bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of pH on CMP of VOx Thin Films for RRAM
Authors: Liguo Yin , Zhang Kailiang , Fang Wang , Wei Xiaoying , Taofeng Zhang
Published: March 2011

Resistive random access memory has attracted enormous attention as next generation high density nonvolatile memory for flash memory, due to its low voltage operation, high programming speed, and simple fabrication. And Chemical mechanical planarization technology of the novel memory materials is also the necessary work for its application in RRAM devices, especially for TiO2、 NiO and VOx films which are the focused RRAM materials recently. In this paper, CMP of VOx films was investigated firstly, and the effect of slurry pH on MRR and surface roughness was discussed. MRR results show that high polishing rates can be observed with low pH (acidic slurry) and high pH (alkaline slurry), which are more than 250 nm/min. However, lower surface roughness can be achieved only when alkaline slurry was used (0.12 nm vs 2.6 nm). In conclusion, the alkaline slurry with silica abrasives is the optimum candidate for CMP of VOx films.
Study of Inhibition effects on Copper CMP Slurry Performance
Authors: Jing Jianfen , Ma Zhiyong , Li Pei , Lu Chen , Lin Paulchang , Zhang Jian , Cai Xinyuan
Published: March 2011

With the development of the products with more advanced technology nodes, new challenges continue to emerge in CMP processes. For example, there is a strong need to use lower down force in polishing process while maintaining a high removal rate to avoid low-k/ultra-low k dielectric film damage. The requirements for dishing, overpolish window, Cu residue clearance capability and surface defectivity, especially corrosion related defects become more stringent as copper lines become narrower and narrower. In this paper, we share our research efforts and results in developing a novel copper CMP slurry to overcome these performance challenges in Cu CMP process. In short, a well designed inhibitor system was applied in this slurry. The impacts of these inhibitors on the slurry performance including blanket removal rate/profile, static etch rate, dishing, Cu residue clearance capability and corrosion were evaluated through polishing experiments, electrochemistry evaluations, and laboratory tests simulating CMP aggressive conditions. With a synergetic effect of these inhibition systems, the slurry shows the excellent CMP performance
SiON Gate Dielectric Optimization for NBTI Improvement
Authors: Chen Yong , He Yonggen , Wang Wenbo , Guo Rita , Tang Zhaoyun , Liu Jialei , Wu Jingang , Ju Jianhua
Published: March 2011

Plasma nitride SiON films have been widely used as gate dielectric in advanced CMOS device fabrication since 90nm technology node. As a replacement material for conventional silicon dioxide, it can provide increased dielectric constant and serve as an effective boron barrier. Post nitridation anneal (PNA), a critical step for plasma nitride SiON formation, is used to stabilize plasma incorporated nitrogen radicals and ions through form thermal stable Si-N banding. Furthermore, PNA can repair the damaged Si/SiO2 interface by interface substrate re-oxidation under oxygen contained ambient. In this work, several PNA conditions were studied. Their effect on transistor performance and PMOS NBTI (Negative Bias Temperature Instability) lifetime were evaluated. It demonstrates that NBTI performance can be improved 20% by PNA process optimizing, while keeping the same Tinv thickness and Ioff/Ion performance.
eSiGe Global and Micro Loading Effect Study in High Performance 45nm CMOS Technology
Authors: He Yonggen , Tu Huojin , Lin Jing , Song Hualong , Wang Jun , Ma Guiyin , Xu Weizhong , Ye Bin , Yu Tzuchiang , Wu Jingang
Published: March 2011

The embedded silicon germanium (eSiGe) is widely applied in advanced CMOS device fabrication to boost PMOS channel mobility. Beside selectivity, defect control and thermal compatibility, one big challenge of epitaxy growth SiGe process is loading effect between different product and different features. In this work, two precursors of SiH4 and SiH2Cl2 (DCS) were applied for SiGe epitaxy growth respectively. Their impact on embedded silicon germanium global and micro loading was investigated also. The results reveal some solutions to minimize the loading effect such as proper precursor selection, partial pressure optimization and silicon open space constraint.
Investigation of Laser Spike Anneal Dwell Time and It's Compatibility with Embedded-SiGe
Authors: He Yonggen , Chen Yong , Lu Jiongping , Wu Jingang , Xu Chuanjin , Yu Tzuchiang , Owen David M. , Zhang Yun , Shetty Shrinivas
Published: March 2011

Laser spike anneal (LSA) is applied in advanced CMOS device fabrication to achieve efficient dopant activation without excess dopant diffusion. Dwell time, defined as the ratio of full width at half maximum of laser beam and beam scan speed, is found to be a critical and effective knob in LSA processes. In this work, different dwell time of LSA and its impact on dope activation, junction profile, and compatibility with embedded SiGe (e-SiGe) was studied. Dwell time in the range of 800us to 275us has been investigated. LSA processes with different dwell time result in similar dopant activation and almost identical doping profile. On the other hand, reduced dwell time resulted in significant improvement in wafer warpage and overlay performance, when LSA is applied on CMOS devices with e-SiGe S/D pMOSFET. With electrical results consistent with offline characterization, this work indicated that lower dwell time LSA is more flexible and compatible with e-SiGe process for advanced CMOS devices.
A Robust Shallow Trench Isolation High Density Plasma Chemical Vapor Deposition Void Free Process for 0.13μm CMOS Technology
Authors: Ning Grace , Lin Paulchang , Xing Charles , Bian Allen , Zhao Hong-Bo , Cao Ya-Lu
Published: March 2011

