurements and detailed time– and El-dependent results of thermal melting model calculations.
Transient Heating with Graphite Heaters for Semiconductor Processing
Authors: Fan John C. C. , Tsaur B-Y. , Geis M. W.
Published: March 2011

Transient heating with graphite heaters has been shown to be very useful in several important semiconductor processing applications. Using stationary and/or movable heaters, we have obtained excellent results in the annealing of ion-implantation damage in Si and GaAs, preparation of epitaxial Ge1−xSix on Si substrates, and recrystallization of Si films on insulators. The advantages of graphite heaters include their ready scalability in area to commercial wafer size and their low capital cost. These heaters are also easily machinable, and their temperature can be rapidly varied. When fully developed, this heating technique should provide an inexpensive and versatile method for commercial processing of many semiconductor materials.
Characterization of Ion-Implanted Si Rapidly Annealed with Incoherent Light
Authors: Benton J. L. , Celler G. K. , Jacobson D. C. , Kimerling L. C. , Lischner D. J. , Miller G. L. , Robinson Mc.D.
Published: March 2011

Irradiation of Si wafers for 5 to 10 sec with high intensity tungsten halogen lamps produces complete recovery of the displacement damage resulting from ion implantation. Data for two different thermal cycles are presented, with As and B implant doses ranging from 1013 to 1016 ions cm−2. Sheet resistance measurements combined with Rutherford backscattering indicate full electrical activation of dopants with very little diffusion. Carrier lifetimes measured by a photoconductive method and by diode reverse recovery compare favorably with furnace annealing data, and capacitance transient spectroscopy reveals a low density of defects in the junction depletion region. These results combined with the inherent advantages of low cost and high efficiency make Rapid Thermal Annealing ideally suited for VLSI device fabrication.
Rapid Annealing of Ion Implanted Silicon Structures using a Radiant Light Source
Authors: Harrison H.B. , Grigg M. , Short K. T. , Williams J.S. , Zylewicz A.
Published: March 2011

ABSTRACTA

simple radiant light source has been employed to rapidly anneal ion implanted silicon structures at temperatures >1000° C for times of the order of 1–200 sec. Rutherford backscattering and channeling analysis indicated good crystalline lattice recovery and the formation of metastable solid solutions of Sb in Si without observable diffusion broadening of the implanted profile. Diode arrays have been successfully annealed using the technique, with no observable deterioration of the surrounding oxide mask.
The Reaction Kinetics of Liquid 60/40 Sn/Pb Solder With Copper and Nickel: A High Temperature X-Ray Diffraction Study
Authors: Dehaven Patrick W.
Published: March 2011

With proper sample preparation, high temperature x-ray diffraction can be used to study in-situ the reactions occurring at a solder/metal interface. We have applied this technique to an investigation of the reaction kinetics between copper and nickel metal and 60/40 Sn/Pb solder. The copper and nickel are shown to follow similar pathways, each having a complex reaction profile that involves an initial “hold” of little reactivity, followed by a two-step diffusion controlled reaction. Activation energies were obtained from Arrhenius-type plots, and result in values of 6.8 kcal/mole for the nickel/solder reaction, and 13 kcal/mole for the copper/solder reaction. These results are compared with those obtained by previous investigators, and discussed in terms of the growth of the different intermetallic phases.
Dependence of Cu/Sn and Cu/60Sn40Pb Solder Joint Strength on Diffusion Controlled Growth of Cu3Sn and Cu6Sn5
Authors: Dunn D. S. , Marinis T. F. , Sherry W. M. , Williams C. J.
Published: March 2011

The growth of intermetallic compounds and the strength of Cu/ Sn and Cu/ 60Sn40Pb butt joints were studied as a function of isothermal aging. The effects of single-crystal (100), (110), and (111) oriented copper on the growth rates of Cu3Sn and Cu6Sn5 intermetallic compounds are characterized and the influence of elevated temperature aging on the tensile strength of butt joints analyzed. Substrate orientation appears to influence the growth rate. Metallographic measurements showed that the intermetallic compounds grew at a rate proportional to the square root of time. Tensile tests of aged butt joints revealed a more complex time dependence.
Thermomechanical Relaxation of Thin-Film Metallizations
Authors: Hieber Hartmann
Published: March 2011

Pure Al and Cu films evaporated on thin glass and thermally oxidized silicon substrates are subject to changes in temperature Ṫ>100Ks-1. With constant temperature the stress relaxation is between 1 and 10 % of the thermally induced stress. The stationary creep rates are comparable to diffusion controlled power-law creep. The discontinuous grain growth during the T cycling shifts the transient amplitudes and the stationary slopes of stress to negative values. DC resistance measurements indicate the production and annihilation of vacancies.
Characterization of the Adherence of Metals to Ceramics by a Fracture Mechanics Concept
Authors: Suga Tadatomo , Elssner Gerhard
Published: March 2011

