bluuebunny/crossref_metadata_2025 huggingface dataset:
The timing of magmatism, uplift and crustal extension: preliminary observations from Yemen
Authors: Menzies M. A. , Baker J. , Bosence D. , Dart C. , Davison I. , Hurford A. , Al’Kadasi M. , McClay K. , Nichols G. , Al’Subbary A. , Yelland A.
Published: September 2007

The Red Sea and the Gulf of Aden form young, oceanic rift basins, situated between the diverging African and Arabian plates and bordered by highly elevated, volcanic margins. Yemen in the southeastern Red Sea, was once centred over the Afar plume/triple-junction (
c.
30 Ma) forming part of the Arabian ‘passive’ margin. The present high elevation of the Afro-Arabian rift-flanks (up to 3.6 km as in Yemen), is the combined result of a number of endogenic rift processes which served to generate both the initial crustal uplift and also preserve the elevated topography. A further isostatic response generating uplift is likely to have been driven by differential erosion of the rift-flanks. However, the sedimentary record of the pre-Jurassic to early Tertiary period provides little evidence for major changes in relief or elevation. Furthermore, structural and volcanological observations indicate that most of the crustal extension occurred during mid-late Tertiary. The voluminous Oligo-Miocene basalt-rhyolite magmatism of Yemen was not apparently associated with pre-volcanic (> 30 Ma) uplift despite the commonly held belief that the Afar plume existed beneath the region 30 Ma ago. Geological data point to an episode of uplift that occurred after the initiation of magmatism. Fission track data indicate that uplift related exhumation postdates magmatism by some 10–15 Ma, perhaps the amount of time needed to change the thermal character of the Pan-African lithosphere above the Afar plume. A sequence of magmatism followed by synchronous crustal extension and uplift for Yemen does not fit with the traditional categories of active (uplift-magmatism-rifting) and passive (rifting-uplift-magmatism) rifting. Clearly such end-member models do not simply apply to the Red Sea or the Great Basin of the western USA where a period of tectonic quiescence, followed by post-volcanic extension and uplift (1 km), post-dated the Oligo-Miocene ignimbrite flare-up.
Tectonism and magmatism during NE Atlantic continental break-up: the Vøring Margin
Authors: Skogseid Jakob , Pedersen Tom , Eldholm Olav , Larsen Bjørn T.
Published: September 2007

The temporal and spatial relationships of tectonic and magmatic features on the Vøring volcanic margin show that continental break-up occurred in association with significant magmatic activity about 18 Ma after initiation of lithospheric extension. From the distribution of extension across the margin and the volumes of melt produced, a thermal anomaly of 50–80°C is estimated, in agreement with predictions from recent plume models. A tectono-magmatic model is proposed in which the ascending proto-Iceland plume released the rifting, over a > 300 km wide zone, by uplift-induced extension of the NE Atlantic lithosphere already affected by tensional stresses. Initial rifting took place without decompressional melting when the plume, carrying the thermal anomaly, was still 600–700 km beneath the lithosphere. Subsequently, widespread magmatism occurred when the plume impinged on, spread out beneath and infilled the rift-defined relief at the base of the lithosphere. Break-up is suggested to be a consequence of melt-induced weakening of the lithosphere, whereas the anomalously thick igneous crust at the continent-ocean transition along the NE Atlantic margins is explained by melt focusing towards the uplifted break-up axis.
Tertiary picrites in West Greenland: melting at the periphery of a plume?
Authors: Gill R. C. O. , Pedersen A. K. , Larsen J. G.
Published: September 2007

The West Greenland/Baffin Island Tertiary volcanic province differs from other CFB provinces in containing an unusually high proportion (30–50% by volume) of magnesian picritic lavas and hyaloclastites. Olivine-liquid equilibrium considerations suggest the presence during the earlier stages of eruption of picritic melts with MgO contents as high as 20%. Calculations based on McKenzie-Bickle melting models point to high degrees of melting (24–30%) at depths of 60–90 km in the underlying mantle, and require potential temperatures of 1540–1600°C. Such high potential temperatures are inconsistent with reconstructions that attribute the West Greenland volcanism to melting on the margins of the incipient Iceland plume-head. The distribution of Tertiary volcanic activity in Greenland, in particular its relation to Mesozoic-Tertiary extensional basins, indicates that lithospheric structure plays a part in determining where the plume-head can undergo melting. But to explain the restriction of high-temperature picrites to West Greenland, together with their distinctive trace element geochemistry, it is necessary to invoke (a) either an elongated Icelandic plume initially extending as far as West Greenland or a short-lived precursory plume head that developed directly beneath West Greenland, and (b) an active extensional regime that allowed rapid access of picritic melts to the surface.
Sill-intrusion, flood basalt emplacement and deep crustal structure of the Scoresby Sund region, East Greenland
Authors: Larsen H. C. , Marcussen C.
Published: September 2007

