bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conductivity and Noise Measurements in 3D Percolative Cellular Structures
Authors: Chiteme C. , McLachlan D. S. 
Published: April 2011

ABSTRACTConductivity results and 1/f noise (Sav) measurements from some systems with a cellular structure (composites in which small conductor particles embed on the surface of larger and regular insulator particles) are given. The usual DC percolation parameters (φc,t & s) were obtained from fitting the results to the Percolation equations. φc values for the systems have been found to lie in the range 0.01 – 0.07, while both non-universal and close to universal values have been measured for the exponents s and t. In addition, 1/f or flicker noise results on the systems give an additional exponent ω from the relationship Sav/Vdc2 = KRω. For the systems measured so far, the exponent ω is observed to take different values ω1 close to and ω2 further away from the conductor-insulator transition, but on the conducting side (ω > ωc). The very different values (s, t & ω), obtained for the various conducting powders, in the same macroscopic structure, indicates that the way the powders distribute themselves on the insulating particles is a major factor in determining the exponents.
Electromechanical Study of Carbon Fiber Composites
Authors: Wang Xiaojun , Fu Xuli , Chung D.D.L. 
Published: April 2011

ABSTRACTElectromechanical testing involving simultaneous electrical and mechanical measurements under load was used to study the fiber-matrix interface, fiber residual stress and marcelling (fiber waviness) in carbon fiber composites. The interface study involved single fiber pull-out while the fiber-matrix contact resistivity was measured. The residual stress study involved measuring the resistance of a single fiber embedded in the matrix while the fiber was tensioned at its exposed ends. The marcelling study involved measuring the resistance of a composite in the through-thickness direction while tension was applied in the fiber direction.
Electrical Measurement of the Bandgap of N+ and P+ SiGe Formed by Ge Ion Implantation
Authors: Nishiyama Akira , Arisumi Osamu , Yoshimi Makoto 
Published: April 2011

ABSTRACTN+ and p+ SiGe layers were formed in the source regions of SOI MOSFETs in order to suppress the floating-body effects by means of high-dose Ge implantation. The bandgaps of the layers were evaluated by measuring the temperature dependence of the base current of the source/channel/drain lateral bipolar transistors. It has been found that the reductions of the bandgaps due to the SiGe formation by the Ge implantation were relatively small, compared to those obtained by the theoretical calculation for heavily doped SiGe. It was also found that the bandgap reduction was larger for n+ layers than that for p+ layers.
In situ Characterization of Functional Organic Thin Films by Energy Dispersive Grazing Incidence X-ray Diffraction
Authors: Yoshida Yuji , Takiguchi Hiroshi , Tanigaki Nobutaka , Yase Kiyoshi 
Published: April 2011

ABSTRACTWe are investigating well-ordered highly crystalline thin films made using organic molecular beam deposition (OMBD) since it is important to control the formation mechanism at the initial growth process. Then, we developed a new in situ technique of energy dispersive grazing incidence X-ray diffraction utilized within an ultrahigh vacuum system. This technique (in situ ED-GID) makes it possible to examine the crystal structure, orientation and morphology of organic thin films during deposition without any damage to the film. In the present review, we examined the growth process of thin films of functional organic dyes, fullerene (C60) and p-sexiphenyl (6P) by using this in situ ED-GID. The crystal strucutre and molecular orientation in epitaxially-grown thin films were confirmed during the initial stages of growth. Also, the morphology of C60 thin films was examined during the deposition. As a result, it was confirmed that the decay curves of X-ray fluorescence indicate different island growth in C60 thin films.
Monitoring of Sidewall Spacer Etch by Optical Emission Spectroscopy and Mass Spectroscopy
Authors: Min K. , Chambers J. J. , Parsons G. N. , Hauser J. R. 
Published: April 2011

ABSTRACTSelective etch of SiO2/poly Si in a high density CF4+D2 plasma generated by ECR (Electron Cyclotron Resonance) system was studied. The end point detection of the SiO2 sidewall spacer etch was monitored using optical emission spectroscopy and mass spectrometer. SEM cross sectional analysis was conducted to confirm the end point detection and spacer formation.
Rotating-Compensator Multichannel Ellipsometry: Applications in Process Development for Nanocrystalline Diamond Thin Films
Authors: Collins R. W. , Lee Joungchel , Rovira P. I. , An Ilsin 
Published: April 2011

