|
| |
| -
2008 - |
| Jan.
10 |
No
TeleSeminar |
| Jan. 24 |
Host: Ara
Philipossian, Chemical and Environmental Engineering, University of Arizona
Presentations by: Yasa Sampurno and Xiaomin Wei, Chemical
and Environmental Engineering, University of Arizona
Topic titles:
1. Yasa Sampurno: "Applications of
Shear Force Spectral Analysis in STI CMP"
2. Xiaomin Wei: "Tribological, Kinetic,
Thermal and Flow Characteristics of PPS and PEEK Retaining Rings"
Abstracts:
1. Sampurno: This study explores the transition of shear force
spectral fingerprint during STI CMP using an APD-500 polisher capable of
simultaneously measuring real-time shear force and down force at high
frequencies. Fast Fourier Transformation is performed to convert the shear
force data from time domain to frequency domain and to illustrate the
amplitude distribution of the shear force. Such frequency spectra give
in-depth insight into interactions among abrasive particles, the pad and the
wafer. First, the effect of different ceria particle size on coefficient of
friction (COF) and removal rate is studied using 200-mm blanket PETEOS
wafers. COF and removal rate are found to both increase with particle size,
with saturation observed at the largest particle size studied. Secondly, STI
patterned wafers are over-polished using one of the above cerium oxide
slurries. Results show that shear force increases during polishing when the
HDP oxide layer is removed thus exposing the Si3N4 layer. At the same time,
variance of shear force is reduced. Unique and consistent spectral
fingerprints are generated showing significant changes in several
fundamental peaks before, during, and after transition to silicon nitride
polishing. It is believed that such spectral fingerprinting can be used to
monitor the STI polishing process in real-time. [Y. Sampurno 1; F. Sudargho
1,2; Y. Zhuang 1,2; T. Ashizawa 3; H.Morishima 3; and A. Philipossian 1,2 :
1 - Dept. of Chemical and Env. Engineering, University of Arizona,
Tucson, Arizona, USA; 2 - Araca, Inc., Tucson, Arizona,
USA; 3 - Hitachi Chemical Co., Ltd., Tokyo, Japan]
2. Wei: Retaining rings, with two designs, made of
polyphenylene sulfide (PPS) and polyetheretherketone (PEEK), were subjected
to wear tests to quantify their tribological, kinetic, thermal and flow
characteristics. White light interferometry was used to precisely measure
local wear rates. Additionally, a series of data including shear force, down
force, coefficient of friction (COF) and pad surface temperature were
captured in-situ using an Araca APD - 500 polisher. The PEEK rings were also
subjected to residence time distribution (RTD) tests at various pressures,
slurry flow rates and sliding velocities. Based on the open-system reactor
design theory, the mean residence time (MRT) was extracted from the
corresponding coefficient of friction (COF) vs. polish time curves
[X. Wei
1; A. Philipossian 1,2; Y. Sampurno 1; F. Sudargho 1,2; Y. Zhuang 1,2; C.
Wargo 3; and L. Borucki 2 : 1 - Dept. of Chemical and Env. Engineering,
University of Arizona, Tucson, Arizona, USA; 2 - Araca,
Inc., Tucson, Arizona, USA; 3 - Entegris Corporation, Billerica, MA 01821
USA].
(1-Sampurno:
PDF;
2-Wei:
PDF) |
| Feb. 7 |
Hosts: Krishna
Saraswat and Paul McIntyre, Stanford University
Presentation by: Andrew Kummel, University of
California-San Diego
Topic Title: "Scanning-Tunneling Microscopy and
Spectroscopy of Oxide Deposition on III-V"
Abstract: The correlation between the atomic bonding
structure and the electronic structure at oxide-semiconductor interfaces is
critical to understanding how atomic scale changes in electronic structure
can cause localization of electrons or holes at these interfaces. All logic
devices function by having an electric field perturb the electronic
structure of a semiconductor to change its resistance thereby activating the
device. The key material in this process is the interface between the gate
oxide and the semiconductor. Any fixed charge or defects which trap
electrons or holes destroy the device operation because the electric field
will be terminated by interface charges instead of being transmitted into
the semiconductor where the electrons or holes are conducted. We have used
atomically resolved scanning tunneling microscopy (STM) images and scanning
tunneling spectra (STS) to determine the atomic and electronic structure at
the gate-oxide semiconductor interface. Our research focuses upon the group
III-V semiconductors (GaAs, InGaAs, InAs) since they offer electron speeds
up to 30x greater than silicon as well as germanium since it offers 3x
higher hole speeds than silicon. In general, electronically passive
interfaces are formed when oxide deposition does not disrupt the
semiconductor lattice but instead restores the semiconductor surface atoms
back to more bulk-like electronic structure. Even in the absence of a
lattice disruption, oxide deposition can create new states in the bandgap
thereby pinning the Fermi level by two mechanisms: direct (the adsorbate
induced states in the bandgap region) and/or indirect (generation of
undimerized surface atoms). Insight into the atomic structure at the buried
interface has also been obtained by performing density function molecular
dynamics calculations to simulate the oxide/semiconductor interface.