The late Palaeozoic-Mesozoic Jameson Land basin in East Greenland was situated during early Tertiary break-up 300–400 km north of a presumed plume centre and 100–200 km landward of the initial line of North East Atlantic opening. The basin continues southward below Scoresby Sund fiord and the Scoresby Sund plateau basalts south of the fiord. By combining surface mapping with marine reflection and refraction seismics from Scoresby Sund and deep (6–12s) reflection seismics from the exposed part of the basin, it is possible to construct a composite image of the entire crustal structure in this region from the details of basalt stratigraphy at the top, through the basin fill, the foundation of the basin, and into the uppermost mantle. At the basin centre there is a very thin crystalline crust (6–8 km?) below as much as 16–18 km of basin fill. Virtually all crustal extension took place prior to mid-Permian time, and the post-rift Upper Permian to Cretaceous section contributes to only one third or less of the total thickness of the succession. During Tertiary break-up the basin was intruded by basaltic sills and dykes, and basaltic flood basalts flowed over the basin with an apparently decreasing thickness to the north. The sills are mainly exposed along the basin margins as rather thin (10–15 m) layers, but apparently increase in intensity and thickness at depth and towards the basin centre. It seems that magmas were intruded as sills up to 300 m thick in the deep (10–15 km) central parts of the basin, from where they ascended towards the basin margins and to much younger stratigraphic levels. Their geometry and possible volume make them potential candidates as mid-crustal magma chambers and crustal magma pathways for the flood basalts which show low-pressure fractionation. However, extension surface geological data and deep crustal reflection seismic data show no faulting or crustal extension associated with this intense break-up volcanism. In Scoresby Sund there is a general rather conformable relationship between the basin stratigraphy and the gross stratigraphy of the flood basalts, suggesting limited or no initial uplift prior to flood basalt volcanism. The present-day high elevation of the basalts is considered part of large regional margin uplift post-dating N Atlantic break-up by 20 Ma or more. The apparent guidance exerted by the basin on the break-up magmatic activity without renewed rifting of the basin itself, the apparent lack of a broad initial uplift during break-up, and the late regional margin uplift, all seem at odds with several current plume models.
Changes in moisture balance between glacial and interglacial conditions: influence on carbon cycle processes
Authors: Adams J. M. , Faure H.
Published: September 2007

During the arid Late Glacial and Last Glacial Maximum (between approximately 30 000 and 13 000 calendar years ago), vegetation cover retreated and large areas of the continents were occupied by desert and semi-desert vegetation. The result of this general decrease in biological activity would have been a decrease in the size of the land carbon reservoir, and a decrease in the rate of chemical rock weathering. By contrast, during the early-mid-Holocene, conditions in many areas seem to have been moister than today due to a more active hydrological cycle. All of these processes would have affected the global carbon cycle and altered the amplitude and timing of the climate fluctuations themselves. In effect, the climatic shift between glacial and interglacial conditions creates a very large ‘missing source’ of carbon, perhaps amounting to thousands of gigatonnes, to account for the carbon uptake by the land system during the present interglacial, and thus carbon cycle models of the late Quaternary may need to be revised extensively.
Human dimensions of palaeohydrological change
Authors: Brown A. G.
Published: September 2007

Because floodplains are ‘attractors’ of human activities and settlement, Late Pleistocene and Holocene palaeohydrological changes are an important part of archaeology. Indeed there has been a tradition of palaeohydrological writing within archaeology centring around topics such as river transport, drought/floods and floodplain farming, rivers as physical and cultural barriers, riverine resources, and the flood hazard. An agenda for continuing research in this inter-disciplinary area in a more quantitative and rigorous manner than in the past has been developed. This recognizes that the potential of palaeohydrological research to be applied to the study of past and future environmental change revolves around three areas: (i) the estimation of past frequency distributions and their relationships to climate; (ii) the past and future representations of risks; such as flooding; (iii) the uses and limitations of analogies (e.g. by using the Medieval climatic optimum as an analogy for future global warming).
Climatic or anthropogenic alluviation in Central European valleys during the Holocene?
Authors: Kalicki T.
Published: September 2007

Traces of increased river activity during the Late Glacial and Holocene can be identified in the river valleys of central Europe. This activity includes changes of river channel pattern and changes in the type and rate of floodplain sedimentation. A model of the sequence of events within a phase of increased river activity has been constructed as part of a detailed study of the Vistula valley. This analysis indicated that the evolution of the Vistula river valley has resulted primarily from climatic factors, although local factors (including human modification) contributed to the magnitude of changes which had already developed as a result of climatic controls.
Issues in scientific co-operation on information sharing: the case of palaeohydrology
Authors: Branson J. , Gregory K. J. , Clark M. J.
Published: September 2007

The hydrological cycle is interactively integral with climate, so that for an understanding of future environmental change it is important to have hydrological data accessible from previous times to use in both hydrological and climate change modelling of past, and also of present and future environments and also for the development and operation of surface water resources. A database has been developed as part of the research undertaken by the INQUA Global Continental Palaeohydrology Project (GLOCOPH) to facilitate the preservation and access of palaeohydrological data within the public domain, and through this the organization, facilitation, association and bisociation of the data.
Deviation from Red Queen behaviour at stratigraphic boundaries: evidence for directional recovery
Authors: Doran N. A. , Arnold A. J. , Parker W. C. , Huffer F. W.
Published: September 2007

