Self-Diffusion of Asymmetric Diblock Copolymers with a Spherical Domain Structure

Yokoyama, Haruki; Krämer, Edward J.

doi:10.1021/ma9805250

Cited by 94 publications

(149 citation statements)

References 26 publications

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“…In the case of lamellar, cylindrical, and gyroid domains, diffusion along an interface occurs by a different mechanism than that perpendicular to the interface. In the perpendicular case as well as in diffusion between spherical nanodomains, the diffusion coefficient is D $ D 0 exp(axN min ), where N min is the shorter of the two blocks [149][150][151][152]. At lower temperatures, the polymer may not diffuse fast enough to allow rearrangement of domains into a structure with long-range order.…”

Section: Thicker Films and Bulk Order Evolutionmentioning

confidence: 99%

Patterning with block copolymer thin films

Segalman

2005

Materials Science and Engineering: R: Reports

929

921

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The nanometer-scale architectures in thin films of self-assembling block copolymers have inspired a variety of new applications. For example, the uniformly sized and shaped nanodomains formed in the films have been used for nanolithography, nanoparticle synthesis, and high-density information storage media. Imperative to all of these applications, however, is a high degree of control over orientation of the nanodomains relative to the surface of the film as well as control over order in the plane of the film. Induced fields including electric, shear, and surface fields have been demonstrated to influence orientation. Both heteroepitaxy and graphoepitaxy can induce positional order on the nanodomains in the plane of the film. This article will briefly review a variety of mechanisms for gaining control over block copolymer order as well as many of the applications of these materials. Particular attention is paid to the potential of perfecting long-range two-dimensional order over a broader range of length scales and the extension of these concepts to functional materials and more complex architectures. #

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Section: Thicker Films and Bulk Order Evolutionmentioning

confidence: 99%

Patterning with block copolymer thin films

Segalman

2005

Materials Science and Engineering: R: Reports

929

921

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“…Thus we come to a system of equations (13,27,28,30,31). Exact solution of this system is not trivial, so we will look only on large and small time asymptotics.…”

Section: Spreading Of the Copolymer Filmsmentioning

confidence: 99%

Spreading of block copolymer films and domain alignment at moving terrace steps

Белый

Witten

2004

The Journal of Chemical Physics

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We investigate spreading of phase separated copolymer films, where domain walls and thickness steps influence polymer flow. We show that at early stages of spreading its rate is determined by slow activated flow at terrace steps (i.e. thickness steps). At late stages of spreading, on the other hand, the rate is determined by the flow along terraces, with diffusion-like time dependence t −1/2 . This dependence is similar to de Gennes and Cazabat's prediction for generic layered liquids 1 , as opposed to the classical Tanner's law of drop spreading. We also argue that chain hopping at the spreading terrace steps should lead to the formation of aligned, defect-free domain patterns on the growing terraces.

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“…is the Rouse-model diffusion constant, [36] a is a parameter of order 1, [30,37] N A is the degree of polymerization of the core block (cylinders) or the longest block (lamellar), [30] and f is the monomeric friction factor. In our mate- [38] (both have a similar PMMA content, see Experimental).…”

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confidence: 99%

Induced Orientational Order in Symmetric Diblock Copolymer Thin Films

Sandstrom²,

2007

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Block-copolymer self-assembly has proven to be an attractive fabrication method for nanotechnology applications because of its ability to precisely define regular patterns with dimensions in the range of 10 to 100 nm. [1,2] Thin films of cylindrical and spherical patterns have been successfully used as lithographic templates in electronics applications [3][4][5][6][7][8] that require an optimal mask profile along with a minimum number of defects. Thin films of lamellar diblock copolymers have an advantageous profile for lithographic applications involving striped patterns; [2,9,10] however, their coarsening dynamics (i.e., pattern-forming properties) have not been as fully characterized as those of their asymmetric counterparts, [11][12][13] and their utility is not yet demonstrated.In this Communication we present a new polymer multilayer fabrication method -analogous to heteroepitaxial film growth -employing thin films of lamellar polystyrene-blockpoly(methyl methacrylate) (PS-b-PMMA). We also demonstrate the effectiveness of the technique by patterning silicon wire arrays with a 20 nm width and a 35 nm center-to-center spacing. In understanding the pattern-formation properties of lamellar-phase PS-b-PMMA, we find that orientational correlations in symmetric (lamellar) thin films evolve much more slowly with time than in asymmetric (cylindrical) films, limiting their use in applications that require long-range orientational order. To overcome this limitation, we demonstrate a multilayer pattern-formation process that features defect-free lamellar pattern formation.Diblock copolymer thin films of cylindrical and lamellar phases both form striped patterns that coarsen with annealing time (t) according to the power law n(t) ∼ t f , [14,15] where n is a correlation length associated with grain size, and f is termed the growth exponent. Striped patterns form from parallel oriented cylindrical-phase films and perpendicular lamellar domain orientations. Considerable previous theoretical work has described both the formation and evolution of generalized striped patterns [16][17][18] as well as two-dimensional lamellar block copolymers, [19][20][21][22][23] with predictions for f ranging from 0.2 to 0.5. Experimentally, Harrison et al. first measured the time evolution of n(t) in cylindrical phase PS-b-PI diblock copolymer thin-films, [24] finding a value for f of 0.25. Earlier experimental work by Garetz et al. [25] measured n in bulk lamellar diblock copolymers. From their data, one can estimate a value for f in the range of 0.066-0.131, i.e., significantly lower than f = 0.25. Despite their relevance in lithographic applications, correlations on thin films of symmetric diblock copolymers have been studied less. We prepared thin-film striped patterns of both parallel PSb-PMMA cylinders (Fig. 1a) and perpendicular PS-b-PMMA lamellae (Fig. 1b and c) to compare the time evolution of n. We spin-casted thin films of cylindrical and lamellar materials, and annealed them (195°C in vacuum) for times ranging from 5 to 4000 min...

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Self-Diffusion of Asymmetric Diblock Copolymers with a Spherical Domain Structure

Cited by 94 publications

References 26 publications

Patterning with block copolymer thin films

Patterning with block copolymer thin films

Spreading of block copolymer films and domain alignment at moving terrace steps

Induced Orientational Order in Symmetric Diblock Copolymer Thin Films

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