bluuebunny/crossref_metadata_2025 huggingface dataset:
c-Myc and Rel/NF-κB Are the Two Master Transcriptional Systems Activated in the Latency III Program of Epstein-Barr Virus-Immortalized B Cells
Authors: Faumont Nathalie , Durand-Panteix Stéphanie , Schlee Martin , Grömminger Sebastian , Schuhmacher Marino , Hölzel Michael , Laux Gerhard , Mailhammer Reinhard , Rosenwald Andreas , Staudt Louis M. , Bornkamm Georg W. , Feuillard Jean
Published: March 2009

The Epstein-Barr virus (EBV) latency III program imposed by EBNA2 and LMP1 is directly responsible for immortalization of B cells in vitro and is thought to mediate most immunodeficiency-related posttransplant lymphoproliferative diseases in vivo. To answer the question whether and how this proliferation program is related to c-Myc, we have established the transcriptome of both c-Myc and EBV latency III proliferation programs using a Lymphochip specialized microarray. In addition to EBV-positive latency I Burkitt lymphoma lines and lymphoblastoid cell lines (LCLs), we used an LCL expressing an estrogen-regulatable EBNA2 fusion protein (EREB2-5) and derivative B-cell lines expressing a constitutively active or tetracycline-regulatable c-
myc
gene. A total of 897 genes were found to be fourfold or more up- or downregulated in either one or both proliferation programs compared to the expression profile of resting EREB2-5 cells. A total of 661 (74%) of these were regulated similarly in both programs. Numerous repressed genes were known targets of STAT1, and most induced genes were known to be upregulated by c-Myc and to be involved in cell proliferation. In keeping with the gene expression patterns, inactivation of c-Myc by a chemical inhibitor or by conditional expression of dominant-negative c-Myc and Max mutants led to proliferation arrest of LCLs. Most genes differently regulated in both proliferation programs corresponded to genes induced by NF-κB in LCLs, and many of them coded for immunoregulatory and/or antiapoptotic molecules. Thus, c-Myc and NF-κB are the two main transcription factors responsible for the phenotype, growth pattern, and biological properties of cells driven into proliferation by EBV.
Stromal Cell-Mediated Suppression of Human T-Cell Leukemia Virus Type 1 Expression In Vitro and In Vivo by Type I Interferon
Authors: Kinpara Shuichi , Hasegawa Atsuhiko , Utsunomiya Atae , Nishitsuji Hironori , Furukawa Hiroyuki , Masuda Takao , Kannagi Mari
Published: March 2009

Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia (ATL), HTLV-1-associated myelopathy/tropical spastic paraparesis, and other inflammatory diseases. Despite such severe outcomes of HTLV-1 infection, the level of HTLV-1 expression in vivo is very low and rapidly increases after transfer of cells to culture conditions. The mechanisms of this phenomenon have remained obscure. In the present study, we found that human and mouse stromal cells, such as epithelial cells and fibroblasts, suppressed HTLV-1 expression in ATL and non-ATL HTLV-1-infected cells. HTLV-1 mRNA and proteins in HTLV-1-infected cells markedly decreased upon coculture with human epithelial-like cells (HEK293T) or mouse embryo fibroblasts (NIH 3T3). When infected cells were reisolated from the cocultures, viral expression was restored to the original level over the following 48 h. Spontaneous induction of HTLV-1 expression in primary ATL cells in the first 24 h of culture was also inhibited by coculture with HEK293T cells. Coculture of HTLV-1-infected cells and HEK293T cells induced type I interferon responses, as detected by beta interferon (IFN-β) promoter activation and IFN-stimulated gene upregulation. HEK293T-mediated suppression of HTLV-1 expression was partly inhibited by antibodies to human IFN-α/β receptor. NIH 3T3-mediated suppression was markedly abrogated by neutralizing antibodies to mouse IFN-β. Furthermore, viral expression in HTLV-1-infected cells was significantly suppressed when the infected cells were intraperitoneally injected into wild-type mice but not IFN regulatory factor 7 knockout mice that are deficient of type I IFN responses. These findings indicate that the innate immune system suppresses HTLV-1 expression in vivo, at least through type I IFN.
Enhanced Exposure of the CD4-Binding Site to Neutralizing Antibodies by Structural Design of a Membrane-Anchored Human Immunodeficiency Virus Type 1 gp120 Domain
Authors: Wu Lan , Zhou Tongqing , Yang Zhi-yong , Svehla Krisha , O'Dell Sijy , Louder Mark K. , Xu Ling , Mascola John R. , Burton Dennis R. , Hoxie James A. , Doms Robert W. , Kwong Peter D. , Nabel Gary J.
Published: March 2009

