bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metal Impurity Mapping in Semiconductor Materials Using X-Ray Fluorescence
Authors: McHugo S.A. , Thompson A.C. , Padmore H. 
Published: April 2011

AbstractWe present x-ray fluorescence (XRF) results from studies of metal impurities in silicon. A synchrotron-based XRF microprobe, with μm spatial resolution, was used to detect and map the impurities. The sensitivity of the XRF microprobe was determined for copper and iron in silicon using well-characterized standard samples. We have concluded the system can detect one iron or copper precipitate in silicon with a radius of ≈14nm. This sensitivity pertains to other relevant impurities in silicon, such as, chromium, manganese, cobalt, nickel and gold. Furthermore, we have detected and spatially mapped metal impurity precipitates in silicon, which are undetectable by Energy Dispersive Spectroscopy in a Scanning Electron Microscope. These results exhibit the extraordinary sensitivity of the XRF microprobe for metal impurities in semiconductors.
Phosphorus Passivation of GaAs
Authors: Watkins S.P. , Xu X. , Hu J. , Ares R. , Yeo P. , Harrison D.A. , Thewalt M.L.W. , Bolognesi C.R. , Springthorpe A.J. 
Published: April 2011

AbstractWe have performed a systematic study of the effect of various phosphorus passivation techniques on the room temperature photoluminescence (PL) intensity of undoped GaAs. The effects of passivation by two methods are compared: (1) the P-exchange reaction on exposure to tertiarybutylphosphine (TBP) vapour between 500-620°C, and (2) the growth of thin layers of GaP directly on GaAs. An x-ray diffraction technique was used to estimate the thickness of the passivating layers. Reflectance difference spectroscopy indicated a similar chemical origin for the two passivation methods. Both passivation techniques resulted in strong enhancements in the room temperature PL. PL intensity was observed to increase very rapidly with adsorbed P for both cases saturating at approximately 2 monolayers equivalent GaP coverage.
A Study of Solder Paste Rheology for The Alternative Assembly and Reflow Technology (AART) Process
Authors: Murthy S.T. , Manessis D. , Srihari K. , Westby G.R. 
Published: April 2011

ABSTRACTSolder paste performance related properties such as stencil print quality, viscosity, thixotropy, and slump resistance are of great importance in the pre-reflow stages of the electronics assembly process. This paper focuses on the study of the rheological behavior of solder paste and its correlation to process performance during the various steps of the Alternative Assembly and Reflow Technology (AART) process. This technology aims to integrate the Printed Circuit board (PCB) assembly process for both through hole and surface mount components. Four solder pastes were considered in this study and their rheological characteristics were identified through flow and oscillation tests. The oscillation tests provided the linear viscoelastic characteristics of solder paste whereas the flow tests revealed information on the yield stress as well as the degree of shear-thinning and thixotropy of the solder paste. Pastes with high elastic properties and yield stress exhibited good hot slump resistance. Furthermore, extensive shear thinning of the paste facilitated the filling of the Plated-Through-Hole (PTH) sites. Recommendations are provided for tailoring the properties of a solder paste to meet the needs of the AART process.
Reliability and Lifing Methodologies for Microelectronic Systems
Authors: Reifsnider Ken 
Published: April 2011

ABSTRACTIntegration of core electronic functions is progressing at a remarkable rate. The high-end computers that we are using now may be available on a single die by the turn of the century. The effect of this, and other advances on semiconductor assembly and packaging has generated the need for integrated component-level electrical thermal, and mechanical models and simulation methods, as described in the Semiconductor Industry Association national Technology Roadmap for Semiconductors. Although corporate and university research and development in the semiconductor area is intense (there are eight major university-based packaging centers around the world, for example), design/development methodologies that consider the combined and interactive effects of mechanical, thermal and chemical conditions on the reliability and durability of integrated components have been slow to develop. However, such methodologies have been developed for applications of complex composite systems in various other technologies where the operating conditions are similar. The present paper will discuss those developments and the possibility of applying that technology to microelectronic systems.
Molecular Modeling as a Tool for Adhesive Performance Understanding
Authors: Iwamoto N. , Pedigo J. , Grieve A. , Li M. 
Published: April 2011

