bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling of Water Uptake and Salt Leaching in Bituminized Radioactive Waste: Comparison Between Numerical, Analytical and Experimental Results
Authors: Sercombe J. , Adenot F. , Tiffreau C. , Gwinner B. , Felines I. 
Published: April 2011

ABSTRACTIn this paper, a simplified model which allows the derivation of analytical relations aiming at describing the diffusion-dissolution-swelling processes taking place in bituminized waste exposed to water or salt solutions is presented. The analytical solutions render the comparison with experimental data and tendencies straightforward. The validity of the simplified approach is demonstrated by comparing analytical and numerical solutions with experimental data.
Static Dissolution of α-doped UO2 in Boom Clay Conditions: Preliminary Results
Authors: Cachoir C. , Lemmens K. 
Published: April 2011

ABSTRACTTo support the performance assessment (PA) calculations for the possible final disposal of spent fuel in the Boom Clay, leach experiments are performed with α-doped UO2 in clay media, simulating various near field ages. The experiments allow to measure the dissolution rate of the UO2 and to determine the assumed relationship between dissolution rate and α-activity. Tests are performed at six different α-activities, simulating various fuel ages, at 25–30°C, for durations ranging from 90 to 720 days, in a glove box with Ar/0.4%CO2 atmosphere. The solutions and solids are analyzed for U isotopes and 238Pu by radiochemical measurement and by ICP-MS. The dissolution rates of the α-doped UO2 are presented for different durations. The resulting corrosion rate is around 300 μgU.m−2.d−1. This is up to 100 times higher than found for similar conditions in the literature. In the presence of clay, there appears to be no correlation between the α-activity and the corrosion rate of the α-doped UO2.
The Effect of Cellulose Degradation Products on the Solubility and Sorption of Pu and Am in Alkaline-Plume-Affected and in Unaffected Boom Clay
Authors: Rorif F. , Valcke E. , Glaus M. A. 
Published: April 2011

ABSTRACTThe potential effect of water-soluble degradation products (DPs) formed from cellulose-containing cemented radioactive waste on the behaviour of Pu(IV) and Am(III) in Alkaline-Plume-Affected (APA) and in unaffected Boom clay was assessed. After solubility measurements in APA Real Clay Water, sorption experiments of Pu(IV) and Am(III) onto APA Boom clay were performed in the presence or not of DPs or pure α-isosaccharinic acid (α-ISA). Moreover, the sorption of α-ISA onto the unaffected clay was studied.
Modelling of Pu Sorption onto the Surface of Goethite and Magnetite as Steel Corrosion Products
Authors: Duro Lara , Missana Tiziana , Ripoll Sonia , Grivé Mireia , Bruno Jordi 
Published: April 2011

ABSTRACTWe have studied the surface interaction between tetravalent plutonium and two different steel corrosion products: magnetite, which is the final product of the anoxic corrosion of steel, and goethite, which exemplifies a further oxidation of the steel surface due to the presence of active oxidants in the system. The pH of the experiments has been varied from 2 to 10 and the ionic strength from 0.001 to 0.1 M NaClO4. All the sorption experiments were carried out under N2 atmosphere. No significant effect of ionic strength was observed under the conditions studied.The pHpcz of the solids (7.78 for goethite and 6.95 for magnetite) was determined by modelling potentiometric titration data.The results of the experiments show that the sorption edge of plutonium occurs between pH 3 and 4 when using goethite as a sorbing surface and between pH 4 and 5 when magnetite is used.We have modelled the sorption data by using a simple surface complexation approach with no electrostatic term. The model used involves a reduction process of Pu(IV) to Pu(III) in the presence of magnetite, which can be explained by the interaction of the actinide with the ferrous iron present in the solid. In the case of the experiments conducted with goethite, this reduction process is not possible and, therefore, in the model we have included the sorption of tetravalent Pu.
The Second Safety Assessment and Feasibility Interim Report (SAFIR 2 Report) on HLW Disposal in Boom Clay: Overview of the Belgian Programme
Authors: Gens Robert , Lalieux Philippe , Preter Peter De , Dierckx Ann , Bel Johan , Boyazis Jean-Paul , Cool Wim 
Published: April 2011

