bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma Deposition of Wide Gap, Highly Photoconductive a-Si:H Thin Films from Disilane-Helium Mixtures
Authors: Rajeswaran G. , Vanier P. E. , Corderman R. R. , Kampas F. J. 
Published: April 2011

AbstractWide gap (>1.9 eV), photoconductive, intrinsic amorphous silicon films were made in a UHV system from Si2H6 -He mixtures. The hydrogen concentrations, optical gaps and photoconductivities were measured. Unlike films made from SiH4, Si2H6-produced films exhibit excellent electronic properties even at low deposition temperatures. The ratio of AM1 photoconductivity to dark conductivity was as high as 107.
Modeling Thermal Plasma Material Processing Experiments
Authors: Varacalle D. J. , Richardson L. S. , Mc Ilwain M. E. 
Published: April 2011

ArstractSpatial distributions of plasma variables (concentration, temperature, and velocity) were calculated for alumina and carbon species injected in an argon thermal plasma. The plasma behavior was modeled from arc initiation through free plume expansion by combining a plasma code with a plume code. The model assumed a direct current, constrictor type, arc heater. This research, supported by the U.S. Bureau of Mines under the Strategic and Critical Materials Program, is examining the feasibility of using thermal plasmas for ore reduction. The process investigated in this paper is the carbothermic reduction of alumina.
Plasma Enhancement in Direct Nitridation of Silicon and Silicon-Dioxide
Authors: Ito T. , Kato I. , Ishikawa H. 
Published: April 2011

AbstractEffects of plasma on direct nitridation of Si and SiO2 have been investigated. The reactor consisted of a quartz tube, SiC-coated carbon-susceptors and an RF-induction coil. The electrical probe technique was used to detect floating potential of the susceptor having Si substrates. The voltage distribution between the susceptor and plasma is influenced by nitridation ambient, pressure, reactor geometry and RF power. The predominant species in NH3 plasma is NH radicals which are thought to be negatively charged in an ion sheath formed around the susceptor. The Cabrera-Mott model has been successfully applied to analyze the nitridation mechanism. Plasma enhancement is mainly caused by activation of characteristic velocity of nitridation species rather than by an increase in the electric field appearing in a film. Enhancement due to fluorine incorporation is also explained with the model. Bombardment of ionic species causes sputtering and deposition resulting in damage, contamination and thickness nonuniformity. Optimizing the plasma conditions, decrease in nitridation temperature, increase in growth rate, and improvements in film composition and interfacial structure have been obtained. It has been found that the further nitridation proceeds, the lower Nss becomes. This technique offers various advantages to the VLSI dielectric process.
Studies of Plasma O Atom Concentration by Two-Photon Laser Induced Fluorescence and Optical Emission Spectroscopy
Authors: Walkup R. , Saenger K. , Selwyn G. S. 
Published: April 2011

AbstractWe report quantitative measurements of the concentration of atomic oxygen in RF plasmas determined by two-photon laser induced fluorescence. The results are compared with concurrent measurements of spatially resolved plasma induced optical emission. These measurements establish: (1) the O atom concentration as a function of plasma parameters, (2) a semi-quantitative relationship between O* emission intensity normalized by Ar* in-tensity and O atom concentration, and (3) an understanding of the mechanisms for pro-duction of excited atoms in the plasma.
Laser Diagnostics of Semiconductor Processing Systems
Authors: Wormhoudt Joda C. , Stanton Alan C. , Silver Joel A. 
Published: April 2011

AbstractTwo processes of great importance in the semiconductor industry are vapor deposition and plasma etching. This paper presents a review of laser techniques for spectroscopic characterization of the gas phase species involved in these processes. Band strength and other spectroscopic data for selected molecules are used to give estimates of the detection sensitivity in vibrational and electronic bands. Preliminary results are given from work presently in progress in our laboratory on the detection of such species. The discussion includes examples of the application of these techniques to a number of laboratory deposition and etching devices.
Scanning Tunneling Spectroscopy of Photoexcitations on a Nanosecond Time-Scale
Authors: Ruskell Todd G. , Chen Dong , Sarid Dror 
Published: April 2011

