bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adhesion of a-C:F during oxygen plasma annealing
Authors: Matsubara Y. , Endo K. , Tatsumi T. , Horiuchi T. 
Published: April 2011

AbstractFluorinated amorphous carbon (a-C:F) films sandwiched between layers of SiO2 have been proposed as an interlayer dielectric (ILD) structure in order to enhance resistance to oxygen plasma. This study describes adhesion failure mechanisms for the sandwiched fluorinated amorphous carbon film (a-C:F) structure during oxygen plasma annealing. We have found 3 failure modes: 1) capping SiO2 layer peels off, 2) thickness reduction of a-C:F by decomposition, and 3) etching phenomena at the interface between SiO2 and a-C:F by CFx outgassing from a-C:F. The outgassed CFx radicals were stored at the interfaces and the etching of SiO2 occurred during the subsequent 150°C oxygen plasma resist removal process. Thermal decomposition of a-C:F ILD sandwiched between layers of SiO2 was performed to determine the outgassed species, as well as the thickness reduction of a-C:F.
Physical Characterization of Photosensitive Polyimide
Authors: Zou Y.L. , Alford T.L. , Mayer J.W. 
Published: April 2011

AbstractPolyimides prepared from oxydiphthalic anhydride and diamine precursors can be photosensitive. The thermal, mechanical, and dielectric properties of the polyimide films have been characterized with various techniques. The thermal decomposition temperature of the cured film is 520 °C, and the coefficient of thermal expansion is 20 × 10−6/°C. The polymer chemistry and processing conditions result in a low stress (<26 MPa) in the polyimide film as measured in situ during the curing and cooling cycles. Pads of 6 μm were patterned through the photosensitive polyimide at a sensitivity of 110 mJ/cm2 to i-line wavelength. The polyimide films exhibit anisotropy with an in-plane refractive index of 1.74 and an oul-of-plane index of 1.62 measured at 632.8 nm wavelength. This indicates a preferred orientation of polymer chains in the film plane. The estimated dielectric anisotropy should be considered a major factor for device design and optimization.
Adhesion Strength and Deformation Behavior of Al(Cu-Si)/BPDA-PDA Layered Structures
Authors: Abramowitz P. , Ogawa E. , Ho P. S. , Wetzel J. 
Published: April 2011

AbstractThe adhesion of Al(Cu-Si) line structures on thin films of BPDA-PDA with different surface preconditioning were examined by measuring the deformation energy of the metal and interface. The properties of BPDA-PDA/Al(Cu-Si) were examined with atomic force microscopy (AFM). Although different sputtering treatments profoundly affect the adhesive properties, the sputtering does not appreciably change the topology of the BPDA-PDA. We also found evidence that even though the thickness of the interface can be very small (3–5 nm), the polymer/metal interface can greatly affect the deformation behavior of the entire system.
Material and Interface Characterization of Cu99Ti1 Thin Films Metallized on Polyimide
Authors: Kondoh E. , Nguyen T.P. 
Published: April 2011

AbstractCopper films with a small amount of an alloy element (1 wt % Ti) were metallized on polyimide. Plasma pre-treatment of the polyimide surface and post-metallization annealing were used to modify the interface. Interfaces and metal film layers were investigated; a drastic increase in adhesion strength, the suppression of Cu diffusion into polyimide, and the improvement of (111) texture were found. Composition analysis data taken from the interface indicated the accretion of nitrogen at the interface. The formation of Ti-related chemical bonds, suggested by X-ray photoelectron spectroscopy, can explain the above-mentioned experimental results.
The Preparation of Submicron Precision Cross Sections by Dimpling With A ‘Flatting Tool’
Authors: Humiston Helen L. 
Published: April 2011