ABSTRACTAs higher levels of reliability are sought, it will become increasingly important to understand the relationship between the adhesive formulation and its bonded substrate. Johnson Matthey has been addressing this need by using molecular modeling to simulate the physical effects of adhesive components on properties such as adhesion, surface spread or bleed, and underfill flow. By using a molecular modeling method as opposed to a continuum calculation, the individual components of an adhesive may be theoretically manipulated without pre-determination of properties or property effects. The potential utility of the technique lies in the prediction or confirmation of property trends when different components or processes are used. Additionally, the molecular scale helps to gain insight of the interfacial contribution to performance.
A Combined Analysis of Moisture Diffusion with Interface Fracture Mechanics on the Interface Delamination in the Plastic IC Packages During Reflow Soldering
Authors: Park Y. B. , Yu Jin 
Published: April 2011

ABSTRACTThe popcorn cracking phenomenon of plastic IC packages during the reflow soldering was investigated by conducting the stress analysis of heat transfer and moisture diffusion. Vapor pressures at delaminated interfaces between the die pad and EMC(Epoxy molding compound) were calculated and mechanistic parameters such as energy release rate, stress intensity factor and phase angle were derived under various loading conditions; thermal, crack face vapor pressure and mixed loadings. It was shown that thermal loading was the main driving force for crack propagation for small cracks lengths, but vapor pressure loading played more significant role as the crack extended.
Maskless, Direct Deposition of Copper onto Aluminum Bond Pads for Flip Chip Applications
Authors: Fang M. , O'Keefe T. , Stroder M. , Shih W. , O'Keefe M. , Strawser R. , Via D. 
Published: April 2011

ABSTRACTFlip chip interconnection of integrated circuits (IC) for packaging applications such as direct chip attachment use Pb-Sn solders as the connection between the die and the substrate. Underbump metallization is typically used to transition from the non-solderable Al bond pad on the IC to a solderable surface such as copper using traditional blanket metal deposition, photolithography and etching procedures. In this study, we report for the first time the use of a novel process for selectively depositing adherent copper directly onto aluminum thin films, eliminating the need for adhesion promoting transition layers and additional patterning steps. Utilizing copper bearing organic solutions and standard electroless and electrolytic copper plating baths, as-deposited and annealed sputter deposited Al-x%Cu (x = 0 to 2) thin films were coated with metallic copper. An increase in the organically deposited copper nucleation site density was observed with increasing copper concentration in the sputtered aluminum/copper thin films. Preliminary results using focused ion beam microscopy indicated that dissolution of the aluminum oxide surface and subsequent deposition of copper by cementation occurs in the non-conducting organic solution at sub-micron reaction lengths. Qualitative adhesion testing of samples resulted in the majority of films passing the tape test. Demonstration of the process using 50 micron diameter vias in BCB coated flip chip test vehicles from MCNC will be presented.
Effect of Grain Size and Magnetic Switching Volume on Media Noise Due to Intergranular Coupling in CoCrTaPt/Cr Thin Film Media
Authors: Malhotra Sudhir S. , Lal Brij B. , Russak Michael A. 
Published: April 2011

AbstractIn this work the effect of grain size and magnetic switching volume on media noise due to intergranular coupling for CoCrTaPt/Cr thin film media deposited at substrate temperature of 160 and 260°C are investigated. The film deposited at substrate temperature of 260°C showed weaker intergranular interaction and lower media noise compared to the film deposited at 160°C. The magnetic switching volume (V*) is an important consideration for thermal stability and media noise in high density recording media. The magnetic switching volume V* for the film deposited at 160 and 260°C was calculated to be 3.7 x 10-18 and 3.2 x 10-18 cm3 respectively. The magnetic switching volume is correlated to the average Co-alloy grain size, media noise and the interactions between the grains.
Structure of Molecularly -Thin Perfluoropolyether Films on Amorphous Carbon Surfaces
Authors: Tyndall G.W. , Waltman R.J. 
Published: April 2011

AbstractSurface energies of molecularly-thin, perfluoropolyether (PFPE)-lubricated, amorphous carbon surfaces are presented as a function of the applied PFPE structure and thickness. A framework is developed to aid in the interpretation of the surface energy data. Information regarding the structure of these PFPE films adsorbed on CHx at the monolayer thickness levels is elucidated. Evidence for ordering in these polymer films is presented and interpreted to result from a combination of both, lateral cohesive interactions within the plane of the monolayer, and adhesive interactions between the PFPE monolayer and the underlying substrate.
Crystal Ion-Slicing of Magnetic and Ferroelectric Oxide Films
Authors: Levy M. , Osgood R.M. , Kumar A. , Bakhru H. , Liu R. , Cross E. 
Published: April 2011

