bluuebunny/crossref_metadata_2025_split huggingface dataset:
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 if 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, men 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.
Characterization of High Temperature Superconducting Thin Film Grown by Laser Ablation Method
Authors: Shimizu K. , Nobumasa H. , Nagai N. , Matsunobe T. , Kawai T. 
Published: March 2011

ABSTRACTWe have measured the complex dielectric function of BizSr2Ca1Cu2Ox samples in the near infrared region directly by spectroellipsometry. As for both single crystal and thin film, superconducting samples have a zero point in the real part (ε1) of the complex dielectric function (ε*) and a clear peak of the imaginary part of the inverse ε* at almost the same frequency. On the other hand, non-superconducting samples have no such ei zero point, and the peak height of (-Im(1/ε*)) becomes small. Then we can determine the superconductivity of samples by this spectroellipsometry measurement at room temperature.
In SituCharacterization of the Pulsed Laser Deposition of Magnetic Thin Films
Authors: Paul A. J. , Bonnell D. W. , Hastie J. W. , Schenck P. K. , Shull R. D. , Ritter J. J. 
Published: March 2011

ABSTRACTPulsed Laser Deposition (PLD) has been proven as an effective means of depositing films from refractory targets. In our earlier work, either Nd/YAG or excimer lasers, interacting directly with target surfaces, were used to deposit thin films of high Tcsuperconductors, high dielectric constant BaTiO3and ferroelectric PbZr0.53Ti0.47Os3(PZT). Time-resolved molecular beam mass spectrometry and optical emission spectroscopic techniques have been developed to characterize the vapor plumes responsible for film formation. More recently, this work has been extended to the PLD of magnetic thin films of Ag-Fe3O4nanocomposites using excimer (ArF*, 193 nm) laser excitation. Optical emission spectra of the excited vapor phase species, formed during the plume generation and material deposition process, indicate that physically compressed powdered metal targets have inadequate homogeneity for film production, compared to targets that are chemically produced. Anin situLaser-induced Vaporization Mass Spectrometry (LVMS) technique utilizing a Nd/YAG (1064 nm) laser has been used to determine Time-of-Arrival (TOA) profiles of the atomic, molecular, and ionic species produced in the plumes of Ag-Fe3O4The neutral species TOA profiles indicate velocity distributions that are multimodal and not Maxwellian. These observations are in contrast to the TOA profiles observed from one-component targets (Ag or Fe3O4), where a single Maxwellian velocity distribution is found. Mossbauer effect measurements of the thin films have been made for correlation with the gas phase studies.
Photophysics of Polyatomic Species Ejection Following UV Laser Ablation of Single Crystal Bi2Sr2Ca1Cu2O8
Authors: Wiedeman Lawrence , Kim Hyun-Sook , Helvajian Henry 
Published: March 2011

ABSTRACTA series of experiments have been conducted which probe the origin of the polyatomic ions (e.g., Sr2O+, BiCu+) measured following the low fluence, pulsed UV laser irradiation of crystalline Bi2Sr2CaCu2O8 (BiSrCaCuO). The photoejection of polyatomic species presents a problem for the pulsed laser deposition (PLD) technique. The deposition of polyatomic products could limit epitaxial growth during thin film material processing. Our results indicate that the polyatomic species are not the consequence of a gas phase recombination, but are in fact directly produced. All experiments are done at laser fluences below that required for above surface plasma formation. As such, our results do not address the formation of large clusters within the dense plume in high fluence laser ablation.
Surface Studies of Laser Processing of W on GaAs from WF6
Authors: Tabbal M. , Lecours A. , Izquierdo R. , Meunier M. , Yelon A. 
Published: March 2011

AbstractLaser Chemical Vapor Deposition of tungsten on GaAs from WF6 using a focused cw scanning argon-ion laser beam has been investigated. Lines have been produced using different mixtures of WF6:H2 and WF6:SiH4 and in some cases, without any reducing gas. Depositions are found to occur within a narrow process window, and are difficult to reproduce. In order to understand this process, we have performed surface analysis on GaAs samples exposed to WF6. X-Ray Photoelectron Spectroscopy studies on the interaction between WF6 and GaAs in the absence of laser illumination show that fluorinated tungsten compounds are present on the GaAs surface. Furthermore, the existence of a chemical reaction leading to the formation of GaF3 at the surface and to a loss of the stoichiometry of the substrate surface is detected. Possible mechanisms, and the effects of these reactions on the deposition process are discussed.
Enhancement of Photoresist Etch Rates by Argon Metastables in a Plasma Afterglow Reactor
Authors: Koretsky Milo D. , Reimer Jeffrey A. 
Published: March 2011

