1,398 research outputs found
Near-field scanning microwave microscope for interline capacitance characterization of nanoelectronics interconnect
We have developed a noncontact method for measurement of the interline
capacitance in Cu/low-k interconnect. It is based on a miniature test vehicle
with net capacitance of a few femto-Farads formed by two 20-\mu m-long parallel
wires (lines) with widths and spacings the same as those of the interconnect
wires of interest. Each line is connected to a small test pad. The vehicle
impedance is measured at 4 GHz by a near-field microwave probe with 10 \mu m
probe size via capacitive coupling of the probe to the vehicle's test pads.
Full 3D finite element modeling at 4 GHz confirms that the microwave radiation
is concentrated between the two wires forming the vehicle. An analytical lumped
element model and a short/open calibration approach have been proposed to
extract the interline capacitance value from the measured data. We have
validated the technique on several test vehicles made with copper and low-k
dielectric on a 300 mm wafer. The vehicles interline spacing ranges from 0.09
to 1 \mu m and a copper line width is 0.15 \mu m. This is the first time a
near-field scanning microwave microscope has been applied to measure the lumped
element impedance of a test vehicle
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
A near-field scanned microwave probe for spatially localized electrical metrology
We have developed a near-field scanned microwave probe with a sampling volume
of approximately 10 micron in diameter, which is the smallest one achieved in
near-field microwave microscopy. This volume is defined to confine close to 100
percent of the probe net sampling reactive energy, thus making the response
virtually independent on the sample properties outside of this region. The
probe is formed by a 4 GHz balanced stripline resonator with a few-micron tip
size. It provides non-contact, non-invasive measurement and is uniquely suited
for spatially localized electrical metrology applications, e.g. on
semiconductor production wafers.Comment: 6 pages, 3 figures, submitted to Appl. Phys. Let
Constraints on the perturbed mutual motion in Didymos due to impact-induced deformation of its primary after the DART impact
Binary near-Earth asteroid (65803) Didymos is the target of the proposed NASA
Double Asteroid Redirection Test (DART), part of the Asteroid Impact &
Deflection Assessment (AIDA) mission concept. In this mission, the DART
spacecraft is planned to impact the secondary body of Didymos, perturbing
mutual dynamics of the system. The primary body is currently rotating at a spin
period close to the spin barrier of asteroids, and materials ejected from the
secondary due to the DART impact are likely to reach the primary. These
conditions may cause the primary to reshape, due to landslides, or internal
deformation, changing the permanent gravity field. Here, we propose that if
shape deformation of the primary occurs, the mutual orbit of the system would
be perturbed due to a change in the gravity field. We use a numerical
simulation technique based on the full two-body problem to investigate the
shape effect on the mutual dynamics in Didymos after the DART impact. The
results show that under constant volume, shape deformation induces strong
perturbation in the mutual motion. We find that the deformation process always
causes the orbital period of the system to become shorter. If surface layers
with a thickness greater than ~0.4 m on the poles of the primary move down to
the equatorial region due to the DART impact, a change in the orbital period of
the system and in the spin period of the primary will be detected by
ground-based measurement.Comment: 8 pages, 7 figures, 2 tables, accepted for publication in MNRA
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Diabetes, Obesity, and Hypertension May Enhance Associations between Air Pollution and Markers of Systemic Inflammation
Airborne particulate matter (PM) may lead to increased cardiac risk through
an inflammatory pathway. Therefore, we investigated associations
between ambient PM and markers of systemic inflammation among repeated
measures from 44 senior citizens (≥ 60 years of age) and examined
susceptibility by conditions linked to chronic inflammation. Mixed
models were used to identify associations between concentrations of
fine PM [aerodynamic diameter ≤ 2.5 μm (PM2.5)] averaged over 1–7 days and measures of C-reactive protein (CRP), interleukin-6 (IL-6), and white blood cells (WBCs). Effect
modification was investigated for diabetes, obesity, hypertension, and
elevated mean inflammatory markers. We found positive associations
between longer moving averages of PM2.5 and WBCs across all participants, with a 5.5% [95% confidence
interval (CI), 0.10 to 11%] increase per
interquartile increase (5.4 μg/m3) of PM2.5 averaged over the previous week. PM2.5 and CRP also exhibited positive associations among all individuals for
averages longer than 1 day, with the largest associations for persons
with diabetes, obesity, and hypertension. For example, an interquartile
increase in the 5-day mean PM2.5 (6.1 μg/m3) was associated with a 14% increase in CRP (95% CI, −5.4 to 37%) for all individuals and an 81% (95% CI, 21 to 172%) increase for persons with diabetes, obesity, and
