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FIB Nanolithography
Contact: Dr Arous Arshak
Dept. of Physics,
University of Limerick
E-mail: Arousian.Arshak@ul.ie
Tel. +353-61-202371
Semiconductor fabrication techniques are the key to the major advances in the
current complementary metal-oxide-semiconductor (CMOS) technology and to
realizing new functional quantum devices such as single electron transistors.
Various nanofabrication techniques using photons, electrons and ions have been
investigated over the last 20 years. Focused ion beam (FIB) technology is one of
the most promising techniques for nanofabrication because of its distinct
advantage of being a maskless process and in that it provides great flexibility
and simplicity.
Since FIB technology was introduced into the semiconductor industry in the early
1980s, it has become a routine analytical tool for IC device analysis, circuit
repair and advanced specimen preparation. Nowadays, FIB tools are commonly used
in semiconductor, data storage and materials science industries. A FIB machine
is very versatile and it can remove and deposit various types of materials
including conductors and insulators with sub-micron precision. This function
allows us to achieve tasks such as direct ion milling, chemical etching, ion
implantation, and chemical deposition. Another important FIB function for the
semiconductor industry is the ability to repair/modify IC circuits, in which the
interconnects can be easily rerouted over specific chip areas by selective
material removal and deposition. For example, the FIB method is used routinely
to repair optical binary masks for 193 nm lithography.
 Fig.
1 (a) FIB image of 1 μm
lines/spaces and 0.1 μm
lines/spaces in 1.5 μm
thick SPR660 after the two-step NERIME process;
(b) FIB image of 80 nm lines in 0.3 μm
SPR660 resist, produced by the two-step NERIME process;
(c) FIB image of 65 nm lines in 0.3
μm SPR660 exposed at Ga+ FIB doses of 8.15 x 10-3, 1.2 x
10-2 and 1.6 x 10-2 C/cm2, respectively;
(d) FIB image of the University of Limerick logo, exposed at Ga+ FIB doses of
1.5 x 10-2 C/cm2 and dry developed for 400 s at 0.05 mTorr. |
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