ABSTRACTA multichannel spectroscopic ellipsometer based on the rotating-compensator principle was developed and applied to characterize nanocrystalline diamond thin film growth processes by plasma-enhanced chemical vapor deposition (PECVD). With the newly-designed instrument, a time resolution of 32 ms is possible for spectra (1.5˜4.0 eV) in the Stokes vector of the light beam reflected from the surface of the growing film. Several advantages of the rotating-compensator over the simpler rotating-polarizer multichannel ellipsometer design are demonstrated here for diamond thin film growth. These include the ability to: (i) resolve the sign ambiguity in the p–s wave phase-shift difference Δ, (ii) obtain accurate Δ values for low ellipticity polarization states, and (iii) deduce spectra in the degree of polarization of the light beam reflected from the film/substrate. The degree of polarization has been applied to characterize the time evolution of light scattering during the nucleation of the diamond, as well as the time evolution of thickness non-uniformity over the probed area of the growing film. In this paper, a brief description of calibration and data reduction for the new instrument is also provided.
In-situ RF diagnostic for PECVD process control
Authors: Raoux S. , Liu K. S. , Guo X. , Silvetti D. 
Published: April 2011

ABSTRACTThe fabrication of advanced integrated circuits requires increased accuracy in process monitoring and active control. As higher production yields are required, the technology is moving from statistical process control to in-situ diagnostic techniques. A set of experiments was conducted to explore the feasibility of using radio frequency (RF) impedance probes to detect deviation of electrical characteristics of process chambers during wafer fabrication. A probe was integrated on a plasma-enhanced chemical vapor deposition (PECVD) chamber to explore the sensitivity of the reactor electrical characteristics on the events of process drift or input parameter variation. We measured RF the voltage, current and harmonics, the phase angle and the impedance magnitude for a capacitively coupled reactor. A single frequency (13.56MHz) process for depositing Si0 2 and a dual frequency (13.56MHz+35OkHz) process for Si3N4 deposition were characterized. We investigated the dependence of the RF signature and process parameters such as RF power, pressure, gas flow and electrode spacing. We observed that there is a correlation between the film properties (especially stress) and the plasma electrical characteristics. Furthermore, RF probes can be used to detect chamber malfunctions such as lost of RF ground or wafer-out-of-pocket events.
Characterization of a Solid-Source Delivery System for Metal Organic Chemical Vapor Deposition by In-Situ Laser Reflectance
Authors: Dubourdieu C. , Kim G. Y. , Meyer J. D. , Gallois B. 
Published: April 2011

ABSTRACTSpecular laser reflectance (He-Ne laser) has been used to monitor in-situ and in real time the growth rate and the index of refraction of oxide films during chemical vapor deposition. This technique has been implemented on an inverted vertical stagnation-flow reactor equipped with a solid-source delivery system. Yttria deposited on silicon has been chosen as a starting material to characterize the reactor and the precursor delivery system capabilities. The experimental reflectance curves have been fitted to a simple three-layer (gas/film/substrate) model allowing the determination of the growth rate and of the refractive index. The growth rate has been studied as a function of various key processing parameters: the source feeding rate, the powder packing density, the oxygen partial pressure and the total pressure. The change in reflectivity has also been recorded during pulsed-delivery growth. Nanometer-scale resolution is obtained which demonstrates that this method can be extended to the study of multilayer oxide structures.
Microstructure And Mechanical Properties Of Electroplated Cu Films For Damascene Ulsi Metallization
Authors: Dubin V. M. , Morales G. , Ryu C. , Wong S. S. 
Published: April 2011

ABSTRACTCopper has been deposited for filling sub-0.5 μm trenches by using electroplating. Electroplating with pulse plating conditions provides the high deposition rate (0.5–1 μm/min) and defect-free filling the 0.25 μm trenches and vias of high aspect ratio (>4:1). Enhanced copper electroplating at the trench bottom has been achieved. The median grain size of electroplated copper was measured to be about 1 jim and the lognormal standard deviation is about 0.4 μm. Strong <111> texture was observed in electroplated Cu film. Low stress of electroplated Cu films and excellent adhesion of plated Cu to sputtered Cu seed were observed.
Coherency and Loss of Coherency in Multilayers
Authors: Hazzledine P. M. , Grinfeld M. A. , RAO S. I. 
Published: April 2011