The broadly neutralizing antibody immunoglobulin G1 (IgG1) b12 binds to a conformationally conserved surface on the outer domain of the human immunodeficiency virus type 1 (HIV-1) gp120 envelope (Env) glycoprotein. To develop outer domain proteins (ODs) that could be recognized selectively by CD4-binding-site (CD4-BS) antibodies, membrane-anchored ODs were generated from an HIV-1 clade B virus, TA1 R3A, which was highly sensitive to neutralization by the IgG1 b12 antibody. A 231-residue fragment of gp120 (residues 252 to 482) linked to transmembrane regions from CD4 showed b12 binding comparable to that of the native Env spike as measured by flow cytometry. Truncation of the β20-β21 hairpin (residues 422 to 436 to Gly-Gly) improved overall protein expression. Replacement of the immunodominant central 20 amino acids of the V3 loop (residues 302 to 323) with a basic hexapeptide (NTRGRR) increased b12 reactivity further. Surface calculations indicated that the ratio of b12 epitope to exposed immunogenic surface in the optimized OD increased to over 30%. This OD variant [OD(GSL)(Δβ20-21)(hCD4-TM)] was recognized by b12 and another CD4-BS-reactive antibody, b13, but not by eight other CD4-BS antibodies with limited neutralization potency. Furthermore, optimized membrane-anchored OD selectively absorbed neutralizing activity from complex antisera and b12. Structurally designed membrane-anchored ODs represent candidate immunogens to elicit or to allow the detection of broadly neutralizing antibodies to the conserved site of CD4 binding on HIV-1 gp120.
Voltammetric behavior of 4-acetamidohippuric acid and 4-acetamidobenzoic acid on a disposable carbon electrode and their determination in human urine
Authors: Wang Lai-Hao , Zeng Shih-Ying
Published: March 2009

The voltammetric behavior of 4-aminobenzoic acid (PABA) and its acetylated metabolite on glassy carbon, carbon fiber or carbon paste electrodes was investigated in an aqueous supporting electrolyte. 4-Aminohippuric acid (4-AHA), 4-acetamidobenzoic acid (4-AMB) and 4-acetamidohippuric acid (4-Ac-AHA) can be separated on a capillary carbon paste electrode in 0.1 M lithium perchlorate. The oxidation potentials of PABA, 4-AHA, 4-AMB and 4-Ac-AHA were 0.70, 0.88, 1.06 and 1.10 V on capillary CPE, respectively. The electrooxidation process is used for simultaneous quantitative determination of acetylated metabolites in urine.
Intramolecular alkoxide-tethered permethyltitanocene(III) complexes – synthesis and crystal structure
Authors: Varga Vojtech , Císařová Ivana , Horáček Michal , Pinkas Jiří , Kubišta Jiří , Mach Karel
Published: March 2009

Singly tucked-in titanocene [Ti(III)(η5-C5Me5)(η5:η1-C5Me4CH2)] (1) reacted readily with di-tert-butyl ketone and 2,4,6-trimethylacetophenone to give permethyltitanocene derivatives [Ti(III)(η5-C5Me5){η5-C5Me4CH2C(t-Bu)2O-κO}] (2) and [(Ti(III)(η5-C5Me5)-{η5-C5Me4CH2CMe(C6H2Me3)O-κO}] (3) with the tetramethylcyclopentadienyl ring tethered to the titanium atom by ethoxy group disubstituted at Cα. Crystal structures of 2 and 3 showed that the Ti–O bond is only slightly inclined to the tethered cyclopentadienyl ligand, and the bulky mesityl or tert-butyl substituents did not impose an observable steric hindrance into molecules of 2 and 3. Whereas the Ti–O bond lengths in 2 and 3 do not significantly differ, a higher wavenumber of the 1a1 → b2 electronic transition for 2 (7326 cm–1) compared with that for 3 (6666 cm–1) indicates a more efficient oxygen-to-titanium π-electron back donation in 2. This is induced by two electron-donating tert-butyl groups on Cα compared with a combined effect of electron-donating methyl and electron-attracting mesityl substituents in 3.
SOFTWARE REUSABILITY MODEL FOR PROCEDURE BASED DOMAIN-SPECIFIC SOFTWARE COMPONENTS
Authors: SANDHU PARVINDER SINGH , SINGH HARDEEP
Published: March 2009

Automatic reusability appraisal is helpful in evaluating the quality of developed or developing reusable software components and in identification of reusable components from existing legacy systems; that can save cost of developing the software from scratch. But the issue of how to identify reusable components from existing systems has remained relatively unexplored. In this paper, we mention a two-tier approach by studying the structural attributes as well as usability or relevancy of the component to a particular domain. We evaluate Probabilistic Latent Semantic Analysis (PLSA) approach, LSA's Singular Value Decomposition (SVD) technique, LSA's Semi-Discrete Matrix Decomposition (SDD) technique and Naïve Bayes approach to determine the Domain Relevancy of software components. It exploits the fact that Feature Vector codes can be seen as documents containing terms — the identifiers present in the components — and so text modeling methods that capture co-occurrence information in low-dimensional spaces can be used. In this research work, structural attributes of software components are explored using software metrics and quality of the software is inferred by Neuro-Fuzzy (NF) Inference engine, taking the metric values as input. The influence of different factors on the reusability is studied and the condition for the optimum reusability index is derived using Taguchi Analysis. The NF system is optimized by selecting initial rule-base through modified ID3 decision tree algorithm in combination with the results of Taguchi Analysis. The calculated reusability value enables to identify a good quality code automatically. It is found that the reusability value determined is close to the manual analysis used to be performed by the programmers or repository managers. So, the system developed can be used to enhance the productivity and quality of software development.
A HIGH-EFFICIENCY KNOWLEDGE MANAGEMENT SYSTEM BASED ON HABITUAL DOMAINS AND INTELLIGENT AGENTS
Authors: CHANG YI-HSING , YANG CHING-LUNG
Published: March 2009

