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Performance
of 50 Completed ATP Projects
Status
Report - Number 2
NIST SP 950-2
Chapter
4 - Electronics, Computer Hardware & Communications
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FSI
International, Inc.
A Gas Method to “Dry” Clean
Computer-Chip Wafers
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| Manufacturing
processes create parts for further assembly or final use, as well
as a certain amount of waste. Even if waste is severely controlled,
the part that emerges from fabrication is almost always contaminated
to a greater or lesser degree by unwanted particles. The level of
unwanted particles varies with the process, and so does its effect
on the rest of production. If the new part is a slice of silicon crystal
about to be covered by microscopic integrated circuits, the presence
of unwanted particles — even in minute amounts — is disastrous.
Extreme cleanliness, therefore, is the rule in silicon chip-making
plants, where fabrication takes place in clean rooms designed to eliminate
contamination. |
COMPOSITE
PERFORMANCE SCORE
(Based on a four star rating.)
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New Technology to
Clean Ever Smaller Chip Features
In computer-chip fabrication, a silicon-crystal wafer is thoroughly cleaned
before microscopic electronic components are deposited on it. Conventional
cleaning techniques use caustic wet chemicals that could be hazardous
to workers and that must be discarded after use, generating disposal costs
and the potential for environmental pollution if the chemicals are not
handled properly. In addition, for chips with feature sizes below a minimum,
wet chemicals may not be able to get to some features, such as trenches,
because of surface tension.
Potentially Safer
and Less Costly
The ATP award allowed FSI International, which provides semiconductor
wafer surface conditioning equipment and support products, to develop
a “dry” cleaning procedure that uses chlorine, chlorine/hydrogen,
and other gases to clean dirt, trace metals, and other particles from
wafer surfaces. Researchers completed the assembly and installation of
an experimental module and developed required support processes. Although
the gases are toxic, they are more easily controlled than wet chemicals.
And even though the gases incur disposal costs, the amount of chemical
waste generated by the FSI technology is expected to be much smaller than
that created via traditional wet cleaning. Thus, the new technology should
improve human and environmental safety and reduce cleaning costs during
wafer processing.
FSI’s methodologies
for gas-phase dry cleaning were developed for use in making computer chips
and have potential applications in the fabrication of printed circuit
boards, disk drives, and optoelectronics. If the market emerges and the
FSI technology becomes widely used, substantial economic benefits would
likely accrue all along the supply chain for computers and other equipment
that include chips. The technology is undergoing initial testing at Texas
Instruments. If the testing is successful, FSI officials say, Texas Instruments
would likely buy and use systems incorporating the new technology.
ATP funding was critical
to generating the gas-phase dry cleaning technology, FSI officials report.
The company would not have done the research and development work at that
time without it. The ATP award also enabled FSI to collaborate with Massachusetts
Institute of Technology researchers during the project.
Commercialization
Delayed but Still Expected
Since initiation of the ATP project, manufacturers of wafer-surface conditioning
equipment have found ways to squeeze more improvements out of wet-chemical
cleaning methods. Consequently, chip fabricators have less need for a
dry cleaning technique than was initially anticipated. The company expected
that the shift in 1997 to smaller (0.25 micron) minimum feature sizes
for wafer processing would challenge the capabilities of conventional
wet cleaning processes. Wet processing, however, continues to meet cleaning
needs at this level and may even be viable to minimum feature sizes of
0.18 micron, which are expected to be introduced in 2000. Furthermore,
progress has been made in reducing the amount of chemicals needed for
wet cleaning processes.
Commercialization
of the ATP-funded technology, therefore, depends on how much more the
wet method can be extended, as well as on the remaining development work
needed to demonstrate the robustness, manufacturability,
and reliability of the process and equipment in a chip-manufacturing environment.
Although the new technology has not become a broad replacement for traditional
wet cleaning in wafer processing, as originally envisioned by the ATP-project
proposal, FSI anticipates the emergence of new applications requiring
the unique capabilities of its technology. If the dry cleaning technology
is commercialized, chip fabricators that use the new technology might
achieve process improvements worth up to five times their costs for the
technology, company officials say. FSI has continued to develop this technology
while delaying commercialization until demand increases sufficiently.
If that happens soon, the company could have a product on the market in
1999.
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Project
Highlights
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PROJECT:
To develop a cost-effective process to remove surface contaminants
from computer-chip wafers during manufacturing, using dry gases
(as opposed to wet chemicals) that can clean the ever smaller features
on new generations of chips.
Duration: 3/1/1993 — 2/28/1995
ATP Number: 92-01-0022
FUNDING (in
thousands):
| ATP |
$2,000
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36%
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| Company |
3,482
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64%
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| Total |
$5,482
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ACCOMPLISHMENTS:
FSI achieved its R&D goal of developing a dry gas wafer-cleaning
method. Evidence of progress is that the company:
- received
three patents related to the ATP project:
“UV-Enhanced Dry Stripping of Silicon Nitride Films”
(No. 5,534,107: filed 8/18/1994, granted 7/9/1996),
“Apparatus for Surface Conditioning”
(No. 5,580,421: filed 12/21/1994, granted 12/3/1996), and
“Cleaning Method”
(No. 5,716,495: filed 3/25/1996, granted 2/10/1998);
- applied for
nine additional patents, one of which has been unofficially granted
(allowed but not yet published);
- presented
or published nine technical papers in the area of dry cleaning,
etching or stripping of surfaces;
- received
a license to complementary technology that could accelerate the
commercialization of an advanced dry gas-phase cleaning system;
- entered into
an agreement with Texas Instruments for early-stage testing of
a prototype; and
- constructed
a manufacturing facility to handle all FSI International Surface
Conditioning Division manufacturing, including products incorporating
the ATP-funded technology.
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CITATIONS
BY OTHERS OF PROJECT’S PATENTS: See Figure 4.8.
COMMERCIALIZATION
STATUS:
No commercialization has occurred so far, owing to unanticipated
changes in demand for the new technology. The shift in 1997 to 0.25-micron
minimum feature sizes for wafer processing was expected to challenge
the capabilities of conventional wet cleaning processes. Wet processing,
however, continues to meet cleaning needs for 0.25-micron features
and may even be viable to minimum sizes of 0.18 micron, which are
expected to be introduced in the year 2000.
OUTLOOK:
Commercialization prospects are uncertain. Much depends on how the
market moves, as well as on remaining development work needed to
demonstrate the robustness, manufacturability and reliability of
the process and equipment in a chip-manufacturing environment. Although
the ATP-funded technology has not replaced traditional wet cleaning
in chip processing, as originally envisioned by the ATP-project
proposal, FSI anticipates the emergence of new applications requiring
the unique capabilities of its technology.
Composite
Performance Score:
COMPANY:
FSI International, Inc.
322 Lake Hazeltine Drive
Chaska, MN 55318-1096
Contact:
Jeff Butterbaugh
Phone: (612) 448-8089
Number of Employees: 540 at project start, 1,295 at the end
of 1997
Unofficial collaborator: Massachusetts Institute of Technology,
Department of Chemical Engineering
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of Contents or go to next section.
Date created: April
2002
Last updated:
April 12, 2005
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