AbstractThe complex materials systems in VLSI devices require specialized preparation techniques for TEM microstructural analysis. For this purpose, it is desirable to obtain electron transparency in all material layers from the oxides used in dielectrics to refractory metals such as tungsten. The primary advantage of dimpling these materials is that ideal specimens are obtained for low angle ion milling. By dimpling both sides of the cross section with a padded flatting tool, a thicker specimen of 130μm at the outer rim of the 3mm disc is produced that narrows to the 125nm thickness fringes in the center. These samples do not require a copper support grid, thereby allowing for a lower milling angle of 2.5 degrees on both sides of the specimen. This technique provides a cross section that is electron transparent in all layers without the loss of oxides due to differential thinning rates of various materials at higher milling angles.It is generally thought that precision thinning through a submicron feature is not possible on the dimpler. However, a simple step-by-step procedure for this technique will be demonstrated and discussed.
Applications of Reactive Gas Plasma Cleaning Technology in Minimizing Contamination Of Specimens During Transmission and Analytical Electron Microscopy
Authors: Roberts S. P. , Zaluzec N. J. , Walck S. D. , Grant J. T. 
Published: April 2011

AbstractThe generation and usage of a reactive gas plasma for a wide range of applications has been cited since the early 1970's. More recently, the use of a plasma generating system has been applied to analytical transmission electron microscopy to minimize and, in some cases, eliminate the problems associated with various contamination sources, including the specimen holder and the specimen itself. Although the technology is well known, no definitive characterization of process parameters has been developed for specimen and specimen holder cleaning applications. An investigation of the effects that power levels and gas mixtures have upon contamination rates and removal were done using a Philips CM30T. Measurements of contamination rates both prior to and following plasma cleaning were done to characterize the effects of various parameter changes. Results of different process parameters and contamination rates will be reported.
The Effects of Gas Composition on the Ion Milling of Cross Sectional Tem Samples Containing Carbon Layers
Authors: Walck Scott D. , Scheltens Frank J. , Nainaparampil Josekutty J. 
Published: April 2011

AbstractDuring conventional ion milling of carbon thin films on Si or SiC, the carbon has a much slower milling rate than the Si, SiC, and the epoxy resin. As a result, the substrates were thinned much more rapidly than the carbon films. A solution suggested by several subscribers to the Microscopy Society of America's Microscopy Listserver among others was to reactively ion mill the samples with a 20–25% oxygen-argon gas mixture. Is this the best inert gas to use? Neon has a mass that is between Si and C and therefore should impart a higher energy transfer to the C atoms than Ar. To determine whether the mass of the inert gas is important in balancing the milling rates, four gases were used to ion mill samples of a PLD DLC film with a nominal thickness of 0.5 μm. For improved adhesion of the films to the Si substrate, an initial 2 nm of Ti and a nominal 0.5 μm thick layer of TiC was grown using a combined PLD and magnetron sputtering technique prior to the PLD DLC.1,2 The gases were 100%Ar, 100%Ne, 75%Ar-25%O2, and 75%Ne-25%O2. Using the Tripod Polisher, the samples were polished flat using typical conditions and the surfaces examined by atomic force microscopy and compared. TEM samples prepared by single-sided dimpling prior to ion milling were prepared using the gas composition which gave the best results with respect to the AFM. A methodology is established for determining ion milling conditions for samples having layers of different compositions.
Cross-Sectional Tem Sample Preparation Method Using Fib Etching for Thin-Film Transistor
Authors: Tsujimoto K. , Tsuji S. , Takatsuji H. , Kuroda K. , Saka H. , Miura N. 
Published: April 2011

AbstractA rapid and precise sample preparation method using focused ion beam (FIB) etching was developed for cross-sectional transmission electron microscopy (X-TEM) analysis of a thin-film transistor (TFT) fabricated on a glass substrate. Gallium (Ga) ions accelerated at 30 kV and at various incident beam angles were applied during FIB etching to create a uniform thin wall. We successfully prepared X-TEM specimens of long and fragile aluminum (Al) whiskers formed on thin Al films in TFT metallization, where a strong charge is built up during FIB etching. The effect of ion-beam-assisted tungsten deposition prior to FIB etching is discussed. A whisker having a length not exceeding approximately 10 #x00B5;m can be successfully etched to a thickness of 200 nm while keeping its original shape. The performance of this technique is demonstrated in applications to etching at other fragile locations related to TFTs.
Cross sectional Tem Sample Preparation Using E-Beam Lithography and Reactive ion Etching
Authors: Cho Hyun-Jin , Griffin Peter B. , Plummer James D. 
Published: April 2011

