bluuebunny/crossref_metadata_2025 huggingface dataset:
The Accurate Determination of Bulk Glasses and Glass Film Compositions by Inductively Coupled Plasma-Atomic Emission Spectronmtry
Authors: Kometani T. Y.
Published: March 2011

A sequential inductivly coupled plasma-atomnic emission spectrrnetric (ICP-AES) method has been dewvloped for the cnmplete quantitative analyses of silicate glasses. B, P, Ge, and Si have been determined with 2%precisicn and accuracy in bulk glass and glass films on Si wafer substrates. Two chemical sample processing steps, dissdution in hydrofluoric acid at roam temperature and fusion in a sodium carbonate flux, were equally effective for deconposing samples without loss of volatile components. Rapid analysis for controlling glass film composition during IC process devlopment wer provided by the ICP-AES maethod. Where accurate film w~ghts were not obtainable, coatpositions wee established by complete analyses of all glass components except cxygen. The sum of the weights of components converted to their cides served as the sample weight for calculation purposes.
Physico-Chemical Characterization of Alumina Sols Prepared From Aluminum Alcoxides
Authors: Olson William L.
Published: March 2011

Alumina sols derived from aluminum sec-butoxide (Yoldas) were characterized. The distribution of the polymer sizes within the sol, determined by gel filtration chromatography (GFC), was found to be dramatically affected by small changes in the chemical processing or preparative procedure. Aging the sol at room temperature for two weeks produced no significant change in the GFC elution curves of the alumina sol. Sols with a “milky” appearance were found to exhibit a wider distribution of polymers by GFC than transparent sols. Rotary evaporation of the sol followed by redissolution of the residue was found to change the polymer size distribution described by the gel filtration elution curves. These observations coupled with 27Al NMR spectroscopy and viscometry measurements were used to elucidate the effects of process conditions and aging on the molecular structure of the sol.
Raman Spectroscopic Studies of Titanium Alkoxides Using UV Excitation
Authors: Payne Mark J. , Berglund Kris A.
Published: March 2011

The use of Raman spectroscopy can be greatly hindered by the presence of fluorescing impurities. Even at low concentrations, fluorescence can completely obscure the Raman signal. In the current study, Raman spectra were recorded for various titanium alkoxides (ethoxide, isopropoxide, isobutoxide) as a function of concentration and laser excitation wavelength. It has been shown that fluorescence can be avoided by using uv-excitation (363.8 nm). In addition, titanium alkoxides exhibit a preresonance Raman enhancement as the excitation wavelength appreaches the UV. This result is confirmed by a uv-visible absorption spectrum of the isopropoxide.
Precipitation Kinetics of the Titanium Isopropoxide Hydrolysis Reaction
Authors: Hartel R. W. , Berglund K. A.
Published: March 2011

The precipitation product of the titanium isopropoxide (TiPT) hydrolysis reaction was followed using photon correlation spectroscopy. This technique followed the mean size of the precipitate as the reaction progressed, as well as giving an indication of the number of particles being produced. From this analysis, the induction time for the onset of nucleation, nucleation rate (or the rate of particle production) and mean growth rate were correlated with reactant concentrations. In the concentration ranges studied, it was found that the induction time was a very strong inverse function of the reactant concentrations. Both nucleation rate and average growth rate were found to increase very rapidly as reactant concentration increased, with the TiPT concentration being more important. This reaction was also followed using absorbance spectrophotometry in the 500 to 320 nm range. After mixing of the reactants, an absorbance peak was seen between 330 and 335 nm, depending on the conditions. This peak increased slowly during the induction period and then increased rapidly after the onset of nucleation due to the increasing turbidity.
New Magnetic Materials Produced By The Sol-Gel Process: A Possibility Of Producing Exotic Devices
Authors: Kordas G.
Published: March 2011

Ferromagnetic resonance (FMR) spectra of an iron-oxide thin film with a thickness of 70 A were recorded between 100 and 410 K at 9.5 GHz after heat treatment at about 500 °C in hydrogen atmosphere. The FMR-signal of this film consisted of two components (A and B) when the film plane was oriented parallel to the external fieTp The intensity of these components is not proportional toT3/2 in the range from 100 to 410 K. The line width of the A-component is determined by inhomogeneities in the magnetic structure. The line width of the B-component may be influenced by the spin-spin relaxation mechanism and skin effect. The temperature behavior of the resonance field of the A- and B-components was tentatively attributed to variation of the local fields with the temperature of measurements.
Non-Conventional Route To Glass-Ceramics For Electronic Packaging
Authors: Gensse C. , Chowdhry U.
Published: March 2011

This paper describes a non-conventional route to formation of dense glass-ceramics at relatively low temperatures. Organometallic precursors were used to synthesize powders with controlled purity and stoichiometry in the MgO/Al2 O3 /SiO2 system. These amorphous powders sintered by viscous flow to form a dense glass below 1000°C. Further heating resulted in the formation of very fine grained glass-ceramics. Beta-quartz, cordierite, and cordierite-mullite glass-ceramics were obtained with attractive properties for electronic packaging.
Synthesis, Structure And Applications Of TiO2 Gels
Authors: Livage J.
Published: March 2011

