Limits of Directed Self-Assembly in Block Copolymers

Gadelrab, Karim; Ding, Yi; Pablo-Pedro, Ricardo; Chen, Hsieh; Gotrik, Kevin W.; Tempel, David G.; Ross, Caroline A.; Alexander‐Katz, Alfredo

doi:10.1021/acs.nanolett.8b00997

Cited by 15 publications

(18 citation statements)

References 41 publications

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“…It has pushed the limits of feature size, offering extremely low defectivity and high throughput on large areas with sub-lithographic resolution (≈ 10 nm). BCP has great potential for nanoelectronics devices, energy conversion, and storage [42][43][44]. Table 1.…”

Section: Pros and Cons Of The Nanosphere Lithography For Diamond Strumentioning

confidence: 99%

Nanosphere Lithography for Structuring Polycrystalline Diamond Films

2020

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This paper deals with the structuring of polycrystalline diamond thin films using the technique of nanosphere lithography. The presented multistep approaches relied on a spin-coated self-assembled monolayer of polystyrene spheres, which served as a lithographic mask for the further custom nanofabrication steps. Various arrays of diamond nanostructures-close-packed and non-close-packed monolayers over substrates with various levels of surface roughness, noble metal films over nanosphere arrays, ordered arrays of holes, and unordered pores-were created using reactive ion etching, chemical vapour deposition, metallization, and/or lift-off processes. The size and shape of the lithographic mask was altered using oxygen plasma etching. The periodicity of the final structure was defined by the initial diameter of the spheres. The surface morphology of the samples was characterized using scanning electron microscopy. The advantages and limitations of the fabrication technique are discussed. Finally, the potential applications (e.g., photonics, plasmonics) of the obtained nanostructures are reviewed.

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Section: Pros and Cons Of The Nanosphere Lithography For Diamond Strumentioning

confidence: 99%

Nanosphere Lithography for Structuring Polycrystalline Diamond Films

2020

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“…Mesoscopic modeling is a flexible and powerful theoretical tool to study inhomogeneous polymeric systems. Among the various modeling methods, MesoDyn has been validated as an effective approach to explore the phase behavior of polymer systems at the mesoscale [43,44,45,46,47,48]. Furthermore, MesoDyn facilitates treating various chain architectures of polymers, from linear [49] to branched [41,42,50]; MesoDyn is a mature method to investigate the phase behavior of flexible block copolymers.…”

Section: Models and Parameter Settingsmentioning

confidence: 99%

Mesoscopic Detection of the Influence of a Third Component on the Self-Assembly Structure of A2B Star Copolymer in Thin Films

Cong

et al. 2019

Polymers

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The most common self-assembly structure for A2B copolymer is the micellar structure with B/A segments being the core/corona, which greatly limits its application range. Following the principle of structure deciding the properties, a reformation in the molecular structure of A2B copolymer is made by appending three segments of a third component C with the same length to the three arms, resulting (AC)2CB 3-miktoarm star terpolymer. A reverse micellar structure in self-assembly is expected by regulating the C length and the pairwise repulsive strength of C to A/B, aiming to enrich its application range. Keeping both A and B lengths unchanged, when the repulsion strength of C to A is much stronger than C to B, from the results of mesoscopic simulations we found, with a progressive increase in C length, (AC)2CB terpolymer undergoes a transition in self-assembled structures, from a cylindrical structure with B component as the core, then to a deformed lamellar structure, and finally to a cylindrical structure with A component as the core. This reverse micellar structure is formed with the assistance of appended C segments, whose length is longer than half of B length, enhancing the flexibility of three arms, and further facilitating the aggregation of A component into the core. These results prove that the addition of a third component is a rational molecular design, in conjunction with some relevant parameters, enables the manufacturing of the desired self-assembly structure while avoiding excessive changes in the involved factors.

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“…The design of such patterned substrates can be facilitated by using computer simulations . To model structures on given substrate patterns, simulations were already employed in some of the examples discussed above, e.g., Ruiz et al or Tavakkoli et al Computers have also been useful in identifying the limits of directing self‐assembly on substrate patterns with random imperfections, and have been successfully used for predicting the substrate patterns required for directing block copolymer self‐assembly into desired morphologies . Such indirect modeling efforts for directed self‐assembly can be expected to become a powerful tool for the patterning of more complex self‐assembled structures in 3D.…”

Section: Directing Block Copolymer Self‐assembly In Three Dimensionsmentioning

confidence: 99%

Directing Block Copolymer Self‐Assembly on Patterned Substrates

Gunkel

2018

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of block copolymer self-assembly and its low thermodynamic driving force leads to the simultaneous formation of multiple uncorrelated grains with trapped defects at their boundaries, which significantly limits usability. Furthermore, in films, one of the blocks often preferentially wets the substrate surface, which may cause the formation of patterns that cannot be used for applications. These fundamental challenges to generating desired block copolymer patterns have motivated researchers to find ways to control orientation and ordering in films, resulting in various successful means to induce block copolymer alignment and defect elimination. [15,16] Alignment and ordering strategies include the application of external electric [17] or magnetic fields, [18] solvent vapor annealing, [19,20] and the use of patterned substrates. [21][22][23] The use of either chemically [24] or topographically [25][26][27][28] patterned substrates to direct block copolymer selfassembly in films is particularly interesting as it allows the control of domain orientation, the creation of defect-free patterns, and precise pattern registration on a substrate (Figure 2), which is especially interesting for applications requiring addressability of nanoscale features. The use of substrates with particular chemical patterns allows directing block copolymers to perfectly replicate the underlying pattern [24] (Figure 2c) and has therefore been termed epitaxial self-assembly or "chemoepitaxy." Guiding the assembly of block copolymers by topographical features of lithographically defined substrate patterns is also known as "graphoepitaxy" [25] -it refers to the use of a topographic substrate to, for example, preferentially align block copolymer lamellae parallel to the trenches (Figure 2d). These hybrid approaches combine bottom-up self-assembly with topdown patterning to precisely define desired substrate patterns. This concept focuses on directing the self-assembly of block copolymers using chemically and topographically patterned substrates. The reader is referred to recent reviews for details on the fabrication of chemical [22,29,30] and topographic patterns, [31] as well as alternative approaches to controlling block copolymer self-assembly, e.g., by using interfacial effects, solvents, film deposition processes, and advanced thermal annealing. [15,16,21,32] Chemical Patterning: ChemoepitaxyThe chemical patterning of block copolymers has been closely linked to one specific diblock copolymer, namely, polystyreneb-poly(methyl methacrylate) (PS-b-PMMA). The chemical Self-assembling block copolymer films provide access to a variety of different nanostructured patterns in one, two, and three dimensions. However, in the absence of any templating, these nanostructures suffer from defects, often limiting utility. Directed block copolymer self-assembly uses patterned substrates that effectively suppress defect formation and allow the creation of desired patterns. The two main directed self-assembly techniques, chemoepitaxy and graphoepitaxy, employ...

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Limits of Directed Self-Assembly in Block Copolymers

Cited by 15 publications

References 41 publications

Nanosphere Lithography for Structuring Polycrystalline Diamond Films

Nanosphere Lithography for Structuring Polycrystalline Diamond Films

Mesoscopic Detection of the Influence of a Third Component on the Self-Assembly Structure of A2B Star Copolymer in Thin Films

Directing Block Copolymer Self‐Assembly on Patterned Substrates

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