Shallow Trench Isolation(STI) is widely used in advanced CMOS technologies. This paper describes a shallow trench isolation for 0.13μm CMOS technologies development which utilizes AMAT Ultima Plus High Density Plasma (HDP) CVD oxide process to fill 0.18μm wide and 0.5μm deep trenches with void free. Through optimizing source/bias RF power, process gas flow and cross section verification, as a result, we got a robust gap-fill recipe with void free.
CMP-Less Planarization Technology with SOG/LTO Etchback for Low Cost 70nm Gate-Last Process
Authors: Yin Huaxiang , Men Lingkuan , Yang Tao , Xu Gaobo , Xu Qiuxia , Zhao Chao , Chen Dapeng
Published: March 2011

A novel 70nm gate-last process featuring with CMP-less spin-on glass/low-temperature oxide (SOG/LTO) etchback method for developing high performance low cost logic platform is demonstrated. The special 3-step sacrificial etchback process all in one RIE chamber is developed to realize the pseudo global planarization on the composite SOG/LTO 2-layer structure. The finally fabricated PMOSFETs demonstrate nice electrical characteristics as well as similar uniformity distribution to that of planarization process.
Etch and Wet Clean Challenges and Joint Optimization
Authors: Yen Bi-Ming , Lin Johnny , Lee Chris , Hegarty Mike , Loewenhardt Peter
Published: March 2011

The emergence of new integration schemes and materials for advanced technology nodes has presented greater challenges to both etch and post etch wet clean. The mutual interactions between etch and clean processes must be considered, thus having both etch and clean process optimized together has become more essential and beneficial in order to provide the optimized process solution.
Growth and Processing Defects in CMOS Homo- and Hetero-Epitaxy
Authors: Simoen Eddy , Bargallo Gonzalez Mireia , Eneman Geert , Rosseel Eric , Hikavyy Andriy Y. , Kobayashi D. , Loo Roger , Caymax Matty , Claeys Cor
Published: March 2011

The impact of different processing steps on the electrical properties of homo- and hetero-epitaxial junctions deposited on silicon substrates is described. In particular, the influence of the pre-epi in situ cleaning, using a high temperature bake in H2 is investigated. It is shown that the removal of oxygen and carbon from the starting surface is crucial in obtaining high-quality, low-leakage epitaxial junctions. In addition, it is demonstrated that post-epi implantation and anneal should be carefully optimized in order to maintain the strain in SiGe layers and to control the defect formation.
Improving Yield with High-Performance Cables
Authors: Warren Paul
Published: March 2011

In the competitive solar and semiconductor industries, high manufacturing yields are very important. The type of cable system used with manufacturing equipment plays an important role in ensuring reliable performance, yet the impact of the cable system is often overlooked during the design process. Cable chain systems can affect yield in two ways: they have a direct impact on the equipment's precision, and they can increase particulation in cleanroom environments. Testing has indicated that eliminating the use of cable chains improved precision and reduced particulation.
Microstructural Evolution of Sn3.0Ag0.5Cu3.0Bi0.05Cr/Cu Solder Joints During Thermal Aging and Its Effects on Mechanical Properties
Authors: Lin Fei , Bi Wenzhen , Ju Guokui , Wei Xicheng
Published: March 2011

The evolution of IMCs in SACBC/Cu solder joint and its tensile property after isothermal aging at 150 ° for 0, 168 and 500 h were investigated. The hollow blocky phase containing Cr was observed in the solder matrix of the joint after soldering, which was not found after aging. The needle-like Ag3Sn transformed to be short rod-like or ellipsoidal during aging. Bright and sphericized Bi particles precipitate at the interface and suppress overgrowth of IMCs layer, resulting in a relative stable tensile strength.
Study of EMC for Cu Bonding Wire Application
Authors: Takeda Toshiro , Seki Hidetoshi , Itoh Shingo , Zenbutsu Shin-ichi
Published: March 2011

The influence of EMC (Epoxy Molding Compound) and reliability with fine Cu wire was studied. It is found that the failure mode was corrosion at the intermetallic layer of the wire bonding part by failure analysis after HAST (Highly Accelerated Temperature & Humidity Stress Test). Al elution and Cl ion was observed at the intermetallic layer. EMC with lower Cl ion content and Al inhibitor of corrosion shows better HAST property. The selection of flame retardant for green EMC is important because some retardant has a negative impact on HAST performance.
Corrosion of Gold and Copper Ball Bonds
Authors: Breach Christopher D. , Ng Hun Shen , Lee Teck Kheng , Holliday Richard
Published: March 2011

Gold and copper ball bonds were isothermally aged under moist conditions (85°C and 85% relative humidity (RH)) and wet conditions (85°C in DI water with and without NaCl) in an effort to better understand the corrosion mechanisms that operate under moist and wet conditions. The objective of this work is to undertake and report on the initial stages of a research project that aims to compare the performance and assess the performance limits of gold and copper ball bonds.
Multi Beam Grooving and Full Cut Laser Dicing of IC Wafers
Authors: Borkulo Jeroen V. , Hendriks Rene
Published: March 2011

Since wafer technologies have dropped below 90nm node and low k materials were introduced it became clear that blade dicing evolution came to an end and expensive hybrid solutions were required to achieve the desired product reliability. Similar situations have been seen with the ongoing trend to thinner wafer that are needed for 3D packaging. To achieve sufficient mechanical strength, complex dicing technologies and sequences have been introduced which do not respond to the requirements for current and near future technologies. This paper will discuss the multiple beam laser dicing technology, an enabling technology that allows semiconductor manufacturers to execute the technology roadmap and continue to comply to Moore's law in an efficient manner. The paper will demonstrate how challenges have been addressed using the multi beam technology. The multiple beam laser dicing technology has already been widely adopted by several other semiconductor technologies and has a proven track record.
Plasma Cleaning Effect on Automotive Devices
Authors: Chew Pei Yi , Aw Tiam Ann
Published: March 2011