TiO2 gels are usually obtained through hydrolysis of titanium alkoxides. Chemical additives can however react with the precursor at a molecular level and therefore modify the hydrolysis-condensation reactions. Several examples will be described :acetic acid, acetylacetone or Cr(acac)3 The whole solgel process is followed all the way from the precursors to the gel and each step is characterized by spectroscopic experiments (Infra-red, N.M.R, E.S.R.). Some electronic properties of TiO2 gels are then described. Chemical additives allow an optimization of the sol-gel process according to each specific applications : electrochromic display devices, photoanodes or photochemical reactions.
Characterization Of Sol-Gel Derived Tantalum Oxide Films
Authors: Silverman L. A. , Teowee G. , Uhlmann D. R.
Published: March 2011

We have studied the densification and dielectric properties of sol-gel derived tantalum oxide thin films as the insulators in MIS capacitors. Hydrolysis of tantalum ethoxide is extremely rapid and goes to completion in ethanol. Condensation is also rapid, and goes to completion in toluene Multiple layers were applied by spin-coating up to thicknesses of 3000 Å before cracking of the coating during drying ensued. Densification occurs from room temperature to 450 C, with the original film thickness decreasing by about half in one hour at 450 C. No additional densification occurs upon heating to 750 C. The dielectric constant decreases from unfired samples to those fired at 450 C, and then increases on firing from 600 to 750 C. The value of the dielectric constant at 1 MHz for samples fired at 750 C for one hour is 20, similar to that of anodically grown Ta2O5. Leakage currents as low as 2 × 10−7 amp cm−2 have been measured for applied fields of 200,000 V cm−1.
Innovative Chemical/Ceramic Directions
Authors: Morgan P. E. D.
Published: March 2011

I have attempted herein to show that relatively simple chemistry is available for much needed application to ceramic technology. The literature, as exemplified in the second section, already contains much more usable information than generally supposed. We need, too, a revival in simple inorganic chemistry.
Thermal. Acoustical and Structural Properties of Silica Aerogels
Authors: Fricke J. , Reichenauer G.
Published: March 2011

Silica aerogels either in monolithic or in granular form provide excellent thermal insulation and thus may be used as superinsulating spacer in all kinds of window systems. Highly porous aerogels also are exciting acoustic materials with sound velocities in the order of 100 m/s and acoustic impedances between 104and 105kg/(m2·s). Silica aerogels produced from TMOS seem to consist of massive primary particles (ø ≅ 1 nm, ρ ≅ 2000 kg/m3) which form secondary particles (ø ≅ 5 to 6 nm, ρ ≅800 kg/in3) displaying fractal properties (D≅ 2). The further buildup creates the highly porous low-density structure which is responsible for the special thermal, acoustical and optical properties of aerogels. Above about 100 nm, transparent aerogels should be homogeneous.
Synthesis of Metal Sulfide Powders From Organometallics
Authors: Johnson Curtis E. , Hickey Deborah K. , Harris Daniel C.
Published: March 2011

Organometallic reagents have been examined for the low-temperature preparation of metal sulfide powders which are desired as precursors to optical ceramics. The general approach is typified by the reaction of diethylzinc with hydrogen sulfide in toluene solution at room temperature. Electron microscopy shows that the white ZnS product consists of aggregates of ≤ 0.1 μm particles. The product is further characterized as predominantly cubic zinc sulfide (X-ray diffraction) which contains some residual hydrocarbon. Various organozinc reagents and experimental procedures have been tried in order to optimize the reaction. The reaction has also been extended to organometallic complexes of Al and Mg, and also to a ternary system, ZnAl2 S4
Precipitation of Monodisperse Ceramic Particles; Theoretical Models
Authors: Calvert Paul
Published: March 2011

Monodisperse ceramic powders with sizes in the range of 0.1-μm have been prepared by a number of groups. Generally a dilute solution of a metal compound is hydrolysed to produce amorphous, spherical particles which may be crystallized by subsequent heat treatments. Emulsion polymerization can produce similarly monodisperse latices if the polymerization conditions are carefully controlled. This paper discusses models of the precipitation process which are based on crystallization from aqueous solutions but are believed to be more generally applicable. From simulations it is concluded that monodisperse particles are a most unlikely outcome of a batch precipitation process. Surface active compounds could play an important role in controlling particle size. Inhomogenous mixing during the early stages of reaction should also be important.
Direct Process Metal Alkoxides as Ceramic Precursors
Authors: Ayen R. J. , Burk J. H.
Published: March 2011

Metal alkoxides have great promise as oxide ceramic precursors. Direct manufacture from the metal and the alcohol permits the production of high purity materials and of those alkoxides which cannot be easily obtained by other routes. Examples which are of great interest to ceramics are the alkoxides of silicon, aluminum, magnesium and yttrium.

Currently, only tetraethyl silicate is produced in large volumes by the direct route, employing a catalytic continuously fed process, yielding a distilled product. The reactivity of silicon, aluminum, magnesium and yttrium is governed by the metal surface state and activation and varies with different catalysts and alcohol chain length and branching.