ABSTRACTA multilayer consisting of parallel sided, elastically isotropic layers with thicknesses much smaller than their dimensions in the plane of the layers may develop large coherency stresses when the layers are thin enough. General formulae are given for the stress tensors in a flat periodic fully coherent multilayer which may contain any number of layers, each with different lattice parameters, elastic constants and thicknesses. As the thicknesses of the layers increase there is an increasing tendency for the interfaces to become incoherent thereby relaxing the elastic stresses, at the expense of creating higher energy interfaces between the layers. This tendency is particularly marked for unusually thick or unusually rigid layers or for layers with very large or small lattice parameters. Unlike the case of thin films on massive substrates, there is no single thickness at which coherency is lost. In this paper, the loss of coherency is explored by searching for energy minima in irregular multilayers.
The Hardness and Wear of Electrochemically Grown Tantalum Oxide
Authors: Mulivor A. W. , Mann A. B. , Searson P. C. , Weihs T. P. 
Published: April 2011

ABSTRACTFor several metallic systems, including tantalum, barrier (non-porous) oxide layers up to 200 nm thick can be grown quickly and efficiently using electrochemical techniques. The thickness of the oxide layer has been found to be linearly proportional to the voltage applied during the electrochemical growth process. These oxides can cause a substantial increase in both the hardness and wear-resistance of the surface. Ex-situ Micro and Nano indentation testing of the Ta/ Ta2O5 system has clearly shown that the indentation hardness increases with oxide thickness, even for indentation depths much greater than the oxide thickness. AFM imaging of indentations and analysis of nanoindentation curves suggests this increased hardness is due to the oxide impeding the pile-up of material at the edges of the indentation, which changes the geometry of the contact. Tribometer testing of various oxide thicknesses has shown that the oxide plays a similar role in preventing wear, specifically by preventing the transfer of material between the two contacting bodies and spreading the load over a greater area. Thus, the electrochemical growth of Ta2O5 provides a convenient method for providing protective hard coatings.
Nucleation of Voids in Thin-Film Interconnects Through Crystallographic Slip
Authors: Shen Y.-L. 
Published: April 2011

ABSTRACTA two-dimensional void nucleation model in thin-film metal interconnects is proposed. The model is based on the evolution of stress and deformation fields obtained from numerical modeling. Interface flaws between the metal and the surrounding dielectric are assumed to exist. A unique pattern of shear stress resolved on the slip systems of the metal is found. A model of dislocation slip is constructed in accord with the evolution of the shear mode. The mechanism of crystallographic slip is such that lateral thinning of the metal line at the debond region, together with the slip steps produced at the edges of debond lead to a net transport of atoms away from the interface defect, and a physical void is thus formed.
A Novel Method to Measure Poisson's Ratio of Thin Films
Authors: Ziebart V. , Paul O. , Münch U. , Baltes H. 
Published: April 2011

ABSTRACTWe report a novel method to measure Poisson's ratio v of compressively prestressed thin films. The method exploits a v-dependent mechanical instability transition of buckled long rectangular membranes under differential pressure. This allows to determine v with high accuracy, using a physical model of the plate instability. The method was used to extract v = 0.253±0.017 from 0.704±0.003 μim thick PECVD silicon nitride films.
Creation and Motion of Edge Dislocations in Copper Single Crystals
Authors: Masaodoyama  , Kogure Yoshiaki , Nozaki Tadatoshi 
Published: April 2011

ABSTRACTDislocations were created near the center of the surface (110) of copper small crystals whose surfaces are (111), (111), (110), (110), (112), and (112) by use of n-body atom potentials and molecular dynamics. At first, a Heidenreich-Shockley partial dislocation was created. As the partial dislocation proceeds, the partial dislocation and the surface was connected with a stacking fault until the next Heidenreich-Shockley partial dislocation was created at the surface.Just before the creation of a partial dislocation the stress was the highest. For larger crystals, forming a step on (110) plane was not enough and a shear was necessary to move dislocations.
Internal Mechanical Stresses and Conductivity Mechanisms of p-n-InAsPSb/InAs-Heterostructures
Authors: Sidorov V. G. , Sokolov V. I. , Sidorov D. V. 
Published: April 2011

