bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymeric Precursor Synthesis of Ceramic Materials
Authors: Eror Nicholas G. , Anderson Harlan U.
Published: March 2011

For the past twenty years we have successfully synthesized a wide range of ceramic materials by using organic precursors. The organic precursors are formulated into a glass before pyrolysis. Synthesized compounds include, for example, titanates, zirconates, silicates, chromites, niobates, tantalates, ferrites and molybdates.

This preparation technique is based upon having individual cations complexed in separate weak organic acid solutions. The individual solutions are gravimetrically analyzed for the respective cation concentration to a precision of 10–100 ppm. In this way it is possible to precisely control all of the cation concentrations, and to mix the ions on an atomic scale in the liquid state. There is no precipitation in the mixed solution as it is evaporated to the rigid polymeric statein the form of a uniformly colored transparent glass. The glass retains homogeneity on the atomic scale, and may be calcined at a relatively low temperature of only a few hundred degrees Celsius to the homogeneous single phase of precise cationic stoichiometry and particle size of a few hundred Å.

The advantage of having such well characterized, thermodynamically defined compounds is illustrated by the resulting understanding of the solid state chemistry of multicomponent compounds that has occurred.
Dispersion of Ceramic Particles in Organic Liquids
Authors: Calvert P. D. , Lalanandham R. R. , Parish M. V. , Fox J. , Lee H. , Pober R. L. , Tormey E. S. , Bowen H. K.
Published: March 2011

Good dispersion of oxide ceramics in organic solvents can be achieved using many different dispersants. Several types of dispersants, including fatty acids, coupling agents, polar aromatic compounds and polymers, are discussed to illustrate the important phenomena. Many new problems arise in actual slips during ceramics processing; these are briefly discussed.
The Gel Route to TiO2 Photoanodes
Authors: Doeuff S. , Henry M. , Sanchez C.
Published: March 2011

Cr3+ and Al3+ doped TiO2 can be easily made via the sol-gel process. Mixing the metal-organic solutions give rise to a random dispersion of the doping ions into the TiO2 network. Amorphous and crystalline phases have been characterized all the way from the gel to the crystalline products by thermal analysis, X-ray diffraction, vibrational spectroscopy and E.S.R. Organic groups appear to be involved in the formation of the gel network and could lead to a better control of the morphology of the xerogel. A thermal stabilization of the anatase phase, up to 900°C, is observed when Cr3+ is introduced as a dopant. This would lead to the preparation of anatase TiO2 photoanodes.
Dielectric Properties Of Sol - Gel Silica Glasses
Authors: Chandrashekhar G. V. , Shafer M. W.
Published: March 2011

Dielectric properties have been measured for a series of porous and fully densified silica glasses, prepared by the sol-gel technique starting from Si-methoxide or Si-fume. The results for the partially densified glasses do not show any preferred orientation for porosity. When fully densified (∼2.25 gms/cc) without any prior treatment of the gels, they have dielectric constants of ≥ 6.5 and loss factors of 0.002 at 1 MHz, compared to values of 3.8 and <0.001 for commercial fused silica. There is no corresponding anomaly in the d.c. resistivity. Elemental carbon present to the extent of 400–500 ppm is likely to be the main cause for this enhanced dielectric constant. Extensive cleaning of the gels prior to densification to remove this carbon were not completely successful pointing to the difficulty in preparing high purity, low dielectric constant glasses via the organic sol-gel route at least in the bulk form.
Crystallization Of Oxide Films Derived From Metallo-Organic Precursors
Authors: Chen K. C. , Janah A. , Mackenzie J. D.
Published: March 2011

Ferroelectric lead zirconate titanate and ferrimagnetic nickel ferrite films were prepared by dip-coating of metal organic solutions. In the amorphous state, both films were porous, with specific porous surface areas on the order of tens of square meters. Crystallization temperatures were in the range of 400–500°C. The crystallization kinetics of the porous films and powders of both compounds have been studied by using non-isothermal DSC and isothermal XRD. The kinetic parameters were empirically described by the Johnson-Mehl-Avrami transformation equation α = 1- exp(−Ktn). The order of reaction (n) of PZT film is approximately 1 but that of the powder is 2, and their activation energies are 80 and 70 kcal/mole, respectively. It was found that the PZT film crystallizes more easily than the powder at the same temperature. The nickel ferrite film and powder, on the other hand, have similar n values ranging from 0.6 to 0.7, with activation energies of 20 and 35 kcal/mole, respectively. The possible mechanisms were also briefly discussed.
Preparation of A12O3-ZrO2 Composites by Adjustment of Surface Chemical Behavior
Authors: Baik S. , Bleier A. , Becher P. F.
Published: March 2011

Aqueous colloidal routes for processing binary suspensions containing Al 2 O 3 and ZrO2 were designed and tested in order to achieve homogeneous microstructures. Effects of particle size and size ratio of each component, pH, and electrolyte concentration of composite suspensions on sedimentation, green density, and ZrO2 distribution in sintered microstructures were examined. The pH conditions for inhibiting differential sedimentation without impairing green density were optimized. Overall suspension and coagulation behavior for these composite systems were explained using the DLVO approach. Optimum balance of colloidal and gravitational forces occurred when the secondary minimum heterocoagulation was maximized.
Silicon Carbide From Organosilanes and Application in Silica Gel Glass Composites
Authors: Lee Butrand I. , Hench L. L.
Published: March 2011