In this paper, a high-efficiency knowledge management system, HDIA_KMS, based on habitual domains and intelligent agents is proposed. The design concept of the system is to use an agent community to deal with the activities of knowledge management effectively, that is, knowledge sharing, knowledge classification, knowledge creation, and knowledge recovery. The features of this system are: collecting the surfing habits of each user and finding hidden patterns of departments to recommend articles by data mining; classifying the knowledge articles in accordance with departments and therefore rapidly finding out suitable documents for users; providing personal service through personal profiles; creating new knowledge documents by discussing among users; accepting and reclassifying improperly classified articles found by users; taking the abilities of collaboration, independence and automation of agents to help users use and improve the effects of HDIA_KMS. The PASSI methodology is adopted to analyze and design the system, and agents protocols follow the FIPA specifications.
A LINEAR SPACE DATA STRUCTURE FOR ORTHOGONAL RANGE REPORTING AND EMPTINESS QUERIES
Authors: NEKRICH YAKOV
Published: March 2009

In this paper we present a linear space dynamic data structure for two-dimensional orthogonal range reporting and emptiness queries. This data structure answers range reporting queries in time [Formula: see text] for any ε > 0 and k the size of the answer. Our data structure also supports emptiness and one-reporting queries in time O( log n log log n). The model of computation used in this paper is a unit-cost RAM model.
New aspects of porphyrins and related compounds: self-assembled structures in two-dimensional molecular arrays
Authors: Ariga Katsuhiko , Hill Jonathan P. , Wakayama Yutaka , Akada Misaho , Barrena Esther , de Oteyza Dimas G.
Published: March 2009

The advanced state of development of molecular design and synthetic chemistry of porphyrins and related molecules makes these compounds good candidates for technological appli cations, in which well characterized and designed structures and properties are required. In particular, 2-dimensional molecular level control of porphyrin array structures should reveal new aspects of nanotechnology. In this review, recent research on porphyrin assemblies, including 2-dimensional porphyrin arrays, is described with emphasis on phenol- and quinone-substituted tetrapyrrole units. A series of research aimed at developing strategies for preparation of porphyrin molecular arrays, where several novel aspects of molecular arrays, including phase transitions, ordered 2-D phase boundaries, and hydrogen-bonding networks, are introduced.
Ground- and excited-state interactions of 2,7,12,17-tetraphenylporphycene with model target biomolecules for type-I photodynamic therapy
Authors: Rubio Noemí , Martínez-Junza Víctor , Estruga Jordi , Borrell José I. , Mora Margarita , Sagristá M. Lluïsa , Nonell Santi
Published: March 2009

Biosubstrate-sensitizer binding is one of the factors that enhances the type-I mechanism over the type-II in the whole photodynamic process. 2,7,12,17-Tetraphenylporphycene (TPPo), a second-generation photosensitizer, is a hydrophobic compound with good photophysical properties for photodynamic therapy applications that has proved its ability for the photoinactivation of different cell lines. Nevertheless, little is known about its mechanism of action. This paper focuses on the study of the interaction/binding of TPPo with different model biomolecules that may favor the type-I mechanism in the overall photodynamic process, including nucleosides, proteins, and phospholipids. Compared with more hydrophilic photosensitizers, it is concluded that TPPo is more likely to undergo type-II (singlet oxygen) than type-I (electron transfer) photodynamic processes in biological environments.
A first ABAC phthalocyanine
Authors: Dumoulin Fabienne , Zorlu Yunus , Menaf Ayhan M. , Hirel Catherine , Isci Ümit , Ahsen Vefa
Published: March 2009

The derouting of the selective synthesis of crosswise phthalocyanines (Pcs) applied to a statistical precursors mixture leads to the first member of a new family of Pcs bearing three different substituents: the ABAC phthalocyanines. By playing on the precursors' relative ratio, the yields and selectivity of the method have been optimized.
Interaction of nitric oxide with Ru(II) complexes of deuteroporphyrindimethylester derivatives
Authors: Martin Rudy , Cao Roberto , Esteva Ana M. , Montforts Franz-Peter
Published: March 2009

A new ruthenium(II) porphyrin disulphide derivative, [ Ru ( Pds )( CO )], was obtained from ruthenium(II)(carbonyl)deuteroporphyrin(IX), [ Ru ( DPdc )( CO )] and cystamine. The interaction of this complex with nitric oxide was studied spectrophotometrically and a bathochromic shift of the charge transfer band and considerable change in the α and β bands of the complex were observed. According to the IR spectrum, the product of this interaction is [ Ru ( DmDP )( NO +)( NO 2-)]. [ Ru ( Pds )( CO )] was then self-assembled on polycrystalline gold and characterized by X-ray photoelectron spectroscopy. [ Ru ( Pds )( CO )] was also self-assembled on gold electrode beads and its interaction with nitric oxide in aqueous solution was studied by cyclic voltammetry. A shift in the ruthenium redox process and a new irreversible cathodic peak at -0.59 V were observed, both indicating coordination of NO .
Synthesis of all-cis and all-trans tetrakis(phenylvinylene)-phthalocyanines
Authors: Efimov Alexander , Sariola Essi , Lemmetyinen Helge
Published: March 2009

We have synthesized a series of tetrakis(arylvinylene)phthalocyanines from the corresponding phthalonitriles. Substitution of the para-fluorine in the pentafluorphenyl ring with an alkoxy group from the solvent occurs during the synthesis. This substitution can be suppressed by the addition of zinc chloride or tin chloride to the reaction mixture. According to 1 H and 19 F NMR data, the cis- or trans-conformations of the starting materials are retained during condensation; thus the phthalocyanines formed are in all-cis or all-trans form. Cis-trans photoisomerization occurs easily for phthalonitriles, while phthalocyanines retain their conformations under UV beam.
Introduction to the Special Issue on AAC
Authors: McCoy Kathleen F. , Waller Annalu
Published: March 2009