(PDF) |
| Feb.
21 |
No
TeleSeminar
February 28th-29th: 12th Annual ERC Review Meeting, Tucson AZ |
| March
6 |
No
TeleSeminar |
| March 20 |
Host: Farhang
Shadman, Chemical & Environmental Engineering, University of Arizona
Presentation by: Carl Geisert, Sr. Principal Engineer,
FMS Manufacturing, Intel Corporation and Junpin Yao,
Ph.D. Candidate, Chemical &
Environmental Engineering, University of Arizona
Topic title: "Lowering Material and Energy Usage during
Dry-down of Ultra-pure Gas
Delivery Systems"
Abstract: Moisture is a
key impurity in ultra-pure gas delivery systems. During the system start-up
and the cleaning of systems that have been contaminated during operation,
very large amount of UHP gases and long purging time are required to clean
the above systems. This research systematically studied the fundamental
interaction mechanisms between moisture molecules and various surfaces and
components widely used in a typical gas delivery system. Using a
combination of a unique experimental method and a process model, a
methodology is developed to predict moisture removal and distribution in
main gas delivery lines and in lateral tool supply lines. Methods are
developed to optimize purge conditions to reduce purge time and cost. This
approach is also used to evaluate the adverse effects of dead legs (stagnant
regions) in UHP systems, and to figure out the minimum/critical flow rate
needed to block back- diffusion from tools and open ports. During a
contamination process, the dead legs play as a moisture trapping reservoir
and are difficult to clean. The slow intrusion of moisture out of the dead
leg can contaminate the main gas stream. The results also show that the
minimum gas flow rate to block back diffusion from ambient or contaminated
zones depends on the geometry of the pipe, tolerance levels, and impurity
concentration of contamination source. Case studies using fab typical
operating conditions show that significant reduction of purging time and gas
usage can be achieved using the results of this work. For example, instead
of steady state purge with high gas flow rate and high purity gas, the purge
process can be optimized by ramping purge gas purity and flow rate. In some
cases, it is also preferred to operate purging under low pressure if it is
allowable with actual situations. [Authors: Junpin Yao, Harpreet Juneja, Asad
Iqbal and Farhang Shadman, Chemical and Environmental Engineering,
University of Arizona; Carl Geisert, Intel Corporation] (PDF) |
| April 3 |
Host: Duane Boning,
Electrical
Engineering and Computer Science, Massachusetts Institute of Technology
Presentation by: Professor Tim G. Gutowski, Department of Mechanical
Engineering, Massachusetts Institute of Technology
Topic title: "Energy and Exergy Efficiency of
Manufacturing Processes"
Abstract:
In this talk
we look at general trends in manufacturing process energy and material
intensity. The talk includes a brief introduction to the exergy concept,
which serves as a framework for comparing processes. A very wide range of
process are considered including; conventional processes such as machining,
casting and injection molding, so called “advanced machining” processes such
as laser machining, electrical discharge machining and abrasive water jet,
as well as various semiconductor and nanotechnology vapor phase processes
such as Chemical Vapor Deposition, Plasma etching and thermal oxidative
treatment. The trends show that energy (and exergy) efficiencies have
decreased by eight orders of magnitude over the last several decades. The
talk closes with comments on the advantages and disadvantages of the exergy
measure. Many of the results found in the talk come from our 2007 and 2008
IEEE ISEE papers. (PDF) |
| April 17 |
Host: Srini Raghavan, Materials Science & Engineering, University of Arizona
Presentation by: Manish Keswani, Chemical &
Environmental Engineering, University of Arizona
Topic Title: "Megasonic Cleaning of Wafers in
Electrolyte Solutions: Possible Role of Electro-Acoustic and Cavitation
Effects"
Abstract: Megasonic cleaning is routinely used in the
semiconductor industry to remove
particulate contaminants from wafer and mask surfaces.
Cleaning is typically done in alkaline solutions with power density and
frequency of acoustic field being the key variables. Etching of films,
cavitation and acoustic streaming have been considered as the primary
cleaning mechanisms. Interestingly, our recent studies have shown that
near neutral solutions, without any etching of films, can indeed clean
wafers. One possible explanation for this cleaning effect relies on
electrical phenomena that accompany propagation of sound through
electrolyte solution.