hypertension. Persons with diabetes, obesity, and hypertension
also exhibited positive associations between PM2.5 and IL-6. Individuals with elevated mean inflammatory markers exhibited
enhanced associations with CRP, IL-6, and WBCs. We found modest positive
associations between PM2.5 and indicators of systemic inflammation, with larger associations suggested
for individuals with diabetes, obesity, hypertension, and elevated
mean inflammatory markers
Prevalence of Masked Hypertension Among US Adults With Nonelevated Clinic Blood Pressure
Masked hypertension (MHT), defined as nonelevated blood pressure (BP) in the clinic setting and elevated BP assessed by ambulatory monitoring, is associated with increased risk of target organ damage, cardiovascular disease, and mortality. Currently, no estimate of MHT prevalence exists for the general US population. After pooling data from the Masked Hypertension Study (n = 811), a cross-sectional clinical investigation of systematic differences between clinic BP and ambulatory BP (ABP) in a community sample of employed adults in the New York City metropolitan area (2005-2012), and the National Health and Nutrition Examination Survey (NHANES; 2005-2010; n = 9,316), an ongoing nationally representative US survey, we used multiple imputation to impute ABP-defined hypertension status for NHANES participants and estimate MHT prevalence among the 139 million US adults with nonelevated clinic BP, no history of overt cardiovascular disease, and no use of antihypertensive medication. The estimated US prevalence of MHT in 2005-2010 was 12.3% of the adult population (95% confidence interval: 10.0, 14.5)-approximately 17.1 million persons aged ≥21 years. Consistent with prior research, estimated MHT prevalence was higher among older persons, males, and those with prehypertension or diabetes. To our knowledge, this study provides the first estimate of US MHT prevalence-nearly 1 in 8 adults with nonelevated clinic BP-and suggests that millions of US adults may be misclassified as not having hypertension
Exploring a string-like landscape
We explore inflationary trajectories within randomly-generated
two-dimensional potentials, considered as a toy model of the string landscape.
Both the background and perturbation equations are solved numerically, the
latter using the two-field formalism of Peterson and Tegmark which fully
incorporates the effect of isocurvature perturbations. Sufficient inflation is
a rare event, occurring for only roughly one in potentials. For models
generating sufficient inflation, we find that the majority of runs satisfy
current constraints from WMAP. The scalar spectral index is less than 1 in all
runs. The tensor-to-scalar ratio is below the current limit, while typically
large enough to be detected by next-generation CMB experiments and perhaps also
by Planck. In many cases the inflationary consistency equation is broken by the
effect of isocurvature modes.Comment: 24 pages with 8 figures incorporated, matches version accepted by
JCA
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Ambient and Microenvironmental Particles and Exhaled Nitric Oxide Before and After a Group Bus Trip
Objectives: Airborne particles have been linked to pulmonary oxidative stress and inflammation. Because these effects may be particularly great for traffic-related particles, we examined associations between particle exposures and exhaled nitric oxide (FENO) in a study of 44 senior citizens, which involved repeated trips aboard a diesel bus. Methods: Samples of FENO collected before and after the trips were regressed against microenvironmental and ambient particle concentrations using mixed models controlling for subject, day, trip, vitamins, collection device, mold, pollen, room air nitric oxide, apparent temperature, and time to analysis. Although ambient concentrations were collected at a fixed location, continuous group-level personal samples characterized microenvironmental exposures throughout facility and trip periods. Results: In pre-trip samples, both microenvironmental and ambient exposures to fine particles were positively associated with FENO. For example, an interquartile increase of 4 μg/m3 in the daily microenvironmental PM2.5 concentration was associated with a 13% [95% confidence interval (CI), 2–24%) increase in FENO. After the trips, however, FENO concentrations were associated pre-dominantly with microenvironmental exposures, with significant associations for concentrations measured throughout the whole day. Associations with exposures during the trip also were strong and statistically significant with a 24% (95% CI, 15–34%) increase in FENO predicted per interquartile increase of 9 μg/m3 in PM2.5. Although pre-trip findings were generally robust, our post-trip findings were sensitive to several influential days. Conclusions: Fine particle exposures resulted in increased levels of FENO in elderly adults, suggestive of increased airway inflammation. These associations were best assessed by microenvironmental exposure measurements during periods of high personal particle exposures
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