bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature and Field Dependence in Polymer Light Emitting Diodes
Authors: Bozano L. D. , Carter S.A. , Scott J.C. , Malliaras G.G. , Brock P.J. 
Published: April 2011

ABSTRACTWe investigate the electrical properties of Polymer Light Emitting Diodes (LED's). The experimental data consists of steady state current-voltage characteristics and radiance as a function of temperature.The basic LED structure is Anode/MEH-PPV (2-methoxy,5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene)/Cathode, with a polymer film 120-140 nm thick. We use different anode/cathode pairs to study transport and light emission properties. Measurements of external quantum efficiency of bipolar and monopolar devices are presented from 200 K to 300 K. The electron and hole mobilities are derived in the trap-free limit and at high voltages.
Multifunctional Fullerene Films for Photonics
Authors: Liu Y. , Claus R. O. , Wang Y.X. , Lu H. , Distler T. 
Published: April 2011

ABSTRACTWe report here the preparation of highly homogeneous multifunctional fullerene thin films for photonics using the electrostatic self-assembled monolayer technique at room temperature for the first time. The monolayers and multilayers were characterized via contact angle measurements, UV-vis spectroscopy and atomic force microscopy. These results demonstrated that close-packed, highly uniform fullerene or fullerene/metal cluster films with micron-thickness could be formed on various substrates including silicon, glass, metal and plastics.
The Synthesis of Diphenylpolenes and PPV-Oligomers Incorporating Diphenylphosphino Donor Groups
Authors: Madrigal L. G. , Spangler C.W. 
Published: April 2011

ABSTRACTPrevious studies of the second and third order nonlinear optical properties of organic molecules have shown enhancement of the nonlinear response when second row elements replace first row elements (e. g. S for O) in electron donating groups. Various substituted amino functionalities have been utilized extensively as strong donors in the design of molecules for both second and third order NLO applications. However, to date, no research groups have reported a systematic study of the effect of replacing N (nitrogen) by P (phosphorus) in various chromophore functionalities. We have now synthesized a series of bis(diphenylphosphio)diphenylpolyenes with up to five double bonds, a bis-(diphenylphosphino)-PPV dimer, and a diphenylphosphino DANS equivalent. The absorption characteristics compared to the N equivalents, and the implications for photonics applications will be discussed.
Synthesis and Optical Limiting Characterization of a Porphyrin-Buckminsterfullerene Dyad
Authors: McEwan Kenneth J. , Lewis Keith L. , Ang How-Ghee , Loh Zhi-Heng , Chng Leng-Leng , Lee Yiew-Wang 
Published: April 2011

ABSTRACTThe optical limiting performances of donor-buckminsterfullerene (C60) dyads have hitherto been unreported. The predicted large excited state absorption cross-section of such dyads in their charge-separated states would enable them to exhibit enhanced optical limiting relative to their individual components. We report herein the synthesis and optical limiting characterization of a novel porphyrin-buckminsterfullerene dyad, in which the porphyrin and C60 moieties are held within close proximity of one another by an o-phenylene bridge. The porphyrin-C60 dyad was synthesized via 1,3-dipolar azomethine ylide cycloaddition, and was obtained in 37.0% yield. Optical limiting measurements at 532 nm using 3-ns pulses show that the limiting performance of the dyad is poorer compared to its model compounds. Possible reasons for the worsened performance of the dyad will be discussed.
Electrical Reliability of Giant Magneto-Resistive Recording Sensors
Authors: Tsu I-Fei , Chang C. , Edelman H. S. 
Published: April 2011

AbstractThe electrical reliability of Ta/NiMn/NiFe/Co/Cu/Co/NiFe/Ta top spin valve sensors was studied. Electrical current densities in the range of 20–50 MA/cm2 were applied at 70°C ambient temperature. The combined Joule and ambient heating correspond to peak sensor temperatures of 170–300°C. Resistance and giant magneto-resistive (GMR) amplitude of the sensors were measured with time up to 800 hours. Device reliability was predicted from the Arrhenius plots of time to failure (TTF). Microstructure of sensors after stress was studied by scanning transmission electron microscope (STEM) and energy dispersive X-ray spectroscopy (EDX). The device failure mechanism is discussed on the scope of inter-layer diffusion and electromigration.
Effect of Modified Metal/Passivation Interfaces on Stress Voiding in Interconnects+
Authors: Kalnas C. E. , Keller R. R. , Phelps J. M. , Marieb T. N. 
Published: April 2011