The propagation of sound waves through an electrolyte solution
containing particles typically results in the generation of two types of
oscillating electric potentials, namely, Ionic Vibration Potential (IVP)
and Colloid Vibration Potential (CVP). These potentials and their
associated electric fields can exert forces on particles adhered to a
surface, resulting in their removal. In addition, the pressure amplitude
of the sound wave is also altered in solutions of higher ionic strengths,
which can affect the cavitation process and further aid in the removal of
particles from surfaces. Investigations have been conducted on the
feasibility of removal of particles from Si wafers in electrolyte
solutions of different ionic strengths irradiated with megasonic field of
different power densities. Cleaning experiments have been performed using
potassium chloride (KCl) as a model electrolyte and silica particles as
model contaminant particles. In order to characterize the cavitation
events in KCl solutions, acoustic pressure and sonoluminescence
measurements have been performed using hydrophone and cavitation probe
respectively. The results indicate that particle removal efficiency (PRE)
increases with KCl concentration and transducer power density and much
lower power densities are required at higher KCl concentration for a
comparable level of cleaning. Theoretical computations show that the
removal forces due to CVP are much larger in magnitude than those due to
IVP and are comparable to van der Waals adhesion forces. (PDF) |
| May 1 |
Host: Christopher Ober,
Materials Science & Engineering, Cornell University
Presentation by: Dr. Robert D. Allen, Manager of Lithography
and Water Filtration Materials, IBM Almaden Research Center
Topic Title: "Chemistry in the design of new resists and
other advanced patterning materials"
Abstract: Advanced lithography materials research is
important, challenging and incredibly interesting. At this time, immersion
lithography is beginning to impact volume manufacturing and already the
question of 'what's next' is really becoming urgent due to the long
development cycles and extreme expense of lithography technology. Many
potential future technologies have materials challenges at their core. Our
research program seeks to deeply understand materials implications of new
lithography technologies, hopefully to then design new materials that will
help enable future lithography, and to generate valuable IP in the process.
This program has produced strong commercial impact spanning many generations
of technology.
This talk will introduce our program at IBM Almaden Research Center, will
then discuss materials for immersion lithography, and finally will discuss
materials and concepts for future patterning. (PDF) |
| May 15 |
Host: Reyes Sierra,
Chemical & Environmental Engineering, University of Arizona
Presentation by: Laurie Beu, Consultant to ISMI/SEMATECH
Topic title: "ESH and ITRS Impacts on Semiconductor
Technology Development"
Abstract: Sustainable development had been defined as,
“Development that meets the needs of the present without compromising the
ability of future generations to meet their own needs.” While regulatory
compliance has been a major focus of many Environmental, Safety and Health (ESH)
programs, sustainable development is a concept that is beginning to impact
how semiconductor industry technologists design products and processes. In
2007 the International Technology Roadmap for Semiconductors (ITRS)
underwent a major revision and substantive changes were made to the ESH
Chapter. In addition to stressing business sustainability, four underlying
strategies are built into the ESH chapter:
- Understand
(characterize) processes and materials to create a development baseline;
- Use
materials that are less hazardous or whose byproducts are less hazardous;
- Design
products and systems (equipment and facilities) that consume less raw
material and resources; and
- Ensure
factories are safe for employees.
This seminar will review the
drivers for sustainable semiconductor manufacturing, and will provide an
overview of the 2007 ITRS ESH Chapter and its implications for semiconductor
technologists. (PDF) |
| May 29 |
Host:
Karen Gleason, Professor of Chemical Engineering and Associate Dean of
Engineering for Research, Massachusetts Institute of Technology.
Presentation by:
Karen Gleason, Massachusetts Institute of Technology
Topic title: "Low
Environmental Impact Processing of Sub-50 nm Interconnect Structures"
Abstract: A novel method
for processing of sub-50 nm structures by using carbon nanotube (CNT) masks
and integrating quantum dots (QDs) on patterned polymer substrates has been
established. Poly(styrene-alt-maleic anhydride) (PSMa) was prepared by the
initiated chemical vapor deposition (iCVD ) method, an alternative to
spin-on deposition. The sub-50 nm PSMa polymer patterns were prepared by low
energy oxygen plasma etching by using CNTs as the masks. The water soluble,
amine-functionalized QDs underwent the nucleophilic acyl substitution
reaction with the PSMa containing anhydride functional groups. This
integration method for developing high performance QDs devices
on inexpensive, lightweight flexible substrate avoids energy intensive
fabrication of high purity silicon wafer. [Chia-Hua Lee, Wyatt
Tenhaeff, Karen K. Gleason,
Department of Chemical Engineering, Massachusetts Institute of Technology]
(PDF) |
| June 12 |
Host: Anthony
Muscat, Chemical & Environmental Engineering, University of Arizona
Presentation by: Clark Lantz, Department of Cell
Biology and Anatomy, University of Arizona
Topic title:
"Environmental Health and Nanomaterials: Development of exposure analysis,
toxicity tests, and predictive risk assessment methods"
Abstract: The ability to predict adverse safety and
health outcomes from exposure to new and existing nanoparticles is essential
for reducing potential negative effects. Development of tools that can
identify material properties that are associated with adverse effects prior
to their incorporation into widespread industry use will greatly reduce
their impact on safety and health. Our goal is to develop and validate an
analysis framework that will integrate data from exposure monitoring,
biological interaction studies and material chemical and physical
properties, resulting in risk prediction of safety and health outcomes based
on material properties. [R.
