bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low Temperature Synthesis of Carbide Thin Films by Pulsed Laser Deposition (PLD)
Authors: Donley M. S. , Zabinski J. S. , Sessler W. J. , Dyhouse V. J. , Walck S. D. , McDevitt N. T. 
Published: March 2011

ABSTRACTThin films of titanium carbide (TiC) and boron carbide (B4C) were grown by excimer pulsed laser deposition (PLD) at room temperature (RT) and 300°C. Films were deposited using the output of an excimer laser operating with KrF gas (γ = 248 nm, 15 ns pulse duration) to ablate hot-pressed targets. Film chemistry, morphology, and crystallinity were investigated. Stoichiometric, crystalline TiC films were grown on 440C stainless steel and NaCl substrates at room temperature and at 300°C. The films grown on NaCl were nanocrystalline, cubic TiC, with a grain size ranging between 2 and 10 nm in diameter. Boron carbide films were grown on silicon {100} substrates at room temperature and at 300°C. Film chemistry and stoichiometry duplicated that of the B4C target, which contained B4C and a mixed C-B-O-N binder phase. SEM analysis indicated that the morphology of the films was uniform, non-porous, and fine-grained. The films exhibited good adhesion and wear resistance, based on friction and wear data collected with a ball-on-disc tribometer.
Comparison in Surface Modifications of Sintered and Single Crystal Ceramic Targets After Laser Ablation
Authors: Young K. H. 
Published: March 2011

ABSTRACTA systematic study of the surface morphology and chemical composition of several ceramic targets after pulsed laser ablation has been conducted using a scanning electron microscope with x-ray energy dispersive spectroscopy. We have examined single crystal LaAlO3 and NdGaO3 disks, as well as powder sintered LaAlO3 and SrTiO3 discs. These targets were rotated during laser ablation and concentric trenches were formed with distinctive surface morphologies due to different doses of laser energy. We observed varied light-solid surface interactions on the targets prepared by different methods. The sintered targets exhibited surface explosions after long period laser ablation, presumably due to sub-surface overheating [1]. The single crystal targets have smoother surface morphology and the resulting films have much fewer particles on the surface. As such, they are preferred for laser ablation applications.
Heat Transfer in Laser Annealing of Semiconductor Films
Authors: CriGoropoulos C. P. , Xu X. , Taylor S. L. , Park H. K. 
Published: March 2011

ABSTRACTMelting and solidification of a silicon film by continuous wave laser beam irradiation has been studied. The silicon film melting and recrystallization is controlled by the temperature distribution in the semiconductor. Calculations have been carried out for a range of laser beam parameters and material translational speeds. The results for the melt pool size have been compared with experimental data. The temperature field development has also been monitored with localized transient reflectivity measurements.
Selective-Area Growth of Metal Oxide Films Induced by Patterned Excimer Laser Surface Photolysis
Authors: Kunz R. R. , Ehrlich D. J. , Melngailis J. , Horn M. W. 
Published: March 2011

AbstractAn excimer-laser-based method for achieving selective-area oxide growth on polymer surfaces is described. This method uses high photon energy (6.4 eV, 7.9 eV) excimer laser irradiation to change hydrophobic surfaces (surface tension <20 erg/cm2) into hydrophilic surfaces. The hydrophobic growth surfaces are prepared by exposure of a polymer to halogen-containing plasmas. Selective growth is done by simultaneously exposing patterned, laser-modified surfaces to SiC14 and H2O; the reaction takes place only where the H2O adsorbs to form a condensed adlayer. After selective growth, oxygen etching of the polymer results in the desired resist pattern. When used with a plasma-deposited carbon polymer, the result is a new all-dry lithographic process.
Diode Laser Induced Chemical Vapor Deposition of WSIx from WF6 and SiH4
Authors: Desjardins P. , Izquierdo R. , Meunier M. 
Published: March 2011

