INDIA IMP vFinal DR 17/6/08 09:17 Page 39
Semiconductor India
Fabrication of nano
multigate organic TFT
Maskless lithography has been used to
fabricate nano electrodes for organic thin
film transistors. 15 and 30 micron strips
have been created using maskless
lithography system, as shown below in
Figure 4. FIB is used to make Al nano
electrodes within these channels.
Fabricated channels are shown in Figure 5.
Development of micro size
patterned photoresist
surfaces
The maskless photolithography system is
being used for making patterns on different
negative photoresists, such as SU 8. The
minimum feature size that can be patterned Figure 5-Nano electrode fabricated in 15 micrometer strip initially created by maskless
by this system is approximately 5 micro lithography
metres on these surfaces.
different shapes, such as pillars, channels, coated films on silicon. By controlling the
These patterned photo resist surfaces can be and cross channels. These structures are stress and adhesion in negative photoresist
used as a master stamp or as a mould for then pyrolyised to provide a carbon rich patterned thin films by UV exposure,
generating other patterned surfaces of surface. Applications for these types of uniform buckles can be introduced.
different materials and surface structures. devices are wide spread and include
microbatteries. By patterned exposure of UV, this
Patterned carbon structures phenomenon may also be of use in various
Another application for our system is to Buckling study of UV applications like fabrication of micro
pyrolyse the patterned surfaces of polymers exposed patterns channels for micro fluidics.
to obtain patterned carbon structures. The Buckling phenomenon is also being studied
maskless lithography system is used to by uniform exposure of UV radiation on Summary
pattern SU-8 negative photoresist in selective areas of negative photoresist Maskless lithography has been shown to be
a vital technique in our lab for rapidly
prototyping many state of the art electronic
and microfluidic devices. Many examples
have been shown, where the same system
and basic techniques are applied for device
fabrication.
These are only a small sampling of the
work that has been performed on the system
and we expect that the number of
Figure 4-Organic TFT’s fabricated using maskless lithography. The left photo shows a applications and uses for maskless
15 um strip, where both 15 and 30 um strips are shown in the right photo. photolithography will grow over time.
REFERENCES:
Acknowledgements: The authors acknowledge the financial support provided by the DST Unit on Nanosciences. Also, authors wish
to thanks Prof. Y N Mahaptra and Dr. Anjan K Gupta for providing images.
Summer 2008 | www.semiconductor-india.com 39
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