Foundries at the Forefront

TSMC pioneered in 1987 the concept
of a pure-play foundry. Before that, “If
you had a new idea, you really didn’t
have a place where you could test it”
without paying for a dedicated factory,
Gargini said. The advent of foundry ca-
pacity was “the best thing that could
have happened for the industry,” he
said. “The iPhone would never have ex-
isted if we didn’t have this model.”
At first, TSMC replicated older, less-
profitable technologies and grew by
“taking the rejects from the leading
semiconductor companies.” Gargini
said. However, “by 2000 or so they were
within shooting range of the leading
companies.”
Later foundries have mostly con-
fined themselves to following the lead-
ers, but GlobalFoundries seemed to
have higher aspirations. The company
was created in 2009 from the manu-
facturing operations of Intel’s arch-
competitor Advanced Micro Devices
(AMD). The company also acquired
Singapore-based foundry Chartered
Semiconductor, and in 2015 added the
manufacturing operations of IBM.

Leading-edge semiconductor manufacturing is expensive and challenging, which is one reason AMD and IBM divested that part of their businesses. Into the 1990s, keeping up with Moore’s Law could mostly be achieved by “ scaling,” following rules laid out by IBM’s Robert Dennard in 1974 to make better transistors by shrinking lateral dimensions, shrinking layer thicknesses, and increasing doping densities. Packing more transistors on the surface area of a wafer also offered benefits such as reduced cost per transistor, higher speed, and lower power dissipation.

Continued exponential shrinkage brought transistors into collision with fundamental physical limits, though, such as gate oxides just a few atom-lay-ers thick, as well as large leakage currents and other non-idealities in the tiny devices. To sidestep these limits, in the early 2000s manufacturers introduced multiple revolutionary innovations, such as high-dielectric-constant (high-k) gate dielectrics, metal gates, strained silicon, and the nonplanar transistors known as FinFETs.

More innovation will be needed,
including in process technology. Espe-
cially challenging has been the lithog-
raphy that prints the circuits, using
progressively shorter ultraviolet wave-
lengths to create tinier features. This
shrinkage stalled for years at a wave-
length of 193 nm because the next huge
jump, to extreme ultraviolet (EUV) at
13.5nm, requires different sources, op-
tics, and exposure techniques. Instead,
designers have exploited liquid immer-
sion, multiple exposures, and other
tricks to extend 193nm lithography.
With the 7nm generation, EUV is final-
ly being used for some processing lev-
els, but economically viable through-
put and yield won’t come easily.

Shakeout

These challenges are not new, but the withdrawal of companies from the leading edge raises a “very valid question,” Shih said. “If there’s less competition, are we going to push the frontier less?” So far, there are still multiple suppliers.

“As long as you have two, it’s sufficient; if you have three it’s great,” Gargini said. “Samsung can do a lot of the stuff that TSMC can do,” and TSMC’s lead already meant that “there’s nothing that is so special that GlobalFoundries was doing,” Gargini said. AMD, for example, already made many of its most advanced central processing units (CPUs) and graphics processing units (GPUs) at TSMC.

Still, Shih notes that the consolidation is “troubling” for U.S. semiconductor manufacturing, because “a vast amount of the world’s advanced foundry capacity is in TSMC’s hands in three fabs in Taiwan.” He added that “People who worry about the defense-industrial base are very concerned about this issue.”

Consolidation
is “troubling” for
U.S. semiconductor
manufacturing,
because “a vast
amount of the world’s
advanced foundry
capacity is
in TSMC’s hands.”

ACM
Member
News

SEEKING NEW WAYS TO BUILD AND MAINTAIN OPEN DISTRIBUTED SYSTEMS

Gul Agha is a
professor in the
Department of
Computer
Science, and
director of the
Open Systems
Laboratory, at the University of
Illinois at Urbana-Champaign.
Agha received his undergrad-
uate degree from the California
Institute of Technology. He
earned a master’s degree in psy-
chology and a Ph.D. in computer
and communication science
from the University of Michigan
at Ann Arbor, but did his disserta-
tion research at the Massachu-
setts Institute of Technology.
In 1989, he joined the faculty
at the University of Illinois,
where he has remained ever
since. “One of the joys of being
an academic,” Agha says, “has
been my ability for life-long
learning and to acquire new
knowledge and perspectives.”
“My research has
spanned diverse areas such
as programming languages,
software engineering, cyber-
physical systems, and formal
methods,” Agha says. “I want to
develop unifying programming
abstractions for new generation
of applications, such as Io T (the
Internet of Things) for Smart
Cities.” These applications
require concurrency and
coordination, notions of
approximation and stochastic
behavior, and integration with
continuous spatiotemporal
variables.

A real-world project on which Agha collaborated was the implementation of the world’s largest sensor network to continuously monitor the structural health of South Korea’s 484-meter Jindo Bridge, connecting the Korean mainland to Jindo Island. The sensor network promises a robust, significantly lower-cost alternative to traditional structural inspection techniques, Agha says.