bluuebunny/crossref_metadata_2025_split huggingface dataset:
Combined Main- and Side-Chain Azobenzene Polyesters: A Potential For Photoinduced Nonlinear Waveguides
Authors: Sahlén F. , Geisler T. , Hvilsted S. , Holme N. C. R. , Ramanujam P. S. , Petersen J. C. 
Published: April 2011

ABSTRACTNew combined main- and side-chain azobenzene polyesters, which exhibit an intensity dependent refractive index, have been prepared in order to optically fabricate nonlinear waveguides. Novel sulfone azobenzenes, a diester, (4-[[5-(ethoxycarbonyl)pentyl]sulfonyl]-4'-[[5-(ethoxycarbonyl)pentyl]methylamino] azobenzene, and a diol, 4-[[(8-hydroxy-7-methylhydroxy)-octyl]sulfonyl]-4'-N, N-dimethylamino azobenzene, have been used to prepare new polyesters by transesterification in the molten state. The polyesters have been characterized by UV-visible spectroscopy, differential scanning calorimetry (DSC), size exclusion chromatography (SEC), third harmonic generation (THG) and optical anisotropy measurements. The molar masses of the polyesters were in the range of 5000-10000 g mol−1, which was sufficient in order to spin coat thin films. From THG measurements the polymers are shown to possess an offresonance electronic X(3) of the order 10−12 esu corresponding to a nonlinear refractive index of 2.3×10−14 cm2/W.
Design and Synthesis of Dendrimers with Enhanced Two-Photon Absorption
Authors: Elandaloussi E. H. , Spangler C. W. , Dirk C. , Casstevens M. , Kumar D. , Burzynski R. 
Published: April 2011

ABSTRACTModel dendrimers based on bis-(diphenylamino)stilbene repeat units have been synthesized and shown to have very stable bipolaronic charge states. Calculations at the AM-1 level predict two orders magnitude enhancement in the third-order nonlinearity in going from the neutral to bipolaron state. Measurement of two-photon cross-sections for PPV dimers with attached diphenylamino donor groups show enhanced two-photon cross-sections for ns pulses. Preliminary evaluation of one of the model dendrimers indicates even larger two-photon cross-sections are possible.
Langmuir-Blodgett Films of Squarylium Dye J-Aggregates Exhibiting Femtosecond Optical Responses
Authors: Furuki M. , Kawashima H. , Tani T. , Pu L. S. 
Published: April 2011

ABSTRACTJ-aggregates of squarylium dyes in Langmuir films have been found to exhibit highly efficient and ultrafast nonlinear optical properties. We established a novel method for making Langmuir- Blodgett (LB) films of J-aggregates with a single absorption band at 784 nm. Deposition of the LB-films was carried out under excess compression of the Langmuir films at a constant speed. Coating the surface of the LB-film with a glassy poly-perfluorocarbon was found to enhance and stabilize the formation of J-aggregates. Characterization of morphology using a near-field scanning optical microscope (NSOM) showed that this LB-film has a highly ordered structure comprising 2- dimensional domains of J-aggregates. We also observed nonlinear-optical responses from this LBfilm. Ultrafast decay of absorption change (250 fs) with quite low saturation energy (3.4 μJ/cm2•pulse) was observed in femtosecond pump-probe measurements. These results suggest highly delocalization of excited states in the J-aggregates of this LB-film with the 2-dimensional mono-molecular layer structure which initially formed in the Langmuir film.
In-Situ Electromigration Damage of Al Interconnect Lines and the Influence of Grain Orientation
Authors: Buerke A. , Wendrock H. , KÖtter T. , Menzel S. , Wetzig K. , Glasow A. v. 
Published: April 2011

AbstractIn this work the authors want to report some experiments concerning unpassivated Al interconnect lines of 8 and 1.4 microns width which have been damaged by in-situ electromigration in the SEM (temperature 230°C, current density 2 and 4×106 A/cm2, respectively). The wider line represents a polygrained structure with few blocking grains spanning the whole width, whereas the narrow line shows bamboo structure. Before electromigration, the local orientation and thus the position of all grain boundaries was mapped by EBSD technique along the entire interconnect line. During and after in-situ current loading in the SEM, the damaged sites were correlated with the grain boundary map to locate where the diffusion paths are situated most likely. It was found that not the deviation from <111> fibre texture, but the misorientation class of the grain boundaries is essential for the localization of the fatal defects.
Measurement of Thin Film Mechanical Properties by Microbeam Bending
Authors: Florando J. , Fujimoto H. , Ma Q. , Kraft O. , Schwaiger R. , Nix W. D. 
Published: April 2011