This article presents an introduction to the special issue on Augmentative and Alternative Communication (AAC).
Electrical Characterization of Mos Memory Devices with Self-Assembled Tungsten Nano-Dots Dispersed in Silicon Nitride
Authors: Pei Yanli , Yin Chengkuan , Nishijima Masahiko , Kojima Toshiya , Noriha Hiroshi , Fukushima Takafumi , Tanaka Tetsu , Koyanagi Mitsumasa
Published: March 2009

Crystallized W-NDs dispersed in silicon nitride were prepared by self-assembled nanodot deposition (SAND) with extremely high density (1.3x1013/cm2) and small size (1~1.5nm), successfully. XPS results show that the high metallic states of tungsten are remained after 800° anneal due to the surround silicon nitride. MOS memory capacitor with W-NDs floating gate and HfO2 blocking dielectric was fabricated. A hysteresis memory window of ~ 1.0V is observed under low sweeping gate voltage of {plus minus}5V. A maximum memory window as large as 29V was obtained with sweeping gate voltage of {plus minus}23V, suggesting that it is a good candidate for multi-bit nonvolatile memory application.
Evaluation of Lateral Ni Diffusion in Si Nanowire Schottky Contact
Authors: Kamimura Hideyuki , Arai Hideaki , Sato Soushi , Kakushima Kuniyuki , Ahmet Parhat , Tsutsui Kazuo , Sugii Nobuyuki , Hattori Takeo , Iwai Hiroshi
Published: March 2009

Lateral Ni diffusion in Si Nanowire to form NiSi schottky contact was characterized by scanning electron microscope at temperatures range from 400 to 700°. Higher temperature annealing results in longer NiSi formation and the length of NiSi increases with the annealing time. The activation energy for NiSi formation on SiNWs are found to be 0.9 eV which is lower than bulk case. One-dimensional diffusion of Ni with SiNW might be the reason for lowering the activation energy.
Silicon Nanocrystals Synthesized by Electron-beam Co-evaporation Method and Their Application for Nonvolatile Memory
Authors: Chen Chen , Jia Rui , Liu Ming , Li Wei Long , Zhu Chen X. , Li Hao F. , Zhang Pei W. , Xie Chang Q. , Wang Qin , Ye Tian C.
Published: March 2009

The Silicon nanocrystals designed for nonvolatile memory applications are firstly prepared by electron beam co-evaporation of Si and SiO2 hybrid. Transmission electron microscopy observation and Raman scattering certify the formation of Si NCs. Metal-oxide-semiconductor capacitor structure with Si NCs embedded in the gate oxide is fabricated to characterize the memory behaviors. High-frequency capacitance-voltage and capacitance-time measurements demonstrate the memory effect of the structure resulting from the charging/discharging behaviors of Si NCs. It is found that flat-band voltage can be changed by adjusting the concentration of Si and SiO2 in hybrids. The Si nanocrystals memory device has yielded good retention characteristics with small charge loss.
Advanced Metrology for Nanoelectronics at the National Institute of Standards and Technology
Authors: Martinez de Pinillos Joaquin V. , Obeng Yaw , Knight Stephen
Published: March 2009

A broad range of programs at the National Institute of Standards and Technology address critical metrology and characterization challenges facing the nanoelectronics industry. A brief history of the program will be included. From these programs we will describe some exemplary projects developing new measurement and characterization techniques for nanodevices. These will include, among others, the use of helium ion microscope, spin-transfer microwave nano-oscillators, characterization of graphene, advanced atomic force microscope, and development of a microcalorimeter-based high resolution X-ray analyzer.
A Systematic Methodology For Low Yield Excursion Analysis
Authors: Xu Xiaoqing , Lin Chi Liang , Tey Thomas , Hsu Michael C.C.
Published: March 2009

Due to the complicated process and huge cost of a modern semiconductor wafer foundry, maintaining stable yield is very critical. If the yield killer is not identified, no containment actions can be taken; if there are no containment actions, the impact will continue and the yield loss will enlarge. In this paper, we have proposed a new systematic methodology for low yield excursion analysis. It integrated Kepner-Tregoe (KT) method and fishbone factor analysis to identify the real yield killer in an efficient and effective manner. From the real case application, it was proven that KT method and fishbone factor analysis can be integrated and resolved the issue successfully. This methodology has great potential to extend to other complicated and urgent daily management issues in a semiconductor fabrication plant.
Drain Bias Effect on the Interface Traps of pMOSFETs under Negative Bias Temperature Stress
Authors: Pan Junyan , Yang Jiaqi , Qiao Ying , Liu X.Y. , Han Ruqi , Kang Jinfeng , Liao C. C. , Wu Hanming , Wu Yongqin
Published: March 2009

Negative bias temperature instability (NBTI) has been a major reliability issue for advanced CMOS technology. Significant drain-bias effect on NBTI has been demonstrated. In this paper, the correlation between drain-bias dependent NBTI and the interface trap (Nit) is studied. Charging pumping measurement was performed to monitor the Nit behavior and on-the-fly technique was used to measure the degradation and recovery behaviors of threshold voltage (ΔVth) in the pMOSFETs. The results show that significant NBTI degradation under higher drain bias can be owed to the drain bias enhanced generation of the non-recovered interfacial traps associated with Si-H bond breaking effect
Challenges of Contacting Lead-Free Packages
Authors: Gschwendtberger Gerhard
Published: March 2009

