bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Accelerated Stress Conditions on Electromigration Failure Kinetics and Void Morphology
Authors: Bauguess S. , Liu L. H. , Dreyer M. L. , Griswold M. , Hurley E.
Published: April 2011

Accelerated life testing has long been used to measure the electromigration reliability of integrated circuit (IC) metallization systems. In order to establish or verify electromigration design rules for IC products the measured data is extrapolated over a wide range of operating conditions using phenomenological models. These models assume that the components of the diffusional flux, thermal stress and resulting void morphology are independent of test/operating condition. In this paper, electromigration void morphology and failure criteria are studied over a range of stress conditions and microstructures for non-layered AlCu and AlCuSi metallurgies. The failure criteria, defined as the average change in conductor resistance prior to an open circuit condition, was strongly dependent on test current density. Moreover, the nature of the relationship between failure criteria and current density was governed by the linewidth (W) relative to the median grain size (D50). This dependence can be explained qualitatively in terms of the Blech Effect.
Study of Cobalt Salicide Fabrication on Sub-Quarter Micron Polysilicon Lines
Authors: Chen Wei-Ming , Pozder Scott , Limb Young , Sitaram A R , Fiordalice Bob
Published: April 2011

Comparison of anneal temperatures, sheet resistance, gate to source/drain leakage current, and implant pre-amorphization are studied for a conventional 2-step cobalt salicide process and a TiN capped cobalt salicide. The TiN capped cobalt silicide process is found to be superior to the conventional cobalt salicide process in producing lower sheet resistance and tighter sheet resistance distribution. The use of a TiN cap also suppresses Si out diffusion, which can prevent shorting between the gate and source/drain areas when pre-amorphization of Si substrate is used to enhance silicidation. The metal residue on oxide and nitride substrates after metal anneal and metal etch are compared using total reflection x-ray fluorescence. It is found that both Ti and Co residue on silicon nitride is higher than on silicon oxide after metal anneal and metal strip.
Influence of HCL on Rapid Thermal Oxides
Authors: Hames G. A. , Beck S. E. , Gilicinski A. G. , Henson W. K. , Wortman J. J.
Published: April 2011

The influence of HCl on the quality of gate oxides grown by rapid thermal oxidation has been investigated. HCl was added to oxidation ambient for some rapid thermal oxides while for others the silicon surface was annealed in a partial HCl ambient prior to rapid thermal oxidation. Improvements in gate oxide integrity were monitored on MOS capacitors and MOSFET devices by I-V and C-V testing. The levels of chlorine incorporated in the oxide from the addition of HCl to the process was measured by secondary ion mass spectroscopy. Atomic force microscopy was performed to measure surface roughening during HCl pre-oxidation treatments.
Evaluation of Applied Materials' Rapid Thermal Processor using Sematech Methodologies for 0.25 m Technology Thermal Applications-Part II
Authors: Nanda Arun K. , Riley Terrence J. , Miner Gary , Pas Michael F. , Hossain-Pas Sylvia
Published: April 2011

Under a joint development contract with Applied Materials (AMAT) and Texas Instruments (TI), SEMATECH undertook a project (Joint Development Project J100) with a goal of delivering a cost effective, technically advanced Rapid Thermal Processor (RTP). The RTP tool was specified to meet the present and future manufacturing needs of SEMATECH's member companies. The J100 results contained here will focus on the temperature and control performance of the AMAT RTP tool. The J100 results on the temperature measurement and control performance of AMAT's RTP tool using bare backside monitor wafers were presented in part I. In actual manufacturing environments the backside conditions of wafers are not consistent which causes temperature variations during rapid thermal processing. In this experiment, boron monitor wafers with varying backside conditions were used to test the uniformity, repeatability, and stability of the tool. The wafer backside films were fabricated using predictions from emissivity models and were subsequently verified by experimental techniques. In addition, perturbation experiments utilizing boron and arsenic implanted wafers demonstrated a high degree of localized temperature control across the wafers. A 3-sigma temperature variation ranging from 3.0 °C (for wafers with similar backside films) to 6.0 °C (for wafers with varying backside films) was found for all wafers processed during this evaluation. The perturbation experiments, which included a forced temperature offset of two degrees at one of the wafer temperature sensors, resulted in a noticeable change in sheet resistance across the wafer.
Study of Nitrogen Incorporation in Gate Oxides Using the Resistance to Oxidation Method
Authors: Sagnes I. , Laviale D. , Regache M. , Glowacki F. , Deutschmann L. , Blanchard B. , Martin F.
Published: April 2011

Numerous nitridation processes have been studied to obtain very thin (≤ 6 nm), reproducible and reliable gate oxides. Recent results (1,2,3) have confirmed that i) the NO molecule is the species responsible for the nitrogen incorporation at the SiO2/Si interface and that ii) the direct use of NO gas allows the gate oxide to be nitrided at low thermal budget whilst maintaining the same advantages as those of N2O nitridation. NO nitridation of very thin oxides has so far been inadequately documented in terms of incorporated nitrogen concentration at the SiO2/Si interface. It is of prime importance to control the incorporation of a few nitrogen monolayers at the SiO2/Si interface, particularly for device performances in the 0. 18μm CMOS technology. In the following we present results on the control of low nitrogen concentration in pure NO atmosphere, with particular emphasis on a method based on the re-oxidation of nitrided oxides. This method can be used in a production line thus avoiding the high costs and long characterization times associated with SIMS measurements.
Development of a Cluster Tool and Analysis of Deposition of Silicon Oxide by TEOSO2 PECVD
Authors: Morimoto N. I. , Swart J. W.
Published: April 2011

