bluuebunny/crossref_metadata_2025 huggingface dataset:
Self-Employed Mexican Immigrants Residing along the U.S.-Mexico Border: The Earnings Effect of Working in the U.S. versus Mexico
Authors: Mora Marie T.
Published: November 2006

This study uses U.S. census data from the year 2000 to analyze the earnings of Mexican immigrants along the U.S.-Mexico border while accounting for the location in which they work. The empirical results indicate that Mexican entrepreneurs who live in U.S.-border cities but primarily operate in Mexico accrue a significant earnings premium over their entrepreneurial and salaried counterparts working on the U.S. side of the border, even after controlling for differences in observable characteristics. This work-location earnings gap widens when focusing on Mexican business owners lacking U.S. citizenship. It follows that policies which reduce trade and labor flows across the U.S.-Mexico border may inadvertently dampen the entrepreneurial activities of foreign-born residents in U.S.-border cities.
The National Nanotechnology Initiative and the Social Good
Authors: Sandler Ronald , Kay W. D.
Published: November 2006

The United States federal government anticipates that nanotechnology will be the platform for the next technological and industrial revolution. The vision of its ongoing National Nanotechnology Initiative (NNI) is “a future in which the ability to understand and control matter on the nanoscale leads to a revolution in technology and industry.” The idea that nanotechnology is revolutionary has reached the public. In one public survey, over three-quarters of respondents answered correctly that “experts consider nanotechnology to be the next industrial revolution of the U.S. Economy.”

Labeling nanotechnology as “revolutionary” promotes a general attitude towards nanotechnology by trading on a common line of reasoning: technological revolutions are constituted by significant technological progress; technological progress enables comfort, ease, health, longevity, security and wealth; therefore, technological revolutions are social goods. Thus, to claim that nanotechnology is revolutionary invites a positive socio-ethical evaluation of it, not just a positive scientific or technological one.
Two Dobzhansky-Muller Genes Interact to Cause Hybrid Lethality in
Drosophila
Authors: Brideau Nicholas J. , Flores Heather A. , Wang Jun , Maheshwari Shamoni , Wang Xu , Barbash Daniel A.
Published: November 2006

The Dobzhansky-Muller model proposes that hybrid incompatibilities are caused by the interaction between genes that have functionally diverged in the respective hybridizing species. Here, we show that
Lethal hybrid rescue
(
Lhr
) has functionally diverged in
Drosophila simulans
and interacts with
Hybrid male rescue
(
Hmr
), which has functionally diverged in
D. melanogaster
, to cause lethality in F1 hybrid males. LHR localizes to heterochromatic regions of the genome and has diverged extensively in sequence between these species in a manner consistent with positive selection. Rapidly evolving heterochromatic DNA sequences may be driving the evolution of this incompatibility gene.
Tobacco industry litigation position on addiction: continued dependence on past views
Authors: Henningfield Jack E , Rose Christine A , Zeller Mitch
Published: November 2006

This paper reviews the tobacco industry’s litigation strategy for addressing the addiction issue through trial testimony by its experts, and opening and closing statements by its lawyers. Despite the fact that several companies now claim to accept, in varying degrees, the conclusions of the Surgeon General concerning tobacco addiction, the tobacco industry litigation strategy pertaining to addiction is essentially unchanged since that of the early 1980s when the issue emerged as crucial. The industry uses its experts and the process of cross-examination of plaintiff’s experts to imply that the addictiveness of tobacco and nicotine are more comparable to substances such as caffeine, chocolate, and even milk, than to heroin, cocaine and alcohol. Furthermore, the tobacco industry contends that the definition of addiction has now become so broadened as to include carrots and caffeine and hence that any concurrence that smoking is addictive, does not imply that cigarettes are addictive to the standards that drugs such as heroin and cocaine are addictive. Finally, the industry has continuously asserted that tobacco users assumed the risks of tobacco since they understood that quitting could be difficult when they began to use, and moreover, that the main barrier to cessation is lack of desire or motivation to quit and not physical addiction. These positions have been maintained through the 2004–2005 US Government litigation that was ongoing as the time of this writing.
Challenging the epidemiologic evidence on passive smoking: tactics of tobacco industry expert witnesses
Authors: Francis John A , Shea Amy K , Samet Jonathan M
Published: November 2006

Objective:To analyse the statements given by tobacco industry defence witnesses during trial testimonies and depositions in second-hand smoke cases and in parallel, to review criticisms of epidemiology in industry-funded publications in order to identify strategies for discrediting epidemiologic evidence on passive smoking health effects.

Methods:A collection of depositions and trial testimony transcripts from tobacco industry-related lawsuits filed in the United States during the 1990s, was compiled and indexed by the Tobacco Deposition and Trial Testimony Archive (DATTA). Statements in DATTA made by expert witnesses representing the tobacco industry relating to the health effects of passive smoking were identified and reviewed. Industry-supported publications within the peer-reviewed literature were also examined for statements on exposure misclassification, meta-analysis, and confounding.

Results:The witnesses challenged causation of adverse health effects of passive smoking by citing limitations of epidemiologic research, raising methodological and statistical issues, and disputing biological plausibility. Though not often cited directly by the witnesses, the defence tactics mirrored the strategies used in industry-funded reports in the peer-reviewed literature.