AbstractThe epitaxial separation of single-crystal magnetic and ferroelectric oxide films is presented. Ion implantation is used to create a buried damage layer beneath the surface. The high etch-selectivity of this sacrificial layer makes it possible to detach high quality single-crystal films from bulk samples. Magnetic and electrical properties of the films are discussed.
Amorphous Rare Earth-Transition Metal Alloys for Magneto-Optical Storage
Authors: Gambino Richard J. 
Published: April 2011

AbstractAmorphous alloys of the heavy rare earth elements with cobalt and iron have magnetic and optical properties that make them ideally suited for magneto-optical mass storage media. These materials are used in all commercial erasable (MO) optical disk systems and in optically assisted magnetic storage such as the recordable music minidisk. The important properties of these materials for this application are: 1/ ferrimagnetic exchange with a magnetic compensation point near room temperature, 2/ perpendicular easy axis anisotropy when prepared under suitable conditions as thin films, 3/low media noise as compared to polycrystalline films, 4/low processing temperatures compatible with polymer substrates and 5/thermally stable when cycled repeatedly to the Curie temperature. The magneto-optical Kerr effect that is used to read the information off the disk is large at the 800 nm wavelength used in current devices but low at 400 nm. Since the areal storage density is set by the diffraction limit, improvements in shorter wavelength device performance are needed.
Magnetic and Magneto-Optical Properties of Al Substituted Bi-RIG Particles Dispersed in a Plastic Binder
Authors: Hirano T. , Yoshida K. , Yamazaki Y. , Namikawa T. , Kishi M. 
Published: April 2011

AbstractNano-size R2BiAlxFe5-xO12(R: Dy, Gd, Th) particles were prepared with a coprecipitation and annealing method. The coating films of the particles were prepared with a coating technique. The magnetic and magneto-optical properties of the particles and films were investigated. The coercive forceHcof the particles and films was increased and saturation magnetizationMs. dropped with the Al contentx. TheHcof the coating films was about 200 Oe at the compositions of dispersed particles for which theMswas almost zero. These results suggest that the increase was made with magnetic compensation. The BiTb2A10.6Fe4.4O12coating film shows Faraday rotation spectra. The figure of merit of the film is about 0.5 at 520 nm. The coating BiTb2A10.6Fe4.4O12film is one of the candidate materials for a new economical magneto-optical storage medium.
Production of Nano-Crystalline Zirconia-Based Powders Using a Flow-Through Hydrothermal Process
Authors: Darab John G. 
Published: April 2011

ABSTRACTNano-crystalline, zirconium oxide and oxyhydroxide particulates were produced using a novel, continuous, flow-through hydrothermal technology which was previously developed at the Pacific Northwest National Laboratory. Homogeneous aqueous solutions containing 0. LM ZrO(NO3)2, 0.2-0.5M urea, and in some cases 0.025-0.10M NaF were pumped at pressures of 6000-8000 psi through a heated stainless steel reaction tube at 340-350°C. Flow at pressure was maintained using a nozzle at the down-stream end of the reaction tube. In this process, termed Rapid Thermal Decomposition of precursors in Solution (RTDS), the formation of zirconium oxide and oxyhydroxide nano-crystals (diameters of generally less than 15-nm) occurred during the solution's brief residence time (<15 seconds) in the reaction tube, yielding aqueous slurries of agglomerated particulates upon exiting the nozzle. Powders were separated from these slurries, washed, then dried. RTDS powder prepared from 0.1M ZrO(NO3)2and 0.5M urea had a surface area of 210 m2/g and was determined to be a mixture of predominantly nano-crystalline (<10 nm crystallite diameter) cubic ZrO2 with the balance being monoclinic ZrO2. This powder was subsequently calcined to 500°C, pressed into a pellet at 20,000 psi and sintered at 500°C for one hour to yield a mechanically stable porous support with a measured surface area of 125 m2/g. In contrast, RTDS powder prepared from 0.1M ZrO(NO3)2, 0.5M urea, and 0.1M NaF was determined to be pure monoclinic ZrO2with a surface area of 58 m2/g.
Aluminum Foam, “Alporas”: The Production Process, Properties and Applications
Authors: Miyoshi T. , Itoh M. , Akiyama S. , Kitahara A. 
Published: April 2011

