|
| |
| -
2005 - |
| Jan. 6 |
No
TeleSeminar -- Happy New Year |
| Jan. 13 |
Host: Farhang
Shadman, University of Arizona
Presentation by: Dr.
Andrew D. Maynard, Senior Service Fellow, National Institute for
Occupational Safety and Health (NIOSH)
Topic:
"Working with Engineered Nanomaterials: Towards Developing Safe Working
Practices"
Abstract:
Nanotechnology has been hailed as the next
technological revolution and is poised to impact on every aspect of our
lives. Through the manipulation of matter at near-atomic scales, the
technology is enabling remarkable progress in many fields to produce new
materials, structures and devices with unique and truly innovative
properties. Although predominantly at the laboratory and pre-commercial
stage, nanotechnology-based commercial products are already available,
ranging from cosmetics to stain-resistant clothing. The future promises
significant advances in areas as diverse as next-generation electronics,
high efficiency energy conversion and storage, novel sensors and advanced
medical diagnostics.
As with all new technologies, exploiting the unique behavior of
nanomaterials and devices also introduces the potential for unique and
unforeseen health impacts. Based on what limited data are available, the
environmental group ETC have called for a global moratorium on
nanotechnology, until more is known about the potential health effects.
More recently, a joint report of the United Kingdom Royal Society and Royal
Academy of Engineers strongly emphasized the need to address the potential
health impact of nanotechnology, particularly in the workplace. These
concerns are being echoed within research laboratories, industry, government
and even the insurance community. A key issue is whether currently accepted
models relating exposure to health effects are valid for engineered
nanomaterials: Current evidence would suggest that they are not.
The successful and responsible development of nanotechnology is dependent on
minimizing the health risk to workers and others, while maintaining public
confidence in the technology. This is a daunting task, and not one that can
be undertaken lightly or in isolation. A critical element is the
development of appropriate working procedures and strategies that reduce the
potential for harmful health impact. Although current information on
nanomaterial exposure, toxicity and control is sparse, we are in a position
to begin formulating appropriate ways of working with nanomaterials based on
the knowledge we do have at our disposal. This seminar will provide a broad
overview of practical considerations towards developing strategies to ensure
safe working practices. While acknowledging that all exposure routes may
have relevance, emphasis will be given to understanding and addressing
inhalation exposure. (PDF) |
| Jan. 20 |
Host: Karen Gleason,
MIT
Presentation by: Tom Casserly, Massachusetts Institute of
Technology
Topic:
"Effect
of Substrate Temperature for Plasma-Enhanced Chemical Vapor Deposition of
Poly(methylmethacrylate) as a Sacrificial Material for Air Gap Fabrication”
Abstract: As the push toward
smaller dimensions in semiconductor manufacturing continues the need for low
dielectric constant (k) materials becomes ever greater. Reducing the
dielectric constant of the material between metal lines in integrated
circuits not only decreases the resistance capacitance (RC) delay, but also
reduces power consumption, cross-talk noise and can allow for fewer levels
of interconnect. Air has the lowest dielectric constant, 1.0. In the
January 1, 2005 issue of Semiconductor International, Senior Editor
Laura Peters argues for air gaps as a low-k alternative needed at this
time. She argues that “Porous dielectrics have too many problems — at least
as many as their dense counterparts — and the overall benefit they deliver,
represented as the effective k value, may be small given the integration,
yield and reliability challenges they pose and the costs required to
surmount them.”
Poly(methylmethacrylate) (PMMA) is an excellent sacrificial material for use
in air gap fabrication. Low power plasma-enhanced chemical vapor deposition
(PECVD) of methylmethacrylate is a dry method for creating thin films with
properties and structure similar to that of PMMA. Both continuous wave
PECVD and pulsed-PECVD methods are examined for the deposition of PMMA.
FTIR and XPS confirm the structural similarity to bulk PMMA for both cases
when using the same average power. Increasing the substrate temperature
during deposition the solubility of the resulting polymer in water,
isopropyl alcohol and acetone can be reduced to zero. The onset of thermal
decomposition also increases with increasing substrate temperature. By
increasing the substrate temperature the presence of unstable oxygen bonds
in the backbone of the polymer common in free radical polymerization of PMMA
can be eliminated. This creates a more stable film requiring much higher
temperatures for the initial thermal decomposition to occur. The resulting
polymer has been patterned using conventional lithography, covered by layer
of organosilicate glass (OSG) and annealed to form air gap structures. (PDF) |
| Jan. 27 |
Host: Chris Ober,
Cornell University
Presentation by: Jim Jewett, Intel Corporation
Topic: "Perspectives on PFOS"
Abstract: This TeleSeminar
will be a contextual presentation on the issue with PFOS, including some
background (politics, regulatory development, etc.), a look at the
implications to chip manufacturing (where we use it, why it is important,
etc.), some generic technical coverage, and identification of areas for
potential University (ERC) research. (PDF) |
| Feb. 3 |
Host: IAB -
Dan Seif, Advanced Micro Devices Inc.
Presentation by: Kathleen H.