ABSTRACTInfluence of internal mechanical stresses (IMS) and dislocations on conductivity mechanisms and reliability of light emitting diode (LED) and laser InAsPSb/InAs double heterostructures has been investigated. It was shown that the presence of lattice mismatch of layers at p-n-heteroboundaries changes LED conductivity mechanisms the same way as longterm working challenges by current. It was determined that LED degradation has barrier character and is followed by appearance and growth of tunnel current components with power dependence of current from voltage. Reliability and external quantum efficiency decrease with growth of lattice mismatch.
The Mechanical Response of Thin Film Substrates Subject to Ultrasonic Joining
Authors: Krzanowski J. E. , Razon E. , Hmiel A. F. 
Published: April 2011

ABSTRACTThe ultrasonic wire bonding process is widely used for making interconnections between IC chips and package lead frames, yet the relationships between the wire/substrate materials properties and the bond formation processes are not yet well understood. In this study, we have conducted experiments to understand the mechanical response in thin film substrates subject to ultrasonic wire bonding. Atomic force microscopy (AFM) has been used to examine the morphology of thin film surfaces before and after bonding. Al wires were bonded to thin films of Cu, Cu-Ni and Ag, after which the aluminum wire was removed by etching. AFM examination of the Cu and Cu-Ni bonded surfaces revealed the extent of surface smoothing increased with bonding power level. However, at power levels typically employed in practice almost no morphological surface changes were observed, indicating surface smoothing is not required to obtain good bonds. TEM and SEM cross-sections were also used to examine Al wedge bonds and Au ball bonds to Al films on Si. A wide variety of features were observed, including surface smoothing, microcracking and void formation.
A Comparative Study of Residual Stresses in Single and Multilayer Composite Diamond Coatings
Authors: Jagannadham K. , Watkins T. R. 
Published: April 2011

ABSTRACTResidual stresses in four types of diamond films deposited by hot filament chemical vapor deposition on molybdenum substrate, three types on tungsten carbide or silicon nitride substrate are measured. Residual stresses are determined by X-ray method and Raman spectroscopy. The results from both these techniques are compared and conclusions are made on the mechanisms of adhesion of diamond films to the different substrates.
Surface and Interface Strains Studied by X-Ray Diffraction
Authors: Akimoto Koichi. , Emoto Takashi , Ichimiya Ayahiko 
Published: April 2011

ABSTRACTWe have developed a technique of X-ray diffraction in order to measure strain fields near semiconductor surface and interface. The diffraction geometry is using the extremely asymmetric Bragg-case bulk reflection of a small incident angle to the surface and a large angle exiting from the surface. The incident angle of the X-rays is set near critical angle of total reflection by tuning X-ray energy of synchrotron radiation at the Photon Factory, Japan. For thermally grown-silicon oxide/Si(100) interface, the X-ray intensity of the silicon substrate 311 reflection has been measured. From comparison of the full width at half maxima (FWHM) of X-ray rocking curves of various thickness of silicon oxides, it has been revealed that silicon substrate lattice is highly strained in the thin ( less than about 5 nm) silicon oxide/silicon system. In order to know the original silicon surface strain, we have also performed the same kind measurements in the ultra-high vacuum chamber. A clean Si(l 11) 7×7 surface gives sharper X-ray diffraction peak than that of the native oxide/Si(l 11) system. From these measurements, it is concluded that the thin silicon oxide film itself gives strong strain fields to the silicon substrates, which may be the reason of the existence of the structural transition layer at the silicon oxide/Si interface.
Correlation Between The Mechanical Stress And Microstructure In Reactive Bias Magnetron Sputtered Silicon Nitride Films
Authors: Kim Joo Han , Lee Won Sang , Chunga Ki Woong 
Published: April 2011