A single wafer cluster tool was developed. It is composed of a central robot arm wafer handler and three processing chambers: a RF PECVD chamber, a microwave after glow RPECVD chamber and a rapid thermal annealing chamber. The tool is designed to allow high flexibility, with in-situ multi-sequential processing capability. An in depth study of the deposition of silicon oxide by PECVD was performed. As unique features, it handles TEOS vapor without a carrier gas and it includes a double stage gas distribution system. The films were characterized by means of: ellipsometry, FTIRS, RBS, AES, SIMS, stress and etch rate in diluted (1:100) HF solution. Good uniformity (>98 %) was obtained. The results show that the quality of the films is most influenced by the wafer temperature and flux of oxygen. For the best condition, the following results were obtained: deposition rate of 370 nm/min., refraction index of 1.46, stoichiometry of 2.0, intrinsic stress of 1.3×109 dyn/cm2, carbon content below the AES and SIMS detection limit and low OH content. We also propose a model that fits our results.
Low Temperature Oxidation Processing with High Purity Ozone
Authors: Kurokawa A. , Ichimura S. , Kang H. J. , Moon D. W.
Published: April 2011

To lower the temperature of oxide-passivation processing the high- purity ozone (more than 98 mole %) was used instead of usual thermal oxidation. Initial oxide formation on a Si(111) surface with high-purity ozone is investigated by X-ray photoelectron spectroscopy (XPS). From the comparison of the suboxides formed with ozone and oxygen exposures, it is clear that ozone forms less suboxide than oxygen. The oxidation with ozone also proceeds on the hydrogen passivated surface which oxygen molecules do not oxidize.
Wafer Temperature Measurement: Status Utilizing Optical Fibers
Authors: Schietinger Chuck , Jensen Earl
Published: April 2011

This paper reviews the current status and problems of optical fiber temperature measurements for RTP and single wafer processing. Included is a discussion of a range of fiber based options available and currently being utilized today. The advantages and disadvantages of the options are presented. In addition new data from the use of the Ripple Technique pyrometer is presented. Included are data from AT&T (Lucent Technologies) ripple pyrometer development. Lucent Technologies is evaluating and improving the ripple pyrometer on a number of different style production RTP furnaces. Recent advances in signal processing for very low level photo diode currents in the range of 10 e-14 amps, will also be presented.
Commercial RTP-A SEMATECH Perspective
Authors: Speranza Tony , Riley Terry , Nanda Arun , Fowler Burt , Torres Kenneth , Geyling Franz , Lindholm Don
Published: April 2011

This paper discusses various commercial aspects of Rapid Thermal Processing (RTP). It provides an overview of SEMATECH's efforts to improve the manufacturing viability of RTP. Over the past several years SEMATECH, a U.S. Government/Industry consortium, has identified thermal equipment and processing needs relating to semiconductor manufacturing. It has aggressively pursued solutions to these needs through specific equipment projects. These projects include: RTP Installed Base Productivity Improvement, 0.25um RTP Tool Development, and RTP Modeling and Component Technology. Also discussed are several thermal projects which focus on the performance of more traditional tools. A comparison between RTP and a vertical furnace with model based process control and a small batch fast ramp furnace is made. A brief discussion of an RTP gate stack cluster tool project is followed by a review of future thermal processing needs, including 300mm.
Response Surface Technique forEx SituProcess Uniformity Optimization in a Multi-Zone RTP System
Authors: Knutson Karson L. , Cooper Thomas L.
Published: April 2011

Many RTP reactors used in production presently employ single point temperature measurement along with multiple lamp zone control. Optimum zone settings in these systems are known to vary depending on the radiative properties of the wafer and the process. Therefore, tuning the system to meet specifications for a new process is achieved by an operator analyzing metrology results and drawing on experience with the system to determine proper zone settings. It would be desirable to have a technique which can be used to optimize the lamp zone settings in an automatic manner that would be the same for every user. Furthermore, such a technique should be both simple to use and robust. In this work a method is presented which relies on an empirical response surface and an interative computational technique to minimize process variance. The results show that the method works regardless of the process variable being optimized, i.e. temperature, oxide thickness, etc., and that the method relies on no user input.
Sub-Half Micron Elevated SourceDrain NMOSFETS by Low Temperature Selective Epitaxial Deposition
Authors: Sun J. , Bartholomew R. F. , Bellur K. , O'Neil P. A. , Srivastava A. , Violette K. E. , Oztiirk M. C. , Osburn C. M. , Masnari N. A.
Published: April 2011

