Page 12 - Science at the nanoscale

15:10
RPS: PSP0007 - Science-at-Nanoscale
June 9, 2009
Introduction and Historical Perspective
2
are famed for their beautiful stained glass windows. The same
process is used for various glazes found on ancient, antique
glazes. The colour in these antiques depends on their nanoscale
characteristics that are quite unlike microscale characteristics.
The modern origins of nanotechnology are commonly attri-
1
buted to Professor Richard Feynman, who on December 29th
1959 at the annual meeting of the American Physical Society at
Caltech, delivered his now classic talk “There’s Plenty of Room
2
at the Bottom”.
He described the possibility of putting a tiny
“mechanical surgeon” inside the blood vessel that could locate
and do corrective localized surgery. He also highlighted a number
of interesting problems that arise due to miniaturisation since “all
things do not simply scale down in proportion”. Nanoscale mate-
rials stick together by molecular van der Waals attractions. Atoms
also do not behave like classical objects, for they satisfy the laws
of quantum mechanics. He said, “... as we go down and fiddle
around with the atoms down there, we are working with different
laws, and we can expect to do different things.” Feynman said he
was inspired by biological phenomena in which “chemical forces
are used in repetitious fashion to produce all kinds of weird effects
(one of which is the author)”. He predicted that the principles of
physics should allow the possibility of manoeuvring things atom
by atom.
Feynman described such atomic scale fabrication as a bottom-up
approach, as opposed to the top-down approach that is commonly
used in manufacturing, for example in silicon integrated circuit
(IC) fabrication whereby tiny transistors are built up and con-
nected in complex circuits starting from a bare silicon wafer. Such
top-down methods in wafer fabrication involve processes such
as thin film deposition, lithography (patterning by light using ch01
masks), etching, and so on. Using such methods, we have been
able to fabricate a remarkable variety of electronics devices and
machinery. However, even though we can fabricate feature sizes
below 100 nanometres using this approach, the ultimate sizes at
which we can make these devices are severely limited by the
1 Feynman was one of the recipients of the Nobel Prize in Physics in 1965 for his
work on quantum electrodynamics. He was also a keen and influential popu-
lariser of physics in both his books and lectures.
2 Engineering and Science, Caltech, February 1960.