In today's semiconductor market of the growing automotive industry, reliability of the devices becomes a major concern as all these devices require an extremely low stress and high thermal condition. This paper will discuss the critical characteristics that are responsible for the die top corner delamination and focuses mainly on a few key areas such as molding compound, wafer and plasma cleaning process so as to enable the achievable of reliable and robust package for automotive products. The devices are to be characterized with scanning acoustic tomography (SAT) and various package level reliability tests. From the study, it has been found that plasma cleaning process plays an important role in resolving the reliability issue by totally eliminating die top corner delamination, and which has improved tremendously in the life span of the devices and also the reliability of the packages.
IDDQ Test Practice in Nanotechnologies
Authors: Ye Samuel X. , Shen Clayton , Liu Zhe , Liyun Qin
Published: March 2011

As semiconductor wafer process technology went into nanotech level, IDDQ test faced tremendous challenges than it ever did due to high intrinsic leakage. A case study of IDDQ test in Availink ASICs in 130nm and 65nm process technologies demonstrates that IDDQ test is still feasible. The scheme includes IDDQ test vectors precise selection/generation, IDDQ measurement with high resolution/repeatability, proper statistical post processing algorithm in outlier detection, results verification, etc. As a result, IDDQ test is still considerable in manufacturing test strategy in nanotechnologies era.
Determining Coherence length of X-ray Beam Utilizing Line Grating Structures
Authors: Lee Hae-Jeong , Soles Christopher L. , Wu Wenli
Published: March 2011

Specular x-ray reflectivity has been used successfully to measure the cross section of periodic nanopatterns on flat substrates and in most of the cases the effective medium approximation is found to be adequate for the data analysis. To examine the validity of EMA the coherence length of the X-ray reflectometer was measured quantitatively by extending the scheme used by Salditt et al. A series of linear grating structures with periodicities ranging from 300 nm to 16 µm was studies at various azimuthal angles between the incident X-ray and the lines. A clear break down of EMA was noticed at certain X-ray incident angle depending on the azimuthal angle, this provides a useful pathway for determining the coherent length of the X-ray reflectometer more precisely.
Improvement of In-line SCD Metrology on BEOL Copper CMP Erosion Layers for 65nm Technology Node Logic Production Application
Authors: Rong Clear , Wang Zhigao , Yin Zhengchao , Tan Zhengquan , Zhao Lei
Published: March 2011

Erosion Cu (Copper) interconnect monitor of BEOL (Back End of Line) CMP (Chemical Mechanical Polishing) is a series of key steps for producing high yield Integrated Circuits. For years, ultrasonic was applied to Cu in-line measurement. However, do we have an alternative? In this paper, new solution by the theory of scatterometry was proposed, it is called SCD (Scatterometry CD) metrology. To demonstrate the performance of SCD, multiple layers of Logic 65nm production, from Metal 2 to Metal 5, were developed by SCD and point to point matching with baseline tool were qualified. Furthermore, DOE (Design of Experience) have been employed to verify correlation among SCD, ultrasonic and TEM (Transmission Electron Microscopy). Finally, SCD is proven to be the reliable, high throughput and non-destructive solution of Cu line monitor.
Study The Mixed-Mode Delamination of The Epoxy/Cu Interface
Authors: Liu Yu , Wang Jun
Published: March 2011

The high density packaging, e.g. stacked die packages et al., includes interfaces between different materials. The device reliability is heavily related to the behavior of the interfaces. For instance, the delamination may propagate along dissimilar material interfaces and lead to electrical failure during the package manufacturing, testing processes and even in working state under severe environmental conditions. The interfaces between the epoxy-based composites and copper may be critical due to the large CTE mismatch of the materials. The interface fracture exhibits mixed-mode that combined with mode-I and model-II fractures. In this work, we designed the sandwich samples and a new apparatus to characterize the interface fracture of the epoxy/Cu interface. The sample can be loaded in different angles. The energy release rate and mode mixity were obtained upon the experimental results by the mixed-mode elastic fracture analysis. The method can be applied for other interface characterization in the packaging.
Investigation of Lateral Die Crack Failure at Reliability Test
Authors: Soh Yuen Chun , Tan Chin Meng Jimmy , Chen Xin , Chua Kok Yau , Du Ruomin Mike , Xi Yongjie , Lim Thiam Huat
Published: March 2011

"Goes Green & Copper", is the strategy to introduce 1) environmentally friendly materials to meet RoHS (Restriction of the use of Hazardous Substances) & WEEE (Waste Electrical & Electronic Equipment) requirements and 2) Cu wires for superior electrical, mechanical & intermetallics properties compared to Au wires. A complete package level qualification was planned to assess the reliability performaces in discrete packages. This paper will discuss in details on investigation of lateral die crack failure during reliability. Process & materials investigation revealed that interaction of leadframe paddle construction, die attach method, die construction & mold compound factors play important role in aggravating lateral die crack. FEA (finite element analysis) was performed to understand the thermo-mechanical stress distribution within the die & package. Re-qualification was performed & reliability results showed that lateral die crack failure could be eliminated with proper combination of BOM selection.
Study on the Reliability of Nano-Structured Polymer-Metal Composite for Thermal Interface Material
Authors: Zhang Lei , Luo Xin , Lu Xiuzhen , Liu Johan
Published: March 2011

