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Development of a new analysis technique for plasma etched nanostructures : Quasi in-situ TEM EDX characterization
No full textAvec la diminution perpétuelle des dimensions des circuits intégrés, la gravure de dispositifs à l’échelle nanométrique constitue un véritable défi pour les procédés plasma qui montrent des limites dans le cas d’empilement de couches minces notamment. L’anisotropie de gravure réside sur la formation de couches de passivations sur les flancs des motifs, qui agissent comme film protecteur bloquant la gravure latérale par les radicaux du plasma. Cependant, cette fine couche est responsable de l’apparition de pente dans les profils gravés et il est difficile de contrôler son épaisseur. De plus, une deuxième couche réactive est aussi formée en fond de motifs. Les produits de gravures sont formés au sein de cette couche permettant d’augmenter la vitesse de gravure du substrat. Il a récemment été admis que contrôler l’épaisseur de ces couches réactives constitue le paramètre clé pour obtenir une gravure à très haute sélectivité.Cependant, les couches réactives à analyser hautement réactives, en raison de leur forte concentration en halogènes, s’oxydent immédiatement lors de la remise à l’air.Cette étude se propose de développer une approche originale, simple et extrêmement puissante pour observer ces couches de passivation quasi in-situ (sans contact avec l’air ambiant) : Apres gravure, l’échantillon est transporté sous vide à l’intérieur d’une valise spécifique jusqu’à une enceinte de dépôt, où il est alors encapsulé par une couche métallique (PVD assisté par magnétron). L’échantillon ainsi encapsulé peut être observé ex-situ sans modification chimique grâce à des analyses STEM EDX.As the size of integrated circuit continues to shrink, plasma processes are more and more challenged and show limitations to etch nanometer size features in complex stacks of thin layers. The achievement of anisotropic etching relies on the formation of passivation layers on the sidewalls of the etched features, which act like a protective film that prevents lateral etching by the plasma radicals. However, this layer also generate a slope in the etch profile and it’s difficult to control its thickness. Another thin layer called “reactive layer” is also formed at the bottom of the features. Etch products are formed in this layer allowing a high etch rate of the substrate. It starts to be realized that controlling the thickness of this reactive layer is the key to achieve very high selective processes.However, the layers to be analyzed are chemically highly reactive because they contain large concentrations of halogens and they get immediately modified (oxidized) when exposed to ambient atmosphere.In this work we develop an original, simple and extremely powerful approach to observe passivation layers quasi in-situ (i.e. without air exposure): After plasma etching, the wafer is transported under vacuum inside an adapted suitcase to a deposition chamber where it is encapsulated by a metallic layer (magnetron sputtering PVD). Then, the encapsulated features can be observed ex situ without chemical / thickness modification thanks to (S)TEM-EDX analysis
Développement d'une nouvelle technique d'analyse pour les nanosctructures gravées par plasmas : (S)TEM EDX quasi in-situ
No full textAs the size of integrated circuit continues to shrink, plasma processes are more and more challenged and show limitations to etch nanometer size features in complex stacks of thin layers. The achievement of anisotropic etching relies on the formation of passivation layers on the sidewalls of the etched features, which act like a protective film that prevents lateral etching by the plasma radicals. However, this layer also generate a slope in the etch profile and it’s difficult to control its thickness. Another thin layer called “reactive layer” is also formed at the bottom of the features. Etch products are formed in this layer allowing a high etch rate of the substrate. It starts to be realized that controlling the thickness of this reactive layer is the key to achieve very high selective processes.However, the layers to be analyzed are chemically highly reactive because they contain large concentrations of halogens and they get immediately modified (oxidized) when exposed to ambient atmosphere.In this work we develop an original, simple and extremely powerful approach to observe passivation layers quasi in-situ (i.e. without air exposure): After plasma etching, the wafer is transported under vacuum inside an adapted suitcase to a deposition chamber where it is encapsulated by a metallic layer (magnetron sputtering PVD). Then, the encapsulated features can be observed ex situ without chemical / thickness modification thanks to (S)TEM-EDX analysis.Avec la diminution perpétuelle des dimensions des circuits intégrés, la gravure de dispositifs à l’échelle nanométrique constitue un véritable défi pour les procédés plasma qui montrent des limites dans le cas d’empilement de couches minces notamment. L’anisotropie de gravure réside sur la formation de couches de passivations sur les flancs des motifs, qui agissent comme film protecteur bloquant la gravure latérale par les radicaux du plasma. Cependant, cette fine couche est responsable de l’apparition de pente dans les profils gravés et il est difficile de contrôler son épaisseur. De plus, une deuxième couche réactive est aussi formée en fond de motifs. Les produits de gravures sont formés au sein de cette couche permettant d’augmenter la vitesse de gravure du substrat. Il a récemment été admis que contrôler l’épaisseur de ces couches réactives constitue le paramètre clé pour obtenir une gravure à très haute sélectivité.Cependant, les couches réactives à analyser hautement réactives, en raison de leur forte concentration en halogènes, s’oxydent immédiatement lors de la remise à l’air.Cette étude se propose de développer une approche originale, simple et extrêmement puissante pour observer ces couches de passivation quasi in-situ (sans contact avec l’air ambiant) : Apres gravure, l’échantillon est transporté sous vide à l’intérieur d’une valise spécifique jusqu’à une enceinte de dépôt, où il est alors encapsulé par une couche métallique (PVD assisté par magnétron). L’échantillon ainsi encapsulé peut être observé ex-situ sans modification chimique grâce à des analyses STEM EDX
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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