The major use of tetraethyl silicate is in partially hydrolyzed form as binder for precision casting molds and zinc-rich primer coatings. Judicious choice of alkoxide ligands allows the manufacture of soluble or liquid Si, Al, Mg, and Y derivatives. These are especially suitable for molecular doping and mixing in the manufacture of yttriastabilized zirconia, mullite, spinel, cordierite and other oxide ceramic precursors.
An Equation for Melting and Freezing Transition Rates
Authors: Bucksbaum Philip H. , Thompson Michael O.
Published: March 2011

Statistical thermodynamics is used to derive the reaction rate for melting and freezing by considering an atomically sharp interface with or without an activated intermediate state. The resulting predictions differ substantially from those of the classical kinetic rate theory at large deviations from equilibrium. The model may be appropriate for the analysis of pulsed laser melting experiments where large deviations are expected.
Phase Selection During Pulsed Laser Annealing of Fe-V Alloys
Authors: Perepezko J. H. , Follstaedt D. M. , Peercy P. S.
Published: March 2011

Pulsed laser melting of the low-temperature σ (tetragonal, D8b) phase has been used to generate a liquid undercooled with respect to the melting point of the higher-temperature, equilibrium α (bcc) solid solution in equiatomic Fe-V alloys. From calculations based on reported thermodynamic data and equilibrium transformation temperatures, the metastable melting point of the σ phase is about 1720 K for an Fe-50 at.% V alloy, which is 54 K below the melting temperature of the α phase. During rapid heating of well-annealed σ-phase material with a 30 ns laser pulse to above melt threshold, the σ → α reaction is suppressed, so that the melt zone is undercooled by ∼ 54 K with respect to the equilibrium α phase. The α phase nucleates from the undercooled molten surface layer and is retained during the subsequent rapid cooling (∼ 1010K/s) because of the relatively sluggish α → σ transformation. X-ray diffraction (Read camera) and TEM identified the α phase in the near-surface after melting σ with incident laser energies (1.0–1.41 J/cm2) which are well above the melt threshold as determined by changes in reflectivity (∼ 0.7 J/cm2). The α phase nucleated from the undercooled liquid within ∼ 20 ns.
Fundamentals of Picosecond and Femtosecond Laser Solid Interactions
Authors: Kurz H.
Published: March 2011

The current understanding of the interaction between ultrashort laser pulses and condensed matter is demonstrated on a few selected samples. Hot electronic carrier relaxation in GaAs, plasmon aided recombination in highly excited silicon and ultrafast energy transport in metals are discussed.
Crystallization of Indium Implanted Amorphous Silicon
Authors: Nygren E. , Williams J. S. , Pogany A. , Elliman R. G. , Olson G. L. , McCallum J. C.
Published: March 2011

The annealing behavior of In+-implanted amorphous Si layers is reviewed. Particular attention is given to the amorphous to polycrystalline transformation for peak In concentrations > 0.5 atomic percent. New data concerning the transformation rate, associated In transport and microstructure are presented and phase transformation mechanisms are discussed.
Ion Irradiation Induced Metastable Phase Formation in the Al-Zr System
Authors: Lilienfeld David A. , Mayer J. W.
Published: March 2011

The Al-Zr system was investigated in an effort to form quasicrystals. While no quasicrystals were found, a metastable phase previously formed only by annealing of a metastable solid solution was observed. This phase was formed by thermal annealing or by elevated temperature ion irradiations of thin film specimens. This work is the first observation of ion irradiation induced formation of this metastable phase.
Precipitation of Kr In Ni at Room Temperature
Authors: Birtcher R. C. , Liu A. S.
Published: March 2011

The fluence dependence of Kr precipitation in Ni at room temperature has been studied with the aid of Transmission Electron Microscopy. As in other metals, the Kr precipitates in small cavities. Electron diffraction demonstrates that the Kr precipitates are solid, fcc crystals aligned with each other and the Ni lattice. The trends are similar to those observed for Kr precipitation in Al at room temperature. The average Kr lattice parameter, determined from the electron diffraction, increases with increasing Kr fluence from 0.515 nm to an asymptotic value of 0.545 nm. The asymptotic limit is due to the melting of the larger Kr precipitates. The mismatch between the Kr and Ni lattices is as large as 55%. Diffuse electron scattering was observed from large, liquid Kr precipitaes. This occurs for Kr fluences above 5.1020 Kr+ m-2 in Ni and above 2.5.1020 Kr+ m-2 in Al. At room temperature, the largest solid Kr precipitate observed in dark field images was 8.3 nm in diameter compared to 4.7 nm in Al. The larger precipitates are liquid or gas. The solid Kr metals at the same lattice parameter in both Ni and Al suggesting that the melting is thermodynamic in nature and independent of the host material.
Precipitation of Krypton in an Amorphous Ti-Cr Alloyc.
Authors: Allen W. , Birtcher R. C.
Published: March 2011

Results of a TEM investigation of the microstructural changes produced by the room temperature implantation of energetic Kr+ ions into a glassy Ti-Cr thin film are reported. As in other metals, the Kr precipitates as solid crystallites. The precipitation of crystalline Kr is accompanied by ultrafine crystallization of the metal host around each Kr crystal. With increasing fluence, the Kr precipitates grow to a critical size at which they melt, and the adjacent fine metal crystals disappear. A new TEM imaging technique is described briefly which utilizes the small angle electron scattering fine structure and which in principle is capable of revealing all fine particles simultaneously.
Solid Phase Epitaxial Regrowth of Implanted III-V Materials and Alloys
Authors: Licoppe Christian , Nissim Yves. I. , Meriadec Christelle , Henoc Pierre , D'Anterroches Cecile
Published: March 2011

The amorphous-crystalline (with residual defects) transition is studied in several III-V binary semiconductors and a ternary alloy. Regrowth shows the same behaviour in all cases. The growth kinetics are thermally activated and the activation energies have been measured using time resolved reflectivity measurements. Correlation with vacancy migration characteristic energy is discussed. In the particular case of GaAs, high resolution electron micrograph of the growth front are displayed. They show a rough microscopic structures together with larger scale smooth deformations, attributed to diffusion instabilities.
The Roles of Energetic Displacement Cascades in Ion Beam Modifications of Materials
Authors: Averback R. S. , Kim S. -J. , Rubia T. Diaz de la
Published: March 2011