Lead-free packages require dedicated contact spring coatings. In many cases these coatings can cause significant premature wear issues on the IC test socket which cause dramatic cost of test increases. Other coating solutions suffer from material transfer, which causes unrepeatable contact resistance readings and frequent test socket cleaning cycles. Again, the effect is a significant cost increase by test cell downtime and short socket lifespan. Test socket related cost of test numbers are significantly influenced by above described effects. Dependencies between test socket cleaning cycles, yield loss, test socket spare part consumption and cost of test numbers can be positively influenced by an optimized set-up of important parameters i.e. contact force, coating material, contact scrub, surface quality, contact geometry.
Semiconductor Cleaning Technology -Past and Future
Authors: Ruzyllo Jerzy
Published: March 2009

This paper first briefly reviews selected aspects of the evolution semiconductor cleaning technology underwent over the years then considers challenges it is facing as the new material systems and innovative complex device configurations are being explored by semiconductor industry. Emerging trends are identified and methods developed to assure adequate performance of wafer cleans are outlined. The technique using mixture of anhydrous HF (AHF) and alcoholic solvent is considered as an example of a process which can offer solution to various future challenges.
Process Window Analysis for KrF Photoresists Under Sub-0.11um Groundrules
Authors: Wang Lei , Ji Liang , Wu Peng , Kan Huan , He Weimin , Zhu Zhiguo , Chen Fucheng , Wei Fang , Zhu Jun
Published: March 2009

Amid continuing reduction in average wafer sale price, in the past 30 years, the industry witnesses continuous shrink in production design rules in order to gain performance per unit area on each silicon wafer. While the mainstream wafer production is at 65 and 45 nm with 300 mm diameter wafers, to maintain cost competitiveness, 200 mm wafer companies also start to explore production feasibility under groundrules smaller than 110 nm while maintain the cost advantages in KrF exposure tools systems. The k1 factor under 110 nm with 248 nm illumination will be below 0.35. For example, at 90 nm, at 0.80 NA, the k1 factor is 0.29, which owns the same level of complexity in optical proximity correction compared to 65 nm at 0.93 NA with 193 nm exposure tools. However, due to that the KrF photoresists are originally designed for ground rules greater than 110 nm, such as, 130 nm structures, it is relatively unknown how feasible it is to extend their performance below 110 nm. In this paper, we will show our initial study in CD process window and CD through pitch performance at 90 nm groundrule for 3 critical layers - Active, Gate poly and Contact. The wafer data in process window and optical proximity will be analyzed and compared with performance specifications of the current exposure tools.
EUV Source System Development for 22nm Generation and Beyond
Authors: Lin Benjamin , Brandt David , Farrar Nigel
Published: March 2009

Extreme ultra-violet (EUV) lithography is considered to be the most viable candidate to replace DUV to fulfill Moore's Law for 22nm generation and beyond. In this manuscript, we will show that LPP is the preferred choice for high volume manufacturing due to its scaling capability, enabled by high efficiency in both EUV light production and collection. The LPP EUV source development history and current status are described in this work, including EUV power progress, highly reliable Tin droplet generator, advanced debris mitigation technology and other technology advantages. Future EUV source roadmap provides a detailed schedule and technology requirements for high volume manufacturing EUV sources for the 22nm generation and beyond.
A Cost Effective Spin on Sidewall Material Alternative to the CVD Sidewall Process
Authors: Ho Bang-Ching , Maruyama Daisuke , Sakamoto Rikimaru , Sakaida Yasushi
Published: March 2009

193nm immersion and Hyper NA lithography are used at 45nm and beyond. The next generation of lithography will use a new technology such as Double Pattering, EUV or EB. Double patterning is one of the currently acceptable technologies. Three common double pattern techniques are Litho-Etch-Litho-Etch (LELE), freezing, and sidewall (spacer) process. From a technical standpoint LELE is a very promising process, except for the second litho alignment. However, the cost of ownership will be very high because LELE will cost about twice as much as the current single litho patterning process. In order to build up a suitable double patterning technique, many device makers are developing unique processes. Two of these processes are freezing and sidewall. Flash memory makers are diligently investigating the sidewall process by CVD. This is because of the lack of a second litho alignment step, even with its high cost. The high cost of the CVD process can be reduced if a spin on material is used. One of the goals of this paper is to reduce the cost of ownership by using spin on coatings for the sidewall process. Currently we are investigating this approach to control the sidewall width, profile and other properties.
Investigation on Chemical Mechanical Polishing of GeSbTe for High Density Phase Change Memory
Authors: Zhong Min , Song Zhi-Tang , Liu Bo , Feng Song-lin , Xie Zhi-Feng , Zhang Fu-Xiong , Xiang Yang-Hui
Published: March 2009

Phase change memory (PCM) is considered to be a prospective candidate to replace flash for next generation non-volatile memory. In this paper, we studied GST chemical mechanical polishing (CMP) process characterization and optimization on 8-inch wafers. CMP experiment was performed on GST blanket and pattern wafers. GST CMP process optimization experiment was made in both chemical (slurry) and mechanical (pressure) aspects. AFM data shows that the RMS of roughness has been reduced from 2.151 nm to 1.276 nm after GST CMP on the blanket wafer. On the other hand, high density (40%) GST pattern wafer was polished to evaluate the CMP capability. SEM and EDS results demonstrate that GST via array has been achieved by GST CMP process while the element stoichiometric proportion in GST via is not changed. This work paved the way for PCM development to the commercial high density PCM devices in the future.
Effect of Polisher Kinematics in Reducing Average and Variance of Shear Force and Increasing Removal Rate in Copper CMP
Authors: Sampurno Yasa , Philipossian Ara , Theng Sian , Nemoto Takenao , Gu Xun , Zhuang Yun , Teramoto Akinobu , Ohmi Tadahiro
Published: March 2009