The need for higher performance electronic products is posing an urgent challenge for us to improve thermal management techniques in order to maintain reliability of systems and devices. Nano-TIM, a new type of thermal interface material, was developed to improve the heat dissipation of electronic devices. In this paper, the reliability of Nano-TIM was studied. The samples were subjected to thermal and humidity tests with the condition of 40 °, 93%RH for 56 days. Pull tests were used to investigate the shear strength of the samples with Nano-TIM coalesced between two PCBs with Sn coating. The shear strength did not change very much after the thermal and humidity tests. Scanning Electron Microscopy (SEM) analysis techniques were used to determine the morphology of the shear fracture section after pull tests and observe the structure of the cross section of Nano-TIM coalesced between two PCBs with Sn coating.
FPGA Design with Double-Gate Carbon Nanotube Transistors
Authors: Ben Jamaa M. Haykel , Gaillardon Pierre-Emmanuel , Frégonèse Sebastien , De Marchi Michele , De Micheli Giovanni , Zimmer Thomas , O'Connor Ian , Clermidy Fabien
Published: March 2011

Double-gate carbon nanotube field effect transistors (DG-CNTFETs) are novel devices showing an interesting property that consists of controlling the p- or n-type behavior during the device operation. This opens up the opportunity for novel design paradigms. Based on a compact physical model of these devices, we demonstrate the superiority of field-programmable gate arrays (FPGAs) designed with fine-grain DG-CNTFETs compared to FPGAs designed with traditional circuits and with coarse-grain DG-CNTFETs by 13% to 48% respectively in terms of delay.
Alumina Abrasives for Sapphire Substrate Polishing
Authors: Merricks David
Published: March 2011

The development of Light Emitting Diode (LED) technology over the past thirty years, has led to an exponential increase in device efficiency and light output, such that LEDs are now becoming the light source of choice for virtually all applications. High brightness LEDs (HB LEDs) are driving market growth of around 20% year on year, for applications such as LCD TV backlighting and general illumination, where LED lamps are replacing standard incandescent and fluorescent lighting. Sapphire (alpha aluminum oxide) is used as the substrate of choice for around 90% of LED chips, with 2" and 4" wafer diameters being the most commonly used. Some leading companies are transitioning to 6" wafer production next year, with 8" wafer processing on the horizon. It is important to produce defect-free sapphire surfaces, in order to efficiently grow the III-V semiconductor stack, responsible for generating the desired wavelengths of light and this is done by CMP. Silica slurries are mostly used as the final polish, but these have very low removal rates, with polishing times of up to a few hours. Silica slurries also exhibit instability at elevated temperatures generated during long polishing and temperature control is critical. As the industry moves to larger diameter wafers, it will become more important to realize increased throughput and therefore, a faster polishing slurry would have a big advantage. Ferro has developed alumina-based slurries for sapphire polishing, which give faster removal rates and greater stability, whilst producing the required surface quality.
Smart Systems
Authors: Gessner Thomas , Vogel Martina , Otto Thomas , Schulz Stefan E. , Baumann Reinhard
Published: March 2011

The Fraunhofer-Gesellschaft is one of the leading organizations for applied research in Germany and Europe. Its core purpose is the pursuit of knowledge of practical utility. The Fraunhofer Institute for Electronic Nano Systems ENAS is focusing on smart systems integration by using micro and nano technologies. Smart systems integration addresses the demand for miniaturized, multi-functional, self-organizing systems with an interface for communication. The technologies for smart systems and their integration significantly influence the competitiveness of different branches like aeronautics, automotive engineering, security applications, logistics, as well as medical and process engineering. Fraunhofer ENAS accesses on a broad variety of technologies and methods for smart systems integration.
Electroluminescence of End-Capped Poly[9,9-di-(2'-ethylhexyl)fluorenyl-2,7-diyl] Blended with F8BT
Authors: Zhang Qiushu , Zhang Sihui
Published: March 2011

We report on the fabrication and characterization of light-emitting diodes (LEDs) based on blended end-capped poly[9,9-di-(2'-ethylhexyl)fluorenyl-2,7-diyl] (PF2/6). The light emitting polymer thin film layer was dimethylphenyl (DMP)-end-capped PF2/6 or N,N-bis(4-methylphenyl)-N-phenylamine (TPA)-end-capped PF2/6 doped with the green-emitting alternating copolymer poly(9,9'-dioctylfluorene-alt-benzothiadiazole) (F8BT). Blending end-capped PF2/6 with F8BT enhanced device properties compared to either of the pure components. For the devices based on DMP-end-capped PF2/6 doped with 10% F8BT, the electroluminescence (EL) reached a maximum luminance of 1074 cd/m2, a maximum external quantum efficiency of 0.16%, and a maximum luminance efficiency of 0.514 cd/A. The improvement is assigned to efficient energy transfer from host end-capped PF2/6 to guest F8BT. However, the energy transfer was incomplete since EL emission did not exclusively come from F8BT, which we think originates from the presence of the regions where the concentration of F8BT is relatively depleted.
Hydrogenated Silicon Thin Film and Solar Cell Prepared by Electron Cyclotron Resonance Chemical Vapor Deposition Method
Authors: Lee Chien-Chieh , Chang Jenq-Yang , Chu Yen-Ho , Lien Chung-Min , Chen I-Chen , Li Tomi
Published: March 2011

