bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evolutionary Growth Development in SiC Sputtered Films
Authors: Roy R. A. , Messier R. 
Published: April 2011

AbstractThe growth of rf-sputtered silicon carbide thin films has been studied over a wide range of substrate temperatures, producing films with crystal structures from completely amorphous to highly crystalline. The initial 100nm of growth is characterized by ‘void network’ type physical structure throughout the temperature regime studied. This network of polyhedra outlines the dominant physical structure features at the top surface of the film and is shown to grow in average lateral dimension (D) with increasing film thickness (t) as a parabola (D=K·tx). The growth exponent (x) describes the lateral growth rate of these parabolic growth cone columns and decreases with increasing film temperature, bombardment, and hydrogen in the plasma. In the highly crystalline films the lateral crystallite growth rate eventually exceeds the growth of void network columns present in 10–100nm films, producing abrubt increases in size of physical features between 100–1000nm levels. The results show that the evolutionary structure zone model consistently accounts for film growth behavior in the amorphous regime but must be modified for crystalline films.
Ion Bombardment Effect on the Properties of a-Si:H
Authors: Drevillon B. , Schmitt J. P. M. 
Published: April 2011

AbstractIn a low pressure multipole plasma, the energy of the charged species impinging on the substrate can be varied electrostatically. Spectroscopic ellipsometry is used to study the film growth and the surface morphology. Hydrogen evolution is used to investigate the release of hydrogen from the amorphous network. Moderate energy ion bombardment (Eion ‰ 50 eV) is shown to favour the formation of homogeneous high density films with a sharp interface. Weak ion bombardment (Eion ‰ 20 eV) results in a microscopically rough surface. The material strucbural variations are evidenced by hydrogen evolution kinetics.
Low Temperature Plasma Anodization of Silicides
Authors: Perriere J. , Siejka J. , Laurent A. , Enard J. P. , D'heurle F. 
Published: April 2011

AbstractIn the first time, hundreds nm thick oxide layers were formed by room temperature plasma anodization of some refractory disilicides. Nuclear microanalysis and Rutherford backscattering techniques were used to study the anodic oxidation of various metal silicides (Hf, Ti and Zr) in a multipolar oxygen plasma set-up. We have found that the low temperature (<100 °C) plasma anodization kinetics of Hf or Zr silicides is two orders of magnitude higher than that of Ti silicide although their thermodynamic and physicochemical behaviour are very similar. 200 nm thick Hf (or Zr) and Si mixed oxide layers have been obtained in one hour plasma anodization. Analysis of RBS spectra indicates that the ratio of Si to metal cation concentration in the bulk of oxide grownis the same than the silicide (HfSi2 or ZrSi2), while in the near surface region of oxide (20 to 30 nm) there is an enrichment in metallic oxide leading to a Si to Hf (or Zr) concentration ratio equal to unity. The spectacular difference between the anodization rates in oxygen plasma of Hf (and Zr) silicides comparing to Ti silicides can be related to the catalytic effect on plasma anodization of the Hf and Zr oxides.
Thermal Nitridation of Silicon in Nitrogen Plasma and Nitrogen-Hydrogen Plasma
Authors: Matsumoto S. , Nakamura H. , Eguchi S. , Fujita S. , Sasaki A. 
Published: April 2011

AbstractThermal nitridation of silicon in both nitrogen and nitrogen-hydrogen plasma has been performed around 1000°C for 5 min to 10 hr. From Auger electron spectroscopy analysis, the formed films contain some oxygen and are identified as oxynitride films in both cases. In nitrogen-hydrogen plasma, high nitrogen fraction( 0.8) in the film is obtained for the nitridation of 5 min. Thus, the addition of hydrogen to nitrogen enhances the nitrgen fraction in the film for such a short nitridation time. The film thickness is almost constant against the nitridation time and is limited to be about 40 Å. Capacitance-voltage characteristics of aluminum gate metal- nitride-semiconductor capacitors show stable behaviors and the fixed charge density at the film-substrate interface is estimated to be the order of 1012 cm−2 in both cases.
Application of Plasma Anodization Technique to Device Fabrication
Authors: Sugano Takuo 
Published: April 2011