ABSTRACTScanning tunneling spectroscopy of the high frequency response of photoexcited carriers in the layered structure semiconductors n–type MoS2 and p–type Wse2 is demonstrated using the beat frequency of the longitudinal modes of a HeNe laser at the tunneling junction. We analyze the optical response taking into account the effects of tip-induced band bending and surface states.
Does 0.1 Micron = MACH 1?
Authors: Pease R. Fabian 
Published: April 2011

ABSTRACTThe drive to increasingly higher density ultra-large-scale-integration (ULSI) (of electronic circuits) is fuelled primarily by cost; on-chip interconnects are far cheaper than the less dense offchip interconnects. At the same time the escalating cost of an IC factory (‘fab’) is making headlines as it goes through $1B and a large part of this escalation is the cost of high performance lithography tools. The lithographic technology to go below 0.1μm will almost certainly be very different from an extension of today's optical projection and the cost of replacing today's technology will be enormous. A second drawback to higher density is the resistance of narrow interconnects. As a result some people have suggested that this situation is analogous to that of airliner speed which increased over a period of thirty years from about 100 mph to close to 600 mph but has not increased in the last 35 years. Still faster speed was technically possible, and hence was pursued by the military, but is uneconomical for most commercial use. Current technology might take us to 0.1μm which will probably be state of the art 10 years hence so technologies for replacing optical lithography e.g. scanned arrays of proximal probes should be researched now. Other challenges include how to achieve useful interconnect networks employing 50 nm features.
Self-Assembled Monolayer Films for Nanofabrication
Authors: Dobisz Elizabeth A. , Perkins F. Keith , Brandow Susan L. , Calvert Jeffrey M. , Marrian Christie R.K. 
Published: April 2011

ABSTRACTCentral to nanofabrication is the ability to transfer a pattern from an imaging layer to a device or structure. At the smallest dimensions (<20 nm), thin resists or imaging layers have been used exclusively. The transfer of a pattern that is formed in a thin layer resist presents severe technological challenges to resist materials development. A novel approach based on self-assembling monomolecular layer resists is demonstrated with two organosilane films, formed from (aminoethylaminomethyl)phenethyltrimethoxysilane (PEDA) and 4-chloromethylphenyltrichlorosilane (CMPTS). The molecules have separate chemical functionalities for binding to a Si substrate and for promoting chemistry leading to catalysis and the growth of an electroless plated metal film. STM lithographic exposure destroys the ability of the molecule to bind to a catalyst, which initiates an electroless metallization. This forms the basis for a selective imaging and the pattern transfer process. A 25 nm thick Ni layer acts as a very robust etch mask, even as the unmasked regions of Si are etched as deep as 5 μm by reactive ion etching with SF6. With our process 15 nm lines with 3.3 nm edge roughness have been fabricated in the plated Ni and etched into the underlying Si. The development of the resist process and the STM lithography will be described and the resolution of the approach will be discussed.
Nanoscale Structures by Laser Direct Writing in Silicon
Authors: Dirac H. , Müllenborn M. , Petersen J. W. 
Published: April 2011

ABSTRACTLaser-induced pyrolytic etching of silicon by chlorine has been used to process structures with nanoscale resolution. A direct write system has been designed, based on an Ar ion laser with a UV-option, on-axis optics, acousto-optic beam modulation, and high resolution translation stages for sample displacement and for focusing.The resolution of the process is determined by the size of the melt generated by the focused laser beam. The melt size is a function of optical power, and resolutions better than the focused laser spot diameter are achieved by reducing the power onto the silicon sample. In this way we have etched trenches with a resolution better than 150 nm. We demonstrate feature sizes of about 40 nm by closely spacing etched trenches. The minimum width of these features is determined by the etch selectivity. The feature width depends on the trench geometry, line spacing, and on scan speed, due to heat flow confinement.
Nanolithography Developed Through Electron Beam Induced Surface Reaction
Authors: Matsui S. , Ochiai Y. , Baba M. , Fujita J. , Watanabe H. , Manako S. , Ohnishi Y. , Ogai K. , Kimura Y. , Shimizu R. 
Published: April 2011