ABSTRACTThe influence of ion bombardment on the mechanical stress and microstructure of sputtered silicon nitride (SiNx) films has been systematically investigated. Applied substrate bias voltage was used to control the bombardment energy in a radio frequency (rf) reactive magnetron sputtering system. The resultant films were characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), Rutherford backscattering spectrometry (RBS), stress and chemical etch rate measurements. As the bias voltage was increased, the internal stress in SiNx films became increasingly compressive and reached a value of about 18.3 × 109 dyne/cm2 at higher bias voltages. These correlated well with the transition of the film microstructure from a porous microcolumnar structure containing large void to the more densely packed one. The obtained results can be explained in terms of atomic peening by energetic particles, leading to densification of the microstructure. It was also found that the amount of argon incorporated in the film is increased with increasing bias voltage, whereas the oxygen content is decreased. The lowest etch rate in buffered HF solution, approximately 1.2 Å/sec, was observed with the application of a substrate bias of -50 V.
Stress Evolution and Notch Formation During Polysilicon Gate Electrode Etching
Authors: Vyvoda Michael A. , Graves David B. 
Published: April 2011

ABSTRACTWe have developed a numerical simulation based on the boundary element method that models thermal contraction-induced stresses within semiconductor microstructures, and the effects of these stresses on surface evolution. The test case we have studied is that of polysilicon gate etch during over-etching in a plasma environment. We assume a local etch rate proportional to the normal component of the surface strain energy density gradient caused by the differential thermal contraction of polysilicon substrate and underlying silicon dioxide film. This leads to the prediction of stress-enhanced etching in the area near the polysilicon / gate oxide interface, where large stresses develop during cooling from deposition temperature to room temperature. It is proposed that stress-enhanced etching of this nature may be partially responsible for a common type of deleterious feature observed experimentally during gate electrode patterning known as “notching”.
Comparison Of Aln Films Synthesized By Pulsed Laser Ablation And Magnetron Sputtering Techniques
Authors: Jagannadham K. , Sharma A. K. , Wei Q. , Kalyanraman R. , Narayan J. 
Published: April 2011

ABSTRACTA comparative study is reported on the aluminum nitride (AIN) films on Si (111) substrate deposited by pulsed laser deposition and reactive magnetron sputtering. The structure, bonding characteristics, relative impurity levels, and wear resistance have been investigated to compare these films. We have used the techniques such as high resolution transmission electron microscopy, Raman spectroscopy, fourier transform infra-red spectroscopy, secondary ion mass spectrometry, and crater grinding method for wear test, to delineate differences between these AIN films.
Micromechanical Properties of Silicate Glass Films on Sapphire Substrates
Authors: Zagrebelny Andrey V. , Carter C. Barry 
Published: April 2011

ABSTRACTThe deformation of thin layers of glass on crystalline materials has been examined using newly developed experimental methods for nanomechanical testing. Continuous films of anorthite (CaAl2Si2O8), celsian (BaAl2Si2O8), and monticellite (CaMgSiO4) were deposited onto A12O3 surfaces by pulsed-laser deposition (PLD). Mechanical properties such as Young's modulus and hardness were probed with a high-resolution depth-sensing indentation instrument. Nanomechanical testing, combined with AFM in-situ imaging of the deformed regions, allowed force-displacement measurements and imaging of the same regions of the specimen before and immediately after indentation. Emphasis has been placed on examining how changes in the glass composition, residual stress introduced into the films, effect of film's heat-treatment, and the effect of substrate crystallographic orientation will affect the mechanical properties of silicate-glass films.
3D Discrete Dislocation Models Of Thin-Film Plasticity
Authors: Hartmaier A. , Fivel M. C. , Canova G. R. , Gumbsch P. 
Published: April 2011

ABSTRACTThree-dimensional simulation schemes for discrete dislocation dynamics (DDD) have been used successfully to investigate plasticity of bulk materials. The adaptation of these DDD schemes to a description of thin-film plasticity requires detailed modeling of the interfaces and surfaces of the film. One possible method is to compensate for the normal stresses that a dislocation distribution exerts on a surface by appropriate point loads. This traction-compensation method is extended to a free standing film (two opposing surfaces). The extension to a thin film on a substrate is possible.