AbstractA simple method to make cross sectional TEM samples of Si and GaAs semiconductor devices at specific device locations using electron beam (e-beam) lithography and reactive ion etching is described. The basic idea of this technique is to form pillar or line type patterns thin enough to be transparent to electron beams used in transmission electron microscopy. Since the entire process is conducted in the semiconductor fabrication facility, reliable samples were efficiently obtained within a short time without mechanical polishing or ion milling. High Resolution Electron Microscopy (HREM) images of SiGe and GaAs multilayer structures were obtained by this method. Using the alignment function of the e-beam lithography system, cross sectional TEM samples at specific locations of MOS transistors were obtained. The samples were thin enough to obtain HREM images of atomic level defects in the device.
Transmission Electron Microscopy Specimen Preparation of Ceramic Coatings on Ceramic Fibers
Authors: Cinibulk M. K. , Welch J. R. , Hay R. S. 
Published: April 2011

AbstractA method of preparing transmission electron microscopy (TEM) specimens of coated ceramic fibers has been developed that produces large areas containing many electron transparent fibers, due to the minimal preferential milling of the epoxy matrix. Multiple individual fibers or tows are impregnated with a high-temperature epoxy and contained to assure a high fiber-to-epoxy volume ratio. The samples are then sectioned and mechanically thinned either parallel or normal to the fiber axes using a wedge polisher on diamond lapping films to achieve a thickness of less than 5 μm. The thinned sample is then ion-milled to electron transparency in less than 30 min, giving representative specimens of the coating, fiber, and coating-fiber interface. This technique is also well suited to preparing extremely flat specimens for both light microscopy and scanning electron microscopy analysis of thin coatings.
Two-View Small-Angle Wedge Sample Preparation By Hand Tools For Transmission Electron Microscopy Of Semiconductors And Related Materials
Authors: Suder Suli , Faunce C. A. , Donnelly S. E. 
Published: April 2011

AbstractVarious small-angle wedge two-view samples have been prepared by a small-angle cleavage technique using hand tools and examined by transmission electron microscopy. Cleaved wedges from the same material are mounted both as plan-view and cross-sectional samples on the same TEM specimen grid allowing convenient examination in both views. Samples of Si3N4, Zr, Co and TiN/CN/TiN films deposited on Si, and He ion implanted Si prepared by this technique are shown to be suitable for analysis in the TEM.
Two-Dimensional Profiling of Dopants in Semiconductor Devices Using Preferential Etching/Tem Method
Authors: Kimura H. , Shimizu K. 
Published: April 2011

AbstractWe present a sample preparation technique for using transmission electron microscopy (TEM) to profile the dopant in a specified doped region of a very large scale integrated (VLSI) devices. This technique is based on preferential etching of the doped region in silicon. Because the rate at which silicon is etched depends on the dopant concentration, the dopant distribution can be inferred by observing the thickness fringe. Using two-beam approximation and information on the dependence of the etching rate on the concentration, we calculated the intensity of the transmitted electron beam and found that the results agreed well with the observed fringes. In addition, by using a focused ion beam (FIB), we could also observe the dopant distribution in a specified source region of a VLSI device.
Xtem Sample Preparation for Failure Analysis in Semiconductor Devices Using High Energy Ion Beam Thinning
Authors: Bugiel E. 
Published: April 2011

AbstractXTEM investigations are an important tool to characterize the geometry, structure and microchemical composition of semiconductor devices. Over the last 25 years, several thinning procedures have been used, based on Ar ions at about 5 kV. Common to all of them is that the thinning takes several hours, or the ion thinning has to be combined with awkward mechanical preparation steps, like dimpling.The technique described below uses Ar ions up to 15 keV and with a total ion current of up to 0.2 mA. A maximum sputtering rate of 25 μm/h for Si is reached at an incidence angle of 6°. A low energy thinning step at 3.5 keV is used at the end to reduce the amorphization and heating of the thinnest regions. The combination of this fast ion thinning with simpler mechanical steps requiring only a final lapping step, without the need for dimpling and polishing, results in a yield of nearly 100% and a preparation time of about 3h.
Correlation Functions for Nanostructures Obtained by Nucleation and Growth Kinetics
Authors: Crespo D. , Garrido V. 
Published: April 2011

