bluuebunny/crossref_metadata_2025 huggingface dataset:
Theological Aesthetics and Revelatory Tension
Authors: O'Connor John D
Published: February 2008

Much contemporary theological aesthetics treats beauty as straightforward. This is, however, to neglect tensions in our experience and understanding of beauty. The issue of these tensions arises in the examination of the role of the imagination in the epistemology of beauty, as well as in the examination of the relationships between beauty and truth, and beauty and goodness. The treatment of these relationships in the work of Kant and Maritain is assessed. The aesthetics of Kant and Maritain are classic attempts to address and even overcome the tensions in these relationships, but on close examination fail to do so. That writers whose works are often cited in favour of clear-cut positions do not resolve these tensions, and that questions raised by these issues fail to go away, supports the view that these tensions are inherent in our experience and understanding of beauty. If so, and if beauty is understood as in some way revelatory of the divine, it follows that there are tensions inherent in our experience and understanding of beauty as revelatory. Such tensions need to be incorporated into theological aesthetics.
Effect of inorganic polyphosphate in periodontitis in the elderly
Authors: Yamaoka Minoru , Uematsu Takashi , Shiba Toshikazu , Matsuura Takashi , Ono Yuusuke , Ishizuka Masahide , Naramoto Hiroko , Takahashi Masahiro , Sugiura‐Tomita Maki , Iguchi Kousei , Yamashita Shuichiro , Furusawa Kiyofumi
Published: February 2008

Aim: Inorganic polyphosphate exists as chains of phosphate molecules and is distributed in osteoblasts, and regulates osteoblastic cell differentiation and bone matrix calcification. The purpose of this study was to clarify the effects of inorganic polyphosphate on periodontitis.

Material and methods: Subgingival local irrigation with inorganic polyphosphate was studied in a randomised double‐blind study of 33 patients with periodontitis. Scaling and root planing were performed 1 week after the initial examination.

Results: No significant differences between the inorganic polyphosphate group and control were detected in each item except IL‐1β. Patients in whom both the bleeding on probing and gingival index at 1 week had improved were significantly older in the inorganic polyphosphate group than in the control group (p < 0.05). Bone regeneration was seen in one case of the inorganic polyphosphate group.

Conclusions: Inorganic polyphosphate was useful in the treatment of periodontitis in the elderly, indicating a probable effect of anti‐ageing, with similar bone regenerations occurring in both groups.
Factors associated with negative self‐perception of oral health among elderly people in a Brazilian community
Authors: Mesas Arthur Eumann , De Andrade Selma Maffei , Cabrera Marcos Aparecido Sarria
Published: February 2008

Objective:  Self‐perception of oral health is an important measurement for assessing the health and quality of life of elderly people. The aim of this study was to analyse associations between negative self‐perception of oral health and poor oral state, socio‐demographic variables, depression and use of medications.

Method:  In this cross‐sectional study, elderly people aged 60 to 74 years living in the urban zone of a city in southern Brazil were interviewed and examined. Functionally dependent individuals were excluded. Self‐perception was measured using the General Oral Health Assessment Index, and scores of 30 points or less were considered to represent negative perception. The physical, social and worry dimensions of this indicator were also analysed.

Results:  Two hundred and sixty‐seven elderly people (mean age 66.5 years, 59.9% female) were included in the study. Most of them had had little schooling. Negative self‐perception was identified in 18.7%, although none of the poor oral state was associated with this variable. In multivariate analysis, negative self‐perception was associated with female gender and depression. The women presented significantly lower means in the three dimensions analysed and individuals with depression, in the physical and social dimensions. Poor oral health (edentulism and absence of posterior occlusion) were associated with the physical dimension.

Conclusion:  Negative self‐perception of oral health was associated with gender and depression, but not with poor oral health. Therefore, gender and the presence of depression are factors to be taken into account in assessments involving this age group.
Evaluation of the clinical efficacy of a mouthwash and oral gel containing the antimicrobial proteins lactoperoxidase, lysozyme and lactoferrin in elderly patients with dry mouth – a pilot study
Authors: Gil‐Montoya Jose Antonio , Guardia‐López Inmaculada , González‐Moles Miguel Angel
Published: February 2008

Objectives:  To evaluate the clinical efficacy of a mouthwash and oral gel containing the antimicrobial proteins lactoperoxidase, lactoferrin and lysozyme, in a sample of elderly individuals with dry mouth.

Material and methods:  Twenty elderly institutionalised subjects with dry mouth and with a certain degree of independence for daily life activities were included in this pilot study. A randomised, double blind and cross‐over design was used. The study variables comprised subjective dry mouth sensation, the severity of discomfort assessed by means of a visual analogical scale (VAS), the Oral Health Impact Profile (OHIP), the presence of signs and symptoms of dry mouth, sialometry and Candida albicans culture. All the variables were recorded before and after each of the two periods of the study.

Results:  The 20 selected subjects we made up of 16 women and four men, with a mean age of 81.3 years. Improvement was observed on analysing the data between the first and second intervention period in terms of the OHIP values, the presence of dry mouth, and the need to drink fluids to swallow. However, the improvement in certain variables before and after treatment did not take a positive course in all cases, and some subjects even improved with placebo.