Boundary-defining events influence the evolutionary behaviour of post-extinction survivors. The Cox proportional hazards model takes into account the varying background extinction rates characteristic of boundaries and enables survivorship analysis of post-boundary behaviour. Survivorship results from the Middle Cretaceous to recent planktonic foraminifera reveal two intriguing observations. First, they indicate significantly age-dependent extinction probabilities in populations of species following two boundaries: Cenomanian-Turonian (C-T) and Cretaceous-Tertiary (K-T); the survivors are short lived and show rapid turnover. Characteristics that might mediate this macroevolutionary behaviour are clearly distinct from those that precede the extinction. We hypothesize that the rapid taxonomic turnover during post-extinction macroevolutionary recovery is driven by the lingering expression of ‘passport’ characteristics, where the primary adaptive value was during the preceding extinction. Second, age-dependency of extinction oscillates through time. Many survivorship curves averaging long-term data have exponential or near-exponential form: suggesting a lack of age-dependence consistent with the Red Queen hypothesis. The boundary events discussed here, analysed in higher-resolution 15 Ma subsets, demonstrate perturbation of some post-extinction populations toward positive age-dependence, and are followed by long intervals suggestive of recovery. Red Queen behaviour, when measured over very long time-spans, appears to be the time-averaged result of these boundary-generated oscillations between short-term positive age-dependence and longer-term return to nearly age-independent Red Queen behaviour.
Palynostratigraphy of the Upper Carboniferous Langesttian-Duckmantian Stage Boundary in Britain
Authors: Mclean Duncan , Owens Bernard , Bodman David
Published: September 2007

A critique of palynostratigraphic zonation schemes associated with the Langsettian-Duckmantian Stage boundary shows that, at high levels of stratigraphic resolution, most criteria used as palynological proxies for the position of the boundary are unsuitable. Most importantly, in the Duckmantian stratotype section the highest stratigraphic occurrence of the index species
Schulzospora rara
is above (rather than below or within) the Vanderbeckei Marine Band, the base of which defines the Duckmantian Stage. A cored section through the boundary in southern North Sea well 44/22-1 displays comparable microfloral distributions. While data are as yet too sparse to provide detailed answers, the findings have implications for understanding how marine flooding events affected Carboniferous microfloral evolution and extinction. Ultimately this influences how microfloral biozone boundaries relate to the regional European Upper Carboniferous stage boundaries, which are largely defined in relation to strata deposited during marine flooding events similar to that associated with the Langsettian-Duckmantian boundary. The miospore genus
Sinuspores
Artüz is emended, and two new taxa are described:
Gondisporites bulboides
sp. nov. and
Hymenospora murdochensis
sp. nov.
Response of tropical African and East Atlantic climates to orbital forcing over the last 1.7 Ma
Authors: Jahn B. , Schneider R. R. , Müller P.-J. , Donner B. , Röhl U.
Published: September 2007

Records of organic matter accumulation, organic carbon isotopic composition and iron content covering the last 1.7 Ma are presented for the Congo Fan Ocean Drilling Program (ODP) Site 1075, and are compared with their counterparts from ODP Site 663 in the equatorial upwelling region. They are discussed with regard to variations in African precipitation and Congo River discharge and in the context of changes in trade-wind-driven marine productivity for the tropical Atlantic at periodicities typical of Milankovitch forcing. On the Congo Fan, elevated total organic carbon mass accumulation rates (TOC MAR) and Fe intensities occur predominantly during interglacial periods when the African monsoon was most intense. Band-pass filtering applied to TOC MAR shows distinct precessional variations, indicating that the African climate was largely controlled by low-latitude insolation changes. Only for the last 0.6 Ma, an interval of enhanced glacial-interglacial climate changes, is the precessional TOC MAR signal superimposed by a strong 100 ka oscillation. In contrast, variations in terrestrial iron input to the Congo Fan indicate pronounced 100 ka variance already well before global glacial-interglacial cycles increased in amplitude between 0.9 and 0.6 Ma. Obliquity cycles in the Fe signal are strongly expressed for the last 0.9 Ma. The highest amplitudes in the precessional variance of fluvial Fe input occur when amplitudes in the 100 ka oscillation were at intermediate levels and reveal a 800 ka cycle in phase shift with respect to precessional forcing. Together with a pronounced 800 ka signal in the 100 ka amplitude variations during the last 1.7 Ma, the Congo Fan iron record therefore suggests that eccentricity modulation of the low-latitude insolation directly influenced the equatorial African monsoon system and probably the weathering conditions on land. It further suggests that low-latitude precessional forcing and monsoonal response in the tropics might have played an important role for 100 ka cycles in global climate well before huge continental ice sheets existed.
Deep-sea benthic foraminiferal record of the mid-Pleistocene transition in the SW Pacific
Authors: Hayward Bruce W. , Grenfell Hugh R. , Sabaa Ashwaq T. , Sikes Elizabeth
Published: September 2007

Benthic foraminiferal faunas from three bathyal sequences provide a proxy record of oceanographic changes through the mid-Pleistocene transition (MPT) on either side of the Subtropical Front (STF), east of New Zealand. Canonical correspondence analyses show that factors related to water depth, latitude and climate cycles were more significant than oceanographic factors in determining changes in faunal assemblage composition over the last 1 Ma. Even so, mid-Pleistocene faunal changes are recognizable and can be linked to inferred palaeoceanographic causes.

North of the largely stationary STF the faunas were less variable than to the south, perhaps reflecting the less extreme glacial-interglacial fluctuations in the overlying Subtropical Surface Water. Prior to Marine Isotope Stage (MIS) 21 and after MIS 15, the northern faunas had fairly constant composition, but during most of the MPT faunal composition fluctuated in response to climate-related food-supply variations. Faunal changes through the MPT suggest increasing food supply and decreasing dissolved bottom oxygen.