ABSTRACTONDRAF/NIRAS – the Belgian radioactive waste management agency – has published in 2001 the SAFIR 2 report on request of the authorities. The SAFIR 2 report is to be considered as a state-of-the art report and not as a complete safety case. This report gives an overview of the Belgian R&D program related to the geological disposal of HLW and ILW for the period 1990–2000 in the Boom Clay (reference host rock). The three main outcomes of the SAFIR 2 report on which this paper will be more specifically focusing, are the following (including results reported after 2000): long-term safety functions, confirmation of the role of the Boom Clay formation as the main barrier and identification of practical difficulties with respect to technical feasibility (repository design).
Study of 3-MeV electron irradiation damage in amorphous silicon with TRMC
Authors: Klaver A. , Warman J.M. , Haas M.P. de , Metselaar J.W. , Swaaij R.A.C.M.M. van 
Published: April 2011

ABSTRACTThe effects of 3-MeV electron irradiation on a-Si:H have been studied using Time-Resolved Microwave Conductivity (TRMC). A Van der Graaff electron accelerator is used to generate the probe-beam pulses for the TRMC experiment as well as for the in-situ irradiation of the samples for the degradation of the material. Using several probe-beam pulse doses, TRMC transients were obtained on samples that have been subjected to various radiation fluences. These transients were later analyzed using a simple model based on the Shockley-Read-Hall capture and emission processes. Using these simulations we deduce a relationship between the radiation fluence and the defect density in the material.
Amorphous Si1-YGeY:H, F films obtained by Low Frequency PECVD for uncooled microbolometers
Authors: Ambrosio R. , Torres A. , Kosarev A. , Abramov A. S. , Heredia A. , Landa M. , Garcia M. 
Published: April 2011

ABSTRACTIn this work, we report the composition, optical, and electrical properties of a- Si1-YGeY: H, F films to be used as sensing layer in uncooled microbolometers. The a-Si1-YGeY films where Y is Ge content in solid phase were deposited by low frequency PECVD from SiH4 and GeF4 feed gases, and H2 and Ar were used for dilution. The film composition, IR transmission and temperature dependence of conductivity were measured. The reduction of conductivity activation energy from 0.86 eV to 0.39 eV and the increase of room temperature conductivity from 1x10−9 to 2.1×10−3 Ohm−1cm−1 were observed with the change of Y from 0 (Si) to 1(Ge). These results demonstrate this material to be a good candidate as a sensing material in uncooled micro-bolometers, due to its high absorption in the range of λ = 10-13 μm, its relatively high activation energy, Ea=0.4 eV, consequently, a high temperature coefficient of resistance (TCR), and moderate resistivity at room temperature.
High Current Density in m c-Si PECVD Diodes for Low Temperature Applications
Authors: Beck Patricia A. , Nickel Janice H. , Hartwell Peter G. 
Published: April 2011

ABSTRACTThe development of microcrystalline diodes grown at low temperature by PECVD techniques is reported. Current densities near 200 A/cm2 at + 2 V, and rectification ratios on the order of 105 at +/- 1V and 107at +/- 2V were obtained. The reverse currents were in the nano-ampere range. Correlations between deposition conditions and film quality are presented. The effects of mesa formation and subsequent treatments designed to reduce process damage are discussed: annealing conditions yield an increase in forward current, and a decrease in reverse current. Fabrication conditions are compatible with applications requiring low temperature processes (e. g., multi-layer structures, molecular layers, or plastic substrates and coatings).
Interpretation of Transient Photocurrents in Coplanar and Sandwich PIN Microcrystalline Silicon Structures
Authors: Reynolds Steve , Smirnov Vladimir , Main Charlie , Finger Friedhelm , Carius Reinhard 
Published: April 2011

ABSTRACTWe report on the use of coplanar transient photoconductivity and post-transit time-of-flight spectroscopy techniques in the study of carrier transport in microcrystalline silicon films prepared over a range of crystallinities. Coplanar samples are susceptible to post-deposition oxidation and reversible adsorption of atmospheric gases, which may alter the apparent density of states. Coplanar measurements suggest lower deep defect densities in more highly crystalline films, but this is due at least in part to an increased occupancy of these states. A comparison of results obtained using both techniques suggests anisotropic transport, with reduced band tailing (greater structural order) along the direction of film growth, a larger defect concentration around the column boundaries, and a higher defect density within the amorphous tissue than in optimised single-component amorphous silicon films.
Metastability in Undoped Microcrystalline Silicon Thin Films Deposited by HWCVD
Authors: Persheyev S.K. , O'Neill K.A. , Anthony S. , Rose M.J. , Smirnov V. , Reynolds S. 
Published: April 2011