Conclusions:  The evaluated mouthwash and oral gel improved some subjective and clinical aspects in elderly individuals with dry mouth, though a placebo effect cannot be entirely discarded.
Watch This Space! Designing for Children's Play in Public Open Spaces
Authors: Woolley Helen
Published: February 2008

This article reviews one important aspect of children's environments in urban areas: play in public open spaces. The focus is on the provision of spaces for play for children aged between about 4–11 years old. The article argues that children's play is important for their development and for society as a whole and the article includes a short introduction to this, drawing on literature from a range of disciplines. The article then moves on to discuss aspects of the history of playgrounds during the 19th and 20th centuries, both in America and England. The article continues to draw on a range of literature while discussing play in public open spaces with respect to play value and need; design concepts and themes and design elements. The article concludes by contemplating whether the design of play in public open spaces will in the future draw more on the conclusions from academic literature than has happened during the last 40 years.
The Contours of Political Transformation and Conservation Areas in Southern Africa
Authors: Ramutsindela Maano
Published: February 2008

Ecology and other conservation sciences have largely been preoccupied with the establishment, number, size and the functions of nature conservation areas around the globe. Beyond these concerns, nature conservation areas mirror complex interrelationships between society and the environment, and how those relationships are, or should be managed in various contexts. These interrelationships cannot appropriately be understood within the confines of disciplinary boundaries; they require multi‐ and interdisciplinary perspectives. The aim of this article is to illustrate that various categories of nature conservation areas, including protected areas, embody ideas about nature and how it should be governed in changing socio‐economic conditions. The article draws on examples from southern Africa to argue that significant turns in strategies for protecting nature were made during periods of political transformation. It concludes that the gradation of protected areas, as a group of conservation areas, reflects different ways in which human activities are incorporated or marginalised in these areas. These processes are contingent on sociopolitical conditions.
Geographies of Environmental Governance: The Nexus of Nature and Neoliberalism
Authors: Himley Matthew
Published: February 2008

Environmental governance has emerged as both a key organizing concept and priority arena of research for nature–society geographers. This article offers a critical review of the burgeoning geographical literature on environmental governance, emphasizing how geographers have employed the concept to analyze how neoliberal globalization has entailed a fundamental reconfiguration of the organizational and institutional arrangements through which society–environment relations are governed. I begin by tracing the diverse bodies of scholarship and theoretical perspectives – including political ecology and institutional theories of political economy – that have shaped how geographers have approached environmental governance. I then examine three themes central to work on the ‘neoliberalization’ of environmental governance: privatization and enclosure, the rescaling of governance, and the role of oppositional social movements. Finally, I propose that future research place more emphasis on documenting and analyzing the practices of neoliberal environmental governance through ethnographic methods.
The Neglected Social Psychology of Institutional Racism
Authors: Berard Tim J.
Published: February 2008

Theories of institutional racism and institutionalized discrimination have been remarkably influential in the understanding of continuing racial inequality and contemporary race relations. These theories and related claims have also been criticized as being improperly conceptualized, employing circular reasoning, neglecting nonracial dimensions of inequality, failing to specify causal mechanisms, and employing questionable inferences and attributions. These issues can be illuminated by critically reviewing how theories of institutional racism and institutionalized discrimination handle issues of social psychology. Issues of social psychology are often treated only minimally or implicitly, and often dismissively. This neglect is the root of many concerns about theories of institutional racism and institutionalized discrimination. Increased attention to and employment of scholarship in social psychology can contribute greatly to an understanding of contemporary racial inequality and race relations that advances both academic interests and practical interests in the evaluation and reform of the institutional practices that perpetuate racial inequality.
Youth Transitions: Debates over the Social Context of Becoming an Adult
Authors: Pollock Gary
Published: February 2008

The study of young people has become a mainstay of social science. Education, employment, leisure, criminality, family life are all spheres within which the different experiences of young people have been examined. The principal tool for many of these studies has been a focus on transitions, looking at origins, journeys and destinations. The transition from school to work has been given the most attention, but increasingly there is interest in other life transitions such as (i) family development through relationships, marriage and children; and (ii) setting up a home outside that in which one was brought up. The focus on youth transitions has been found to be of use in both theoretical and policy developments. This paper reviews debates in the contemporary field of youth research and argues that only through taking a context‐specific transitional approach, focusing primarily on education and employment, can one fully understand and theorise the position of young people in society.
Rapid biodiversity assessment of spiders (Araneae) using semi‐quantitative sampling: a case study in a Mediterranean forest
Authors: CARDOSO PEDRO , SCHARFF NIKOLAJ , GASPAR CLARA , HENRIQUES SÉRGIO S. , CARVALHO RUI , CASTRO PEDRO H. , SCHMIDT JESPER B. , SILVA ISRAEL , SZÜTS TAMÁS , DE CASTRO ALBERTO , CRESPO LUIS C.
Published: February 2008

Abstract. 

A thorough inventory of a Mediterranean oak forest spider fauna carried out during 2 weeks is presented. It used a semi‐quantitative sampling protocol to collect comparable data in a rigorous, rapid and efficient way. Four hundred and eighty samples of one person‐hour of work each were collected, mostly inside a delimited 1‐ha plot.