In this paper we report the first NMOSFETs with elevated S/D selectively deposited by ultra high vacuum rapid thermal chemical vapor deposition (UHV-RTCVD). The deposition process included an in-situ vacuum prebake (750 °C for 10 sec) followed by selective epitaxial growth (SEG) at 800 °C. Si2H6 was used as the silicon gas source instead of the more commonly used SiH4 and SiH2Cl2 in order to achieve high growth rates at low pressure. To prevent nucleation from occurring on insulator surfaces during growth, an etching mechanism was introduced by the addition of Cl2. The gases included 100 sccm of 10% Si2H6 in H2 and 2 sccm of Cl2 at a process pressure of 24 mTorr. An epitaxial growth rate of 160 nm/min has been achieved. The final epi thickness was around 0.1 μm. The S/D junctions were formed via ion implantation into the epi. The subsequent RTA (10 sec at 950 °C) resulted in an effective junction depth about 75 nm beneath the starting Si substrate. Process and device simulations reveal the importance of maintaining a shallow LDD junction for deep submicron devices by using low temperature selective deposition. MOSFETs exhibit good subthreshold characteristics with subthreshold swing of 86 mV/dec at a drain bias of 2.5 V, and threshold variations due to charge sharing and drain-induced-barrierlowering (DIBL) were moderate for Leff down to 0.35 μm. The gate-induced junction leakage current is below 2 pA/μm at a bias of 2.5 V.
Silicon Thin Film Homoepitaxy by Rapid Thermal Atmospheric-Pressure Chemical Vapor Deposition (RT-APCVD)
Authors: Monna Rémi , Angermeier Detlef , Slaoui Abdelilah , Muller Jean Claude
Published: April 2011

The homoepitaxy of thin film silicon layers in a horizontal, atmospheric pressure RTCVD reactor is reported. The experiments were conducted in a temperature range from 900°C to 1300°C employing the precursor trichlorosilane (TCS) and the dopant trichloroborine (TCB) diluted in hydrogen. The epilayers were evaluated by Nomarski microscopy, Rutherford backscattering spectroscopy, and scanning electron microscopy (SEM). The electrical properties of the thin film were analyzed by sheet resistance and four point probe characterization methods. We propose that the responsible mechanisms for the observed growth decline at higher precursor concentration in hydrogen are due to the reaction of the gaseous HCI with the silicon surface and the supersaturation of silicon.
The Effect of Multilayer Patterns on Thermal Stress During Rapid Thermal Processing
Authors: Hebbi Jeffrey P. , Jensen Klavs F.
Published: April 2011

Multilayer patterns can lead to temperature non-uniformity and undesirable levels of thermal stress in silicon wafers during rapid thermal processing (RTP). Thermal stress can, in turn, cause problems such as photolithography overlay errors and degraded device performance through plastic deformation. In this work, the temperature and stress fields in patterned wafers are simulated using detailed finite-element based reactor transport models coupled with electromagnetic theory for predicting radiative properties of multilayers. The temperature distributions are then used to predict the stress fields in the wafer and the onset of plastic deformation. Results are presented for two generic two-dimensional axi-symmetric reactors employing single and double side illumination. The effect of patterns and processing parameters are explored, and strategies for avoiding pattern induced plastic deformation are evaluated.
Microwave Processing of Redox Ceramic-Metal Composites
Authors: Fiore R. R. Di , Clark D. E.
Published: April 2011

Ceramic-metal composites have been produced through the reduction of copper oxide (CuO) and the oxidation of aluminum in a reducing atmosphere. Fine powders of CuO and Al (<38μm) were mixed with yttria stabilized zirconia, ball milled and uniaxially pressed into disc samples. Microwave hybrid heating was used to process samples using β-SiC and activated carbon powder as susceptors. Pyrolysis of the carbon provided the reducing atmosphere. The resulting Ctt/Al2O3/Y-ZrO2 composite was analyzed for density, compressive strength and resistivity.
Microwave Induced Plasma (MIP) Brazing of Silicon Nitride to Stainless Steel
Authors: Samandi M. , Bate M. , Donnan R. , Miyake S.
Published: April 2011

In an attempt to accelerate the process of joining of metals to ceramics, a new rapid brazing technology has been developed. In this process, referred to as Microwave Induced Plasma (MIP) brazing, a microwave plasma is used to rapidly heat the ceramic and metal to the melting temperature of the reactive braze material. The heating rate obtained by MIP could be many times faster than those achieved by conventional resistive heating in a tube furnace. The fast heating rate has no detrimental effect on the joint quality and in fact results in the formation of a thick interfacial film suggesting significant interdiffusion between the braze and ceramic, possibly stimulated by the microwave radiation. In this paper the experimental arrangement of the MIP system is described. The unique capability of the MIP heating is demonstrated by successful joining of hot pressed silicon nitride to stainless steel using reactive metal brazing. The results of microstructural characterisation of the joints carried out by SEM and EDS will also be presented.
Industrial Applications of Variable Frequency Microwave Energy in Materials Processing
Authors: Fathi Z. , Tucker D. A. , Lewis W. A. , Wei J. B.
Published: April 2011

A review of some market-driven research, process applications and systems development is provided. The variable frequency microwave processing concepts are briefly described. Industrial processing using variable frequency microwave energy in the areas of polymerization, composite processing, bonding and plasma is discussed. Analytical applications inherent in the use of variable frequency and its control are demonstrated in the areas of materials signature analysis for volumetric cure monitoring.
Measurements of Dielectric Properties for Intense Heating Applications
Authors: Borrego J. M. , Connor K. A. , Braunstein J.
Published: April 2011

Dielectric measurements for frequencies in the tens of gigahertz are discussed. Interpretation of measurements obtained for mixtures are presented based on some simple analytical models and finite-element analysis of the wave structure in the measurement apparatus.
A Hybrid Numerical Method For Modeling Microwave Sintering Experiments
Authors: Hile C. V. , Kriegsmann G. A.
Published: April 2011