AbstractThe etching of a novolak-based positive photoresist was studied downstream of O2/CF4 and Ar/O2/CF4 plasmas. Gas phase electron resonance was used to quantitatively track the two primary etchant species, atomic oxygen and atomic fluorine. These species were then correlated to etch rates as determined by laser interferometry. In addition to being industrially relevant, the downstream reactor allows the influence of neutral chemistry and surface activation to be deconvoluted from that of ion bombardment and strong electric fields, which traditionally make processes occurring in the body of the plasma so difficult to understand. The maximum in etch rate with respect to CF4 addition to an oxygen plasma yields an optimum ratio of O/F of 20 at 150 °C. The addition of argon to the O2/CF4 gas mixture unexpectedly leads to an increase in etch rate by a factor of at least two. Moreover, the optimum O/F ratio decreases by a factor of three and, correspondingly, the optimum CF4 mole fraction decieases. Analysis of oxygen and fluorine densities suggests argon metastables alter the homogeneous chemistry for fluorine atom production as well as the heterogeneous chemistry of photoresist chain scission. Overall activation energies are 10.6, 10.8, 4.1 and 0.7 kcal/mole for O2, Ar/O2, O2/CF4 and Ar/O2/CF4 mixtures, respectively. The optimal CF4 mole fraction increases with increasing substrate temperature. A Hougen-Watson model for the heterogeneous chemistry on the wafer surface reproduces the data very well.
Evaluation of Semiconductor Lattice Damage Using a Newly-Developed Photodisplacement Laser Probe
Authors: Sumie S. , Takamatsu H. , Tsunaki H. , Nishimoto Y. , Nakai Y 
Published: March 2011

AbstractA highly sensitive laser probe for photo-acoustic displacement(PAD) has been developed and applied to the monitoring of low-level lattice damage in semiconductors. Since a photodisplacement laser probe with the sensitivity of 0.1 picometers is employed in this measurement, lower density damage for instance, formed by 50 keV B+ implantation with a dose of 5X109 ions/cm2 can be detected. Correlation of the PAD with damage density was obtained in B+ implantation. Therefore, quantitative damage density can be obtained from the relation for lightly damaged layers, such as formed by chemomechanical polishing and by electron cyclotron resonance plasma etching. This technique is useful-for monitoring of low damage density surface.
Ion Beam Etching System for Mercury Cadmium Telluride and III-V Compound Semiconductors
Authors: Reeves Geoffrey K. , Leech Patrick. W. , Bond Patrick 
Published: March 2011

AbstractThis paper describes a laboratory built ion beam etching system and its performance when used for etching Hg1-xCdxTe, GaAs and InP. The etching system provides a means for forming device mesas on a wide range of semiconductors without having to resort to wet chemical etches. The system uses a Kaufmann ion source, a rotating platform and two flow controllers to allow the variation of gas ratios and flows.
Laser-Induced Desorption of in and Ga from Si(100) and Adsorbate Enhanced Surface Damage
Authors: Strupp Paul G. , Alstrin April L. , Korte Brenda J. , Leone Stephen R. 
Published: March 2011

AbstractLaser-induced desorption (LID) of In and Ga from Si(100) under ultra-high vacuum conditions is investigated. The frequency doubled 532 nm, 2-6 ns output of a Nd:YAG laser is focussed to 0. 14±0.03 J/cm2 on the Si surface to induce desorption. Desorbed In or Ga atoms are detected by laser-induced fluorescence initiated by a pulsed dye laser propagating in front of the surface. LID occurs by thermal desorption with approximate desorption energies and pre-exponential factors in agreement with literature values from previous isothermal desorption measurements. Experiments at higher coverages suggest that desorption occurs predominantly from the two-dimensional (2D) adsorbate layer with little desorption occurring directly from adsorbate islands. The 2D layer is resupplied by either diffusion out of adsorbate islands or by diffusion of incorporated adsorbate out of the bulk. Adsorbate-enhanced laser-induced surface damage is also observed; only 0.2 monolayer of In reduces the number of laser pulses required to observe damage by greater than a factor of 30.
Epitaxy and Chemical Reactions During Thin Film Formation from Low Energy Ions New Kinetic Pathways, New Phases and New Properties
Authors: Herbots Nicole , Hellman O.C. , Vancauwenberghe O. 
Published: March 2011