AbstractStress and electromigration voids are believed to nucleate at the metal/passivation interface. In this study, modified interfaces were synthesized to experimentally elucidate the role of the interface on stress voiding for comparison with theoretical predictions. Interfaces were modified by depositing photoresist in a controlled manner on Ti/Algfi lines prior to passivation deposition. Stress voiding susceptibility was assessed in as-received lines as well as those subjected to storage anneals for 1, 5, and 25 days at 190°C to accelerate void formation. The global textures of all the lines were <111> fiber and were not significantly affected by the interface modification. Differences in stress voiding were attributed to the different interfaces. Higher ratios of voids in modified regions to voids in unmodified regions were observed both in as-received lines and those given a 1 day storage anneal due to the heterogeneous nucleation sites provided by the photoresist contamination in the modified regions. However, the void ratio appears to decrease exponentially with longer time anneals. Lowered driving force for void formation in the modified regions leads to less voiding with time, while higher driving force and a limited number of nucleation sites in the unmodified regions leads to more voiding with time. Local textures at a limited number of voided sites in modified and unmodified regions were identical to the global texture of the line. In our limited sampling, voids did not form in local regions of weaker <111> texture.
Kinetics of the Tial3 Formation From Al/Ti Thin Films
Authors: Federspiel X. , Ignat M. , Voiron F. , Fujimoto H. , Marieb T. 
Published: April 2011

AbstractThe interfacial reactions that may occur from the ageing of integrated circuits during operation will change their properties and produce failures. It is crucial to understand the phenomena that controls these reactions and their kinetics.The object of this work was to establish the role of impurities and grain size on the growth rate of TiAI3 from Al/Ti interfaces. The kinetic study consisted of different annealings followed by electrical measurements. These data were correlated with microstructural analysis and composition evolution from Transmission Electron Microscopy (TEM), Secondary Ions Mass Spectroscopy (SIMS).The kinetic data were fitted using a combination of classical models (parabolic, Avrami, Aronson) and complemented by a simulation, which accounts for the nucleation frequency and the grain boundary diffusion. The growth simulations were compared to microstructures observations using TEM.
Measurement of Toughness for Sin Films on Silicon Using Channel Cracking Technique
Authors: Ma Qing , Tran Quan , Sun Brad , El-Mansy Safaa , Sun Julie , Fujimoto Harry 
Published: April 2011

AbstractSilicon nitride thin films used for transistor spacer are usually under large tensile residual stresses. When a film is thick enough, it can crack by channel cracking mechanism. The toughness of these films, used in models for failure criteria, can be obtained by determining the critical thickness for channel cracking of blanket films with known residual stresses. However, depositing films of a range of different thickness to determine the critical thickness is tedious, and this process also introduces risks of producing particles in the deposition chamber when the film exceeds the critical thickness. An alternative technique is to deposit films of thickness below critical thickness and then to apply additional tensile stresses to the film by bending the substrate. A critical film stress can be determined for channel cracking from which the film toughness is obtained. This paper describes the experiments performed for a new SiN film and presents the results.
Fatigue of Silane Bonded Epoxy/Glass Interfaces
Authors: Ritter J. E. , Learned J. C. , Jacome G. S. , Russell T. P. , Lardner T. J. 
Published: April 2011

AbstractFatigue (slow) crack growth in silane bonded epoxy/glass interfaces was studied under static and cyclic loading at 23°C, 95% RH using the double cleavage drilled compression test. Crack growth rates under cyclic loading were significantly greater than under static loading, in contrast to crack growth results in monolithic glass. In addition, cyclic crack growth rate data after aging up to 94°C in distilled water were not significantly different from unaged samples; however, after aging at 98°C in distilled water and 70°C in a KOH aqueous solution of pH 10, crack growth became cohesive and fractal in nature. These results are discussed in terms of possible mechanisms for fatigue crack growth at silane bonded epoxy/glass interfaces.
Characteristics of Molybdenum Nitride Thin Film by N2+ Ion Implantation
Authors: Kim Dong Joon , Kim Ik-Soo , Kim Yong Tae , Park Jong-Wan 
Published: April 2011