South of the STF, beneath Subantarctic Surface Water, mid-Pleistocene faunas exhibited strong glacial-interglacial fluctuations, inferred to be due to higher interglacial nutrient supply and lower oxygen levels. The most dramatic faunal change in the south occurred at the end of the MPT (MIS 15–12), with an acme of
Abditodentrix pseudothalmanni
, possibly reflecting higher carbon flux and lowered bottom oxygen.

This study suggests that the mid-Pleistocene decline and extinction of a group of elongate, cylindrical deep-sea foraminifera may have been related to decreased bottom oxygen concentrations as a result of slower deep-water currents.
Distribution of the calcareous nannofossil
Reticulofenestra asanoi
within the Early-Middle Pleistocene transition in the Mediterranean Sea and Atlantic Ocean: correlation with magneto- and oxygen isotope stratigraphy
Authors: Reale Viviana , Monechi Simonetta
Published: September 2007

Quantitative analyses of the calcareous nannofossil
Reticulofenestra asanoi
and related species have been performed on the Early-Middle Pleistocene transition in the Mediterranean Sea (ODP Sites 976 and 963) and Atlantic Ocean (DSDP Hole 610A) in order to improve the understanding of their stratigraphic distributions. Abundance patterns have allowed the identification of the lowest common occurrence (LCO) and highest common occurrence (HCO) of
R. asanoi
in a short interval below and above the lowest occurrence of
Gephyrocapsa
sp. 3. Correlation with oxygen isotope stratigraphy at Site 976 places the LCO of
R. asanoi
at the Marine Isotope Stage (MIS) 34-33 transition and its HCO at the MIS 23-22 transition. At Site 963, the HCO of
R. asanoi
(estimated age of 0.96 Ma correlated to MIS 25) is regarded as ‘artificially’ low, and its highest occurrence (estimated age 0.90 Ma correlated to MIS 23) has therefore been used for bio-chronostratigraphic correlation. The LCO of
R. asanoi
is estimated at 1.05 Ma at Site 963 and 1.17 Ma at Hole 610A, which suggests correlation to MIS 30 and MIS 35, respectively. These data suggest a possible diachrony for the LCO of
R. asanoi
.
Pollen records and climatic cycles in the North Mediterranean region since 2.7 Ma
Authors: Suc Jean-Pierre , Popescu Speranta-Maria
Published: September 2007

This synthesis incorporates the 16 most important pollen records available across the North Mediterranean region
sensu lato
for the last 2.7 Ma. Their location is discussed with respect to the present-day bioclimatic Mediterranean realm. A special effort has been made to redraw, where necessary, the pollen records in terms of modern cyclostratigraphy. The complexity of the evolution of the Mediterranean flora and vegetation as forced by the climatic cycles is evident. The influence of the latitudinal thermic (and xeric) gradient is confirmed, and the superimposition of a longitudinal gradient, forced by the Asian monsoon, is considered. The Mediterranean flora and vegetation were not altered by any important event during the Early-Middle Pleistocene transition between 1.2 and 0.7 Ma.
Climatic patterns revealed by pollen and oxygen isotope records across the Matuyama-Brunhes Boundary in the central Mediterranean (southern Italy)
Authors: Capraro L. , Asioli A. , Backman J. , Bertoldi R. , Channell J. E. T. , Massari F. , Rio D.
Published: September 2007

A
c.
50 m thick section located in the Crotone Basin (southern Italy) was investigated using oxygen isotopes, pollen and planktonic foraminifera. The section records two complete transgressive-regressive cycles mainly driven by glacio-eustasy. Biostratigraphy and oxygen isotope chronology indicate that the section spans from Marine Isotope Stage (MIS) 22 (
c.
0.87 Ma) to MIS 18.3 (
c.
0.73 Ma), thus straddling the Matuyama-Brunhes (M-B) boundary which occurs in the middle of MIS 19. The rich pollen assemblages provide a unique record of the vegetation in the central Mediterranean during the Early-Middle Pleistocene climatic transition. Interglacials are characterized by a mesothermic vegetation similar to the present day, whereas a rain-demanding conifer forest dominates the glacials of MIS 20 and MIS 18. This is unexpected because it is generally considered that during the Pleistocene, glacials in central Mediterranean were characterized by steppe (arid) conditions. By contrast, arid conditions occur during the deglaciations. These results are inconsistent with the widespread practice of linking glacials with arid conditions in the central Mediterranean during Pliocene and Early Pleistocene times. This study emphasizes the need to establish more accurate land-sea correlation.
Early-Middle Pleistocene structural changes in mammalian communities from the Italian peninsula
Authors: Palombo Maria R. , Raia Pasquale , Giovinazzo Caterina
Published: September 2007

The late Early and Middle Pleistocene mammal fossil record of Italy has been revised by grouping faunal lists into discrete faunal complexes, termed cluster units, by means of bootstrapped cluster analysis which allows the evaluation of group partition sharpness. These complexes have been compared with previously erected Italian biochrons and then analysed for their body size (by cenogram analysis) and diversity trends. Some considerations about changes in predator-prey ratios are made. It is shown that diversity increased sharply at the onset of the middle Galerian mammal age, coincident with the well-known shift from 40 to 100 ka glacial-interglacial periodicity. This increased diversity was entirely driven by the concurrent arrival in Italy of some large ungulates. Cenograms reveal that the climate became wetter and markedly cooler following the arid conditions that characterize the late Early Pleistocene. Wetter environments are generally expected to sustain a higher proportion of large herbivore species. Because carnivore species did not respond in the same way, the predator-prey ratio changed in favour of prey. In summary, the transition from Early to Middle Pleistocene faunas (from early to middle Galerian mammal ages) represents a major reorganization in the large-mammal complexes from the Italian peninsula. This was reflected in both the diversity and trophic structure of large-mammal communities.
Hominins and the Early-Middle Pleistocene transition: evolution, culture and climate in Africa and Europe
Authors: McNabb John
Published: September 2007