Several organosilanes were crosslinked and pyrolyzed to produce silicon carbide (SiC). Use of chemical crosslinking agents required lower temperatures and shorter times for curing and increased SiC char yields. Impregnating the silanes into sol-gel derived silica monoliths followed by crosslinking and pyrolysis resulted in hard and tough SiC/SiO2 composite bodies.
Synthesis of Submicron, Narrow Size Distribution Spherical Zincite
Authors: Heistand Robert H. , Chia Yee-Ho
Published: March 2011

Zincite has been produced by the controlled hydrolysis of an alkylzinc alkoxide (ethylzinc-t-butoxide) resulting in ∼0.2 μm spherical particles with a narrow size distribution consisting of 150 Å crystallites. The surface area is 30 m2/g. Variation of the concentration of the water drastically affects the particle and crystallite sizes. The results of a systematic study of the hydrolysis parameters are reported here.
Preparation of Ceramic Powders From Emulsions
Authors: Akinc Mufit , Richardson Kerry
Published: March 2011

Yttrium oxide powders were prepared from water-in-oil type emulsions by loading the yttrium ions into the aqueous phase. Emulsions were characterized with respect to droplet size and distribution, emulsion type, and time and temperature stability. Precursor powders were obtained from the emulsions by evaporation of the aqueous phase in a hot oil bath. Powder characteristics, such as size, shape, composition, and sinterability as a function of procedural variables, were determined. The new technique appears to be practical and may be economically feasible.
Solid Phase Superheating During Picosecond Laser Melting of Gallium Arsenide
Authors: Von Der Linde D. , Fabricius N. , Danielzik B. , Bonkhofer T.
Published: March 2011

The velocity distributions of atoms evaporated from the surface of GaAs during laser heating with nanosecond and picosecond pulses are measured. The atomic velocities provide information about the surface temperature. For picosecond heating we observe a continuous transition of the temperature across the melting point, whereas for nanosecond heating the melting point is marked by a distinct plateau of the temperature curve. From these observations we conclude that the solid is strongly superheated during picosecond irradiation. A detailed analysis suggests superheating of typically a few hundred degrees above the melting point.
Transition-State Model for Entropy-Limited Freezing
Authors: Tsao J. Y. , Aziz M. J. , Peercy P. S. , Thompson M. O.
Published: March 2011

A brief review is given of transition-state theory, both for the case of unimolecular reactions in the gas phase, and for reactions in condensed phases. An argument is made that, within the context of this theory, heterogeneous freezing in Si is limited to rates much lower than collision rates by the difference between the entropies of the solid and the liquid.
Time-Resolved and Post-Irradiation Studies of the Interaction of High-Power Pulsed Microwave Radiation with Silicon
Authors: James R. B. , Bolton P. R. , Alvarez R. A. , Valiga R. E. , Christie W. H.
Published: March 2011

We have measured the microwave-induced damage to the near-surface region of silicon for 1.9-μs pulses at a frequency of 2.856 GHz and a pulse power of up to 7.2 MW. Rectangular samples were irradiated in a test section of WR-284 waveguide that was filled with freon to a pressure of 30 psig. Incident, transmitted and reflected powers were monitored with directional couplers and fast diodes. The results of the time-resolved optical measurements show that the onset of surface damage is accompanied by a large increase in the reflected power. Examination of the irradiated surfaces shows that the degree of damage is greatest near the edges of the samples. Using secondary ion mass spectrometry to profile the implanted As, we find that the microwave pulses can melt the near-surface region of the material for pulse powers exceeding a threshold value.
Ion Emission During Low Fluence KrF Laser-Metal Interaction
Authors: Ying Q. Y. , Kwok H. S.
Published: March 2011

A KrF laser was used to produce ions from an aluminum surface. The threshold energy fluence was found to be ∼30 mJ/cm2 which was lower than similar studies on the ablation of metals. The measured threshold however, was of the same order of magnitude for atomic desorption from semiconductor surfaces. This process can be used to perform surface analysis without ablation damage.
The Effect of Cooling Rate During Rapid Solidification on the Structure and Texture of NiTi
Authors: Pedraza A. J. , Godbole M. J. , Kenik E. A. , Pedraza D. F. , Lowndes D. H.
Published: March 2011

A study has been conducted on the effects of increasing cooling rate during rapid solidification of NiTi upon the phases that are produced. The hammer and anvil rapid solidification technique and laser melting with a nanosecond excimer laser were used, which allow the cooling rate to be varied by three to four orders of magnitude. Although 1/3 {110} superlattice reflections are seen in the selected area diffraction (SAD) patterns of the splat quenched (SQ) specimens, x-ray diffraction analyses show the presence of only B2 phase and martensite. On the other hand, laser treatment (LT) of the specimens produces a layer that has a L10 structure with a slight monoclinic distortion. This phase can be envisaged as a small distortion of a B2 unit cell with a volume per atom ~3.3% lower than the equilibrium B2 phase. Also martensite is present in the layer. SQ alloys exhibit a marked {200} texture due to columnar growth opposite to the direction of heat extraction, while LT produces epitaxial regrowth of the melted layer. No substantial disordering is obtained in NiTi rapidly solidified alloys.
Crystallization of Amorphous 55wt%Cr-45wt%Ni Films Induced by 60 ns (0.694 μm) Single Laser Pulse
Authors: Ursu I. , Bîrjega M. I. , Constantin C. A. , Dinescu M. , Mihailescu I. N. , Pogrion N. Popescu , Ketskemety I. , Szill E.
Published: March 2011