AbstractApplications of plasma anodization technique to Si, GaAs and InP dev-ices fabrication, demonstrated by the author's group, are reviewed. The feature of the technique is an electric field enhanced low temperature oxidation process. Suppression of the generation of oxidation induced stacking faults, the redistribution of impurities in the substrates and the bird's beak formation in selective oxidation process is an advantage in silicon technology. It must be stressed that plasma anodization is only one technique which has been proved to be successful in growing native oxide films on InP substrates for MISFETs fabrication.
Plasma Passivation Scheme for III–V Compound Semiconductor Surfaces
Authors: Theeten J. B. , Gourrier S. , Friedel P. , Taillepied M. , Arnoult D. , Benarroche D. 
Published: April 2011

AbstractPassivation of III-V compounds, especially GaAs, is still a major problem. Surface mechanisms related to stoichiometry defects (free As formation, vacancies) play an important role in the detrimental effects observed on GaAs devices (interface traps, leakage currents, parasitic transients …).We first analyze the phenomena occuring at GaAs (100) surfaces exposed to several (H2,N2 ) multipolar plasmas, with the following methods : - in situ study of the surface morphology and roughness using ellipsometry and electron diffraction - chemical analysis using photoemission and Auger spectroscopy - electrical analysis in situ (Fermi level position deduced from photoemission, work function measurements) or ex situ (device characterization, C(V) analysis).Using H2 based plasma treatments, a complete cleaning (oxide and contamination removal) can be obtained at moderate (below 200 °C) temperatures. This process, associated with surface nitridation and dielectric deposition, yield improved surface properties (lower recombination velocity and reduction of devices parasitic effects).The case of Ga1−xInxAs (100) surfaces (with x varying from 0 to 0.53)is then discussed and a comparative study is given, indicating that native nitridation may also be a good solution,in this case.
Time Resolved Diagnostics of RF Plasmas: a Fluid Model for ion Concentrations in the Sheath
Authors: Gottscho Richard A. 
Published: April 2011

AbstractA one-dimensional fluid model is presented for time-dependent ion concentrations in chlorine containing discharges. The ion formation rate is determined from experimental plasma-induced emission intensities. The local field is estimated from spectrally resolved laser-induced fluorescence data obtained in similar, BCl3 discharges. Quantitative agreement with experiment is obtained implying that the basic assumptions in the model are valid: (1) ground state ions in the sheath are formed predominantly by electron-impact ionization; (2) Cl2+ ion motion is mobilitylimited by charge exchange collisions with Cl2 neutrals; (3) the degree of Cl2 dissociation is ∼. 65% at a power density of 1.8 W cm−3; (4) the ion concentration near the electrode is spatially uniform throughout most of the rf cycle; and (5) there are two times during a low frequency rf cycle when ions experience a strong extraction force.Semi-empirical models like the one described here should be useful in computational optimization of plasma processes such as etching and deposition, which are in wicre-spread use throughout the microelectronics industry.
Effects of Gallium Arsenide Passivation on Scanning Tunneling Microscope Excited Luminescence
Authors: Reuter E. E. , Gu S. Q. , Bohn P. W. , Dorsten J. F. , Abeln G. C. , Lyding J. W. , Bishop S. G. 
Published: April 2011

ABSTRACTAn ambient scanning tunneling microscope (STM) was used to excite luminescence in ptype epitaxial GaAs with four separate surface preparations: bare GaAs, Au layer, sulfurmonochloride layer, and one monolayer of octa-decyl-thiol. The STM with tungsten tip was operated at a constant tunnel current of 5 nA during a +1 V bias applied to the sample and the resulting tip to sample distance was fixed during a higher voltage bias pulse which excited luminescence. The luminescence intensity increased rapidly with increasing bias voltage for all passivation types with the octa-decyl-thiol passivation achieving the highest STM excited luminescence (STMEL) of 3500 photons/sec at 4 V bias. Above about 4 V the luminescence from the octa-decyl-thiol and sulfur-monochloride passivated samples fell off irreversibly, indicating that the sample surface had been modified. The Au passivated and unpassivated samples showed no such luminescence drop up to 4.8 V, the highest bias employed. Photoluminescence (PL) studies of the samples showed that PL intensities exhibited a weaker dependence upon passivation type than did STMEL intensities, a result consistent with the assertion that STMEL is more sensitive to the surface properties of the sample than is PL.
Direct Nanoscale Patterning by Atomic Manipulation
Authors: Salling Craig T. 
Published: April 2011

