Block Copolymer Micelle Nanolithography Roman Glass, Martin Moller and Joachim P Spatz University of Heidelberg IOP Nanotechnology (2003)

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Block Copolymer Micelle NanolithographyRoman
Glass, Martin Moller and Joachim P
SpatzUniversity of HeidelbergIOP Nanotechnology
(2003)

• Erika Parra
• EE235
• 4/18/2007

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Motivation

• Market Trends
• Small features
• Sub-10nm clusters deposited
• Patterns 50nm to 250nm and greater
• Lower cost of tedious fabrication processes for
  conventional lithography
• Increase throughput (from e-beam) parallel
  process
• Bottom line bridge gap between traditional
  self-assembly and lithography

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Process Overview

• Dip wafer (Si) into micelle solution
• Retrieve at 12mm/min
• Air-evaporate solvent
• Plasma (H2, Ar, or O2) removes polymer shell
• Results
• Uniform
• Hexagonal
• 2, 5, 6, or 8nm
• Spherical

PS(190)-b-P2VP(Au0.2)(190)
PS(500)-b-P2VP(Au0.5)(270)
PS(990)-b-P2VP(Au0.5)(385)
PS(1350)-b-P2VP(Au0.5)(400)
Side view TEM treated wafer
Au HAuCl4
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Diblock Copolymer Micelles

• Dendrite shaped macromolecule
• Corona is amphiphilic
• Micelle MW and shape controlled by initial
  monomer concentration
• Polymer corona with neutralized core (Au, Ag,
  AgOx, Pt, Pd, ZnOx, TiOx, Co, Ni, and FeOx)
• Nanodot core size is controlled by the amount
  of metal precursor salt

PS
P2VP
Au
In this paper Water-in-oil micelle (toulene
solvent) Polystyrene(x)-b-poly(2-vinylpyridine)(y)
(PS(x)-b-P2VP(y)) Au core from chloroauric
precursor (HAuCl4)
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Cluster Pattern Characterization
Low PDI

• MW tunes nanodot distance (max of 200 nm micelle)
• Low polydispersity permits regularity
• Higher MW decreased pattern quality and position
  precision (softness in shell)

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Guided Self-Assembly (gt250nm)

• Predefine topographies using photo or e-beam
• Spin-on concentrated micelle solution (capillary
  forces of evaporating solvent adheres them to
  sides)
• Micelles are pinned to the substrate by plasma
  (100W, 0.4mbar, 3min)
• Lift-off removes PR and micelles
• 2nd plasma treatment removes micelle polymer
  (100W, 0.4mbar, 20min)

PS(1350)-b-P2VP(Au0.5)(400) D 8nm, L 85nm
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Cluster Aggregation

• Vary PR thickness
• Feature height (volume) defines cluster diameter
• Figure e-beam 200nm features on 2um square
  lattice

800nm
500nm
75nm
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Line Patterning

• Cylindrical micelle
• Formed if corona volume fraction lt core
• PS(80)-b-P2VP(330)
• Length of several microns
• Substrate patterned with grooves dipped in
  micelle solution

4nm line
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Negative Patterning with E-beam

• Spin-on micelles
• Expose with e-beam (1KeV, 400-50,000 µC/cm2),
  200um width
• Ultrasound bath 30min plasma
• Electrons stabilize micelle on Si due to carbon
  species formed during exposure

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Micelles on Electrically Insulating Films

• Glass substrate desired in biology
• E-beam requires conductive substrate
• Evaporate 5nm carbon layer

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Mechanical Stability of Nano-Clusters

• Treated and unaffected by
• Pirahna, acids, many bases, alcohols, ultrasonic
  water bath
• Hypothesis edge formed by the substrate-cluster
  borderline is partly wetted by surface atoms
  during plasma treatment
• Thermal
• 800 C evaporated clusters but no migration
  occured

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Conclusions

• Simple process for sub-10nm clusters and lines
• Block copolymer micelle size controls
  nano-cluster interspacing
• Micelle size controlled by monometer
  concentrations

Micelles as masks for diamond field emitters
F. Weigl et al. / Diamond Related Materials 15
(2006)