The effect of polisher kinematics on average and variance of shear force and removal rate in copper CMP is investigated. A 'delamination triangle' consisting of average shear force, variance of shear force, and required polishing time is defined, and 'delta' is calculated based on the product of the above three components. In general, low values of 'delta' are preferred to minimize defects during polishing. In the first part of this study, 200-mm blanket copper wafers are polished at constant platen rotation of 25 RPM and polishing pressure of 1.5 PSI with different wafer rotational rates and slurry flow rates. In the second part of this study, polishing is performed at the optimal slurry flow rate of 200 ml/min and wafer rotational rate of 148 RPM with different polishing pressures and platen rotational rates. Results indicate that 'delta' is reduced significantly at higher ratio of wafer to platen rotational rates.
Development of Copper CMP Slurry
Authors: Jing Jianfe , Yang Chunxiao , Cai Xinyuan , Shiao Danny , Wang Shumin
Published: March 2009

Chemical mechanical planarization (CMP) is a critical technology for the copper damascene process. With the development of more advanced technology nodes, New challenges have emerged for the conventional CMP processes--the need for using lower down force while maintaining removal rate to avoid low-k/ultra-low k dielectric film damage and wide over polishing window. Also, surface defects especially corrosion related defects become more stringent as copper line becomes narrower and narrower. In this paper, we share our current efforts and associated results to develop the novel copper slurry for such CMP process. The slurries with different organic additives were evaluated for removal rate, dishing rate, electrochemical analysis and anti-corrosion capability. Based on these results, a novel copper slurry has been developed and it shows the excellent CMP performance.
A Novel Slurry for DRAM Polysilicon CMP
Authors: Wang Chen , Cao Yibin , Yang Chunxiao , Zhou Haifeng , Jing Jianfe , Xia Zhiping , Tang Jingji , Lin Jun , Chiu Charles , Wang Shumin , Yu Chris
Published: March 2009

High removal rate of polysilicon and high selectivity between silicon and oxide, are two important performance targets in DRAM chemical mechanical polishing (CMP). Traditionally, the polysilicon CMP is dominated by mechanical effects, owing to the relatively inert chemical property of silicon. We have shown that chemistry also played an important role in polysilicon polishing. In this paper, a novel polysilicon CMP slurry with an optimized chemistry is reported. It is specifically formulated for DRAM polysilicon polishing. It exhibits high removal rate, high selectivity (silicon/oxide), low defects and excellent surface quality.
Slurry Development Challenges and Solutions for Advanced Node Copper CMP
Authors: Mahulikar Deepak
Published: March 2009

The R&D of Cu CMP started in the late 1980s but was fully implemented in the HVM in the late 1990s and early 2000. Cu CMP was fully implemented for the 130 nm nodes primarily in the Logic devices. In the decade following the Cu CMP introduction, it has grown and changed in significant ways. As of now Cu CMP is a main stay for most BEOL integration schemes and being applied to Memory, 3D and MEMS devices. The success of Cu CMP was due to many enabling events such as Ta barrier development, AMAT Mirra tool design and low selectivity barrier process. As we move from 130 nm nodes into more advanced nodes additional challenges have unfolded. Performance requirements have become quite stringent while CoO reduction pressures are mounting. While the 130 nm process required polishing of Cu, Ta and TEOS at high DF , moderate topography and moderate defects, for 32 nm and beyond polishing of multiple complex materials (like LK, ULK, ALD barriers, MHM, ARC and Copper) at very low DF with very low topography and defects is essential. These challenging needs for the advanced nodes require novel slurry development solutions. Both the Copper and Barrier layer slurries have changed over the decade. Abrasives have changed from Alumina and fumed silica to colloidal silica and coated particles. Significant change in chemistry design is required to address low DF polishing.
Synthesis of Spherical-like Ceria Particle with PVP as Assistant Agent and Its CMP Performance on Shallow Trench Isolation
Authors: Zhang Zefang , Liu Weili , Song Zhi-Tang , Hu Xiaokai
Published: March 2009

Chemical Mechanical Polishing (CMP) has become a widely accepted global panarization technology. Abrasive is one of the key elements during CMP process. Du to its high selectivity, ceria particle is often used as abrasive in shallow trench isolation (STI) CMP slurries. But its irregular shape and agglomeration is not acceptable. In the present work, the spherical-like ceria nano-particles were successfully synthesized by homogeneous precipitation of ammonium cerium nitrate and urea, with Polyvinylpyrrolidone (PVP) as assistant agent. The precipitated ceria particles were characterized by means of XRD, FTIR, SEM and EDS as well as Zeta potential test. The results indicated that these nano-particles had a good dispersibility in water media without addition of any extra dispersing agent. Then, the CMP performance of these nano-particles on STI was investigated. The results indicated that they exhibited high removal selectivity (10.8:1) between silicon dioxide and silicon nitride without any additives.
Thin Oxidation Study with Various Thermodynamic Parameters
Authors: Zhang Ping Linda , Zhang Xu Feng , Wen Ting Dun , Xu Li Feng , Shi Long Xing , Webber Steve E , Willson C Grant , Dean Kim
Published: March 2009