ABSTRACTFilms deposited by the Hot Wire CVD method were studied by means of dark conductivity, FTIR, Hydrogen Evolution, SEM and AFM surface characterization. Three types of metastability were observed: a) long term irreversible degradation due to oxidization processes on the film surface, b) reversible degradation determined by uncontrolled water adsorption, c) fast field switching effect in the film bulk.Oxygen and hydrogen content and its bonding configurations have been analyzed by hydrogen evolution and infrared spectroscopy methods on the films deposited on glass substrates and silicon wafers subsequently. It has been found that metastable processes close to the film surface are stronger than in the bulk. The switching effect is the fast increase of charge carrier density observed on bottom chromium contacts under a condition of air admittance. We propose this effect is associated with morphology changes during film growth and electrical field induced by adsorbed atmospheric components on the film surface.
External rf substrate biasing during a-Si:H film growth using the expanding thermal plasma technique
Authors: Smets A.H.M. , Kessels W.M.M. , Sanden M.C.M. van de 
Published: April 2011

ABSTRACTThe interchangeability of ion bombardment and deposition temperature during a-Si:H film growth at high deposition rates (10-42 Å/s) by means of the expanding thermal plasma has been studied. The ion bombardment is generated by applying an external rf bias voltage on the substrate. It is shown that the opto-electronic performance of the a-Si:H films improves considerably when a moderate rf substrate bias voltage (∼20-60 V) is applied, i.e. the photo response increases two orders of magnitude up to 106. Furthermore, it is also revealed that the additional energy supplied to the growth surface by the ion bombardment, makes a reduction of the deposition temperature by ∼100 °C possible, while preserving good material properties. On the basis of the results obtained, three effects caused by the rf substrate bias can be distinguished: creation of an additional growth flux, a reduction of the void incorporation, and an increase in the vacancy density.
Growth and Characterization of Poly-SiGe Prepared by Reactive Thermal CVD
Authors: Zhang Jianjun , Shimizu Kousaku , Hanna Jun-ichi 
Published: April 2011

ABSTRACTWe have prepared poly-Si1-xGex thin films with different germanium contents (Ge=5%∼40%) by reactive thermal CVD. In this study, the Ge content was controlled by varying the source gases GeF4 flow rate at a fixed Si2H6 flow rate. The effects of GeF4 flow rate on growth rate, film crystallinity, and electrical properties were investigated. The films were always polycrystalline when GeF4 was introduced even in a small amount, while only amorphous film deposited without GeF4. With an increase in GeF4 flow rate, Ge content and conductivity of the films increased and its activation energy decreased. When GeF4 flow rate over a certain value, the growth rate decrease and finally no film could be deposited. These behaviors are discussed in relation with a role of GeF4 for the crystal growth at a low temperature.
Solid Phase Epitaxy process integration on 50-nm PMOS devices: Effects of defects on chemical and electrical characteristics of ultra shallow junctions
Authors: Farhane R. El , Laviron C. , Cristiano F. , Cherkashin N. , Morin P. , Juhel M. , Stolk P. , Arnaud F. , Pouydebasque A. , Wacquant F. , Lenoble D. , Halimaoui A. 
Published: April 2011

ABSTRACTWe demonstrate in this paper the viability of an ultra-low thermal budget CMOS process enabling the formation of ultra shallow junctions with competitive transistor characteristics. In particular, we demonstrate in this work the influence of defects on chemical and electrical results. It is shown that the use of self-amorphizing implantation with BF2for Source/Drain, reduces the junction leakage by two decades.
Applications of Ni-based silicides to 45 nm CMOS and Beyond
Authors: Kittl Jorge A. , Lauwers Anne , Chamirian Oxana , Pawlak Malgorzata A. , Van Dal Mark , Akheyar Amal , Potter Muriel De , Kottantharayil Anil , Pourtois Geoffrey , Lindsay Richard , Maex Karen 
Published: April 2011