ABSTRACTThe production of foamed aluminum has long been considered difficult to realize because of such problems as the low foamability of molten metal, the varying size of cellular structures, solidification shrinkage and so on. Recently these problems have been solved by a number of researches and some manufacturers produce foamed aluminum by their own methods. We have been employing a batch casting process and manufacturing foamed aluminum under the tradename ALPORAS® since 1986. This paper presents the manufacturing process, physical properties and some typical applications of ALPORAS.
Eddy Current Characterization of Metal Foams
Authors: Dharmasena K. P. , Wadley H. N. G. 
Published: April 2011

ABSTRACTCellular materials are characterized by their relative density, pore shape and orientation, the average cell size, and the degree of pore interconnectivity which all depend upon the method and conditions used for processing. This has created an interest in non-invasive sensor techniques to characterize the foam structure. Multifrequency electrical impedance measurements were performed using an eddy current technique on open cell aluminum foam with systematically varied relative densities and pore sizes. The impedance was dominated at all frequencies by the amount of metal contained within a probed volume of foam and the tortuosity of the current path. At low frequency, the impedance data were found to be relatively insensitive to pore size variations enabling an independent measure of the relative density. At high frequency, the data indicated a strong dependence on the cell size.
In-Situ Sensing of the Expansion of Low Density Core (LDC) Ti-6Al-4V Sandwich Structures
Authors: Queheillalt D. T. , Choi B. W. , Wadley H. N. G. , Schwartz D. S. 
Published: April 2011

ABSTRACTA combination multifrequency eddy current and laser ultrasonic sensors have been used to measure the pore expansion kinetics and elastic moduli evolution during the annealing of low density core (LDC) Ti-6Al-4V sandwich structures. The LDC samples were heated to 920°C and held there for up to 12 hr. The eddy current sensor measured the sample thickness (i.e. relative density) and revealed that the samples began to expand early during heating and was nearly complete after 4 hr at 920°C. The laser ultrasonic sensor measurements indicated a concomitant decrease in the elastic moduli with the reduction in relative density. The combination of an eddy current and laser ultrasonic sensor is therefore able to measure both the density and the elastic moduli independently during the annealing stage of LDC Ti-6Al-4V sandwich structure processing providing a simple method for directly controlling the parameters most critical to aerospace applications of these new materials.
Polycrystalline Sil-x-yGex.Cy for Suppression of Boron Penetration in PMOS Structures
Authors: Chang C. L. , Sturm J. C. 
Published: April 2011

ABSTRACTWe have fabricated polycrystalline Sil-x-yGexCy by Rapid Thermal Chemical Vapor Deposition and used it as part of a polycrystalline gate structure for PMOS devices. The results showed that the use of carbon in polycrystalline Sil-x-yGexCy suppressed boron penetration across the gate oxide. No effects of gate depletion with the use of poly-Sil-x-yGexCy were observed. Our work suggests that the addition of carbon reduced the chemical potential of boron in Sil-x-yGexCy, which deterred boron from diffusing across the underlying gate oxide.
Characterisation of Low Energy Boron Implantation and Fast Ramp-Up Rapid Thermal Annealing
Authors: Collart E. J. H. , de Cock G. , Murrell A. J. , Foad M. A. 
Published: April 2011

ABSTRACTThe effects of ramp-up rate during rapid thermal processing of ultra-shallow boron implants have been investigated. Ramp-up rates were varied between 25 °C and 200 °C for two types of anneals: soak anneals and spike anneals. It was found that the ramp-up rate had very little influence on junction depth or electrical activation for both types of anneals. Spike anneals did produce shallower profiles than soak anneal for a comparable electrical activation and may be an option for future processes.
Process Design & Integration of Salicide and Source/Drain Process Modules for Improved Device Performance
Authors: Apte Pushkar P. , Saxena Sharad , Rao Suraj , Vasanth Karthik , Prinslow Douglas A. , Kittl Jorge A. , Breedijk Terence , Pollack Gordon 
Published: April 2011