Amorphous 55wt%Cr-45wt%Ni films (60 nm thick) supported on EM copper grids were irradiated in air at normal incidence with a ruby laser (λ∼, 0.694 μm) through a ≈ 1.5 mm diameter diaphragm using one single laser pulse of 60 ns (FWHM) with fluences ranging from 120 to 540 J.m−2. The structure of the irradiated films is studied by TEM and TED. As a rule due to the appearance of thermal gradients between the centre and the mesh edge of the EM grid, the crystallization took place under various conditions of reaction from liquid phase, liquid melted layers , activated diffusion in solid state, to under threshold conditions for the development of the crystalline nuclei in the amorphous matrix. Periodic resonant and unreso-nant structures also developed in the liquid melted layers.
Laser Interactions with Optical Recording Materials
Authors: Marinero Ernesto E.
Published: March 2011

Laser-material interactions are pivotal to optical storage technology. Laser quenching and thermomagnetic processes form the memory basis for approaches based on “phase-change” materials and magneto-optical alloys respectively. Recent progress in phase-change materials indicates that compound semiconductors as well as single element materials are characterized by fast crystallization times. In this work we review, utilizing time-resolved optical and conductivity probes, the melt-kinetics and glass formation processes in Te thin films and the laser-induced crystallization of amorphous GeTe. The latter studies are complemented by x-ray diffraction and TEM analysis. Results are also presented on time-resolved Kerr rotation studies to investigate the magnetic domain formation kinetics in thermo-magnetic recording. Material research problems facing laser interactions with optical recording materials will be discussed.
Nanosecond Dynamics of Excimer Laser Induced Thermal Decompositon of Thin Polymer Films
Authors: Wu X. D. , Dijkkamp D. , Gozdz A. S. , Venkatesan T.
Published: March 2011

A novel method to study the effect of rapid heating on polymers is presented. Nanosecond time resolved reflectivity measurements of thermal decomposition of poly(3-butenyltrimethylsilane sulfone) (PBTMSS) and polymethylmetacrylate (PMMA) films spun on silicon wafers and irradiated by a pulsed excimer laser at 248 nm are reported. It was found that there exists a critical temperature for effective decomposition. The time scale for thermal decomposition is comparable with the time scales determined for photo-ablation processes. The results indicate that thermal effects are very important in the interaction between polymers and pulsed UV-lasers.
Nonequilibrium Interface Kinetics During Rapid Solidification
Authors: Aziz Michael J.
Published: March 2011

The deviations from local equilibrium at a rapidly moving solid-liquid interface are well documented. The fraction of solute atoms in the liquid at the interface that joins the crystal during rapid solidification approaches unity and the interface temperature drops. Experimental and theoretical work on impurity incorporation and interfacial undercooling is reviewed. Past and future experiments to test the theories are discussed.
Diffusion, Solubility and Segregation of Implanted Cu, Ag and Au in Amorphous Si
Authors: Jacobson D. C. , Elliman R. G. , Gibson J. M. , Olson G. L. , Poate J. M. , Williams J. S.
Published: March 2011

The diffusion of Cu, Ag and Au has been measured in implanted, amorphous Si, over the range 150–600° C. The diffusion coefficients are characterized by Arrhenius relationships with activation energies for Cu, Ag and Au of 1.25, 1.6 and 1.4 eV respectively. The solubility of Au in amorphous Si was measured to be 6 orders of magnitude greater than crystalline Si at a temperature of 515°C. The Cu, Ag and Au are segregated ahead of the moving amorphous-crystalline interface. The presence of Au can increase the velocity of the interface.
Formation Of Stable Point Defects in Ion-Implanted Si
Authors: Culbertson R. J. , Pennycook S. J.
Published: March 2011

Double doping of Si by ion implantation of both group V and group III dopants was studied. For the case of Sb as the group V dopant, both Sb and B could be maintained in solution after high temperature heat treatment at concentrations greatly exceeding their solubility limits. With Sb implantation alone, Sb diffusion takes place with a highly enhanced transient diffusion, followed by nucleation of self interstitials into loops at the projected range. In certain double-doped samples this projected range damage was eliminated. In the under-compensated B-Sb case, evidence of stable Sb-B pairs was obtained.
Neutralization Rates for Low-Energy Ions Scattered From Solid Surfaces
Authors: Eklund Elliott A. , Daley Richard S. , huang Judy H. , Williams R. Stanley
Published: March 2011

Calculations of the angular distributions of scattered ions were used to simulate impact collision ion scattering spectrometry (ICISS) experiments. The calculations were performed first for 2–keV Na+ ions incident on the Pt(111) surface in the <112> azimuth. The fitting of these calculations to the experimental data provided information about the surface structure of the sample and the trajectories of the incident ions. The inclusion of a first-order decay model for Auger neutralization with the calculations for Na+ allowed the simulation of 2-keV Ne+ ions in the ICISS mode on the same Pt surface. From these simulations it was possible to extract the Auger neutralization halflife for Ne+, found to be 1.30 ± 0.10 femtoseconds.
Temperature Dependence of Amorphization above 10K in the CuTi Intermetallic Compound Under Electron Irradiation
Authors: Koike J. , Oluzzi D. E. , Meshii M. , Okamoto P. R.
Published: March 2011

The critical dose required to amorphize the crystalline compound CuTi during irradiation with 1 MeV electrons has been investigated from 10 to 288 K. The results show that above a critical temperature (Tc) of about 185 K, CuTi remains crystalline and only defect clusters are formed. Below Tc, amorphization occurs with no observable cluster formation. The critical dose for amorphization was found to be temperature dependent below Tc: as the irradiation temperature increases, a higher dose is required to induce amorphization. This observation supports the concept that Tc corresponds to the vacancy migration temperature. Below Tc, interstitial migration may contribute to the observed reduction in the amorphization rate with increasing temperature.
Smooth Silicide Formation by Ion Beam Mixing of Ti/Si-Layers
Authors: Kohlhof K. , Mantl S. , Stritzker B.
Published: March 2011