Clark Lantz, Paloma Beamer, Paul Blowers, Scott Boitano, Jefferey L.
Burgess, and
Pierre
Herckes, University of Arizona and Arizona State University]
Rationale: Mechanistic risk assessment models must be
available to proactively characterize nanomaterial behavior with respect to
human health through multiple exposure routes and pathways. To complete
these models we need to determine nanoparticles absorption capabilities
across various biological membranes (i.e., lungs, skin) and assess the
interactions of absorbed contaminants with physiological systems and
ultimately identify how adverse health effects may occur from this new class
of materials. In addition, it will be necessary to define and measure
exposure from inhalation, ingestion and/or skin absorption, with the most
common pathways of exposure being inhalation and dermal through air and
water. We will address and integrate the following four areas that are of
interest to the industry: definitions of nanoparticle dose metrics (Herckes);
hierarchical risk assessment methods (Beamer); nanoparticle-bio interaction
studies (Lantz, Boitano, Burgess, Beamer); and predictive materials modeling
and statistical data-mining (Blowers). This project will advance the
ability to predict adverse Environmental Safety and Health (ESH) effects of
nanoparticles by assembling and integrating an innovative interdisciplinary
team with cutting-edge laboratory, field and modeling skills. The team
includes researchers in cell biology, physiology, exposure assessment, in
silico modeling and risk assessment. Team members are from five
different Departments (Cell Biology; Physiology; Community, Environment and
Policy; Chemical and Environmental Engineering; Chemistry and Biochemistry)
at two Universities. (PDF)
(1) (2)
(3) |
| June 26 |
Host: James
Farrell, Chemical & Environmental Engineering, University of Arizona
Presentation by: James Baygents, Chemical & Environmental
Engineering, University of Arizona
Topic title: "Electrocoagulation and Water Sustainability:
Silica and Hardness Control"
Abstract:
Electrocoagulation as
a technology to treat and purify large volumes of water begins with 19th
Century British and French patents, issued in 1887 for a wastewater
treatment method that, today, would be termed electrocoagulation (EC). The
first reported use of EC occurred in 1889 at a London water treatment plant
predicated on these 1887 patents. The first US patent on EC dates back to
1906. By the mid-20th Century, EC fell out of favor as a
large-scale (e.g. municipal) water-treatment technology owing to what were,
then, high operating costs and the availability of bulk chemical coagulants.
More recently, EC has attracted renewed interest, especially in the context
of specialized industrial water treatment applications. Several technical
reviews of EC cover its broad spectrum of uses, which include: metal ion
removal; semiconductor CMP waste treatment; phosphate removal; and the
removal of organic compounds and species. In the semi-arid southwestern
United States, EC has potential applications as a pre-treatment and
post-treatment for reverse osmosis (RO) water purification, as well as the
maintenance of water quality in cooling tower systems.
EC has several virtues as a water
treatment technology. First, conventional chemical coagulants, such as Al2(SO4)3
and FeCl3, involve the addition of anions along with the metal
cations that foster the coagulation processes. EC adds the desired
coagulating agent, e.g Al3+ or Fe2+, without adding
sulphate or chloride anions. EC is also very effective as a pre-treatment
for water with high turbidity or TDS that might otherwise shorten the life
of more expensive elements in a water treament train, such as ion-exchange
beads or RO membranes. Finally, EC units are relatively straightforward
and, in many contemporary applications, inexpensive to run, costing a few
dollars per thousand gallons.
There are
myriad bench-scale studies of EC that examine the effects of a long list of
operational parameters, including electrode voltage, electrode spacing and
surface area, reactor residence time, solution pH, etc. However, EC is
fundamentally a coagulation process, so it should come as no surprise that,
for a given contaminated stream, coagulant dose is the primary factor that
determines the extent to which a targeted compound is removed from
solution/suspension. In the work to be presented, we examine the use of EC
to remove dissolved silica and reduce water hardness (Ca2+ and Mg2+),
emphasizing the effect of coagulant dose. Data will be presented from a
series of bench and pilot scale studies on the use of continuous-flow EC to
treat two kinds of aqueous process streams, viz. cooling tower blowdown and
RO reject. These studies were carried out in collaboration with the Intel
Corporation facility in Ronler Acres, OR. The data show, at dosing levels
of 1 to 3mM coagulant (Fe or Al), 40 to 90% removal of dissolved silica (and
phosphate), accompanied by a 10 to 20% reduction of hardness minerals. When
operated with iron electrodes, removal of targeted compounds with the
6-gallon/min pilot unit was in remarkable agreement with that achieved in
the 1-liter/min bench-top device—demonstrating that the EC process scale-ups
up straightforwardly based on coagulant dose.
