Nanotechnology for engineers
Summer semester 2004-2005
SPM lithography
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Nanotechnology for Engineers : J. Brugger (LMIS-1) & P. Hoffmann (IOA)
Microfabricated tools for nanotechnologies
Surface modification using SPM
• the nature of the interaction determines the
sample
property that is observed
• the magnitude of the interaction determines
whether
we observe or modify: SPM as a microscope or
a tool
interaction
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Microfabricated tools for nanotechnologies
SPM Lithography
various interaction with sample
• high resolution (clearly sub-100nm)
• 3D capable (slight topography compensate with flexible beam)
• parallel approach (gain speed)
• examples:
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field enhanced oxidation
resist exposure
Dip-Pen/NADIS lithography (physico-chemical)
Scanning nanostencil
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Microfabricated tools for nanotechnologies
Nanostructures made by AFM probe
Compact Disc
1 µm
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Microfabricated tools for nanotechnologies
SPL (1) Field Enhanced Oxidation
Picture and text from:
Quate Group, Stanford
A voltage bias between a sharp probe tip and a sample generates an intense electric field at the tip. The high field
can be used to locally oxidize silicon in a process known as electric-field-enhanced oxidation. The high field desorbes
the hydrogen passivation on the silicon surface, allowing the exposed silicon to oxidize in air (the oxidation rate is
enhanced by the presence of the accelerating field). Both single-crystal silicon and amorphous silicon may be locally
oxidized in such a way. This local oxidation process is powerful because of its fine resolution (sub-50-nm) and the
resistant oxide etch mask that is created. Our work involves characterizing the oxidation process, increasing
pattering reliability and throughput, and fabricating structures and devices using this local oxidation technique.
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Microfabricated tools for nanotechnologies
SPL (1) Field Enhanced Oxidation with 50 levers in parallel
Oxidation of silicon with 50 probes.
Probes are spaced by 200 um and
each was used to draw a single
line 1 cm long. The full patterned
area spans 1 cm x 1 cm.
The blue box in the lower left
corner of the image depicts the
typical scan area of a commercial
AFM (100 um x 100 um).
From: Quate Group, Stanford
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Microfabricated tools for nanotechnologies
SPL (2) Exposure of resist
From: Quate Group, Stanford
Electron exposure of a resist
material, such as an organic
polymer or a monolayer resist using
field-emission from the tip (induce
chemical changes).
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Microfabricated tools for nanotechnologies
SPL (2) Exposure of resist (3D capable)
100-nm pMOSFET Fabrication Gate
Lithography
Uniform 100-nm Gate Over Topography
From: Quate Group, Stanford
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Microfabricated tools for nanotechnologies
Dip-Pen Nanolithography
Writing >30 nm lines on Au surface
using 1-othodecanethiol as ink
Chad A. Mirkin et al. Science 283, 661
(1999)
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Microfabricated tools for nanotechnologies
Nanoscale Dispensing
•
pattern “liquids”, e.g.
biomolecules, suspensions,
“surface chemistry”, ...
•
•
versatile (ambient conditions)
parallel probes for multi-material
deposition
integration of fluidic system
possible
•
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Microfabricated tools for nanotechnologies
Nanoscale Dispensing – FIBbed probes
material to deposit
probe with apertured tip
deposition of drops by touching
substrate
reservoir
2nd generation
probes prepared
by FIB milling
tip/apert. head-on
tip
1st approach:
no approach snap-in
indicating clean surface
array with 1.0 µm pitch,
drops separated
array with 0.5 µm pitch,
drops collapsed onto one
2nd & more approaches:
snap-in distance 100nm
corresp. to drop height
glycerol on SiO2, image size 10 µm x 10 µm
dots size 50 – 100 nm
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Microfabricated tools for nanotechnologies
Parallel Probe Dispensing
• Array of 4 cantilevers with
passivated aluminum
electrodes for
electrowetting
• Deposition of two
different solutions with
the same cantilevers
CNRS Toulouse
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Microfabricated tools for nanotechnologies
Parallel Dispensing
CNRS Toulouse
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Nanotechnology for engineers
Summer semester 2004-2005
AFM nanostencil
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Nanotechnology for Engineers : J. Brugger (LMIS-1) & P. Hoffmann (IOA)
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Microfabricated tools for nanotechnologies
Scanning AFM nanostencil
FIB modified AFM cantilever tip
A evaporation source
B light source
C light detector (PSD)
D cantilever
E sample
IBM Zurich Research Laboratory
Roli Luthi et al. APL 75, n. 9, 1999
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Microfabricated tools for nanotechnologies
Scanning AFM nanostencil
Unique feature: Variable thickness
as function of scan speed.
• Metal deposition
• Atomically clean
• Easy relocation
• AFM images and patterning with same cantilever
200 nm
90 nm
Cu nanowire
Cu nano-ring
width < 90 nm, height 4 nm
width < 200 nm, height 20 nm
R. Luthi et al. APL 75, n. 9, 1999
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