Ion beam mixing experiments of Ti-Si layers have been performed with Kr ions of 250 keV energy and doses ranging from 7 1015 to 7 1016 cm-2 at temperatures between liquid nitrogen temperature and 450°C. At substrate temperatures below 120°C no silicide formation could be detected. Only weak mixing at the Ti-Si interface is observed. At temperatures above 120°C the formation of TiSi2 could be verified by Rutherford backscattering and X-ray diffractometry. Layers of TiSi2 produced by ion beam mixing show smooth surfaces in contrast to those prepared by conventional furnace annealing. Those display rough surfaces and interfaces.
Ion Beam Induced Amorphization and Crystallization Processes in Silicon and GaAs
Authors: Elliman R. G. , Williams J. S. , Johnson S. T. , Nygren E.
Published: March 2011

Thin amorphous layers in crystalline Si and GaAs substates have been irradiated at selected temperatures with 1.5 MeV Ne+ ions to induce either epitaxial crystallization or amorphization. In Si, such irradiation can induce complete epitaxial crystallization of a 1000 A surface amorphous layer for temperatures typically >200°C whereas, at significantly lower temperatures, layer-by-layer amorphization results. Although epitaxial crystallization can also be stimulated in GaAs by ion irradiation at temperatures >65°C, the process is non-linear with ion dose and results in poor quality crystal growth for amorphous layers greater than a few hundred Angstroms in thickness. Layer-by-layer amorphization has not been observed in GaAs.
The Effect of Self-Implantation on the Interdiffusion in Amorphous Si/Ge Multilayers
Authors: Park B. , Spaepen F. , Poate J. M. , Jacobson D. C.
Published: March 2011

Artificial amorphous Si/Ge multilayers of equiatomic average composition with a repeat length around 60 Å have been prepared by ion beam sputtering. Implantation with 29Si led to a decrease in the intensity of the X-ray diffraction peaks arising from the composition modulation, which could be used for an accurate measurement of the implantation-induced mixing distance. Subsequent annealing showed no difference between the interdiffusivity in an implanted and unimplanted sample.
Radiation Damage Induced Transient Enhanced Diffusion of Dopants in Silicon
Authors: Angelucci R. , Gabilli E. , Lotti R. , Negrini P. , Servidori M. , Solmi S. , Anderle M.
Published: March 2011

Transient enhanced diffusion is observed for P, As and Sb as a consequence of the recovery of the damage created by a silicon dose below the amorphization threshold. The phenomenon results more pronounced for low temperature furnace heating than after rapid thermal annealing and for those elements having a larger component of interstitialcy diffusion mechanism.

A close correlation was found between the trends of the anomalous dopant diffusion and the implant damage evolution analyzed by X-ray diffraction. This evolution takes place via interstitial cluster dissolution.
Dendritic Growth During Phase Transformation in Ni-Mo System Induced by Ion Beam
Authors: Liu B. X. , Huang L. J. , Shang C. H.
Published: March 2011

Multilayered Ni-Mo films were irradiated by 200keV Xe ions at room temperature to various doses. The beam current density was confined to be less than lμA/cm2 to avoid overheating. The experimental evidences from X-ray diffraction, electrical resistivity, as well 4 as Rutherford Backscattering, indicate that a dose of 7 × 1014/cm2 was the critical one for uniform mixing of the layers and amorphous phase formation in Ni65 Mo35 films. Under this critical dose, various dendritic patterns were formed as revealed by bright field transmission electron microscopy. The microscopic mechanisms of the ion induced dendritic growth are attributed to the cluster formation and the aggregation of the formed clusters.
Radiation Defect-Induced Lattice Contraction of InP
Authors: Wie C. R. , Jones T. , Tombrello T. A. , Vreeland T. , Xiong F. , Zhu Z. , Burns G. , Dacol F. H.
Published: March 2011

We studied the lattice strain induced in the MeV ion bombarded InP crystals and the annealing behaviors of lattice strain, Raman line shift, and linewidth. The lattice spacing for the planes parallel to the surface decreases as a result of irradiation, and amounts to a strain of −0.061% for (100) face, −0.056% for (110) face, and −0.050% for (111) face for 15 MeV Cl bombarded samples to a dose of 1.25E15 ions/cm2. The negative lattice strain, Raman line shift, and line width completely recover at 450°C, and show a major recovery stage at 250°C – 350°C.
Study of Ion Implanted Copper Laser Mirrors by Spectroscopic Ellipsometry
Authors: Snyder P. G. , Massengale A. , Memarzadeh K. , Woollam J. A. , Ingram D. C. , Pronko P. P.
Published: March 2011

Implantation with 400 keV Ag or Cu ions improves the near-surface microstructural quality and reflectance of diamond turned and mechanically polished flat copper laser mirrors. Spectroscopic ellipsometry is sensitive to changes in either the microscopic surface roughness, or in the nearsurface substrate void fraction, and both parameters are observed to change upon implantation. Substrate density as a function of ion fluence peaks at about 5 × 10 15cm-2. Low energy (300 eV) Ar ion implantation can cause either a reduction or increase in microscopic surface roughness, depending on fluence.
Growth -Front Modulation in Lamp Zone Melting of Si on SiO2
Authors: Dutartre D. , Bensahel D. , Haond M.
Published: March 2011

