ECE helps Imago carry out its BIG VISION for seeing
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p close,
Imago Scientific Instrument’s atom probe is a veritable jungle
of glinting steel, glowing ports and snaking hoses and wires. This microscope
that lets scientists peer at the very atoms that compose matter does
so by an intricate process, first plunging specimens to temperatures
near absolute zero and then pulling atoms from them one by one. The
atoms next fly to a detector, where they are identified and their positions
in three dimensions pinpointed—all at the rocketing pace of 50
million atoms per hour.
Known officially as the local electrode atom probe
(LEAP) microscope, this remarkable machine is the brainchild of Tom
Kelly, a former UW-Madison professor of materials science
and engineering, and Imago’s founder, chairman and chief technical
officer. Kelly may have devised the instrument while at the university,
but he is quick to pass on credit to his company’s technical team.
The 10 atom probes the group has built, shipped and installed at customer
locations since 2003 have proven highly reliable, he says; last month,
for example, every instrument was operating 100 percent of the time,
save one—it was at 96.
On top of this, he adds, each has been delivered on
time to customers and fully installed within two weeks as promised.
“For these complicated instruments, this is exceptional,”
he says. “It’s one thing to have good ideas. It’s
another thing to execute. And execution like this is the domain of engineering.”
To find the engineering prowess it relies on to succeed,
Madison-based Imago has rarely needed to look any further than its own
backyard. Like Kelly himself, most of the company’s technical
staff hails from either UW-Madison or the Madison Area Technical College.
The trend started in 1998 with the company’s very first employee,
former UW-Madison researcher Tye Gribb. Since then, Imago has tapped
over 30 graduates of UW-Madison’s science and engineering and
MATC’s electron microscopy degree programs.
The company also maintains close ties to engineering
faculty, especially those in materials science and engineering and ECE.
“Because we have to be very focused on analyzing our customers’
samples, we don’t get much time to do basic scientific research,”
says Keith Thompson, Imago’s senior applications engineer. “The
university really helps to fill that gap. Over a two- to three-year
period, we end up getting a lot of important information that we might
not otherwise get.”
Scientific partnerships with UW-Madison can also contribute
again to Imago’s own technical staff. “These collaborations
can lead to the development and education of students who then become
the next generation of Imago expert engineers and scientists to take
the technology to even greater places,” says Professor John
Booske. “It’s a very positive and powerful symbiotic
relationship.”
Booske knows of what he speaks. Thompson, who now
helps develop new applications for Imago’s atom probe, first began
working with the company while employed as a postdoctoral researcher
in Booske’s lab. The two were perfecting a step in the manufacture
of tiny semiconductor devices spanning fewer than a thousand atoms,
when they suddenly realized what they faced. “We saw that the
research questions we were pursuing amounted to asking, ‘Just
where are all the individual atoms and what type of atoms are they?’”
says Booske.
At the time, Imago’s microscope—originally
designed to probe metals—hadn’t been rigorously applied
to semiconductors. Nonetheless, Booske and Thompson soon recognized
it as their best chance to see the three-dimensional positions of atoms
within the tiny bits of material they were studying. The pair approached
Kelly, who quickly agreed to give Thompson access to Imago’s equipment
when it wasn’t in use. “Basically, nights and weekends,”
says Thompson, laughing. David Larson, a former graduate student of
Kelly’s who now serves as Imago’s director of applications,
also joined the effort.
Because atom probing requires needle-sharp specimens,
Thompson’s first task was to whittle these into the smooth surface
of a semiconductor. Metal samples for LEAP analysis resemble rough-hewn
pins—small but easily seen with the naked eye. But the semiconductor
samples needed to be much tinier: just 1/200,000th of a centimeter wide
and about 1/100th of a centimeter tall.
For help Thompson turned to UW-Madison’s Wisconsin
Center for Applied Microelectronics (WCAM), a state-of-the-art cleanroom
facility that provides equipment and expertise for making microscopic
structures of just this type.
“The WCAM facilities are top of the line, and
the staff is very knowledgeable and helpful,” Thompson says. “They
really helped get me going; without the cleanroom, I don’t know
if this project would have gone very far.”
But creating samples proved to be just half the battle.
The other major hurdle confronting the team was finding a way to pull
atoms from the samples’ sharpened ends. Because metals readily
conduct electricity, atom probing normally sends an electrical pulse
through a metallic specimen to rip atoms from its tip. But semiconductors,
as their name implies, conduct electricity only sluggishly. And when
Thompson initially tried applying voltage to his samples, they tended
to explode.
To solve this problem, Imago figured out how to wrest
atoms from semiconductors with a laser beam instead. It announced the
advance this summer.
Hired by Imago in April 2004, Thompson now routinely
analyzes samples for the company’s customers in the semiconductor
industry. “In the past, the complications of getting LEAP to work
with semiconductors were so great, people didn’t even want to
hear about it,” he says.
“Now, when I get a sample set in, we can generate
data right away—it’s a two- to three-day turnaround. And
I tell people it’s all because the foundation was laid on good
scientific principles back when I was a postdoc.”