Some of the more important evidence is reviewed for the archaeology of hominin colonization associated with the Early-Middle Pleistocene transition. This is done by reference to the nature of migration ‘out of Africa’ before the interval of transition, across the transition itself, and then after it. Technologically assisted behaviour may not have been so important in the colonization process, behaviour and biology being the primary factors that led to the success of a migrating species. While climate change and especially shifts in local aridity would have been experienced and possibly remembered by localized hominin groups, the Acheulean behavioural repertoire did not change much across Africa and Europe over a million years of time. It merely adapted to local conditions. The Acheulean was a generalized hand-held processing technology for a generalized hominin.
A Bicycle Made for Two? The Integration of Scientific Techniques into Archaeological Interpretation
Authors: Pollard A. Mark , Bray Peter
Published: September 2007

Much of the literature on the integration of science and archaeology has tended to focus on mistakes, tensions, and problems. Many scholars have also been obsessed with definitions and delineating the boundaries between varieties of archaeologist. In this article we aim to move away from this by discussing the pragmatic ways that progress has been achieved in applying scientific solutions to interpreting the past. Progress has not been dependent on overcoming supposed fundamental differences between the humanities and sciences; instead it has been based around cooperation on the vast tracts of common ground. This article highlights key arenas that encourage this process of information flow and discussion: interdisciplinary field work, new scientific techniques, new archaeological questions, and education. What is increasingly important in archaeology is how we can encourage researchers to contribute to group solutions of problems and cross outdated disciplinary boundaries.
Semiotic Anthropology
Authors: Mertz Elizabeth
Published: September 2007

From the 1970s through the present, semiotic anthropology has grown in importance but also has shifted its emphasis, in the process helping to push forward a more general change in the subfields of linguistic and sociocultural anthropology. This article explores that change from the vantage of each of these key subfields, arguing that core concepts of semiotic anthropology have permitted a new rapprochement between sociocultural and linguistic analyses—one which permits each to make better use of the insights of the other. It has also aided anthropologists in overcoming stale conceptual oppositions. Five specific points of contact are explored: (a) indexicality and social context; (b) metalinguistic structuring/linguistic ideology, pragmatics, and social interaction; (c) social power, history, and linguistic interaction; (d) agency, linguistic creativity, and “real time”; and (e) shifting sites, units of analysis, and methods.
In-Line Characterization of Heterojunction Bipolar Transistor Base Layers by High-Resolution X-Ray Diffraction
Authors: Nguyen Ngoc Duy , Loo Roger , Hikavyy Andriy , Van Daele Benny , Ryan Paul , Wormington Matthew , Hopkins John
Published: September 2007

The suitability of high-resolution X-ray diffraction (HRXRD) as an in-line measurement tool for the characterization of heterojunction bipolar transistor SiGe base layers and Si cap layers was investigated. We showed that despite of polycrystalline Si on the mask material of patterned wafers, HRXRD measurements performed on an array of small windows yield results which are comparable to those that were obtained on a window which is larger than the size of the source beam, regarding the thickness and the Ge content of the SiGe layers. The possibility to extract layer parameters for active device windows of different sizes was therefore demonstrated. The suitability of HRXRD for in-line measurement of the Si cap thickness was also assessed and the sensitivity of this technique for determining the substitutional boron concentration in SiGe was studied. The detection limit in the monitoring of the active dopant concentration was about 2.7 x 10^19 cm-3.
Analysis of Technology Variations in Advanced MOSFETS with the Surface-Potential-Based Compact Model HiSIM
Authors: Miura-Mattausch Mitiko , Sadachika Norio , Miyake Masataka , Yumisaki Akihiro , Mattausch Hans Juergen
Published: September 2007

Technology variations are becoming a serious and most likely dominant problem as the MOSFET size is scaled down to the 65nm node and below. Dealing with this problem requires an understanding of the origin of these variations and their precise connection to the MOSFET's engineering parameters. Here an analysis of the suitability of the advanced surface-potential-based model HiSIM for this purpose is reported. With the HiSIM model, the variation of the MOSFET characteristics are analyzed based on their physical origins, namely the variation of the fabrication technology. In particular, it is also shown that measurements for characterizing the RF performances of the MOSFET provide valuable information about microscopic fabrication-technology variaitons.
High-k Gate Stack Formation on Strained SiGe Substrate for MOSFET Applications
Authors: Zhu Chunxiang , Li MF , Huang Jidong , Fu Jia
Published: September 2007

In this paper, we examine the high-k gate stack formation on strained SiGe for p-channel MOSFET applications by comparing two different surface passivations. Experimental results show that although both surface nitridation and silicon passivation provide good MOS capacitors on SiGe substrates, the devices with ultra-thin Si passivation layer provides high hole mobility than those with surface nitridation. It is believed that nitrogen incorporation during surface nitrdation may degrade hole mobility.
Salicide Integration Optimization for Improved Yield
Authors: Towner Janet M. , Naughton John J.
Published: September 2007