Conclusion:The tobacco industry attempted to redirect the focus and dialogue related to the epidemiologic evidence on passive smoking. This approach, used by industry experts in trial testimony and depositions, placed bias as a certain alternative to causation of diseases related to passive smoking and proposed an unachievable standard for establishing the mechanism of disease.
Prevalence of smoking among major movie characters: 1996–2004
Authors: Worth Keilah A , Cin Sonya Dal , Sargent James D
Published: November 2006

Background:Reports of a relationship between watching smoking in movies and smoking among adolescents have prompted greater scrutiny of smoking in movies by the public health community.

Objective:To assess the smoking prevalence among adult and adolescent movie characters, examine trends in smoking in movies over time, and compare the data with actual smoking prevalence among US adults and adolescents.

Design and methods:Smoking status of all major human adolescent and adult movie characters in the top 100 box office hits from 1996 to 2004 (900 movies) was assessed, and smoking prevalence was examined by Motion Picture Association of America (MPAA) rating and year of release.

Results:The movies contained 5944 major characters, of whom 4911 were adults and 466 were adolescents. Among adult movie characters, the overall smoking prevalence was 20.6%; smoking was more common in men than in women (22.6%v16.1%, respectively, p<0.001), and was related to MPAA rating category (26.9% for movies rated R (restricted, people aged <17 years require accompanying adult), 17.9% for PG-13 (parents strongly cautioned that some material might be inappropriate for children) and 10.4% for G/PG (general audiences, all ages; parental guidance suggested for children), p<0.001). In 1996, the smoking prevalence for major adult movie characters (25.7%) was similar to that in the actual US population (24.7%). Smoking prevalence among adult movie characters declined to 18.4% in 2004 (p for trend <0.001), slightly below that for the US population for that year (20.9%). Examination of trends by MPAA rating showed that the downward trend in smoking among adult movie characters was statistically significant in movies rated G/PG and R, but not in those rated PG-13. A downward trend over time was also found for smoking among adolescent movie characters. There was no smoking among adult characters in 43.3% of the movies; however, in 39% of the movies, smoking prevalence among adult characters was higher than that in the US adult population in the year of release.

Conclusions:Smoking prevalence among major adolescent and adult movie characters is declining, with the downward trend among adult characters weakest for PG-13-rated movies. Although many movies depict no adult smoking, more than one third depict smoking as more prevalent than that among US adults at the time of release.
Smokers living in deprived areas are less likely to quit: a longitudinal follow-up: Table 1
Authors: Giskes Katrina , van Lenthe Frank J , Turrell Gavin , Brug Johannes , Mackenbach Johan P
Published: November 2006

Objective:To follow up smokers to examine whether the likelihood of quitting smoking varied by area deprivation, and whether smoking history, health status, personality characteristics, social support and stressful situations contributed to differences in area deprivation in quit rates.

Design:Longitudinal data with a 6-year follow-up period were analysed using multilevel logistic regression. Area-level deprivation was characterised by a composite measure that was the sum of the proportion of unemployed residents, the percentage of residents in blue-collar occupations and the proportion with only elementary-level education. Previously established predictors of smoking cessation, including education, age at smoking initiation, self-assessed health, chronic illness, locus of control, neuroticism, negative life events, longlasting relationship difficulties, emotional social support and negative neighbourhood conditions were examined separately and in a combined model to assess whether they contributed to neighbourhood deprivation differences in quitting.

Participants:404 participants (residing in 83 areas) identified as smokers at baseline and who did not change their residential address over the follow-up period.

Main outcome:Being a non-smoker at follow-up.

Results:Odds ratios of quitting decreased with greater area-level deprivation, but differences reached significance only between the most and least deprived quartiles. Smoking history, health status, personality characteristics, social support and stressful situations did not contribute to the lower quitting rates seen among smokers in deprived areas.

Conclusions:Living in a deprived area seems to reduce the likelihood of quitting smoking; hence individual-level tobacco control efforts should be complemented with area-based interventions. However, we need to identify and understand the underlying factors associated with living in a deprived area that contributes to lower quitting rates.
The role of tobacco advertising and promotion: themes employed in litigation by tobacco industry witnesses: Table 1
Authors: Goldberg Marvin E , Davis Ronald M , O’Keefe Anne Marie
Published: November 2006

Objectives:To identify key themes related to tobacco advertising and promotion in testimony provided by tobacco industry-affiliated witnesses in tobacco litigation, and to present countervailing evidence and arguments.

Methods:Themes in industry testimony were identified by review of transcripts of testimony in the Tobacco Deposition and Trial Testimony Archive (http://tobaccodocuments.org/datta) from a sample of defence witnesses, including three academic expert witnesses, six senior executives of tobacco companies, and one industry advertising consultant. Counterarguments to the themes embodied in defence testimony were based on information from peer-reviewed literature, advertising trade publications, government reports, tobacco industry documents, and testimony provided by expert witnesses testifying for plaintiffs.

Results:Five major themes employed by defence witnesses were identified: (1) tobacco advertising has a relatively weak “share of voice” in the marketing environment and is a weak force in affecting smoking behaviour; (2) tobacco advertising and promotion do not create new smokers, expand markets, or increase total tobacco consumption; (3) the tobacco industry does not target, study, or track youth smoking; (4) tobacco advertising and promotion do not cause smoking initiation by youth; and (5) tobacco companies and the industry adhere closely to relevant laws, regulations, and industry voluntary codes. Substantial evidence exists in rebuttal to these arguments.

