Two Step Nanohole Fabrication Using FIB, EM and AFM

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Two Step Nanohole Fabrication Using FIB, EM and
AFM
Presented in The 6th International Conference
on Frontiers of Design and Manufacturing

• Dr. Jack G. Zhou
• Department of Mechanical Engineering and
  Mechanics
• Dr. Guoliang Yang
• Department of Physics
• Drexel University
• 3141 Chestnut Street
• Philadelphia, PA 19104

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Existing Approaches in Nano-fabrication

• Bottom up Approaches
• It is also called, Molecular manufacturing,
  molecular building blocks automatically link
  together to form desired nano-structures by means
  of self-assembly and self-organization
• Top down Approaches
• Generally these techniques are miniaturization
  of lithography, by using electron beam, focused
  ion beam, x-ray, deep UV, proximity probes etc .
  These processes conserve the lithography printing
  strategy.

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Basic Process Flow in Micromachining
Yong Chen and Anne Pepin Nanofabrication
Conventional and nonconventional
methods Electrophoresis 2001,22,187-207
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STM AFM
G. Binnig, H. Roher, C. Gerber and E. Weibel,
Surface Studied by Scanning Tunneling Microscopy,
Phys. Rev. Lett. 49, 57 (1982), G. Binnig, C.
Quate, and C. Gerber, Atomic Force Microscope,
Phys. Rev. Lett. 12, 930 (1986)
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Atomic Force Microscope (AFM)
C. Bustamate, D. Keller and G. Yang, Scanning
Force Microscopy of Nucleic Acids and
Nucleoprotein Assemblies", Curr. Opin. Struct.
Bio., 3, 363(1993).
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Atomic Force Microscope in our Lab
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AFM Cantilevers and Tips
100 mm
5 mm
500 nm
D. Keller and C. Chou, Imaging Steep, High
Structures by Scanning Force Microscopy with
Electron Beam Deposited Tip, Surf. Sci., 268,
333-339(1992)
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Proximal Probe Nano-lithography
T.Yasuda, S.Yamasaki and S. Gwo, Nanoscale
selective-area epitaxial growth of Si Using
ultrathin SiO2/Si3Ni4 patterned by an atomic
force microscope Applied physics letter Vol.
77,No. 24, 11 Dec. 2000
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Focused Ion Beam (FIB)
U. Dotsch and A.D. wieck Nanodevices produced
with focused ion beam Nuclear instruments and
methods in physics research B 139(1998) 12-19
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FIB Nano-lithography
Kenji Gamo Nanofabrication by FIB Microelectronic
Engineering 32(1996) 159-171
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Nanoimprint lithography
L.J. Heyderman etc. Flow behaviour of thin
polymer films used for hot embossing
lithography Microelectronic engineering 54(2000)
229-245
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Structures Made by Nano-imprint
Metal air-bridge
Metal T-gates
Mingtao Li, Lei Chen, and Stephen Y. Chou Direct
three-dimensional patterning using nanoimprint
lithography Applied physics letters, vol. 78
No.21, 21May 2001
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Why Nano-scale Holes?

• Nano-scale hole is one of the most basic, but
• very useful features
• Two nm nano-holes can be used in DNA sequencing
• Holder to fix a carbon nano-tube on an AFM probe
• Array of nano-holes as a mesh to screen
  nano-particles
• Nozzle in precision drug delivery
• Nano-mold to form nano-structures
• Easy to fabricate
• Simple structure to make other nanoscale
  features

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DNA sequencing
Microsecond Time-Scale Discrimination Among
Polycytidylic Acid, Polyadenylic Acid, and
Polyuridylic Acid as Homopolymers or as Segments
Within Single RNA Molecules By Mark Akeson, D.
Branton, J. Kasianowicz, E. Brandin, and D.
Deamer In Biophysical Journal Volume 77 December
1999 32273233
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Nanoholes used as mold
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New Method to Make Nano-scale Holes
Step1 Preparation of free standing nanoscale
thin film
Step2 Making sub-micro holes (.2 mm to .02mm)
with FIB, femtosecond laser, AFM, EB,
Step3 Reducing the hole to nanoscale, Less Than
20 nm,by epitaxial depostion, E-beam induced
deposition, micro coating, FIB deposition,
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Preparation of silicon epitaxial free standing
thin film

• Epitaxial deposition of n-Si thin film
• Patterning and developing
• Electrochemical etching

-
V
P-Si
OH-
OH-
Electrode
Epitaxial n-Si
Nadim Maluf An introduction to microelectromechani
cal systems engineering Boston Artech House,
c2000.
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Preparation of free standing thin film via
microfabrication
Square opening
D
h
Si3N4
H
Si
54.7?
Si3N4
d
111 direction
The size of the (square) free standing film d
D-2H/tan(54.7º) The size of the (square) hole in
the mask D d 2H/tan(54.7º)
Anisotropic Itching
Si3N4
Si
Si3N4
Free-standing film
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Sub-micron Micromachining Using Femtosecond Laser
Ta2O5-grating made with a single laser pulse
(248 nm, 0.5 ps, 100 mJ/cm2, vacuum).
Ta2O5-grating made with 2 laser pulses (248 nm,
0.5 ps, 300 mJ/cm2, vacuum).
F. Beinhorn , J. Ihlemann etc. Sub-micron grating
formation in Ta O wave guides by 2 5
femtosecond UV-laser ablation Applied Surface
Science 138139 1999 107110
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Epitaxial Deposition to Reduce the Size of an
Existing Hole
(2)Sub-micron hole made by FIB, femtosecond
laser, AFM, or EB
(1)Free-standing film Prepared by
Electrochemical etching
(3)Reduced nanohole By epitaxial deposition, EB
induced Deposition, thermo-assisted shrinkage
(4) Removing silicon nitride mask
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Our Microfabricated Silicon Nitride Free-Standing
Film
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Hole-Punch by Using AFM Probe
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Nanoholes Fabricated by FIB
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Nanoholes Made by Dual-Beam Focused Ion Beam
Instrument at Upenn
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Reduction of the Hole Size Using Electron Beam or
FIB Deposition
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Future work

• To use FIB or EB induced deposition to shrink
  nanoholes to single digit nanoholes.
• To make sub-micron holes by using AFM probe with
  a EB deposited nano pin as a tip.
• To mount nanotube on the AFM probe as a puncher
  to make single digit nonaholes directly.