Peters, 3M Electronics Markets Materials Division, 3M Center 236-2B-01
Topic: "Reducing Emissions of
PFC Heat Transfer Fluids"
Abstract: PFCs were used during the 1950s in some defense
applications in the United States. The PFCs became widely used in the
semiconductor industry during the 1980s, mainly in etch, plasma vapor
deposition, ion implant and test processes. In an effort to reduce the PFC
emissions, a voluntary coalition of companies joined together and made a
Memorandum of Understanding (MOU) with the US EPA. In 1999, the World
Semiconductor Council (WSC) made a commitment to decrease the PFC
gaseous emissions by 10% below the 1995 baseline by 2010. Then, in
2001, the MOU was renewed with the US EPA, spurring widespread international
participation by several countries including Japan, Korea, China and Taiwan.
The efforts to decrease emissions from PFC gases was largely successful, due
to process optimization, abatement and investigation of alternative
chemistries. In this talk, two approaches to reducing emissions from PFC
liquids are addressed. The first approach is to implement system
optimization of onsite processes to identify leakage and minimize
evaporative losses. The second approach is to adopt alternative
chemistries. Segregated hydroflouroethers (HFEs) have a global warming
potential of 0.5-5% of those from PFC liquids. In addition, they are
non-flammable, non-corrosive, have zero ozone depletion, and are not
regulated in the US for toxicity. The use of HFEs requires little to
no equipment modification from systems currently set up for PFCs liquids.
(PDF) |
| Feb. 10 |
Host: Krishna
Saraswat, Stanford University
Presentation by: Kang-Il Seo, Senior PhD Student,
Materials Science and Engineering Department, Stanford University
Topic: Engineering of interfacial
layer between high-k (ZrO2, HfO2) and Semiconductor (Si, Ge)
Abstract: The continued scaling of Si complementary
metal-oxide-semiconductor (CMOS) devices has lead to a need to replace the
SiO2 gate insulator with high-k dielectric oxides, in order to maintain a
smaller leakage current without loosing gate control of the channel region.
Among many candidates, ZrO2, HfO2 and their alloys with SiO2 and Al2O3 have
attracted attention due to their high permittivity and thermodynamic
stability with respect to solid state reaction with the Si substrate.
Recently, these high-k dielectrics began to be studied on Ge channels to
take advantage of the high intrinsic electron mobility (2×) and hole
mobility (4×) of Ge, compared to that of Si. However, when high-k
materials are deposited on semiconductor, the interfacial layer inevitably
forms between high-k and semiconductor, and plays a crucial role in device
performance. Usually the interfacial layer has significantly lower
dielectric constant compared to the high-k film, which deteriorates the
benefit of high-k layer by decreasing overall capacitance. Also, observed
device performance degradations like mobility degradation in MOS device with
high-k dielectric have strongly suggested that the physical defects and
electrical traps in the interfacial layer are mainly responsible for those
problems. Recently, significant amount work has been focused to investigate
the physical and electrical nature of this interfacial layer.
In this presentation, we demonstrate our recent results to engineer
the interfacial layer between high-k (ZrO2, HfO2) and semiconductor ( Si
(001), Ge (001) ). First, we show that formation of a Zr-silicate
interfacial layer between ZrO2 and Si substrate can be controlled by the
solid state reaction between Zr and an underlying SiO2/Si substrate through
in-situ vacuum anneals and subsequent ultra-violet (UV) oxidation. In-situ
vacuum annealed samples containing the silicate interface layer exhibited
excellent dielectric characteristics, such as negligible capacitance-voltage
hysteresis (~ 10mV), lower fixed charge density, and reduced equivalent
oxide thickness (EOT) compared to un-annealed samples.
Next, we report the chemical bonding structure and valence band
alignment at the HfO2/Ge (001) interface by systematically probing various
core level spectra as well as valence band spectra using synchrotron soft
x-rays at beam line 8-1 of the Stanford Synchrotron Radiation Laboratory.
We found that a very thin GeOx layer of ~3Ã… thickness with highly non-stoichiometric
chemical nature exists at the HfO2/Ge interface. From the valence band
spectra near the Fermi level, the valence band offset between Ge and GeOx
was determined to be ΔEv (Ge-GeOx) = 2.2±0.15 eV, and between Ge and HfO2,
ΔEv (Ge-HfO2) = 2.7±0.15 eV. The implications of this highly non-stoichiometric
GeOx interfacial layer and the observed energy band alignment for electrical
properties such as C-V and I-V characteristics will be discussed.