[James C. Baygents and James Farrell, Department
of Chemical and Environmental Engineering,
The University of Arizona] (PDF) |
| July 10 |
Host: Yoshio Nishi,
Electrical Engineering, Stanford University
Presentation by: Masaharu Kobayashi, Electrical Engineering,
Stanford University
Topic title: "Novel Contact Technology in Metal/Ge Schottky
Junction for Metal Source/Drain Ge NMOSFET Application"
Abstract: Non-silicon channel material, especially Ge, is one
of the key technology boosters to enhance device performance. There are
demonstrations of superior performance in Ge PMOSFETs to Si. Ge NMOSFETs
are, however, still not superior to Si. A major obstacle for Ge NMOSFETs is
the large source/drain (S/D) resistance due to poor dopant incorporation
into Ge. Although metal S/D is a possible candidate to reduce S/D
resistance, strong surface Fermi level pinning of Ge results in high
Schottky barrier height for electrons (FBNeff) with
typical germanides, such as NiGe, TiGe, CoGe. To mitigate this problem,
reduction of FBNeff is necessary to achieve low S/D
resistance in Ge NMOSFETs. In this paper, Fermi level depinning in metal/Ge
Schottky junction was experimentally and systematically investigated and it
is found that an ultrathin SiN successfully released Fermi level pinning and
achieved very low FBNeff. Ohmic transport was realized in
metal/n-Ge Schottky junction by the interfacial layer technique. Contact
resistance between different workfunction metal and n-Ge was exponentially
correlated with FBNeff,and FBNeff was
linearly modulated by changing metal workfunction with pinning factor 0.3,
which proved that Fermi level pinning was released and FBNeff
can be modulated by interfacial layer, not by the nature of bulk Ge.
Finally, the metal S/D Ge NMOSFET with low S/D resistance and low leakage
current was successfully demonstrated. We also proposed high vinj
from a low WF metal source. This novel junction technology is feasibly
integrated with high-k/metal gate and 3D-IC technologies which require low
thermal budget process. (PDF) |
| July 24 |
Host: Duane
Boning, Electrical Engineering and Computer Science, Massachusetts Institute
of Technology
Presentation by: Vladimir Bulovic, Lab of Organic Optics
and Electronics, Massachusetts Institute of Technology
Topic Title: "Nanostructures in Green Optoelectronics"
Abstract: Nanoscale elements such as molecules,
polymers, and nanocrystal quantum dots can be assembled into large area
functional optoelectronic devices that surpass the performance of today's
state-of-the-art technologies. Advances in thin film processing of
nanostructured material sets and concomitant development of physical models
of nanostructured device operation are rapidly advancing this science and
engineering field. Nanostructured optoelectronics is making inroads into
"green" energy production technologies (such as photovoltaics and
thermolectrics) and broad-scale energy consuming technologies (such as
energy efficient lighting and low-power display applications). Projected
performance efficiencies and production scalability of select nanostructured
optoelectronics suggest their ubiquitous use in the near future. As an
example of a recent nanoscale technology evolution, the talk will highlight
advancements in use of molecules and colloidaly-synthesized quantum dots to
fabricate light emitting devices of high color quality and broadly
deployable photovoltaics. (PDF) |
| Aug. 7 |
Host: Ara
Philipossian, Chemical & Environmental Engineering, University of Arizona
Presentation by: Yun Zhuang, Research Associate,
Chemical & Environmental Engineering, University of Arizona
Topic title:
"Analyses of Diamond Disc Substrate Wear and Diamond Micro-Wear in Copper
Chemical Mechanical Planarization Process"
Abstract: Diamond disc substrate wear and diamond micro-wear
in copper chemical mechanical planarization process were investigated in
this study. Three types of diamond discs (D1, D2, and D3) made by different
manufacturers were analyzed. For each type of diamond disc, 24-hour static
etch tests were performed with Cabot Microelectronics Corporation iCue
600Y75 and Fujimi PL-7103 slurries at 25 and 50 °C. SEM analysis was
performed on the diamond disc substrate and individual diamonds before and
after the static etch tests. In addition, ICPMS analysis was performed
before and after the static etch tests to investigate the metal
concentration changes in the slurry. The SEM analysis shows no appreciable
wear on the individual diamonds for all three types of diamond discs with
both slurries at 25 and 50 °C. The SEM analysis also shows no appreciable
wear on the diamond disc substrate for Disc D1 and Disc D3 with both
slurries at 25 and 50 °C. On the other hand, the SEM analysis shows apparent
surface corrosion for Disc D2 with Cabot Microelectronics Corporation iCue
600Y75 slurry at 50 °C and with Fujimi PL-7103 slurry at both 25 and 50 °C.