Sampling yielded 10 808 adult spiders representing 204 species. The number of species present at the site was estimated using five different richness estimators (Chao1, Chao2, Jackknife1, Jackknife2 and Michaelis–Menten). The estimates ranged from 232 to 260. The most reliable estimates were provided by the Chao estimators and the least reliable was obtained with the Michaelis–Menten. However, the behavior of the Michaelis–Menten accumulation curves supports the use of this estimator as a stopping or reliability rule.

Nineteen per cent of the species were represented by a single specimen (singletons) and 12% by just two specimens (doubletons). The presence of locally rare species in this exhaustive inventory is discussed.

The effects of day, time of day, collector experience and sampling method on the number of adults, number of species and taxonomic composition of the samples are assessed. Sampling method is the single most important factor influencing the results and all methods generate unique species. Time of day is also important, in such way that each combination of method and time of day may be considered as a different method in itself. There are insignificant differences between the collectors in terms of species and number of adult spiders collected. Despite the high collecting effort, the species richness and abundance of spiders remained constant throughout the sampling period.
Longitudinal patterns of benthic invertebrates along a stream in the temperate forest in Japan: in relation to humans and tributaries
Authors: YOSHIMURA MAYUMI
Published: February 2008

Abstract. 

The relationship between benthic invertebrate assemblage composition and surrounding land use has been examined in various ways, but most studies are undertaken at a coarse scale, or they compare obviously different landscapes. In Japan, these obvious differences in landscape are rare, and humans reside even in remote montane areas.

In order to clarify the influence of human residence on benthic invertebrate assemblages, seasonal and site differences among benthic samples collected from a 15‐km stretch of Kuroson Stream and their relation with riparian land use were examined.

The number of individuals and genera differed significantly both spatially and temporally. Multivariate assemblage structure also differed significantly across space and time along the stream.

Increase of residential areas affected the in‐stream benthic invertebrate assemblage. Site differences along the stream and the effect of human residence were not masked by the potentially homogenizing influence of tributary streams.

The composition of surrounding vegetation was the most important factor influencing benthic community structure. The presence or absence of human residential areas and seasonal change were also important variables.

Benthic invertebrates may be carried and migrate to main streams from tributaries; however, this phenomenon was not observed. Assemblages of benthic invertebrates that inhabit a particular site do not change and are considered to vary seasonally across a certain range.
Efficient Ca2+ buffering in fast‐spiking basket cells of rat hippocampus
Authors: Aponte Yexica , Bischofberger Josef , Jonas Peter
Published: February 2008

Fast‐spiking parvalbumin‐expressing basket cells (BCs) represent a major type of inhibitory interneuron in the hippocampus. These cells inhibit principal cells in a temporally precise manner and are involved in the generation of network oscillations. Although BCs show a unique expression profile of Ca2+‐permeable receptors, Ca2+‐binding proteins and Ca2+‐dependent signalling molecules, physiological Ca2+ signalling in these interneurons has not been investigated. To study action potential (AP)‐induced dendritic Ca2+ influx and buffering, we combined whole‐cell patch‐clamp recordings with ratiometric Ca2+ imaging from the proximal apical dendrites of rigorously identified BCs in acute slices, using the high‐affinity Ca2+ indicator fura‐2 or the low‐affinity dye fura‐FF. Single APs evoked dendritic Ca2+ transients with small amplitude. Bursts of APs evoked Ca2+ transients with amplitudes that increased linearly with AP number. Analysis of Ca2+ transients under steady‐state conditions with different fura‐2 concentrations and during loading with 200 μm fura‐2 indicated that the endogenous Ca2+‐binding ratio was ∼200 (κS= 202 ± 26 for the loading experiments). The peak amplitude of the Ca2+ transients measured directly with 100 μm fura‐FF was 39 nm AP−1. At ∼23°C, the decay time constant of the Ca2+ transients was 390 ms, corresponding to an extrusion rate of ∼600 s−1. At 34°C, the decay time constant was 203 ms and the corresponding extrusion rate was ∼1100 s−1. At both temperatures, continuous theta‐burst activity with three to five APs per theta cycle, as occurs in vivo during exploration, led to a moderate increase in the global Ca2+ concentration that was proportional to AP number, whereas more intense stimulation was required to reach micromolar Ca2+ concentrations and to shift Ca2+ signalling into a non‐linear regime. In conclusion, dentate gyrus BCs show a high endogenous Ca2+‐binding ratio, a small AP‐induced dendritic Ca2+ influx, and a relatively slow Ca2+ extrusion. These specific buffering properties of BCs will sharpen the time course of local Ca2+ signals, while prolonging the decay of global Ca2+ signals.
A role for RGS10 in β‐adrenergic modulation of G‐protein‐activated K+ (GIRK) channel current in rat atrial myocytes
Authors: Bender Kirsten , Nasrollahzadeh Parastoo , Timpert Mathias , Liu Bing , Pott Lutz , Kienitz Marie‐Cécile
Published: February 2008