(PDF) |
| Feb. 17 |
No TeleSeminar |
| Feb. 24 |
No TeleSeminar -- 9th
Annual ERC Site Review Meeting (February 24-25th in Tucson AZ) |
| March 3 |
No TeleSeminar |
| March 10 |
Host: Paul
McIntyre, Stanford University
Presenters: Raghav Sreenivasan and Jeong-hee Ha, Stanford
University
Topic:
Sreenivasan:
"Structure-Property Relations in ALD-Grown HfO2 Gate Dielectrics: Effects of
Precursor Chemistry"
Abstract: This presentation will
compare the physical structure, dielectric properties and carrier
trapping/conduction behavior of ALD-HfO2 gate dielectrics grown using HfCl4
and TDEAH (tetra-diethyl amido Hf) precursors. The alkylamide
precursor-grown samples exhibit superior charge trapping characteristics and
less stretch-out of the capacitance-voltage curve, indicating a lower
interface state density than chloride-grown ALD-HfO2. (PDF)
Topic:
Ha: "In Situ X-Ray
Scattering Measurements of Phase Separation at Initially-Intermixed
HfO2/SiO2 Interfaces"
Abstract: X-ray scattering is a
well-established ultra-sensitive probe of interdiffusion in multilayer thin
films. In this research, we used this technique to study a system that
exhibits a strong tendency for diffusional phase separation: amorphous
HfO2-SiO2 alloy layers. Sequential deposition and low temperature UV-ozone
oxidation of ultrathin Hf and Si films was used to prepare a HfO2/SiO2
multilayer. In situ annealing experiments in an x-ray diffractometer were
performed and the evolution of x-ray satellite peak intensity was used to
determine the kinetics of phase separation of the initially-intermixed
interfaces. (PDF) |
| March 17 |
Host: Jeff
Butterbaugh, FSI
International Inc.
Presentation by: Steve Nelson, Senior Applications Development Engineer, FSI
International Inc.
Topic: "Metrics and
Methods for Reducing Rinse Water Consumption in an Immersion System"
Abstract: Using measurements of oxide etch uniformity
and pH, both overflow rinsing and dump rinsing can be optimized. Optimized
rinsing is very important as wafers become larger in diameter and as the
spacing between wafers in a batch becomes closer. Poorly rinsed areas on a
wafer can be found by testing the oxide etch uniformity. Adjustments can
then be made to the rinsing hardware or nozzles to better rinse all areas of
the wafers. Measurement of the pH of the liquid in the bath or the resistivity
shows how quickly the chemical in removed from the tank. However, removing
the chemical from the surface of the wafers is more important. We have
developed a way to use pH measurements to determine the amount of chemical
near the wafer surface and have used this technique to further optimize
rinsing. After optimizing our rinse we achieved better process results in
less time and with less water consumption. (PDF) |
| March 24 |
Host: Jeff ,
STMicroelectronics Inc./University of Arizona
Presentation by: Dr. John Bare,
R&D
Program Director, psiloQuest
Topic: “Novel CMP Pad for Tungsten Polishing”
Abstract: psiloQuest has developed a CMP polishing pad which uses
material technology substantially different from conventional polyurethane
CMP pads. The polyolefin foam pad has a closed cell structure which does
not require diamond conditioning, has a long pad lifetime, consistent
performance, and exceptionally low defects. These properties combine to
produce a lower cost of ownership. There are additional environmental
benefits from reduced slurry usage and pad consumption. The material
capitalizes on the chemical contribution to CMP rather than mechanical
contribution. In the most developed formulation, the materials or
processes which can most benefit from more “C” than “M” include tungsten,
copper clear, and copper barrier clear. Polymer blend, foam density, and
filler concentration can be independently varied to change foam cell size,
thermal stability, hardness, and resilience. Oxidizer levels in the
slurry can be adjusted for specific applications to maximize performance
for the individual user’s most important criteria, such as removal rate or
erosion. (PDF) |
| March 31 |
Host: Farhang
Shadman, University of Arizona
Presentation by: Jost
Wendt, Professor and Head, Department of Chemical and Environmental Engineering, University
of Arizona
Topic: "High
Temperature Generation, Sampling, and Analysis of Inorganic Nano-Particles
and Their Health Effects"
Abstract: High temperature flame reactors were used to
explore mechanisms governing the temporal evolution of particle size
distributions of both non-volatile, and semi-volatile metals, as they pass
from temperatures exceeding 2000K to the exhaust at 600K. Of interest were
Cr, Ni, Zn, Pb and Cd, which were introduced either as aqueous solutions
sprayed through a gas flame, or as a distillate oil doped with organo-metallic
compounds, which were subsequently burned. When nucleation of the metal
vapor predominates over condensation on existing surfaces, ultra-fine nano-particles
are formed.
Modes of behavior of both single metals and binary
mixtures of lead and cadmium (where nucleation of metal vapors predominated)
and of cadmium and nickel (where condensation of cadmium vapor upon larger
nickel particles predominated) were investigated. Particulate samples were
withdrawn iso-kinetically through a rapid-dilution sampling probe from which
they were quickly size segregated in a Berner, low pressure, impactor,
allowing physical and chemical resolution in the submicron particle size
range. The effects of sampling parameters on possible distortions in the
measured particle size distributions were explored both theoretically and
experimentally. Many semi-volatile metals can be also be reactively
sequestered in flight, by dispersed alumino-silicate powders. The extent of
sequestration can be determined by, the method of aerosol fractionation,
which is described in detail.