Titanium silicide resistances proved to be a major impediment to yields in single and double polysilicon processes. For single level poly the problem was marginal N+ contact resistance that was resolved with a 10% reduction in the arsenic doping. For double poly processes, the N+ resistor proved to be the problem due to a lack of a wet clean prior to titanium deposition. The insertion of such a clean could not be qualified due to yield losses, however, the reduction in arsenic doping and control of screen oxide thickness were effective at reducing variations in resistance and improving yields.
Advanced DG-MOSFETs Process Technologies
Authors: Suzuki Eiichi , Liu Yongxun , Endo Kazuhiko , Matsukawa Takashi , Masahara Meisyoku , Sakamoto Kunihiro , O'uchi Shinichi
Published: September 2007

Double-gate (DG-) MOSFETs (DGFETs) have received much attention as promising silicon devices for future VLSI circuits thanks to their high short channel effects immunity. The innovative independent-double-gate four-terminal MOSFET (4T-DGFET) enables a new function of the threshold voltage controllability for the optimal power management. In this article, we present the recent progress in the fabrication processes of the fin-type DGFETs (FinFETs) and the 4T-FinFET with the separated double gates.
Challenges and Issues in 65nm CMOS Logic Technology
Authors: Lee Woo-Hyeong
Published: September 2007

CMOS logic technology has been evolving so quickly and 65nm logic technology is already in the production. In this paper, some of the common major challenges and issues of 65nm CMOS logic technology are discussed.
Comparative Study of Al-Induced Crystallization for Poly-Si and Ge on Insulating Film
Authors: Tsumura Yoshitaka , Nakao Isakane , Kanno Hiroshi , Kenjo Atsushi , Sadoh Taizoh , Miyao Masanobu
Published: September 2007

Al-induced crystallization (AIC) of Si and Ge has been comparatively investigated to realize poly-Si and poly-Ge layers on insulating films. For amorphous-Si (a-Si)/Al stacked structures, poly-Si oriented to the (111) direction was formed after annealing (450oC, 40h), and inversion of Si/Al layers occurred completely. On the other hand, poly-Ge with random orientations was formed in the local areas (diameter: 20 μm) of the Al layers after annealing (350oC, 150h) for a-Ge/Al stacked structures. In addition, inversion of Ge/Al layers did not occur. Understanding of AIC of Ge is necessary to establish a new technique for formation of high-quality poly-SiGe at low temperatures.
Effect of Fe/Si Ratio on Epitaxial Growth of Fe3Si on Ge Substrate
Authors: Kumano Mamoru , Ando Yuichiro , Ueda Koji , Sadoh Taizoh , Narumi Kazumasa , Maeda Yoshihito , Miyao Masanobu
Published: September 2007

The effects of the Fe/Si ratios on molecular beam epitaxy (MBE) of Fe3Si on Ge substrate have been investigated in a wide range of growth temperatures (60-300oC). From XRD measurements, it was found that Fe3Si layers were epitaxially grown on Ge(111) substrates at 60-200oC under the stoichiometric (Fe/Si ratio of Fe:Si=3:1) and non-stoichiometric (Fe/Si ratio of Fe:Si=4:1) conditions. From RBS measurement, it was found that atomic mixing of Fe and Ge at Fe3Si/Ge interfaces began at a growth temperature of 300oC. In the case of MBE under the stoichiometric condition (Fe:Si=3:1), the crystallinity of Fe3Si is significantly improved compared to the non-stoichiometric condition (Fe:Si=4:1). As a result, very low χmin was obtained in a wide temperature (60-200oC) under the stoichiometric condition. From the transmission electron microscopy measurements, it was shown that high-quality DO3-type Fe3Si/Ge structures with atomically flat interfaces were realized at a low temperature (~200oC) under the stoichiometric condition.
Process and Electrical Characteristics of MO-ALD HfO2 Films for High-k Gate Applications Grown in a Production Worthy 300 mm Deposition System
Authors: Clark Robert D. , Wajda Cory S. , Leusink Gert J. , Edge Lisa F. , Faltermeier Johnathan , Jamison Paul , Linder Barry P. , Copel Matthew , Narayanan Vijay , Gribelyuk Michael A. , Loesing Rainer , Murphy Richard
Published: September 2007

In this work, we present a study of the growth and electrical characteristics of metalorganic atomic layer deposited (MO-ALD) HfO2 films deposited using a 300 mm Counter-Flow ALD platform. HfO2 films were deposited over a large range of process temperatures, and flow rates in order to fully characterize the MOALD process window. The HfO2 films were characterized using AFM, HRTEM, MEIS, and SIMS. Saturation curves were generated for precursor and ozone oxidant over a 150 ºC process temperature window, using two different flow rates of Hf precursor. The use of water versus ozone as an oxidant was also investigated. Since all depositions take place above the decomposition temperature of the precursor, it is critical to understand and control the rate of thermal decomposition or parasitic CVD in the process in order to realize good uniformity in a traveling wave-type system. Thus, we have measured the rate of thermal CVD over the full range of temperatures. The thermal CVD rate shows a concave Arrhenius behavior as the process rises in temperature and transitions from an ALD dominated growth mechanism to a CVD dominated mechanism. We propose a possible explanation for this behavior. In addition to the growth characteristics, we have investigated the electrical properties of the as-deposited films using in-line Quantox measurements, and gate stack structures using integrated devices. The relationship between process and electrical characteristics will be discussed.
Drain Leakage Current Behavior in Circular Gate SOI nMOSFETs Operating from Room Temperature up to 573K
Authors: Bellodi Marcello , Almeida Luciano Mendes
Published: September 2007