AbstractAn improved microbeam bending technique has been developed for the study of mechanical properties of thin films on substrates. This testing method utilizes a triangular beam geometry and improved micromachining techniques compared to previously used methods. The technique permits the stress-strain law for a metal film on a substrate to be determined. Single crystal Si beams and bi-layer Si/Al beams of lengths 25–100 pgm have been fabricated and tested. The beams are deflected with a nanoindenter, which accurately imposes a load on the beam and measures the corresponding displacement. For the bi-layer beams, a simple numerical model utilizing a Ramburg-Osgood constitutive law the film has been developed to determine the stress-strain behavior of the Al film.
Subcritical Debonding of Multilayer Interconnect Structures: Temperature and Humidity Effects
Authors: Lane Michael , Dauskardt Reiner , Ma Qing , Fujimoto Harry , Krishna Nety 
Published: April 2011

AbstractThin film structures may fail by progressive or time-dependent debonding at stresses far below those required for catastrophic failure. Previous work has shown that progressive debonding in a typical interconnect structure occurs either along the TiN/SiO2 interface or parallel to this interface in the SiO2 Such subcritical debonding was found to span several orders of magnitude of debond growth rates and occur at significantly reduced driving forces. The presence of SiO2 at the failure location indicates that the mechanisms which give rise to stress corrosion cracking in bulk glasses may also play a role in the subcritical debonding behavior of multilayer interconnect structures. Accordingly, this work focuses on the effects of temperature and humidity on subcritical debonding and rationalizes them in terms of the relevant chemical reactions taking place at the debond tip.
Thermal Studies on Stress-Induced Void-Like Defects in Epitaxial-CoSi2 Formation
Authors: Ho C. S. , Pey K. L. , Tung C. H. , Tee K. C. , Prasad K. , Saigal D. , Tan Jackie J. L. , Wong H. , Lee K. H. , Osipowicz T. , Chua S. J. , Karunasiri R. P. G. 
Published: April 2011

AbstractWe report experimental findings on the thermal-induced stress-voiding observed during epitaxial CoSi2 formation on patterned Si(100) wafers associated with the Co/Ti-interposing layer scheme [1–6]. The first rapid thermal process (RTP) in a typical SALICIDE process was studied by varying the temperature and the RTP ramp-up rate. Based on ex-situ cross-sectional transmission electron microscopy (XTEM), crystal defects were observed at shallow trench isolation (STI)/Si and gate spacer/Si edges after annealing at temperatures greater than 520°C. In addition, isothermal anneals for various time periods resulted in increased encroachment of an ultra-thin CoSi2-phase at the STI/Si edge. Higher temperature anneals also resulted in a corresponding increase in void size. In addition, higher ramp-up rates led to a thicker CoSi2 “pocket” film at the tensile-stressed STI/Si edge, aligned epitaxially along the {111}-habit planes. Our attempts to bypass the CoSi formation in order to alleviate the anomalous Si diffusion was found to be irrelevant to the voiding issue, due to the inherent nature of this film stack system to nucleate CoSi2 as the first phase. By comparing our experimental observations of voiding with Hu's analysis of the trench isolation stress fields, we found good agreement with the predicted stress field distribution in the active Si and STI/Si edge with the locations of void nucleation. The anomalously large stress induced is still not known, but can be attributed to the encroaching CoSi2 film which tends to realign epitaxially along the STI/Si interface.
Oxide Mediated Epitaxial Growth of CoSi2 in a Single Deposition Step
Authors: Ohmi S. , Tung R. T. 
Published: April 2011

AbstractA number of modifications of the oxide-mediated epitaxy (OME) technique are presented which have enabled the growth of thick (∼25–40nm) epitaxial CoSi2 layers in a single deposition sequence. The uses of (a) a thin Ti cap, (b) a thin Ti blocking layer, (c) the codeposition of Co-rich CoSix, and (d) the co-deposition of Col−xTix. have all been shown to lead to improved epitaxial quality over the pure Co OME process, for Co thickness greater than 6nm. Essentially uniform, single crystal silicide layers of over 25nm have been grown in a single deposition step. These results are supportive of the proposed role of a diffusion barrier/kinetics retarder on the part of the interlayer in the OME and the Ti-interlayer mediated epitaxy processes.
The Influence of Ti Capping Layers on CoSi2 Formation in the Presence of Interfacial Oxide
Authors: Detavernier C. , Donaton R. A. , Maex K. , Jin S. , Bender H. , Van Meirhaeghe R. , Cardon F. 
Published: April 2011

