Tools to Make Tools to Make NanostructuresNanostructures

“the challenge to Moore’s Law““the challenge to Moore’s Law“ Scanning Probe InstrumentsScanning Probe Instruments LithographyLithography

NanoscaleNanoscale Dip PenDip Pen E-BeamE-Beam Nanosphere LiftoffNanosphere Liftoff

Molecular SynthesisMolecular SynthesisSelf AssemblySelf AssemblyNanoscale Crystal GrowthNanoscale Crystal GrowthPolymerizationPolymerizationNanobricksNanobricksNanoCADNanoCAD

The Return of Scanning Probe The Return of Scanning Probe InstrumentsInstruments

Assembling materials Assembling materials atom-by- atom or atom-by- atom or molecule-by-molecule-by-moleculemolecule

Analogy – Analogy – “bulldozer” or “bulldozer” or “crane” or “backhoe”“crane” or “backhoe”

Elegant but slow and Elegant but slow and expensiveexpensive

http://www.aip.org/mgr/png/html/abacus.htmhttp://www.aip.org/mgr/png/html/abacus.htm

•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.)

Nanoscale LithographyNanoscale Lithography ““silk screen or rubber silk screen or rubber

stamp concept”stamp concept” Micro-imprint Micro-imprint

lithography developed lithography developed by George Whitesides by George Whitesides (Harvard)(Harvard)

- Pattern inscribed onto a Pattern inscribed onto a rubber surface rubber surface (silicon/oxygen polymer) (silicon/oxygen polymer) and the rubber surface is and the rubber surface is coated with molecular inkcoated with molecular ink

Complex but Complex but inexpensive and can inexpensive and can make numerous copiesmake numerous copies

Figure 15. Two examples of imprinting over a planarized surface.

http://www.molecularimprints.com/NewsEvents/tech_articles/new_articles/MOT_SPIE2003_Imprint_Lith_review_paper.pdf

Dip Pen LithographyDip Pen Lithography ““fountain pen analogy”fountain pen analogy” Developed by Chad Developed by Chad

Mirkin at Northwestern Mirkin at Northwestern Univ.Univ.

AFM tips are ideal AFM tips are ideal nanopensnanopens

Almost anything can be Almost anything can be used as nanoink used as nanoink

almost any surface can almost any surface can be written onbe written on

Almost anystructure can Almost anystructure can be made no matter how be made no matter how detailed or complexdetailed or complex

Dip-Pen Nanolithography: Transport of Dip-Pen Nanolithography: Transport of molecules to the surface via water meniscus.molecules to the surface via water meniscus.

                                                                                                                                                    

                                                                                                                                                                                       

http://chemgroups.northwestern.edu/mirkingroup/dpn.htm

A) 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

E-Beam LithographyE-Beam Lithography Use of electron Use of electron

beam to make beam to make structures at structures at nanoscalenanoscale

Applications in Applications in microelectronicsmicroelectronics

http://brainsturbator.com/pdf/Prentice%20Hall%20Ptrhttp://brainsturbator.com/pdf/Prentice%20Hall%20Ptr%20%20Nanotechnology%20A%20Gentle%20Introduction%20%20Nanotechnology%20A%20Gentle%20Introduction%20To%20The%20Next%20Big%20Idea.pdf%20To%20The%20Next%20Big%20Idea.pdf

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.

Nanosphere Liftoff Nanosphere Liftoff LithographyLithography

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

http://brainsturbator.com/pdf/Prentice%20Hall%20Ptr%20-%20Nanotechnology%20A%20Gentle%20Introduction%20To%20The%20Next%20Big%20Idea.pdf

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

http://www.sigmaaldrich.com/img/assets/3760/Acta_37_2.pdf

Self AssemblySelf Assembly Making nanostructures by Making nanostructures by

letting the molecules sort letting the molecules sort themselves outthemselves out

Molecules will always seek Molecules will always seek the lowest energy available the lowest energy available to themto them

Molecules will align Molecules will align themselves into particular themselves into particular positionspositions

Use for large nanoscale Use for large nanoscale arrays, different length arrays, different length scales, low cost, generalityscales, low cost, generality

Electronic applications, Electronic applications, coatingscoatings

http://brainsturbator.com/pdf/Prentice%20Hall%20Ptr%20%20Nanotechnology%20A%20Gentle%20Introduction%20To%20The%20Nexthttp://brainsturbator.com/pdf/Prentice%20Hall%20Ptr%20%20Nanotechnology%20A%20Gentle%20Introduction%20To%20The%20Next%20Big%20Idea.pdf%20Big%20Idea.pdf

Figure 4.6. Molecular model (top) of a self-assembled"mushroom" (more correctly a rodcoil polymer). Thephotograph (bottom) shows control of surface wetting by alayer of these mushrooms.Courtesy of the Stupp Group, Northwestern University.

Nanoscale Crystal Nanoscale Crystal GrowthGrowth

““seed crystal seed crystal concept”concept”

Silicon BoulesSilicon Boules Manipulating seed Manipulating seed

crystals to grow to crystals to grow to unusual shapesunusual shapes

Charles Lieber Charles Lieber (Harvard)(Harvard)

http://brainsturbator.com/pdf/Prentice%20Hall%20Ptr%20%20Nanotechnology%20A%20Gentle%20Introductionhttp://brainsturbator.com/pdf/Prentice%20Hall%20Ptr%20%20Nanotechnology%20A%20Gentle%20Introduction%20To%20The%20Next%20Big%20Idea.pdf%20To%20The%20Next%20Big%20Idea.pdf

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.

PolymerizationPolymerization Controlled polymerizationControlled polymerization, ,

in which one monomer at a in which one monomer at a time is added to the next, time is added to the next, is very important for is very important for specific elegant structures. specific elegant structures.

Robert Letsinger and his Robert Letsinger and his students at Northwestern students at Northwestern University have developed University have developed a series of methods for a series of methods for preparing specific short preparing specific short DNA fragments. These are DNA fragments. These are called called oligonucleotides. oligonucleotides.

The so-called gene The so-called gene machines use elegant machines use elegant reaction chemistry to reaction chemistry to construct specific DNA construct specific DNA sequences.sequences.

Figure 4.8. Schematic of the DNA hybridization process. The"matched" side shows how a DNA strand correctly binds to itscomplement and the "mismatched" side shows how errors canprevent binding.Courtesy of the Mirkin Group, Northwestern University.