ABSTRACTThis paper presents an overview of Ni-alloy (Ni, Ni-Pt and Ni-Ta) silicide development for the 45 nm node and beyond, including applications to self-aligned silicide (SALICIDE) processes, reaction with SiGe and strained Si on SiGe, and applications to fully silicided (FUSI) gates. Key SALICIDE issues addressed include the use of spike or low temperature rapid thermal processes (RTP) to control silicidation and junction leakage on small features, factors affecting the formation of epitaxial pyramidal NiSi2 grains, and NiSi thermal stability and agglomeration kinetics. Alloying with Pt or Ta is shown to improve thermal stability of NiSi films, although with quite different behaviors. While Pt is incorporated predominantly in solution in NiSi, Ta segregates to the surface of the films. Ni-Pt alloy silicides were also found to achieve low sheet resistance on narrow gates, low contact resistivity and low junction leakage, making them attractive for CMOS applications. For the Ni/SiGe reaction, a narrower RTP process window for low sheet resistance and a lower activation energy for agglomeration were observed when compared to the Ni/Si reaction. The lower thermal stability was correlated to Ge segregation from the Ni(SiGe) films. The Ni/doped poly-Si reaction was studied for FUSI gate applications, showing a retardation of the silicidation kinetics for high B doses and a large pile- up of dopants (for As, B or P) at the NiSi/SiO2 interface due to dopant snowplow during silicidation. The work function (WF) of NiSi was observed to shift with the addition of dopants, effect attributed to modifications of the interface dipole by the pile-up of dopants. No significant degradation was observed when comparing gate oxide breakdown statistics for Ni FUSI to conventional poly-Si gates. The process window for a FUSI gate-last process (performed after S/D Ni silicidation) was evaluated showing a potential integration problem due to possible degradation of the S/D silicide during the FUSI gate reaction.
Vibrational Spectra of Nitrogen-Oxygen Defects in Nitrogen Doped Silicon using Density Functional Theory
Authors: Karoui F. Sahtout , Karoui A. , Inoue N. , Rozgonyi G. A. 
Published: April 2011

ABSTRACTThe vibrational spectra of N-pairs and nitrogen-vacancy-oxygen defects in nitrogen doped Czochralski silicon have been investigated using density functional theory calculations. We found that 771 cm−1 and 967 cm−1 lines measured by FTIR are fingerprints for N-pairs in interstitial position. These confirm that nitrogen atoms are paired and bonded to Si atoms. Calculated local vibration modes of N2On complexes provide the best matching with observed FTIR frequency of N-O complexes. Nonetheless, VmN2On (m,n =1,2) can develop during crystal cooling or wafer processing, as revealed by local vibrational modes falling around, 806 and 815 cm−1 FTIR frequencies.
Processing damage and electrical performance of porous dielectrics in narrow spaced interconnects
Authors: Iacopi F. , Travaly Y. , Stucchi M. , Struyf H. , Peeters S. , Jonckheere R. , Leunissen L.H.A. , Tökei Zs. , Sutcliffe V. , Richard O. , Hove M.Van , Maex K. 
Published: April 2011

AbstractThe damage induced in the low-k material upon exposure to dry etch and ash plasmas is a point of major concern in terms of preservation of the dielectric properties. There is urgent need to assess, classify and quantify the extent of such damage to allow the optimization of patterning processes and conditions. Meander-fork structures with spacings between 250nm and 70nm are used in this study as vehicle to compare trends in electrical performance for different dielectrics: SiO2 and two SiOC:H low-k materials with pristine k values of 3.0 and 2.6. Here we demonstrate that the ‘electrical equivalent damage’ model is a valid and precise methodology for assessing dielectric damage upon processing from interline capacitance evaluation. This analysis allows to distinguish between bulk and sidewall modification and to quantify the extent of damage. Moreover, it provides an interpretation for the degradation of leakage current and breakdown field of the interline dielectric, revealing different trends whether due to only sidewall or total damage.
Novel Epoxy Siloxane Polymer as Low-K Dielectric
Authors: Wang Pei-I , Juneja Jasbir S. , Murarka Shyam , Lu Toh –Ming , Ghoshal Ram , Ghoshal Rajat 
Published: April 2011

