bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Ion Bombardment on the Nucleation and Growth of Plasna Deposited Amorphous Silicon
Authors: Antoine A. M. , Drevillon B. 
Published: March 2011

AbstractReal-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

AbstractDeep 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

AbstractUltraviolet 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

AbstractUltraviolet 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

AbstractThe 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.
The Effect of Hydrogen Ion Bombardment on Fluorocarbon Polymers
Authors: Cheeks Teresa L. , Ruoff Arthur L. 
Published: March 2011

AbstractPolytetrafluoroethylene(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

AbstractLaser 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

AbstractLaser- 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

AbstractThe 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

AbstractA 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

AbstractAℓN 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

AbstractThe 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

AbstractIn 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

AbstractA 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

AbstractPolyimides 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

AbstractHard 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

AbstractA 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

ABSTRACTReactive 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.
The Characterization of Silicon Damaged by Low Energy Argon Ion Etching
Authors: Seager C. H. , Panitz J. K. G. , Pettit R. G. , Brice D. K. 
Published: March 2011

ABSTRACTWe have used a variety of characterization techniques including electron spin resonance (ESR), photothermal deflection spectroscopy (PDS), ellipsometry, and I–V and C-V analysis to study silicon samples damaged by 500–1500 eV Ar ions from a Kaufman ion source. In agreement with our ballistic penetration calculations, PDS and ellipsometry data show that the majority of the lattice damage lies within 40Å of the surface. The ellipsometry results are well modelled as a thin, damage-induced layer of a- Si with a high (4.63) refractive index, while the PDS measurements show an Urbach-like subgap adsorptance tail. In addition to Schottky barrier height alterations produced by Ar bombardment, we also observe marked changes in electrically active dopant densities in boron doped silicon samples. C-V analyses show that these changes extend quite far (1–2 μm) into the sample and are readily removed by a mild (150°C) thermal anneal. Hydrogen, injected from surface adsorbed H2O or hydrocarbons, appears to be the source of these effects. We will also discuss our upper limit estimate of 1013 “dangling bond” spins/cm2 for our damaged samples in light of prior ESR observations on similarly treated surfaces.
The Role of F Atoms in the Reactive Sputter Etching of Silicon Dioxide: Langmuir Probe and Optical Actinometry Measurements
Authors: Steinbrüchel C H. , Curtis B. J. 
Published: March 2011

ABSTRACTReactive sputter etching of SiO2 in a low-pressure CF4 -O2 plasma has been investigated using a Langmuir probe to determine ion fluxes to the substrate and optical actinometry to monitor the concentration of F atoms, [F]. Etch yields Y, i.e. the number of substrate atoms removed per impinging ion, are obtained vs O2 composition and vs pressure. At constant pressure Y decreases slightly, but [F] increases considerably, with increasing O2 content. On the other hand, at constant O2 composition both Y and [F] increase strongly with increasing pressure. These results suggest that at low [F], relative to the ion flux to the substrate, the dominant etch mechanism is direct reactive ion etching, with the ions themselves as the main reactants, whereas at high [F] the overall etching is ion-enhanced, with F atoms as the main neutral reactants.
Surface Characteristics of Monocrystalline ß-SiC dry etched in fluorinated gases
Authors: Palmour John W. , Davis R. F. , Astell-Burt P. , Blackborow P. 
Published: March 2011

ABSTRACTMonocrystalline ß-SiC (100) thin films were dry etched in CF4 and NF3 by reactive ion etching (RIE) and in SF6 by plasma etching. The etched surfaces were characterized by Auger Electron Spectroscopy (AES) and Scanning Electron Microscopy (SEM). The use of a stainless steel or an anodized Al cathode during RIE created a roughened SiC surface, which was contaminated with Fe or Al2 O3respectively. The roughness was caused by a micromasking effect produced by the deposition of these contaminants. By contrast, a carbon cathode yielded a very smooth and a much cleaner etched surface. Plasma etching of SiC in SF6 resulted in a very rough surface, but the AES spectra indicated almost no contamination and very little native oxide or fluorine. The optimal condition for etching SiC was determined to be RIE in NF 3 on a C cathode.
Laser Microfabrication Technology and its Application to High Speed Interconnect of Gate Arrays
Authors: Bernhardt Anthony F. , McWilliams Bruce M. , Mitlitsky Fred , Whitehead John C. 
Published: March 2011

ABSTRACTNickel and doped polysilicon lines can be written at speeds exceeding 1000 microns/sec using laser direct-write deposition. We explore the roles of gas pressure, composition, and laser power in determining writing speed and line morphology. The use of a surface layer of amorphous silicon provides optical absorption, thermal and electrical insulation which help to maintain high, relatively stable, surface temperature.Laser direct-write deposition is used to interconnect CMOS gate arrays by means of computer controlled laser pantography. Complex circuits, such as an array of five 16-stage shift registers and one 16-stage counter have been successfully fabricated and tested.
A Silicon Field Emitter Array Planar Vacuum FET Fabricated with Microfabrication Techniques
Authors: Gray Henry F. , Campisi G. J. 
Published: March 2011

ABSTRACTIn this paper we will discuss a new type of field effect transistor, a vacuum FET, where the usual channel material is the vacuum rather than a semiconductor. This new device is based on Field Emitter Arrays (FEA) which are inherently submicron structures. That is, the field emitters themselves must have dimensions less that 0.1 micrometers in order to generate the high electrostatic fields necessary for electron tunneling, and the control gate (or extraction electrode) must be very close to the field emitter tip in order to generate these high fields with reasonable voltages. Consequently, this new “FET” is the first of a new class of vaccum electronic switching devices based on microfabrication techniques, and susceptible to circuit integration.