The effect of β‐adrenergic stimulation on endogenous G‐protein‐activated K+ (GIRK) current has been investigated in atrial myocytes from hearts of adult rats. β‐Adrenergic stimulation (10 μm isoprenaline, Iso) had no effect on activation kinetics, peak current or steady‐state current but resulted in slowing of deactivation upon washout of acetylcholine (ACh), the time constant (τd) being increased by a factor of about 2.5. The effect of Iso could be mimicked by inclusion of cAMP (500 μm) in the filling solution of the patch clamp pipette. The Iso‐induced increase in τd was blocked by the selective β1 receptor antagonist CGP‐20112A (2 μm) and by the PKA inhibitor H9 (100 μm included in the pipette solution). A candidate for mediating these effects is RGS10, one of the regulators of G‐protein signalling (RGS) species expressed in cardiac myocytes. Overexpression of RGS10 by adenoviral gene transfer resulted in a reduction in τd of 60%. Sensitivity of τd to Iso remained in cells overexpressing RGS10. Overexpression of RGS4 caused a comparable reduction in τd, which became insensitive to Iso. Expression of an RGS10 carrying a mutation (RGS10‐S168A), which deletes a PKA phosphorylation site, caused a decrease in τd comparable to overexpression of wild‐type RGS10. Sensitivity of τd to Iso was lost in RGS10‐S168A‐expressing myocytes. Silencing of RGS10 by means of adenovirus‐mediated transcription of a short hairpin RNA did not affect basal τd but removed sensitivity to Iso. These data suggest that endogenous RGS10 has GTPase‐activating protein (GAP) activity on the G‐protein species that mediates activation of atrial GIRK channels. Moreover, RGS10, via PKA‐dependent phosphorylation, enables a crosstalk between β‐adrenergic and muscarinic cholinergic signalling.
A glia–neuron alanine/ammonium shuttle is central to energy metabolism in bee retina
Authors: Coles Jonathan A. , Martiel Jean‐Louis , Laskowska Karolina
Published: February 2008

It has been proposed that glial cells may supply carbon fuel to neurons and also that there are fluxes of ammonium from neurons to glia. We have investigated both these proposals in Apis retinal slices, in which virtually all the mitochondria are in the photoreceptor neurons. Normally the superfusate contained no substrate of energy metabolism; addition of glucose or alanine did not increase oxygen consumption , confirming that the neurons received adequate substrate from glycogen in the glia. 1,4‐Dideoxy‐1,4‐imino‐d‐arabinitol (DAB, 100 μm), an inhibitor of glycogen phosphorylase, progressively decreased . This decrease was reversed by alanine but not glucose. Ammonium‐sensitive microelectrodes did not detect significant extracellular [NH4+] ([NH4+]e) in slices superfused with normal superfusate. Removal of Cl−, necessary for cotransport of NH4+ into the glia, increased [NH4+]e so that at the end of 2 min photostimulation mean [NH4+]e was 0.442 mm (s.e.m.= 0.082 mm, n= 16). In 0 Cl−, [NH4+]e was reduced by 2‐(methylamino)isobutyrate (MeAIB) an inhibitor of alanine transport. MeAIB also blocked oxidation of alanine in the presence of DAB, but did not decrease in normal superfusate. Lactate (l and d) and pyruvate (but not glucose) increased in DAB and decreased [NH4+]e in 0 Cl−. These results strengthen the evidence that in superfused retinal slices, glucose is metabolized exclusively in the glia, which supply alanine to the neurons, and that ammonium returns to the glia. They also show that another fuel (perhaps lactate) can be supplied by the glia to the neurons.
Glutamatergic transmission and plasticity between olfactory bulb mitral cells
Authors: Pimentel Diogo O. , Margrie Troy W.
Published: February 2008

In the olfactory bulb the sets of mitral cells that project their apical dendrite to the same glomerulus represent unique functional networks. While it is known that mitral cells release vesicular glutamate from their apical tuft it is believed that the resultant self‐excitation (SE), transmitted via dendritic gap junctions, is the main form of lateral transmission within the mitral cell assembly. In this study we used simultaneous whole‐cell recordings from mitral cell pairs to show that a direct form of chemical lateral excitation (LE) provides a means of mitral cell–mitral cell communication. In contrast to the ubiquitous expression and robust nature of SE, the efficacy of glutamatergic LE between mitral cells is highly variable and mediated by calcium‐impermeable AMPA receptors. We also find that the strength of LE is bi‐directionally modulated, in a homeostatic manner, by sniffing‐like patterns of presynaptic activity. Since these changes last many minutes we suggest that such mitral cell–mitral cell interactions provide the glomerular network with a locus for olfactory plasticity and a potential mechanism for receptive field modulation.
Ternary Kv4.2 channels recapitulate voltage‐dependent inactivation kinetics of A‐type K+ channels in cerebellar granule neurons
Authors: Amarillo Yimy , De Santiago‐Castillo Jose A. , Dougherty Kevin , Maffie Jonathon , Kwon Elaine , Covarrubias Manuel , Rudy Bernardo
Published: February 2008