AbstractThis paper introduces a low-k dielectric material, a novel epoxy siloxane polymer, made by Polyset Co. Inc, which has promising properties. The polymer was spin-deposited, and thickness and optical properties were measured using variable-angle spectroscopic ellipsometry (VASE). Fourier transform infrared (FTIR) spectra of as deposited and cured polymers showed that the polymer is fully cured at 165 °C. The low curing temperature of the polymer lowers stress in back-end-of-line (BEOL) stack and thus improves the reliability. The polymer is thermally stable up to 400 °C. The polymer has Young's modulus of ∼5 GPa and hardness of greater than 0.4 GPa. After multiple stress cycles up to 300 °C, the residual stress in the polymer at room temperature is less than 60 Mpa. The polymer has good adhesion with semiconductor and dielectrics such as Si, SiC, and SiO2, metals such as Al, Cu, Co, and W, and barrier materials such as TaN. The bulk dielectric constant of the polymer is 2.4 - 2.7. The leakage current density in the polymer at the applied electrical field of 1 MV/cm is in 10−9 A/cm2 range and the breakdown field of the polymer is ranging from 5 to 7 MV/cm. The polymer when subjected to bias-temperature stress (BTS) conditions of 150 °C and 0.5 MV/cm shows no C-V shift for up to 100 min indicating that the polymer resists Copper diffusion. The current density under stress conditions of 150 °C and 0.5 MV/cm was less than 10−9 A/cm2 for up to 7 hrs.
Reliability of Dielectric Barrier Films in Copper Damascene Applications
Authors: Lee Albert S. , Lakshmanan Annamalai , Rajagopalan Nagarajan , Cui Zhenjiang , Le Maggie , Xia Li Qun , Kim Bok Heon , M'Saad Hichem 
Published: April 2011

AbstractThe film properties of two PECVD deposited dielectric copper barrier films have been optimized to improve BEOL device reliability in terms of electromigration. Two critical aspects that affect electromigration are the dielectric barrier film hermeticity and adhesion to copper. We use a method to quantify the barrier film hermeticity and have optimized the hermeticity of the BLOκ™ low-κ dielectric barrier film to be similar to that of silicon nitride. By using FT-IR we find that the film porosity has a much stronger effect than the film stoichiometry on hermeticity. In addition, the interfaces between Damascene Nitride™ with copper, as well as BLOκ with copper have been engineered to improve the interfacial adhesion energy to >10 J/m2 for both Damascene Nitride and BLOκ.
Effect of mass transport along interfaces and grain boundaries on copper interconnect degradation
Authors: Zschech Ehrenfried , Meyer Moritz A. , Langer Eckhard 
Published: April 2011

AbstractIn-situSEM electromigration studies were performed at fully embedded via/line interconnect structures to visualize the time-dependent void evolution in inlaid copper interconnects. Void formation, growth and movement, and consequently interconnect degradation, depend on both interface bonding and copper microstructure. Two phases are distinguished for the electromigration-induced interconnect degradation process: In the first phase, agglomerations of vacancies and voids are formed at interfaces and grain boundaries, and voids move along weak interfaces. In the second phase of the degradation process, they merge into a larger void which subsequently grows into the via and eventually causes the interconnect failure. Void movement along the copper line and void growth in the via are discontinuous processes, whereas their step-like behavior is caused by the copper microstructure. Directed mass transport along inner surfaces depends strongly on the crystallographic orientation of the copper grains. Electromigration lifetime can be drastically increased by changing the copper/capping layer interface. Both an additional CoWP coating and a local copper alloying with aluminum increase the bonding strength of the top interface of the copper interconnect line, and consequently, electromigration-induced mass transport and degradation processes are reduced significantly.
Statistical Analysis of Electromigration Lifetimes and Void Evolution for Cu Interconnects
Authors: Hauschildt M. , Gall M. , Thrasher S. , Justison P. , Michaelson L. , Hernandez R. , Kawasaki H. , Ho P. S. 
Published: April 2011

AbstractElectromigration (EM) failure statistics and the origin of the lognormal deviation (σ) for Cu interconnects have been investigated by analyzing the lifetime statistics and void size distributions at various stages during EM testing. Experiments were performed on 0.18 μm wide Cu interconnects with tests terminated after specific amounts of resistance increases, or after a specified test time. Void size distributions of resistance-based, as well as time-based EM tests were obtained using focused ion beam (FIB) microscopy. The lifetime and void size distributions were found to follow lognormal distribution functions. The σ values of EM lifetime and time-based void size distributions decrease with higher percentages of resistance increase, reaching an asymptotic value of σ ∼ 0.14. In contrast, σ values of resistance-based void size distributions are significantly smaller and do not show an obvious dependence on time. The statistics of resistance-based void size distributions can mainly be accounted for by geometrical variations of the void shape, while the statistics of time-based void size distributions requires consideration of kinetic aspects of the EM process. The σ values of EM lifetime distributions at long times can be simulated based on measured void size distributions, taking into account geometrical and experimental factors of EM. In contrast, for short times the statistics of initial void formation and the kinetics of interfacial mass transport have to be considered.