We describe a hybrid numerical method for modeling the electromagnetic interaction of a low-loss material in a single-mode waveguide applicator. The method we propose utilizes a combination of asymptotic and numerical techniques. The interaction between the applicator and the electromagnetic fields is described using scattering matrix theory and the interaction between the electromagnetic fields and the ceramic is determined numerically. Several simulations are presented to show the accuracy and simplicity of this method along with the relatively small amount of computer resources it requires.
Enhanced Computer Modelling for High Temperature Microwave Processing of Ceramic Materials
Authors: Craven M. P. , Cross T. E. , Binner J. G. P.
Published: April 2011

A new software package is described for 2-Dimensional modelling of microwave heating. It is particularly suited to the high temperature heating of ceramics, where electrical and thermal properties are strongly dependent on temperature. The described program, x_tlm, runs under Xwindows, which allows a microwave cavity and its contents to be entered graphically and stored as a schematic diagram. The diagram is automatically converted into a mesh format for simulation using a topology independent Transmission Line Modelling formulation. Temperature dependencies of material properties are specified as polynomial functions of temperature. Surface heat loss by the radiation mechanism, which dominates at higher temperatures, is also introduced into the model.
Microwave-Assisted Ignition
Authors: Bechtold J. K. , Booty M. R. , Kriegsmann G. A.
Published: April 2011

The microwave heating and ignition of a combustible material is modeled and analyzed in the small Biot number and large activation energy regimes. Both the temporal and spatial evolution of the temperature within the material are described. The ignition characteristics are determined by a localized equation for the perturbation to the inert temperature, which is shown to exhibit thermal runaway behavior. Analysis of this local equation provides explicit ignition conditions in terms of the physical parameters in the problem.
Possibility of Microwave-Controlled Surface Modification
Authors: Rybakov K. I. , Semenov V. E.
Published: April 2011

Results of the theoretical study of surface effects in ionic crystalline solids under the action of high-frequency electric fields of moderate intensity are presented. The averaged ponderomotive action of the electric field on the charged vacancies within the crystal causes directional mass transport that leads to development of a surface instability. The analysis shows that the proposed effect can result in the formation of a periodic profile on the surface.
A Comparison Study on the Densification Behavior and Mechanical Properties of Gelcast Versus Conventionally Formed B4C Sintered Conventionally and by Microwaves
Authors: Menchhofer P. A. , Morrow M. S. , Kiggans J. O. , Schechter D. E.
Published: April 2011

This investigation compares microstructures and mechanical properties of both Gelcast B4C and “conventionally” die-pressed B4C, using both microwave and conventional sintering methods. The microstructures and final mechanical properties of B4C specimens are discussed.
Effect of Microwave Treatment on the Bulk and Nearcontact Properties of Semiconductors of Technical Importance
Authors: Belyaev A. A. , Belyaev A. E. , Ermolovich I. B. , Komirenko S. M. , Konakova R. V. , Lyapin V. G. , Milenin V. V. , Tkhorik Yu. A. , Shevelev M. V.
Published: April 2011

We investigated the effect of microwave radiation on the physico-chemical properties of some semiconductor materials (CdxHgl-xTe, GaAs) and metal (Al, Pt, Cr, Mo, W) - GaAs Schottky barrier diode structures. From comparison with the results of the other treatments (heat annealing, g-irradiation) some suggestions are made concerning possible mechanisms of the interaction between microwave radiation and the objects studied.
The Magnetic Field Sensor on the Base of Ybacuo Ceramics with Sharp Jump of Magnetic Reply
Authors: Rostami Kh. R. , Sukhanov A. A. , Mantorov V. V.
Published: April 2011

The magnetic field sensor with sensitivity 10−3 Oe and work temperature 77°K is created on the base of YBaCuO ceramics having a sharp jump of the diamagnetic moment in the region of the first Josephson critical magnetic field. The magnetic field measurement methods and the sensor principle are described. Ways to improve the obtained results are indicated.
Finite-Difference Time-Domain Simulation of Microwave Sintering in A Variable-Frequency Multimode Cavity
Authors: White Mikel J , Dillon Steven F. , Iskander Magdy F. , Kimrey Hal D.
Published: April 2011

There have been recent indications that variable-frequency microwave sintering of ceramics provides several advantages over single-frequency sintering, including more uniform heating, particularly for larger samples. The Finite-Difference Time-Domain (FDTD) code at the University of Utah was modified and used to simulate microwave sintering using variable frequencies and was coupled with a heat-transfer code to provide a dynamic simulation of this new microwave sintering process. This paper summarizes results from the FDTD simulations of sintering in a variable-frequency cavity. FDTD simulations were run in 100-MHz steps to account for the frequency variation in the electromagnetic fields in the multimode cavity. It is shown that a variable-frequency system does improve the heating uniformity when the proper frequency range is chosen. Specifically, for a single ceramic sample (4 × 4 × 6 cm3), and for a variable-frequency range from f = 2.5 GHz to f = 3.2 GHz, the temperature distribution pattern was much more uniform than the heating pattern achieved when using a single-frequency sintering system at f = 2.45 GHz.
Some Aspects Related to The Transfer of Microwave Sensing Technology
Authors: Bolomey J. Ch.
Published: April 2011

This paper reviews the major concerns related to the development of microwave sensing techniques. For their practical importance, testing and measurement of conveyed products via microwave multipoint sensors are more particularly considered. After reporting some promising sensing configurations and applications, technical and non technical aspects involved in the development of microwave sensors are analysed. Some of these aspects are encountered in any technology transfer process, while some others are more particularly specific to microwave sensors. In the conclusion, some general guidelines are provided for a successfull development of microwave sensing technology.
Advanced Ceramics Sintering Using High-Power Millimeter-Wave Radiation
Authors: Setsuhara Y. , Kamai M. , Kinoshita S. , Abe N. , Miyake S. , Saji T.
Published: April 2011

