Introduction to / Status of Directed Self- Assembly

Transcription

1 Introduction to / Status of Directed Self- Assembly DSA Workshop, Kobe Japan, October 2010 Bill Hinsberg IBM Almaden Research Center San Jose CA hnsbrg@almaden.ibm.com 2010 IBM Corporation

2 from Bringing New Materials to Market,,TW Eagar, Technology Review Feb/Mar 1995, p 43 Twenty years from invention to commercialization Materials Technology Date of Invention Widespread commercialization Vulcanized 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 The commercialization of new materials technologies is slowed by 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 2

3 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 2 nd generation application of DSA be? 3

4 Self-assembly Introduction to / Status of Directed Self-Assembly Spontaneous, 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 4

5 Taxonomy of self-assembly Biological / bio-inspired assembly using biomolecules (DNA, proteins, phage-virus) nanomedicine, devices, structural materials DNA nanostructures (N. Seeman / NYU) 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 knitting pattern in ABC triblock copolymer (Stadler/Gutenberg U) Ultrastrong polymer composites (Kotov/UM) Nanoparticle assembly can be mediated by small molecules, biomolecules, polymers, topography magnetic composites, electronic devices, catalysis Templated assembly (Xia/ U Washington) 5

6 Block copolymer self-assembly Poly-A Poly-B 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 where χ = interaction parameter even slightly unfavorable interaction causes phase separation 6

7 Directed Block copolymer self-assembly Bottom-up Self-assembling material Top-down Lithographically patterned substrate Directed Selfassembly + = High spatial resolution No placement control Limited spatial resolution Large CD variation Enhanced resolution Reduced CD variation 7

8 Two approaches to orientation control On topographic patterns : graphoepitaxy On surface patterns: chemical epitaxy neutral substrate surface neutral substrate surface selective surface modification neutral substrate surface 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) Rockford et al., Phys. Rev. Lett., 82, 2602 (1999) Kim et al., Nature, 424, 411 (2003) 8

9 BCP DSA on Topographical Patterns Guiding Lines PS-b-PEO/MSSQ DSA Cross-bar Structures Organosilicate DSA Subdividing the trench DSA on 193 nm resist W resist = 375nm, P SA =25nm 15X Subdivision DSA Via Shrink and rectification DSA 9

10 BCP DSA on Chemical Patterns 80 nm 193 nm litho to form guide pattern Apply BCP anneal and develop 193 nm resist: 100 nm pitch Neutralize Liftoff DSA Etch Form trim mask by 193 nm litho, And dry etch to substrate DSA: 25 nm pitch Strip

11 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 11

12 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 12

13 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 13

14 Some candidates for first practical application of DSA Lamellar patterns Cylindrical patterns DSA Multifingered devices (Nanowire arrays, FinFET) Via shrink/rectification Regularized patterns/gratings Bit-patterned media Keep in mind during the day What else? Specific target : dimensions, materials, insertion point What are the benefits and shortcomings? What still needs to happen to enable? 14

15 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 Keep in mind during the day Specific targets What else? Advantages and issues What still needs to happen to enable these? 15

16 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 16