Kv4 channels mediate most of the somatodendritic subthreshold operating A‐type current (ISA) in neurons. This current plays essential roles in the regulation of spike timing, repetitive firing, dendritic integration and plasticity. Neuronal Kv4 channels are thought to be ternary complexes of Kv4 pore‐forming subunits and two types of accessory proteins, Kv channel interacting proteins (KChIPs) and the dipeptidyl‐peptidase‐like proteins (DPPLs) DPPX (DPP6) and DPP10. In heterologous cells, ternary Kv4 channels exhibit inactivation that slows down with increasing depolarization. Here, we compared the voltage dependence of the inactivation rate of channels expressed in heterologous mammalian cells by Kv4.2 proteins with that of channels containing Kv4.2 and KChIP1, Kv4.2 and DPPX‐S, or Kv4.2, KChIP1 and DPPX‐S, and found that the relation between inactivation rate and membrane potential is distinct for these four conditions. Moreover, recordings from native neurons showed that the inactivation kinetics of the ISA in cerebellar granule neurons has voltage dependence that is remarkably similar to that of ternary Kv4 channels containing KChIP1 and DPPX‐S proteins in heterologous cells. The fact that this complex and unique behaviour (among A‐type K+ currents) is observed in both the native current and the current expressed in heterologous cells by the ternary complex containing Kv4, DPPX and KChIP proteins supports the hypothesis that somatically recorded native Kv4 channels in neurons include both types of accessory protein. Furthermore, quantitative global kinetic modelling showed that preferential closed‐state inactivation and a weakly voltage‐dependent opening step can explain the slowing of the inactivation rate with increasing depolarization. Therefore, it is likely that preferential closed‐state inactivation is the physiological mechanism that regulates the activity of both ternary Kv4 channel complexes and native ISA‐mediating channels.
Dissolution of extended defects in strained silicon
Authors: Moroz Victor , Martin-Bragado Ignacio , Felch Susan , Nouri Faran , Olsen Chris , Jones Kevin S.
Published: February 2008

The experimental and theoretical analyses performed in this work provide an insight into the impact of external stress on extended defects that form in silicon after ion implantation. It is shown experimentally that the embedded SiGe source/drain regions help to dissolve the extended defects in the adjacent silicon. The reduced amount of free and clustered interstitials is known to reduce junction leakage and increase dopant activation. These benefits are expected to improve further for the subsequent technology generations, due to the shrinking distance between the source and drain SiGe regions. A quantitative model of defect evolution in silicon with embedded SiGe is proposed. The model can be applied to optimize the combination of stress engineering, implant conditions, and thermal budget for the best device performance.
Simulation of doping profile formation: Historical evolution, and present strengths and weaknesses
Authors: Zechner C. , Moroz V.
Published: February 2008

Dopant profile simulation for silicon-based process technology is focused on ion implantation and thermal annealing. In this work, the evolution of present strengths and weaknesses of corresponding process simulation models is presented, together with an overview on current modeling improvements, driven by the progress in process technology and the increase of computational resources.
Probing doping conformality in fin shaped field effect transistor structures using resistors
Authors: Vandervorst W. , Jurczak M. , Everaert J.-L. , Pawlak B. J. , Duffy R. , Del-Agua-Bomiquel J.-I. , Poon T.
Published: February 2008

For scaling complementary metal oxide semiconductor devices toward the ITRS goals for the 32nm technology node and beyond, fin shaped field effect transistor (finFET)-based structures have shown immense potential due to their scalability by maintaining high drive current at scaled voltages and smaller gate dimensions. Due to the three-dimensional geometry of finFETs and the need to obtain identical lateral dopant profiles on the top and the sidewall of the fins, the classical doping strategies need to be reengineered as regular beam line implants would lead to large nonconformalities. The development of alternative doping processes such as plasma immersion doping requires the availability of methods to probe doping conformality. A methodology based on a dedicated resistor structure was developed, enabling the use of automated measurements to provide fast feedback on the degree of sidewall doping within different dies, across the wafer, and to study the wafer to wafer variation within a lot containing various splits. The methodology is validated by comparing the results with predictions based on a model describing the varying degree of conformality for beam line implants with different tilt angles.
Properties of ultralow energy boron implants using octadecaborane
Authors: Ameen M. S. , Rubin L. M. , Harris M. A. , Huynh C.
Published: February 2008

The material properties of junctions formed by implanting ultralow energy octadecaborane (B18H22+) followed by spike and flash annealings are reported. Along with providing significant drift mode beam current improvements at sub-1-keV energies, the B18H22 implants form an amorphous layer due to the large mass of the material. The authors have found that the thickness of the amorphous layer is dependent on the beam current of the implant, and that upon millisecond annealing, results in a shallow junction that is free of end-of-range damage. The authors have also investigated other issues critical to integrating B18H22 into standard complementary metal-oxide semiconductor processing. Dose retention and sputtering of silicon have been examined using secondary-ion-mass spectroscopy for implants ranging from 50eVto2keV. Of considerable concern is the ability to effectively strip photoresist from wafers without removing dopant that is placed within 1–2nm of the surface. The use of fluorine-free downstream ashing in combination with proper wet-cleaning techniques is shown to minimize undesirable dopant loss from the cleaning process.
Comparative study of size dependent four-point probe sheet resistance measurement on laser annealed ultra-shallow junctions
Authors: Petersen Dirch Hjorth , Lin Rong , Hansen Torben Mikael , Rosseel Erik , Vandervorst Wilfried , Markvardsen Christian , Kjær Daniel , Nielsen Peter Folmer
Published: February 2008