Health effects of inhaled particles containing zinc
were investigated. Here particles were sampled and re-suspended for whole
animal inhalation studies. The re-suspension device was characterized in
detail. It was shown that lung injury was more likely in the presence of
sulfur than in its absence, even though ultra-fine particles were formed in
both cases. Lung injury in mice could be mitigated by employing alumino-silicate
sorbents to reactively sequester the zinc before it condensed. (PDF) |
| April 7 |
Host: Paul Blowers,
University of Arizona
Presentation by: Umur Yanal, University of Arizona
Topic: "Water
Treatment Optimization in a Basin Model for Water Resources Simulation"
Abstract: Available water supplies are already stressed
in arid regions in general and the Southwestern US in particular. This
coupled with rapid growth and an increasing demand for high quality water in
these same areas. The water quality of the available sources often is not
enough to meet the required level. To relieve the water shortfalls,
alternative measures, such as agricultural land retirement, water transfers,
and water reuse/reclamation are being studied. However, there is a lack of
comprehensive tools for analyzing the effects of alternative scenarios on
water quantity, quality and cost.
The overall aim of this large project is to develop a
comprehensive decision-support model for technical and non-technical
audiences concerned with understanding and evaluating the impact of
alternative water management options. The particular aim of this research
work is to develop the water and wastewater treatment components for
incorporation into a large regional model.
Water quality is the key parameter for water use. The
required water quality depends on the type of user. The quality requirements
of the consumers show a wide range of diversity. Hence, the connection of
users to sources is often contingent on satisfactory and affordable
treatment. Traditionally, water treatment has been centralized at large
water treatment plants prior to general distribution and subsequently at
large wastewater treatment plants after manifolded collection of the many
users’ discharges. This centralized approach is often far from optimum as it
ignores economic matching of water users’ specific quality and quantity
needs with proximated discharges that may immediately meet, or with modest
treatment meet, the users' requirements. The optimization of selection,
size, and placement of water and wastewater treatment plants will reduce
overall costs and help to produce potential new water resources. Up to now,
no general water balance model with the water quality as a modeled parameter
exists.
Initial model development requires selection of a
limited set of water quality parameters for consideration that are
representative of the main classes of contaminants of interest. Total
dissolved and suspended solids, total organic carbon, biochemical oxygen
demand, hardness, total nitrogen, total phosphorus, total coliform were
first chosen. Furthermore, some specific compounds, e.g. bisphenol A,
dieldrin, b-estradiol, arsenic,
lead, and mercury were chosen to be representatives of the significant trace
pollutants important in the environment.
The optimization of the water and wastewater treatment
plants is planned considering the cost as well as the removal efficiencies.
So far, contaminant adsorption and the particulate matter sedimentation are
modeled by granular activated carbon (GAC) and primary sedimentation basin,
respectively. Optimization of further unit operations is projected to be
completed by the end of April 2005. (PDF) |
| April 14 |
Host: Reyes Sierra,
University of Arizona
Presentation by: Dr. Jack R. Geibig, Acting Director, University of Tennessee
Center for Clean Products and Clean Technologies
Topic:
"Life-Cycle Impacts of Lead and Lead-Free Solder Used in Wave Soldering of
Electronics"
Abstract: Results from a joint
US EPA and US electronics industry-funded life-cycle assessment of lead and
two lead-free alternative solders are presented. Solders evaluated in the
study include:
- SnPb (paste and bar)
- SnAgCu (paste and
bar)
- SnAgBiCu (paste)
- BiAgCu (paste)
- SnCu (bar)
Impact scores are
reported in 16 different environmental categories for both wave and reflow
soldering applications. Tin-lead solder was determined to have higher impact
scores than the lead-free solders in four categories, while having lower
impacts in five. The use/application stage was the dominant contributor to
most impact categories, while upstream and end-of-life processes also made
significant contributions to specific impact categories, depending on the
solder. Sensitivity analyses of the effect of silver production as well as
landfill leachate data are also presented. (PDF) |
| April 21 |
Host: Anthony Muscat,
University of Arizona
Presentation by: Sarah Perry, University of Arizona
Topic: “Preparation of High Quality Si/SiO2
Interfaces After Extended Exposure to Ambient Contamination Using Gas Phase
Methoxy Passivation”
Abstract: Organic
surface passivation of silicon has been shown to protect against oxidation
and contamination better than the hydrogen termination resulting from
aqueous etching chemistries. This development has the potential to improve
semiconductor device yield, interface quality, and to decrease chemical
usage and process bottlenecking for pre-deposition cleaning. Interface
quality between the device layers, particularly for the Si/SiO2
gate region, has become increasingly critical with shrinking device
dimensions. X-ray photoelectron spectroscopy (XPS) measurements were used
to characterize two gas phase reactions; the direct adsorption of methanol
on hydrogen terminated silicon, and a two step iodination/methanol reaction.