AbstractMolybdenum nitride thin films were prepared by N2+ implantation with acceleration energy of 20 keV and the ion dose of 3×1017 ions/cm2. The structural property and thermal stability of the films were investigated by XRD, AES, AFM and RBS. The crystal structure of N2+ implanted molybdenum thin films (Mo-N2+) which had microcrystalline state was transformed to γ-Mo2N phase with a preferred (111) orientation after a post-annealing at 500 °C for 30min. However, a silicide reaction was not observed even after the annealing at 700 °C, which is due to the modification of the interface between Mo thin film and Si substrate by N2+ implantation. Also, Cu diffusion did not seem to be induced by the annealing at 700 °C for 30 min. The internal stress of the Mo-N2+ thin films during post-annealing at 600 °C for 30min was found to change from highly compressive stress to low tensile stress.
In-Situ Study of the Oxide Mediated Epitaxy of CoSi2 on Si
Authors: Kleinschmit M. W. , Yeadon M. , Gibson J. M. 
Published: April 2011

AbstractOxide Mediated Epitaxy (OME) shows promise as a method to form good quality, thin epitaxial CoSi2 films on most Si surfaces. We have performed an in-situ study of the OME of CoSi2, on the Si (001) surface. Our work was carried out with our specially modified ultra-high vacuum transmission electron microscope (UHV TEM) SHEBA (Surface High Energy Electron Beam Apparatus). With SHEBA we were able to monitor the diffraction pattern and therefore the phase formation throughout the anneal. Our results confirm the suppression of intermediate phases during CoSi2 formation in the OME process. We also see a difference in the as deposited Co film when the oxide coated silicon surface is used rather than a clean substrate. From combined imaging and diffraction studies we will shed some light on the mechanism behind the success of OME.
Modelling the Influence of the Silicon Doping Profile on a Silicide Well Ohmic Contact
Authors: Reeves G. K. , Holland A. S. , Leech P. W. 
Published: April 2011

AbstractLow values of contact resistance Rc(Ω) and specific contact resistance, ρc(Ωcm2) are essential for ohmic contacts to devices with ULSI dimensions. The incorporation of silicides into contact structures has made a substantial contribution towards this goal. However the modelling and characterisation of these more complex silicide contact structures still requires considerable development. The variation of doping density in the vertical direction will cause a strong local variation in silicon resistivity with depth as well as a pronounced variation in the silicon-silicide barrier layer as a function of depth.In this paper we use a three dimensional (3-D) finite element analysis of sub-micron silicide contacts to illustrate the influence on Rc of the silicon doping profile in the sourcedrain contact regions. In addition, the influence of the doping profile on the current density distribution at the silicon-silicide interface is presented. A comparison of results is made between a uniform doping profile and two ion-implanted profiles. In order to improve the model's accuracy, the often neglected contribution of the metal-silicide barrier (ρca) to Rc is taken into account. Experimental measurements using a Cross Kelvin Resistor (CKR) test structure, have been used to determine ρca (∼3–5 × 10−9Ω.cm2 ) of the aluminium-TiSi2 interface.
Effect of Nitrogen Content on Interfacial Adhesion of the Ta/SiO2Interface
Authors: Lane Michael , Dauskardt Reiner , Krishna Nety , Hashim Imran 
Published: April 2011

AbstractWith the advent of copper metallization in interconnect structures, new barrier layers are required to prevent copper diffusion into the adjacent dielectrics as well as the underlying silicon. These barriers must not only prevent interdiffusion but also provide adequate adhesion to both the dielectric and copper. Ta and TaN have received considerable attention as barrier layers in copper metallization schemes. While much has been reported on their diffusion properties, little or no quantitative data exists on their adhesive properties. We present data on both the interface fracture energy and the subcritical debonding of ionmetal- plasma sputtered Ta and TaN films on thermal silicon oxide. Data is also presented showing the significant effect of interfacial chemistry, particularly varying nitrogen contents at the TaN/SiO2interface.
TEM Analyses Of Cu-Ta And Cu-Tan Interfaces
Authors: Wang J. Y. Phillip , Zhang Hong , Hashim Imran , Dixit Girish , Chen Fusen 
Published: April 2011

