4,096 research outputs found
Noncontact electrical metrology of Cu/low-k interconnect for semiconductor production wafers
We have demonstrated a technique capable of in-line measurement of dielectric
constant of low-k interconnect films on patterned wafers utilizing a test key
of ~50x50 \mu m in size. The test key consists of a low-k film backed by a Cu
grid with >50% metal pattern density and <250 nm pitch, which is fully
compatible with the existing dual-damascene interconnect manufacturing
processes. The technique is based on a near-field scanned microwave probe and
is noncontact, noninvasive, and requires no electrical contact to or grounding
of the wafer under test. It yields <0.3% precision and 2% accuracy for the film
dielectric constant
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High-Speed, Compact, Adaptive Lenses Using In-Line Transparent Dielectric Elastomer Actuator Membranes
Electrically tunable adaptive lenses provide several advantages over traditional lens assemblies in terms of compactness, speed, efficiency, and flexibility. We present an elastomer-liquid lens system which makes use of an in-line, transparent electroactive polymer actuator. The lens has two liquid-filled cavities enclosed within two frames, with two passive outer elastomer membranes and an internal transparent electroactive membrane. Advantages of the lens design over existing systems include large apertures, flexibility in choosing the starting lens curvature, and electrode encapsulation with a dielectric liquid. A lens power change up to 40 diopters, corresponding to focal length variation up to 300%, was recorded during actuation, with a response time on the order of tens of milliseconds.Engineering and Applied Science
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Tunable Lenses Using Transparent Dielectric Elastomer Actuators
Focus tunable, adaptive lenses provide several advantages over traditional lens assemblies in terms of compactness, cost, efficiency, and flexibility. To further improve the simplicity and compact nature of adaptive lenses, we present an elastomer-liquid lens system which makes use of an inline, transparent electroactive polymer actuator. The lens requires only a minimal number of components: a frame, a passive membrane, a dielectric elastomer actuator membrane, and a clear liquid. The focal length variation was recorded to be greater than 100% with this system, responding in less than one second. Through the analysis of membrane deformation within geometrical constraints, it is shown that by selecting appropriate lens dimensions, even larger focusing dynamic ranges can be achieved.Engineering and Applied Science
Uncovering predictability in the evolution of the WTI oil futures curve
Accurately forecasting the price of oil, the world's most actively traded
commodity, is of great importance to both academics and practitioners. We
contribute by proposing a functional time series based method to model and
forecast oil futures. Our approach boasts a number of theoretical and practical
advantages including effectively exploiting underlying process dynamics missed
by classical discrete approaches. We evaluate the finite-sample performance
against established benchmarks using a model confidence set test. A realistic
out-of-sample exercise provides strong support for the adoption of our approach
with it residing in the superior set of models in all considered instances.Comment: 28 pages, 4 figures, to appear in European Financial Managemen
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Hadron--hadron reactions, high multiplicity. [Review]
A coverage of results on high energy and high multiplicity hadron reactions, charm searches and related topics, ultrahigh energy events and exotic phenomena (cosmic rays), and the nuclear effects in high energy collisions and related topics is discussed. 67 references. (JFP
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Effect of Silane Coupling Agent Chemistry on Electrical Breakdown across Hybrid Organic–Inorganic Insulating Films
Dielectric breakdown measurements were conducted on self-assembled monolayer (SAM)/native silicon oxide hybrid dielectrics using conductive atomic force microscopy (C-AFM). By depositing silane coupling agents (SCAs) through a diffusional barrier layer, SAM roughness was decoupled from chemistry to compare the chemical effects of exposed R-group functionality on dielectric breakdown. Using Weibull and current–voltage (I–V) analysis, the breakdown strength was observed to be independent of SCA R-group length, and the addition of a SAM was seen to improve the breakdown strength relative to native silicon oxide by up to 158%. Fluorinated SCAs were observed to suppress tunneling leakage and exhibited increased breakdown strength relative to their hydrocarbon analogs. Electron trapping, scattering, or attachment processes inherent to the fluorinated moieties are thought to be the origin of the improved breakdown properties.Engineering and Applied Science
Theoretical Analysis of STM Experiments at Rutile TiO_2 Surfaces
A first-principles atomic orbital-based electronic structure method is used
to investigate the low index surfaces of rutile Titanium Dioxide. The method is
relatively cheap in computational terms, making it attractive for the study of
oxide surfaces, many of which undergo large reconstructions, and may be
governed by the presence of Oxygen vacancy defects. Calculated surface charge
densities are presented for low-index surfaces of TiO, and the relation of
these results to experimental STM images is discussed. Atomic resolution images
at these surfaces tend to be produced at positive bias, probing states which
largely consist of unoccupied Ti 3 bands, with a small contribution from O
2. These experiments are particularly interesting since the O atoms tend to
sit up to 1 angstrom above the Ti atoms, so providing a play-off between
electronic and geometric structure in image formation.Comment: 9 pages, Revtex, 3 postscript figures, accepted by Surf. Scienc
Hybrid Software Development Approaches in Practice: A European Perspective
Agile and traditional development approaches are used in combination in todays software development. To improve the understanding and to provide better guidance for selecting appropriate development approaches, it is important to analyze such combinations in practice. Results obtained from an online survey strongly confirm that hybrid development approaches are widely used in industry. Our results show that hybrid development approaches: (i) have become reality for nearly all companies; (ii) are applied to specific projects even in the presence of company-wide policies for process usage; (iii) are neither planned nor designed but emerge from the evolution of different work practices; and, (iv) are consistently used regardless of company size or industry secto
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