Writing mesoscale patterns in block copolymer thin films through channel flow of a nonsolvent fluid

Pelletier, Vincent; Adamson, Douglas H.; Register, Richard A.; Chaikin, P. M.

doi:10.1063/1.2723673

Cited by 23 publications

(29 citation statements)

References 14 publications

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“…[ 37 ] The cylindrical microdomains of sheared BCP fi lms straightly aligned along the shear direction. [17][18][19][20] After solvent annealing, solvent evaporation occurs in the depth direction of the fi lm and a concentration gradient also is established within the fi lm, which can be a driving force for perpendicular orientation. In this situation, the PVAc/BCP region can form a perpendicular orientation owing to a signifi cantly reduced interfacial tension difference from 20. , while the dewetted region maintains a straightly parallel orientation of microdomains.…”

Section: Resultsmentioning

confidence: 99%

“…[ 9 ] The directionality of BCP patterns can also be controlled by graphoepitaxy from the sidewalls, [10][11][12][13] epitaxy from chemical and topographical patterns, [14][15][16] and shear-induced alignments. [17][18][19][20] For sub-7 nm patterns, a particularly high Flory-Huggins interaction parameter ( χ ; degree of immiscibility) of BCP pairs should be used. While conventional polystyrene-blockpoly(methyl methacrylate) (PS-b -PMMA) has a χ value of 0.03 at 25 °C and cannot phase-separate to smaller than 20 nm, [ 22 ] polydimethylsiloxane (PDMS) based BCPs can be formed with a sub-7 nm half-pitch of phase separation, such as PS-b -PDMS ( χ ≈ 0.14 at 25 °C) [22][23][24] or poly(2-vinyl pyridine)-b -PDMS.…”

Section: Introductionmentioning

confidence: 99%

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Topcoat‐Assisted Perpendicular and Straightly Parallel Coexisting Orientations of Block Copolymer Films

Jeong

Lee

et al. 2015

Macromol. Rapid Commun.

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Highly ordered perpendicular orientation and straightly parallel orientation coexisting polystyrene-block-polydimethylsiloxane (PS-b-PDMS) cylindrical microdomains with 10 nm width can be realized by using polyvinyl acetate as a partially dewetted topcoat and solvent annealing with acetone vapor. During solvent annealing, the swelled topcoat begins to dewet and the dewetting rim sweeps the surface of the block copolymer films to align the cylindrical microdomains with the direction of dewetting propagation. However, the wetted region of the topcoat/PS-b-PDMS film forms with a perpendicular orientation due to reduced surface tension and sufficient concentration gradient in the solvent evaporation step. The orientational changes (perpendicular/straightly parallel orientation) in the dewetted/wetted area are also investigated according to the vapor pressure of solvent annealing. The degree of directionality of the swept PS-b-PDMS films according to the distance from the dewetting front, which is equivalent with time after sweeping, is examined. To control the direction of dewetting and complex structures within a specific area, an imprinting process is introduced to form topographical line-space patterns in the topcoat and perpendicular/parallel orientation of BCP patterns in the line-space patterns, respectively.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Topcoat‐Assisted Perpendicular and Straightly Parallel Coexisting Orientations of Block Copolymer Films

Jeong

Lee

et al. 2015

Macromol. Rapid Commun.

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“…Using a shearing field to orient the microdomains is an attractive technique because of the ease of orienting a large area (on the order of square centimeters) rapidly and for its simplicity and low cost. Previous work has shown the effectiveness of shear alignment for monolayers of cylinder-forming polymers [10][11][12] and bi-or multilayers of sphere-forming polymers, which form a hexagonal in-plane arrangement of spheres [12][13][14][15]. A representative example of the effectiveness of shear is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Orientational order in cylinder-forming block copolymer thin films

Marencic

Chaikin

2012

Phys. Rev. E

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Shear can impart a high degree of orientational order to supported block copolymer thin films containing one or more layers of cylindrical microdomains, leading to a striped pattern with a period of tens of nanometers extending over macroscopic (centimeter-squared) areas. Though the as-deposited films have a polygrain structure, after shearing at sufficiently high stresses the only defects which remain are isolated dislocations, and the orientational order can be quite high (nematic or twofold orientational order parameter >0.99, as measured by tapping-mode atomic force microscopy). The effect of isolated dislocations on orientational order is adequately captured by an isotropic elastic continuum model of the structure surrounding the dislocation, producing a linear decrease of order parameter with dislocation density. Even at zero dislocation density, however, the order parameter does not quite reach unity, due to small-amplitude undulations of the cylinders about their axes which persist in the transverse direction over several cylinder periods.

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“…Therefore, it is very important to control the local defects of self-assembled polymer patterns with the application of these materials. As the efforts to rectify this, many researches and techniques such as electric fields [20], flow [21], shear application [22][23][24], thermal treatment [25], chemically pre-patterned surface (chemoepitaxy) [26,27], and topographical confinement (graphoepitaxy) [28] have been carried out to reduce the defect density in specific pattern-forming block copolymer thin films. Among the controlling method, authors in [19] proposed an appropriate substrate design and achieved a defect-free pattern formation.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of local defectiveness control of diblock copolymer patterns

Jeong¹,

Choi²,

Kim³

2016

Condens. Matter Phys.

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We numerically investigate local defectiveness control of self-assembled diblock copolymer patterns through appropriate substrate design. We use a nonlocal Cahn-Hilliard (CH) equation for the phase separation dynamics of diblock copolymers. We discretize the nonlocal CH equation by an unconditionally stable finite difference scheme on a tapered trench design and, in particular, we use Dirichlet, Neumann, and periodic boundary conditions. The value at the Dirichlet boundary comes from an energy-minimizing equilibrium lamellar profile. We solve the resulting discrete equations using a Gauss-Seidel iterative method. We perform various numerical experiments such as effects of channel width, channel length, and angle on the phase separation dynamics. The simulation results are consistent with the previous experimental observations.

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Writing mesoscale patterns in block copolymer thin films through channel flow of a nonsolvent fluid

Cited by 23 publications

References 14 publications

Topcoat‐Assisted Perpendicular and Straightly Parallel Coexisting Orientations of Block Copolymer Films

Topcoat‐Assisted Perpendicular and Straightly Parallel Coexisting Orientations of Block Copolymer Films

Orientational order in cylinder-forming block copolymer thin films

Numerical investigation of local defectiveness control of diblock copolymer patterns

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