Methoxy termination of silicon surfaces (CH3O-Si) protected
better against oxidation and adventitious carbon contamination than a
hydrogen terminated surface prepared using standard aqueous phase
chemistries. The organic functionality desorbed cleanly from the surface
upon heating, requiring no additional removal step before thermal
oxidation. Capacitance-voltage (C-V) electrical measurements
demonstrated that the use of methoxy passivation does not adversely affect
the Si/SiO2 interface trap density. The highest quality
interface was achieved after exposure to ambient conditions over time by
passivation using a two-step UV-iodine/methanol treatment. (PDF) |
| April 28 |
Host: Yoshio Nishi,
Stanford University
Presentation by: Dr. Ken Uchida, Visiting Scientist at Stanford
University, on leave from Toshiba Corporation-R&D
Topic: "Challenge and Opportunities of Future Nanoelectronic
Devices"
Abstract: Scaling down of electronic device sizes
has been the fundamental strategy for improving the performance of ULSIs.
MOSFETs have been the most prevalent electron devices for ULSI applications,
and thus the scaling down of the sizes of MOSFETs has been the basis of the
development of the semiconductor industry for the last 30 years. In recent
years, the scaling of CMOSFETs is entering the deep sub-50 nm regime. In
this deep-nanoscaled regime, however, fundamental limits of CMOSFETs and
technological challenges respecting the scaling of CMOSFETs are encountered.
In this presentation, the technologies to overcome
these obstacles will be discussed. The technologies include Ultrathin-body
SOI and Schottky Source/Drain MOSFETs. In addition, single-electron devices
for logic and security applications will be discussed.
(PDF) |
| May 5 |
Host: Stephen Beaudoin, Purdue University
Presentation by: Richard Freeman, Managing Director, Zeeko
Technologies Ltd.
Topic:
“Polishing of Microelectronic Thin Films Using a Corrective Polishing
Technique Developed for the Optics Industry”
Abstract: This talk reports on a new machine
development that may have great relevance to the semiconductor industry.
The Zeeko polishing process has been developed for the figuring and
corrective polishing (the polishing out of an error map) of high precision
optics with values of Ra~2nm routine in an industrial environment. Thus the
Zeeko process enables the controlled polishing of thin layers, removing
small amounts of material to create a uniform thickness that can follow the
form of the underlying substrate. While it is a young process, it has
already been used in laboratory testing in conjunction with traditional CMP.
The combined process demonstrated that CMP removes material rapidly, but in
a relatively uncontrolled manner, and the Zeeko process can then deliver a
corrective polish to produce a smooth surface of very closely controlled
figure. Wafer thickness and flatness can each be controlled depending on
the metrology feedback provided to the machine. It is believed that this
process may be able to polish semiconductor industry materials to a high and
controlled surface finish, and may have applications in strained silicon
production, dual damascene applications, in some MEMs applications, and in
some display technologies, among others. (PDF) |
| May 12 |
Host: David
Graves, University of California-Berkeley
Presentation by: Yoshie Kimura, Department of Chemical
Engineering, UC-Berkeley
Topic: "Vacuum Beam Studies of Radical-Surface and Ion-Surface
Interactions"
Abstract:
The
effects of radicals and ions from plasmas in altering surface properties
during etch, deposition, cleaning, ashing and other plasma-assisted
processes are not well understood. Current and future demands on plasma
process technology can be thought of as controlling the effects of the
plasma-surface interactions at the atomistic scale over wafer dimensions
while minimizing resource consumption and environmental, health and safety
problems. Plasma process challenges include excess loss of photoresist
during etch; photoresist roughening; control of critical dimension during
gate electrode etch; and reducing contamination and damage during porous low
k etch and ash. In this talk, I will describe an experimental system
designed to reveal fundamental information about how radicals and ions alter
surfaces. Examples will be provided of the use of this system in studying
porous low k etch processes, and various radical-surface interactions.
(PDF) |
| May 19 |
Host: David Mathine, University of Arizona
Presentation by: David
Mathine, University of Arizona
Topic: "Cell-Based
Biosensors for Toxicity Testing of New Chemicals"
Abstract: The rapid development of new chemicals makes
the current approach to toxicity testing unrealistic since the testing
relies on laborious and expensive animal testing. However, physiological
responses from cells can be used when monitoring a variety of situations
including toxicity, environmental pollutants, and responses to drugs.
Therefore, cell-based biosensors provide a useful means for collecting
information on the toxicity of new chemicals.
We will report on the development of a CMOS biochip. This chip is
designed to monitor chemical, electrical and optical responses from
mammalian cells. The design of the chip along with environmental
control will be discussed. (PDF) |
| May 26 |
Host: Ralph
Richardson, Air Products and Chemicals Inc.
Presentation by: Dr. Reinaldo M. Machado, Engineering
Research Associate, Air Products and Chemicals Inc.
Topic: "Novel Subatmospheric Gas Sources for Ion Implanters"
Abstract: Subatmospheric gas
supply technologies which serve the ion implant market are widely recognized
as the preferred supply of hazardous feed gases (e.g., BF3, AsH3 and PH3).