AbstractIn this work, we will show that a reactive Ti capping layer can reduce oxide layers that are present at the cobalt-silicon interface. We have used a thin, chemically grown oxide to have a well-controlled form of interfacial oxide layer. To study the silicidation reaction, isochronal annealing was done at various temperatures. Different sets of samples were made in order to investigate the influence of the thickness of the Co layer and its Ti cap. Titanium capping strongly influenced the silicidation reaction. We have found that already at moderate temperatures, Ti can diffuse towards the Co/Si interface, and can reduce the interfacial oxide there present, enabling CoSi2 formation. The CoSi2 thus formed has a preferential epitaxial orientation, and the process by which this epitaxy is attained may be explained by a combination of OME (Oxide Mediated Epitaxy) and TIME (Titanium Mediated Epitaxy).
Influence of the as and BF2 Junction Implantation on Stress Induced Defects During Ti- and Co/Ti-Silicidation
Authors: Steegen A. , Bender H. , Wolf I. De , Maex K. 
Published: April 2011

AbstractWhen scaling down the MOS technology, the increasing local mechanical stress induced during the Ti- and Co/Ti silicidation can exceed the critical shear stress on the {111}<110> active glide system in the silicon substrate. This results in the heterogeneous nucleation of 60° dislocations in the silicon substrate underneath the silicide line. In the case of an undoped silicon substrate, these dislocations nucleate at the edge of the silicide lines and are parallel with the [110] oriented line edge. This paper will investigate the effects of As and BF2 junction implantation and implantation defects on the stress developed during the silicidation reaction and on the nucleation and growth of the stress induced 60° dislocations in the silicon.
Transamination in Pulsed DC-Plasma Enhanced CVD Of Ti(C,N) From TDMAT
Authors: Driessen J. P. A. M. , Kuypers A. D. , Schoonman J. 
Published: April 2011

AbstractFavourable gas-phase conditions for deposition of Ti(C,N) from tetrakis(dimethylamine)titanium (TDMAT) in a pulsed DC-plasma have been determined, making use of mass spectroscopy. Decomposition of TDMAT in a pure hydrogen plasma results in the favourable cleavage of dimethylamine from TDMAT but prevents the formation of Ti(C,N) due to the lack of nitrogen and carbon. Addition of N2 to the hydrogen plasma results in the formation of NHx (l<x<4), opening possible transamination pathways. Transamination plays an important role in thermal CVD processes and results in high quality TiN layers. However, an undesired side-effect is the gas-phase particle formation under the conditions used here, possibly due to TDMAT - N2 interactions. The depletion of TDMAT by interaction with nitrogen in a H2(85%) - N2(15%) plasma proceeds in a mechnistic step with a rate constant of k = 4.7 × 10−14 cm3 mol−1sec. Results were compared with those obtained from using ammonia under similar process conditions, and with results from thermal CVD. Seemingly high quality Ti(C,N) coatings were deposited at temperatures between 200°C and 425°C on steel and glass with this simple and, therefore, interesting set-up.
Formation Mechanism of Metal-Oxides on Plasma-Exposed Wsi/Poly Si Gate Stacks
Authors: Liu Ziyuan , Kawashima Y. , Komatsu A. , Hamada T. , Kawano H. , Shiotani K. 
Published: April 2011

AbstractThe formation mechanism of deformed tungsten oxides (WOx, x=2,3) on WSix/poly Si gate stacks has been investigated. It was revealed that plasma etching process introduced oxygen impurity into WSix surface and caused the WOx formation during the subsequent thermal oxidation. WSix films preferred corientation were found to be stable in the oxidation process after plasma etching process.
Copper-Based Ohmic Contacts For The SiGe/Si Heterojunction Bipolar Transistor (HBT) Structure
Authors: Das K. , Alterovitz S. A. 
Published: April 2011

AbstractA Cu-based metallization scheme has been studied for establishing low resistance contacts for a Si/SiGe/Si heterojunction bipolar transistor (HBT) structure. As-grown doped layers were further implanted with BF2 and As ions for the p-type base and n-type emitter layers, respectively, in order to produce a low sheet resistance surface layer. Contacts were metallized using an e-beam deposited multilayer structure of Ti/Cu/Ti/Al. Specific contact resistances of the order of 10−7 Ω cm2 or lower were obtained.
In Situ XPS Study of Interaction of Thin IVA, VA Metal Films with Native Oxide on Si Substrates
Authors: Sushkova N. M. , Akimov A. G. 
Published: April 2011

