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© 2010 IBM Corporation
Introduction to / Status of Directed Self- Assembly
DSA Workshop, Kobe Japan, October 2010
Bill Hinsberg
IBM Almaden
Research CenterSan Jose CA 95120
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 20102
from “Bringing New Materials to Market,” ,TW Eagar, Technology Review Feb/Mar 1995, p 43
Poor communication between inventors and product designers
Inadequate/immature materials supply and production capacity
Inadequate economic incentives for user or supplier
Inflexible codes and standards
The commercialization of new materials technologies is slowed by
Twenty years from invention to commercialization…Materials Technology Date of Invention Widespread commercializationVulcanized rubber 1839 Late 1850s
Low cost aluminum 1886 Early 1900s
Teflon 1938 Early 1960s
Titanium as a structural mat’l. Mid 1940s Mid 1960s
Velcro Early1950s Early 1970s
Poly(carbonate) 1953 ~ 1970
Gallium arsenide mid 1960s Mid 1980s
Diamond-like carbon films Early 1970s Early 1990s
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 20103
Outline
What is Self-assembly?What is Directed
Self-assembly?
My assessment of –Current status
–Near-term and mid-term needs
–What might a first application of DSA look like
–What might a 2nd
generation application of DSA be?
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 20104
Self-assemblySpontaneous, reversible transformation of a disorganized system into regular structures or patterns
Controlled by weak interactions (van der
Waals, capillary, π − π, hydrogen bonds)
Molecular properties are important
Outcome typically controlled by thermodynamic equilibria
dimensions controlled by molecular size, magnitude of weak interactions
in contrast to microlithography…Transfer of an existing pattern into a recording medium
Controlled by strong forces (covalent bond formation/fragmentation
Properties of specific bonds are important
Outcome typically controlled by kinetics
dimensions controlled by length scales of energy deposition and kinetic processes
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 20105
Biological / bio-inspired –
assembly using biomolecules
(DNA, proteins, phage-virus)
–
nanomedicine, devices, structural materials
Polymer –
block copolymers, phase separated polymers–
patterning, structured materials
Layer-by-layer –
Self-assembled monolayers–
sequential deposition of alternating layers–
bio/medical, sensors, optical devices, solar cells
Nanoparticle–
assembly can be mediated by small molecules, biomolecules, polymers, topography
–
magnetic composites, electronic devices, catalysis
DNA nanostructures
(N. Seeman / NYU)
Templated
assembly (Xia/ U Washington)
Ultrastrong
polymer
composites (Kotov/UM)
“knitting pattern”
in ABC triblock
copolymer
(Stadler/Gutenberg U)
Taxonomy of self-assembly
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 20106
Block copolymer self-assembly
Block copolymers in wide commercial use (e.g. adhesives, coatings)
repulsion between dissimilar polymer chains drives microphase
separation
Pros : sublithographic
patterns, high feature density, dimensions controlled by chemical synthesis
Cons: limited pattern types, random orientation, poor long-range order
Poly-A
Poly-B
where χ
= interaction parameter
even slightly unfavorable interactioncauses phase separation
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 20107
Directed
Block copolymer self-assembly
Bottom-upSelf-assembling
material
Top-down Lithographically
patterned substrate
Limited spatial resolution
Large CD variation
+
High spatial resolution
No placement control
Directed Self- assembly
=
Enhanced resolution
Reduced CD variation
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 20108
Two approaches to orientation control
Segalman
et al, Adv. Mater., 13, 1152 (2001) Cheng et al, Appl. Phys. Lett., 81, 3657 (2002)Sundrani
et al., Nano Lett., 4, 273 (2004)
selective surface modification
neutral substrate surface
Rockford et al., Phys. Rev. Lett., 82, 2602 (1999)Kim et al., Nature, 424, 411 (2003)
On topographic patterns : graphoepitaxy
On surface patterns: chemical epitaxy
neutral substrate surface
neutral substrate surface
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 20109
BCP DSA on Topographical Patterns
DSA Subdividing the trench
Cross-barStructures
Via Shrink andrectification
DSA
DSA
Guiding Lines
Organosilicate
PS-b-PEO/MSSQ
DSA on 193 nm resist Wresist = 375nm, PSA =25nm
15X Subdivision
DSA
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 201010
BCP DSA on Chemical Patterns
80 nm
10
20
193 nm litho to form guide pattern
Apply BCP anneal and develop
Form trim mask by 193 nm litho,And dry etch to substrate
Strip
193 nm resist: 100 nm pitch
DSA: 25 nm pitch
NeutralizeLiftoffDSAEtch
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 201011
Attributes of BCP DSA
an adjunct/assist to conventional litho practice–Pattern subdivision process analogous to sidewall image transfer
– trim mask, single CD available–Via process shares analogous to chemical shrink processes (“smart”
shrink)
able to extend capabilities of current (and future) lithographic technologies–Sublithographic
dimensions, tighten dimensional tolerances, defect reduction
Not universally applicable
Characteristics of DSA must be accounted for early in design cycle
mask design must be “DSA-aware”
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 201012
Status of BCP DSA
Several process approaches have been demonstrated
compatibility with 193 nm lithographic materials established
compatible process times and coating solvents are demonstrated
PS-PMMA has been focus for process development
Staged for practical demonstrations
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 201013
Near term needs for BCP DSA…
Identification and specification of initial applications by end-users
detailed examination of integration issues
Chip-scale and wafer-scale characterization in a fab
environment of CD uniformity, placement accuracy, defects, LER
Mid term …
broadening scope of application
extendibility -
smaller dimensions
improved materials –
block copolymers, surface control layers, guide pattern materials
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 201014
Some candidates for first practical application of DSALamellar patterns
DSA
Multifingered
devices (Nanowire
arrays, FinFET)
Regularized patterns/gratings
Via shrink/rectification
Bit-patterned media
Cylindrical patterns
What else?
Specific target : dimensions, materials, insertion point
What are the benefits and shortcomings?
What still needs to happen to enable?
Keep in mind during the day
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 201015
Potential candidates for 2nd generation applications of DSA
Multiple levels of DSA : pattern-to-pattern alignment
Complex DSA patterns : bends, jogs, tees
Imageable
BCP films
Direct patterning of device structures
Specific targets
What else?
Advantages and issues
What still needs to happen to enable these?
Keep in mind during the day
Introduction to / Status of Directed Self-Assembly
Hinsberg / IBM Almaden Research Center DSA Workshop, Kobe Japan, October 201016
Today’s workshop
Broad spectrum of research will be described
Emphasis on BCP DSA but other forms of DSA are to be discussed
Diverse range of participants : research, tooling and materials suppliers, end-users offer a range of perspectives