5,426 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
Scales for co-compact embeddings of virtually free groups
Let be a group which is virtually free of rank at least 2 and let
be the family of totally disconnected, locally
compact groups containing as a co-compact lattice.
We prove that the values of the scale function with respect to groups in
evaluated on the subset have only finitely
many prime divisors. This can be thought of as a uniform property of the family
.Comment: 12 pages; key words: uniform lattice, virtually free group, totally
disconnected group, scale function (Error in references corrected in version
2
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
Sensitivity of DF-ICP-MS, PERALS and alpha-spectrometry for the determination of actinides: A comparison
We applied three techniques (DF-ICP-MS, PERALS and alpha-spectrometry) for the determination of minor actinides at environmental levels. For each method the limit of detection and the resolution were estimated in order to study the content and isotopic composition of the actinides. Two international reference materials, IAEA-135 (Irish Sea Sediment) and IAEA-300 (Baltic Sea sediment) were analyzed for activity concentrations of 238Pu, 239Pu, 240Pu, 241Pu and 241Am. The sensitivities of the three determination techniques were compare
Optical microscopy via spectral modifications of a nano-antenna
The existing optical microscopes form an image by collecting photons emitted
from an object. Here we report on the experimental realization of microscopy
without the need for direct optical communication with the sample. To achieve
this, we have scanned a single gold nanoparticle acting as a nano-antenna in
the near field of a sample and have studied the modification of its intrinsic
radiative properties by monitoring its plasmon spectrum.Comment: 6 pages, 4 figures (color
Scaling Study and Thermodynamic Properties of the cubic Helimagnet FeGe
The critical behavior of the cubic helimagnet FeGe was obtained from
isothermal magnetization data in very close vicinity of the ordering
temperature. A thorough and consistent scaling analysis of these data revealed
the critical exponents , , and . The
anomaly in the specific heat associated with the magnetic ordering can be well
described by the critical exponent . The values of these
exponents corroborate that the magnetic phase transition in FeGe belongs to the
isotropic 3D-Heisenberg universality class. The specific heat data are well
described by ab initio phonon calculations and confirm the localized character
of the magnetic moments.Comment: 10 pages, 8 figure
Time Pressure, Time Autonomy, and Sickness Absenteeism in Hospital Employees: A Longitudinal Study on Organizational Absenteeism Records
Background
Although work absenteeism is in the focus of occupational health, longitudinal studies on organizational absenteeism records in hospital work are lacking. This longitudinal study tests time pressure and lack of time autonomy to be related to higher sickness absenteeism.
Methods
Data was collected for 180 employees (45% nurses) of a Swiss hospital at baseline and at follow-up after 1 year. Absent times (hours per month) were received from the human resources department of the hospital. One-year follow-up of organizational absenteeism records were regressed on self-reported job satisfaction, time pressure, and time autonomy (i.e., control) at baseline.
Results
A multivariate regression showed significant prediction of absenteeism by time pressure at baseline and time autonomy, indicating that a stress process is involved in some sickness absenteeism behavior. Job satisfaction and the interaction of time pressure and time autonomy did not predict sickness absenteeism.
Conclusion
Results confirmed time pressure and time autonomy as limiting factors in healthcare and a key target in work redesign.
Keywords
healthcare ; occupational health ; time autonomy ; work absenteeism ; work stres
Performance of the AMS-02 Transition Radiation Detector
For cosmic particle spectroscopy on the International Space Station the AMS
experiment will be equipped with a Transition Radiation Detector (TRD) to
improve particle identification. The TRD has 20 layers of fleece radiator with
Xe/CO2 proportional mode straw tube chambers. They are supported in a conically
shaped octagon structure made of CFC-Al-honeycomb. For low power consumption VA
analog multiplexers are used as front-end readout. A 20 layer prototype built
from final design components has achieved proton rejections from 100 to 2000 at
90% electron efficiency for proton beam energies up to 250 GeV with cluster
counting, likelihood and neural net selection algorithms.Comment: 11 pages, 25 figures, espcrc2.sty (elsevier 2-column
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