Hydrogenated silicon thin film was deposited on glass substrate using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) system. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) were used to measure the film properties. It showed that higher deposition rate (>2nm/sec) and lower microstructure parameter (20%<R*<30%) could be achieved with increasing input power and decreasing hydrogen dilution ratio (H2/SiH4). In addition, p-type and n-type hydrogenated amorphous silicon thin films were grown using SiH4/Ar/H2/B2H6 or PH3 gases. Hall mobility decreased with increasing the doping gas flow rate. The carrier concentration exhibited an entirely converse behavior. With increasing the doping gas flow rate, the concentrations increased and the highest values of 5.2×1019 cm-3 (3.9×1019 cm-3) at H2/B2H6 (H2/PH3) of ~20 for p-type (n-type) hydrogenated amorphous Si thin films were achieved. These films are suitable for the amorphous Si thin film solar cell.
Defect Evaluation by Photoluminescence for Uniaxially Strained Si-On-Insulator
Authors: Wang Dong , Yamamoto Keisuke , Gao Hongye , Yang Haigui , Nakashima Hiroshi
Published: March 2011

Uniaxial strain was introduced to Si-on-insulator (SOI) substrate by SiN deposition using electron cyclotron resonance sputtering followed by gate-opening using lift-off technique. Then thermal treatments were performed at different temperatures. Strain-relaxation was observed by Raman spectroscopy. Photolumine-scence (PL) was used to evaluate defects generated during strain-relaxation. Defect-related PL signal was observed for the thermally-treated strained channel. The intensity of defect-related PL signal increased with increasing annealing temperature. The energy position and profile of defect-related PL signal also varied with annealing temperature and SiN thickness.
Light Trapping for High Efficiency Heterojunction Crystalline Si Solar Cells
Authors: Wang Qi , Xu Yueqin , Iwaniczko Eugene , Page Matt
Published: March 2011

Light trapping plays an important role to achieve high short circuit current density (Jsc) and high efficiency for amorphous/crystalline Si heterojunction solar cells. Si heterojunction uses hydrogenated amorphous Si for emitter and back contact. This structure of solar cell posses highest open circuit voltage of 0.747 V at one sun for c-Si based solar cells. It also suggests that over 25% record-high efficiency is possible with further improvement of Jsc. Light trapping has two important tasks. The first one is to reduce the surface reflectance of light to zero for the solar spectrum that Si has a response. The second one is to increase the effective absorption length to capture all the photon. For Si heterojunction solar cell, surface texturing, anti-reflectance indium tin oxides (ITO) layer at the front and back are the key area to improve the light trapping.
Fabrication and Quantum Confinement Investigation of Ge Multiple Quantum Wells with Si3N4 Barriers
Authors: Chen Jian , Lee Sammy , Huang Shujuan
Published: March 2011

Fabrication process and quantum confinement effect of Ge multiple quantum wells (MQWs) structure with Si3N4 barriers were investigated for its potential application in 3rd-Generation tandem solar cells. The structure was fabricated by alternating deposition of Ge and Si3N4 layers using magnetron co-sputtering and crystallized by rapid thermal annealing (RTA). The Ge MQWs structures were characterized by X-ray reflection, Raman microscopy and glancing incidence X-ray diffraction. Optical properties were analyzed by transmission and reflection measurements. Above characterizations demonstrated that Ge has formed polycrystalline layers restrained between amorphous Si3N4 barriers after annealing. The crystallization temperature increased with decreasing Ge layer thickness; in other words, thicker Ge layer is prone to crystallize. And this Ge layer crystallinity is found to be important in deciding quantum confinement effect achieved in the multilayer structure.
Structural and Optical Properties of Porous SiGe/Si Multilayer Films
Authors: Zhou Bi , Li X. M. , Pan Shu W. , Chen Song Y. , Li Cheng
Published: March 2011

The structural and optical properties of heterogeneous SiGe/Si multilayered films, which was prepared through a combination of ultrahigh vacuum chemical vapor deposition (UHVCVD) and electrochemical anodization (ECA), have been investigated. The structural parameters of multilayer films before ECA were determined by double crystal X-ray diffraction and the simulation. The visible luminescence spectra with multiple emission peaks been detected in the temperature range from 10 K to room temperature. The origins of PL with multiple peaks were discussed in detail.
The Influence Of Silicon Orientation On Surface Blistering Behaviors for Molecular Hydrogen Ion Implantation
Authors: Hsiao Yu Cheng , Liang Jenq-Horng , Lin Chih-Ming
Published: March 2011

This study attempted to investigate the silicon orientation effects on surface blistering behavior under the same implantation condition and thermal budget, Si<100>, Si<111>, and Si<110> were employed and implanted with molecular hydrogen ions (H2+) with a kinetic energy level 200 keV and molecular ion fluence of 2.5×1016 cm-2. Following implantation, the variation occurred at specimen's surface under isothermal annealing in an atmosphere ambient were in-situ observed using optical microscopy (OM). Raman scattering spectroscopy (RSS) were adopted to detect radiation damage and secondary ion mass spectroscopy (SIMS) were used to measure the hydrogen trapping depth in the specimens. In our investigation, a post-annealing temperature fell into the regime of Te-Tt for fabricating SOI material with difference silicon orientation is the most optimal under consideration.
Aqueous Electrodeposition and Mechanism of Iron Group-Vanadium Ternary Alloys
Authors: Schwartz M. , Yoo B. Y. , Nobe Ken
Published: March 2011