ABSTRACTNanolithography has been studied by using electron beam technology. Ten-nm linewidth PMMA resist patterns have been demonstrated by 50 kV scanning electron beam. The self-developing properties of a AlF3 doped LiF inorganic resist under a scanning electron beam irradiation with energy of 20–50 keV have been studied for sub-10 nm lithography. By optimizing the inorganic resist film quality, 5 nm linewidth patterns with 60 nm periodicity were directly delineated under a 30 keV electron beam. Another approach for nanolithography using electron beam holography has been proposed. Line and dot patterns with 100 nm periodicity were exposed on PMMA resist by electron beam holography with thermal field emitter gun and an electron biprism. Subsequent atomic force microscope observation has confirmed that both patterns are successfully fabricated. This technique allows us to produce nanoscale periodic patterns simultaneously. The selective atomic desorption of Cl atoms adsorbed on a Si (111) 7×7 surface has been studied by field evaporation using a scanning tunneling microscope (STM). The STM tip is placed on the adsorbed Cl on the surface, and pulse voltage was applied. This results in selective atomic desorption of Cl.
Manufacture of Submicron Light-Emitting Porous Silicon Areas for Miniature LEDs
Authors: Duttagupta S. P. , Peng C. , Tsybeskov L. , Fauchet P. M. 
Published: April 2011

ABSTRACTWe have investigated several methods to form submicron-size porous silicon regions. Porous silicon can emit light from the violet to past 1.5 μm with high photoluminescence efficiency at room temperature. It is composed of a high density of nanometer-scale crystalline silicon wires or dots. To integrate light-emitting porous silicon (LEPSi) LEDs with conventional Si microelectronics, it is necessary to produce miniature LEPSi regions adjacent to fully protected crystalline silicon regions. These techniques can be divided into two groups. In the first group formation of LEPSi is prevented during electrochemistry. Using optical and electron beam lithography, and a trilayer process with silicon nitride or amorphization by ion-implantation, we have made LEPSi patterns as small as 100 nm. In the second group, the formation of LEPSi during electrochemistry is enhanced by ion-milling or reactive ion-etching which we have found to help the pore nucleation. We have used a variety of mapping techniques, such as photoluminescence, atomic force and electron beam microscopies, to characterize the sharpness of the interface between the porous silicon and crystalline silicon regions.
Microstructure of Agglomerates of Nanometer Particles
Authors: Weber Alfred P. , Thorne James D. , Friedlander Sheldon K. 
Published: April 2011

ABSTRACTThe microstructure of an agglomerate can be characterized by the coordination number. The relationship between the fractal dimension and the coordination number of agglomerates of nanometer particles was investigated in experiments and computer simulations. The results for silver agglomerates formed by laser ablation agreed well with the simulations. The coordination number is low for low density fractals because of the large fraction of surface particles which have fewer bonds. The sensitivity of the coordination number to the fractal dimension increases with increasing fractal dimension.
Dielectric Properties Of Low Dielectric Constant Polymeric Materials
Authors: Ip Flora S. , Ting Chiu 
Published: April 2011

AbstractMultilevel interconnects for high performance ULSI need low dielectric constant materials for inter-metal layer dielectric, or ILD, to reduce signal propagation delay, power consumption and cross talk noises. We have studied the physical, dielectric and processing properties of a wide variety of promising low dielectric polymeric materials for ILD applications. This paper presents capacitance values measured over a wide range of temperature, and a summary of the measured dielectric properties. The anisotropy 1,2 of dielectric properties were determined experimentally, the vertical (out-of-plane) dielectric properties were determined by MIM (Metal-Insulator-Metal) measurements, and the horizontal (in-plane) dielectric properties were determined by intra-line measurements of sub-half micron serpentine and comb test structures.
Glass Transition Temperature Of Ultrathin Polymer Films On Silicon
Authors: Wu Wen-Li , Wallace William E , Zanten John Van 
Published: April 2011

AbstractThe glass transition temperature, Tg, of polystyrene (PS) thin films on silicon wafers with different surface preparations was determined in order to explore the effect of interfacial interaction energy on local chain dynamics. To enhance interface behavior, the film thickness included in this work was as low as 50 Å. PS with monodisperse molecular weights was chosen as a model polymer. Two different silicon surfaces were prepared: sulfuric acid-clean and hydrogen passivated. Tg of thin films was determined by monitoring the film thickness as a function of temperature. Tgwas identified as the temperature where the thermal expansion coefficient underwent an abrupt change. X-ray reflectivity was used to determine film thickness with a precision of a few angstroms. Tg of PS was found to depend strongly on the initial film thickness, as well as the substrate surface.
Preparation And Properties Of Fluorinated Amorphous Carbon Thin Films By Plasma Enhanced Chemical Vapor Deposition
Authors: Endo Kazuhiko , Tatsumi Toru 
Published: April 2011