AbstractWe have developed a compact and inexpensive laser direct writing system, based on the 796 nm radiation of a 1 W diode laser array for the deposition of tungsten silicides. The laser power incident on TiN substrates varies between 50 and 550 mW. Lines are deposited from a gas mixture of WF6 and SiH4, whose total pressure is kept below 15 Torr to avoid uncontrolled reactions. Experiments are performed in a static reactor with WF6/SiH4 ratios varying from 0.2 to 10. Lines written at speeds ranging from 2 to 100 μm/s have typical thicknesses and widths varying from 30 to 1000 μm and from 4 to 15 μm respectively. Auger Electron Spectroscopy (AES) shows that no fluorine is incorporated in the WSix film, within the limit of detection. Moreover, no oxygen, carbon or nitrogen are detected in the bulk, although some surface contamination is present. From AES measurements, the W/Si ratio is estimated to be between 1.1 and 1.4 for a reactive gas mixture of WF6: SiH4 (1: 3).
Nanometer Lithography by Fast Atom or Ion Beam Milling
Authors: Devaud G. , Fleming J. , Douglas K. 
Published: March 2011

AbstractWe have produced nanometer scale patterning (nanostructures) by metal shadowing of two-dimensional protein crystals (S-layers), followed by milling with ions or fast atoms. In this parallel process, the metal overlayer is formed into a metal screen consisting of hexagonal arrays of 10 nm size holes with a 20 nm periodicity. We have studied the time evolution of the milling process, and temperature effects. Nanostructure formation may be due to preferential sputtering of the troughs relative to the crests of the metallized S-layer. The effect of temperature on pattern formation indicates that thermal diffusion is also important.
Anisotropic Si Etching by a Supersonic Cl2 Beam
Authors: Teraoka Yuden , Uesugi Fumihiko , Nishiyama Iwao 
Published: March 2011

AbstractPerpendicular etching profiles of n+-Si(100) are obtained with a supersonic Cl2 beam at substrate temperature of 900°C. Although small undercuts are observed just below the SiO2 mask, the side wall etching caused by the background Cl2 is almost negligible. An aspect ratio of greater than 6 and selectivity of greater than 8000 are obtained with 0.5 μm line & space mask pattern. From Arrhenius plots of etch rates, an effective activation energy of the nozzle beam etching is determined to 0.53 eV. Assuming that the reaction product is SiCl2, the reaction probability is estimated to be 19% at 900°C. Highly anisotropic etching of the Si(100) obtained here is due to the large reaction probability.
Thin Film Processing with Ecr and Downstream Oxygen Plasmas
Authors: Hess Dennis W. 
Published: March 2011

AbstractDownstream oxygen plasmas are used routinely to etch and strip resist materials in integrated circuit (IC) process sequences. Differences in the electrical damage incurred in thin (26 nm) silicon dioxide films on silicon due to the afterglow of rf and microwave oxygen plasmas appear to be due to higher energy VUV emission and to a greater density of positive ions in the case of rf excitation at downstream distances less than 35 cm. The high flux of oxygen ions in electron cyclotron resonance (ECR) plasmas also permits reasonable silicon oxidation rates at low temperature. Oxidation rates ofsilicon in ECR oxygen plasmas at temperatures between 250 and 450 C are comparable to those obtained for thermal oxidation in dry oxygen at temperatures above 850 C. Although oxidation rates are adequate under floating, anodic or cathodic bias conditions, only oxides grown under floating or anodic conditions display comparable chemical, physical and electrical properties to those of thermal oxides.
Ebic Investigation of Etch Induced Defects in Silicon Introduced by Rie and Ribe.
Authors: Habermeier H.-U. , Eckstein M. , Ruf C. , Jäger-Waldau G. , Zwicker G. 
Published: March 2011

AbstractSilicon single crystal wafers are lithographically patterned and etched for via holes by means of RIBE, RIE and ECR based techniques. The damage introduced by etching is analyzed using charge collection microscopy. This technique probes sensitively the occurrence of electrically active defects due to their altered electron hole recombination properties compared to the bulk material. Furthermore, investigations of the temperature dependence of the EBIC contrast give informations about the physical mechanisms for the recombination. The experiments revealed a substantial increase [several %] of the EBIC contrast in the etched part of the pattern, i.e. electrically active damage is introduced by the etching technique, giving rise to enhanced recombination. Measurements of the diffusion length in etched and unetched areas of the specimen reveal identical values, i.e. the damage is confined close to the surface. Using the different etching methods quantitatively different defect levels are found. Measurements of the temperature dependence of the EBIC contrast aimed to reveal the physical nature of the defects show a drastic increase of the contrast with decreasing temperature. This increase can be described by two regimes in an Arrhenius plot with a linear characteristic of different slopes.
The Effects of P2S5 Surface Passivation on Dry Etched GaAs
Authors: Glembocki O.J. , Dagata J.A. , Dobisz E.A. , Katzer D.S. 
Published: March 2011

