bluuebunny/crossref_metadata_2025_split huggingface dataset:
Supercritical Fluid Treatment to Improve Dielectric and Mechanical Properties of Porous ULK Thin Films
Authors: Beynet Julien , Jousseaume Vincent , Madec Alain , Rémiat Bruno , Albérola N. Dominique , Mercier Régis , Passemard Gérard 
Published: April 2011

AbstractSpin-on glass organosilicate films are promising Ultra Low-ĸ (ULK) interlevel dielectric candidates in which porosity can be created by incorporating thermally labile porogens. The as-deposited film (called the hybrid film) consists of a methylsilsesquioxane (MSQ) matrix and an organic porogen. The standard porogen removal step consists of a 450°C thermal annealing. However, it leaves polymeric residues suspected to cause an incomplete matrix crosslinking and, consequently, to be detrimental to the porous film's electrical and mechanical properties. In this work, a supercritical fluid (SCF) treatment, performed on a 200 mm tool, was added before the thermal annealing with the intent of improving the dielectric properties. Electrical and mechanical properties were greatly enhanced: the dielectric constant was reduced from 2.5 to 2.1 and the Young's modulus was increased from 2 GPa to 3 GPa. Porogen residue removal and cross-linking improvements were investigated by Fourier Transform Infrared (FTIR) spectroscopy in transmission and multiple internal reflection (MIR) mode.
Zeolite Low-k Film Properties Dependence on Nanocrystal Size
Authors: Eslava-Fernandez Salvador , Baklanov M.R. , Iacopi F. , S.H. Brongersma , Kirschhock C.E.A. , Maex K. 
Published: April 2011

AbstractSpin-on pure-silica-zeolite MFI films consist of zeolite nanocrystals embedded in a compacted silica matrix of zeolite primary nanoparticles. They appear to be promising as a low-k material due to their good mechanical properties and high microporosity, parallel to their intrinsic low k-value. Results are promising but the implementation of this material is still far away. To contribute to the implementation we present a study on the final film properties depending on the zeolite MFI nanocrystal size. Different techniques are used for the characterization: Dynamic Light Scattering, X-ray diffraction, Scanning Electron Microscopy, Nitrogen adsorption, EllipsoPorosimetry using toluene and NanoIndentation. The results show a clear dependence of the film properties on the nanocrystal size. Clearly, smaller nanocrystals provide better homogeneity, smaller pore size and higher mechanical properties. However, due to the hydrophilicity of the silica matrix lower k-values are only obtained for larger zeolite nanocrystals which provide with higher crystallinity in the films.
Topographical and chemical surface modification of porous MSQ using silylating agents with different numbers of methoxy groups
Authors: Smith Casey , Mueller Dennis , Matz Phil , Reidy Rick 
Published: April 2011

AbstractPlasma ash processes that cause surface damage in porous interlayer dielectric materials (ILDs) result in increased water absorption, permittivity, and metal intrusion. In this study, we employ mono-, di-, and tri-functional alkoxide silylation agents in supercritical CO2 to repair O2 ash damaged low-k methylsilsesquioxane (MSQ) films. Fourier transform infrared spectroscopy (FTIR) was performed using normal incidence transmission and attenuated total reflection (ATR) techniques to highlight differences in silylation efficiency based on agent functionality. Contact angle measurements reveal a significant change in hydrophobicity after functionalization of the O2 ashed samples with multifunctional agents. Atomic force microscopy (AFM) was utilized to determine changes in surface topography after ashing and repair.
Effects of Dielectric Thermal Expansion and Elastic Modulus on the Stress and Deformation Fields in Copper Interconnects
Authors: Shen Yu-Lin 
Published: April 2011

AbstractThis study aims at assessing the role played by the coefficient of thermal expansion (CTE) and elastic modulus of low-k dielectric, in affecting the stress and deformation fields in copper interconnects. Parametric finite element analyses are conducted, varying one parameter at a time, for gaining fundamental understanding of the effect of individual properties. The analyses are based on a three dimensional model containing two levels of metal lines connected by a via. It is found that both the high CTE and low modulus values of the polymer-based dielectric contribute to the evolution of stress/strain fields in the metal structure. The low-k CTE plays a more significant role. Within certain limits, decreasing the low-k CTE and/or increasing the low-k modulus can help alleviate the plastic deformation, and thus the propensity of damage initiation, in the metal. Reducing the low-k CTE will be a more efficient and safer approach.
Copper Electroplating on Zero-Thickness ALD Platinum for Nanoscale Computer Chip Interconnects
Authors: Kaloyeros Alain , Zhu Yu , Dunn Kathleen , Mayti Richard , Miller Christopher , Breslin Matthew 
Published: April 2011