AbstractThis paper reports an extensive interfacial study of Cu deposited on Ta and TaN barrier layers. It has been reported that the Cu/Ta interface develops a uniform and thin amorphous layer at the interface upon thermal treatment[l]. However, our high resolution transmission electron microscopy (HRTEM) analysis shows atomically sharp interfaces for all conditions without any amorphous layer at the interfaces, especially for the ones which underwent one hour annealing at 400°C and 500°C. The “amorphization” effect is only observed if the Cu/Ta TEM specimen is exposed to oxygen. It exists usually at the thinner regions of the TEM specimen or if the specimen is left in air for > 24 hours. Energy dispersion x-ray (EDX) analysis of the “amorphized” region shows that it is a mixture of Cu, Ta, and O.
The Future Of Silicide For CMOS Contacts
Authors: Roy R. A. , Cabral C. , Lavoie C. 
Published: April 2011

AbstractThis paper examines the challenges for silicide contacts in current and future CMOS technologies and assesses the capability of TiSi2 and related materials, as well as CoSi2, to meet the technology requirements. Specific issues such as maintaining low resistance in narrow lines, source/drain silicon consumption, and silicide thermal budget, are discussed. In this regard we evaluate the salient features of the basic titanium salicide process, and variations such as alloying, implantation, selective CVD, and laser silicidation. Data are presented from recent experiments to assess progress in each approach towards meeting the necessary goals. Finally, projections of the future of silicide processing are given.
Microstructural Development of Dispersion Strengthened Cu Thin Films
Authors: Weiss D. , Kraft O. , Arzt E. 
Published: April 2011

AbstractThe internal oxidation method is applied for the first time to produce a fine dispersion of second phase particles in thin films. A processing route is presented which includes ultra-high vacuum magnetron sputtering of about 1 μm thick alloy films onto Si substrates followed by insitu annealing and oxidation. Two different Cu-base alloys are examined, Cu-Y and Cu-Al, in which the extent of miscibilitiy differs significantly. This has considerable influence on the grain growth behavior. Nanoindention and wafer-curvature experiments show a drastic improvement of both room-temperature and high-temperature strength. Phenomena well known from bulk oxide-dispersion strengthened (ODS) alloys are found to appear in the thin films as well: Results on abnormal grain growth and the formation of creep voids are presented and discussed in terms of particle effects.
Bath Additive and Current Density Effects on Copper Electroplating Fill of Cu Damascene Structures
Authors: Mikkola Robert D. , Jiang Qing-Tang , Carpio Ronald , Carpenter Brad 
Published: April 2011

AbstractCopper electroplating has become the leading technology for gap fill of damascene structures on advanced interconnects. A key to developing a robust electroplating process that produces deposits free of voids and seams is understanding the role of the additive components, i.e., levelers, brighteners and wetting agents, and their relative diffusion/adsorption characteristics. Additionally, obtaining insight about the cathodic current/potential relationship is critical for maximizing the effectiveness of the additive components.Our results indicate that bath additive composition and the plating parameters (plating pulse frequency, and current density play critical roles in the outcome of the Cu fill. SEM cross sectional analysis of timed partial electroplating fill studies show two types of fill, 1) conformal and 2) bottom-up. Conformal fill of features smaller than 0.25 μm with an aspect ratio (AR) of 4.0 tends to form seam voids in the center of the structure. These seam voids can lead to early electromigration failures. On the other hand, bottom-up fill leads to a void free Cu deposit within the feature.
Room Temperature Self-Annealing of Electroplated and Sputtered Copper Films
Authors: Chen Michelle , Rengarajan Suraj , Hey Peter , Dordi Yezdi , Zhang Hong , Hashim Imran , Ding Peijun , Chin Barry 
Published: April 2011

AbstractSelf-annealing properties of electroplated and sputtered copper films at room temperature were investigated in this study, in particular, the effect of copper film thickness, electrolyte systems used, as well as their level of organic additives for electroplating. Real-time grain growth was observed by transmission electron microscopy. Sheet resistance and X-ray diffraction measurements further confirmed the recrystallization of the electroplated copper film with time. The recrystallization of electroplated films was then compared with that of sputtered copper films.
Facilitated C54-TiSi2 Formation With Elevated Deposition Temperature: A Study of CO-Deposited Layers
Authors: Ohmi S. , Tung R. T. 
Published: April 2011