AbstractThe effects of P2S5 surface passivation treatments on damage caused by chemically assisted ion beam (CAIBE) etching of GaAs have been examined using ex-situ photoreflectance. Epitaxially grown undoped GaAs on heavily doped GaAs substrates were used to determine surface electric fields. The etching process is observed to decrease surface electric fields, produce subsurface damage and to reduce surface photovoltages. Post-etching treatments with P2S5 are observed to increase surface photovoltages, but have no significant effect on the surface fields or subsurface damage. That the surface field is unaffected suggests that in etched materials the Fermi level pinning is not solely determined by the surface and that the near surface regions are important. We also find that samples pretreated with P2S5 exhibit more etch damage than those which are only degreased.
Simulations of Low-Energy Ion Bombardment and Epitaxial Growth
Authors: Chason E. , Bedrossian P. , Tsao J.Y. , Dodson B.W. , Picraux S.T. 
Published: March 2011

AbstractWe have performed computer simulations of epitaxial growth and low-energy ion bombardment for comparison with reflection high-energy electron diffraction (RHEED) mesurements. The simulations are based on a hybrid Monte Carlo/rate equation approach which includes the processes of defect creation (adatom and surface vacancy), surface diffusion, and attachment and detachment from steps and islands. In this work, we focus on simulating the experimental observations of ion-induced RHEED oscillations and cancellation of RHEED oscillations during simultaneous ion bombardment and growth. For the interaction of the low-energy ion with the surface, we consider two mechanisms: preferential sputtering (where the sputtering cross section depends on the atomic coordination) and mobile vacancies. Our results indicate that the primary interaction of the ion beam with the surface is probably through the creation of mobile vacancies, and that the degree of preferential sputtering is not large.
Low Temperature Silicon Oxidation with Electron Cyclotron Resonance Oxygen Plasma
Authors: Sung K. T. , Pang S. W. 
Published: March 2011

AbstractSilicon was oxidized at low temperature with an oxygen plasma generated by an electron cyclotron resonance (ECR) source. The ECR source utilized a multicusp magnetic field formed by permanent magnets. Microwave power at 2.45 GHz was applied to the source and rf power at 13.56 MHz was applied to the sample stage. Si oxidation was studied as a function of source distance, pressure, microwave power, and rf power. The oxide thickness increases with microwave and rf power but decreases with source distance. The oxidation rate increases with pressure up to 12 mTorr, then decreases at higher pressure. The relative emission intensities in the plasma monitored using optical emission spectroscopy showed similar dependence on the source distance and microwave power. Oxidation temperature was estimated to be <100°C. Using ellipsometry and X-ray photoelectron spectroscopy, the oxidized films were found to be close to that of thermal oxide with refractive index at 1.45 and oxygen to silicon ratio of 2. From the current-voltage and capacitance-voltage measurements, the breakdown fields of these oxide films were 6.3 MV/cm and the fixed charge densities were 7×1010 cm−2.
Low-Energy Ar+ Implantation of Uhmw-Pe Fibers: Effect on Surface Energy, Chemistry, and Adhesion Characteristics
Authors: Schalek R. , Hlavacek M. , Grummon D. S. 
Published: March 2011

AbstractUltra-high molecular weight polyethylene (UHMW-PE) has a highly chain-extended and crystalline structure which is functionally inert and requires surface-modification before it can successfully operate as a reinforcement in polymer-matrix composites. Although plasma treatments are adequate for this purpose, recent work has shown that irradiation with low-energy inert gas ions can produce increases in interfacial shear strength (ISS), in epoxy matrices, which exceed those of commercial plasma treatments, and cause little degradation in tensile properties. Low energy ions are readily produced in high-current beams using gridded sources having moderate cost, and processing times may be a short as a few seconds. In this paper, we present results of recent experiments using argon ions accelerated to energies between 100 eV and 1 keV to irradiate 20-30 µm diameter UHMW-PE fibers to doses between 1×1016 and 1×1017 cm−2, and compare our findings with previous work at higher accelerating potentials. At the optimum dose (which increases with decreasing energy), greater than 9-fold improvements in ISS level, measured in epoxy-resin droplet pulloff tests, were found for ion irradiation at 0.25 keV. Scanning electron microscopy of fiber surfaces, of ion irradiated as well as commercial oxygen plasmatreated materials, revealed small crack-like pits in both cases, with the pits smaller and more uniformly distributed on the ion-irradiated fibers. Surface chemistry studies using X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) indicate that irradiation resulted in high surface concentrations of polar functional groups, and extensive surface oxidation. This was accompanied by a substantial increase in the polar component of surface energy, which resulted in improved fiber wetting by the resin.
Characterization of the Depositing Flux in Laser Ablation Deposition (LAD).
Authors: Kools Jacques C.S. , Dieleman Jan 
Published: March 2011