ABSTRACTThe ability to create atomic-scale structures with the scanning tunneling microscope (STM) plays an important role in the development of a future nanoscale technology. I briefly review the various modes of STM-based fabrication and atomic manipulation. I focus on using a UHV-STM to directly pattern the Si(001) surface by atomic manipulation at room temperature. By carefully adjusting the tip morphology and pulse voltage, a single atomic layer can be removed from the sample surface to define features one atom deep. Segments of individual dimer rows can be removed to create structures with atomically straight edges and with lateral features as small as one dimer wide. Trenches ∼3 nm wide and 2–3 atomic layers deep can be created with less stringent control of patterning parameters. Direct patterning provides a straightforward route to the fabrication of nanoscale test structures under UHV conditions of cleanliness.
Molecular Beam Epitaxy Of Si/ZnS/Si(100) Heterostructures For Silicon-Based Quantum Devices
Authors: Zhou Xiaochuan , Li Feng , Spencer Gregory F. , Kirk Wiley P. 
Published: April 2011

ABSTRACTSpecial methods were developed to grow Si/ZnS/Si heterostructures for the purpose of developing silicon-based quantum devices. An arsenic passivation technique was used on silicon surfaces for the growth of ZnS. The effectiveness of this surface passivation was demonstrated by the improved crystal quality and decreased heterostructural interface-state density. A two-step growth method was developed for the epitaxial growth of silicon on ZnS surfaces. In this method the normal silicon epitaxial growth was preceded by a solid phase epitaxy process. Single crystal films of silicon were successfully grown on ZnS surfaces. Our discussion addresses two key issues: crystal defects and the density of interface states. The results of RHEED (reflection high energy electron diffraction), C-V (capacitance voltage), and SIMS (secondary ion mass spectroscopy) measurements are presented.
Nanoscale Features Grown by MBE on Nonplanar Patterned Si Substrates
Authors: Hobart Karl D. , Kub Fritz J. , Gray Henry F. , Twigg Mark E. , Park Doewon , Thompson Phillip E. 
Published: April 2011

ABSTRACTSi growth by molecular beam epitaxy on nonplanar patterned Si substrates is studied as a function of growth parameters. The substrates consist of a truncated pyramid template with {111} sides and (100) tops formed by anisotropic etching of Si(100). For growth temperatures ≤ 550°C no qualitative changes in the morphology of the template are observed. At growth temperatures between 650–700°C {113} facets begin to form on the (100) surface and reduce the lateral dimensions of the (100) facet to < 20 nm. At high temperatures (∼800°C) {113} facets remain stable and {111} facets no longer exist. The small (100) mesa formed at medium temperatures by facet reduction is exploited through the growth of Si/Si 1-xGex multiple quantum wells leading to low-dimensional structures. Observations are quantified by scanning electron and transmission electron microscopies.
Low-Dielectric Constant Film Formation By Plasma Fluorination Of Hydrocarbon Polymers
Authors: Kudo Hiroshi , Shinohara Rika , Yamada Masao 
Published: April 2011

AbstractWe have investigated plasma fluorination of hydrocarbon polymer films spincoated onto silicon wafers. Fluorinated hydrocarbon polymers gave low dielectric constants of 2.0 – 2.4 which was close to that of PTFE. However, the thermal stability of these fluorinated polymers inferior to that of the non-fluorinated polymers. We believe that this is due to a decrease in the molecular weight resulting from C-C bond cleavage. We think that such a side reaction will be controlled by removing residual oxygen in a fluorination chamber. The molecular structures of the fluorinated polymers were analyzed by X-ray photo emission spectroscopy. Finally, we proposed direct patterning of interlayer dielectrics using plasma fluorination.
Thermal And Mechanical Properties Of Low K Polymers
Authors: Chiang Chien , Mack Anne S. , Pan Chuanbin , Ling Yui-Lin , Fraser David B. 
Published: April 2011

