An Introduction to Dip-Pen Nanolithography

1
An Introduction to Dip-Pen Nanolithography
2
What is DPN?

• Direct-write patterning technique based on AFM
  scanning probe technology
• AFM tip is coated with ink and used to write on
  surface
• Very reliable bottom-up process (ink deposition
  rate can be precisely controlled)

Baselt, David. California Institute of
Technology. 1993. Images obtained at
lthttp//stm2.nrl.navy.mil/how-afm/how-afm.htmlgt
3
What is DPN? (continued)

• Compatible with both hard and soft matter on
  lengthscales below 100 nm
• Capable of depositing arrays of biomolecules on
  various materials (metals, semiconductors,
  functionalized surfaces)
• Biomolecules can be directly deposited on the
  surface in ambient temperature, no exposure to
  etchants, electron beams, or radiation

4
Advantages of DPN

• Resolution - 15nm
• Direct write so only where you want and what you
  want
• Based on AFM - can write and see
• Ambient conditions
• Image from J. Haaheim et al. Ultramicroscopy 103
  (2005) 122

5
Advantages continued

• More than one layer
• Can work with multiple inks at once
• Organic and inorganic inks
• Bottom-up and top-down

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Ink Theory

• Inks small organic molecules, organic and
  biological polymers, colloidal particles, metals
  ions

C. A. Mirkin et al, Angew. Chem. Int. Ed. 2004,
32.
7
Ink Theory (continued)

• Ink-substrate combinations
• Tip-substrate molecular transport
• Chemical makeup and purity (ink and surface)
• Shape of tip
• Distribution of ink on tip
• Temperature
• Humidity of surroundings
• Solubility of ink

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Ink Theory (continued)

• Water meniscus from ambient moisture
• Humidity controlled box

Modeled after the diagram in R.D. Piner, J. Zhu,
F. Xu, S. H. Hong, C. A. Mirkin, Science 1999,
283, 661.
9
Current Applications

• DPN is specially advantageous to biomolecular
  manipulation
• DNA and protein arrays are being fabricated as
  detection chips
• DPN resolution is four to five orders of
  magnitude greater than other lithographic
  techniques ultra-high density nanoarrays

Image courtesy of Oak Ridge National Laboratory.
Obtained at lthttp//homer.hsr.ornl.gov/CBPS/Array
technology/ZFChipSM.jpggt
10
Obstacles

• Most are currently being addressed
• Speed
• Matching inks to substrates, correct conditions
• Smooth surfaces to work on
• Turning the write head on/off at will

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Future Applications

• Parallel arrays
• Passive probe array
• Duplicate a pattern multiple times
• Independent control of each probe tip
• Create complex arrays at high speeds
• Automated tip coating and ink delivery
• Microfluidic technology possible ink wells for
  dipping of probe tip

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Sources

• C. A. Mirkin et al, Angew. Chem. Int. Ed. 2004,
  43, 30-45.
• Baselt, David. California Institute of
  Technology. 1993. Images obtained at
  http//stm2.nrl.navy.mil/how-afm/how-afm.html
• J. Haaheim et al. Ultramicroscopy 103 (2005) 122
• Gerding, J. D. et al. Journal of American
  Chemical Soc. 2005 127. 1106-1107.
• R.D. Piner, J. Zhu, F. Xu, S. H. Hong, C. A.
  Mirkin, Science 1999, 283, 661.
• Oak Ridge National Laboratory. http//homer.hsr.or
  nl.gov/CBPS/Arraytechnology/