The most common subatmospheric supply relies on cylinders filled with
adsorbent to store dopant gases. Recently, at Air Products and Chemicals,
Inc. we have developed two novel subatmospheric supply technologies which
are both in beta-testing in commercial ion implant tools. The first
technology, Low Pressure Delivery (LPD), developed for PH3 and BF3, utilizes
a novel, non-volatile liquid that forms a reversible chemical complex with
the dopant gases allowing them to be stored at high capacity while at
subatmospheric pressure. A proprietary valve allows the canister to be used
in vertical or horizontal ion implant gas boxes and utilizes the same
manifold and mass flow system as other subatmospheric sources. The LPD
system is a drop-in replacement for adsorbent based subatmospheric gas
sources. The second technology, eGas™ arsine, is an electrochemical arsine
generator that when shipped or stored before use contains no arsine. This
unique characteristic reduces many barriers to shipping and storage. The
eGas™ arsine generator utilizes electrochemical reduction at an arsenic
cathode in a caustic electrolyte to generate a dopant gas containing 93-95%
pure arsine (5-7% hydrogen) to the ion implanter at a constant
subatmospheric pressure, currently set at 600 torr. Both technologies
generate ion beams and commercial wafers that are comparable to those
generated with other subatmospheric sources. This talk will focus on the
performance and safety properties of these systems in real ion implant
tools. (PDF) |
| June 2 |
Host: Krishna
Saraswat, Stanford University
Presentation by: Ammar Nayfeh, Department of Electrical
Engineering, Stanford University
Topic: "A Method to Grow Heteroepitaxial-Ge on Si: Multiple
Hydrogen Annealing for Heteroepitaxy (MHAH)"
Abstract: It is pivotal to develop new methods for
heteroepitaxial Germanium (Ge) technology as Ge has been emerging as a
viable candidate to augment Si for CMOS and optoelectronic applications. Ge
growth on Si is hampered by the large lattice mismatch (4%), which results
in growth that is dominated by “islanding” and misfit/threading
dislocations, rendering the layer not useful in device application. Misfit
dislocations form at the substrate/film interface and typically terminate at
the film surface as threading dislocations, thus degrading device
performance.
We report a novel technique to achieve high quality heteroepitaxial Ge
layers on Si. The technique involves CVD growth of Ge on Si, followed by
in-situ hydrogen annealing with subsequent growth and anneal steps and hence
the name Multiple Hydrogen Annealing for Heteroepitaxy (MHAH).
Our results indicate that threading dislocation segments are deposited near
the Ge/Si interface or bent parallel after hydrogen annealing indicating low
threading dislocation densities with a strong
reduction in surface roughness. The smoother Ge surface allowed for the
fabrication p and n type metal-oxide-semiconductor (MOS) capacitors
using thermally grown germanium oxynitride (GeOxNy).
In addition, we have successfully demonstrated high mobility p-MOSFETs in
MHAH grown germanium layers. This MHAH technology may lead to
subsequent bonding of Ge to Si/SiO2 needed for the fabrication of
Germanium-on-Insulator (GOI) substrates using epitaxial Ge. (PDF) |
| June 9 |
Host: Chris Ober,
Cornell University
Presentation by: Dr. Ramakrishnan Ayothi, Postdoctoral Associate,
Department of Materials Science and Engineering, Cornell University
Topic: "Non-PFOS Photoacid Generators: A potential candidate for
Next Generation Lithography"
Abstract: The resist material for 193 nm and next generation
lithography (NGL) needs to be more photosensitive (for example EUV needs 2
mJ/cm2) because the radiation flux available for imaging decreases as the
wavelength of exposure light shortens. The increased sensitivity has been
achieved by chemical amplification (CA), involving photoproduction of an
acid catalyst from a photoactive compound known as a photoacid generator (PAG).
PAGs based on long-chain perfluorinated (PFOS/PFAS) onium salts have proven
to be industrially useful over the myriad ionic and nonionic PAGs
developed. However, persistence, bioaccumulation and toxicity (PBT)
concern, high fluorine absorption at EUV, limited compatibility and
diffusion at smaller dimensions demand non-PFOS based PAGs. This
presentation will focus on the PFOS issue including some background and how
a novel class of non-PFOS based PAGs can be designed for NGL. (PDF) |
| June 16 |
Host: Rafael Reif, Massachusetts Institute
of Technology
Presentation by: Ajay Somani, Department of Materials Science, Microsystem
Technology Laboratory, MIT
Topic: "Methodology for
environmental impact evaluation with 2D v. 3D case study"
Abstract:
There is an immense need of incorporating environment as a factor in
decision making for future technologies. This can be only possible when
there is a “fast” and “simple” approach to assess the environmental
impacts/hazards of new technologies such as 3D IC. Most of new technologies
such as 3D IC and strained Si when introduced to manufacturing, they modify
or initiate set of new processes. This talk briefly outlines the method to
compare new technologies with standard processes in terms of environmental
impact. (PDF) |
| June 23 |
No TeleSeminar -- 12th Annual
ISESH Conference, Portland OR |
| June 30 |
Host: Srini
Raghavan, University of Arizona
Presentation by: Srini Raghavan, Department of Materials Science and
Engineering, University of Arizona
Topic: "Applications of Raman
Spectroscopy in Copper CMP"
Abstract: In CMP, in-situ