AbstractLow dielectric constant polymers offer many advantages in circuit performance, such as power dissipation, crosstalk and RC delay, when used as inter-layer dielectrics (ILDs). Silicon dioxide, a material commonly used as an ILD has a dielectric constant of 4.0. Organic polymers that have dielectric constant values ranging from 2.0 to 3.0 offer attractive alternatives to SiO2. However, it has been a great challenge to find organic polymers with thermal stability up to 450 °C. We have characterized thermal properties of polymers using thermal desorption analysis. isothermal TGA and FTIR to identify weak functional groups. In addition, we have measured the hardnesses and moduli of these polymers and found that the values are much lower than those of SiO2.Stress distributions in the interconnect system were analyzed using finite element modeling in order to understand potential reliability problems.
Thermal And Mechanical Properties Of Polyimide Films
Authors: Chen S. T. 
Published: April 2011

AbstractIn recent years, polyimide film has become a commonly used insulator for microelectronic devices including advanced semiconductor chip and high density packaging. It has the advantages of low dielectric constant, thermal stability and low processing cost. In general, it is important to understand both the thermal and mechanical properties of a microelectronic material. Thermal and mechanical properties play very important roles in terms of determining the device structural integrity. Mismatch of material properties could cause feasibility and reliability problems. These properties are also essential for mechanical stress and thermal stress modeling studies. Biphenyldianhydride-Phenylenediamine (BPDA-PDA) and Pyromellitic Dianhydride-Oxydianiline (PMDA-ODA) are two commonly used polyimide films in electronic industry. Their thermal expansion coefficients and mechanical properties were studied and reported here.
Fluorinated, Low Thermal Expansion Coefficient Polyimides For Interlayer Dielectric Application: Thermal Stability, Refractive Index And High Temperature Modulus Measurements
Authors: Auman Brian C. 
Published: April 2011

AbstractThe mechanical, thermal, electrical and moisture absorption properties of rod-like, fluorinated polyimides and copolyimides developed in our laboratory are briefly reviewed. Further characterization work on the most promising candidates for interlayer dielectric applications is reported. This includes in- and out-of-plane refractive index measurements to estimate the isotropy of the dielectric constant, isothermal TGA measurements to assess thermal stability at processing temperatures and dynamic-mechanical analysis to ascertain the glass transition temperature and the mechanical modulus at temperatures in excess of the glass transition
Preparation Of Low-Density Xerogels At Ambient Pressure For Low K Dielectrics
Authors: Smith D. M. , Anderson J. , Cho C. C. , Johnston G. P. , Jeng S. P. 
Published: April 2011

AbstractLow density silica xerogels have many properties which suggest their use as a low dielectric constant material. Recent process improvements to control capillary pressure and strength by employing aging and pore chemistry modification, such that shrinkage is minimal during ambient pressure drying, have eliminated the need for supercritical drying. Although xerogels offer advantages for intermetal dielectric (IMD) applications because of their low dielectric constant (<2), high temperature limit, and compatibility with existing microelectronics precursors and processes, they suffer from unanswered questions. These include: 1) are all pores smaller than microelectronics features, 2) what are their mechanical properties (for processing and particle generation), and 3) what is their thermal stability. We have produced bulk xerogels under similar conditions to those used for films and studied the effect of density on the pore size distribution and bulk modulus.
Evaluation Of Amorphous Diamond-Like Carbon And Boron Nitride Films As Low Permittivity Dielectrics
Authors: Sullivan J. P. , Friedmann T. A. , Apblett C. A. , Siegal M. P. , Missert N. , Lovejoy M. L. , Mirkarimi P. B. , McCarty K. F. 
Published: April 2011

AbstractAlthough films of diamond-like carbon (DLC) and hexagonal boron nitride (h-BN) have shown low dielectric constants in the range of 3 to 4, these materials have been unsuitable for use as interconnect dielectrics due to poor thermal stability and environmental degradation. These deficiencies can be addressed by depositing DLC films free of hydrogen (a-tC) and depositing the cubic phase of BN (c-BN). The dielectric characteristics of hydrogen-free DLC and c-BN that have been deposited by pulsed-laser deposition (PLD) have been evaluated using metal-insulator-metal and metal-insulator-semiconductor structures. For comparison, the dielectric characteristics of h-BN deposited by electron cyclotron resonance (ECR) were also evaluated. Despite the superior thermal and environmental stability of the a-tC and c-BN films and the attractively low deposition thermal budget (room temperature deposition for a-tC films, 400°C for c-BN films), the films exhibit dielectric constants comparable to those of bulk diamond and bulk BN, ∼ 6. Furthermore, the a-tC and c-BN films exhibit high compressive stress in the GPa range which limits their usefulness only to those applications requiring a thin dielectric layer, e.g. diffusion barriers or encapsulants.
Elastic Properties of Pure and Hydrogenated Ce/Fe Multilayer Films
Authors: Hassdorf R. , Arend M. , Felsch W. 
Published: April 2011

