1. Tools to Make Nanostructures “the challenge to Moore’s Law“
Scanning Probe Instruments
Lithography
Nanoscale
Dip Pen
E-Beam
Nanosphere Liftoff
Molecular Synthesis
Self Assembly
Nanoscale Crystal Growth
Polymerization
Nanobricks
NanoCAD

2. The Return of Scanning Probe Instruments
Assembling materials atom-by- atom or molecule-by-molecule
Analogy – “bulldozer” or “crane” or “backhoe”
Elegant but slow and expensive
A series of STM images showing the numbers 0 through 10
represented by single carbon-60 molecules (buckyballs) on a
copper surface. The top row shows zero, with no molecules at
the end of the row, and the successive rows provide representations
of the numbers 1-10, with the appropriate numbers of molecules at
the end of each row.
(Image courtesy IBM Zurich Research Laboratory.)

3. Nanoscale Lithography
“silk screen or rubber stamp concept”
Micro-imprint lithography developed by George Whitesides (Harvard)
Pattern inscribed onto a rubber surface (silicon/oxygen polymer) and the rubber surface is coated with molecular ink
Complex but inexpensive and can make numerous copies
Figure 15. Two examples of imprinting over a
planarized surface.
_articles/MOT_SPIE2003_Imprint_Lith_review_paper.pdf

4. Dip Pen Lithography “fountain pen analogy”
                                                                                                                                                                                                                                                                                                                                           
“fountain pen analogy”
Developed by Chad Mirkin at Northwestern Univ.
AFM tips are ideal nanopens
Almost anything can be used as nanoink
almost any surface can be written on
Almost anystructure can be made no matter how detailed or complex
Dip-Pen Nanolithography: Transport of molecules to the surface via water meniscus.
Ultra-high resolution pattern of mercaptohexadecanoic acid on atomically-flat gold
surface. B) DPN generated multi-component nanostructure with two aligned
alkanethiol patterns. C) Richard Feynmann's historic speech written using the DPN
nanoplotter

5. E-Beam Lithography
Use of electron beam to make structures at nanoscale
Applications in microelectronics
Figure 4.4. Two electrodes made using E-beam lithography. Thelight horizontal structure is a carbon nanotube.
Courtesy of the Dekker Group, Delft Institute of Technology.

6. Nanosphere Liftoff Lithography
Figure 4.5. Schematic of the nanosphere liftoff lithography process.
Courtesy of the Van Duyne Group, Northwestern University.

7. Molecular Synthesis - making specific molecules for specific purposes - drug delivery techniques - extensive molecular synthetic work in drug companies (e.g. Lipitor, Penicillin, Taxol, Viagra)

8. Self Assembly
Making nanostructures by letting the molecules sort themselves out
Molecules will always seek the lowest energy available to them
Molecules will align themselves into particular positions
Use for large nanoscale arrays, different length scales, low cost, generality
Electronic applications, coatings
Figure 4.6. Molecular model (top) of a self-assembled
"mushroom" (more correctly a rodcoil polymer). The
photograph (bottom) shows control of surface wetting by a
layer of these mushrooms.
Courtesy of the Stupp Group, Northwestern University.

9. Nanoscale Crystal Growth
“seed crystal concept”
Silicon Boules
Manipulating seed crystals to grow to unusual shapes
Charles Lieber (Harvard)
Figure 4.7. Two parallel nanowires. The light color is silicon,
and the darker color is silicon/germanium.
Courtesy of Yang Group, University of California at Berkeley.

10. Polymerization
Controlled polymerization, in which one monomer at a time is added to the next, is very important for specific elegant structures.
Robert Letsinger and his students at Northwestern University have developed a series of methods for preparing specific short DNA fragments. These are called oligonucleotides.
The so-called gene machines use elegant reaction chemistry to construct specific DNA sequences.
Figure 4.8. Schematic of the DNA hybridization process. The
"matched" side shows how a DNA strand correctly binds to its
complement and the "mismatched" side shows how errors can
prevent binding.
Courtesy of the Mirkin Group, Northwestern University.