The roles of energetic displacement cascades are ubiquitous in the fields of radiation damage and ion beam modifications of materials. These roles can be described on two time scales. For the first, which lasts ≈ 10-11 s, small cascade volumes are characterized by large supersaturations of point defects, structural disorder, and energy densities in excess of some tenths of eV's per atom. During this period, the system can be driven far from equilibrium with significant rearrangement of target atoms and the production of Frenkel pairs. Experimental studies of ion beam mixing in conjunction with molecular dynamics computer simulations, have contributed largely toward understanding these dynamic cascade processes. At later times, the microstructure of the material evolves as cascades begin to overlap, or at elevated temperatures, point defects migrate away from their nascent cascades. It will be shown how the primary state of damage in cascades influences this microstructural development. Examples involving radiation-enhanced diffusion and ion-induced amorphization will be discussed.
Studies of a Phenomenological Model of Ion Mixing
Authors: Cheng Y. -T. , Workman T. W. , Nicolet M -A. , Johnson W. L.
Published: March 2011

The phenomenological model of ion mixing based on the concept of a thermal spike and chemically biased diffusion is further developed. Experimental results available to date are compared with the model.
Investigations of Low-Temperature Epitaxy, Ion Damage, and Reactive-Ion Cleaning Utilizing Ion Beam Deposition
Authors: Appleton B. R. , Zuhr R. A. , Noggle T. S. , Herbots N. , Pennycook S. J.
Published: March 2011

The technique of ion beam deposition (IBD) is utilized to investigate low-energy, ion-induced damage on Si and Ge; to study reactive ion cleaning of Si and Ge; to fabricate amorphous isotopic heterostructures; and to fabricate and study the low-temperature epitaxial deposition of 74Ge on Ge(100), 30Si on Si(100), and 74Ge on Si(100). The techniques of ion scattering/channeling and cross-sectional TEM are combined to characterize the deposits.
Mesotaxy: Formation of Buried Single-Crystal CoSi2 Layers by Implantation
Authors: White Alice E. , Short K. T. , Dynes R. C. , Garno J. P. , Gibson J. M.
Published: March 2011

Using high dose implantation of 200 keV Co ions followed by high temperature annealing, we have created buried layers of CoSi2 in crystalline Si of both (100) and (111) orientations. For a dose of 3 × 1017 Co/cm2, the layer that forms is ∼1100Å thick and the overlying Si is ∼600Å thick. A lower dose of 2 × 1017 Co/cm2 yields a thinner layer, 700Å thick, under 1200Å of crystalline Si. Rutherford Backscattering and channeling analysis of the layers shows that they are aligned with the substrate (χmin of the Co as low as 6.4%.) and TEM inspection of the (100) CoSi2/Si interfaces shows that they are abrupt and epitaxial (with occasional small facets). Moreover, electrical characterization of these layers yields resistance ratios that are better than epitaxial CoSi2 films grown by more conventional UHV methods.
Systematics of Silicide Formation by High Dose Miplantation of Transition Metals into Si
Authors: Namavar F. , Sanchez F. H. , Budnick J. I. , Fasihuddin A. H. , Hayden H. C.
Published: March 2011

We have systematically studied the formation of transition-metal thin films by high dose (up to 1018 ions/cm2) implantation of Ti, V, Cr, Mn, Fe, Co, Ni and Nb at room temperature and 350°C into Si <100>.

For implantation at 350°C, our results, as obtained by Rutherford backscattering, X-ray diffractometry and Read Camera measurements, indicate that one can categorize these metals into two groups:

1.

a chromium group which includes V, Cr, Nb, Ti and Mn. Metals V, Cr and Nb form compounds (VSi2, CrSi2. NbSi2) with a hexagonal structure of the CrSi2 type whereas Ti and Mn both form compounds (Ti5Si3, Mn5Si3) with a hexagonal structure of the Mn5Si2 type.

2.

an iron group which includes Fe, Co and Ni. These metals form compounds (FeSi, CoSi, NiSi) with a cubic structure of the FeSi type.

In this paper the experimental results for Cr and Fe implantation at room temperature and 350°C will be discussed.
Ion-Induced Growth of Whiskers on Sn Films
Authors: Poker D. B. , Schubert J. , Stritzker B.
Published: March 2011

Whiskers have been observed to form on thin films (1000–2000 Å) of Sn following implantation of 20-keV H or He at temperatures below 150 K. The morphology of the whiskers following growth was examined using scanning electron microscopy (SEM) to illuminate the possible growth modes. In an effort to obtain support for either of several models of the growth process, the region near the base of the whiskers was examined for evidence of depletion or extrusion. No evidence of depletion was observed. The whiskers could be classified into two types: those that were supported on pedestals, a short transition region at the base of the whisker; and those without pedestals, which rose abruptly from the film with no transition. A novel structure has been observed on Sn films that were coated with 500 Å of Au/Pd to enhance the SEM image. The structure consists of a thin, planar surface several microns in length, oriented perpendicular to the substrate. The structures did not appear immediately after coating, but were present after storage in air for one month.
Growth Mechanisms During Thin Film Crystallization From the Melt
Authors: Pfeiffer Loren , Gelman A. E , Jackson K. A. , West K. W
Published: March 2011

We develop a model that appears to account for the existence of a new mode of crystallization recently discovered during zone-melt-recrystallization (ZMR) of silicon thin films on SiO 2 using a scanned strip heater or lamp. Transition to the new crystallization regime is induced by reducing the temperature of the scanned upper heater strip, thus reducing dT/dy, the thermal gradient along the direction of scan at the silicon solidification front. If dT/dy ≤:4 K/mm, the single crystal films have long non-branched subboundaries with tilt misalignments of 0.1 or less, a lateral separation in excess of 50 µm, and consist of rows of short dislocations threading through the film thickness and terminating at the two SiO2 layers. This is in marked contrast to material ZMR scanned at higher dT/dy which shows conventionally branched 1 to 3 subboundaries that consist of edge dislocations running in the plane of the film often for several hundred microns.