In this comparative study, the authors demonstrate the relationship∕correlation between macroscopic and microscopic four-point sheet resistance measurements on laser annealed ultra-shallow junctions (USJs). Microfabricated cantilever four-point probes with probe pitch ranging from 1.5to500μm have been used to characterize the sheet resistance uniformity of millisecond laser annealed USJs. They verify, both experimentally and theoretically, that the probe pitch of a four-point probe can strongly affect the measured sheet resistance. Such effect arises from the sensitivity (or “spot size”) of an in-line four-point probe. Their study shows the benefit of the spatial resolution of the micro four-point probe technique to characterize stitching effects resulting from the laser annealing process.
Defect evolution after germanium preamorphization in silicon on insulator structures
Authors: Fazzini P. F. , Cristiano F. , Dupré C. , Claverie A. , Ernst T. , Gavelle M.
Published: February 2008

Experimental data obtained in bulk and silicon on insulator (SOI) structures by transmission electron microscopy (TEM) are reported showing that the density of extended defects in SOI structures is reduced in comparison with bulk silicon. Additional data obtained on strained SOI structures show that a less pronounced reduction is observed in these structures. It will also be shown that simulations based on an already existing model and taking into account the effect of the Si/BOX interface acting as a sink for interstitials are not able to explain the experimentally observed defect density reduction in unstrained SOI.
Carrier concentration profiling on oxidized surfaces of Si device cross sections by resonant electron tunneling scanning probe spectroscopy
Authors: Bolotov L. , Nishizawa M. , Kanayama T. , Miura Y.
Published: February 2008

Quantitative carrier concentration profiles of super-junction power metal-oxide-semiconductor field-effect transistor devices were obtained by resonant electron tunneling (RET) scanning probe spectroscopy making use of a discrete energy level of adsorbed C60 molecules. RET voltage profiles measured on oxidized (100) surfaces of fine-polished cross sections revealed the presence of separated p-type islands in the n-type epitaxial layer and agreed well with the profiles obtained by local work function spectroscopy, although fluctuations were observed owing to surface defects and variations in the oxide and C60 film thickness. The derived boron concentration coincides with the implanted boron density obtained by numerical simulations. These results verify that the C60 RET scanning probe spectroscopy on oxidized surfaces has the ability of quantitative carrier concentration profiling of Si device cross sections, if flat surfaces with good quality are prepared.
Impact of the environmental conditions on the electrical characteristics of scanning spreading resistance microscopy
Authors: Eyben Pierre , Mody Jay , Vemula Sri Charan , Vandervorst Wilfried
Published: February 2008

Within this study, the authors have investigated scanning spreading resistance microscopy (SSRM) measurements on silicon samples under different environmental conditions. The authors have mainly focused on the possibility to reduce the required force for obtaining a stable electrical contact between the probe and the sample, and to improve the reproducibility of the technique by cleaving and measuring the samples in a controlled ambient. The authors demonstrate that, by measuring samples that were cleaved and maintained in nitrogen (N2) ambient, the force needed for a stable electrical contact between the probe and the sample was reduced by more than a factor of 3 when compared to the force required in air. This leads to an improved signal to noise ratio and enhanced reproducibility with remaining variations now below 10% for n-type as well as p-type samples. At the same time, tip requirements are relaxed and tip lifetime is improved. Our work has demonstrated that in situ SSRM is a very good candidate to fulfill the stringent ITRS requirements for two-dimensional carrier profiling.
Impact of band gap narrowing and surface recombination on photoelectrothermal modulated optical reflectance power curves
Authors: Dortu Fabian , Bogdanowicz Janusz , Clarysse Trudo , Vandervorst Wilfried
Published: February 2008

Photomodulated optical reflectance is a well established technique for surface and near surface characterizations. In this work, the nonlinear behavior of the differential reflectance as a function of the pump irradiance (104–106W∕cm2) is studied on uniformly and nonuniformly (p-n∕p+-p junctions) doped silicon structures, with a particular emphasis on the impact of band gap narrowing (BGN) and of surface recombination velocities (SRVs). We show that the BGN induced by the presence of excess carriers substantially influences the excess carrier profile. We also explain the unexpected shape of power curves on lowly doped substrate by a time-dependent variation of the SRVs during illumination.
Antimony for n-type metal oxide semiconductor ultrashallow junctions in strained Si: A superior dopant to arsenic?
Authors: Bennett N. S. , Smith A. J. , Gwilliam R. M. , Webb R. P. , Sealy B. J. , Cowern N. E. B. , O’Reilly L. , McNally P. J.
Published: February 2008

The creation of stable, highly conductive ultrashallow junctions in strained Si is a key requirement for future Si based devices. It is shown that in the presence of tensile strain, Sb becomes a strong contender to replace As as the dopant of choice due to advantages in junction depth, junction steepness, and crucially, sheet resistance. While 0.7% strain reduces resistance for both As and Sb, a result of enhanced electron mobility, the reduction is significantly larger for Sb due to an increase in donor activation. Differential Hall and secondary-ion mass spectroscopy measurements suggest this to be a consequence of a strain-induced Sb solubility enhancement following epitaxial regrowth, increasing Sb solubility in Si to levels approaching 1021cm−3. Advantages in junction depth, junction steepness, and dopant activation make Sb an interesting alternative to As for ultrashallow doping in strain-engineered complementary metal-oxide semiconductor devices.
Undercut structure fabricated by complementary-structure micropatterning technique for the passive-matrix display of organic light-emitting diodes
Authors: Xing Rubo , Xuan Yu , Ma Dongge , Han Yanchun
Published: February 2008

