443 research outputs found
Metrology of EUV Masks by EUV-Scatterometry and Finite Element Analysis
Extreme ultraviolet (EUV) lithography is seen as a main candidate for
production of future generation computer technology. Due to the short
wavelength of EUV light (around 13 nm) novel reflective masks have to be used
in the production process. A prerequisite to meet the high quality requirements
for these EUV masks is a simple and accurate method for absorber pattern
profile characterization. In our previous work we demonstrated that the Finite
Element Method (FEM) is very well suited for the simulation of EUV
scatterometry and can be used to reconstruct EUV mask profiles from
experimental scatterometric data. In this contribution we apply an indirect
metrology method to periodic EUV line masks with different critical dimensions
(140 nm and 540 nm) over a large range of duty cycles (1:2, ..., 1:20). We
quantitatively compare the reconstructed absorber pattern parameters to values
obtained from direct AFM and CD-SEM measurements. We analyze the reliability of
the reconstruction for the given experimental data. For the CD of the absorber
lines, the comparison shows agreement of the order of 1nm. Furthermore we
discuss special numerical techniques like domain decomposition algorithms and
high order finite elements and their importance for fast and accurate solution
of the inverse problem.Comment: Photomask Japan 2008 / Photomask and Next-Generation Lithography Mask
Technology X
Rigorous FEM-Simulation of EUV-Masks: Influence of Shape and Material Parameters
We present rigorous simulations of EUV masks with technological imperfections
like side-wall angles and corner roundings. We perform an optimization of two
different geometrical parameters in order to fit the numerical results to
results obtained from experimental scatterometry measurements. For the
numerical simulations we use an adaptive finite element approach on irregular
meshes. This gives us the opportunity to model geometrical structures
accurately. Moreover we comment on the use of domain decomposition techniques
for EUV mask simulations. Geometric mask parameters have a great influence on
the diffraction pattern. We show that using accurate simulation tools it is
possible to deduce the relevant geometrical parameters of EUV masks from
scatterometry measurements.
This work results from a collaboration between Advanced Mask Technology
Center (AMTC, mask fabrication), Physikalisch-Technische Bundesanstalt (PTB,
scatterometry), Zuse Institute Berlin (ZIB), and JCMwave (numerical
simulation).Comment: 8 pages, 8 figures (see original publication for images with a better
resolution
Theoretical Summary of the HADRON99 conference
The Constituent Quark Model has provided a remarkable description of the
experimentally observed hadron spectrum but still has no firm theoretical
basis. Attempts to provide a QCD justification discussed at Hadron99 include
QCD Sum Rules, instantons, relativistic potential models and the lattice.
Phenomenological analyses to clarify outstanding problems like the nature of
the scalar and pseudoscalar mesons and the low branching ratio for were presented. New experimental puzzles include the observation of
.Comment: 10 pages, espcrc1.st
Asymptotic Level Density of the Elastic Net Self-Organizing Feature Map
Whileas the Kohonen Self Organizing Map shows an asymptotic level density
following a power law with a magnification exponent 2/3, it would be desired to
have an exponent 1 in order to provide optimal mapping in the sense of
information theory. In this paper, we study analytically and numerically the
magnification behaviour of the Elastic Net algorithm as a model for
self-organizing feature maps. In contrast to the Kohonen map the Elastic Net
shows no power law, but for onedimensional maps nevertheless the density
follows an universal magnification law, i.e. depends on the local stimulus
density only and is independent on position and decouples from the stimulus
density at other positions.Comment: 8 pages, 10 figures. Link to publisher under
http://link.springer.de/link/service/series/0558/bibs/2415/24150939.ht
SELEX RICH Performance and Physics Results
SELEX took data in the 1996/7 Fixed Target Run at Fermilab. The excellent
performance parameters of the SELEX RICH Detector had direct influence on the
quality of the obtained physics results.Comment: Contributed talk at the Fourth Workshop on RICH Detectors, June 5-10,
2002, Pylos, Greece. Accepted for publication in NIM
Experimental evidence of a fractal dissipative regime in high-T_c superconductors
We report on our experimental evidence of a substantial geometrical
ingredient characterizing the problem of incipient dissipation in high-T_c
superconductors(HTS): high-resolution studies of differential
resistance-current characteristics in absence of magnetic field enabled us to
identify and quantify the fractal dissipative regime inside which the actual
current-carrying medium is an object of fractal geometry. The discovery of a
fractal regime proves the reality and consistency of critical-phenomena
scenario as a model for dissipation in inhomogeneous and disordered HTS, gives
the experimentally-based value of the relevant finite-size scaling exponent and
offers some interesting new guidelines to the problem of pairing mechanisms in
HTS.Comment: 5 pages, 3 figures, RevTex; Accepted for publication in Physical
Review B; (figures enlarged
Opioid Receptor Probes Derived from Cycloaddition of the Hallucinogen Natural Product Salvinorin A