Our model extends the {111} faceted-freezing-front picture we have developed previously to take into account the freezing profile with respect to film thickness, and in particular to such profiles at the intersections of pairs of {111} facets where subboundaries are known to form. We propose that the melt-freezing interface profiles at these interior corner intersections are aligned approximately normal to the scan in the high gradient case, but become tilted towards the plane of the SiO2 cap layer for the low gradient case. This tilting accounts in a natural way for the transition from in-plane to threading dislocations.
Solidification Interface Morphologies in Zone Melting Recrystallization
Authors: Im J. S. , Thompson C. V. , Tomita H.
Published: March 2011

Using in situ optical microscopy we have studied the morphology of the liquid-solid interface during zone melting recrystallization. We have observed a variety of interface morphologies, each of which corresponds to specific types and distributions of subboundaries in the solidified material. We have also observed a variety of morphologies for stationary interfaces. We propose that perturbations in both the stationary and moving liquid-solid interfaces develop, at least in part, due to the spatial gradient in the radiation intensity in the region of the interface.
Origin of Subboundary Formation in Encapsulated Recrystallized Si Films on SiO2
Authors: Kamgar Avid , Nakahara S. , Knoell R. V.
Published: March 2011

We have made extensive microdiffraction studies of the crystallographic orientation of recrystallized (001) Si films, and transmission electron microscopy (TEM) analysis of dislocations at the initiation sites of the subboundaries. The microdiffraction studies reveal a characteristic folding behavior between the subgrains with an increasing tilt angle in the direction away from the initiation sites. The TEM results show straight dislocations along the [110] direction initiating from the nucleation site, the appearance of curved dislocations, and buckling of the epi film around the nucleation site, all indicative of a strong bending force at the initiation site. These two predominant characterististics of the recrystallized films, i.e., (1) crystallographic orientation of the subgrains, and (2) subboundaries together with their associated defects can be successfully interpreted in terms of the model which we recently proposed for the subboundary formation.
The Role of Implant Temperature in the Formation of Thin Buried Oxide Layers
Authors: White Alice E. , Short K. T. , Pfeiffer L. N. , West K. W. , Batstone J. L.
Published: March 2011

From the early work on high dose oxygen implantation for buried SiO2 formation, it is apparent that the temperature of the Si substrate during the implant has a strong influence on the quality of both the SiO2 layer and the overlying Si. This, in turn, can be related to the damage from the oxygen implant. For substrate temperatures < ∼ 300°C, amorphous Si is created during the implant and leads to the formation of twins or polycrystalline Si during the subsequent high temperature (>1300°C) anneal. At higher substrate temperatures (<∼400°C), dynamic annealing eliminates the amorphous Si, but the implanted oxygen appears to segregate during the implant leading to oxygen-rich amorphous regions imbedded in regions of crystalline material. As the amorphous regions start to coalesce and form SiO2 during the high temperature anneal, they trap crystalline Si which cannot escape by diffusion. This process can be circumvented by using a randomizing Si implant to change the damage structure from the oxygen implant before annealing. We have seen these effects clearly in sub-stoichiometric implants, and believe they are also operative during stoichiometric implants.
Characterization and Evolution of Microstructures Formed by High Dose Oxygen Implantation of silicont
Authors: El-Ghor M. K. , Pennycook S. J. , Sjoreen T. P. , Narayan J.
Published: March 2011

High doses of oxygen were implanted in silicon to produce stoichiometric buried oxide structures. Microstructural analysis was performed using transmission electron microscopy, electron energy loss spectroscopy, and Rutherford backscattering/channeling techniques. Cavities were observed in the top silicon layers of the as-implanted samples in two forms: spherical cavities (30–300 Å in diameter) in the first 1000 Å below the surface, followed by a 500 Å wide lamellar array of elongated cavities. A post implantation annealing was carried out at temperatures between 1150°C and 1250°C for 3 h during which the cavities became faceted and a denuded zone of 400 Å was formed. However, with a 1300°C anneal the cavities disappeared and the density of the two prominent types of defects, namely precipitates (mostly amorphous, but occasionally crystalline) and dislocations, decreased significantly. The silicon-oxide interface became increasingly planar. Possible mechanisms of annealing of the cavities, the precipitates, and the associated planarization of the interface are proposed.
A Study of the Effects of Implantation Dose and Annealing Temperature on the Formation of Buried Nitride SOI Structures
Authors: Kerger M. B. , Kwor R. , Zeller M. , Hemment P. L. F. , Reeson K. J.
Published: March 2011