The structure analysis of extremely thin thermally grown SiO2 (< 25 Aå) indicates that most silicon atoms share two of the four tetrahedrally-coordinated oxygen atoms with the adjacent silicon atoms. Molecular mechanics simulation of the single chain of SiO2 tetrahedrons is presented. The extremely thin oxide film is composed of the close-packed short chains of the tetrahedrons perpendicular to Si substrate. Diffusion experiment of an acid vapor through non-oxide polyhydroxystyrene films de-convolutes four prototropic states of fluoresceinamine monolayer to resemble the change of the intermediate states of Si atoms during the thermal oxygen diffusion processes at Si/SiO2 interface.
Understanding and Importance of Defects in Advanced Materials
Authors: Pantisano Luigi , Trojman L , Aoulaiche M , O'Connor R , Kaczer B , Groeseneken G
Published: March 2009

Aggressive CMOS scaling and device performance enhancement is pursued thgrough the use of advanced dielectric and substrate materials. High-k dielectric materials are the key to both dramatically reduce the standby leakage current (and thus power consumption) and to enable the use of high mobility substrates. Critical for device performance and reliability are both the interface quality and bulk defect control. The most important question for high-k materials is always: "How many defects can we allow in these materials and how these are going to influence the performance observed and the reliability?" This paper addresses these issues by looking at both the current understanding of defects in advanced materials for performance and reliability.
Via Resistance Variation Improvement Through Amine Versus Fluorine Based Chemical and O2 Dry Flushing for BiCMOS Technology
Authors: Tee Pei Fang , Teo H. L. , Liew Sung Feng , Chong Shui Fook , Lee Dae Gun , Lee Shannon F.
Published: March 2009

The paper discussed the via resistance variation using different cleaning chemicals known as the amine and fluorine based chemical for 0.6um BiCMOS technology. Single and chain via resistance showed severe drift with fluorine based clean recipe especially at the wafer edge where the failure rate is approximately 28% for chain via resistance and 12% for single via resistance. The baseline chemical, amine based showed low failure rate of less than 3%. Resistance drift is mainly due to the high Ti/TiN polymer residues which are remained at the bottom of the via holes. This is because 0.6um technology tend to generate more by-products since the etch amount is higher compared to other advanced technology which have smaller critical dimension (CD) size. Focus of the paper is mainly on the recipe optimization with fluorine based chemical where the objective is to have comparable via resistance performance with the amine based chemical. Recipe was optimized for different wet cleaning tool, which includes Batch Spray Type and Single Wafer Type. All optimise recipes showed comparable via resistance performance with the amine based chemical. Apart from that, a study on via resistance by adding O2 flushing etch step was conducted. The study was conducted on dual plasma source chamber and single plasma source chamber for BiCMOS technology. Adding O2 flushing step helps to scavenge some of the polymer on the wafer. Single plasma source chamber with O2 flushing step has better performance on production recipe compared to dual plasma source chamber.
Material Technologies for 3D Semiconductor Packaging
Authors: Takano Nozomu , Tanaka Toshiaki , Katogi Shigeki , Nagai Akira
Published: March 2009

The demand of three dimensional PKG (3D PKG) effective for decreasing the mounting area with higher performance is rapidly increasing around mobile electronic devices. The form of the PKG is evolving variously depending on the usage. In this paper, we introduce the materials, material design technologies and the combination of them such as Die Bonding Film for Stacked Multi-Chip PKG, Epoxy Mold Compound and Substrate for Package on Package (PoP) and Underfill Material for Advanced Flip-Chip Package.
Advanced Technologies for In-Line and Post-Processed TSV Integration
Authors: Beyne Eric O. , Swinnen Bart , Van Olmen Jan , Tezcan Deniz S.
Published: March 2009

Through Silicon Vias (TSVs) are an enabler for 3D system integration. A wide diversity of technologies is being proposed. Different application domains have different TSV requirements and justify different integration approaches. Key technologies are discussed for the in-line or post process realization of TSV connections. The impact of wafer thinning and 3D processing on 130nm CMOS devices is discussed.
Electroless Nickel/Gold Under-Bump-Metallization Cost Comparisons
Authors: Strandjord Andrew J. , Scheffler Axel , Zakel Elke , Oppert Thomas , Teutsch Thorsten
Published: March 2009

The Under-Bump-Metallurgy (UBM) is an integral part of all wafer bumping processes. This thin film layer is typically deposited by physical vapor deposition (PVD-sputtering), electroplating, or electroless plating. The electroless plating process is widely considered the lowest cost technology within the electronics packaging industry. Its implementation has been driven by the need to further reduce the costs of manufacturing. In this study, the electroless processes and their costs are analyzed using a new cost model. This cost model is based on a cost-resource structure; where the cost of materials, labor, equipment, facilities, utilities and miscellaneous costs are combined with the product mix and production schedule to calculate costs for each process step.
Next Generation Nickel-Based Bond Pads Enable Copper Wire Bonding
Authors: Chylak Bob , Ling Jamin , Clauberg Horst , Thieme Tom
Published: March 2009

Copper wire bonding has huge cost advantages over gold wire bonding. As a result, low pin count, heavy wire applications have already been converted to copper wire and many companies are in high volume production. Recently, with the price of gold skyrocketing, conversion of high pin count (>250 I/O), high performance applications to Cu has dramatically accelerated. These high performance devices are increasingly relying on low-k materials under the bond pads. Unfortunately, the 33% greater hardness of Cu compared to gold places even greater stress on these inherently fragile materials. This can result in difficulties with pad damage and cratering of the underlying structures. Advancements have been made to copper wire bonders, tools, and wire that have resolved many of these issues and made fine pitch copper wire bonding feasible. Ni-based bond pads have emerged to solve the pad damage problem. Nickel is about 50% harder than copper and four times harder than aluminum so that it provides greater protection against the higher stress resulting from Cu ball bonding, as well as damage during probe. This is especially beneficial for devices with low-k active circuitry under the bond pad. NiPd, NiPdAu, and/or NiAu have demonstrated their great robustness to receive the Cu wire bonding with a huge wire bonding window without any splash and with excellent reliability.
Exploratory NEMS-CMOS Hybrid Devices for Post CMOS Era
Authors: Lee Byoung Hun
Published: March 2009