AbstractThree important effects of low energy direct Ion Beam Deposition (IBD) are the athermal incorporation of material into a substrate, the enhancement of atomic mobility in the subsurface, and the modification of growth kinetics it creates. All lead to a significant lowering of the temperature necessary to induce epitaxial growth and chemical reactions. The fundamental understanding and new applications of low temperature kinetics induced by low energy ions in thin film growth and surface processing of semiconductors are reviewed. It is shown that the mechanism of IBD growth can be understood and computed quantitatively using a simple model including ion induced defect generation and sputtering, elastic recombination, thermal diffusion, chemical reactivity, and desorption The energy, temperature and dose dependence of growth rate, epitaxy, and chemical reaction during IBD is found to be controlled by the net recombination rate of interstitials at the surface in the case of epitaxy and unreacted films, and by the balance between ion beam decomposition and phase formation induced by ion beam generated defects in the case of compound thin films. Recent systematic experiments on the formation of oxides and nitrides on Si, Ge/Si(100), heteroepitaxial SixGe1−x/Si(100) and GaAs(100) illustrate applications of this mechanism using IBD in the form of Ion Beam Nitridation (IBN), Ion Beam Oxidation (IBO) and Combined Ion and Molecular beam Deposition (CIMD). It is shown that these techniques enable (1) the formation of conventional phases in conditions never used before, (2) the control and creation of properties via new degrees of freedom such as ion energy and lowered substrate temperatures, and (3) the formation of new metastable heterostructures that cannot be grown by pure thermal means.
Atomic Oxygen Plasma Effects on Cvd Deposited Diamond-Like Carbon Films
Authors: Hale Jeffrey S. , Synowicki R.A. , Nafis S. , Woollam John A. 
Published: March 2011

AbstractCVD deposited diamond-like carbon (DLC) films have been studied for possible use as a secondary standard for Low Earth Orbit materials degradation. Samples of various thicknesses have been exposed to a simulated Low Earth Orbit atomic oxygen (AO) environment using a plasma asher. Mass loss measurements indicate that DLC degrades at a rate of 0.7 mg/hr which is two to three times the rate of currently used Kapton samples which degrade at a rate of.3 mg/hr. Thickness measurements show that DLC thins at a rate of 77 Angstroms/min. Since DLC is not as susceptible to environmental factors such as moisture absorption, it could potentially provide more accurate measurements of AO fluence on short space flights. Adhesion of DLC films to both fused silica and crystalline silicon substrates has been studied under thermal cycling conditions. Film adhesion to fused silica can be enhanced by sputtering a thin layer of silicon dioxide onto the substrate prior to deposition. In addition to the above, the index of refraction and extinction coefficient of various thicknesses of DLC films has been characterized by Variable Angle Spectroscopic Ellipsometry.
Growth and High Resolution Tem Characterization of GexSi1−x/Si Hetero-Structures by Remote Plasma-Enhanced Chemical Vapor Deposition
Authors: Qian R. , Chung I. , Kinosky D. , Hsu T. , Irby J. , Mahajan A. , Thomas S. , Banerjee S. , Tasch A. 
Published: March 2011

