Block Copolymer Micelle Nanolithography Roman Glass, Martin Moller and Joachim P Spatz University of Heidelberg IOP Nanotechnology (2003)MotivationProcess OverviewDiblock Copolymer MicellesCluster Pattern CharacterizationGuided Self-Assembly (>250nm)Cluster AggregationLine PatterningNegative Patterning with E-beamMicelles on Electrically Insulating FilmsMechanical Stability of Nano-ClustersConclusionsBlock Copolymer Micelle NanolithographyRoman Glass, Martin Moller and Joachim P SpatzUniversity of HeidelbergIOP Nanotechnology (2003)Erika ParraEE2354/18/2007MotivationMarket TrendsSmall features Sub-10nm clusters depositedPatterns 50nm to 250nm and greaterLower cost of tedious fabrication processes for conventional lithographyIncrease throughput (from e-beam) – parallel processBottom line: bridge gap between traditional self-assembly and lithographyProcess OverviewDip wafer (Si) into micelle solution Retrieve at 12mm/minAir-evaporate solventPlasma (H2, Ar, or O2) removes polymer shellResults:UniformHexagonal2, 5, 6, or 8nmSphericalPS(190)-b-P[2VP(Au0.2)](190) PS(500)-b-P[2VP(Au0.5)](270)Side view TEM – treated waferPS(990)-b-P[2VP(Au0.5)](385) PS(1350)-b-P[2VP(Au0.5)](400)Au ~ HAuCl4Diblock Copolymer MicellesDendrite shaped macromoleculeCorona is amphiphilicMicelle MW and shape controlled by initial monomer concentrationPolymer 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 saltIn 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) AuP2VPPSCluster Pattern CharacterizationMW tunes nanodot distance (max of 200 nm micelle)Low polydispersity permits regularityHigher MW decreased pattern quality and position precision (softness in shell)Low PDIGuided Self-Assembly (>250nm)Predefine topographies using photo or e-beamSpin-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 micelles2nd plasma treatment removes micelle polymer (100W, 0.4mbar, 20min)PS(1350)-b-P[2VP(Au0.5)](400)D = 8nm, L = 85nmCluster AggregationVary PR thicknessFeature height (volume) defines cluster diameterFigure: e-beam 200nm features on 2um square lattice800nm500nm75nmLine PatterningCylindrical micelleFormed if corona volume fraction < corePS(80)-b-P2VP(330)Length of several micronsSubstrate patterned with grooves & dipped in micelle solution4nm lineNegative Patterning with E-beamSpin-on micellesExpose with e-beam (1KeV, 400-50,000 μC/cm2), 200um widthUltrasound bath + 30min plasmaElectrons stabilize micelle on Si due to carbon species formed during exposureMicelles on Electrically Insulating FilmsGlass substrate desired in biologyE-beam requires conductive substrateEvaporate 5nm carbon layerMechanical Stability of Nano-ClustersTreated and unaffected by:Pirahna, acids, many bases, alcohols, ultrasonic water bathHypothesis: edge formed by the substrate-cluster borderline is partly wetted by surface atoms during plasma treatment Thermal800 C evaporated clusters but no migration occuredConclusionsSimple process for sub-10nm clusters and linesBlock copolymer micelle size controls nano-cluster interspacingMicelle size controlled by monometer concentrationsF. Weigl et al. / Diamond & Related Materials 15 (2006)Micelles as masks for diamond field
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