AbstractUltra-thin platinum (Pt) films grown by atomic layer deposition (ALD) have been investigated as an alternative to conventional physical vapor deposited (PVD) Cu as seed layer for copper (Cu) electroplating. The wetting angles between the electrolyte and both Pt and Cu seed layers were analyzed using sessile-drop contact-angle analysis prior to plating. Both constant current and pulse reverse current (PRC) were applied to electroplate Cu on both types of blanket seed layers. Scanning electron microscope (SEM) revealed that Cu nucleation density on ALD Pt is lower than on its PVD Cu counterpart, after 30 seconds plating using PRC. Nevertheless, Cu nuclei were observed after only 1.0 minute plating on ALD Pt surfaces, and continuous Cu films were achieved at longer plating times. To fill trench structures coated with ALD Pt/TaN, PRC was applied using the same organic-additive-free electrolyte. Initial results suggest that these seed layers were adequate for ECD fill of trenches with 200 nm feature size and aspect ratio 7:1. The composition and microstructure of the Cu films were analyzed by Auger electron spectroscopy (AES), X-ray diffraction (XRD), and cross-sectional transmission electron microscopy (TEM). Thermal stability of the Cu/Pt system was examined by annealing in forming gas at 450°C for 1 hour and subsequent analysis by XRD and TEM.
Scaling of Statistical and Physical Electromigration Characteristics in Cu Interconnects
Authors: Gall Martin , Hauschildt Meike , Justison Patrick , Ramakrishna Koneru , Hernandez Richard , Herrick Matthew , Michaelson Lynne , Kawasaki Hisao 
Published: April 2011

AbstractEven after the successful introduction of Cu-based metallization, the electromigration (EM) failure risk has remained one of the important reliability concerns for most advanced process technologies. Ever increasing operating current densities and the introduction of low-k materials in the backend process scheme are some of the issues that threaten reliable, long-term operation at elevated temperatures. The main factors requiring attention and careful control are the activation energy related to the dominating diffusion mechanism, the resulting median lifetimes, and the lognormal standard deviation of experimentally acquired failure time distributions. Whereas the origin of the EM activation energy and the behavior of median lifetimes with continuing device scaling are relatively well understood, detailed models explaining the origin and scaling behavior of the lognormal standard deviation are scarce. The statistical behavior of EM-induced void sizes and resulting lifetime distributions appear to be explainable by geometrical variations of the void shapes and the consideration of kinetic aspects of the EM process. Using these models, expected lifetime distributions for future technology nodes can be simulated from current, experimentally obtained void size and lifetime distributions. These simulations have to include geometrical factors of the EM test structures and actual, on-chip interconnects, as well as kinetic aspects of the mass transport process, such as differences in interface diffusivity between the lines. By extrapolating the expected lifetime distributions for future technology nodes from current EM data, it is possible to predict when insertion of new process schemes, such as Cu-alloys and/or metallic coating of the Cu/passivation interface is required.
In-situ Observation of the Formation and Growth of Twin in the Copper Electrodeposits for Ultra Large Scale Integration
Authors: Han Heung Nam , Lee Hyo-Jong , Kim Do Hyun , Lee Ui-hyoung , Cha Pil-Ryung , Oh Kyu Hwan 
Published: April 2011

AbstractDuring the self-annealing in the copper electrodeposits for the copper metallization, an in-situ observation of grain growth of the copper at room temperature was performed by using EBSD (electron backscatter diffraction). The thin film structure of the copper electrodeposits after annealing was columnar. New twin was initiated at the front surface of growing twin and grew along the normal direction of the twin boundary between the new and parent twins. It was confirmed that the annealing twin in the copper electrodeposits during the self-annealing have an {111} growth front surface.
Chemical Bonding, Permittivity and Elastic Properties in Locally Modified Organosilicate Glass
Authors: Zschech Ehrenfried , Stegmann Heiko , Hoffmann Patrick , Schmeisser Dieter , Potapov Pavel , Engelmann Hans-Juergen , Chumakov Dmytro , Geisler Holm 
Published: April 2011