In this paper is presented the drain leakage current behavior and its components that appears in circular gate SOI nMOSFETs operating since room temperature up to 573K, where it was studied the channel length and the geometrical drain bias terminal influence in the leakage current behavior when the devices are operating at high temperatures using 3-D numerical simulations. The results show that the drain leakage current depends strongly on the channel length and its density distribution is non uniform along the silicon film thickness. Besides it, also was observed that the drain leakage current depends on drain terminal position as it will be described along this paper for all devices operating at high temperatures.
Comparison Between Harmonic Distortion in Circular Gate and Conventional SOI nMOSFET Using 0.13 µm Partially-Depleted SOI CMOS Technology
Authors: Dantas Leandro P. , Gimenez Salvador P.
Published: September 2007

Harmonic distortion or Linearity is an important merit figure for low-power, low-voltage analog integrated circuit applications. This paper studies the Harmonic Distortion in Circular Gate SOI nMOSFET, using 0.13 µm Partially-Depleted SOI CMOS technology for analog applications. The drain/source asymmetric effects are considered in terms of drain current as a function of the gate and drain voltages. Circular gate SOI nMOSFET Harmonic Distortion comparisons with conventional (rectangular gate) partially-depleted SOI nMOSFET are performed, regarding the same effective channel length and width. This paper is based on experimental results. Integral Function Method (IFM) is used to determine the total harmonic distortion (THD) and third order harmonic distortion (HD3) in order to perform this work. It is observed that circular gate presents improved harmonic distortion as compared with rectangular gate SOI nMOSFETs, for the same effective channel length and width.
Defect Delineation by Electrochemical Cu Deposition in p-type Si Wafers
Authors: Kim Kwang-Salk , Ham Ho Chan , Hwang Don-Ha , Lee Bo-Young
Published: September 2007

Gate oxide integrity (GOI) is very important Si wafers, but it is very difficult to explain the origin of the oxide breakdown because the gate oxide is destroyed by the strong electric field. In this study, we detect the origin of the breakdown without destroying the gate oxide using copper reduction by the potential sweep method, followed by SEM/EDS and TEM analysis. These results show that the crystal defects near the gate oxide induce the growth of copper agglomerates without destroying the gate oxide. Hence, it can supply information on the origin of GOI fails by a simple electrochemical study.
Deposition of TiN and TaN by Remote Plasma ALD for Diffusion Barrier Applications
Authors: Knoops Harm , Baggetto L. , Langereis E. , Van de Sanden M.C.M. , Klootwijk J.H. , Roozeboom F. , Niessen R.A.H. , Notten P.H.L. , Kessels W.M.M.
Published: September 2007

TaN and TiN films were deposited by remote plasma atomic layer deposition (ALD) using the combinations of Ta(N(CH[sub]3[/sub])[sub]2[/sub])[sub]5[/sub] precursor and H[sub]2[/sub] plasma and TiCl[sub]4[/sub] precursor and H[sub]2[/sub]-N[sub]2[/sub] plasma, respectively. Both the TaN and TiN films had a cubic phase composition and films with a relatively low resistivity (TaN: 380 µΩ cm; TiN: 150 µΩ cm) were obtained. Dissimilar from the TiN properties, the material properties of the TaN films were found to depend strongly on the plasma conditions. Preliminary tests were carried out revealing the potential of the TaN and TiN films as copper and lithium diffusion barriers.
Oxidant Effect on Resistance Switching Characteristics of HfO2 film Grown Atomic Layer Deposition
Authors: Park In-Sung , Lee Jooho , Yoon Seungki , Jung Keum Jee , Lee Sunwoo , Park Jungho , Kim Chang Kyung , Ahn Jinho
Published: September 2007

The resistance switching phenomena of Mo/HfO2/Mo resistors were investigated with HfO2 films formed by using different oxidants. HfO2 films were atomic layer deposited using H2O, D2O, and O3 as oxidants, respectively. Repeatable and reliable resistance switching behaviors were obtained with H2O- and D2O-processed HfO2 films whereas O3-processed film showed only insulating breakdown. The depth profiles such as carbon in H2O- and O3-processed HfO2 films were probed using auger electron spectroscopy. The carbon content detected near the top interface of H2O-processed HfO2 film is helpful to appear the resistance switching behavior.
In-situ FTIR Study of Atomic Layer Deposition (ALD) of Copper Metal Films
Authors: Dai Min , Kwon Jinhee , Langereis E. , Wielunski Leszek S. , Chabal Yves , Li Zhengwen , Gordon Roy
Published: September 2007

Growth mechanisms of atomic layer deposition of copper films on various substrates using a novel metal precursor [Cu(sBu-amd)]2 and molecular H2 are investigated by in-situ transmission Fourier transform infrared spectroscopy (FTIR). The Cu-precursor reacts with SiO2 and Al2O3 surfaces by forming chemical bonds with the surface. Upon reduction by H2, Cu atoms agglomerate, yielding additional reactive sites for more Cu-precursors. Cu agglomeration is relatively weaker on nitrided Si surfaces. H-terminated Si surfaces show a minimal reaction with the Cu precursor. The growth rates of the Cu films on all these surfaces are all less than 1 Aå per cycle.
Nanomechanical Properties of High-K Dielectrics Grown by Atomic Layer Deposition
Authors: Tapily Kanda , Jakes Joseph , Stone Donald , Shrestha Pragya , Gu Diefeng , Baumgart Helmut , Elmustafa Abdelmageed
Published: September 2007