detection of barrier to dielectric layer transition is typically done using
reflectivity measurements. Introduction of carbon containing low-k materials
as dielectric layers has opened up the possibility of using spectroscopic
techniques for the detection of such transitions. These low-k materials,
commonly referred to as carbon doped oxides (CDO), contain C-H, Si-O and Si-C
bonds whose vibrational frequencies may be probed by spectroscopic
techniques such as Raman and IR (infrared). Since CMP is carried out in
aqueous media, water yields a strong signal and in such situations Raman
technique is much more sensitive than the IR technique. In this presentation
a novel set up that can be used to monitor Ta to CDO transition using Raman
spectroscopy will be described. This set-up integrates an abrasion (small
scale CMP) cell with a Raman spectrometer. The sensitivity of the Raman
technique will be compared to that of the commonly used reflectivity
technique. Other applications of this technique in copper CMP will be
discussed. [S. Kondoju, P. Lucas, and S. Raghavan, Department of Materials
Science and Engineering, University of Arizona; work supported by Intel
Corporation] (PDF) |
| |
SUMMER BREAK > July 7, 2005 through September 1,
2005
[NOTE: As of September 8th, TeleSeminars will be offered every other
Thursday] |
| Sept. 8 |
Host: Farhang Shadman,
Department of Chemical and Environmental Engineering, University of Arizona
Presentation by: Asad Iqbal, University of Arizona
Topic: "Removal of Moisture Contamination from Porous
Polymeric Low-k Dielectric Films"
Abstract: New interlayer low-k materials are needed to
address power consumption problems, signal propagation delays, and
cross-talk between interconnects in the next generation of integrated
circuits. Porous low-k dielectrics (such as MSQ, methylsilsesquioxane) are
among candidates to replace SiO2 as the inter layer dielectric material.
Integration of low-k dielectrics in manufacturing environment requires a
better understanding of the challenges and issues that are associated with
the characteristics of these new materials. Atmospheric Molecular
Contamination can affect the properties of the interlayer dielectric films,
which can in turn affect the process yield and degrade the final device
performance. Understanding the transport of gases through these low-k
dielectric materials will assist in designing better processes for
integration of low-k material in semiconductor processing. The interaction
of moisture with porous spin-on dielectric material is investigated using
Atmospheric Pressure Ionization Mass Spectrometry (APIMS). The model
compound is MSQ based dielectric with k ~ 2.2 and pore diameter ~ 1.7nm. A
process model is developed that provides information on the dynamics of
moisture adsorption and interaction with thin MSQ films and surface. Using
this model, the role of physical and geometric properties of the low-k film
has been determined and method for optimum design and selection of low-k
material is presented. (PDF) |
| Sept. 22 |
Host: Paul
McIntyre, Stanford University
Presentation by: Hemant Adhikari, Department of Materials
Science and Engineering, Stanford University
Topic: "Ge Nanowire Epitaxy by
CVD: Shape Control, Orientation Selection and Surface Passivation"
Abstract:
We will
present the results of growth of vertically aligned defect-freesingle-crystalline
germanium nanowires at temperatures of 350°C or less by metal nanoparticle-catalyzed
chemical vapor deposition. Single crystal Ge (111), Ge (110), Ge (001) and
an epitaxially-grown Ge film on a Si (001) wafer were used to explore the
epitaxial relation between the nanowires and the substrate. Various
passivation routes for nanowires such as hydrogen termination and chlorine
termination were studied by photoelectron spectroscopy using a low energy
synchrotron source. (Authors: Hemant
Adhikari, Shiyu Sun, Ann Marshall, Pierro Pianetta,Christopher
E.D. Chidsey, Paul C. McIntyre - Stanford University) (PDF) |
| Oct. 6 |
Host: Anthony
Muscat, University of Arizona
Presentation by: Michael Durando, University of Arizona
Topic: "Methods and Kinetics of
Copper Etching Using hfacH in Supercritical CO2"
Abstract: Over the past decade
the semiconductor industry has aggressively investigated supercritical
carbon dioxide (scCO2) to reduce the consumption of aqueous and
organic solvents and to achieve technological goals unattainable with
conventional solvents. Pilot studies with full wafers, however, showed mixed
success, causing many companies to put scCO2 technology on the
backburner. Processing in the chemical, pharmaceutical, and related
industries is done using scCO2, and the fundamental processing
science is an active research area. In particular, the kinetics and
mechanisms of heterogeneous reactions taking place on solid surfaces
immersed in a supercritical fluid are not well understood. In this work,
copper metal films were etched using scCO2 to characterize this
process for use in backend processing. (PDF) |
| Oct. 20 |
Host: Karen Gleason,
Department of Chemical Engineering, MIT
Presentation by: Dr. Kelvin Chan, Process Engineer, Applied Materials
Inc.
Topic: "Air Dielectric:
CVD Sacrificial Materials"
Abstract:
Thin film of a polymeric sacrificial material based on poly(cyclohexyl
methacrylate) (PCHMA) was synthesized using initiated chemical vapor
deposition (iCVD). iCVD is able to make cross-linked PCHMA in situ on the
surface of a substrate in one step without using any solvents. Although
cross-linked, the material was found to decompose cleanly, leaving behind a
maximum of 0.3% of residue by thickness upon completion of annealing.