AbstractAngular-resolved time-of-flight (ARTOF) studies have been performed on ablation plumes of copper generated by excimer laser fluences just above threshold in vacuum. Positive ions, Rydberg atoms and ground-state neutrals are observed. Relative concentrations, angular intensity distributions and angular- resolved velocity distributions are measured for ground state neutrals and ions.Ions have the highest kinetic energies ( 20-80 eV). Their angular distribution is isotropic. Their concentration at the substrate is very low ( ≤ 10−6). Ground state neutrals have lower energies ( ≈ 1 eV). Their intensity and velocity is a strongly decreasing function of the polar angle. Rydberg-atoms have energies in between those of ground-state neutrals and ions. Their angular distribution is also dependent on tile polar angle.The concentration, kinetic energy and angular distribution of the ionised species arc very well explained by a mechanism of thermal ionization and subsequent space-charge induced repulsion. The velocity distributions and angular intensity distributions of the ground-state neutrals are quantitatively predicted by a model for the flow dynamics of pulsed laser generated gas clouds.
The Role of Hydrogen in Laser Deposition of Diamond-Like Carbon
Authors: Thebert-Peeler D. , Murray P.T. , Petry L. , Haas T.W. 
Published: March 2011

AbstractThin films have been grown on Si (100) substrates by pulsed laser evaporation of graphite using both IR and UV radiation. The character of the resulting film is found to be independent of the presence of H°. Diamond-like films are found to be a result of low (RT) temperature deposition of the higher energy incident particles of the UV (versus IR) laser ablation process.
Uhv-Tem Studies of Laser-Induced Damage in Silicon
Authors: Savage T. S. , Xu P. , Ai R. , Dunn D. , Marks L. D. 
Published: March 2011

AbstractThe effects of pulsed laser irradiation on silicon (111) single crystal thin samples were studied in a ultra-high vacuum transmission electron microscope. Samples were found to cleave along (110) planes under the laser beam. The formation of dislocation networks was also observed. The cleaving did not seem to originate from previously observed defect areas, but from random places, and is believed to be caused by thermal shock from laser beam heating. Bulk defects in the specimens, such as stacking fault tetrahedra and dislocations, were not observed to be affected by the laser treatment.
Laser Damage Thresholds of Several Metal-Containing Acrylic Polymers at Four Different Wavelengths.
Authors: Yip Pearl W. 
Published: March 2011

AbstractSingle- and multiple-pulse laser damage thresholds of six different metal-containing acrylic polymers were determined at 10.6, 1.06, 0.53 and 0.355 μm. Light transmission of these samples before and after irradiation was measured. A variety of observed laser-materials interactions are discussed in this paper. Physical and chemical damage properties of these metal-containing acrylic polymers were examined and compared with poly (methyl methacrylate) and polycarbonate using scanning electron microscopy (SEM), infrared spectroscopy (IR), and electron spectroscopy for chemical analysis (ESCA). In general, it was found that the multiple-pulse damage thresholds were lower than the single-pulse, and damage thresholds decreased as wavelength of the testing laser beam became shorter.
Dry Etching of Copper at High Rates
Authors: Farkas Janos , Rousseau Francois , Chi Kai-Ming , Kodas Toivo T. , Hampden-Smith Mark J. 
Published: March 2011

AbstractThree new methods for dry etching of copper at temperatures below 200°C have been developed. The first relies on the formation of volatile CICu(PR3)2 species via reaction of PR3 with CuCI where R = ethyl, and butyl. The second relies on the reaction of Cu(hfac)2 and neutral ligands L such as butyne, pentyne or bistrimethylsilylacetylene to form (hfac)CuL. The last approach involves reaction of CuO with hexafluoroacetylacetone (hfacH) to form Cu(hfac)2 and water. These approaches have provided etch rates as high as 1 μm/min at 150°C.
Theoretical Aspects on Spatial Thickness Variations in Laser-Deposited Thin Films.
Authors: Singh Rajiv K. , Carignan James 
Published: March 2011