Nitrogen implantation into single-crystal silicon can result in a buried nitride layer under proper processing conditions. SOI structures have been formed using this technique. The optimum parameters for forming a buried nitride layer with good insulating characteristics have been investigated. Nitrogen was implanted into <100> silicon at 200 keV at an implantatipp tem erature of 500°C. The effect of implantation doses of 1.05 × 1018N+/cm2, 1.3 × 1018N+/cm+ and 1.4 × 1018N+ /cm+ and post-implantation annealing temperatures of 1050, 1100, 1150, and 1200°C on the buried nitride layer was studied. Transmission Infrared Spectroscopy was used to determine the structure (amorphous or crystalline) of the buried nitride layer. The infrared spectra change as a function of annealing temperature, indicating the transition from amorphous to crystalline silicon nitride. Leakage currents through the structures were measured and SEM micrographs of the nitride surfaces were taken. The correlation between the IR results and these data will be presented.
Rapid Thermal Annealing of Ni/Al/Si and Ni/Si Systems
Authors: Katz A. , KOMEM Y.
Published: March 2011

The effect of Rapid Thermal Annealing on phase formation and diffusion processes in the Ni(30 nm) /Al(10 nm)/Si system was studied and coxpared to a Ni(30 nm)/Si reference system. Heat treatments were carried out at temperatures between 400°C and 900°C for 2 seconds.

The results obtained by means of TEM, AES and XRD indicated that the Ni/Al/Si system underwent a local melting in the intermediate Al layer at the Al/Si eutectic temperature (577°C). This reaction, due to the rapid melting process, resulted in formation of a unique layered-structure composed of a columnar polycrystalline layer (60 nm thick) of Ni2Si and NiSi adjacent to the Si substrate with relatively smooth interface and an outer layer of two separate polycrystalline films (both about 10 m thick) of Al3Ni (inside) and Ni(Al0.5Si0.5 ) (outside). Under the same rapid thermal processing conditions the Ni/Si reference system underwent a solid state reaction which resulted in the formation of a polycrystalline layer (60 nm thick) composed of Ni2Si and NiSi as well as NiSi2.
The Effects of Processing Ambient on the Reaction Rate of Ti and Si Using Rapid Thermal Processing
Authors: Kermani A. , Farnam K. , Stultz T.
Published: March 2011

The reaction rate of sputter deposited Ti films on c-Si as a function of process ambient was studied. Sintering temperatures ranging from 600 to 1100° C, under pure ammonia, forming gas, nitrogen and argon were used. The additional effect of a reactively sputtered TiN cap on the reaction rate was also investigated. Processed films were then analyzed using AES, RBS and four point probe resistivity mapping. It was found that for temperatures below 700° C, an ammonia ambient has the most pronounced effect on reducing the rate of formation of titanium silicide, followed by forming gas (N 2/H2 10% vol), nitrogen and argon. Additionally, the presence of the TiN cap further reduced the reaction rate while exhibiting significant diffusion of nitrogen into the silicide film. For the samples annealed in ambients containing nitrogen, a thin layer of Tix Ny was simultaneously formed on top of the silicide film. The thickness and Stoichiometry of this titanium nitride films were then correlated with the sintering temperature and ambient. The details of these findings and their impact on the formation of the self-aligned titanium silicide (salicide) will be presented.
Uniform Tetragonal WSi2 Layers Formed by RTA
Authors: Siegal M. , Santiago J. J. , Spiegel J. Van Der , Graham W. R. , Setton M.
Published: March 2011

Thin films of tungsten silicide with resistivities of 30 – 35 μΩ-cm have been formed by sputter depositing 71 nm of W metal onto (100) oriented, 5 Ω-cm, p-type silicon wafers that were etched in BOE 500 solution. The samples were fast radiatively processed in an RTA system under high vacuum for time anneals ranging from 15 – 50 seconds at a temperature of ∼ 1100°C. The inevitable oxide barrier at the interface is shown to decrease with increasing RTA time.
Effectiveness of Thin Film Encapsulants for Reducing Evaporation during Rapid Thermal Processing of GaAs
Authors: Haynes T. E. , Picraux S. T. , Chu W. K.
Published: March 2011

A technique is described for direct measurement of evaporation of Ga and As from capped GaAs during RTP. Application of this method to the study of Si, SiO2, and Si3N4 caps with thicknesses of 20 nm to 60 nm provides a direct measure of the temperature ranges for which the caps are able to prevent evaporation during RTP. In addition, kinetic studies of the evaporation at slightly higher temperatures provides information useful for establishing the predominant evaporation mechanism. For the encapsulants studied, these measurements indicate that the observed evaporation is due to formation of cracks in the film during the initial 10 sec of RTP.
The Effect of Implantation and Annealing Conditions on the Fe Profile in Semi-Insulating InP.
Authors: Bahir G. , Merz J. L. , Abelson J. R. , Sigmon T. W.
Published: March 2011

The Fe depth distribution has been measured in semi-insulating (SI) InP implanted with Si as a function of implant temperature and post-implant annealing technique (either furnace annealing or rapid thermal annealing). Depth profiles obtained by secondary ion mass spectrometry and Rutherford backscattering measurements of the damage demonstrate that Fe redistributes into regions of residual damage during thermal processing. These results are interpreted in terms of implantation-related damage effects and the stoichiometry imbalance induced by the Si implantation.
Mechanisms for the Deposition of Thin Metallic Films by Laser Driven Gas Phase Reactions
Authors: Jervis T. R. , Menon S. K. , Joyce E. L. , Carroll D. W.
Published: March 2011