ABSTRACTIn integrated circuit (IC) fabrication, understanding and optimizing process interactions and variability is critical for swift process integration and performance enhancement, especially at dimensions ≤0.25μm. We present here an approach to address this challenge, and we apply it to improve the process design for two critical modules in a typical CMOS IC process—salicide and source/drain. Together, these modules impact the silicide-to-diffusion contact resistance (Rc), and the gate sheet resistance (Rs); which, in turn, significantly affect transistor series resistance and circuit delays respectively. In our approach, we have investigated a process domain consisting of both silicide and source/drain process variables; and we have developed a quantitative framework for analysis and optimization, along with qualitative insight into underlying the physical mechanisms. We demonstrate that the transistor drive current (Id) improves by ≈5‥, and circuit performance, as measured by the figure-of-merit (FOM), by ≈4‥. This improvement is significant, and an added benefit is that other transistor characteristics such as effective channel length, off-current, substrate current etc. are affected minimally. Finally, we use this approach to optimize trade-offs such as Rc vs Rs and performance vs manufacturability; thus enabling manufacturable processes that meet the requirements for high performance.
Bandgap Shifting of an Ultra-Thin InGaAs/InP Quantum Well Infrared Photodetector via Rapid Thermal Annealing
Authors: Sengupta D. K. , Kim S. , Kuo H. C. , Curtis A. P. , Hsieh K. C. , Bishop S. G. , Feng M. , Stillman G. E. , Gunapala S. D. , Bandara S. V. , Chang Y. C. , Liu H. C. 
Published: April 2011

ABSTRACTWe demonstrate that SiO2 cap rapid thermal annealing in ultra-thin p-type InGaAs/InP quantum wells can be used to produce large blue shifts of the band edge. A substantial bandgap blue shift, as much as 292.5 meV at 900°C has been measured and the value of the bandgap shift can be controlled by the anneal time. Theoretical modeling of the intermixing effect on the energy levels is performed based on the effective bond-orbital method, and we obtain a very good fit to the photoluminescence data. Compared to the as-grown detector, the peak spectral response of the annealed detector was shifted to longer wavelength without any major degradation in the responsivity characteristics.
On the Entrance Effects and the Influence of Buoyancy Forces on the Fluid Flow In Rtp Reactors
Authors: Rainova Yu. P. , Antonenko K. I. , Pezoldt J. , Schenk A. 
Published: April 2011

ABSTRACTFlow and heat transfer effects play a critical role in chemical vapour deposition (CVD) reactors. Holographic interferometry offers the possibility to study the flow dynamics of an entire region in real time under process conditions with negligible disturbances of the investigated process. The advantage of the method is the possibility of accurate measurements of flow patterns and temperature profiles in a fast dynamic process under actual experimental conditions. Mixed and forced flow conditions were studied for two gases with distinct different thermophysical properties. The influence of the gas inlet system and buoyancy forces on the resulting fluid flow are highlighted. A special attention was drawn on the visualization of edge effects.
In-Line Ambient Impurity Measurement on a Rapid Thermal Process Chamber by Atmospheric Pressure Ionisation Mass Spectrometry
Authors: Kondoh Eiichi , Vereecke Guy , Heyns Marc M. , Maex Karen , Gutt Thomas , Nwnyeil Zsolt 
Published: April 2011

ABSTRACTGaseous impurities in the chamber of a SHS2800ε rapid thermal processor were quantitatively measured by using atmospheric pressure ionisation mass spectrometry (APIMS). APIMS is a very sensitive technique to detect trace impurities in a bulk (1 atm) gas. A wide dynamic range (0.1 ppb - 10 ppm) measurement was successfully performed, which allowed in-situ monitoring of impurities during RTP. This work reports the fundamental behaviour of ambient impurities originating from different sources. The sources discussed in this paper are threefold: system background, wafer loading, and the wafer itself. Ambient management requires a better understanding of the independent contribution of each source on processing.
Ripening Mechanisms in Ultrathin Metal Films
Authors: Rosenfeld Georg , Essera Marcus , Morgensternat Karina , Comsa George 
Published: April 2011

AbstractResults of recent experimental model studies on ripening of submonolayer films via Ostwald ripening and dynamic coalescence are described. The experiments have been performed on ensembles of Ag-adatom or vacancy islands on a Ag(111) surface using Scanning Tunneling Microscopy. For Ostwald ripening of adatom islands, deviations from the classical mean-field ripening behaviour are observed which show up as pronounced local correlations in island decay and growth rates. For ripening via dynamic coalescence which is studied for ensembles of vacancy islands, it is found that the increase of the average island size with time in the late-stage regime is correctly described by the classical binary collision model.