The ICPMS analysis shows with Fujimi PL-7103 slurry, the Ni concentration in
the slurry increases appreciably at 25 and 50 ºC for Disc D1; the Ni
concentration in the slurry increases significantly at 25 ºC and increases
dramatically at 50 ºC for Disc D2. With Cabot Microelectronics Corporation
iCue 600Y75 slurry, the ICPMS analysis indicates that the Ni concentration
in the slurry increases appreciably at 25 and 50 ºC for Disc D1; the Ni
concentration in the slurry increases appreciably at 25 ºC and increases
dramatically at 50 ºC for Disc D2, resulting in an extremely high activation
energy for Ni corrosion. In comparison, the ICPMS analysis indicates that
for both slurries, there is barely any increase in the Ni concentration in
the slurry at 25 and 50 ºC for Disc D3. In addition to the above static etch
tests, 24-hour wear tests were performed with both slurries for each type of
diamond disc on Araca’s APD-800 polisher at 25 and 50 °C. SEM analysis was
performed on the diamond disc substrate as well as on two selected
aggressive diamonds and one selected inactive diamond before and after the
wear tests. The SEM analysis indicates there is no appreciable wear on the
diamond disc substrate for Disc D1 and Disc D3, but there are apparent
surface corrosion and cracks formed on the disc substrate for Disc D2 with
both slurries at 25 and 50 °C. The SEM analysis shows there is no
appreciable wear on the inactive diamond but appreciable wear on the cutting
edges of aggressive diamonds for all three types of diamond discs. In
addition, the SEM analysis shows an aggressive diamond breaks from the
diamond disc substrate with Fujimi PL-7103 slurry at 50 ºC for Disc D2.
During the above static etch and wear tests, white light interferometric
analysis was performed on a 4 x 4 mm2 area as well as individual
aggressive diamonds to quantify diamond disc substrate wear and diamond
micro-wear. Diamond disc surface (including disc substrate and embedded
diamonds) height probability density functions were established through the
interferometric analysis. However, as the white light interferometer does
not capture the cutting edges of individual diamonds and the boundaries
between embedded diamonds and disc substrate because
most diamonds have non-flat and irregular shapes,
it is concluded that the interferometric analysis can not quantify diamond
disc substrate wear and diamond micro-wear accurately. Currently, confocal
microscopic analysis, which provides better images of diamond disc substrate
and individual diamonds, is being performed to enable quantitative
characterization of diamond disc substrate wear and diamond micro-wear. The
pad thickness profile was measured by micrometry after the wear tests. The
pad wear rate analysis indicates that for both slurries at 25 ºC, Disc D1
generates the highest pad wear rate while Disc D3 generates the lowest pad
wear rate. On the other hand, Disc D2 generates the highest pad wear rate
while Disc D3 generates the lowest pad wear rate for both slurries at 50 ºC.
For both slurries, the pad wear rate decreases with the increase of the
platen temperature for Disc D1 and Disc D3. On the other hand, the pad wear
rate increases with the platen temperature for Disc D2 for both slurries.
For all three types of discs, the pad wear rate for Fujmi PL-7103 slurry is
significantly higher than Cabot Microelectronics Corporation iCue 600Y75
slurry
indicating slurry abrasives and abrasive
concentration have significant impacts on the pad wear rate. (PDF) |
| Aug. 21 |
Host: Anthony
Muscat, Chemical & Environmental Engineering, University of Arizona
Presentation by: Professor Megan McEvoy, Biochemistry
Department, University of Arizona
Topic title: "Biologically Inspired Nano-Manufacturing"
Abstract: We are exploring the use of a novel additive
(bottom-up) process using biologically-active metal transport proteins to
grow three-dimensional arrays of nano-structures over macroscopic areas on
semiconductor surfaces. This approach using metal transport proteins could
be used to build nano-structures with lateral length scales below 20 nm.
Current lithographic techniques use hundreds of process steps and large
volumes of chemicals, energy and water creating significant amounts of
waste. Biological systems are many orders of magnitude more efficient in
energy and material usage. The research objective is to mimic the
techniques that nature uses in biological systems for reproduction,
selective deposition, patterning, fluid separation and purification.
Transporter proteins isolated from E.coli bacterial cells will serve as
uniform and reproducible "pores" of a very small diameter. The metal
transporters, embedded in a lipid membrane, actively pump metal ions against
a concentration gradient utilizing the energy from ATP hydrolysis.
Considered as fabrication process components, metal transporter systems show
high selectivity to metals, reproducibility, efficiency, narrow pore size
(<2nm), and activity under mild reaction conditions. In the present study we
have focused on the 80 kDa Cu(II) transporting ATPase CopB, from a
thermophilic organism, Archaeoglobus fulgidus, as a model metal transporter.