Gas phase processing rakes laser deposition over large areas possible but homogeneous nucleation of large atomic clusters must be avoided if films are to be produced. Clusters can be highly variable in size from a few atoms to significant fractions of a micrometer. If conditions do not allow for complete quenching of the clusters produced in the gas phase, these clusters can arrive at the substrate with sufficient energy to self sinter into homogeneous films which are substantially different from metallic films grown by thermal techniques. Using transmission electron microscopy (TEM), we have characterized the microstructure of thin metallic films deposited by laser breakdown chemical vapor deposition and identified a range of deposition conditions which can lead from powders to homogeneous polycrystalline films and mixed phase materials. Gas phase nucleation is dependent on reactant partial pressures and the gas phase quench rate which car be varied in part by adjusting the H2 content of the source gas. Manipulation of these parameters can vary powder size from about one micrometer to less than 2 nanometers. Variation of the quench rate during the deposition of polycrystalline films varies the grain size in the films. heating the substrate drastically changes the conditions under which the film is formed and as a consequence, can radically alter the microstructure of the film itself.
Laser-Induced Deposition of Gold Micropatterns from Metallopolymer Thin Films: A Photochemical Approach
Authors: Houlding V. H. , Clements N. S. , Beeson K. W. , West G. A.
Published: March 2011

The deep ultraviolet (250 nm) photopatterning of spin-on films of polymeric Au mercaptide results in formation of adherent Au patterns. Fxcimer laser projection patterning and standard contact printing techniques give excellent pattern resolution on the micron scale. Laser direct write produces lines at very fast writing speeds. Exposed areas are less soluble than unexposed areas, i.e. the film behaves as a negative photoresist. Bakeout of developed patterns at 250°C yields good purity Au micropatterns up to 500 Å thick. Mechanistic information about pattern formation is gained from uv-visible, infrared, and mass spectrometric monitoring of the photolysis process, and from Auger analysis of films. Adherent patterns are apparently formed by photochemical cleavage of Au-S bonds followed by evaporation of a small amount of free mercaptide. The loss of ligand in the exposed areas renders them less soluble than unexposed film. Thermal decomposition of both photolyzed and unphotolyzed films has the same result of volatilizing all film material except Au.
UV Laser-Induced Metal Deposition on Semiconductors From Electroplating Solutions
Authors: Zahavi Joseph , Pehrsson Pehr E.
Published: March 2011

We have demonstrated metal deposition on semiconductors immersed in electroplating solution by exposure to UV laser radiation. N-type β-SiC and Si in gold or Pd/Ni electroplating solutions were exposed to 20 ns pulses of 193 nm or 248 nm excimer laser radiation. The energy per pulse was 20–100 mJ. Au and Pd/Ni metallizations deposited in lines and circles on SiC showed leaky Schottky barrier I-V characteristics. The thickness increased with increasing pulse energy or number. Both masked and maskless deposition were demonstrated without apparent damage to the substrate. Details of the process, potential mechanisms, and sample characterization are discussed.
Characterization of Excimer Laser Deposited Gaas Films From the Photolysis of Trimethylgallium and Trimethylarsine At 193 nm
Authors: Mccrary V. R. , Donnelly V. M. , Brasen D. , Appelbaum A. , Farrow R. C.
Published: March 2011

The growth of GaAs thin films from the excimer laser photolysis of trimethylarsine (TMAs) and trimethylgallium (TMGa) at 193 nm is reported. Scanning electron microscopy (SEM), electron channeling, Rutherford backscattering spectroscopy (RBS), transmission electron microscopy (TEM), and Auger electron spectroscopy (AES) were used to characterize the films. Incident laser fluences on the surface of 0.096–0.115 J/cm2 lead to carbon desorption, adatom mobility, transient annealing and hence epitaxial growth. However, TEM micrographs also revealed the growth of GaAs twins along the <110> direction in a novel periodic fashion, with a spacing equal to that of the ArF excimer laser wavelength (193 nm). Time-resolved mass spectrometry, used to determine gas-phase photolysis products created during the deposition process, showed that AsCH3 and higher gallium-alkyls are significant products which transport As and Ga to the surface.
Excimer Laser Assisted Deposition of GaAs, AlAs, and [Al.Ga]as from Lewis Acid-Base Adducts
Authors: Zinck J. J. , Brewer P. D. , Jensen J. E. , Olson G. L. , Tutt L. W.
Published: March 2011

Laser-assisted deposition of GaAs, AlAs and [AIGa]As thin films on Ge(100) substrates from trimethylgallium-trimethylarsenic and trimethylaluminumtrimethylarsenic Lewis acid-base adduct source materials is reported. A parametric study has been performed in which reactive gas pressure, substrate temperature, laser fluence, laser wavelength (248 nm or 193 nm). and orientation of the laser beam with respect to the substrate have been varied. In the case of irradiation parallel to the substrate, stoichiometric films of GaAs and [AIGa]As have been obtained. The data suggest that for irradiation perpendicular to the substrate a competition exists between desorption and photodeposition, which adversely affects film stoichiometry under the conditions studied.
Laser Stimulated Deposition of GaAs, GaAsP and GaAsP-GaAs Superlattices
Authors: Karam N. H. , Bedair S. M. , El-Masry N. A. , Griffis D.
Published: March 2011

