301 research outputs found
Design and implementation of a computational cluster for high performance design and modeling of integrated circuits
Modern microelectronic engineering fabrication involves hundreds of processing steps beginning with design, simulation and modeling. Tremendous data is acquired, managed and processed. Bringing together Information Technology (IT) into a functional system for microelectronic engineering is not a trivial task. Seamless integration of hardware and software is necessary. For this purpose, knowledge of design and fabrication of microelectronic devices and circuits is extremely important along with knowledge of current IT systems. This thesis will explain a design methodology for building and using a computer cluster running software used in the production of microelectronic circuits. The cluster will run a Linux operating system to support software from Silvaco and Cadence. It will discuss the selection, installation, and verification of hardware and software based on defined goals. The system will be tested via numerous methods to show proper operation, focusing on TCAD software from Silvaco and custom IC design software from Cadence. To date, the system has been successfully tested and performs well. Since the target applications are doing simulations that are independent of each other, parallelization is very easy and user friendly. By simply adding more computers with more CPUs, the maximum number of people and processes that can be supported scales linearly. With a staged approach and the selection of the right software for the job, the integration of IT components to build a computer cluster for microelectronic applications can be completed successfully
Incorporation of Control charts into a Manufacturing Execution System
The wafer fabrication facility at RIT has a primary goal of being a teaching facility. Tracking of the student run wafer lots is accomplished very effectively by MESA, a lot-tracking software package. The system is configured to collect information, but data base queries were not set up to display this information. MESA has the option of outputting information from the databases to a statistical software package called Quality Analyst. Quality Analyst displays control charts for the extracted data, providing quick, visual interpretation of the process in question. The adaptation of this software into the RIT Microelectronic Engineering fabrication facility has been achieved. Full realization of the impact on wafer yields has not been extracted so far, but insight into process improvement has already begun
Knudsen Diffusion in Silicon Nanochannels
Measurements on helium and argon gas flow through an array of parallel,
linear channels of 12 nm diameter and 200 micrometer length in a single
crystalline silicon membrane reveal a Knudsen diffusion type transport from
10^2 to 10^7 in Knudsen number Kn. The classic scaling prediction for the
transport diffusion coefficient on temperature and mass of diffusing
species,D_He ~ sqrt(T), is confirmed over a T range from 40 K to 300 K for He
and for the ratio of D_He/D_Ar ~ sqrt(m_Ar/m_He). Deviations of the channels
from a cylindrical form, resolved with transmission electron microscopy down to
subnanometer scales, quantitatively account for a reduced diffusivity as
compared to Knudsen diffusion in ideal tubular channels. The membrane
permeation experiments are described over 10 orders of magnitude in Kn,
encompassing the transition flow regime, by the unified flow model of Beskok
and Karniadakis.Comment: 4 pages, 3 figure
Imbibition in mesoporous silica: rheological concepts and experiments on water and a liquid crystal
We present, along with some fundamental concepts regarding imbibition of
liquids in porous hosts, an experimental, gravimetric study on the
capillarity-driven invasion dynamics of water and of the rod-like liquid
crystal octyloxycyanobiphenyl (8OCB) in networks of pores a few nanometers
across in monolithic silica glass (Vycor). We observe, in agreement with
theoretical predictions, square root of time invasion dynamics and a sticky
velocity boundary condition for both liquids investigated.