(PDF) |
| Sept. 4 |
Host: Jim Watkins,
Professor of Polymer Science and Engineering,
Director of NSF Center for Hierarchical Manufacturing, Co-Director of
MassNanoTech, Polymer Science and Engineering Department, University of Massachusetts
Presentation by:
Dr. Cengiz S. Ozkan,
Associate Professor of Mechanical Engineering, Co-faculty of Electrical
Engineering and the Materials Science and Engineering Program,
University of
California, Riverside
Topic title:
"Directed Assembly of
Nanostructures for Nanoelectronics"
Abstract:
The ITRS
(International Technology Roadmap for Semiconductors) anticipates that the
scaling of CMOS (complementary-metal-oxide-semiconductor) technologies may
end with 22 nm pitch length (9 nm physical gate length) by 2016. The ability
to scale within the last several decades has fueled multiple industries
ranging from high speed electronics to storage applications, and has led to
new and improved defense and industrial products. The development of
nanopatterning techniques including self and directed assembly are key for
enabling such innovations, which demand the patterning of nanostructures
with ever-smaller features in the 1-100 nm range. Bottom-up approaches for
fabricating nanodevices using nucleic acid sequences and viral templates
will be described. Understanding the mechanism of charge transport across
the bio-inorganic interfaces could result in the development unconventional
and revolutionary nanodevices. Electrical characterization of DNA assembled
nanoarchitectures demonstrate negative differential resistance which
indicates a route to fabricating molecular resonant tunneling diodes. A
novel memory effect was discovered for viral nanoarchitectures, based on
formation of bistable states. Such studies illustrate the great promise of
nanoengineering of functional materials and systems, and indicate new
avenues of technology and industry development which will have an impact in
our society as “the next industrial revolution”. (PDF) |
| Sept. 18 |
Host: Ara
Philipossian, University of Arizona
Presentation by:
Professor Rob White, Mechanical Engineering, Tufts University
Topic title: "In Situ Characterization of the Mechanical
Aspects of CMP"
Abstract: The objective of this project is to acquire in
situ data during chemical mechanical planarization (CMP) including slurry
flow patterns and flow velocity, wafer-pad contact percentages, wafer-scale
friction, and small-scale force measurements. The principle experimental
platform used is a heavily instrumented Struers RotoPol-31 table top
polisher. Measurements are taken for a variety of downforces (0.3-2.5 psi),
pad-wafer relative velocities (0-1.0 m/s), pad grooving (flat, XY grooved,
and AC grooved), and slurry injection points. Slurry flow patterns and
slurry velocities are measured in situ using flow tracers. Both qualitative
(flow visualization) and quantitative (particle image velocimetry) data have
been gathered. Dual Emission Laser Induced Fluorescence (DELIF) has been
employed to measure slurry thickness and pad-wafer contact percentage in
situ. Slurry thickness are on the order of 0-60 ìm, and mean measured
contact percentage was less than 1%. A combination of force and laser
sensors have been used for synchronous, in situ measurements of COF and
wafer orientation. Average COF values ranged from 0.45 to 0.57 and we find
the wafer pitches nose up relative to the rotating polishing pad by up to
0.65 degrees. Micromachined force sensors have been eveloped for use in
characterizing local, in situ shear forces. The sensors show polishing
forces to be highly variable in time with magnitudes between 0 and 300
micronewtons and time scales on the order of milliseconds. (PDF) |
| Oct. 2 |
Host: Alan West,
Department of Chemical Engineering, Columbia University
Presented by: Kristin G. Shattuck, Department of Chemical
Engineering, Columbia University
Topic title: Characterization of Phosphate Electrolytes for
use in Cu Electrochemical Mechanical Planarization
Abstract: Due to the introduction of fragile low-k
dielectrics, there is a need to modify current techniques used during
planarization to avoid dielectric degradation. Because of this, one of the
most important factors to consider is the downforce required to
achieve planarization. Currently, there are chemical mechanical
planarization (CMP) processes being developed that can provide polishing at
low downforces however, electrochemical mechanical planarization (ECMP) could
offer additional upgrades to current techniques. ECMP can not only operate
at low downforces (<1.0 psi), without slurry particles or oxidizers, but it
can also be tailored to achieve specific dissolution rates via applied
potential and, through the use of inhibitors, potentially achieve high
levels of planarization. Through the modification of a phosphate based
electrolyte, by the use of benzotriazole (BTA), a possible ECMP electrolyte
was developed. A broad range of electrolyte characteristics were screened
by utilizing a rotating disk electrode (RDE). The most important
parameters investigated were pH, salt concentration, and BTA
concentration. Results from the RDE were compared with results achieved
using both blanket and patterned wafer samples on a custom built ECMP tool.
