Identifying the nature of surface chemical modification for directed self-assembly of block copolymers

Evangelio, Laura; Gramazio, Federico; Lorenzoni, Matteo; Gorgoi, Mihaela; Espinosa, Francisco M.; García, Ricardo García; Pérez‐Murano, F.; Fraxedas, Jordi

doi:10.3762/bjnano.8.198

Cited by 7 publications

(7 citation statements)

References 38 publications

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“…(See supplemental information, figure S1). Surface characterization of the brush layer reveals an increased affinity of the brush layer with respect to PMMA when it is exposed to oxygen plasma 30 and, under mild oxygen plasma conditions, a very low damage (See the AFM characterization of the chemically functionalized guiding patterns in the supplemental information, figure S1).…”

Section: Resultsmentioning

confidence: 99%

“…The most significant parameters are of dimensional nature (BCP film thickness, D, and guiding pattern dimensions), materials related (number of statistical segments per diblock copolymer, N, the statistical segment length, b, and the Flory-Huggins parameter, ) and process related (annealing temperature, solvent material, solution concentration and interface boundary energies). In addition to the here-referred parameters, the chemical interactions that take place between each domain of the BCP and the patterned surface (guiding and background stripes) is of prime importance as the main driving force in DSA by chemical epitaxy 30 . These interactions, in turn, are related to the difference of surface free energies of each copolymer domain and the confining boundary, Δ = SA -SB.…”

Section: Introductionmentioning

confidence: 99%

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Role of Penetrability into a Brush-Coated Surface in Directed Self-Assembly of Block Copolymers

Evangelio

Fernández-Regúlez

Fraxedas

et al. 2018

ACS Appl. Mater. Interfaces

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High density and high resolution line and space patterns on surfaces are obtained by directed selfassembly of lamella-forming block copolymers using wide-stripes chemical guiding patterns. When the width of the chemical pattern is larger than the half-pitch of the block copolymer, the interaction energy between each block copolymer domain and the surface is crucial to obtain the desired segregated film morphology. We investigate how the intermixing between block copolymers and polymer brush molecules at the surface influences the optimal surface and interface free energies to obtain a proper block copolymer alignment. We have found that computational models successfully predict the experimentally obtained guided patterns if the penetrability of the brush layer is taken into account instead of a hard, impenetrable surface. Experiments on directed self-assembly of lamella-forming PS-b-PMMA using chemical guiding patterns corroborate the models used in the simulations, where the values of the surface free energy between block copolymer and guiding and background stripes are accurately determined using an experimental method based on the characterization of contact angles in droplets formed after dewetting of homopolymer blends.to one of them, respectively. Therefore, a proper wetting balance of the polymer blocks to the substrate is needed to promote lamellae oriented perpendicular to the substrate. The most common way to control the orientation of the BCP micro-domains consists in using neutral surfaces to control the surface free energy, so that the difference in the surface interaction of the two blocks is small.. 9Thin films of vertical lamellae form patterns whose morphology is randomly oriented; the width of the lines being defined by the molecular weight of the BCP. Nevertheless, ordered arrays of lines with a predefined orientation and registered with respect to device boundaries are required for most of technological applications, not only for high volume manufacturing, but also as a general method to realize templates for anisotropic metal nanostructures 10 . This can be achieved by pre-structuring the substrate with guiding patterns of appropriate dimensions and shape. These guiding patterns are realized by grapho-or chemoepitaxy methods. In graphoepitaxy, [11][12][13] the guiding patterns are made of topographical features. Usually, the width of the trench becomes a limitation for achieving high density of integration. [14][15][16] Therefore, in order to avoid this limitation, chemical epitaxy methods have been intensively explored to produce highly dense patterns. 3,[17][18][19] Moreover, in chemical epitaxy there is a reduction of the edge roughness due to the self-healing of the BCP, which means that the irregularities of the guiding patterns are not transferred to the BCP pattern. 20 Chemical guiding patterns are fabricated by conventional topdown lithographic methods like optical, extreme ultraviolet (EUV) projection or electron beam lithography (EBL), in combination with a selective, local chemical...

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of Penetrability into a Brush-Coated Surface in Directed Self-Assembly of Block Copolymers

Evangelio

Fernández-Regúlez

Fraxedas

et al. 2018

ACS Appl. Mater. Interfaces

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“…Chemoepitaxy involves the creation of dense chemical patterns on a neutral substrate to generate preferential wetting sites for one of the blocks [ 57 ]. Multiple processes and techniques have been successfully used to selectively tune the surface free energy of a neutral surface, including photolithography [ 58 ], electron-beam lithography (EBL) and oxygen plasma functionalization [ 59 , 60 , 61 , 62 , 63 ], direct EBL exposure [ 64 ] and scanning-probe lithography [ 65 , 66 , 67 ].…”

Section: Principles Of the Dsa Of Block Copolymersmentioning

confidence: 99%

Directed Self-Assembly of Block Copolymers for the Fabrication of Functional Devices

et al. 2020

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Directed self-assembly of block copolymers is a bottom-up approach to nanofabrication that has attracted high interest in recent years due to its inherent simplicity, high throughput, low cost and potential for sub-10 nm resolution. In this paper, we review the main principles of directed self-assembly of block copolymers and give a brief overview of some of the most extended applications. We present a novel fabrication route based on the introduction of directed self-assembly of block copolymers as a patterning option for the fabrication of nanoelectromechanical systems. As a proof of concept, we demonstrate the fabrication of suspended silicon membranes clamped by dense arrays of single-crystal silicon nanowires of sub-10 nm diameter. Resulting devices can be further developed for building up high-sensitive mass sensors based on nanomechanical resonators.

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“…Colloidal assembly is one of important routes to manufacture products with great diversities and functionalities in various applications, such as photonic crystals [1,2], soft lithography templates [3], and anti-reflection film [4]. There are ways of acquiring desired structures by colloidal assembly based on electrical controlling [5], optical trapping [6], capillarity [7], and chemical modification [8]. The final macroscopic structures assembled from colloidal particles by these methods greatly depends on the dynamic driving forces.…”

Section: Introductionmentioning

confidence: 99%

Capillary assembly of colloidal particles on patterned surfaces

et al. 2020

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Capillary attraction at the meniscus between tiny objects plays a crucial role in self-assembly processes. The shape of the meniscus governed by the Laplace equation devotes to a long-range attraction distinct to the DLVO defined forces. Rather than considering trapped particles on ideal smooth surfaces, we use patterned substrates with ordered nano-arrays for theoretical modeling toward the capillary assembly. The vertical elevation of particles is found to change the shape of the meniscus between particles, therefore the interaction energy and capillary force. A minimal model is developed to determine the capillary force between particles and thus the motility of particles, therefore the criterion of the crystallization of colloidal particles. It turns out that the formation of a colloidal crystal or amorphous medium depends on the optimization between the scaled particle separation by its size and the geometrical design of the supporting nano-arrays. Finally, we experimentally confirmed the capillary assembly from colloidal suspensions, by playing the control parameters defined in our theoretical model, with a nice agreement. This model system can mimic the practical applications of nano-structure fabrication on versatile real surfaces for functionality purposes.

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Identifying the nature of surface chemical modification for directed self-assembly of block copolymers

Cited by 7 publications

References 38 publications

Role of Penetrability into a Brush-Coated Surface in Directed Self-Assembly of Block Copolymers

Role of Penetrability into a Brush-Coated Surface in Directed Self-Assembly of Block Copolymers

Directed Self-Assembly of Block Copolymers for the Fabrication of Functional Devices

Capillary assembly of colloidal particles on patterned surfaces

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