Temperature-dependent spontaneous imbibition experiments on 8OCB reveal the
existence of a paranematic phase due to the molecular alignment induced by the
pore walls even at temperatures well beyond the clearing point. The ever
present velocity gradient in the pores is likely to further enhance this
ordering phenomenon and prevent any layering in molecular stacks, eventually
resulting in a suppression of the smectic phase in favor of the nematic phase.Comment: 18 pages, 8 figure
Thermal Analyzer for Planetary Soil (TAPS): an in Situ Instrument for Mineral and Volatile-element Measurements
Thermal Analyzer for Planetary Soil (TAPS) offers a specific implementation for the generic thermal analyzer/evolved-gas analyzer (TA/EGA) function included in the Mars Environmental Survey (MESUR) strawman payload; applications to asteroids and comets are also possible. The baseline TAPS is a single-sample differential scanning calorimeter (DSC), backed by a capacitive-polymer humidity sensor, with an integrated sampling mechanism. After placement on a planetary surface, TAPS acquires 10-50 mg of soil or sediment and heats the sample from ambient temperature to 1000-1300 K. During heating, DSC data are taken for the solid and evolved gases are swept past the water sensor. Through ground based data analysis, multicomponent DSC data are deconvolved and correlated with the water release profile to quantitatively determine the types and relative proportions of volatile-bearing minerals such as clays and other hydrates, carbonates, and nitrates. The rapid-response humidity sensors also achieve quantitative analysis of total water. After conclusion of soil-analysis operations, the humidity sensors become available for meteorology. The baseline design fits within a circular-cylindrical volume less than 1000 cm(sup 3), occupies 1.2 kg mass, and consumes about 2 Whr of power per analysis. Enhanced designs would acquire and analyze multiple samples and employ additional microchemical sensors for analysis of CO2, SO2, NO(x), and other gaseous species. Atmospheric pumps are also being considered as alternatives to pressurized purge gas
Morphologic Parameters for Successful Lunar Landing Sites
The Moon, with its abundant resources, intriguing science questions, and vast unexplored surface area, is the most attainable and useful near-term target for future human exploration. In recognition of this fact, Presidential Space Policy Directive 1 (PSPD-1) has directed the United States to return to the Moon for long-term exploration and utilization, beginning with the 7th American human lunar landing by 2024 and building to sustainable surface presence by 2028
NASA Desert RATS 2011 Education Pilot Project and Classroom Activities
The National Aeronautics and Space Administration's (NASA's) Desert Research and Technology Studies (Desert RATS) is a multi-year series of tests of hardware and operations carried out annually in the high desert of Arizona, as an analog to future exploration activities beyond low Earth orbit [1]. For the past several years, these tests have occurred in the San Francisco Volcanic Field, north of Flagstaff. For the 2011 Desert RATS season, the Exploration Systems Mission Directorate (ESMD) at NASA headquarters provided support to develop an education pilot project that would include student activities to parallel the Desert RATS mission planning and exploration activities in the classroom, and educator training sessions. The development of the pilot project was a joint effort between the NASA Johnson Space Center (JSC) Astromaterials Research and Exploration Science (ARES) Directorate and the Aerospace Education Services Project (AESP), managed at Penn State University
Infrared study of the phonon modes in PrMnO and CaMnO
The infrared (IR) reflectivity spectra of orthorhombic manganese perovskites
PrMnO and CaMnO are studied in the frequency range of optical phonon
modes at temperatures varying from 300 to 4 K. The IR phonon spectra of these
two materials are analyzed by a fitting procedure based on a Lorentz model, and
assigned to definite vibrational modes of structures by comparison with
the results of lattice dynamical calculations. The calculations have been
performed in the framework of a shell model using short range
Born-Mayer-Buckingham and long range Coulomb potentials, whose parameters have
been optimized in order that the calculated Raman and IR active phonon
frequencies, and lattice parameters match with their experimental values. We
find a close correspondence between the values of the IR phonon frequencies of
PrMnO and CaMnO, which shows that the substitution of the Pr
ions with Ca results in a reduction of the frequency of medium- and
high-energy IR phonons, and an increase of the frequency of those of
low-energy. Nevertheless, the experimentally obtained IR phonon amplitudes of
the two materials appear to be unrelated. A comparative study of the
vibrational patterns of these modes reveals that most of them correspond to
complex atomic vibrations significantly different from PrMnO to CaMnO
which cannot be assigned only to a given type of vibration (external, bending,
or stretching modes). In particular, these results confirm that the structure
of CaMnO is quite far from the ideal (cubic) perovskite structure.Comment: 10 pages, 6 figure
Observation of charge-density-wave excitations in manganites
In the optical conductivity of four different manganites with commensurate
charge order (CO), strong peaks appear in the meV range below the ordering
temperature T_{CO}. They are similar to those reported for one-dimensional
charge density waves (CDW) and are assigned to pinned phasons. The peaks and
their overtones allow one to obtain, for La{1-n/8}Ca{n/8}$MnO{3} with n = 5, 6,
the electron-phonon coupling, the effective mass of the CO system, and its
contribution to the dielectric constant. These results support a description of
the CO in La-Ca manganites in terms of moderately weak-coupling and of the CDW
theory.Comment: To be published on Phys. Rev. Let
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