The results of ceramics sintering experiments using high-power millimeter-wave radiation are reported. Sintering of silicon nitride with 5%Al2O3 and 5%Y2O3 was performed in a multi-mode applicator using a 10-kW 28-GHz gyrotron in CW operation. It was found that the silicon nitride samples sintered with 28 GHz radiation at 1650'C for 30 min reached to as high as theoretical density (TD), while the conventionally sintered samples at 1700°C for 60 min resulted in the density as low as 90% TD. Focusing experiments of millimeter-wave radiation from the high-power pulsed 60-GHz gyrotron have been performed using a quasi-optical antenna system (two-dimensional ellipso-parabolic focusing antenna system) to demonstrate the feasibility of the power density of as high as 100 kW/cm2. Typical heating characteristics using the focused beam were made clear for this system. It was found that the densification of yttria-stabilized zirconia (ZrO2-8mol%Y2O3) samples to as high as 97% TD was obtained from the sintering with focused 60 GHz beam in pulse operation with a 10-ms pulse duration at a 0.5Hz repetition. The densification temperature for the zirconia could be lowered by 200°C than that expected conventionally.
Microwave Plasma Assisted CVD of Diamond on Titanium and Ti-6Al-4V
Authors: Tucker D. A. , McClure M. T. , Fathi Z. , Sitar Z. , Walden B. , Sutton W. H. , Lewis W. A. , Wei J. B.
Published: April 2011

The ultimate goal of this research was to demonstrate a Microwave Plasma assisted Chemical Vapor Deposition (MPCVD) process to coat a Ti-6A1-4V bearing shaft. Preliminary experiments were performed in an ASTeX™ system on flat chemically pure titanium and Ti-6AI-4V coupons. Diamond deposition was also attempted on a Ti-6AI-4V wedge sample which contained a curved surface that simulated the bearing. Although uniform diamond deposition was attained on the flat samples, very poor uniformity was observed on the curved sample. This lack of uniformity was attributed to the difficulty in controlling the plasma-to-substrate distance in a single mode, single frequency reactor and it was believed that by varying the frequency and using a multimode cavity one could solve this problem. Thus, depositions on a titanium rod were performed in a variable frequency MPCVD reactor. It was determined visually that the variable frequency operation provided uniform plasma distribution along the length and circumference of the rod and resulted in a fairly uniform coating. However, scanning electron microscopy revealed that the morphology of the particles was poor and micro-Raman spectroscopy showed weak, broad peaks that were attributable to amorphous carbon. It is believed that by fine-tuning parameters, a uniform diamond film of good quality can be achieved along the entire rod.
New 915 MHz Low Power Generator for Materials Testing Utilizing an Evanescent Mode Cavity
Authors: Buffler Charles R. , Risman Per O.
Published: April 2011

The economy of utilizing 915 MHz vs. 2450 MHz microwave equipment has long been acknowledged for many industrial processes. A severe roadblock to advancing 915 MHz processing has been the lack of proper equipment to run test trials. At 2450 MHz low power equipment is readily available and inexpensive, even resorting to the use of the consumer microwave ovens. At 915 MHz, however, prototyping systems have only been available using very expensive 5 kW magnetrons. Experimenters have been forced to use 2450 MHz low power equipment to explore scale-up potential for high power 915 MHz systems. Because of wavelength and dielectric property differences, this procedure may give highly erroneous results, sometimes leading to the purchase of production equipment which does not work.

This paper describes an inexpensive, low power, microwave system for prototype testing at 915 MHz. A 600 watt generator is coupled to a specially designed evanescent mode applicator/cavity for the trial testing prior to making a scale-up decision. A description of the generator and evanescent cavity design are presented.
Microwave Firing At 915 MHz - Efficiency and Implications
Authors: Evans N. G. , Hamlyn M. G.
Published: April 2011

The conversion efficiency of electrical to microwave power by magnetrons operating at 896 / 915 MHz is significantly greater than that of magnetrons operating at 2.45 GHz. The increased efficiency at this frequency improves the prospects of microwave firing being adopted as a commercially viable process but the change in frequency alters the microwave-material interactions that take place.

This paper discusses the influence and implications of using 896 / 915 MHz for firing ceramics and compares dielectric property data at both frequencies. The results suggest that using the lower frequency will result in more efficient heating.
Microwave Skin Effect in Noncontact Photoconductivity Decay Measurements in Si Wafers
Authors: Ogita Y. , Takahashi S.
Published: April 2011

A formula to calculate the photoconductivity decay curve influenced by the microwave distribution within a silicon wafer has been derived analytically. The difference of photoconductivity decay curves measured at 500 MHz and 10 GHz has been explained by the skin effect and by the comparing the experimental curves to those estimated by the analytical formula. The wafer resistivity and wafer thickness dependent photoconductivity decay curves calculated based on the skin effect have been demonstrated. The results have led to the conclusion that 10 GHz microwave probe scarcely influences on the photoconductivity decay for the silicon wafer with the resistivity >10 Ωcm and a wafer thickness <0.7 mm. For the wafer with a resistivity<10 Ωcm and a wafer thickness>0.7 mm, the photoconductivity decay curve is influenced by the skin effect at 10 GHz. However, the apparent lifetime (or effective lifetime) obtained from the gradient of the tail decay is out of the influence by the microwave skin effect.
Effect of Argon Ion Bombardment on the Stability of Narrow Cobalt Silicide/Polysilicon Structure
Authors: Maa Jer-Shen , Peng Chien-Hsiung
Published: April 2011