We present 3 techniques of defect localization we have studied in order to produce Silicon On Insulator films obtained by Lamp Zone Melting. They consist in a periodical variation of the thickness of either the oxide cap, or the polysilicon film, or the underlying oxide layer. We compare the crystallographic quality of the resulting films and in-situ observations of the solidification front for each structure.
Microstructural Characterization of High Dose Oxygen Implanted Silicon
Authors: Batstone J. L. , White Alice E. , Short K. T. , Gibson J. M. , Jacobson D. C.
Published: March 2011

The microstructure of oxygen implanted silicon for use in silicon-on- insulator technology has been examined by transmission electron microscopy. A variety of buried oxide layers prepared using oxygen doses below and above that required for stoichiometric SiO2formation have been studied. High resolution imaging in crosssection has revealed exceptionally flat Si-SiO2interfaces, comparable to the best thermally grown Si-SiO2interfaces. Examination of as-implanted material shows a complex interwoven crystalline/amorphous structure which evolves during high temperature (1350–1400° C) annealing into a buried oxide layer.
New DSPEG Approach to Improvement of SOS Using Low Dose Self-Implantations
Authors: Richmond Eliezer Dovid , Knudson Alvin R. , Kawayoshi H.
Published: March 2011

A new approach is proposed for the material improvement of silicon-on-sapphire (SOS). This approach utilizes the phenomena that the defect elimination throughout the silicon layer depends on both the deep and shallow self-implantations of the double solid phase epitaxial growth (DSPEG) technique for SOS material improvement. The new aspects of this approach are that the deep implantation does not form an amorphous layer, and therefore the ion damage to the substrate is minimized eliminating Al autodoping of the silicon layer.
The Effect of Channel-Protect Oxide on Laser Recrystallized Silicon-on-insulator MOS devices.
Authors: Sritharan S. , Collins G. J. , Fukumoto J. , Szluk N. , Jones K. M. , Al-Jassim M. M.
Published: March 2011

Latchup free lateral CMOS transistors with PMOS devices in the laser recrystallized silicon and the NMOS devices in the bulk silicon were fabricated. One micron thick field oxide isolates the PMOS devices in the recrystallized silicon from the NMOS devices in the bulk wafer. The seed area for recrystallization was used for the fabrication of the NMOS devices. An oxide layer of 0.1um thickness was used to protect the channel region of the NMOS devices during the laser recrystallization. The effect of this channel protect-oxide is discussed and the characteristics of the NMOS devices with and without the channel protect oxide are compared.
Defect States Induced by Rapid Thermal Annealing in Virgin or Implanted Czochralski-Grown Silicon
Authors: Remram M. , Barbier D. , Joly J.-F. , Laugier A.
Published: March 2011

Defect state generation in either virgin or implanted CZ silicon has been investigated by means of capacitance transient spectroscopy (DLTS) after rapid thermal annealing (RTA), using an incoherent light furnace and variable cycle parameters. No electron traps were dectected with gold Schottky contacts made on virgin phosporous-doped silicon annealed for 5 sec at any temperature. On the otherhand 3 hole trap levels H1(0.45 eV), H2(0.29 eV) and H3(0.31 eV) have been observed in boron-doped silicon (Al Schottky contacts) after a 5 sec temperature plateau between 850 and 1050°C. Peak concentrations ranging from 1013 to 1014 cm−3 were measured after annealing at 1000°C for the three hole traps. By increasing the plateau duration up to 20 sec hole traps were no longer detected in boron-doped silicon. Furthermore in As+ or PF5+-implanted and rapidly annealed N+/P junctions the H3(0.31 eV) level was replaced by another hole trap H4(0.4 eV), which appeared within specific conditions (RTA parameters, implant dose and species). Moreover an electron trap E(0.55 eV) was only detected in the high dose As+-implanted junctions after annealing for 10 sec at 1100°C. The probable metallic origin of the observed defect states and the RTA parameter dependence of the hole trap concentrations suggest gettering and trapping in interstitial sites as possible mechanisms involved in RTA.
Laser-Induced Deposition of Gold
Authors: Baum Thomas H.
Published: March 2011

The laser-induced, vapor-phase deposition of gold metal from dimethyl-(2,4-pentanedionato) gold (III) and two fluorinated derivatives was examined by both photopyrolytic (LCVD) and photochemical modes of decomposition. High purity gold deposits are formed by LCVD with the rates of deposition being extremely vapor pressure dependent and thus, gold complex dependent. Photochemical deposition of gold patterns with 2 μm resolution can be achieved by irradiation of these complexes in the UV, but the deposited material is contaminated with carbon impurities.
Photo-CVD of Dielectric Films by a Microwave-Excited VUV Lamp
Authors: Tamagawa Kouichi , Hayashi Toshio , Komiya Souji
Published: March 2011

Silicon nitride and oxide films have been formed using a photo-CVD apparatus with a microwave-excited VUV lamp. The lamp used was a D2 lamp or a rare gas resonance line lamp such as Xe and Kr. For the nitride film deposited at 320 °C, the BHF etching rate of the film, 40–70Å/min, is lower by less than one-tenth than that deposited using a conventional low-pressure Hg lamp, indicating formation of a high density film. The deposition rate has been enhanced dramatically from 13Å/min to 100Å/min by incorporating the photo-ionization assisted effect, which is brought about by an ionization of a substrate surface and by ions formed by collisions of reactant gases with photoelectrons and photo-ionized ions. The BHF etching rate of the oxide film is considerably lower than those formed using a Hg lamp and excimer lasers, and is similar to that using conventional PE-CVD. Conformal step coverage has been obtained for both the silicon nitride and oxide films.
Influence of Ion Bombardment on the Nucleation and Growth of Plasna Deposited Amorphous Silicon
Authors: Antoine A. M. , Drevillon B.
Published: March 2011