Si device technology is facing the limit of physical scaling for several reasons such as a power management, an increasing cost of physical scaling, and a variability of nano scale devices. Furthermore, the physical scaling alone does not provide strong benefits on performance as in the past technology generations due to increasing parasitic components (capacitance and resistance) and rising chip temperature. Yet, the demands for increased functionality still exist. Thus, to continue increasing the level of integration, it is important to find a way 1) to control the power consumption and dissipation, 2) to increase the utilization of existing devices within the chip, and 3) to improve the efficiency of interconnect. Hybridization of nano electro mechanical switch (NEMS) with CMOS technology has been proposed to reduce the power consumption in some circuit modules by one to two orders of magnitude with a minimal cost at performance. NEMS-CMOS hybrid device technology appears to be an attractive option in terms of power management, but there are not enough learning on true nano scale NEMS device, which can be readily integrated with Si CMOS technology. In this talk, various options for NEMS-CMOS hybridization and associated challenges in materials and devices will be reviewed.
FEA Based Design Optimization of Exciting Sensitivity for Micromachined Beam Ultrasonic Transducer
Authors: Han Yanan , Cai Chenguang , Liu Yang , Salo Antti , Xu Leon , Xie Jilong
Published: March 2009

This paper presented a design optimization of piezoelectric micromachined ultrasonic transducer for its exciting sensitivity. A micromachined transducer is modeled as a large width-length ratio clamped-clamped beam, with the piezoelectric film to excite the beam vibration. The exciting sensitivity is taken as the optimization objective. Specifically, when the exciting voltage is fixed, the transducer structure is optimized to maximize the vibrating magnitude of the beam. The shape and the size of the piezoelectric layer are selected as the design parameters to optimize the exciting sensitivity of the transducer. In this paper, three different design variations of the piezoelectric layer structures are explored for the optimization. To perform the analysis and the subsequent optimization, the finite element models of the design options are created using ANSYS. The optimal design and the sensitivity analysis are performed; and the corresponding structural parameters of the piezoelectric film layer for optimal design are identified. Finally, we compare the optimization results of the exciting sensitivity for the large width-length ratio clamped-clamped beam based transducers of these three different piezoelectric layer structures; and the design method to improve the exciting sensitivity of the transducer is provided.
Global Simulation of CZ and FZ Bulk Crystal Growth: from Quasi-Dynamic and Dynamic Modelling to Process Control and Crystal Quality Optimization
Authors: Dupret Francois , Rolinsky Roman , Wu Liang , Loix Fabrice , De Potter Arnaud , Van den Bogaert Nathalie , Regnier Vincent
Published: March 2009

When Silicon ingots are grown for IC or PV applications, the crystal diameter has to conform to current market requirements while the crystal defects and composition have to be perfectly controlled. The present paper is devoted to illustrate CZ and FZ process optimization by use of the time-dependent FEMAG.2 software. First, the "off-line control" technique is devoted to determine the heater power and pull rate histories required to obtain a crystal of constant diameter and optimal quality by means of fully transient simulations. Other command parameters such as crystal and crucible rotation rates, magnetic field intensity, etc., can be optimized as well. Secondly, the use of quasi-dynamic numerical simulations shows very efficient to study the transient effects experienced by the system during bulk crystal growth, without necessitating a fully dynamic simulation. A main application of this technique is to improve the design of an automatic controller of the growth process.
Modeling Multi-Crystalline Silicon Growth in Directional Solidification Systems
Authors: Devulapalli Balaji , Kulkarni Milind
Published: March 2009

The key to achieving high solar cell efficiency is to increase average grain size in silicon multicrystals and reduce dislocation density. The grain size and dislocation distributions in a silicon multicrystal are strongly influenced by the design of the solidification furnace and the operating conditions during solidification. This paper discusses a reported mathematical model that quantifies the temperature field in the furnace, silicon melt flow distribution, and the shape of the melt/solid interface, which influences the grain size and dislocations distributions. The global model described here takes into account all modes of heat transfer coupled with turbulent melt and inert gas flows, and can be used to manipulate the growth conditions to produce silicon multicrystals of higher qualities. The numerical approach discussed in this paper can be used to evaluate changes in equipment design and process conditions to increase the solidification rate with acceptable compromise in the multicrystal quality.
Performance Limitations of mc-Si Solar Cells Caused by Defect Clusters
Authors: Sopori Bhushan , Rupnowski P. , Mehta V. , Budhraja V. , Johnston S. , Call N. , Mountinho H. , Al-Jassim M. , Shaikh A. , Seacrist M. , Carlson D.
Published: March 2009

Multicrystalline silicon wafers used for solar cells exhibit defect clusters-localized crystal defects in and near grains of some specific orientations. Defect clusters are also dominant sites for impurity precipitation, and they remain ungettered and unpassivated through the solar cell processing. This paper describes characteristics of defect clusters, and shows, through theory and experiment, that defect clusters typically lower cell efficiency by 3 to 4 absolute percentage points. To recover this efficiency loss, it is necessary to getter precipitated impurities.