Toward ever-more powerful microchips and supercomputers

Date:
March 8, 2022
Source:
DOE/Princeton Plasma Physics Laboratory
Summary:
A look at the process to extend 'Moore's law,' which has doubled
the number of transistors that can be packed on a microchip roughly
every two years, and develop new ways to produce more capable,
efficient, and cost- effective chips.



FULL STORY ==========================================================================
The information age created over nearly 60 years has given the world
the internet, smart phones and lightning-fast computers. Making this
possible has been the doubling of the number of transistors that can
be packed onto a computer chip roughly every two years, giving rise to
billions of atomic-scale transistors that now fit on a fingernail-sized
chip. Such "atomic scale" lengths are so tiny that individual atoms can
be seen and counted in them.


========================================================================== Physical limit With this doubling now rapidly approaching a physical
limit, the U.S.

Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL)
has joined industry efforts to extend the process and develop new ways to produce ever-more capable, efficient, and cost-effective chips. Laboratory scientists have now accurately predicted through modeling a key step in atomic-scale chip fabrication in the first PPPL study under a Cooperative Research and Development Agreement (CRADA) with Lam Research Corp.,
a world-wide supplier of chip-making equipment.

"This would be one little piece in the whole process," said David Graves, associate laboratory director for low-temperature plasma surface
interactions, a professor in the Princeton Department of Chemical
and Biological Engineering and co-author of a paper that outlines
the findings in the Journal of Vacuum Science & Technology B. Insights
gained through modeling, he said, "can lead to all sorts of good things,
and that's why this effort at the Lab has got some promise." While the shrinkage can't go on much longer, "it hasn't completely reached an end,"
he said. "Industry has been successful to date in using mainly empirical methods to develop innovative new processes but a deeper fundamental understanding will speed this process. Fundamental studies take time
and require expertise industry does not always have," he said. "This
creates a strong incentive for laboratories to take on the work."
The PPPL scientists modeled what is called "atomic layer etching"
(ALE), an increasingly critical fabrication step that aims to remove
single atomic layers from a surface at a time. This process can be used
to etch complex three- dimensional structures with critical dimensions
that are thousands of times thinner than a human hair into a film on a
silicon wafer.

Basic agreement "The simulations basically agreed with experiments as a
first step and could lead to improved understanding of the use of ALE for atomic-scale etching," said Joseph Vella, a post-doctoral fellow at PPPL
and lead author of the journal paper. Improved understanding will enable
PPPL to investigate such things as the extent of surface damage and the
degree of roughness developed during ALE, he said, "and this all starts
with building our fundamental understanding of atomic layer etching."
The model simulated the sequential use of chlorine gas and argon plasma
ions to control the silicon etch process on an atomic scale. Plasma,
or ionized gas, is a mixture consisting of free electrons, positively
charged ions and neutral molecules. The plasma used in semiconductor
device processing is near room temperature, in contrast to the ultra-hot
plasma used in fusion experiments.

"A surprise empirical finding from Lam Research was that the ALE process
became particularly effective when the ion energies were quite a bit
higher than the ones we started with," Graves said. "So that will be
our next step in the simulations -- to see if we can understand what's happening when the ion energy is much higher and why it's so good."
Going forward, "the semiconductor industry as a whole is contemplating
a major expansion in the materials and the types of devices to be used,
and this expansion will also have to be processed with atomic scale
precision," he said.

"The U.S. goal is to lead the world in using science to tackle important industrial problems," he said, "and our work is part of that." This study
was partially supported by the DOE Office of Science. Coauthors included
David Humbird of DWH Consulting in Centennial, Colorado.


========================================================================== Story Source: Materials provided by
DOE/Princeton_Plasma_Physics_Laboratory. Original written by John
Greenwald. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Joseph R. Vella, David Humbird, David B. Graves. Molecular
dynamics study
of silicon atomic layer etching by chorine gas and argon
ions. Journal of Vacuum Science & Technology B, 2022; 40 (2):
023205 DOI: 10.1116/ 6.0001681 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220308105151.htm

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