Real-time spectroscopic phase modulated ellipsometry is used to study the influence of ion bombardment on the growth of plasma deposited amorphous silicon (a-Si:H). The influence of the relative ion flux impinging on the substrate is discussed by comparing a-Si:H films deposited in RF and multipole discharges. A nucleation process is observed in the early stage of the growth of a-Si:H deposited on chromium substrates. When the ion bombardment is strong (multipole plasma) a coalescence of the island structure is observed leading to the formation of a high density film with a smooth interface.
Direct-Writing of High-Aspect-Ratio Trenches in Silicon
Authors: Treyz G. V. , Beach R. , Osgood R. M.
Published: March 2011

Deep trenches have been etched in crystalline silicon with polarization-controlled, variable-curvature walls. Scan speeds of up to 10mm/s have been demonstrated. A model of the etching process has been developed which is based on a local, melt-enhanced etch rate. Comparisons of model predictions and experimental data are presented.
Fluorine Atom Production Mechanisms From COF2 and NF3 in Uv Laser Etching of Poly-Silicon and Molybdenum
Authors: Loper Gary L. , Tabat Martin D.
Published: March 2011

Ultraviolet laser-induced, radical-etching processes developed by us can provide practical etch rates and selectivities for most of the important film layer combinations used in silicon microelectronic devices. These processes have been demonstrated in simple proximity and projection exposure experiments to produce etch features on surfaces with dimensions of a few tenths of a micrometer.

Mechanistic studies suggest that, in our etching processes for polysilicon and molybdenum, fluorine atoms responsible for etching are primarily produced from the precursors COF2 and NF3 on the surface rather than in the gas phase. The predominant production process appears to be photodecomposition of surface adsorbed precursor. Contributions due to precursor pyrolysis or precursor reaction with photogenerated charge carriers are found to be unimportant.
A Mechanistic Study of the Interaction of Ultraviolet Laser Radiation with Low Density Polymers
Authors: Hargis Philip J.
Published: March 2011

Ultraviolet laser radiation at 248 nm and 266 nm was used to ablate low density (0.04 to 0.14 g/cm3) microcellular polystyrene and TPX foams at laser fluences between 0.1 and 1000 J/cm2, The dependence of the etch rate on laser fluence and foam density is consistent with a linear absorption mechanism for the initial stages of polystyrene ablation. Studies of the morphology and chemical composition of the ablated foams as a function of laser fluence and foam density show that the degree of melting increases at the higher foam densities. Blackbody and radical specie contributions to optical emission from the ablated foam were readily resolved for correlation with laser fluence, foam density, absorption spectra, and etch depth. Temperatures in excess of 3000 °K are calculated from emission spectra observed during the ablation of polystyrene foams. From this data we conclude that chemical and thermal changes in the ablated foam are influenced by the absorption spectrum as well as the density of the foam.
Reactions of Fluorine-Containing Compounds on Thermal SiO2
Authors: Joyce Stephen , Steinfeld Jeffrey I.
Published: March 2011

The reactivity of XeF2 and CF3 on thermally grown SiO2 surfaces has been investigated. CF3 radicals were generated by infrared multiple-photon dissociation of C2F6 using a pulsed CO2laser. X-ray photoelectron spectroscopy (XPS) was used to determine the chemical state of the surface after exposure to the gases. Both CF3 and XeF2 are relatively inert to annealed SiO2 surfaces.- Ion damaged surfaces are much more reactive. Implications for ion enhancement of etching are discussed. XPS spectra reveal fluorine, from XeF2 bonded to both silicon and oxygen. The CF3 radical appears to undergo little dissociation upon chemisorption on SiO2.
Chemically Assisted Ion Beam Etching of Tungsten using ClF3
Authors: Garner Charles
Published: March 2011

A chemically assisted ion beam etching (CAIBE) technique is described which employs an ion beam from an electron bombardment ion source and a directed flux of ClF3 neutrals. This technique enables the etching of tungsten foils and films in excess of 40 μm thick with good anisotropy and pattern definition over areas 5 mm2, and with a high degree of selectivity. (100) tungsten foils etched with this process exhibit preferred orientation etching, while polycrystalline tungsten films exhibit high etch rates approximately 80% that of (100) orientation tungsten.
The Effect of Hydrogen Ion Bombardment on Fluorocarbon Polymers
Authors: Cheeks Teresa L. , Ruoff Arthur L.
Published: March 2011

Polytetrafluoroethylene(PTFE), Polyvinylidene fluoride(PVFD), and Polymethylmethacrylate(PMMA) thin films have been bombarded with a H2 ion beam. The ion exposure time varied from 3 to 12 minutes corresponding to an ion dose of 1017H+/cm2 to 1018H+/cm2. ESCA spectra showed that the fluorine intensity from the fluorocarbon polymers decreased after H2 ion bombardment. Also the CF2 type bond groups observed in the fluorocarbon polymers decreased leaving only the hydrocarbon type bond groups (CH2) after H2 ion bombardment. We speculate that the hydrogen atoms abstract fluorine from the polymer which decreases the fluorine concentration. ESCA has been used to determine the effect of chemical vs. inert (H2 vs. He) ion bombardment on fluorocarbon polymers as a function of exposure time. The implication of these results to explain the differences between RIE and RIBE deposited polymers will be discussed.
Laser and Thermal Induced Reactions of Mo(CO)6, CH3CH2OH, and NO on Si(111)7 × 7
Authors: Ying Z. , Ho W.
Published: March 2011