ABSTRACTMost of the physical properties of systems underlying first order phase transitions, I. e. the scattering properties, can be obtained from the spatial correlation functions. For the case of nucleation and growth kinetics it is possible to obtain all the correlation functions from the particle size distribution. In this paper we obtain the spatial correlation functions corresponding to several kinetics; in particular the correlation functions corresponding to the microstructure developed in partitioning transformations are obtained.
Evolution of γ′ Precipitation Kinetics and Morphology in a Ni- 13.36 at.% Al Alloy Aged Under Compression
Authors: Prikhodko S. V. , Nielsen R. T. , Ardell A. J. 
Published: April 2011

ABSTRACTThe influence of an applied uniaxial compressive stress on the coarsening of γ′ (Ni3A1) precipitates at 640°C in a Ni-13.36 at. % Al alloy was studied experimentally. The investigation was done using cylindrical doubly-tapered monocrystalline specimens with axes of revolution parallel to [100]. At an applied load of 940 N the compressive stress varied from ∼30 to ∼130 MPa in any given specimen. Over this range of stresses the strain was primarily elastic. Dark-field transmission electron microscopy, coupled with image-analysis software, was used to characterize evolution of the γ′ precipitate morphology, and the kinetics of coarsening in (100) were investigated for aging times up to 504 h. We find, quite unexpectedly, that the relationship between the kinetics of coarsening and the applied stress is not monotonic. Instead, a maximum in the coarsening rate obtains at an intermediate stress, in the neighborhood of 55 ± 10 MPa. Theoretical work by Johnson predicts that for certain combinations of lattice and elastic-constant mismatch, an extremum of the solubility limit exists in elastically isotropic specimens aged under uniaxial stress. The theory is not sophisticated enough to enable a quantitative comparison with experimental results, but provides some rationale for our unexpected finding.
Vacancy Properties In 5d Bcc Transition Metals: Ab Initio Study At Finite Electron Temperature
Authors: Satta Alessandra , Willaimel F. , de Gironcoli Stefano 
Published: April 2011

ABSTRACTThe self-diffusion constants for the monovacancy mechanism in the 5d transition-metals with bcc structure (β-Hf, Ta and W) are investigated by first-principles pseudopotential calculations within the framework of the Local Density Functional Theory. The formation and migration energies, calculated for relaxed configurations using supercells containing 27 and 54 atomic sites, are in quite good agreement with experimental data in Ta and W, with a discrepancy lower than 10 %. Preliminary results in β-Hf using smaller supercells suggest very large relaxation energies. The effect of finite electron-temperature is shown to be quite important, and very different from one element to the other: the electron contribution to the activation entropy is negative in Ta and positive in W, reaching respectively −2 kB and 2 kB at the melting temperature. Using simple estimates for the attempt frequencies and the vibrational formation entropies, the calculated self-diffusion coefficient is in exceptional agreement with experiments in W, and clearly reproduces an accelerated diffusivity in Ta.
Evolution of γ′ Precipitate in in-713C for Long Aging Treatments
Authors: Ges A. , Fornaro O. , Palacio H. 
Published: April 2011

ABSTRACTThe strength of nickel-base superalloys hardened through precipitation is related to the volume fraction, particle size and distribution of the precipitate phase γ′: Ni3(Al,Ti). Such particles grow during the initial heat treatment and for long aging times, and it is very important to predict the kinetics growth owing to its technological application at high temperatures. In this work, we performed the analysis of the particle coarsening in IN-713C during long aging times at constant temperature (T=1223K), given an initial size, the volume fraction distribution of the γ′ precipitate phase, the evaluation of two different heat treatments through the microstructure analysis and γ′ morphology and tensile properties between 873–1123K. We found that for short aging times, t < 9×106s, the coarsening can be approximated by a linear volumetric growth as predicted by LSW theory. For a time greater than 9×106s the growth rate of γ′ precipitate shows an asymptotic behavior in both heat treatments.
The L12 to DO19 Phase Transformation In The Intermetallic Compound Fe3Ge
Authors: Chen Q. Z. , Ngan A. H. W. , Duggan B. J. 
Published: April 2011