The challenges of reducing gate leakage current and dielectric breakdown beyond the 45 nm technology node has shifted engineers' attention from SiO2 to higher dielectric constant materials also known as high-k materials such as HfO2 and Al2O3. Therefore, it is important to investigate the electrical and mechanical properties of these materials that are projected to replace SiO2. In this study, HfO2 and Al2O3 have been deposited by atomic layer deposition (ALD) on Si wafers. Using continuous stiffness method (CSM) Nanoindenter® XP, we report elasto-mechanical properties of HfO2 and Al2O3 on Si. HfO2 has a hardness and modulus of 9-10 {plus minus} 2 GPA and 200 {plus minus} 40 GPA respectively. In addition, the hardness and modulus of Al2O3 were determined to be respectively 10-11 {plus minus} 2 GPA and 200 {plus minus} 40 GPA.
Atomic Layer Deposition of Hafnium Based Gate Dielectric Layers for CMOS Applications
Authors: Delabie Annelies , Nyns Laura , Bellenger Florence , Caymax Matty , Conard Thierry , Franquet Alexis , Houssa Michel , Lin D. , Meuris Marc , Ragnarsson Lars-Aåke , Sioncke Sonja , Swerts Johan , Fedorenko Yanina , Maes Jan Willem , Van Elshocht Sven , De Gendt Stefan
Published: September 2007

To increase CMOS device performance, new materials are introduced in the gate stack (high-k dielectrics, metal gates) and the transistor channel (Ge, III-V). In this work, we study the Atomic Layer Deposition (ALD) of hafnium based gate dielectric oxides. Depositing by means of surface controlled reactions implies that the chemical sites at the surface can determine the growth behavior. First, the starting surface effect is analyzed for HfO2 ALD on Ge and GaAs substrates. Either substrate inhibition or enhancement occurs, both associated with an initial regime of island growth. The presence of oxygen enhances the GPC in the first reaction cycle. Second, the steady ALD of ternary oxides (hafnium silicate, aluminate, zirconate) is discussed. HfCl4 (and ZrCl4) chemisorption are much less affected by the composition of ternary oxides than by the starting surface. On the other hand, the SiCl4 chemisorption rate is significantly affected by the Hf-content of hafnium silicates.
Tuning the Absolute Band Gap of Silicon Photonic Crystals by Atomic Layer Deposition (ALD) Interfacial Layers
Authors: Thitsa Makhin , Gu Diefeng , Baumgart Helmut , Albin Sacharia
Published: September 2007

We modeled the two dimensional photonic crystal consisting of air cylinders in silicon background by using plane wave expansion method. In this particular structure, the absolute band gap can be tuned only in a small range of normalized radii (0.404-0.48). Within this range, the band gap changes rapidly with the air cylinder radius due to the high dielectric constant of silicon. In addition, we modeled the structures with interfacial layers of Al2O3 and SiO2 deposited by atomic layer deposition (ALD).As the thickness of the deposited layer varies from 0 to 0.05a, the band gap changes respectively by 3.7% and 2.5% for Al2O3 and SiO2. For a photonic crystal of lattice constant a = 400nm, the interfacial layer thickness is equivalent to 20nm, which is well within the scale that can be accurately controlled by ALD. Therefore, fine tuning of photonic band gap can be achieved by ALD.
Electrodeposition of PbS Multilayers on AG(111) by ECALE (Electrochemical Atomic Layer Epitaxy)
Authors: Fernandes Valeria C. , Salvietti Emanuelle , Loglio Francesca , Innocenti Massimo , Mascaro Lucia , Foresti Maria
Published: September 2007

Lead sulfide (PbS) thin films were grown on single crystal Ag(111) substrate. PbS films were obtained by Electrochemical Atomic Layer Epitaxy (ECALE) method, that is by alternated underpotential deposition (UPD) of lead and sulfur. The voltammetric analysis of the first PbUPD and SUPD peaks indicates a mechanism of two-dimensional growth, which is consistent with epitaxial growth. Electrochemical stripping measurements indicate that amount of Pb and S deposited in a given number of cycles is a function of the number of cycles employed, again suggesting a layer-by-layer growth. The stripping charges associated with each layer of Pb and S was 87 μC cm-2. This result suggests that amount of Pb and S in these films corresponds to the stoichiometric 1:1 ratio, indicating the formation of a compound.
Evolution of Silicon Cleaning Technology Over the Last Twenty Years
Authors: Ruzyllo J. , Hattori Takeshi , Novak Richard E. , Mertens P. , Besson P.
Published: September 2007

This paper briefly summarizes selected developments that were marking progress in silicon cleaning technology over the last twenty years. The occasion for this review is a 10th International Symposium on Cleaning and Surface Conditioning Technology in Semiconductor Device Manufacturing organized under the auspices of the Electrochemical Society. This review considers general trends underlying the progress in cleaning technology, specific developments in the area of removal of various types of contaminants, as well as cleaning metrology. The concluding observation from this review is that the wafer cleaning technology is keeping up with increasing needs through continuous progress in all its facets. This progress will need to continue if the challenges resulting from increased complexity of device structures, new materials used, and the need to address environmental concerns are to be resolved.