AbstractChanging local electronic polarizability and chemical bonding in OSG in such a way that the effective permittivity - and consequently the electrical performance of the Cu/low-k structure - deteriorates only slightly and that adhesion and stiffness are improved significantly is an extremely challenging task [1], [2]. As the interconnect line spacings continue to shrink, optimization of the electrical and mechanical properties of the ILD material becomes increasingly important for Cu/low-k integration since the effect of thin regions that have been modified by special treatments on the effective material properties, e. g. keff, increases. Composition and chemical bonding, changed by plasma or beam treatments, effect the materials properties significantly. Plasma processes for resist stripping, trench etching and post-etch cleaning remove C and H containing molecular groups from the near-surface layer of OSG. Electron-beam interaction with OSG changes the chemical bonding in the low-k material. In this paper, the effect of chemical bonding on permittivity and elastic modulus is studied. Compositional analysis and chemical bonding characterization of structured ILD films with nanometer resolution is done with electron energy loss spectroscopy (EELS). The fine structure near the C-K electron energy loss edge, allows to differentiate between C-H, C-C, and C-O bonds, and consequently, between individual low-k materials and their modifications. Dielectric permittivity changes are studied based on VEELS (valence EELS) measurements and subsequent Kramers-Kronig analysis. The elastic modulus is determined with atomic force microscopy (AFM) in force modulation (FM) mode. Nanoindentation was applied as a complementary technique to obtain reference data.
Bio-Hybrid Materials for Immunoassay-Based Sensing
Authors: Fang Jonathan , Lan Esther H. , Zhou Jing C. , Dunn Bruce 
Published: April 2011

AbstractThe process of encapsulating antibodies in sol-gel was used for sensing various hormones, specifically cortisol, insulin, and C-peptide. A sol-gel optical biosensor for cortisol has been developed for monitoring of crew health on-orbit during space missions. Our studies involving silica sol-gel materials with competitive immunoassays demonstrated linear calibration for cortisol in the range of 2-60 μg/dL, which covers the physiological range of cortisol blood concentration for an adult (2-28 μg/dL). The method of standard additions was used to analyze human serum samples sent to us from a NASA laboratory. Our sol-gel immunosensor values were typically within 20% of the values obtained by NASA-JSC using traditional immuno-binding techniques, with some values having less than a 5% error. Initial results are presented for sensing the hormones insulin and C-peptide.
Stem Cell Impregnated Carbon Nanofibers/Nanotubes for Healing Damaged Neural Tissue
Authors: Lee Jong Eun , Khang Dongwoo , Kim Yong Eul , Webster Thomas Jay 
Published: April 2011

AbstractCarbon nanotubes and nanofibers are intriguing materials for medical applications due to their unique mechanical, electrical, and surface properties which have been shown to enhance neural cell functions compared to other central nervous system implants such as silicon. The objective of this study was to determine if stem cells can be combined with carbon nanofibers in the treatment of stroke damaged neural tissue in rats. Preliminary results demonstrate the ability of stem cells to differentiate into neurons when injected with carbon nanofibers into stroke damaged neural tissue. Moreover, little scar tissue formation was observed. Although preliminary, such results indicate promise for the use of carbon nanofibers as novel stem cell delivery vehicles for neural damage.
Newly Developed Fe-Fe2O3/Polyoxocarbosilane Core-Shell Nanocomposite Prepared by Laser Pyrolysis: Characterization and Sensing Properties
Authors: Morjan Ion , Pola Joseph , Alexandrescu Rodica , Dumitrache Florian , Tomescu Adelina , Birjega Ruxandra , Gavrila-Florescu Lavinia , Soare Iuliana , Voicu Ion , Galikova Anna , Ciupina Victor , Bastl Zdenek 
Published: April 2011

AbstractNanocomposites of iron /iron oxide/ polyoxocarbosilane were prepared by the IR co-pyrolysis of Fe(CO)5 and HMDSO. Their morphologies, chemical content and thermal behavior were studied by different analytical techniques. For examining the sensing capabilities of the low-polymer content nanocomposite thick films, the variation of the electrical resistance to CO and CH4 gases was tested. A promising behavior as concerning the sensitivity and the selectivity was found.
Modulation of Electronic Properties of Single Wall Carbon Nanotubes by the Presence of an Ionic Shell
Authors: Dobrokhotov Vladimir , Berven Chris 
Published: April 2011