AbstractPhase formation and change in morphology of Ti, V and Nb oxide films on (100)Si and (111)Si, with native oxide layer, have been studied by XPS in situ. The metal oxides were formed by the interaction at room temperature in UHV multistep deposited of Ti, V or Nb with native oxide. The formation of clean silicon regions during the growth of three-dimensional metal oxide islands is discussed. Differences observed in composition of Nb oxides on (100) Si and (111) Si are considered.
Nucleation and Growth of CVD Cu Films
Authors: Kröger R. , Eizenberg M. , Cong D. , Yoshida N. , Chen L. Y. , Chen L. 
Published: April 2011

AbstractIn this work the nucleation and growth of CVD Cu on MOCVD TiN barrier layer as well as on PVD Ta with and without a PVD Cu seed layer on top were studied. Scanning and transmission electron microscopy was used to characterize the dependence of morphology and microstructure on deposition time. XRD measurements were carried out to study the orientation of the polycrystalline films. Atomic force microscopy was applied to investigate the surface topography. A random crystal orientation and an amorphous interlayer between the CVD Cu film and the barrier - leading to a poor adhesion performance of the CVD Cu films - were obtained on Ta and TiN, where island growth can be observed. A CVD Cu film deposited on top of PVD Cu leads to a highly preferred <111> orientation and a significantly improved adhesion of the Cu film. A PVD Cu seed layer as thin as 60 Å was found to produce an epitaxially grown <111> textured Cu film. These results highlight the importance of the initial growth stages for both morphology and adhesion of the CVD Cu films.
CVD Cu Process Development and Integration for sub-0.18 µm Devices
Authors: Zhang Jiming , Denning Dean , Braeckelmann Greg , Hamilton Greg , Lee J. J , Venkatraman Ram , Fiordalice Bob , Weitzman Elizabeth 
Published: April 2011

AbstractThe advent of inlaid Cu interconnects has presented new challenges for the industry to fill high aspect ratio dual inlaid features. CVD Cu offers advantages for excellent step coverage and is a technique extendible for future generations of devices. We have developed a robust CVD Cu process and a CVD/PVD reflow integration scheme. In this paper, we present results of an extensive study on CVD Cu process development and integration. The effects of various precursors, carrier gases (H2, He and N2) and barrier layers including CVD TiN, PVD Ta, PVD TaN, PVD Ta-Si-N, and a hybrid barrier, on the CVD Cu film properties and device electrical properties are discussed. The extendibility and challenges of current CVD Cu processing will also be discussed.
Comparison of Copper CVD Using Cu(FOD)2 and Cu(HFAC)2 Reduction
Authors: Boey J. S. , Griffin G. L. , Maverick A. W. , Fan H. 
Published: April 2011

AbstractWe have measured the growth rate and film properties for the chemical vapor deposition of copper thin films using H2 reduction of Cu(fod)2 [H(fod) = 6,6,7,7,8,8,8-heptafluoro-2,2- dimethyl-3,5-octanedione]. The results are directly compared to deposition using Cu(hfac)2 [H(hfac) = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione]. Higher growth rates are obtained using Cu(fod)2, in part because of differences in reaction order between the two compounds. However, both compounds exhibit significant cluster formation during film nucleation, which leads to residual porosity and film resistivities above 2 µΩ-cm.
Numerical Simulations of Topographic Evolution for Sputter Deposition into Trenches and Vias
Authors: O'Sullivan Peter L. , Baumann Frieder H. , Gilmer George H. 
Published: April 2011

AbstractWe have performed 2D and quasi-3D numerical simulations of physical vapor deposition (PVD) into high aspect ratio trenches and vias used for modem VLSI interconnects. The topographic evolution is modeled using (continuum) level set methods. The level set approach is a powerful computational technique for accurately tracking moving interfaces or boundaries, where the advancing front is embedded as the zero level set (isosurface) of a higher dimensional mathematical function. First, we study the 2D case of long rectangular trenches including 3D out-of-plane target flux. The 3D flux is obtained from molecular dynamics computations for AI(100), and hence our approach represents a hybrid atomistic/continuum model. We obtain good agreement with X-TEM data. Secondly, we report results of axisymmetric 3D simulations of high aspect ratio vias which we then go on to compare with experimental data for Ti/TiN barrier layers. We find that the simulation data (using the cosine angular distribution) overpredict bottom coverage in some cases by approximately 20%-30% for both collimated and uncollimated deposition but in other cases provide a reasonably accurate comparison with experiment.
Reliability Studies of Cu using Wafer Level Joule Heated Electromigration Test
Authors: Low Kia Seng , O'Neill Anthony 
Published: April 2011