Conclusions:Tobacco industry-affiliated witnesses have marshalled many arguments to deny the adverse effects of tobacco marketing activities and to portray tobacco companies as responsible corporate citizens. Effective rebuttals to these arguments exist, and plaintiffs’ attorneys have, with varying degrees of success, presented them to judges and juries.
Terrane-specific rock magnetic characteristics preserved in glacimarine sediment from southern coastal Alaska
Authors: Cowan Ellen A , Brachfeld Stefanie A , Powell Ross D , Schoolfield Stephanie C
Published: November 2006

Sediments deposited in three fjord systems latitudinally spanning the northeast Gulf of Alaska coastline have distinctive rock magnetic characteristics that are derived from glacially eroded accreted terranes. Ideal conditions exist in coastal Alaska to preserve primary rock magnetic properties within the sediment record because of the dominance of glacial erosion and rapid sediment transportation and burial. In temperate glacially dominated marine settings, terrigenous sediment is not diluted by biogenic material and diagenetic alteration is minimal. The juxtaposition of temperate glaciers on the northwest-trending accreted terranes of the southern Alaska continental margin provides magnetic provenance tracers of sediment derived from this region that can aid in the interpretation of glacial, paleoclimate, and tectonic proxy records from marine sediment. Holocene sediment deposited in Glacier Bay is eroded from the Craig subterrane of the Alexander terrane; it is characterized by high-volume magnetic susceptibility and coarse-grained, pseudosingle-domain (PSD) and multidomain (MD) magnetite. In Yakutat and Disenchantment bays, farther to the north, glaciers also erode the Yakutat and Chugach terranes. There, sediment contains slightly finer-grained PSD and MD magnetite, which is chemically distinct from that of Glacier Bay. In the northern-most sector, sediment is eroded from the Chugach terrrane in Harriman and College fiords, adjacent to Prince William Sound. These sediments have low magnetic susceptibility and contain micron-size pyrrhotite.
FILAMENT ORDERING AND CLUSTERING BY MOLECULAR MOTORS IN MOTILITY ASSAYS
Authors: KIERFELD JAN , KRAIKIVSKI PAVEL , LIPOWSKY REINHARD
Published: November 2006

We study the cooperative behavior of cytoskeletal filaments in motility assays, in which immobilized motor proteins bind the filaments to a surface and actively pull them along this surface. Because of the repulsive interaction of filaments, the motor-driven dynamics of filaments leads to a nonequilibrium phase transition which generalizes the isotropicnematic phase transition of the corresponding equilibrium system, the hard-rod fluid. Langevin dynamics simulations and analytical theory show that the motor activity enhances the tendency for nematic ordering. At high detachment forces of motors, we observe the formation of filament clusters because of blocking effects; at low detachment forces, cluster formation can be controlled by the density of inactive motors.
Discovery and Biology of IL-23 and IL-27: Related but Functionally Distinct Regulators of Inflammation
Authors: Kastelein Robert A. , Hunter Christopher A. , Cua Daniel J.
Published: November 2006

Long-term resistance to many infections depends on the innate ability of the immune system to coordinate the development of antigen-specific adaptive responses. Deficiencies in these events can result in increased susceptibility to pathogens, whereas an inability to regulate an appropriate response can lead to devastating pathological conditions. For over a decade, interleukin (IL)-12 has been recognized as the canonical cytokine that links innate and adaptive immunity, and with the discovery of IL-23 and IL-27 as cytokines related to IL-12, there has been a concerted effort to understand the relationship between these factors. The results emerging from these studies have provided fundamental new insights into the developmental pathways that promote the differentiation and function of CD4+T helper cells and offer a dramatically altered perspective on the cause and prevention of autoimmune disease. In this review, we aim to highlight the discoveries that have led to our current understanding of the biology of IL-23 and IL-27 in the context of their role in resistance to infection, immune-mediated inflammation, and cancer.
Effector and Memory CTL Differentiation
Authors: Williams Matthew A. , Bevan Michael J.
Published: November 2006

Technological advances in recent years have allowed for an ever-expanding ability to analyze and quantify in vivo immune responses. MHC tetramers, intracellular cytokine staining, an increasing repertoire of transgenic and “knockout” mice, and the detailed characterization of a variety of infectious models have all facilitated more precise and definitive analyses of the generation and function of cytotoxic T lymphocytes (CTL). Understanding the mechanisms behind the differentiation of effector and memory CTL is of increasing importance to develop vaccination strategies against a variety of established and emerging infectious diseases. This review focuses on recent advances in our understanding of how effector and memory CTL differentiate and survive in vivo in response to viral or bacterial infection.
Electrical and Structural Properties of High-K HfO2 on Si1-X Gex Substrates
Authors: Hwang C.S. , Park Taejoo , Kim Jeong Hwan , Hong Sug H. , Seo Minha , Jang J.H H.
Published: November 2006

The changes in the electrical and physical properties of HfO2 films grown using atomic layer deposition (ALD) on Si1-XGeX (x=0.1, 0.2, 0.3) substrates after post-annealing have been studied. The migration of Ge plays a key role in reducing the capacitance equivalent thickness (CET) whilst keeping the leakage current density constant after post-annealing. The Ge atoms which have already diffused into the HfO2 upper layer during deposition are drawn back to interfacial layer. Although the thickness of interfacial layer increases, the thickness shrinkage of HfO2 upper layer and increased permittivity of both layers achieves a reduction of the capacitance equivalent thickness.
High-k Materials for Tunnel Barrier Engineering in Floating-Gate Flash Memories
Authors: Blomme Pieter , Govoreanu Bogdan , Rosmeulen Maarten , Akheyar Amal , Haspeslagh Luc , De Vos Joeri , Lorenzini Martino , Van Houdt Jan , De Meyer Kristin
Published: November 2006

