Edge profile of relief 2D domains at the free surface of smectic copolymer thin films

Maaloum, Mounir; Ausserré, Dominique; Chatenay, D.; Coulon, G.; Gallot, Yves

doi:10.1103/physrevlett.68.1575

Cited by 81 publications

(67 citation statements)

References 12 publications

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“…17,18 The height of these islands or holes, as determined by AFM, provided another measure of L. Since the DSIMS and AFM results agree within 20 Å, the average of the two determinations is listed in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Confinement of Block Copolymers on Patterned Surfaces

Li¹,

Qu²,

Rafailovich³

et al. 1997

Macromolecules

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Smectic ordered films of the copolymer PS-P2VP were studied on periodic silicon surfaces (surface gratings). The modulation of the film surface with respect to that of the underlying substrate was found to be either in phase (conformal) orssurprisinglysout of phase (anticonformal). The critical height of the surface grating which is defined by the transition from conformal behavior to the anticonformal conformation of the films was found to be proportional to the lamellar height of the diblock copolymers. This has been quantitatively understood within a mean field theory as a result of balancing the deformation and interfacial energies. Furthermore, diblock copolymer films propagate the substrate roughness by significantly larger distances than observed for amorphous homopolymers.

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Section: Methodsmentioning

confidence: 99%

Confinement of Block Copolymers on Patterned Surfaces

Li¹,

Qu²,

Rafailovich³

et al. 1997

Macromolecules

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show abstract

“…Initially, islands and holes form randomly over the sample surface by a process analogous to spinodal decomposition [153,154]. Typically, the average size of the islands increases through coalescence of smaller domains and the growth of larger domains at the expense of smaller ones through an Ostwald ripening process [155][156][157][158][159][160][161][162]. This coarsening is driven by the line tension of the edges of the two-dimensional islands so that over time there is a decrease in the total length of island edges.…”

Section: Thicker Films and Bulk Order Evolutionmentioning

confidence: 99%

Patterning with block copolymer thin films

Segalman

2005

Materials Science and Engineering: R: Reports

927

918

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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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“…Ausserréet al 5 initially argued that the bilayer should exist one monolayer below the air surface, rather than on top as in Figure 1. Furthermore, they suggested that the lateral width of the step should be comparable to the bilayer thickness, L 0 , but AFM measurements by Maaloum et al 13 found the steps to be much broader. Using an elastic-distortion model developed by Pershan 14 for smectic-A liquid crystals, they were able to fit the surface profile of the steps.…”

Section: ■ Introductionmentioning

confidence: 99%

Step Edges in Thin Films of Lamellar-Forming Diblock Copolymer

et al. 2012

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Self-consistent field theory (SCFT) is used to study the step edges that occur in thin films of lamellar-forming diblock copolymer, when the surfaces each have an affinity for one of the polymer components. We examine film morphologies consisting of a stack of ν continuous monolayers and one semi-infinite bilayer, the edge of which creates the step. The line tension of each step morphology is evaluated and phase diagrams are constructed showing the conditions under which the various morphologies are stable. The predicted behavior is then compared to experiment. Interestingly, our atomic force microscopy (AFM) images of terraced films reveal a distinct change in the character of the steps with increasing ν, which is qualitatively consistent with our SCFT phase diagrams. Direct quantitative comparisons are not possible because the SCFT is not yet able to probe the large polymer/air surface tensions characteristic of experiment. ■ INTRODUCTIONThe behavior of block copolymer melts on solid substrates has received considerable attention over the last two decades motivated by a wide range of applications. 1−3 Not surprisingly, the earliest work 4−8 involved the simplest conceivable system, thin films of symmetric AB diblock copolymer on flat substrates. In the bulk, symmetric diblock copolymer forms a lamellar phase of alternating A-and B-rich domains, where each period, L 0 , consists of two monolayers. The main effect of confining the diblock copolymer to a thin film is to orient the domains. When the substrate and air surfaces of the film each have an affinity for one of the polymer components, the lamellae orient in the plane of the film, thereby forming a parallel lamellar (L ν ∥ ) phase consisting of ν diblock monolayers. Because of the strong tendency to maintain the preferred domain size of the bulk, the film height is quantized, H ≈ L 0 ν/ 2. Even values of ν are selected when the two surfaces have an affinity for the same component, and odd values occur when the two surfaces have opposite affinities. Usually the amount of material cast on the substrate is incommensurate with the preferred domain size, which leads to macrophase separation into thin and thick regions (i.e., terraces) separated by steps of height L 0 . The topography of the air surface changes from islands to a bicontinuous network to holes as the area of the thicker region increases. 4 The behavior becomes particularly interesting with the formation of elaborate terraced structures, when droplets 9−11 or rings 12 of diblock copolymer are deposited on the substrate.The presence of step edges separating different film thicknesses is ubiquitous in block copolymer films, and yet they have received relatively little theoretical attention. A step edge between the L ν ∥ and L ν+2 ∥ phases will typically involve ν continuous monolayers plus one semi-infinite bilayer as depicted schematically in Figure 1. Ausserréet al. 5 initially argued that the bilayer should exist one monolayer below the air surface, rather than on top as in Figure 1. Fu...

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Edge profile of relief 2D domains at the free surface of smectic copolymer thin films

Cited by 81 publications

References 12 publications

Confinement of Block Copolymers on Patterned Surfaces

Confinement of Block Copolymers on Patterned Surfaces

Patterning with block copolymer thin films

Step Edges in Thin Films of Lamellar-Forming Diblock Copolymer

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