An Ar+ ion laser has been used for direct writing of GaAs and GaAsP single crystal films on thermally biased GaAs substrates. Multiple scanning of the laser beam at speeds in the range 100–200 μm/s at carefully selected growth conditions resulted in single crystalline selectively deposited films. Photoluminescence indicates that these deposited films have optical properties that are comparable with the conventionally (MOCVD) grown material.
Laser beam irradiation has been used to form a superlattice (SL) structure which has been demonstrated in the GaAsP-GaAs system. When a GaAs substrate is exposed to fluxes of AsH3, PH3 and TMG at 500°C, only GaAs will be deposited because of the insufficient cracking of PH3. However, localized laser heating results in GaAsP deposition. A GaAsP-GaAs superlattice with a period of about 400 Å has been synthesized. This laser induced technique can thus have potential applications in the generation of abrupt interfaces without the use of shutters as in MBE or gas switching as in MOCVD.
Real-Time Studies of Laser Oxidation of Copper: Characteristics of an Optical Heat Source
Authors: Baufay L. , Houle F. A. , Wilson R. J.
Published: March 2011

Oxidation of copper films is carried out using a cw argon ion laser. Time-resolved reflectance measurements during the reaction are performed at probe wavelengths of 632.8 and 514.5 nm. Strong temporal variations in reflectance are observed, and are attributed to interference within the growing oxide film. Measurements carried out as a function of laser power are complemented by Auger electron and scanning electron microscopy. A theoretical model of the system has been developed which treats its optical and thermal properties and the film growth process in an integrated way. The calculations highlight the intimate connection between the time dependence of the optical properties of the metal-metal oxide system and the film growth rate. The highly non-isothermal conditions which prevail account for the rapid rate of oxidation relative to furnace oxidation. Although both laser and furnace oxidation are thermal processes which obey a parabolic rate law, preliminary oxygen pressure dependence data indicate that they may not have the same rate determining step.
Synthesis of Diamond by Laser-Induced CVD
Authors: Kitahama K. , Hirata K. , Nakamatsu H. , Kawai S. , Fujimori N. , Imai T.
Published: March 2011

Synthesis of diamond thin-films has been tried by an ArF excimer laser-induced chemical vapor deposition (LCVD) technique, using acetylene diluted with hydrogen as a source gas and a silicon wafer as a substrate. In these experiments, irradiation geometry, substrate temperature and laser power density were varied. Upon irradiation by a focused laser beam, deposition of diamond on substrates heated above 400°Cwas observed, and was confirmed by reflection electron diffraction (RED) photographs. Homogeneity of the diamond films was improved by irradiation parallel to the substrate. These facts suggest that the formation of diamond proceeds through multiple photon decomposition of the reactant gas, and that electronic excitation of gas phase rather than that of substrate or adsorbate layer is essential to form diamond.
Catalyzed Gaseous Etching of Silicon
Authors: Selamoglu N. , Mucha J. A. , Flamm D. L. , Ibbotson D. E.
Published: March 2011

Etching of silicon by molecular fluorine is accelerated when trace quantities of copper are present on the surface. Copper is a residue formed when sputter-deposited aluminum (containing 0.5 % copper) is selectively removed by HF from the silicon surface. The temperature dependence of the etching rate was studied in the range 60–290°C. At temperatures higher than 80°C copper causes a ˜100-fold increase in the rate of etching of the underlying silicon (100), compared to unmetallized samples. Above 180°C, F2 exhibits a higher absolute etch rate than equivalent concentrations of fluorine atoms. Preliminary results for other metal contaminants and etchant gases indicate that silver also accelerates F2 etching, and copper enhances etching by NF3. The results are interpreted in terms of a catalytic mechanism.
Cl2 Reactive Ion Beam Etching of Heavy n-Type Si
Authors: Krueger E. Eric , Ruoff Arthur L.
Published: March 2011

The etch yield vs n-type doping level up to 1.5 × 1021 As/cm3 was measured. Also, the etch yield as a function of ion energy (300 to 1500 eV) for the heaviest doped samples (1.5 × 1021 As/cm3) was measured. Only a small 10–15 percent enhancement in etch rate over low doped silicon was observed. Channeling experiments with Rutherford backscattering spectrometry showed 84 percent of the arsenic atoms were in substitutional positions in the silicon crystal. In addition, silicon was implanted with arsenic to a dose of 1.25 × 1017 #/cm2 and then laser annealed. This produced samples with a 5000 angstrom layer of uniformly doped silicon at five atomic percent. Channeling experiments showed these samples to have 82 percent of the dopant in substitutional sites. Samples were then masked with chrome and etched at varied pressures, temperatures and ion energies. Within our experimental resolution no isotropic etching was observed. This small doping dependence of the etching behavior of n-type silicon in reactive ion beam etching suggests that the rate limiting step for Cl2 RIBE is different than for Cl2 RIE, rf-plasma and laser assisted etching. A discussion of this difference is given assuming a much lower concentration of atomic chlorine in RIBE.
A New Method for Analyzing Thin Sidewall Inhibitor Layers
Authors: McVittie J. P. , Lin T. A. , Bariya A. J.
Published: March 2011

Etch inhibitor layers are the key to anisotropy for a number of dry etch processes, yet little is known about these layers because of the difficulty in analyzing them on the side walls where they form. In this paper we will show that an Al grid suspended above an etching surface can be used to suppress ion bombardment and allow the inhibitor to form on large horizontal surfaces which can be easily analyzed. The effect of ion bombardment on the nature of the inhibitor layer can also be elucidated using this technique. In conjunction with X-ray Photoelectron Spectroscopy, this method was used to look at the polymeric inhibitor formed during Si etching in SF6/C2CIF5 with and without the presence of photoresist.