AbstractRemote Plasma-enhanced Chemical Vapor Deposition (RPCVD) has been used to grow GexSi1−x/Si heteroepitaxial thin films at low temperatures (∼450°C). In situ RHEED has been used to confirm that smooth, single crystal heteroepitaxial films can be grown by RPCVD. Plan-view and cross-sectional TEM have been employed to study the microstructure of the heteroepitaxial films. Lattice imaging high resolution TEM (HRTEM) has shown perfect epitaxial lattice alignment at the heterojunction interfaces. GexSi1−x/Si films which exceed their CLT's appreciably show dense Moiré fringes under plan-view TEM. The spacings between the fringes have been used to estimate the relaxed lattice constants. In addition to the inhomogeneous strain observed in XTEM, Selected Area electron Diffraction (SAD) analysis of the interfaces displays two split patterns. The spacings between the diffraction spots have been used to calculate the lattice constants in the epitaxial films in different crystal directions, which agree very well with the prediction by Vegard's law as well as the estimate from planview TEM analysis. HRTEM analysis also reveals the crystallographic nature of the interfacial misfit dislocations in the relaxed films.
Pulsed Laser Planarization of Metals for IC Interconnect
Authors: Baseman Robert J. , Kuan Tung-Sheng , Aboelfotoh M. Osama , Andreshak Joseph C. , Turene Frank E. , Previti-Kelly Rosemary A. , Ryan James G. 
Published: March 2011

AbstractWe consider the feasibility of using an excimer laser to planarize copper deposited over polyimide. Even though the polyimide is thermally sensitive, a 2.8 µn thick copper film, deposited over polyimide, was planarized with 248 nm, 25 ns, laser fluences from 1.7 to 2.6 J/cm2. Although planar surfaces were readily produced, a variety of defects were observed in the underlying structures. The defects observed include stress induced fractures of the interconnect structure, polyimide surface roughening, and changes in the electrical characteristics of the polyimide. We also describe cross sectional TEM images of cavities formed in interlayer contacts during laser planarization that support recent descriptions of the surface tension driven flow.
Excimer Laser Induced Modification of Teflon Surface into Silicon Carbide-Like
Authors: Okoshi M. , Toyoda K. , Murahara M. 
Published: March 2011

AbstractA silicon carbide-like layer was produced in the near-surface region of teflon by irradiating with an ArF excimer laser in a SiH4 and B(CH3)3 mixed gas atmosphere. The pure photochemical reaction was employed in the modification process, and the defluorination of the surface was performed with boron atoms which were photodissociated from B(CH3)3. The CH3 radicals, also photodissociated, induced the dehydrogenation of SiH4 gas; which followed the production of SiHx radicals. The SiHx radicals and CH3 radicals which could not have induced the dehydrogenation of SiH4 were substituted for fluorine atoms of the surface. As a result, the surface was photomodified into silicon carbide. Chemical composition of the photomodified surface was inspected by the XPS and the ATR-FT-IR spectra measurement, and the bonding of the Si-CH3 radicals which traded off the reduction of the fluorine atoms was comfirmed. The Si/C composition ratio of the photomodified surface was 0.7.
Excimer Laser-Induced Decomposition of Aluminum Nitride
Authors: Esrom H. , Zhang J-Y , Pedraza A.J. 
Published: March 2011

AbstractA thin film of aluminum, detected by x-ray photoelectron spectroscopy, is left at the surface of aluminum nitride (AIN) substrates exposed to a high intensity excimer laser beam of UV radiation. Due to the presence of this film, there is a decrease in the surface resistivity of the substrate with increasing number of laser pulses. In addition, line profilometry shows a decrease of the surface roughness with the number of pulses.The thermal decomposition of AIN is assumed to take place in two stages. In the first, liquid aluminum is produced together with the evolution of gaseous nitrogen, and in the second, aluminum evaporates. Using a computer model to simulate the laser heating cycle, it is shown that the thickness of the aluminum film saturates at a given laser energy density. The saturation thickness is a strong function of the substrate absorption and reflectivity and, therefore, of the laser light frequency. The influence of the substrate roughness on the electrical resistivity of the aluminum film is discussed.The application of this process to direct laser writing in high density hybrid circuits is illustrated. During hole drilling by excimer laser, a thin aluminum film is continuously produced at the hole walls. This process can also be employed for substrate planarization.
Dynamics of Graphite Photoablation
Authors: Murray P. T. , Peeler D.T. , Dempsey D. V. 
Published: March 2011