AbstractIn this paper, we describe some of the results that we have obtained using Wafer Level Joule Heated Electromigration Test and Current Ramp Test. The results indicate that the Cu we tested is more resistive to open failure due to current ramp than Al-1%Si-0.5%Cu. The value of the activation energy for electromigration of Cu using fixed current under wafer level joule heated electromigration test is 0.59 eV. The activation energy due to the effect of temperature gradient failure mechanism is 0.82 eV.
Study of Electrochemical Deposition of Copper and Microstructure Evolution in Fine Lines
Authors: Grunow Stephan , Diatezual Deda , Seo Soon-Cheon , Stoner Timothy , Kaloyeros Alain E. 
Published: April 2011

AbstractAs computer chip technologies evolve from aluminum-based metallization schemes to their copper-based counterparts, Electrochemical Deposition (ECD) is emerging as a viable deposition technique for copper (Cu) interconnects. This paper presents the results of a first-pass study to examine the underlying mechanisms that control ECD Cu nucleation, growth kinetics, and post-deposition microstructure evolution (self-annealing), leading to the development and optimization of an ECD Cu process recipe for sub-quarter-micron device generations. The influence of bath composition, current waveform, type and texture of Cu seed layer, and device feature size (scaling effect) on the evolution of film texture, morphology, electrical properties, and fill characteristics was investigated using a manufacturing-worthy ReynoldsTech 8” wafer plating tool. Resulting films were analyzed by X-ray Diffraction (XRD), four-point resistivity probe, Focused-Ion-Beam Scanning Electron Microscopy (FIB-SEM), and Atomic Force Microscopy (AFM). These investigations identified an optimized process window for the complete fill of aggressive device structures with pure Cu with resistivity ∼ 2.0 µΩ-cm and smooth surface morphology.
The Intercorrelation Between Microstructure and Chemicalmechanical Polish of Metal Thin Films
Authors: Tseng Wei-Tsu , Wang Ying-Lang 
Published: April 2011

AbstractThe correlation between microstructures of Al and W metal thin films and their respective CMP performance is investigated. It is found that CMP removal rate decreases with increasing grain size. In both cases, the textures of the metal films are altered and their resistivity increased after CMP. The phenomenon is more pronounced for polish under a greater down force. The table speed, on the other hand, has only minimum effects on microstructure and resistivity. The possible underlying mechanisms leading to this phenomenon are proposed and their potential impacts on metallization reliability is discussed.
Effects on Selective CVD of Titanium Disilicide by Substrate Doping and Selective Silicon Deposition
Authors: Maa Jer-shen , Howard David J. 
Published: April 2011

AbstractDuring selective chemical vapor deposition (CVD) of titanium disilicide on silicon, consumption of As implanted silicon substrates is enhanced relative to Si substrates implanted with other species. In this study, a selective epitaxially grown Si (SEG Si) layer has been deposited prior to selective CVD of titanium disilicide on samples with different implanted doses of either As or B. If no SEG Si film is deposited, the selective CVD TiSi2 film properties strongly depended on dopant type (As vs. B) and on dopant dose. Addition of a SEG Si film prior to selective CVD TiSi2 improves process stability as a function of changes in initial ion implanted conditions. Use of a SEG Si film prior to selective CVD TiSi2 results in values of TiSi2 thickness and TiSi2 sheet resistance which are approximately constant as a function of initial ion implant dose, and are approximately equal for both the As and B implanted samples used in this study.
Line-Width Dependence of Void Formation in Ti-Salicided BF2-Doped Polysilicon Lines
Authors: Chua H. N. , Pey K. L. , Siah S. Y. , Lim E. H. , Ho C. S. 
Published: April 2011

AbstractWe report the first observation of voids in sub-quarter micron Ti-salicided BF2-dopedpolycrystalline silicon (polySi) lines. Some of the voids, with sizes ranging from 10 to 100nm, can be clearly seen on the surface of the TiSi2 film whereas others are situated below the TiSi2 surface. The void density and size increase with decreasing polySi line-width, especially for line-widths < 0.24 µm. The voiding phenomenon was also observed to be moresevere for TiSi2 fabricated with enhanced salicidation techniques such as pre-amorphization-implant(PAl) and implant-through-metal (ITM) as compared to the conventional salicidationmethod without amorphization. The origin of the voids is found to coincide with the fluorinepeak at the TiSi2/polySi interface in the SIMS depth-concentration profiles.