AbstractFluorinated amorphous carbon films are proposed as low dielectric constant interlayer dielectrics for ULSI circuits. The films are deposited by plasma enhanced chemical vapor deposition with CH4, CF4 and C2F6 in a parallel-plate rf (13.56 MHz) reactor and a helicon wave reactor. In a parallel-plate reactor, the dielectric constant of the amorphous carbon films deposited with CH4 increases with increase in rf power. Addition of CF4 to CH4 reduces the dielectric constant to 2.1 and raises the deposition rate. However etching reaction occurs with high CF4/CH4 ratios. No film grows with only CF4. XPS measurement reveals that the F atoms are introduced into the amorphous carbon films. Helicon reactor has higher plasma density and is expected to achieve higher deposition rate for productive use. In this reactor, fluorinated amorphous carbon films without hydrogen content can be obtained with only CF4 and C2F6 gases. The growth rate of the films reaches 0.3 μ/min with C2F6 and 0.15 μ/min with CF4 at a source power of 2 kW and a gas flow rate of 100 sccm. With heating up to 300°C in a vacuum for 1 hour, the thickness of the films deposited with C2F6 does not shrink while that of films with CF4 shrinks.
Material Characterization Of Methyl Siloxane Sogs
Authors: Numata Ken , Seha Thomas R. , Jeng Shin-Puu , Tanaka Tsuyoshi 
Published: April 2011

AbstractMethyl siloxane spin-on-glass (SOG) is a conventional gap-filling material. In accordance with the requirement of low permittivity, many of major SOG suppliers are developing new types of methyl siloxane SOGs.The most interesting property of these SOGs is their permittivity, which we measured by making stack structures of Al-0.5%Cu / TEOS CVD SiO2 / SOG / n+ Si. We also studied I-V characteristics, refractive indices, FT-IR spectra, stress, and moisture resistance.All of the SOGs showed small stress and fair moisture resistance. Leakage currents were less than 2.5E-10 A/cm2 for bias voltages up to 5V. Permittivities ranged from 2.9 to 3.6. We observed a correlation between permittivity and FT-IR spectral features associated with Si-O-Si bonds. Reducing the number density of Si-O-Si bonds may be an effective way to lower the permittivity of this class of SOGs
Silica Aerogel: An Intrinsically Low Dielectric Constant Material
Authors: Hrubesh Lawrence W. 
Published: April 2011

AbstractSilica aerogels are highly porous solids having unique morphologies in which both the pores and particles have sizes less than the wavelength of visible light. This fine nanostructure modifies the normal transport mechanisms within aerogels and endows them with a variety of exceptional physical properties. For example, aerogels have the lowest measured thermal conductivity and dielectric constant for any solid material. The intrinsically low dielectric properties of silica aerogels are the direct result of the extremely high achievable porosities, which are controllable over a range from 75% to more than 99.8%, and which result in measured dielectric constants from 2.0 to less than 1.01. This paper discusses the synthesis of silica aerogels, processing them as thin films, and characterizing their dielectric properties. Existing data and other physical characteristics of bulk aerogels (e.g., thermal stablity, thermal expansion, moisture adsorption, modulus, dielectric strength, etc.), which are useful for evaluating them as potential dielectrics for microelectronics, are also given.
Methods And Needs For Low K Material Research
Authors: Ting Chiu H. , Seidel Thomas E. 
Published: April 2011