As part of our continuing efforts toward more fully understanding the structureâactivity relationships of the neoclerodane diterpene salvinorin A, we report the synthesis and biological characterization of unique cycloadducts through [4+2] DielsâAlder cycloaddition. Microwave-assisted methods were developed and successfully employed, aiding in functionalizing the chemically sensitive salvinorin A scaffold. This demonstrates the first reported results for both cycloaddition of the furan ring and functionalization via microwave-assisted methodology of the salvinorin A skeleton. The cycloadducts yielded herein introduce electron-withdrawing substituents and bulky aromatic groups into the C-12 position. Kappa opioid (KOP) receptor space was explored through aromatization of the bent oxanorbornadiene system possessed by the cycloadducts to a planar phenyl ring system. Although dimethyl- and diethylcarboxylate analogues 5 and 6 retain some affinity and selectivity for KOP receptors and are full agonists, their aromatized counterparts 13 and 14 have reduced affinity for KOP receptors. The methods developed herein signify a novel approach toward rapidly probing the structureâactivity relationships of furan-containing natural products
Influence of Poly(L-Lactic Acid) Nanofibers and BMP-2âContaining Poly(L-Lactic Acid) Nanofibers on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells
The aim of this study was to characterize synthetic poly-(L-lactic acid) (PLLA) nanofibers concerning their ability to promote growth and osteogenic differentiation of stem cells in vitro, as well as to test their suitability as a carrier system for growth factors. Fiber matrices composed of PLLA or BMP-2âincorporated PLLA were seeded with human mesenchymal stem cells and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of alkaline phosphatase (ALP), osteocalcin (OC), and collagen I (COL-I). Furthermore, COL-I and OC deposition, as well as cell densities and proliferation, were analyzed using fluorescence microscopy. Although the presence of nanofibers diminished the dexamethasone-induced proliferation, there were no differences in cell densities or deposition of either COL-I or OC after 22 days of culture. The gene expression of ALP, OC, and COL-I decreased in the initial phase of cell cultivation on PLLA nanofibers as compared to cover slip control, but normalized during the course of cultivation. The initial down-regulation was not observed when BMP-2 was directly incorporated into PLLA nanofibers by electrospinning, indicating that growth factors like BMP-2 might survive the spinning process in a bioactive form
Effect of Dopant on the Nanostructured Morphology of Poly (1-naphthylamine) Synthesized by Template Free Method
The study reports some preliminary investigations on the template free synthesis of ascantlyinvestigated polyaniline (PANI) derivativeâpoly (1-naphthylamine) (PNA) by template free method in presence as well as absence of hydrochloric acid (HCl) (dopant), using ferric chloride as oxidant. The polymerization was carried out in alcoholic medium. Polymerization of 1-naphthylamine (NPA) was confirmed by the FT-IR as well as UVâvisible studies. The morphology and size of PNA particles was strongly influenced by the presence and absence of acid which was confirmed by transmission electron microscopy (TEM) studies
Identification of a Novel âAlmost Neutralâ Mu Opioid Receptor Antagonist in CHO Cells Expressing the Cloned Human Mu Opioid Receptor
The basal (constitutive) activity of G protein-coupled receptors allows for the measurement of inverse agonist activity. Some competitive antagonists turn into inverse agonists under conditions where receptors are constitutively active. In contrast, neutral antagonists have no inverse agonist activity, and they block both agonist and inverse agonist activity. The mu opioid receptor (MOR) demonstrates detectable constitutive activity only after a state of dependence is produced by chronic treatment with a MOR agonist. We therefore sought to identify novel MOR inverse agonists, and novel neutral MOR antagonists in both untreated and agonist-treated MOR cells. CHO cells expressing the cloned human mu receptor (hMOR-CHO cells) were incubated for 20 hr with medium (control) or 10 ÎŒM (2S,4aR,6aR,7R,9S,10aS,10bR)-9-(benzoyloxy)-2-(3-furanyl)dodecahydro-6a,10b-dimethyl-4,10-dioxo-2H-naphtho-[2,1-c]pyran-7-carboxylic acid methyl ester (herkinorin, HERK). HERK-treatment generates a high degree of basal signaling and enhances the ability to detect inverse agonists. [35S]-GTP-Îł-S assays were conducted using established methods. We screened 21 MOR âantagonistsâ using membranes prepared from HERK-treated hMOR-CHO cells. All antagonists, including CTAP and 6ÎČ-naltrexol, were inverse agonists. However, LTC-2 7 4 ( (-)-3-cyclopropylmethyl-2,3,4,4aα,5,6,7,7aα-octahydro-1H-benzofuro[3,2-e]isoquinolin-9-ol)) showed the lowest efficacy as an inverse agonist, and, at concentrations less than 5 nM, had minimal effects on basal [35S]-GTP-Îł-S binding. Other efforts in this study identified KC-2-009 ((+)-3-((1R,5S)-2-((Z)-3-Phenylallyl)-2-azabicyclo[3.3.1]nonan-5-yl)phenol hydrochloride) as an inverse agonist at untreated MOR cells. In HERK-treated cells, KC-2-009 had the highest efficacy as an inverse agonist. In summary, we identified a novel and selective MOR inverse agonist (KC-2-009), and a novel MOR antagonist (LTC-274) that shows the least inverse agonist activity among 21 MOR antagonists. LTC-274 is a promising lead compound for developing a true MOR neutral antagonist
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