AbstractSpeed distributions were determined for the ions, ground state and electronicallyexcited neutrals ejected from a graphite target by 248 nm laser ablation. Mass distributions were measured for the laser-ejected ions. The measurements were carried out normal to the graphite target as well as at an angle of 45°. Significant differences were observed in both the speed and mass distributions at the two angles.
Effects of Processing Parameters on KrF Excimer Laser Ablation Deposited ZrO2 Films
Authors: Smith Gary A. , Chen Li-Chyong , Chuang Mei-Chen 
Published: March 2011

AbstractSystematic experiments have been carried out to characterize the yttria containing zirconia thin films on sapphire substrates by 248nm KrF excimer laser ablation. The deposition rate as a function of laser fluence and O2 pressure at room temperature was measured with a quartz crystal microbalance. The results show different threshold fluences for deposition in vacuum vs. oxygen. While the deposition rate increases with increasing fluence at a given oxygen pressure, the rate eventually saturates at a higher laser fluence. At a given fluence, the oxygen pressure dependence of the deposition rate shows a radical reduction when the O2 pressure increases from 10 mTorr to 1 Torr. Rutherford backscattering spectrometry (RBS) and x-ray photoelectron spectroscopy were used to obtain stoichiometric information. A very strong pressure dependence of the O/Zr ratio was observed. While the trend of increasing O/Zr and Zr/Y ratio with increasing O2 pressure is apparent, the correlations between O/Zr as well as Zr/Y ratio and other processing conditions are less obvious. RBS results indicate an increasing roughness at the interface between the ZrO2 film and the sapphire substrate as the oxygen pressure exceeds 50 mTorr. The structural information obtained from x-ray diffraction patterns indicates broadening of peak width with increasing laser fluence as well as decreasing substrate temperature. For the film deposited at a lower substrate temperature, a strong (002) texture was observed.
Processing of Y1Ba2Cu3O7-x Superconducting Thin Films on GaAs Substrates with Double Buffer Layers
Authors: Lee Sang Yeol , Jia Quanxi , Anderson Wayne A. , Shaw David T. 
Published: March 2011

AbstractHigh temperature superconducting Y1Ba2Cu3O7-x(YBCO) thin films have been grown on GaAs substrates by in situ laser deposition with a double buffer layer of yttrium-stabilized ZrO2 (YSZ)/Si3N4. A barrier layer using a combination of YSZ/Si3N4 was used to grow high quality YBCO thin films without the degradation of the GaAs during YBCO film deposition. Strongly c-axis oriented superconducting YBCO thin films with a zero resistance temperature of 85.5 K and a critical current density of 1.9x103 A/cm2 at 77 K have been obtained. The electrical properties of the YBCO thin films were mainly dependent on YSZ buffer layer deposition condition.
Ambient Gas Effects on Debris Formed During KrF Laser Ablation of Polyimide
Authors: Küper Stephan , Brannon James 
Published: March 2011

AbstractThe surface debris that results from KrF excimer laser ablation of polyimide has been investigated as a function of the pressure. and atomic or molecular weight of several ambient gases: H2, He. Ne, air, Ar, Kr, and Xe. A linear relation between the measured debris radius and the inverse third root of the ambient pressure was found to exist, consistent with the predictions of blast wave theory. No measureable debris could be observed using helium or hydrogen gases up to 1 atm. similar to previous reports on helium. The derived value of the blast energy. equal to about 5% of the incident pulse energy, was used to estimate a nascent blast pressure of approximately 150 atm. By making the assumption that surface debris will form if the ablation fragments are confined in a “small” volume for a “sufficient” time, then conclusions from blast wave theory suggest how to decrease the amount of generated debris.
Photoinduced Selective Deposition of Aluminium Thin Film Using Dimethylaluminum Hydride
Authors: Hanabusa Mitsugu , Ouchi Hideki , Ishida Kenji , Kawasaki Masahiro , Shogen Satoshi 
Published: March 2011

AbstractAluminum thin film was deposited via a photochemical surface reaction of dimethylaluminum hydride (DMAH) using a deuterium lamp. The period required to initiate the film growth differed with substrate, and making use of this result the film could be grown preferentially on silicon nitride and silicon oxide layers rather than on wet-etched silicon. On the basis of an x-ray photoelectron spectroscopy the observed dependence of photodeposition on substrate surfaces can be attributed to how DMAH is chemisorbed initially.