AbstractWe report the change to the band structure of two types of carbon nanotubes due to the presence of an isolated, non-conducting, uniformly charged shell held at a fixed distance above their surfaces. We find that, depending on the chirality of the nanotube, the strain on the lattice causes the dispersion relationships to change. This change can result in a modification of the band structure which can induce a metal-semiconductor transition. We consider these effects as a possible mechanism for heavy-metal ion sensing by functionalized carbon-nanotubes.
Synthesis, Characterisation of WO3 Nanofibers and their Application in Chemical Gas Sensing
Authors: Piperno Silvia , Passacantando Maurizio , Lozzi Luca , Cantalini Carlo , Phani Ratna A. , Santucci Sandro 
Published: April 2011

AbstractWO3 nanofibers have been produced by a simple method as electrospinnig. This is a process by which polymer nanofibers (with submicron scale diameters) can be formed when a droplet of viscoelastic polymer solution is subjected to high voltage electrostatic field. Polymer PMMA and WCl6 solution mixtures were used as precursors. The nanofiber were characterized morphologically and chemically by XPS, SEM, and XRD measurements and it was found the formation of mixed WOx/PMMA nanowires at room temperature that evolve after annealing at 300°C towards pure WO3 nanofibers as evidenced by XPS measurements. After the characterization the nanofibers have been deposited on the sensor devices to check their gas sensing properties. They show a semiconductor-like behaviour when they are heated and wide variation of the electrical resistance when they are exposure to NO2 gas.
A1Bi3C6 Thin Films as NO Sensors
Authors: Khlyap Halyna , Bilozertseva Violetta , Dyakonenko Nina , Gaman Dmitrii , Mamalui Andrey , Khlyap Hayna M. 
Published: April 2011

AbstractThe paper reports experimental data on growth, morphology, NO sensitivity and electrophysical properties of A1Bi3C6 thin films obtained by means of simple vacuum technology. The investigated samples were condensed onto the glass substrates under deposition rate 0.1-0.5 nm/s at T = 300 K and vacuum level P = 10-3 Pa. AFM investigations of the film surface before and after interaction with aggressive environment demonstrated sufficient sensitivity of the film relief to the aggressive component. Room-temperature electric field-induced characteristics were investigated for metal-semiconductor (MS) Cr/NaBiTe2 structures.
Platform based Detection Technologies from Micro scale to Nanoscale
Authors: Kundura Vindhya , Padigi Sudhaprasanna Kumar , Prasad Shalini 
Published: April 2011

AbstractRapid, multiplexed, high throughput detection of proteins is essential for the development of protein biomarkers as sensors. Electrical alignment and detection is a non-invasive, label free technique for rapid identification of bimolecular. We present here a micro fabricated platform based detector for rapidly identifying protein biomarkers present in atherosclerotic plaque for rapid clinical diagnosis of arterial obstruction. This is achieved by electrical assembly of polystyrene beads functionalized with specific antibody receptors (anti-C-reactive protein) .The electrical assembly is achieved using electrophoresis. The polystyrene “bridge” micro structure formed due to electrical assembly aids in the amplification of the antibody-antigen binding event. Antigen (C-reactive protein) at nanogram / ml concentration was detected when binding of the antigen resulted in an amplification of the electrical signal that was measured from the base microelectrode platform. This technique is a demonstration of the application of microscale technology (electrodes) in nanoscale (protein) electrical detection.
Control of Interfacial Structure and Electrical Properties in MBE Grown Single Crystalline SrTiO3 Gate Dielectrics on Si(100)
Authors: Norga Gerd , Marchiori Chiara , Rossel Christophe , Guiller Alexandre , Locquet Jean-Pierre , Siegwart Heinz , Caimi Daniele , Fompeyrine Jean , Seo J. W. , Dieker Christel 
Published: April 2011

AbstractIn this paper, we point out the critical role of oxygen stoichiometry in the solid state epitaxy process used for obtaining 5 A EOT in SrTiO3 gate dielectrics on Si. Incomplete oxygenation of the TiO2 fraction of the amorphous SrO.TiO2 film enhances the inherent tendency of TiO2 to react with Si to yield TiSi2 and SiO2. O2 excess is needed to obtain a crystalline interface after UHV crystallization. The solid state epitaxy process results in heavily oxygen deficient films, whose insulating properties can be recovered by an atomic oxygen treatment.
Correlation of Phase Segregation and Electrical Properties of Low-Power MOSFETs with Hf-based Silicate Gate Dielectric Layers and TaN Metal Gates
Authors: Petry Jasmine , Rittersma Chris , Vellianitis Georgios , Cosnier Vincent , Conard Thierry , Deweerd Wim , Van Berkum Jan G.M. 
Published: April 2011