AbstractFor several years the industry has recognized the need of developing low k dielectric material and high conductivity metal for high performance interconnect. Low k dielectric will impact both power and delay favorably, while higher conductivity metal will reduce delay time. In order to be useful, new low k dielectric materials must be carefully characterized for their electrical, chemical, thermal and mechanical properties. In addition, their impact on process integration, fabrication cost and device reliability must also be considered. Since the gestation period for introducing a new material is very long, a set of standard testing methodologies are required to speed up the development process. This review will discuss various material options and the progress of material development and characterization methodologies. Example results will be provided for assessing these parameters.
Vapor Deposition Of Very Low K Polymer Films, Poly(Naphthalene), Poly(Fluorinated Naphthalene)
Authors: Lang C. -I. , Yang G. -R. , Moore J. A. , Lu T. -M. 
Published: April 2011

AbstractSeveral novel processes have been developed in our lab to synthesize and deposit polymers that have extremely low dielectric constants (below 2.5) as thin films. These reactive intermediates are condensed onto wafers in a vacuum chamber and no chemical waste is produced. Furthermore, cold traps can be used to recover uncondensed monomers through the pumping system. Because of the extremely low dielectric constant, very low moisture uptake and high temperature stability of these vapor depositable materials, these environmentally friendly polymers are very attractive for future electronic applications as interlayer dielectrics. Examples are Parylene-F(fluorinated), poly(naphthalene) (PNT-N), poly(fluorinated naphthalene) (PNT-F), and Teflon AF 1600 (amorphous). These films were deposited at substrate temperatures between −20 and 350 °C and at deposition pressure was 10−4−2.5 Torr. The film thicknesses were between 0.1–10 μ. and dielectric constants were between 1.9–2.5. The thermal stabilities of these films were between 360–590 °C. Among them, poly(fluorinated naphthalene) dissociates at about 590 °C. Poly(naphthalene) and poly(fluorinated naphthalene) are obtained as films by vaporizing monomers in vacuo and transporting the vapor to a hot surface.
Substrate Effects on The Nucleation and Growth of GaSe Layers by Van Der Waals Epitaxy
Authors: Rumaner Lee E. , Gray J.L. , Ohuchi F.S. , Ueno K. , Koma A. 
Published: April 2011

ABSTRACTEpitaxial thin film multilayers are limited by the need for both lattice and thermal expansion matching. Recently, a new deposition technique, known as van der Waals epitaxy, has been developed to overcome these limitations. Van der Waals Epitaxy (VDWE)promises the ability to deposit multilayers based on the property of interest without being limited by lattice and thermal expansion mismatch. The crystallographic two dimensional metal chalcogenides are characterized by strong covalent bonding within a layer and weak van der Waals bonds between layers. By combining the layered nature of the metal chalcogenides with other layered materials as well as crystallographic 3D materials, oriented single crystal layers can be deposited, resulting in novel structures with atomically abrupt interfaces. However, even with the weak van der Waals bond, substrate/film interactions play a large role in the final structure.To study the substrate/film interaction occurring during van der Waals Epitaxy growth on 3D surfaces, the metal chalcogenide GaSe has been systematically deposited on GaAs(1 11) substrates. To develop an understanding of the interaction of the substratewith the growing film, growth of GaSe on both atomically rough and smooth substrates was studied. Comparison of the information developed through RHEED, TEM and AFM have been used to understand the basic nucleation and growth process as well as the observation and formation of film defects.
Aluminum/Copper Nanocomposites Fabricated by The Jet Vapor Depositiontm Process
Authors: Lankey Rebecca L. , Hsiung L.M. , Wadley H.N.G. , Karecki S.M. , Smith D.T. , Halpern B.L. , Schmitt J.J. 
Published: April 2011

ABSTRACTAluminum and copper nanolaminates have been fabricated at Jet Process Corporation using the novel, proprietary Jet Vapor DepositionTM (JVD)TM process. Laminates with a total thickness of 10 μm were made by depositing alternating layers ofapproximately equal thicknesses of copper and aluminum onto preheated silicon wafers at asubstrate temperature of ∼140 °C. The layer thicknesses were systematicallyvaried between 20 nm and 1 μm. The microstructure and properties of the laminates were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nanoindentation methods. TEM has shown that the laminates have a strong {111} texture. The hardness results show that above a critical layer thickness of approximately 50 nm, the yield strength of the composites varies inversely with thelayer thickness, while the strength of nanolaminates with layer thicknesses smaller than the critical thickness is better explained by the Koehler model. An alternative model recently proposed by Embury and Hirth fits the data equally well.