Contamination Control in Vacuum
N E W S
by Jennifer Ouellette
s silicon device densities increase and
dimensions become ever smaller, the
semiconductor industry is striving to control
contamination in vacuum manufacturing
environments to increase product yields and
profit margins. Vacuum technology compa-
nies are exploring the use of magnetically
levitated devices, which use unlubricated
bearings to reduce friction between vacuum
components, in situ monitoring systems, and
experiments and computer simulations to
better understand the behavior of particles in
a vacuum processing system.
While vacuum technology is used primari-
ly to provide the proper environment for cer-
tain manufacturing processes, its usefulness
in contamination control cannot be over-
looked. Controlling secondary contamina-
tion is particularly important for many man-
ufacturing industries that use metal deposi-
tion and thin-film technology, such as tool
coatings, architectural glass, camera and
laser lens coatings, and aluminized plastic
food packaging. It is also a key factor in sur-
face science and high-energy accelerator
physics applications, where even minute
degrees of contamination disrupt measure-
ments. In fact, the success of the $1.2 billion
National Ignition Facility under construction
at the Lawrence Livermore National Labora-
tory (LLNL) in Livermore, California, is high-
ly dependent on both vacuum and atmos-
pheric related contamination control ,
according to Howard Patton, a specialist in
vacuum contamination control at LLNL.
In the semiconductor industry, contami-
nation control is one of the key aspects of
yield management, since improving a fabri-
cation facility’s yield by just a few percent
can result in millions of dollars in increased
profits. Allan Bowling, director of process
development for Texas Instruments’ R&D
fabrication facility, reports that an estimated
80% of equipment failures in silicon wafer
process lines arise from contamination-relat-
ed defects. Since most wafer fabrication lines
average an 80% yi