AbstractThe effect of co-deposition method on the C49- to C54-TiSi2 phase transformation was investigated. Both the co-deposition ratio of TiSix layers and the deposition temperature were found to have a significant effect on the C54 phase transformation. The optimum composition to form C54 TiSi2 phase was x∼l.5 for room temperature deposition, and x∼2.0 for samples deposited at 400°C. The incorporation of a small amount of Mo had a beneficial effect on the C54 transformation in layers deposited at room temperature, but it had little effect in layers deposited at 400°C.
Characterization of Thin Dielectric Films as Copper Diffusion Barriers using Triangular Voltage Sweep
Authors: Cohen S. A. , Liu J. , Gignac L. , Ivers T. , Armbrust D. , Rodbell K. P. , Gates S. M. 
Published: April 2011

AbstractAs technology progresses, the need for thinner Cu diffusion barrier caps is becoming more important, and it is advantageous if these barriers have low dielectric constants (κ). Towards this end, we characterized Cu penetration in several thin (35 nm to 70 nm) dielectrics, including silicon nitrides, silicon oxynitrides, an amorphous hydrogenated carbon film, and a methyl silsesquioxane layer. Metal Insulator Silicon (MIS) structures were used as the test vehicle. The barrier dielectrics were deposited on 100 nm thermal oxide which was grown on 2 Ω-cm, n-type Si wafers. After the deposition of 50 nm TEOS capping layers, both Al and Cu dots were evaporated on each wafer through a mask. Both Al and Cu dot samples were stressed at +2.7 MV/cm at 300°C for 10 minutes. For Cu dots, the applied stress pushed Cu ions into the dielectric stack. Stressing Al dots characterized the effects of the stress on the dielectric stacks and the quantity of Na ions in the films. Since C-V shifts are subject to stress-related instabilities in the interfaces as well as within the dielectrics themselves, triangular voltage sweep (TVS) was used after the applied stress to measure the concentration of Cu which reached the underlying thermal oxide film. The sensitivity of the TVS test with the structures used is about 5×109/cm2. Secondary ion mass spectroscopy (SIMS) analyses were performed on some of these samples to verify the electrical results.
HRTEM Study of the Interfacial Reactions of High-Temperature Sputtered Ti Thin Films on Preamorphized (001)Si
Authors: Chang S. M , Yang H. Y , Huang H. Y , Chen L. J. 
Published: April 2011

AbstractInterfacial reactions of high-temperature sputtered Ti thin films on preamorphized (001)Si have been investigated by high-resolution transmission electron microscopy in conjunction with auto-correlation function analysis. Simultaneous presence of multiphases was found to occur in the amorphous TiSix layer at the Ti/Si interface. The enhanced transformation of C54-TiSi2 in high-temperature deposited samples is attributed to the more extensive presence of silicide crystallites, which serve as nucleation sites, in the a-TiSix layer than that in samples deposited at room temperature.
Arsenic-Only Preamorphization Process Extension For TiSi2 Formation Down to 65-nm Gate Lengths
Authors: Losavio A. , Sallagoity P. 
Published: April 2011

AbstractThe scalabilty of the titanium self-aligned silicide (Salicide) process is one of the main issues for sub-quarter micron technologies. The major difficulty is to achieve a low sheet resistance for very narrow polysilicon lines and highly doped S/D regions, without degrading the transistor performance. A preamorphization implant (PAl) performed before the titanium deposition, can achieve a low Ti silicide sheet resistance (<10 Ohms/sq) down to 0.1 Vim gate lengths [1]. Nevertheless, it has been recently reported that PAI should not be sufficient to achieve low silicide sheet resistance for narrower gate widths (< 0.1 µm) [2]. In this work, an extension of the PAI process down to 0.065µm poly-Si lines width, by only using an arsenic implant is presented, achieving a very low sheet resistance value (∼5 Ohms/sq). This result has been obtained by optimizing both the arsenic implant conditions and the silicon surface cleaning. Moreover, a large statistical analysis of the arsenic PAI process impact on 0.25µm device performances has been done, showing that a defectivity of the NMOS Ioff leakage current can appear if preamorphization implant conditions are not optimized.