Replacing the tunnel oxide or interpoly dielectric of a floating gate Flash memory cell by an engineered tunneling barrier allows lowering the voltage necessary to program or erase the memory cell. We use dual layer dielectric stacks with different dielectric constant, allowing a high tunneling current at relatively low applied voltage while providing good data retention. Stacks consisting of SiO2 with HfO2 or Al2O3 have been studied in single poly memory cells, demonstrating both low voltage programming by tunneling and 10 years of data retention. These stacks have also been integrated as interpoly dielectric (IPD) in a 0.18μm HIMOSTM process for low voltage erasing by tunneling through the IPD.
Investigation of Current Conduction Mechanism in HfO2 Stack Structures
Authors: Chiou Yun-Leei , Gaddipati Surendra , Mansouri Mehdi , Jeedigunta Sathyaharish , Kumar Ashok
Published: November 2006

The current conduction mechanism is studied for HfO2 with single layer and high-k stack structures. The conduction mechanism is attributed to the Poole-Frenkel emission in high- k dielectrics. The deviation in the slope of the Poole-Frenkel plot is attributed to the interfacial layer and the method of measurement. The oxide layers play an important role in the determination of the electrical properties of high-k stack in the high field regions. The oxide layers are also responsible for the breakdown with a negative coefficient of breakdown voltage.
A Novel Iridium Precursor for MOCVD
Authors: Kawano Kazuhisa , Furukawa Taishi , Takamori Mayumi , Tada Ken-Ichi , Yamakawa Tetsu , Oshima Noriaki , Fujisawa Hironori , Shimizu Masaru
Published: November 2006

Physical properties and deposition characteristics of a newly developed liquid iridium precursor Ir(EtCp)(C2H4)2 for MOCVD were examined. TG curve showed the excellent volatility and DSC curve showed lower decomposition temperature than previous precursors. Ir-based films were deposited on SiO2/Si substrates by MOCVD using Ir(EtCp)(C2H4)2 - O2 sysytem. Ir films were successfully deposited without obvious incubation time at an initial growth stage at a deposition temperature of 250{degree sign}C. IrO2 films can be obtained directly on SiO2/Si substrate at a deposition temperature of 400{degree sign}C by controlling O2 concentration.
Compatibility of High K Dielectric with TiCl4 Based TiN for MIS Storage Capacitors for sub 70 nm DT DRAM Technology and Beyond
Authors: Gay Xavier , Hintze Bernd , Erben Elke , Bernhardt Henry , Kudelka Stephan P. , Goupil Christophe , Mercey Bernhard
Published: November 2006

The introduction of high K dielectrics in combination with metal electrodes in deep trench (DT) DRAM storage capacitors for technology beyond 70nm ground rule is mandatory. In this paper, we study the compatibility of TiCl4-based TiN electrodes with two dielectric materials (Al2O3 and HfSiOx). The impact of the applied thermal budget on the electrical properties and the role of residual chlorine in the electrode are investigated. Compatibility of the dielectrics with the TiN deposition process is also studied. For the Al2O3/TiN system, high temperatures and high chlorine concentration lead to degradation of capacitance and leakage current. HfSiOx dielectric is less sensitive to the chlorine concentration in the electrode. Exposure of the dielectric to the TiCl4 precursor leads to degradation of the electrical properties for the both high K materials.
Doped HfO2 for Higher-k Dielectrics
Authors: Toriumi Akira , Kita Koji , Tomida Kazuyuki , Yamamoto Yoshiki
Published: November 2006

In this work, we discuss doping effects of other metal oxides into HfO2 as a function of annealing temperature or doping concentration, and demonstrate a dramatic change of dielectric properties of doped HfO2 films. In addition to the relative dielectric constant (k-value), crystallization/amorphous characteristics have been also studied. One case induces easier crystallization than the pure HfO2, while the other case keeps amorphous up to 900 ºC without nitrogen introduction. From those observations, we discuss a general guideline for obtaining higher-k dielectric films.
High-Temperature Processing Effects on Lanthanum Silicate Gate Dielectric MIS Devices
Authors: Lichtenwalner Daniel J. , Jur Jesse , Inoue Naoya , Kingon Angus
Published: November 2006

The high-temperature stability of MIS devices based on lanthanum silicate having sub-nm (0.6 - 0.7 nm) EOT values are reported. After a 1000{degree sign}C, 10 s RTA treatment, devices with Ta gate metal undergo an EOT increase to 1.57 nm or higher, while devices having TaN as the gate electrode retain an EOT as low as 1.12 nm. An EOT under 1.0 nm is achieved if the 1000{degree sign}C RTA is reduced to 5 s, with a corresponding gate leakage of 0.1 A/cm2. Medium energy ion scattering and X-ray diffraction analysis reveal that the Ta gate metal undergoes a phase change and reaction above 800{degree sign}C, while for TaN no change in the XRD spectrum is detected. Interface state defect densities and leakage currents are reduced after the high temperature processing. Results reveal the importance of the entire gate stack design and processing in obtaining good device properties.
Thermal Robustness of VFB and EOT in HfOx(N) p-MOS Devices with Partially Silicided Pt Gate Electrodes
Authors: Kadoshima Masaru , Nabatame Toshihide , Takahashi Masashi , Ogawa Arito , Iwamoto Kunihiko , Mizubayashi Wataru , Ota Hiroyuki , Satake Hideki , Toriumi Akira
Published: November 2006

