Ken Kubos

http://www.physorg.com/news91729711.html

Supercomputing Simulations Support Chip Breakthrough
by Nicole Herfurth

Image of a typical model of hafnium silicates used in this study. A
zoomed-in view is shown. The model contains more than 600 atoms and 5000
electrons. It is rendered in a so-called ball-and-stick graphical
representation, where the balls represent atoms (silicon in orange, hafnium
in blue and oxygen in red) and the sticks represent the chemical bonds. On
the basis of these models, IBM researchers calculated the important
electronic properties and behavior of hafnium silicate.

IBM researchers today announced an advancement in computer-based simulations
that is helping to drive chip technologies to new heights of performance and
function. As reported in the scientific journal Physical Review Letters, a
team of scientists at IBM's Zurich Research Laboratory for the first time
used advanced supercomputer-based models to more deeply understand and
master the complex behavior of a promising new material -- hafnium
dioxide -- in silicon transistors, the fundamental building blocks of
computer chips.
The new material is key to the company's recently-announced "high-k metal
gate" technology, the first major change to the transistor since the
emergence of silicon semiconductors, promising enhanced chip performance to
benefit computers and other electronic systems. IBM is implementing the
technology and will apply it to products in 2008.

The semiconductor industry has long sought to find a new material for a
crucial part of the transistor known as the gate dielectric, which, with the
materials used currently, is limiting the industry's ability to keep pace
with the progress predicted by Moore's Law -- a maxim predicting a doubling
of the number of transistors on a chip, and an associated increase in chip
performance, every 12-18 months.

While hafnium dioxide appeared to be an ideal candidate for next-generation
transistor gates, the introduction of any new material in semiconductors can
have unforeseen consequences, so it must be thoroughly understood
beforehand. One critical factor contributing to IBM's success in the highly
complex and difficult task of integrating these new materials has been
simulation of the interaction of this material at the atomic level.

Scientists at IBM's Zurich Research Laboratory have used their long-standing
expertise in computer-based modeling, together with the capabilities offered
by the IBM Blue Gene supercomputer, to determine why hafnium dioxide works
so much better than other high-k materials previously considered by the
industry. As a result, the researchers were able to gain a clear picture --
for the first time -- of the underlying physics driving the unique
electrical behavior of hafnium dioxide when it mixes with silicon, as
observed in laboratory experiments, shedding light on the reasons that make
this material unique as gate dielectric.

For this study, the IBM team simulated various material compositions using
50 different models of hafnium silicates, materials that form when silicon
and hafnium oxides mix. These models contain up to 600 atoms and approx.
5,000 electrons, representing a realistic system. A single calculation of
the dielectric constant was accomplished in only five days of computing time
on the two-rack Blue Gene/L supercomputer (4096 processors) installed at the
Zurich lab's site. The complete simulation for all 50 models, approx. 250
days on Blue Gene, would normally take the most powerful laptop PC an
astounding 700 years to calculate. This corresponds to a staggering 200
billion billion (2 x 10^20) operations.

This work illustrates how supercomputing modeling techniques are bringing
technologies of all kinds to a new level. Computer simulations have been
possible since the 1980s, but only now -- thanks to the evolution of
algorithms and their mapping to such an extremely scalable and balanced
architecture as that of the Blue Gene computer -- scientists are able to
tackle these types of problems by creating realistic models with several
thousands of particles, starting only from the laws of nature.

"Advances in algorithms and their optimal mapping on extremely large and
scalable computer hardware such as Blue Gene are empowering us to do
accurate and realistic atomic simulations of complex materials," explains
Alessandro Curioni, supercomputing expert from IBM's Zurich lab and
emphasizes: "So indeed, today we are able to use supercomputers to
investigate materials that will be eventually used in the next generation of
supercomputers."

The approach used by the IBM team is called ab initio molecular dynamics,
where the interactions between the particles of the system are derived from
the basic laws of physics without employing any empirical data. In the
course of their ground-breaking work, the IBM team created more than 50
realistic virtual models of the hafnium silicates with various
concentrations of hafnium on the supercomputer. They then simulated the
evolution of these structures over a given time period, estimated their
dielectric constants and used these results to rationalize experimental
findings.

The advantage of computer-based simulations is that, being virtual, they are
free of the problems inherent to laboratory experiments, such as the effects
of preparation conditions, the purity of the compounds, or the presence of
parasitic reactions. Most importantly, with the simulations one can follow
what the individual atoms are doing. Computer simulations allow the
"intrinsic" and ideal characteristics of a material to be calculated and
correlated directly with the structure at an atomic level.

Source: IBM

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Ken

"Buddhism elucidates why we are sentient."
"Buddhism follows thought throughout the Universe."
"Karma means that you don't get away with anything."