The stability of cobalt silicide formed on narrow polysilicon line degraded rapidly with shrinkage of linewidth as shown by the increase of sheet resistance after annealing. Stability was improved by adding a titanium interlayer under cobalt with or without a Ti or TiN cap layer. The stability was affected by silicide thickness and substrate doping. In best cases an increase of sheet resistance after annealing was still observed. Adding an Ar ion bombardment step improved the thermal stability drastically. This structure did not show any sheet resistance change after a 30 min annealing at 850°C, either with or without interlayer or cap layer.
Modeling of Extended Defects in Silicon
Authors: Law M. E. , Jones K. S. , Earles S. K. , Lilak A. D. , Xu J- W.
Published: April 2011

Transient Enhanced Diffusion (TED) is one of the biggest modeling challenges present in predicting scaled technologies. Damage from implantation of dopant ions changes the diffusivities of the dopants and precipitates to form complex extended defects. Developing a quantitative model for the extended defect behavior during short time, low temperature anneals is a key to explaining TED. This paper reviews some of the modeling developments over the last several years, and discusses some of the challenges that remain to be addressed. Two examples of models compared to experimental work are presented and discussed.
The Effect of Temperature on Defect Production by Displacement Cascades in alpha;-IRON
Authors: Gao F. , Bacon D. J. , Flewitt P. E. J. , Lewis T. A.
Published: April 2011

Molecular dynamics (MD) simulations have been used to study the number and arrangement of defects produced by displacement cascades as functions of irradiation temperature, Tirr, in α-iron. The continuum treatment of heat conduction was used to adjust the temperature of the MD boundary atoms throughout the cascade process. This new hybrid model has been applied to cascades of either 2 or 5 keV at 100K, 400K, 600K and 900K. The number of Frenkel pairs decreases by about 20–30% as Tir increases from 100K to 900K, due to the increase in the lifetime of the thermal-spike phase. The same effect also brings about an increase in the proportion of selfinterstitial atoms that form clusters.
Transmission Electron Microscopy Study In-Situ of Radiation-Induced Defects in Copper at Elevated Temperatures
Authors: Daulton T. L. , Kirk M. A. , Rehn L. E.
Published: April 2011

Neutrons and high-energy ions incident upon a solid can initiate a displacement collision cascade of lattice atoms resulting in localized regions within the solid containing a high concentration of interstitial and vacancy point defects. These point defects can collapse into various types of dislocation loops and stacking fault tetrahedra (SFT) large enough that their lattice strain fields are visible under diffraction-contrast imaging using a Transmission Electron Microscope (TEM). The basic mechanisms driving the collapse of point defects produced in collision cascades is investigated in situ with TEM for fcc-Cu irradiated with heavy (100 keV Kr) ions at elevated temperature. The isothermal stability of these clusters is also examined in situ.

Areal defect yields were observed to decrease abruptly for temperatures greater than 300°C. This decrease in defect yield is attributed to a proportional decrease in the probability of collapse of point defects into clusters. The evolution of the defect density under isothermal conditions appears to be influenced by three different rate processes active in the decline of the total defect density. These rate constants can be attributed to differences in the stability of various types of defect clusters and to different loss mechanisms. Based upon observed stabilities, estimations for the average binding enthalpies of vacancies to SFT are calculated for copper.
High Resolution Transmission Electron Microscopy of Defect Clusters in Aluminum During Electron and Ion Irradiation at Room Temperature
Authors: Furuya Kazuo , Piao Min , Ishikawa Nobuhiro , Saito Tetsuya
Published: April 2011

Defect clusters in Al during electron and ion irradiation have been investigated using highresolution transmission electron microscopy (HRTEM). An ION/HVEM system which consists of a high-voltage TEM and ion implanters was used for in-situ observation of damage evolution under 1000 keV electrons and 15 keV He+ irradiation at room temperature. HRTEM of Al in [110] orientation showed many planar defects along { 111 } planes during electron irradiation, while a high density of small polyhedron-shaped cavities (He-bubbles) was observed in addition to the planar defects after He+ irradiation. Multi-slice image simulation of various models of dislocation loops indicated the planar defect as an interstitial-type Frank loop.
Computer Simulation of the Migration Of Self-Interstitial Atoms in Alpha-Zirconium
Authors: Whiting B. J. , Bacon D. J.
Published: April 2011

The migration of single interstitials and small interstitial clusters in ox-zirconium at different temperatures has been analysed using a molecular dynamics model with a many-body interatomic potential. The migration exhibits a strong anisotropy. The defects are very mobile (with Em = 0. 01 eV) along <1120> directions in the basal plane, and this motion is dominant for the single interstitial at low temperature and the di- and tri-interstitials at all temperatures. Above about 500 K, the single interstitial exhibits 2-D and 3-D motion, but Em for non-basal motion is about 0.133 eV. These results point to important consequences for the behaviour of defects formed by displacement cascades in irradiated zirconium.
Mixing of Al Into Uranium Silicides Reactor Fuels
Authors: Ding Fu-Rong , Birtcher R. C. , Kestel B. J. , Baldo P. M.
Published: April 2011

SEM observations have shown that irradiation induced interaction of the aluminum cladding with uranium silicide reactor fuels strongly affects both fission gas and fuel swelling behaviors during fuel burn-up. We have used ion beam mixing, by 1.5 MeV Kr, to study this phenomena. RBS and the 27 A1( p, γ) 28 Si resonance nuclear reaction to was used to measure radiation induced mixing of Al into U3Si and U3Si2 after irradiation at 300γ;C.

