Three‐Dimensional Nanofabrication by Block Copolymer Self‐Assembly

Ross, Caroline A.; Berggren, Karl K.; Cheng, