1,721,012 research outputs found
Microdomain orientation dependence on thickness in thin films of cylinder-forming PS-b-PMMA
Full text linkThe self-assembly of block-copolymer thin films in periodic nanostructures has received considerable attention during the last decade due to their potential applications in nanofabrication and nanolithography. We followed the morphologies developed in thin films of a cylinder-forming diblock copolymer polystyrene-b-poly(methylmethacrylate) ((PS-b-PMMA), PS 46.1 kg mol−1, PMMA 21.0 kg mol−1, lattice spacing L0 = 36 nm), as a function of the film thickness (t), analyzing the effect of thickness commensurability on domain
orientation in respect to the substrate. The study was circumscribed to the unexplored range of thickness below L0. Two thickness windows with perpendicular orientation of the PMMA domains were identified: a well-known window at t ~ L0 and a new window at t ~L0/2. A half-parallel cylinder morphology was observed for t ~ ¾ L0 with a progressive change in
morphology C┴ → C|| → C┴ when thickness increases from L0/2 to L0. This experimental evidence provides new insights on the mechanism of block copolymers self-organization and indicates the possibility to tune the thickness of the nanostructured polymeric film below L0, allowing the fabrication of ultrathin soft masks for advanced lithographic processes.Fil: Zucchi, Ileana Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina. Istituto Nazionale per la Fisica della Materia; ItaliaFil: Poliani, Emanuele. Istituto Nazionale per la Fisica della Materia; ItaliaFil: Perego, Michele. Istituto Nazionale per la Fisica della Materia; Itali
Technological strategies for self-assembly of PS-b-PDMS in cylindrical sub-10 nm nanostructures for lithographic applications
No full textThe continuous demand for small portable electronics is pushing the semiconductor industry to develop novel lithographic methods to fabricate the elementary structures for microelectronics devices with dimensions below 10 nm. Top-down strategies include multiple patterning photolithography, extreme ultraviolet lithography (EUVL), electron beam lithography (EBL), and nanoimprint lithography. Bottom-up approaches mainly rely on block copolymers (BCPs) self-assembly (SA). SA of BCPs is extremely appealing due to its excellent compatibility with conventional photolithographic processes, high-resolution patterns, and low process costs. Among the various BCPs, the polystyrene-b-polydimethylsiloxane (PS-b-PDMS) represents the most investigated material for the fabrication of sub-10 nm structures. However, PS-b-PDMS cannot be easily processed by conventional thermal treatments due to its slow SA kinetic coupled with a relatively low thermal stability. This review focuses on the available annealing methods to promote the SA PS-b-PDMS in parallel-oriented cylindrical sub-10 nm structures. Moreover, literature data regarding the annealing time, defects density, line edge roughness (LER) and line width roughness ( LWR) are discussed with reference to the stringent requirements of semiconductor technology
Ordering kinetics in two-dimensional hexagonal pattern of cylinder-forming PS-b-PMMA block copolymer thin films: Dependence on the segregation strength
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Bottom-Up Assembly of Micro/Nanostructures
No full textGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and Material
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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