Composition of ternary CoFeV deposits can be varied and tailored by control of the [Fe]/[Fe + Co] solution molar ratios and solution pH. Near 2V Permendur compositions were obtained with Bs of 2.35T and Bs of 2.39T for DC and PC deposits, respectively. Annealing deposits in vacuum at 820oC for 2 hours increased Br to equivalent 2V Permunder. X-ray diffraction patterns show microstructures of mixed HCP, FCC and BCC planes, depending on deposit composition. Co-rich deposits had HCP preferred orientation but as Fe content increases HCP plane disappeared and Fe BCC plane became the preferred orientation. Surface morphology changed from a needle-like structure in Co-rich deposits to nodular appearance with increasing Fe content. A hydrogen atom mechanism for the reduction of the oxovanadium, Co(II) and Fe(II) within the heterodinuclear and heterotrinuclear biscitrate complexes is proposed. This mechanism is also applicable to aqueous electrodeposition of IG-Mo and IG-W alloys.
Electrodeposition of Ni/Cu Multilayers Nanowires Using Alumina Template
Authors: Cojocaru Paula , Leserri Andrea , Magagnin Luca , Vázquez Manuel , Carac Geta
Published: March 2011

Nickel/copper multilayer nanowires have been electrodeposited in sulphamate electrolytes containing nickel and copper ions by alternating potential pulses using alumina template. In order to compare the wires and bulk behavior, nano-thick Ni/Cu multilayers bulk were electrodeposited on sputtered gold silicon under the same conditions. The optimal deposition potential range for nickel was between -1.2 and -1.25 V vs. a saturated calomel electrode (SCE) to minimize the copper content and to prevent formation of nickel hydroxide and nickel hydride. The optimal deposition potential range for copper was between -0.4 and -0.8 V vs. SCE. Magnetic properties of Ni/Cu multilayers were determined at various Ni and Cu layer spacing.
Investigations on Micromolds for Dispensing Low Viscosity Epoxies for MEMS Applications
Authors: Leng Christoph H. , Ruffert Christine , Rissing Lutz
Published: March 2011

The area of Micro-electromechanical Systems (MEMS) is a rapidly emerging field, offering solutions for manifold applications of miniaturized systems. Nowadays, MEMS are standard components of every automobile, including e.g. an accelerometer used for airbag activation. They are also found in various medical devices and part of everyday consumer electronics such as mobile phones, projectors, CD or DVD players, and others. To further increase the acceptance of MEMS, the development of low-cost, highly productive processes is necessary. This is also important if the aim is to produce rather small quantities. The standard material used by the electronics industry is silicon, which still is complex and quite expensive material to be produced. Otherwise, polymers can be provided in large amounts with a high variety of material characteristics. Polymers can also be applied for the fabrication of MEMS by injection molding, hot embossing or stereolithography. They are especially well suited for microfluidic applications.
Sex-biased suppression of chemically induced neural carcinogenesis in congenic BDIX.BDIV-Mss4a rats
Authors: Koelsch Bernd , Winzen-Reichert Bettina , Fischer Christine , Kutritz Andrea , van den Berg Linda , Kindler-Röhrborn Andrea
Published: March 2011

We previously mapped several gene loci influencing cancer risk of inbred BDIV and BDIX rats, resistant and susceptible, respectively, to N-ethyl- N-nitrosourea (ENU)-induced malignant peripheral nerve sheath tumors (MPNSTs). On the basis of a genomewide association analysis using a (BDIV × BDIX) F2 generation the Mss4 locus on rat chromosome 6 was predicted to mediate resistance to MPNST development in the trigeminal nerves, preferentially in females. F2 females homozygous for D6Mit1 proved almost exclusively resistant to peripheral neurooncogenesis, with no effect detectable in males. To functionally verify Mss4, a congenic BDIX rat strain was generated carrying a corresponding BDIV genomic fragment. On treatment with ENU, congenic BDIX.BDIV- Mss4a rats showed a 2.4-fold lower MPNST rate and a 55-day-longer survival time compared with BDIX animals. The sex-specific effect observed in F2 rats was less pronounced in BDIX.BDIV- Mss4a congenics, with males, too, being protected against MPNST but to a lesser extent than females. Transcription profiling using trigeminal nerve tissue of BDIX, BDIV, and BDIX.BDIV- Mss4a congenics of both sexes revealed 61 genes located in the Mss4a fragment differentially expressed between BDIV and BDIX rats. In congenic rats each gene either displayed trans-regulated BDIX-like expression strength or cis-regulated BDIV-like transcript levels or intermediate expression without marked sex differences. Genomewide a number of genes exhibiting male-biased expression in the BDIX rat strain displayed a reversal of the sexual dimorphism in congenic rats similar to the BDIV expression pattern, which might be the basis of preferential protection of females against MPNST development.
Evaluating the Use of Optical Coherence Tomography in Optic Neuritis
Authors: Costello Fiona
Published: March 2011

Optic neuritis (ON) is an inflammatory optic nerve injury, which is strongly associated with multiple sclerosis (MS). Axonal damage in the optic nerve manifests as retinal nerve fiber layer (RNFL) deficits, which can be readily quantified with optical coherence tomography (OCT). The RNFL represents the most proximal region of the afferent visual pathway; and, as such, is a unique region of the central nervous system (CNS) because it lacks myelin. Changes in retinal integrity can be correlated with reliable and quantifiable visual outcomes to provide a structural-functional paradigm of CNS injury. Because the eye provides a unique “view” into the effects of CNS inflammation, the ON “system model” may provide greater understanding about disease mechanisms, which underpin disability in MS. This review addresses the applications of OCT in study of ON patients, with specific reference to the published reports to date. The future role of OCT is discussed, both in terms of the potential gains and certain challenges associated with this evolving technology.
Change Point Detection with Robust Control Chart
Authors: Kooi Huat Ng , Midi Habshah
Published: March 2011