Laser induced reactions of Mo(CO)6, CH3CH2OH, and NO adsorbed on Si(111)7 × 7 at 257 and 514 nm were studied and compared with thermally induced reactions under ultrahigh vacuum conditions utilizing laser induced desorption spectroscopy, thermal desorption spectroscopy, high resolution electron energy loss spectroscopy, and Auger electron spectroscopy. By using continuous wave laser irradiation, photolytic effects are clearly distinguished from pyrolytic effects. Mo(CO)6 and CH3CH2OH adsorbed on Si behave similarly as in the gas phase, whereas a substrate-mediated reaction channel is observed for NO adsorbed on Si.
Deposition of Iron on Si(111)-(7×7): Photo- and Electron-Assisted Decomposition of Fe(CO)5
Authors: Swanson J. R. , Friend C. M. , Chabal Y. J.
Published: March 2011

Laser- and electron-assisted deposition of Fe on Si(111)-(7×7) surfaces using decomposition of Fe(CO)5 has been investigated with multiple internal reflection Fourier transform infrared, Auger electron and temperature programmed desorption spectroscopies and low energy electron diffraction under ultra-high vacuum conditions. No thermal reaction was apparent in temperature programmed desorption experiments: only molecular Fe(CO)5 desorption was observed at temperatures of 150 and 170 K, corresponding to desorption energies in the range of 7–10 kcal./mole. Fe(CO)5 decomposition could be induced using either incident 1.6 keV electrons or ultraviolet photons. Significant amounts of carbon were deposited from the electron induced decomposition, consistent with earlier reports on the Si(100) surface. In contrast, ultraviolet photolysis did not result in any detectable incorporation of carbon or oxygen into the iron deposits. No partially decarbonylated Fe(CO)x, x<5, fragments were detected subsequent to exposure to photons using infrared spectroscopy. However, a new, unresolved low frequency shoulder did appear in the infrared spectrum after exposing the Fe(CO)5 covered Si(111)-(7×7) crystal to the electron beam. Iron photodeposition was evident in the Auger electron spectra obtained subsequent to photolysis and annealing of the surface to either 300 K or 1000 K in order to desorb unreacted Fe(CO)5. These data suggest that there are no surface stable Fe(CO)x, x<5, species in the photodeposition process. Instead, photolysis yields Fe atoms directly, even at low temperatures. Annealing to temperatures on the order of 1000 K subsequent to iron deposition resulted in a significant decrease in the Fe:Si ratio as measured by Auger electron spectroscopy. In addition, CO could not be readsorbed on a surface where the Fe(CO)5 had been decomposed. This is attributed to dissolution of Fe into the bulk silicon crystal.
Mechanism of IR and UV Laser-Induced Evaporation and Ablation From Condensed Molecular Systems
Authors: Hess Peter
Published: March 2011

The main features of evaporation of organic molecules from Van der Waals films with resonant IR photons and ablation of organic material and fragments from polymers with UV photons, resulting from time-of-flight experiments, are discussed. These results point to a photothermal mechanism. The experimental facts known so far can be explained using thermodynamic and kinetic arguments. No principal difference is found for breaking Van der Waals bonds with IR photons and chemical bonds employing UV photons.
Surface Chemical Reactions Stimulated by Low Energy Electron Bombardment
Authors: Kunz R. R. , Mayer T. M.
Published: March 2011

A low energy, broad beam electron source was used to induce chemical reactions on surfaces. Electron beam energies were selected to maximize the emission of secondary electrons, for the purpose of determining if these low energy electrons contributed to the overall reaction. Room temperature silicon oxidation showed maximum terminal oxide thickness (35 Å) at the primary electron energy that produced the maximum secondary electron flux (300 eV). XPS showed these films to be mostly sub-oxide in nature. Similar results were obtained in analogous experiments using tetraethoxysilane to deposit SiO2 and using iron pentacarbonyl to deposit Fe. By increasing the incident angle of the electron beam to 70 degrees from the normal, the deposition yields of SiO2 and Fe increased by 45% and 30%, respectively. This again was thought to be a result of secondary electron contributions, as the secondary yield increased by a factor of two upon tilting the beam.
Deposition of Low-Stress Encapsulants on InP and GaAs
Authors: Chakrabarti U. K. , Pearton S. J. , Barz H. , Vonneida A. R. , Short K. T. , Lee J. W.
Published: March 2011

AℓN deposited by D.C. triode sputtering and spin-on, phosphorus-doped glass (PSG) layers on GaAs and InP were investigated as encapsulants. These films have similar expansion coefficients to both GaAs and InP, minimizing the amount of strain induced in the near-surface region of the underlying wafer. We have quantified this effect by direct measurements of the stress in the films and by using secondary ion mass spectrometry profiling to measure the redistribution of Cr and Fe in encapsulated GaAs and InP respectively during high temperature processing. The dopant redistribution is considerably less for the AℓN and PSG films compared to the more conventional SiO2 and Si3N4 layers. The interaction of the films with the substrate at elevated temperatures is minimal as determined by Auger profiling and the electrical properties of the surface after removal of the encapsulants. The composition of the films remains essentially constant after annealing, as measured by Rutherford backscattering, and the thickness uniformity over large wafer diameters (2″) can be excellent with close control of the deposition parameters. The activation characteristics of low dose, Si-implanted layers in GaAs using either PSG or AℓN are comparable to those obtained using capless annealing or SiO2 or Si3N4 encapsulation.
Nonlinear Optical Study of Si Epitaxy
Authors: Heinz T. F. , Loy M. M. T. , Iyer S. S.
Published: March 2011