AbstractThe need for nitridation of Hf silicate is controversial. On one hand, it has not been proven that the nitridation is mandatory to have working devices and on the other hand, it is known to increase the charge density. In this paper, we present a detailed comprehensive study of the role and the need for nitridation of Hf-based silicates deposited by Atomic Layer Deposition (ALD). The results are based on a correlation of Fourier-Transformed Infrared Spectroscopy (FT-IR), X-ray Photoelectron Spectroscopy (XPS), High-resolution Transmission Electron Microscopy (HR-TEM) and electrical measurements (gate leakage and mobility).It was observed that the phase segregation in gate dielectrics is not detrimental for the gate leakage density at room temperature. However, the leakage current is significantly increased at higher temperature. The incorporation of nitrogen was either done by NH3 anneal (at 800C) or by Decoupled Plasma Nitridation (DPN – 25.9kJ). While the DPN or NH3 anneal prevent phase segregation for 50% Hf silicate, only the NH3 anneal helps prevent the phase segregation of Hf-rich silicate. Furthermore, the NH3 anneal increases the interfacial thickness, which produces a very low gate leakage with only 10% loss in mobility at high field. Interestingly, DPN followed by O2 anneal leads to an advantageous phase segregation of the Hf-rich silicate by transforming the silicate in a HfO2/SiO2-like stack.As a conclusion, not only the phase segregation of the silicate does not always lead to shorted devices, but it can be beneficial in terms of mobility. However, the phase segregation seems to be responsible for an enlarged trap-assisted conduction mechanism at high temperature. But even if the 50% Hf silicates non-nitrided leads to working devices, the incorporation of nitrogen in the stack improves the Jg/CET trends and is therefore beneficial.
In situ ATR - FTIR spectroscopy of Hf(IV) tert butoxide adsorption on Si and Ge
Authors: Dubey Shilpa , Li Keijing , Bhandari Harish , Hu Zheng , Turner C. Heath , Klein Tonya M. 
Published: April 2011

AbstractHafnium oxide ultra thin films on Si (100) are being developed to replace thermally grown SiO2 gates in CMOS devices. In this work, a specially designed Attenuated Total Reflectance - Fourier Transform Infra Red Spectroscopy (ATR-FTIR) reaction cell has been developed to observe chemisorption of hafnium (IV) t-butoxide onto a Si and Ge ATR crystal heated up to 250°C and under 1 torr of vacuum to observe the initial reaction pathways and species on the substrate surface in real time and under typical process conditions. Chemisorption spectra were compared to spectra of the liquid precursor and to spectra generated by density functional theory (DFT) calculations of liquid, monodentate and bidentate absorbed precursor. An asymmetric stretching mode located at ~1017 cm-1 present in the chemisorbed spectra but not in the liquid spectra indicates that the adsorbed hafnium containing group is prevalent as a bidentate ligand according to calculations. Surface concentration of the chemisorbed species was dependant on the substrate temperature and precursor partial pressure allowing for determination of heats of adsorption which was 26.5 kJ/mol on Si.
Characterization of HfO2/Si Exposed to Water Vapor at Room Temperature
Authors: Driemeier Carlos , Martinazzi Elizandra , Baumvol Israel J. R. , Gusev Evgeni 
Published: April 2011

AbstractHfO2-based materials are the leading candidates to replace SiO2 as the gate dielectric in Si-based metal-oxide-semiconductor filed-effect transistors. The ubiquitous presence of water vapor in the environments to which the dielectric films are exposed (e.g. in environmental air) leads to questions about how water could affect the properties of the dielectric/Si structures. In order to investigate this topic, HfO2/SiO2/Si(001) thin film structures were exposed at room temperature to water vapor isotopically enriched in 2H and 18O followed by quantification and profiling of these nuclides by nuclear reaction analysis. We showed i) the formation of strongly bonded hydroxyls at the HfO2 surface; ii) room temperature migration of oxygen and water-derived oxygenous species through the HfO2 films, indicating that HfO2 is a weak diffusion barrier for these oxidizing species; iii) hydrogenous, water-derived species attachment to the SiO2 interlayer, resulting in detrimental hydrogenous defects therein. Consequences of these results to HfO2-based metal-oxide-semiconductor devices are discussed.