Cross-linking renders the polymer stable in practically all solvents, so the
photoresist used for patterning can be removed by dissolution instead of
ashing. The high etch rate (0.35 microns/min) in oxygen reactive-ion etching
in addition to the stability in solvents eliminates the need of a hard mask
during etching. This use of no hard mask represents an improvement over
previously-reported spin-on sacrificial materials. Infrared spectroscopy and
solubility tests confirm the identity of the iCVD polymer and its stability
in solvents. The onset of thermal decomposition is 270 °C, meaning that the
polymer can survive other high-temperature processing steps. Fabrication
using conventional lithographic, etching, and deposition techniques resulted
in void structures having feature sizes of a minimum of 1.5 microns, as
visualized using environmental scanning electron microcopy. With better
lithographic technologies, void structures of smaller feature sizes can be
fabricated. This work represents a novel approach, combining the rationale
behind cross-linking and the technique required for synthesize, of air-gap
fabrication using a sacrificial polymer. (PDF) |
| Nov. 3 |
Host: Christopher
Ober, Cornell University
Presentation by: Nelson Felix, Cornell University
Topic: "Molecular
Photoresist Systems Developable in Supercritical CO2"
Abstract: Today's
conventional microelectronic fabrication processes are able to produce
features in the 100nm range or lower. However, tighter regulations on toxic
chemical release, as well as the increasing energy cost associated with
treating rinse water, means that the semiconductor industry is primed for
the adoption of alternative solvent processes. Supercritical CO2 (scCO2) is
a promising candidate as a replacement solvent. It is inexpensive,
environmentally benign, combines the best properties of both a gas and
liquid, and can be easily separated from solutes. We have recent shown
scCO2 to be a prime replacement solvent for photoresist development, and
have formulated photoresists for both positive and negative tone development
processes. We demonstrate the solubility of smaller non-polymeric compounds
in supercritical CO2. These small molecules, also known as molecular
glasses, form amorphous films on planar substrates and show excellent
solubility in scCO2 without the incorporation of fluorine or silicon. Using
a phenolic-based molecular glass, photoresist features smaller than 100nm
were developed in scCO2. (PDF) |
| Nov. 17 |
Host: Ara
Philipossian & Yun Zhuang, University of Arizona
Presentation by: Professor Chris Rogers, Department of
Mechanical Engineering, Tufts University
Topic: "Pad Deformation"
Abstract: At Tufts University,
we have been working the last eight years to measure slurry behavior during
polish in an effort to better understand how to model it. We have been able
to measure the slurry layer age, temperature, and thickness during full
polishing conditions using DELIF or dual emission laser induced
fluorescence. We have also been able to look at how the pad conforms to
changes in surface topography by using a YAG laser to "freeze" the flow. I
will give a brief overview of the results we have seen so far and end with
some of the pictures the pad compression during polish. (PDF) |
| Nov. 24 |
No TeleSeminar -- THANKSGIVING
HOLIDAY |
| Dec. 1 |
Host: Duane Boning,
Department of Materials Science,
Microsystem Technology Laboratory, Massachusetts Institute of Technology
Presentation by: Ajay Somani,
Department of Materials Science,
Microsystem Technology Laboratory, MIT
Topic: Methodology
for environmental impact evaluation - 2D vs 3D case study
Abstract: There is an
immense need of incorporating environment as a factor in decision making for
future technologies. This can be only possible when there is a fast and
simple approach to assess the environmental impacts/hazards of new process
technologies such as three-dimensional integrated circuits (3D IC) and
strained silicon. These new technologies when introduced to manufacturing,
they modify or initiate set of new processes. This talk briefly outlines the
method to compare new technologies with standard CMOS processes in terms of
environmental impact. This methodology facilitates in identifying
environmentally hazardous unit processes earlier in research phase. This
provides a chance to improve this unit process optimized for cost,
performance and EHS before it goes to manufacturing. This seminar
illustrates the particular approach using MIT 3D IC as a case-study. (PDF) |
| Dec. 15 |
Host: Reyes Sierra,
University of Arizona
Presentation by: Dr. Frank Weber, Interconnect Division,
SEMATECH (assignee from Infineon Technologies AG)
Topic: "Advanced
Cleans --- a Structured Approach"
Abstract: Up to now the development
of a cleaning process was mostly by trial and error by experienced
engineers, but with the introduction of carbon containing porous materials
and their sensitivity to upstream (mainly etch and ash) processes
this approach had to be changed.
The cleaning process was cut into smaller defined sub-steps and
investigated. For the wetting step different treatments of ultra-low
k materials have been measured and for the dissolving step the
concept of a material stability area has been developed to streamline future
evaluation processes. This approach will
allow prediction of a solvent's performance and selection of the most
environmentally benign chemical. (PDF) |
| Dec. 29 |
No TeleSeminar - CHRISTMAS
BREAK AT U. OF A. |
|