Monitoring a process over time using a control chart allows quick detection of unusual states. In phase I, some historical process data, assumed to come from an in‐control process, are used to construct the control limits. In Phase II, the process is monitored for an ongoing basis using control limits from Phase I. In Phase II, observations falling outside the control limits or unusual patterns of observations signal that the process has shifted from in‐control process settings. Such signals trigger a search for assignable cause and, if the cause is found, corrective action will be implemented to prevent its recurrence. The purpose of this paper is to introduce a new methodology appropriate for constructing a robust control chart when a nonnormal or a contaminated data that may arise in phase I state. Through extensive Monte Carlo simulations, we examine the behaviors and performances of the proposed MM robust control chart when there is a process shift in mean.
A Note on Stabilization of Discrete Nonlinear Systems
Authors: Tang Fengjun , Yuan Rong
Published: March 2011

We deal with the stabilization problem of discrete
nonlinear systems. We construct a control Lyapunov function on discrete nonlinear systems. Then, we present a new method to construct a continuous state
feedback law.
Micro-RNA Expression and Function in Lymphomas
Authors: Sandhu Sukhinder K. , Croce Carlo M. , Garzon Ramiro
Published: March 2011

The recent discovery of microRNAs (miRNAs) has introduced a new layer of complexity to the process of gene regulation. MiRNAs are essential for cellular function, and their dysregulation often results in disease. Study of miRNA expression and function in animal models and human lymphomas has improved our knowledge of the pathogenesis of this heterogeneous disease. In this paper, we attempt to describe the expression of miRNAs and their function in lymphomas and discuss potential miRNA-based therapies in the diagnosis and treatment of lymphomas.
On Approximate "Equation missing" -Ternary "Equation missing" -Homomorphisms: A Fixed Point Approach
Authors: Gordji MEshaghi , Alizadeh Z , Cho YJ , Khodaei H
Published: March 2011

Using fixed point methods, we prove the stability and superstability of "Equation missing"-ternary additive, quadratic, cubic, and quartic homomorphisms in "Equation missing"-ternary rings for the functional equation "Equation missing", for each "Equation missing".
Optimization of Parameters of Asymptotically Stable Systems
Authors: Guerman Anna , Seabra Ana , Smirnov Georgi
Published: March 2011

This work deals with numerical methods of parameter optimization for asymptotically stable systems. We formulate a special mathematical programming problem that allows us to determine
optimal parameters of a stabilizer. This problem involves solutions to a differential equation. We show how to chose the mesh in order to obtain discrete problem guaranteeing the necessary accuracy. The developed methodology is illustrated by an example concerning optimization of parameters for a satellite stabilization system.
Zingiber zerumbet (L.) Smith: A Review of Its Ethnomedicinal, Chemical, and Pharmacological Uses
Authors: Yob N. J. , Jofrry S. Mohd. , Affandi M. M. R. Meor. Mohd. , Teh L. K. , Salleh M. Z. , Zakaria Z. A.
Published: March 2011

Zingiber zerumbet Sm., locally known to the Malay as “Lempoyang,” is a perennial herb found in many tropical countries, including Malaysia. The rhizomes of Z. zerumbet, particularly, have been regularly used as food flavouring and appetizer in various Malays′ cuisines while the rhizomes extracts have been used in Malay traditional medicine to treat various types of ailments (e.g., inflammatory‐ and pain‐mediated diseases, worm infestation and diarrhea). Research carried out using different in vitro and in vivo assays of biological evaluation support most of these claims. The active pharmacological component of Z. zerumbet rhizomes most widely studied is zerumbone. This paper presents the botany, traditional uses, chemistry, and pharmacology of this medicinal plant.
A Polynomial Preconditioner for the CMRH Algorithm
Authors: Lai Jiangzhou , Lu Linzhang , Xu Shiji
Published: March 2011

Many large and sparse linear systems can be solved efficiently by restarted GMRES and
CMRH methods Sadok 1999. The CMRH(m) method is less expensive and requires slightly less storage
than GMRES(m). But like GMRES, the restarted CMRH method may not converge. In
order to remedy this defect, this paper presents a polynomial preconditioner for CMRH‐based
algorithm. Numerical experiments are given to show that the polynomial preconditioner is
quite simple and easily constructed and the preconditioned CMRH(m) with the polynomial
preconditioner has better performance than CMRH(m).
Epigenetic Effects and Molecular Mechanisms of Tumorigenesis Induced by Cigarette Smoke: An Overview
Authors: Chen Rong-Jane , Chang Louis W. , Lin Pinpin , Wang Ying-Jan
Published: March 2011

Cigarette smoking is one of the major causes of carcinogenesis. Direct genotoxicity induced by cigarette smoke leads to initiation of carcinogenesis. Nongenotoxic (epigenetic) effects of cigarette smoke also act as modulators altering cellular functions. These two effects underlie the mechanisms of tumor promotion and progression. While there is no lack of general reviews on the genotoxic and carcinogenic potentials of cigarette smoke in lung carcinogenesis, updated review on the epigenetic effects and molecular mechanisms of cigarette smoke and carcinogenesis, not limited to lung, is lacking. We are presenting a comprehensive review of recent investigations on cigarette smoke, with special attentions to nicotine, NNK, and PAHs. The current understanding on their molecular mechanisms include (1) receptors, (2) cell cycle regulators, (3) signaling pathways, (4) apoptosis mediators, (5) angiogenic factors, and (6) invasive and metastasis mediators. This review highlighted the complexity biological responses to cigarette smoke components and their involvements in tumorigenesis.
Solution of Fractional Order System of Bagley‐Torvik Equation Using Evolutionary Computational Intelligence
Authors: Raja Muhammad Asif Zahoor , Khan Junaid Ali , Qureshi Ijaz Mansoor
Published: March 2011