We investigated the process window of partially silicided (PASI) Pt gate electrodes which can effectively suppress unintentional threshold voltage increases of Hf-based high-k p- MOSFETs, and the impact of application of the PASI Pt (PASI- PtSi) gate electrode on their electrical properties. The values of the EOT, flat-band voltage, and the gate leakage current density of the HfOx(N) p-MOS capacitors with the PASI- PtSi gate electrodes are almost identical when the Pt film is more than double the thickness of the poly-Si films at silicidation temperatures from 400 to 600ºC. No degradation in the gate leakage current density of the HfOx(N) MOS capacitors with the PASI-PtSi gate electrodes was observed, compared with the FUSI-NiSi and FUSI-PtSi gate electrodes. Consequently, it is concluded that the PASI technology is useful in scaled CMOS devices with Hf-based high-k dielectrics.
Advanced Nano-analysis of High-k Dielectric Stacks
Authors: MacKenzie Maureen , Craven Alan , McComb David , De Gendt S.
Published: November 2006

Analytical electron microscopy techniques are used to investigate elemental distributions across high-k dielectric stacks with metal gates. Electron energy loss spectroscopy results from Si(100)/SiO2/HfO2/TiN and Si (100)/SiO2/HfO2/TiN/poly-Si gate stacks show evidence of interface reactions having occurred at the TiN/poly-Si interface and possibly at the HfO2/TiN interfaces. As such, this technique offers unique capabilities to further improve understanding of the work function behavior of metal gate electrode/dielectric stacks to be used in future CMOS technologies.
Effect of a Se Monolayer on Interface Properties Between Al2O3 and n-type Si(100)
Authors: Larrieu Guilhem , Tao Meng , Moumem Naim , Song Guanghua , Moldonado Eduardo , Kirk Wiley P.
Published: November 2006

An in-situ high-vacuum process has been developed for the preparation of ultrathin Al2O3 films on monolayer Se passivated Si(100) surface. The in-situ high-vacuum process prevents the Si surface from adsorbed moisture or native oxide, leading to an Al2O3/Si(100) interface without any low-k interfacial layer at 400oC. The Se monolayer terminates the dangling bonds on Si(100) before the formation of the high-k dielectric. The electrical properties of the Al2O3 film on Se passivated Si(100) are significantly improved in comparison to control samples without Se passivation. The interface trap density is about 5 times lower to 2×1011 eV-1/cm2. The C-V hysteresis is reduced to 80 mV from 160 mV. The leakage current for the same physical dielectric thickness is reduced by more than an order of magnitude.
Influence of Deposition Temperature of Atomic-Layer-Deposited HfO2 Films on Interfacial Chemical Structure and Interface Trap Density
Authors: Kim Jeong Hwan , Park Taejoo , Hwang C.S. , Hong Sug H. , Seo Minha
Published: November 2006

The influence of the deposition temperature (250oC and 300oC) and oxidant (O3) concentration during atomic layer deposition of HfO2-gate dielectrics on the dielectric performance of the films grown on Si using Hf([N(CH3)(C2H5)]3[OC(CH3)3]) or Hf[N (CH3)2]4 as the Hf-precursor was studied. In case of HfO2 thin films, the deposition temperature affects the interfacial trap density (Dit): The lower the deposition temperature is, the better is Dit. Investigation of the interface states using X- ray photoelectron spectroscopy revealed that HfO2 thin films that show a lower Dit include more SiN and silicate relative to SiO2. The depth profiles of the chemical composition of the film stacks taken by secondary ion mass spectroscopy confirmed that silicate reaction was predominant over the re-oxidation reaction of Si substrate. Judging from this, a better interface property can be obtained at a lower deposition temperature due to the densely formed SiN layer and the predominant silicate reaction which suppress a harsh re- oxidation (Si4+) in the interface.
A Simple Approach to Reduce Interlayer Formation of Sputtered Hf-Based Gate Dielectrics by Nitrogen Incorporation
Authors: Chen Jen-Sue , Lu Cheng-Hsueh , Lai Yi-Sheng
Published: November 2006

In this work, we have demonstrated a simple approach to suppress interfacial layer (IL) formation for HfOx and HfOxNy gate dielectrics by sputtering HfOx and HfNx films, respectively, followed by further annealing. The material characteristicsof dielectric films were investigated by glacing incident angle X-ray diffraction (GIAXRD), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry. Both HfOx and HfOxNy films show amorphous structures after annealing up to 700 oC; nevertheless, the HfOxNy film presents the superiority to prevent interfacial layer (IL) formation over the HfOx film. Formation of a self-doped nitrogen-contained IL in the HfOxNy dielectric stack is detected by XPS analysis. Furthermore, the HfOxNy dielectric layer presents higher refractive index (about 2.0) than that of HfOx (about 1.8) in the range of visible light, indicating its denser structure.
Growth Studies and Reaction Mechanism of the Atomic Layer Deposition of Hafnium Oxide
Authors: Delabie Annelies , Caymax Matty , Brijs Bert , Brunco David , Conard Thierry , Sleeckx Erik , Ragnarsson Lars-Ake , Van Elshocht Sven , De Gendt Stefan , Heyns Marc
Published: November 2006