This paper reports a new patterning method, the complementary-structure micropatterning (CSMP) technique, to fabricate the undercut structures for the passive-matrix display of organic light-emitting diodes (OLEDs). First, the polyvinylpyrrolidone (PVP) stripe patterns with a trapeziform cross-section were formed by micromolding in capillaries. Then the photoresist was spin coated on the substrate with the patterned PVP stripes and developed in water. The PVP was dissolved and lifted off from the substrate with the photoresist deposited on it, resulting in the undercut structures of the remaining photoresist. The undercut structures with different configurations were obtained by adjusting the photoresist thickness. The undercut structures were further used as separators in the patterning of the passive-matrix display of OLEDs. No visible performance difference was observed compared with OLEDs patterned by the traditional method.
Fabrication and performance of nanoscale ultrasmooth programed defects for extreme ultraviolet lithography
Authors: Olynick D. L. , Salmassi F. , Liddle J. A. , Mirkarimi P. B. , Spiller E. , Baker S. L. , Robinson J.
Published: February 2008

The authors have developed processes for producing nanoscale programed substrate defects that have applications in areas such as thin film growth, extreme ultraviolet lithography, and defect inspection. Particle, line, pit, and scratch defects on the substrates between 40 and 140nm wide, 50–90nm high have been successfully produced using e-beam lithography and plasma etching in both silicon and hydrogensilsesquioxane films. These programed defect substrates have several advantages over those produced previously using gold nanoparticles or polystyrene latex spheres—most notably, the ability to precisely locate features and produce recessed as well as bump-type features in ultrasmooth films. These programed defects were used to develop techniques for planarization of film defects and results are discussed.
Nonlocal reduced boron diffusivity in silicon below strained Si1−xGex surfaces
Authors: Carroll Malcolm S. , Suh Y. S. , Levy R.
Published: February 2008

The silicon (Si) surface can be the dominant source of self-interstitials for many annealing conditions. Incorporation of germanium (Ge) and strain into the surface may be expected to perturb the equilibrium point defect concentrations at the surface (i.e., the atomic steps at which the point defects are generated and annihilated) and consequently in the bulk Si. In this work, boron (B) diffusion marker layers were epitaxially grown in Si by rapid thermal chemical vapor deposition followed by either undoped Si, 45nm of Si0.75Ge0.25, or 5nm of Si0.55Ge0.45 leaving a surface with three different Ge contents. The B diffusivity (DB) below the Si1−xGex surface layers was found to be as much as two times slower than that in the all-Si samples between 800 and 900°C. The activation energy for the DB in the Si1−xGex capped samples was also observed to increase to ∼4.1eV. This work demonstrates that a Si1−xGex surface can reduce the DB in the underlying Si during N2 annealing. Furthermore, this novel test structure helps separate the effects of strain and local Ge trapping on DB in Si1−xGex.
Grayscale lithography by a polymer photomask doped with laser dye
Authors: Korivi N. S. , Zhou Y. X. , Jiang L.
Published: February 2008

This article reports on the development of a novel grayscale photomask which operates on the basis of differential absorption of ultraviolet (UV) light in photoabsorbing material. The developed photomask is made of a patterned, moldable polymer (polydimethylsiloxane) doped with a laser dye (Coumarin 314). The doped polymer functions as photoabsorbing material. Due to the moldable nature of polydimethylsiloxane, micro- and nanostructures can be created on its surface from a complementary mold relief. By adjusting the thickness of patterns formed on the photomask, concentration of the dye in the polymer, and UV exposure dose, a multitude of unique multidimensional microstructures can be fabricated with desired geometries and dimensions. Using the developed polymer photomask with a standard UV source, three-dimensional microstructures with different heights have been formed in positive photoresist by a single UV exposure step. This method is inexpensive compared to other grayscale lithography techniques and relatively easy to implement due to its process simplicity.
Recent advance in protection technology for extreme ultraviolet lithography masks under low-pressure condition
Authors: Kim Jung Hyeun
Published: February 2008

Extreme ultraviolet lithography (EUVL) is considered a leading lithography technology for the next generation of semiconductor devices. Various noncontact approaches for protection of the EUVL masks from particle contamination have to be used due to the lack of any usable common membrane pellicles during all handling steps. In this article, protection schemes for EUVL masks from nanoparticle contamination are given and proper experimental verifications are followed. The experimental investigations for the proposed protection schemes are examined with (i) maintaining the critical surfaces upside down to avoid gravitational settling of particles onto the mask; (ii) use of a cover plate to reduce the volume from where particles might reach the surface; (iii) application of a thermal and/or electrical gradient to expose particles to a repelling thermophoretic and/or electrophoretic force. The proposed schemes showed excellent effects on protection of critical surfaces under low-pressure condition.
Flare-variation compensation for 32nm line and space pattern for device manufacturing on extreme-ultraviolet lithography
Authors: Aoyama H. , Iriki N. , Tanaka T.
Published: February 2008