ABSTRACTThe study of the elastic properties of pure Ce/Fe multilayers throughout the structural phase transition of the Fe layers from crystalline to amorphous reveals striking similarities to the crystal-to-glass transition in bulk metallic materials which is driven by a shear instability of the crystal lattice. The transition is reflected in a pronounced minimum (∼ –70%) of the flexural modulus of the multilayers as determined by a vibrating-reed technique. Hydrogenation leads to multilayers composed of CeH∼2/Fe, with distinctly different moduli depending on the texture of the Fe sublayers. For multilayers with a Fe (111) texture a reorientation transition of the spontaneous magnetization is observed at a well-defined temperature. This transition is accompanied by a relaxation of thermal stresses and a considerable softening (∼30%) of the flexural modulus.
An in Situ High Voltage Electron Microscopy Technique for the Study of Deformation and Fracture: in Multilayered Materials
Authors: Wall M.A. , Barbee T.W. , Weihs T.P. 
Published: April 2011

ABSTRACTA novel, in situ, high voltage electron microcopy technique for the direct observation of the micromechanisms of tensile deformation and fracture in nanostructured materials is detailed. This technique is particularly well suited for the dynamic observations of deformation and fracture in multilayered materials. The success of this type of in situ technique is highly dependent upon unique specimen preparation procedures and sample design, the importance thereof will be discussed. The initial observations discussed here are expected to aid in our understanding of the mechanical behavior of this new class of atomically engineered materials.
Reactive Phase Formation in Sputter-Deposited Ni/Al Thin Films
Authors: Barmak K. , Michaelsen C. , Bormann R. , Lucadamo G. 
Published: April 2011

ABSTRACTWe have investigated reactive phase formation in magnetron sputter-deposited Ni/Al multilayer thin films with a 3:1 molar ratio and periodicities ranging from 2.5-320 nm. In addition, we studied the transformation of a codeposited film of the same composition. We find that an amorphous phase has already formed during deposition, and that the extentof formation of this phase increases with decreasing periodicity. The first crystalline phase then nucleates from this amorphous phase upon annealing. The formation of the amorphous phase considerably reduces the driving force and explains why during subsequent reactions nucleation kinetics become important. We obtain Ni2Al9 as the first product phase during heat treatment in some cases before NiAl3 occurs. For films with modulation periods larger than 40 nm, formation of NiAI3 is a two stage process as reported earlier, with the first stage being due to nucleation and growth to coalescence of NiAl3 grains, and the second stage being the growth of NiA13 normal to the initial interface until the reactant phases are consumed.
Specular and Off-Specular X-Ray Scattering as Quantitative Structural Probes of Multilayers. Application to MN/IR(111) Superlattices
Authors: Fischer H.M. , Fischer H.E. , Bessiere M. , Bobo J.-F. , Lenoble O. , Andrieu S. , Piecuch M. 
Published: April 2011

ABSTRACTDiffuse scattering of X rays is a particularly useful tool for studying interface and surface defects in single layer films. We have extended this technique to the study of multilayers. The samples are Mn/Ir(111) superlattices where Mn is pseudomorphic to Ir. We have studied three typical samples prepared at different substrate temperatures. Using theoretical analyses and simulations of both specular and off-specular X-ray scattering data at small angles as well as large angles, we show that large length-scale interfacial roughness is mainly due to the formation of terraces during growth at low deposition temperature, whereas small length-scale interfacial roughness occurs preferably at high deposition temperature and is mainly due to an atomic interdiffusion (i.e. the formation of an interface alloy) which manages to maintain a high degree of crystallographic order.