The implementation of HfO2 gate dielectrics in sub-45 nm devices requires optimization of nanometer-thin HfO2 layers, deposited e.g. by Atomic Layer Deposition (ALD). In this work, we optimize the ALD conditions such as precursor pulse time and deposition temperature for HfO2 layers with physical thickness below 2 nm. Additionally, we investigate intermediate treatments in the ALD reaction cycle, such as exposure to gas phase moisture or remote plasma at low temperature and thermal anneals. Such intermediate treatments affect both growth-per- cycle (GPC) and impurity content of the HfO2 layers. The impact of these process modifications allows a better understanding of the reaction mechanisms in the HfCl4/H2O ALD process. Improvements in growth behavior result in better electrical performance, e.g. better scalability of Equivalent Oxide Thickness (EOT) and reduced leakage current as compared to the conventional process indicating better HfO2 film quality.
Evaluation of Nb(Si)N as Metal Gate Material
Authors: Van Hoornick Nausikaa , De Witte Hilde , Witters Thomas , Zhao Chao , Conard Thierry , Huatori Hannu , Swerts Johan , Schram Tom , Maes Jan Willem , De Gendt Stefan , Heyns Marc
Published: November 2006

Nb(Si)N films deposited by thermal atomic layer deposition (ALD) have been investigated as potential gate electrode materials in advanced CMOS devices. The NbN films were deposited at 400ºC using NbCl5 and NH3 as precursors. For NbSiN, SiCl4 was added as a precursor, yielding an average silicon content of 3 at% [ ]. The work function of these films was determined by high-frequency capacitance voltage measurements on two thickness series, one of thermal oxides (6.5 to 20nm) and one of ALD HfO2 (2 to 6nm) followed by an O2 post deposition anneal (PDA). It was found that NbN has a work function of ~4.7 eV on SiO2 and ~4.9eV on HfO2. However, thermal stability is limited to ~950ºC. The thermal stability on SiO2 is increased by incorporation of silicon into the NbN. NbSiN has a work function ~4.7 eV on SiO2 and ~4.8eV on HfO2.
Impact of Al, Ni, and TiN Metal Gates On ZrO2-MOS Capacitors
Authors: Abermann Stephan M. , Efavi Joseph , Lugstein Alois , Auer Erwin , Gottlob Heiner , Schmidt Mathias , Lemme Max , Bertagnolli Emmerich
Published: November 2006

We compare the impact of Aluminum, Nickel and Titanium-Nitride as gate materials on MOS caps incorporating metal organic chemical vapor deposited (MOCVD) ZrO2 .Post metallization annealing in forming gas atmosphere on the electrical characteristics of the various gate stacks is a further issue. Aluminum was primarily investigated as a reference material. Whereas TiN-stacks show very promising electrical characteristics necessary for future CMOS devices, Ni-MOS caps exhibit an undesired high frequency behavior.
Post Metallization Anneal Effects in HfO2 Based Capacitors with Various Gate Electrodes
Authors: Lu Yi , Buiu Octavian , Mitrovic Ivona , Hall Stephen , Chalker Paul R. , Potter Richard , Nazarov Alexei , Lysenko V. , Tyagulskii I. , Osiyuk I. , Vovk Ya.
Published: November 2006

Metal-oxide-semiconductor (MOS) capacitors based on HfO2 gate stacks with various metal and metallic compound gates are compared to study the impact of the gate electrode materials. We find the oxide charges in these capacitors are located at the interface between the HfO2 layer and the interfacial layer. The capacitor with nickel silicides gate exhibits highest oxide charge density due to interfacial reactions at the NiSi/high - k layer interface. In addition, a comparative analysis of the post-metallization anneal effects on the interfaces of the MOS capacitors is presented.
Study of Charge and Inversion Layer Mobility in Hafnium Oxide Stacks
Authors: Zhang Zhihong , Li Min , Campbell Stephen
Published: November 2006

Charge in HfO2 gate stacks grown from various MOCVD sources has been studied. For these films, charge in the stack is mainly concentrated at the interfaces between the layers and is negative at the HfO2/interfacial layer (IL) interface and positive at the Si/IL interface. A forming gas anneal (FGA) can reduce interface charge, hysteresis, and interface state densities. The marked difference in the post deposition annealing (PDA) response of similar films deposited from different precursors, however, strongly suggests that charge in these stacks is related to the deposition chemistry and may be due to residual impurities or defects left in the film from the deposition. The study on the inversion layer mobility indicates that coulomb scattering due to interface trapped charge accounts mainly for the hole mobility degradation. Electron mobility experiences much more severe degradation than hole mobility, suggesting the existence of multiple scattering sources.
Charge Trapping & NBTI in High k Gate Dielectric Stacks
Authors: Zafar Sufi , Callegari Alessando , Stathis James
Published: November 2006

Over recent years, there has been increasing research and development efforts to replace SiO2 with high dielectric constant (k) materials such as HfO2, HfSiO, Al2O3. An important transistor reliability issue is the threshold voltage stability under prolonged stressing. In this paper, we discuss two main causes of threshold voltage instability: charge trapping and negative bias temperature instability (NBTI) in high k gate dielectric stacks. Experimental and modeling studies for these threshold voltage instabilities are reviewed.
Charge Capture Kinetics of Nitride Trap in Oxide-Nitride-Oxide Structures
Authors: Cho Hoon Young , Park Chan Jin , Oh Hyung Taek , Kwak Dong Wook , Lee Youn Hwan , Yang Woo Choel , Kim Chung Woo
Published: November 2006