A recommended electrolyte composition will be presented as well as a means
to predict planarization capabilities of electrolytes through the use of a
hypothetical planarization factor. (PDF) |
| Oct. 16 |
Host: Farhang
Shadman, Chemical and Environmental Engineering, University of Arizona
Presentation by: Jun Yan, Research Scientist, Chemical &
Environmental Engineering, and Kedar Dhane, Ph.D. Candidate, Chemical &
Environmental Engineering, University of Arizona
Topic title: "Fundamental Characterization of the Dynamics of
Rinsing, Cleaning, and Drying of Patterned Wafers and Nano-Structure"
Abstract: Rinsing and cleaning of patterned wafers are
complex processes that involve multiple mechanisms including bulk fluid
transport, molecular transport, and interface as well as surface
interactions. These fundamental process steps are poorly understood and the
process recipes are typically developed and controlled empirically and
rarely through fundamental process analysis and optimization. The key
shortcoming is the lack of reliable in-situ and robust metrology tools and
technology. To overcome this technology gap, an electrochemical residue
sensor (ECRS) is developed which is the first sensor technology with the
capability of in-situ and real-time monitoring the residual contaminants
inside trenches and vias of patterned structures. ECRS has high sensitivity
(down to ppt range) and can be used for both process characterization and
process control. The results show promising prospects of the applications
of the ECRS for various surface preparation steps. The experimental results
obtained by ECRS application are used to develop process models for rinsing
and drying; these models will be presented and discussed. (PDF) |
| Oct. 30 |
Host: Chris Ober,
Materials Science & Engineering, Cornell University
Presentation by: Abhinav Rastogi, Cornell
University and Gregory N. Toepperwein, University of Wisconsin
Topic title: "Environmentally Benign Development of Standard
Photoresists in Supercritical Carbon Dioxide"
Abstract: Environmentally benign supercritical
carbon dioxide (scCO2) has been utilized as an “ecological”
solvent for a wide variety of applications including the enhancement of the
processing performance in photolithography, especially in the development
step. However, non-polar scCO2 is generally a very poor solvent
for high molecular weight standard polymer photoresists. A series of
additives, quaternary ammonium salts (QAS), have been designed and
synthesized. The ability of these salts to assist in the dissolution of
resist materials was studied and compared using an ESCAP type, 193 nm,
poly(hydroxystyrene) based model photoresists. In parallel to the
experimental work, we carried out computational simulations to gain better
insight into the mechanism of the solubility switch of resists in the
presence of our salts. Our experimental and computational work will be
presented. We will also present the lithographic evaluation of a standard
polymer photoresist in
scCO2. (PDF) |
| Nov. 13 |
Host:
Reyes Sierra, Associate Professor, Department of Chemical & Environmental
Engineering, University of Arizona
Presentation by: Reyes Sierra, Chemical & Environmental
Engineering, University of Arizona
Topic title: “ESH Assessment of Biocides and Chelators used
in the Semiconductor Manufacturing”
Abstract: Chelating agents and biocides (C/Bs) are important
components in aid chemistries used in a wide variety of industrial
processes. This presentation will discuss the ESH characteristics of C/Bs
utilized in semiconductor manufacturing, particularly in wet cleans and
chemomechanical planarization operations. In addition, it will review the
fate of widely used C/B compounds during biological wastewater treatment as
well as their impact on aquatic life. (PDF) |
| Nov.
27 |
No
TeleSeminar - THANKSGIVING HOLIDAY |
| Dec. 11 |
Host: Karen
Gleason, Massachusetts Institute of Technology
Presentation by: Nathan J. Trujillo, Department of
Chemical Engineering, Massachusetts Institute of Technology
Topic title: "Depositing and
Patterning a Robust and “Dense” Low-k Polymer by iCVD"
Abstract: The new millennium has brought fourth many
technological innovations made possible by the advancement of high speed
integrated circuits. As the average feature size in integrated circuits
continues to decrease, reducing the dielectric constant of the interconnect
dielectric (ILD) becomes crucial to minimizing RC delay, power consumption
and cross talk noise. Common methods for reducing the dielectric constant
involve reducing the film density by incorporating void space and using
precursors with inherently open structures. Void space can be induced by
copolymerization of the low-k matrix with a thermally sensitive
porogen molecule, which is removed in a post-processing anneal. The
mechanical properties of SiCOH dielectrics generally decrease with lower
k values and typically scale with porosity as (1-p)3
until the percolation point, where pores coalesce. Therefore, there is a
need to improve the properties of the as-deposited “dense” films, before
porogens are incorporated. Initiated Chemical Vapor Deposition (iCVD) is a
low-energy, one step, solvent-free process for producing polymeric thin
films from one or more monomer species and an initiator species. iCVD is an
attractive technique for creating low-k films from cyclic siloxane
precursors. The low-energy process produces polymeric thin films that fully
retain the organic functionality of their monomer precursor. In this talk
we will discuss the deposition of a novel low-k iCVD precursor,
1,3,5,7-Tetravinyltetramethylcylcotetrasiloxane (V4D4). Dense films
are deposited at low substrate temperatures and are subsequently annealed in
air. The high degree of organic content in the as-deposited films affords
the ability to systematically tune the film properties by annealing. The
incorporation of atmospheric oxygen, at high temperatures, enhances the
mechanical and electrical properties of the films. These “dense” annealed
films provide favorable mechanical and electrical properties for
incorporating thermally sensitive porogen molecules. The structural
evolution of the films was characterized by FT-IR, XPS, and TGA/RGA, and the
mechanical, electronic, and optical properties were characterized by Nano-Indentation,
Hg-Probe, and VASE, respectively. Furthermore, using non conventional
lithography, we patterned the novel low dielectric constant polymer down to
25 nm, without the need for environmentally harmful solvents or expensive
lithography tools. (PDF) |
| Dec.
25 |
No TeleSeminar
- CHRISTMAS HOLIDAY |
|