The applicability of the nonlinear optical technique of surface second-harmonic generation to in-situ studies of epitaxial and non-epitaxial crystal growth of centrosymmetric materials is demonstrated. In measurements of the deposition of atomic Si on Si(111)-7×7 surfaces, the (anisotropic) second-harmonic response is seen to be sensitive to the ordering of fractional monolayers of adatoms. For deposition on a substrate held at room temperature, the second-harmonic data are consistent with the formation of a disordered adlayer on top of the original reconstructed surface. The results of real-time measurements of the thermal annealing of disordered Si adlayers of monolayer thickness are also presented.
Cross-Sectional TEM Investigation of Low-Temperature Epitaxial Silicon Films Grown by Ultra-Low Pressure CVD
Authors: Yew T. R. , Comfort J. H. , Garverick L. M. , Burger W. R. , Reif R.
Published: March 2011

In this paper, cross-sectional TEM is used to investigate the quality of silicon epitaxial films grown by ultra-low pressure chemical vapor deposition at 750°C. The dislocation density and epi.- substrate interface width were investigated for different predeposition Argon sputter cleaning condltions. Epitaxial films with dislocation densities of less than 10 cm−2 and interfacial width of about 13 Å were obtained.
Photoinduced Topotaxial Exchange Reactions in Cadmium Sulphide Thin Films
Authors: Cumberbatch T. J. , Barden P. E. , Knightley J.
Published: March 2011

A CO2 laser, operating at 10.6μm, has been used to promote the growth of topotaxial layers of the chalcocite phase of cuprous sulphide in cadmium sulphide thin films immersed in an organic solution of a cuprous salt at ambient temperature. Cuprous sulphide growth is initiated by the laser beam which passes through the liquid and raises the surface temperature of the CdS allowing ion exchange to take place without changing the surface topography. An investigation into different combinations of organic solvents and cuprous/cupric salts has revealed that cuprous iodide in acetonitrile or propionitrile yields the fastest growth rates. The results are compared with those obtained from junctions fabricated using lasers operating in the visible frequency range.
Pyrolytic Laser Direct Writing of Nickel Over Polyimides
Authors: Bezuk S. J. , Baseman R. J. , Kryzak C. , Warner K. , Thomes G.
Published: March 2011

Polyimides are of great interest as insulators for microelectronic fabrication due to their low dielectric constant and planarizing properties. However, they are thermally sensitive films. Nonetheless, preliminary results clearly demonstrate that nickel lines readily can be laser-pyrolytically drawn over polyimide films.

While elevated laser power will damage underlying polyimide films, microelectronic quality nickel lines can be drawn using nickel carbonyl at relatively low laser intensities over polyimides with little or no change in the electrical characteristics. Polyimide's lower thermal conductivity relative to silicon dioxide facilitates increased nickel deposition rates. Self-limiting effects have been observed during the deposition that can lead to near microelectronically ideal line cross sections.
Properties of Diamondlike Carbon Films
Authors: Fujii K. , Yokota S. H. , Shōhata N.
Published: March 2011

Hard carbon films have been deposited onto room-temperature silicon substrates in a de plasma of methane and hydrogen. The substrates are placed on the cathode. A stainless mesh is held at the same potential as the cathode and is set above the substrates. Although the deposited films are amorphous and contain 24.4 atomic percent hydrogen, they have the following diamondlike properties: hardness is almost equivalent to that of natural diamond; electrical resistivity is on the order of 1013Ωcm; chemical inertness is excellent to acids; thermal diffusivity is 5.2 cm2 /sec. However, the films have a large compressive stress of 1.3×1010 dyn/cm2.

Annealed films exhibit dehydrogenation, graphitization, an increase in chemical reactivity, volume expansion and stress relaxation above 400°C. The activation energy for the transformation from the diamondlikephase to the graphitic phase is 18 kcal/mole.

The dependence of the thermal diffusivity and hydrogen content on both the CH4/H2 gas mix ratio and the total pressure have been measured for the films deposited in a dc plasma without the mesh.
Metallic Surface Modification Via Thermal Plasma Techniques
Authors: Giacobbe F. W.
Published: March 2011

A thermal plasma arc technique has been used to modify selected metallic surface and near surface properties at ambient pressures. This experimental study was implemented by treating several steel test specimens, at elevated temperatures, in a pure argon plasma and in two preblended argon/ active gas mixtures. One of the argon/active gas plasma mixtures produced significant chemical surface modifications in the steel test specimens treated in this atmosphere. Ions and free radical fragments, produced from the active gas, were responsible for the observed changes in the chemical composition of the steel surface. The other plasma treated specimens did not exhibit any changes in chemical specific details and results obtained, during this study, have been described.
Dry Etching Damage in GaAs and Al0.22Ga0.78As
Authors: Kirillov D. , Cooper C. B. , Powell R. A.
Published: March 2011

Reactive ion etching induced damage in GaAs and Al0.22Ga0.78As was studied using Raman spectroscopy. The phonon spectra of undoped materials allow evaluation of damage to the crystal lattice and the coupled plasmonphonon spectra of n-type material provide a sensitive probe of electrical characteristics. Studies were made of layers exposed to plasmas of Ar, SF6 and SiCl4. Conditions for low damage Ar plasma cleaning and for dielectric cap removal by SF6 were established. Etching in the SiCl4 plasma generally produced strong damage, although low damage etching was observed in a few cases.