Oxide-Nitride-Oxide (ONO) structures have been fabricated on n- and p-type Si (001) substrates for a volatile memory application. Capacitance-voltage hysteresis is measured for the capacitors fabricated with the ONO structures. The difference of the flat band voltage is about 9.0V for the p-type substrates and 7.2V for the n-type substrates, respectively. Deep level transient spectroscopy is employed to investigate the energy levels of the charge traps and the capture kinetics of charge carriers in the ONO structures. The hole traps are observed to be at 2.44eV above the valence band maximum of the nitride layer or 0.24 eV above the valence band maximum of Si. The trap amplitude is found to be dependent upon the logarithm of the filling pulse time in the ranges from 10^-5 to 10^-2 s. This suggests that the charge traps in SONOS can be distinctly classified by investigating the capture kinetics of charges.
Implications of Non-Linear Poole-Frenkel Plots on High-k Dielectric Leakage
Authors: Harrell William R. , Cordella Thomas , Poole Kelvin
Published: November 2006

The implications of a modern model of the Poole-Frenkel (PF) effect on the characterization of high-k dielectric leakage are investigated. The classical PF model predicts a characteristic graph known as the PF plot which is linear for all fields, and a single linear region on such a plot of measured current is taken as evidence of PF emission. However, the modern model of the PF effect, incorporating the Fermi-Dirac function, is more accurate, and we show that this model predicts non-linear PF plots. The implications for characterizing dielectric leakage with the modern model are discussed. Observation and characterization of a non-linear PF plot of measured leakage current in thin Al2O3 films is presented.
Charge Trapping: A Major Reliability Challenge for High-k Gate Dielectrics
Authors: Ma T.P. , Wang Sharon , Song Liyang , Bu Huiming
Published: November 2006

This paper focuses on a major reliability issue for Hf-based high-k gate dielectrics. It will show that (1) the operating lifetime extracted from the trapping induced threshold voltage shift, Delta-Vth, is much shorter than that extracted from Time-Dependent Dielectric Breakdown, and therefore the actual device lifetime is limited by charge trapping; (2) Biased in inversion, electron trapping is the dominant mechanism for nMOSFETs; hole trapping is the dominant mechanism for pMOSFETs at low voltages (< 2 eV); (3) for pMOSFETs biased at high voltages (> 2.6 V), either net electron trapping or net hole trapping are observed, depending on the details of the stress conditions; (4) the above can be explained by the electron and hole currents through the dielectric for a given stress condition; (5) electron traps (with the energy level at ~0.68eV below Ec of the dielectric) give rise to Frenkel-Poole (F-P) conduction; (6) hole traps do not participate in F-P conduction in the temperature range studied (300-500 k).
Salient Features in the Capacitance Characteristics of Ultrathin High-K Devices
Authors: Kar S. , Reddy Dharmendar , Rawat Surendra
Published: November 2006

Salient features of MOS (Metal Oxide Silicon) devices with ultra-thin high-Κ gate dielectrics are outlined here, which include the following. In the case of the ultra-thin (EOT < 2 nm) gate dielectrics, the capacitance-voltage (C-V) and the surface potential versus bias characteristics are dominated by the accumulation and the strong inversion regimes, in contrast to the case of the thicker gate dielectrics, where these characteristics are dominated by depletion and weak inversion regimes. In the strong accumulation regime, the experimental lnCp versus the surface potential plot (Cp is the sum of the space charge capacitance Csc and the interface trap capacitance Cit) was found to be a straight line, and its slope varied strongly with the gate dielectric material and was found to be inversely proportional to [square root(Pbm*/m)]K/Cdi, where Pb is the conduction/valence band offset, m* is the effective electron/hole tunneling mass, K is the dielectric constant, and Cdi is the gate dielectric capacitance.
Indication of Lateral Nonuniformity of Effective Oxide Charges in High-k Gate Dielectrics by Terman's Method
Authors: Hwu Jenn-Gwo , Huang Szu-Wei
Published: November 2006

The Terman's method for interface trap density (Dit) extraction is utilized to examine the existence of lateral non- uniformity (LNU) of effective oxide charges in MOS(n) capacitors. The two parallel capacitors model is constructed to simulate the LNU charges, and it was shown that negative effective Dit appears when LNU charges exist in gate oxide. This technique was used to detect the extent of the non- uniformity of effective oxide charge distribution in Al2O3 high-k gate dielectrics prepared by nitric acid (HNO3) oxidation of ultra-thin Al films deposited on semiconductor substrates. It was found that LNU charges exist in Al2O3 experimentally and this observation is in agreement with the simulation result.
ALD: Emerging Materials, Processes, and Nanoscale Technology Applications
Authors: Eisenbraun Eric , Carpenter Michael , Siddique Rezina , Naczas Sebastian , Zeng Wanxue , Luo Fu , Kaloyeros Alain
Published: November 2006