A stochastic technique has been developed for the solution of fractional order system represented by Bagley‐Torvik equation. The mathematical model of the equation was developed with the help of feed‐forward artificial neural networks. The training of the networks was made with evolutionary computational intelligence based on genetic algorithm hybrid with pattern search technique. Designed scheme was successfully applied to different forms of the equation. Results are compared with standard approximate analytic, stochastic numerical solvers and exact solutions.
Recent Advancements in Fractal Geometric‐Based Nonlinear Time Series Solutions to the Micro‐Quasistatic Thermoviscoelastic Creep for Rough Surfaces in Contact
Authors: Abuzeid Osama M. , Al-Rabadi Anas N. , Alkhaldi Hashem S.
Published: March 2011

To understand the tripological contact phenomena, both mathematical and experimental models are needed. In this work, fractal mathematical models are used to model the experimental results obtained from literature. Fractal geometry, using a deterministic Cantor structure, is used to model the surface topography, where recent advancements in thermoviscoelastic creep contact of rough surfaces are introduced. Various viscoelastic idealizations are used to model the surface materials, for example, Maxwell, Kelvin‐Voigt, Standard Linear Solid and Jeffrey media. Such media are modelled as arrangements of elastic springs and viscous dashpots in parallel and/or in series. Asymptotic power laws, through hypergeometric series, were used to express the surface creep as a function of remote forces, body temperatures and time. The introduced models are valid only when the creep approach of the contact surfaces is in the order of the size of the surface roughness. The obtained results using such models, which admit closed‐form solutions, are displayed graphically for selected values of the systems′ parameters; the fractal surface roughness and various material properties. Results obtained showed good agreement with published experimental results, where the utilized methodology can be further extended to the utilization for the contact of surfaces within micro‐ and nano‐electronic devices, circuits and systems.
Different Transcriptional Profiles of Human Monocyte-Derived Dendritic Cells Infected with Distinct Strains ofMycobacterium tuberculosisandMycobacterium bovisBacillus Calmette-Guérin
Authors: Sanarico Nunzia , Colone Alessia , Grassi Manuela , Speranza Viviana , Giovannini Daniela , Ciaramella Antonio , Colizzi Vittorio , Mariani Francesca
Published: March 2011

In order to analyze dendritic cells (DCs) activation following infection with different mycobacterial strains, we studied the expression profiles of 165 genes of human monocyte-derived DCs infected with H37Rv, a virulentMycobacterium tuberculosis(MTB) laboratory strain, CMT97, a clinical MTB isolate,Mycobacterium bovisbacillus Calmette-Guérin (BCG), Aventis Pasteur, and BCG Japan, both employed as vaccine against tuberculosis. The analysis of the gene expression reveals that, despite a set of genes similarly modulated, DCs response resulted strain dependent. In particular, H37Rv significantly upregulated EBI3 expression compared with BCG Japan, while it was the only strain that failed to release a significant IL-10 amount. Of note, BCG Japan showed a marked increase in CCR7 and TNF-αexpression regarding both MTB strains and it resulted the only strain failing in exponential intracellular growth. Our results suggest that DCs display the ability to elicit a tailored strain-specific immune response.
Exogenous Control of the Expression of Group I CD1 Molecules Competent for Presentation of Microbial Nonpeptide Antigens to Human T Lymphocytes
Authors: Aquino Angelo , Graziani Grazia , Franzese Ornella , Prete Salvatore P. , Bonmassar Enzo , Bonmassar Laura , D'Atri Stefania
Published: March 2011

Group I CD1 (CD1a, CD1b, and CD1c) glycoproteins expressed on immature and mature dendritic cells present nonpeptide antigens (i.e., lipid or glycolipid molecules mainly of microbial origin) to T cells. Cytotoxic CD1-restricted T lymphocytes recognizing mycobacterial lipid antigens were found in tuberculosis patients. However, thanks to a complex interplay betweenmycobacteriaand CD1 system,M. tuberculosispossesses a successful tactic based, at least in part, on CD1 downregulation to evade CD1-dependent immunity. On the ground of these findings, it is reasonable to hypothesize that modulation of CD1 protein expression by chemical, biological, or infectious agents could influence host's immune reactivity againstM. tuberculosis-associated lipids, possibly affecting antitubercular resistance. This scenario prompted us to perform a detailed analysis of the literature concerning the effect of external agents on Group I CD1 expression in order to obtain valuable information on the possible strategies to be adopted for driving properly CD1-dependent immune functions in human pathology and in particular, in human tuberculosis.
Effect of Policy Reforms on Market Efficiency: Evidence from Dhaka Stock Exchange
Authors: Alam Md. Mahmudul , Yasmin Shakila , Rahman Mahmudur , Uddin Md. Gazi Salah
Published: March 2011

The paper tries to find evidence supporting the impact of continuous policy reforms on the market efficiency on the Dhaka Stock Exchange (DSE). Different policies formed/reformed from 1994 to 2005 were categorized in eleven groups depending on their time of issue and subject matter. To get the result, both nonparametric test (Kolmogrov‐Smirnov normality test and run test) and parametric test (autocorrelation test, autoregression) have been performed. Analyses were done for each policy group, and it is found that formed/reformed policies for DSE during the study period failed to improve the market efficiency even in the weak form level.