Initially U mixes into the Al layer and Al mixes into the U3 Si. At a low doses, the Al layer is converted into Ual4 type compound while near the interface the phase U(Al93 Si. 07 )3 grows. Under irradiation, Al diffuses out of the Ual4 surface layer, and the lower density ternary, which is stable under irradiation, is the final product. Al mixing into U3 Si2 is slower than in U3 Si, but after high dose irradiation the Al concentration extends much father into the bulk. In both systems Al mixing and diffusion is controlled by phase formation and growth. The Al mixing rates into the two alloys are similar to that of Al into pure uranium where similar aluminide phases are formed.
Modeling Amorphization of Tetrahedral Structures Using Local Approaches
Authors: Jesurum C. Esther , Pulimt Vinay , Berger Bonnie , Hobbst Linn W.
Published: April 2011

Many crystalline ceramics can be topologically disordered (amorphized) by disordering radiation events involving high-energy collision cascades or (in some cases) successive single-atom displacements. We are interested in both the potential for disorder and the possible aperiodic structures adopted following the disordering event. The potential for disordering is related to connectivity, and among those structures of interest are tetrahedral networks (such as SiO2, SiC and Si3N4) comprising corner-shared tetrahedral units whose connectivities are easily evaluated. In order to study the response of these networks to radiation, we have chosen to model their assembly according to the (simple) local rules that each corner obeys in connecting to another tetrahedron; in this way we easily erect large computer models of any crystalline polymorphic form. Amorphous structures can be similarly grown by application of altered rules. We have adopted a simple model of irradiation in which all bonds in the neighborhood of a designated tetrahedron are destroyed, and we reform the bonds in this region according to a set of (possibly different) local rules appropriate to the environmental conditions. When a tetrahedron approaches the boundary of this neighborhood, it undergoes an optimization step in which a spring is inserted between two corners of compatible tetrahedra when they are within a certain distance of one another; component forces are then applied that act to minimize the distance between these corners and minimize the deviation from the rules. The resulting structure is then analyzed for the complete adjacency matrix, irreducible ring statistics, and bond angle distributions.
Electron-Irradiation-Induced Crystallization of Amorphous Orthophosphates
Authors: Meldrum A. , Boatner L. A. , Ewing R. C.
Published: April 2011

Amorphous LaPO4, EuPO4, GdPO4, ScPO4, LuPO4, and fluorapatite [Ca5(PO4)3F] were irradiated by the electron beam in a transmission electron microscope. Irradiations were performed over a range of temperatures from −150 to 300 °C, electron energies from 80 to 200 keV, and current densities from 0.3 to 16 A/cm2. In all cases, the materials crystallized to form a randomly oriented polycrystalline assemblage. Crystallization is driven dominantly by inelastic processes, although ballistic collisions with the target nuclei can become important at energies higher than 175 keV, particularly in apatite. Using a high current density, crystallization is so fast that continuous lines of crystallites can be “drawn” on the amorphous matrix.
Atomic Sites of Isolated 111In Atoms After Low Energy Deposition on Stepped Cu(100) Surfaces
Authors: Laurens C.R. , Roşu M.F , Pleiter F. , Niesen L.
Published: April 2011

We deposited low-energy 111 atoms on a vicinal Cu(100) surface at 82K, and measured the atomic sites by means of the perturbed angular correlations technique (PAC). The sites of the as-deposited In atoms were determined for deposition energies ranging from 5 to 100 eV. The results are coinpared to Molecular Dynamics simulations of the deposition process.
Simulation of Surface Diffusion Using Embedded Atom Potentials in FCC Metals
Authors: Takano Jun-Ichiro , Doyama Masao , Kogure Yoshiaki
Published: April 2011

The binding energies of gold, silver and copper adatoms and their clusters to each (111) surface have been calculated. The binding energy EN of an N-adatom cluster can be roughly written as EN=3NE1+mE2, where 3E1, is the binding energy of a single adatom to the (111) surface and m is the number of bonds within the cluster and E2 is the binding energy of the bond within the cluster. It was found that E1=0.95eV, E2=0.42–0.49eV for gold, E1=0.62eV, E2=0.38-0.44eV for silver and E1=0.81eV, E2=0.43–0.49eV for copper (by use of a newly determined N-body embedded atom potential). The activation energies of motion of these adatom clusters on each (111) surfaces have been calculated by use of a newly determined N-body embedded atom potential and molecular dynamics method.
The Structure of Antigen-Antibody Layers Adsorbed on Silica Surfaces: a Scanning Angle Reflectometry Study
Authors: Mann E. K. , Heinrich L. , Voegel J. C. , Schaaf P.
Published: April 2011

Scanning Angle Reflectometry (SAR) is used to investigate the structure of protein layers deposited sequentially, first the antigen and then the antibody, on a silica surface. The reflectivity curves are analyzed by means of the optical invariants, a general description valid in the thin film limit which permits the determination of three and only three structural parameters for a dielectric layer, independent of any model of the layer. The three parameters can be related to the first two moments of the mass density in the layer, or to an average film thickness and density. In addition, a new invariant is constructed which directly yields information about the distribution of mass in the layer, and thus goes beyond the usual uniform layer model.
Processing Temperature Dependence on Surface Morphology and Microstructure of Gold Films
Authors: He L. , Siewenie J. , Shi Z. Q.
Published: April 2011