Nanoscale (zero-thickness) thin film growth processes such as atomic layer deposition are under extensive development for potential use in key nanoelectronics applications. The unique characteristics of these processes make them potentially enabling for a number of emerging nanotechnology-driven technologies. This paper discusses several of these potential applications and highlights specific fields where ALD is being researched.
Iridium Barriers for Direct Copper Electrodeposition in Damascene Processing
Authors: Josell Daniel , Bonevich John , Moffat Thomas , Aaltonen Titta , Ritala Mikko , Leskelä Marku
Published: November 2006

Seedless superfilling by copper electrodeposition is demonstrated on sub-micrometer trenches with Ir barrier layers deposited by atomic layer deposition. The Cu deposition is seen to occur smoothly and continuously on the Ir without the benefit of a copper seed layer. The work supports efforts to develop diffusion barriers compatible with seedless superfill for damascene fabrication of interconnects. It also indicates the suitability of atomic layer deposition for fabrication of barrier layers, in this case Ir, for seedless processing.
Chemical Compatibility and Vapor Phase Stability Considerations for ALD Processes Utilizing Hafnium, Titanium, and Silicon Amide Precursors
Authors: Meiere Scott H. , Peck John , Litwin Michael
Published: November 2006

When utilizing metal amide compounds as ALD precursors, a number of chemical properties must be considered. Two of these properties are chemical compatibility and vapor phase thermal stability. The former relates to utilizing precursors together to form ternary films (e.g., hafnium silicates, hafnium titanates) where premature side reactions may cause inconsistent delivery or growth rate. The latter must be understood to prevent deviation from self-limiting processes resulting from unwanted thermal decomposition. The importance of both of these factors makes proper precursor selection essential for a successful ALD process, and therefore provides the impetus for the studies herein.
Atomic Layer Deposition of NbN and Nb(Si)N for Metal Electrodes
Authors: Huotari Hannu , Haukka Suvi , Matero Raija , Rahtu Antti , Tois Eva , Tuominen Marko
Published: November 2006

Niobium nitride NbN and niobium silicon nitride Nb(Si)N were deposited by Atomic Layer Deposition (ALD) from niobium pentachloride NbCl5, silicon tetrachloride SiCl4, and ammonia NH3. It was shown that low resistivity NbN can be more readily processed by ALD than low resistivity TaN using just NH3 as reducing agent. Silicon could be uniformly added into the NbN structure, and increase in silicon content increased the resistivity of the films due to silicon incorporation as silicon nitride. A successful scale-up onto 200 mm wafer was performed for both processes.
Modeling Backward Wave Oscillations in a High Gain TWT
Authors: Kumar Vikas , Vohra Anil
Published: November 2006

Conditions of backward wave oscillations have been modeled in a in a Helix TWT based upon the two wave theory. The case of both a tapered and un-tapered helix structure have been studied to find the dependence of the start oscillation current on different design parameters. A 140 Watt, Ku-Band, Space TWT has been analyzed for different design parameters and the beam voltages to calculate the start oscillation current in the different sections taking actual pitch profile. The start oscillation current is the most critical parameter regarding the backward wave oscillations and hence in ensuring the stability of a high gain TWT
Fabrication of Poly-Si TFT on Glass Using Scanning RTA and Light Absorption Layer
Authors: Pyo Yu-Jin , Kim Min-Sun , Yoon Yeo-Geon , Joo Seoun Ki
Published: November 2006

In this study, we used scanning rapid thermal annealing (RTA) and a new structure of thin film transistor (TFT), which was inserted a light absorption layer into, in order to increase the growth rate of metal-induced lateral crystallization (MILC). Amorphous silicon film was radiated by a halogen lamp and transformed into poly crystalline silicon by MILC. We investigated the light absorption layer effect on MILC growth and TFT performance. TFT using scanning RTA and the light absorption layer has better electrical properties than the conventional one. By this method, we could reduce crystallization time and obtain good electrical properties. Also, during the fabrication process of TFT, glass substrates were not bent or wrapped.
A Microfabricated Nickel-Hydrogen Battery Using Thick Film Printing Techniques
Authors: Tam Waiping Gloria , Wainright Jesse S.
Published: November 2006

To utilize the distinctive cycle life and safety characteristics of the nickel-hydrogen chemistry while eliminating conventional high pressure limitations, a microfabricated nickel-hydrogen battery using low-pressure metal hydride for hydrogen storage was proposed. Thick film printing techniques which are simple and low cost were used to fabricate this proposed battery. Inks were developed for the different battery components, including electrodes, current collectors and separator, and SEM images on these printed components showed the desired characteristics for each. Positive electrode cycling tests were performed on the printed positive electrodes while cyclic voltammetry was used to characterize the printed negative electrodes. Consistent charge and discharge performance was observed during positive electrode cycling. Full cells with printed positive and negative assemblies were assembled and tested for cycling.
Entropymetry of Lithium Intercalation in Spinel Manganese Oxide: Effect of Lithium Stoichiometry
Authors: Yazami Rachid , Reynier Yvan , Fultz Brent
Published: November 2006

Cathodes based on cubic (spinel) structure LiMn2O4 were investigated by electrochemical entropymetry in an attempt to characterize their phase diagram according to the initial lithium composition. The stoichiometric material shows a very pronounced 2-phase region in the high 4V plateau and a solid- solution behavior in the lower 4V plateau. A third region is found in the non stoichiometric material characterized by a steep increase in entropy. This may relate to the onset of a stoichiometry induced anticipated cubic to tetragonal phase transition in the 4V area in this material. The later has been so far reported to occur only in the 3V area.