ABSTRACTA large kinetics hysteresis is found to exist between the forward and backward reactions of the L12 ↔ DO19 transformation in Fe3Ge. The slow DO19 to L12 transformation leaves behind very stable twins and stacking fault debris. In-situ annealing experiments in the transmission electron microscope revealed that nucleation for the reverse L12 to DO19 reaction takes place efficiently at these defects.
AC Field Induced Polarization Disordering in The Ferroelectric Phase Of Modified Pzt Ceramics
Authors: Tan Q. , Viehland D. 
Published: April 2011

ABSTRACTPronounced nonlinear enhancements in dielectric responses and decreases in phase transformation temperatures were induced under moderate ac fields and high field cycling for La modified lead zirconate titanate (PZT) ceramics. Polarization disordering could be inhibited by introducing acceptor dopants into La modified PZT compositions and by DC bias field. Analysis of the frequency dispersion revealed that the field driven transformation in lower La content PZT is a field assisted activation process, while the transformation in higher La content PZT relaxors is intrinsically a thermal activated process.
Effect of Phase Transformations on Hardness of Semiconductors
Authors: Galanov B. A. , Grigor'ev O. N. , Gogotsi Y. G. 
Published: April 2011

ABSTRACTModels that describe hardness of materials do not account for stress-induced phase transformations that occur under sharp indenters. However, experimental work shows that some materials can be transformed under the indenter into new, high-pressure phases with properties that differ significantly from those of the pristine material. In particular, semiconductors (Si, Ge and other) experience Herzfeld-Mott transition (metallization). Significant volume changes can accompany these transformations. In the present paper, Tanaka's model [1] has been modified to account for reversible phase transformations under contact loading.
Strained Ion Tracks in Amorphous Solids: Origin of Plastic Deformation
Authors: Trinkaus H. , Schober H. R. 
Published: April 2011

ABSTRACTTrack formation in amorphous solids is treated in terms of viscoelastic shear stress relaxation in thermal spike regions which is followed by the freezing-in of the associated strain increment. The resulting strained tracks are considered to be the mesoscopic defects responsible for anisotropic creep and growth. A recently presented approximate quantitative approach to the problem is reviewed. In addition, a new set of constitutive equations describing the viscous flow in thermal spike regions is suggested and general solutions are discussed.
Disordering in the Ni-Al system under low dose ion-irradiation: a computer simulation study
Authors: Almazouzi A. , Alurralde M. , Spaczer M. , Victoria M. 
Published: April 2011

ABSTRACTStarting from the radiation damage cascades, as obtained using the binary collision approximation, we derive the spatial distribution of the energy deposited into the lattice by the primary knock-on atom (PKA). We follow the time evolution of the cascade core in two ordered intermetallics Ni3Al and NiAl, using the molecular dynamics (MD) method with the embedded potential and with the liquid droplet model (LDM) in which a simplified version of the heat equation is solved. Moreover, the MD was used to determine the evolution of the local structure and to identify the disordered zones. The LDM allows us, after a calibration with MD results, to estimate the dependence of the molten volume on the PKA energy up to 1 MeV. The results show good agreement with other published simulations and the available transmission electron microscopy (TEM) observation experiments.
Phase Transitions During Ion-Beam Irradiation of the Perovskite-structure Oxides
Authors: Meldrum A. , Boatner L. A. , Ewingt R. C. 
Published: April 2011

ABSTRACTSeveral perovskite-structure oxide compounds, including CaTiO3, SrTiO3, BaTiO3, KNbO3, and KTaO3 were irradiated by 800 keV Kr+ ions in order to investigate and compare their response to heavy-ion irradiation. The critical amorphization temperature Tc, above which amorphization could not be induced, was found to increase in the order SrTiO3 → CaTiO3 → BaTiO3 → KNbO3 → KTaO3. No single physical parameter explains the observed sequence, although Tc correlates well with the melting temperatures. The well-known solid state phase transformations in these materials did not have a significant effect on the dose required for amorphization. Domain boundaries were observed in the pristine samples; however, after only a low dose, the boundaries became poorly defined and, with increasing dose, eventually disappeared. Dislocation loops were observed to aggregate at the domain boundaries.