AbstractWe have studied predicted thickness uniformity of thin films deposited by the pulsed laser ablation technique. Unlike a conventional evaporation process, the spatial thickness characteristics of laser-deposited films is controlled by a number of laser and other deposition variables including laser wavelength, pulse energy density, substrate-target distance, area and shape of the laser irradiated spot, etc. The effect of these parameters on the spatial thickness variations have been analyzed by using a model proposed by Singh et. al. [1]. This model is based on the anisotropic expansion of the laser-generated high-temperature and high-pressure plasma, which is initially confined to small dimensions and then expands anisotropically in vacuum. The results show that spatial film uniformity can be improved by decreasing plasma temperature and specific heat capacity ratio of the plasma gas. For large laser irradiated spot diameters (> 8 mm), the film uniformity was found to decrease with decreasing spot diameters, but this trend reversed at smaller: irradiated spot sizes. Depending on the laser irradiated conditions and substrate-target geometry, the thickness variations have been found to vary from (cos θ)2.5 to (cos θ)12. Optimization of various parameters to decrease the spatial-thickness inhomogeneities across the film are also discussed.
Surface Laser Plasma in Laser Treatment of Materials in High Pressure Gases
Authors: Smirnov A. , Dupuy C. , Flamant G. 
Published: March 2011

AbstractUsing holographic interferometry the surface laser plasma generation in high pressure gases has been investigated. Additional information about the generation of surface cover laser plasma, optical breakdown in the presence of aerosol particles and condensation front forming in high pressure gases is given.
Excimer Laser Removal of Cr Contaminants from Polyimide Surfaces for Packaging Applications
Authors: Radhakrishnan Gouri , Marquez Nicholas , MÜller Heinrich 
Published: March 2011

AbstractExcimer laser radiation at 248 nm has been used for the maskless and selective removal of chromium (Cr) contamination from polyimide surfaces containing gold (Au) metallizations. Ablation thresholds and rates have been determined in air, vacuum, and oxygen. These results have been used to establish the optimum ablation medium and a corresponding process window that allows for selective removal of Cr from polyimide. The substantial differences between the ablated and unexposed regions of the polyimide surface have been established by electrical measurements, while the variations in their respective surface morphologies have been examined using optical and scanning electron microscopy. Quantitative determinations of Cr on the ablated and unablated regions of polyimide have been performed, using secondary ion mass spectrometry, to establish the threshold for the complete removal of Cr.
A Fast Laser Alloying Process for the Selective Electroplating of Metal on SiO2 and Polyimide
Authors: Malba Vincent , Bernhardt Anthony F. 
Published: March 2011

AbstractA new laser direct-write process for patterning of metal on multichip modules has been developed. The process involves the laser modification of the non-conductive surface of a seed multilayer, converting it to a conductive surface, which can be electroplated with metal. The seed multilayer is composed of a TiW adhesion layer, onto which a Au film is sputtered, followed by an a-Si layer, which forms the non-conductive surface. The laser modifies the surface by alloying (or mixing) the Si and Au to form the conductive surface. This laser process has been shown to be capable of writing speeds of 2.5 m/s. With a silicon dioxide interlevel dielectric layer, the process works over a large range of laser power (Pmax/Pmin ∼ 5). A polyimide interlevel dielectric layer can be used without damage or loss of adhesion, although the process margin is substantially reduced (Pmax/Pmin ∼ 2).
Computer Simulation Studies of the Temperature Dependence of Domain Growth Kinetics
Authors: Fichthorn Kristen A. , Henry Weinberg W. 
Published: March 2011

ABSTRACTUnderstanding the kinetics of domain growth in quenched systems is a significant fundamental problem with particular relevance to materials science. The temperature dependence of domain growth has interesting manifestations which lie outside current theoretical developments. In a series of Monte Carlo studies, we have investigated and obtained a detailed resolution of the temperature dependencies of domain growth in a model of a two-dimensional, quenched, chemisorbed overlayer with a nonconserved order parameter. We discuss our findings.