One of the critical issues in extreme-ultraviolet lithography (EUVL) is flare, which degrades the contrast of aerial images and control of the critical dimension (CD) across the exposure field and is related to the density of the absorber layout. It is necessary, therefore, to determine a process window under flare-variation compensation (FVC), taking into account residual FVC error and estimated resist properties. In this article, the authors specify a process window for 32nm line/space patterns under a FVC framework based on rigorous aerial-image simulations. FVC, by means of proper mask resizing, can provide an exposure latitude of up to 23% or more. A 0.5nm grid can be used for mask-data preparation due to the low mask-enhancement error factor of EUVL. In addition, resist blur, estimated by convolving a Gaussian function to aerial images, has a significant impact and the standard deviation of the blur needs to the kept below 7nm to obtain a usable process window, considering mask CD error and the process margin for flare levels of 0%–10%.
Atomic diffusion and interface electronic structure at In0.49Ga0.51P∕GaAs heterojunctions
Authors: Smith P. E. , Lueck M. , Ringel S. A. , Brillson L. J.
Published: February 2008

We have performed cross-sectional cathodoluminescence spectroscopy and secondary ion mass spectrometry measurements of lattice-matched, SiOx-capped In0.49Ga0.51P∕GaAs double heterostructures (DHs) in order to investigate the relation between chemical interactions and localized electronic states at the epitaxial heterojunction. We measure atomic diffusion of over 100nm resulting from anneals ranging from 650to850°C. A 20meV increase in the near-band-edge (NBE) emission energy of InGaP is observed after the highest temperature anneals. This increase is consistent with an increase in the Ga concentration of the ternary layer as a result of diffusion from neighboring GaAs layers. Additionally, we observe InGaP∕GaAs interface-localized features at ∼1.49 and ∼1.37eV. The intensity of these emissions relative to the band-edge emission of the underlying layer depends sensitively on the anneal temperature and corresponding diffusion. These results reveal a correlation between cross diffusion and defect emission at InGaP∕GaAs interfaces. They clarify the nature of the cross diffusion and reactions that occur at these interfaces in SiOx-capped structures, and those may be expected to occur during interface growth or processing at elevated temperatures. It is demonstrated that these chemical effects can have a significant impact on the electronic structure of lattice-matched III-V heterostructures.
Electrical conductivity of ultra-thin silicon nanowires
Authors: Rochdi Nabil , Tonneau Didier , Jandard Franck , Dallaporta Hervé , Safarov Viatcheslav , Gautier Jacques
Published: February 2008

The authors present results on fabricating ultra-thin silicon nanowires on insulators and characterizing their electrical conductivity. The silicon nanowires were fabricated by atomic force microscopy lithography on ultra-thin (8 nm) silicon on insulator substrates. At such minute thicknesses, the device exhibits high sensitivity to the charges trapped at the Si/SiO2 interface. This leads to an unusual behavior of the electrical conductivity of the nanowires as a function of drain-source and gate voltages.
Level set modeling of the orientation dependence of solid phase epitaxial regrowth
Authors: Morarka Saurabh , Rudawski N. G. , Law Mark E.
Published: February 2008

Level set methods have previously been successfully implemented in interface propagation for etching and deposition processes. In this article, the authors show that level set methods can be used to model solid phase epitaxial regrowth. The model incorporates orientation dependence of regrowth as found by Csepregi et al. [J. Appl. Phys. 49, 3906 (1978)]. The orientation dependent velocity data are taken from Csepregi’s paper and fitted to a polynomial function to give the growth velocity for level set methods. Simulations show the capability of our model in predicting the pinching of the corners in ⟨111⟩ direction and humplike shape in ⟨100⟩ direction. This is confirmed by the transmission electron microscope pictures from recent papers. This modeling holds special interest because of the different diffusivities of boron in amorphous and crystalline silicon (approximately five orders of magnitude difference) and because of the various defects forming at the pinching corners which could lead to higher leakage current in scaled devices. The level set model is implemented in FLOOPS.
Facet formation and lateral overgrowth of selective Ge epitaxy on SiO2-patterned Si(001) substrates
Authors: Park Ji-Soo , Bai Jie , Curtin Michael , Carroll Mark , Lochtefeld Anthony
Published: February 2008

Faceting and lateral overgrowth have been investigated for Ge selectively grown on Si(001) substrates in trench regions bound by SiO2 sidewalls. In wet-etched large trenches with sloped sidewalls, Ge faceting behavior was similar to Si and SixGe1−x faceting: slow-growing {113} facets dominate, with {111} facets expanding as the layer became thicker. However, the {111} facet length for Ge was much smaller than that of Si; this can be explained in terms of mass transport and accumulation, as well as energy minimization and the higher surface diffusivity of Ge. In dry-etched small trenches with vertical sidewalls, minimization of the high-energy interface area between Ge and SiO2 appears to be most critical in determining faceting morphology. Overgrowth of Ge led to void formation at the oxide interface, presumably to avoid the high-energy Ge/SiO2 interface. Upon coalescence of lateral-growth regions, fast-growing (001) forms and dominates subsequent growth. Thus, the total thickness of the overgrown Ge layer was closely related to the width of the SiO2 region between trenches.