Microstructure properties, and surface morphology of gold films processed at different temperature were investigated by transmission electron microscopy (TEM) and atomic force microscope (AFM). The film thickness was chosen less than several hundreds angstrong. Previous electrical measurement found that the low temperature (LT=77K) film showed several orders lower resistance compared to the film obtained at room temperature with very thin (about 100Å) thickness. This indicated potential application of these LT films on electronic and optoelectronic devices. TEM study found that the LT films showed much smaller density of grain boundaries than that of the room temperature (RT=300K) samples. In AFM observation, for film thickness of 100Å, LT film showed smoother, and continuous surface while the RT film consisted of discrete islands. When the thickness was increased to 200Å, the LT film showed much larger-sized grains compare to that of the RT film. For LT deposition, 2-dimensional larger-sized grains were first formed at low temperature deposition which later extended to be 3-dimension. The low grain boundary density of the LT film is consistent with its lower resistivity observation.
Studies of Interface and Surface Structures of BaTiO3 Thin Films Grown on SrTiO3 (001) Substrates by Mbe
Authors: Shigetani Hisashi , Kobayashi Kazuyoshi , Fujimoto Masayuki , Sugimura Wataru , Matsui Yoshio , Tanaka Junzo
Published: April 2011

We studied a lattice distortion and relaxation of BaTiO3(BT) thin films grown on SrTiO3 (001) substrates(ST) by a molecular beam epitaxy method using an oxygen radical source RT were prepared by alternately deposition of BaO and TiO2 layers, and the structure of the thin films was evaluated by X-ray diffraction, reflection high energy electron diffraction, transmission electron microscopy, atomic force microscopy, coaxial impact collision ion scattering spectroscopy and X-ray photoelectron spectroscopy The lattice constants of the films varied with distance from the interface of BT and ST It was found that lattice distortion and relaxation of BT On the other hand, the surface analysis indicated that adsorbed oxygen was enriched on the BaO-terminated surface in comparison with the TiO2-terminated surface Then we proposed new mechanism of BT thin film growth with adsorbed oxygen.
Microelectronic Film Thickness Determination Using a Laserbased Ultrasonic Technique
Authors: Logan R. , Maznev A. A. , Nelson K. A. , Rogers J. A. , Fuchs M. , Banetv M.
Published: April 2011

A non-contact and non-destructive laser-based acoustic technique called impulsive stimulated thermal scattering (ISTS) is used to measure thicknesses of films in single-layer and multilayer assemblies such as W/Si, Ti/Si, and Ti/SiO2/Si structures. Thicknesses are determined to within a few percent accuracy with a laboratory version of the measurement apparatus, using conventional large-frame lasers and optics, and in a commercial prototype using compact diode-pumped and diode lasers and optics which all fit onto a 1-ft × 2-ft breadboard. ISTS and conventional measurements (profilometry, SEM, and 4-point resistance) are made on the same samples and the results are found to compare favorably.
Structure of Kcn Monolayer Films Vapor-Deposited onto Cleaved KBr(001) by Helium Atom Diffraction
Authors: Safron S. A. , Baker J. R. , Lit J. A. , Akhadov E. A. , Trelenberg T. W. , Skofronick J. G.
Published: April 2011

Angular distribution measurements of the helium atom scattering intensity from monolayer films of KCN/KBr(001) for several azimuths over a temperature range of approximately 40–200 K reveal that above ˜95 K the KCN monolayer forms a (1×1) overlayer structure with respect to the KBr substrate. (The lattice spacing of bulk KCN in the rocksalt-structure phase differs from that of KBr by only ˜ 1%.) Below this temperature the overlayer appears to be (2×1), and “missing” diffraction spots in the <110> high symmetry direction suggest the existence of a glide plane. The inferred structure for this low temperature phase consists of K+ ions fixed in their rocksaltstructure positions relative to the substrate and the CN− ions oriented so that their dipoles are aligned antiferroelectrically within the new unit cell.
Surface Structure Determination of C(2×2) N2/Ni(100) and Low and Intermediate Coverages of Co/Cu(111) by Angle-Resolved Photoemission Fine Structure (Arpefs) Using Synchrotron Radiation
Authors: Moler E. J. , Huff W. R. A. , Kellar S. A. , Hussain Z. , Chen Y. F. , Shirley D. A.
Published: April 2011

We have determined the adsorption site and interlayer spacings of c(2×2) N2/Ni(100),(√3 × √3)R30° and (1.5 × 1.5)R18° CO adsorbed on Cu(111), using ARPEFS and a full Multiple-Scattering, Spherical Wave (MSSW) calculation program. The nitrogen molecule stands upright at an atop site, with a N-Ni bond length of 2.25(1) Å, a N-N bond length of 1.10(7) Å, and a first layer Ni-Ni spacing of 1.76(4) Å. The C-Cu bond length is 1.91 (1) Å in the (√3 × √3)R30° phase and 1.91(2) Å in the (1.5 × 1.5)R18° phase. The first layer Cu-Cu spacing is 2.07(3) Å in the (√3 × √3)R30° phase. The first layer Cu-Cu spacing in the (1.5 × 1.5)R18° phase is 2.01(4) Å, a contraction of 3 % from the clean metal value of 2.07 Å.