The adherence and the bond strength of metal-to-ceramic joints are described in terms of the fracture energy Gcand the fracture resistance Kc. Small three- or four-point bend test specimens of 30 to 60 mm length notched or precracked at the metal-ceramic interface are used to determine the Gcand Kcdata. Examples of bond strength measurements on metal-to-ceramic joints and plasma-sprayed ceramic layer-metal substrate combinations aim to demonstrate the applicability of the method.
The Microstructure of Copper Films Deposited by E-Beam Evaporation onto Thin Polyimide Films
Authors: Wetzel J. T. , Smith D. A. , Appleby-Mougham G.
Published: March 2011

Copper was deposited by electron beam evaporation onto both freshly cleaved bare and polyimide-coated (001) NaCl at substrate temperatures of 20°, 100°, 200° and 300°C at rates of 2 and 20,Åsec−1. For all substrate temperatures and deposition rates investigated, the Volmer-Weber mode of film growth was observed for copper both on polyimide and on NaCl. Comparisons of film growth on the two substrates for a constant substrate temperature revealed differences in film thickness at which copper became continuous or formed a completely coalesced film. It was found that copper grown on polyimide formed continuous and completely coalesced films at smaller film thicknesses than on NaCI. However once a completely coalesced film was obtained, grain growth in the copper films proceeded more rapidly on NaC1 substrates than on polyimide substrates.
On the Selection Rules for the Identification of “Special” Interfaces
Authors: Wolf D.
Published: March 2011

It is demonstrated that the most important geometrical parameter governing the identification of “special” interfaces is the interplanar spacing of the lattice planes parallel to the interfacial plane and not, as often assumed, the inverse density of coincident-site lattice points, Σ. A simple geometrical selection rule for the identification of “special” or “favored” boundaries is formulated on the basis of the interplanar lattice constant.
Overview of Hybrid Circuits
Authors: Berg Morris
Published: March 2011

This presentation will review the development of hybrid circuit technology, a technology which is now widely accepted for all types of electronic products. The industry has matured and is predicted to show steady growth in the future.
Successful Design of New Very Low Thermal Expansion Ceramics
Authors: Roy Rustum , Agrawal D. K.
Published: March 2011

In the last few years we have succeeded in developing three separate groups of near-zero-expansion ceramics. These are based on: (1) Modification by crystalline solution of GeO2 for SiO2 in the well-known cordierite phase. (2) Discovery of a new structural family known as [NZP] or [CTP], many members of which have near-zero values of a and very extensive crystalline solution possibilities permitting continuous control of α. (3) Di- (or multi) pfiasic composites of phases, one with negative and one with positive a to give a net-zero-α ceramic material.
Corrosion Protection of at Alloys by Solution Cast Ta2O5
Authors: Lin Yeong C. , Wellinghoff Stephen T.
Published: March 2011

A newly developed amorphous, corrosion resistant Ta2O5 coating in saturated H2/H2O/Cl2 environment was studied by scanning and transmission electron microscopy and surface spectroscopy. Although Ta2O5 films formed on polished Al single crystal surfaces by sputter deposition of Ta and subsequent anodization effectively prevent the Al from corrosion by water saturated with chlorine, Al alloy surfaces are not protected, since the anodic film formed over grain boundaries, processing lines, and emergent Precipitates is poorly adherent, thus providing loci for corrosion. This problem was eliminated by casting a 400Å layer of tantalum oxyhydroxide polymer from ethanol solution onto the Al alloy substrate and curing to a Ta2O5 layer that effectively resisted attack by wet chlorine.
Synchrotron Section Topographic Study of the Denuded Zone Formation in Annealed Silicon
Authors: Tuomi T. , Tilli M. , Anttila O.
Published: March 2011

High resolution section topographs are made with synchrotron radiation using exposure times that are 1/1000 or less of those necessary with conventional x-ray sources. The imaging technique is employed to study oxygenrelated defects and their spatial distribution in a large number of annealed p-type (100) Czochralski silicon wafers. A two-step annealing in nitrogen consisted of a nucleation cycle at 800 °C and at 825 °C for 20 h followed by a denuding cycle at 1100 °C for 6 h. Denuded zones measuring from zero to 100 μm are seen in the synchrotron section topographs made after oxidation of the wafers at 1100 °C for 2 h. The denuded zone formation is found to depend strongly on the part of the crystal from which the wafer is cut. The wafers have the same interstitial oxygen concentration but different carbon concentrations. Large spatial variations up to 100 μm of the denuded zone width are observed in some wafers. Synchrotron section topographs of the wafers in which CMOS devices were fabricated showed a denuded zone only if the wafers were thremally annealed before the IC process.
Surface Steps on α-Alumina Films
Authors: Morrissey K. J. , Carter C. B.
Published: March 2011

Thin films of α-alumina have been produced by annealing oxide films produced by the thermal oxidation of aluminum substrates. Grains of αalumina which formed in the basal orientation show well-defined surface steps. When these steps move they interact with particles which have nucleated on the surface. Further annealing allows direct observation of the movement of these surface steps.
Grain Boundaries in NiO
Authors: Merkle Karl L. , Reddy J. F. , Wiley C. L.
Published: March 2011

Defocus-imaging and high-resolution electron microscopy (HREM) are used to study tilt grain boundaries (GB) in NiO near the <001> axis over the whole range of possible misorientation. Faceting and structural periodicities within facets are observed in high- and low-angle GBs. A reduced atomic density at high-angle GBs is suggested by the defocus behavior.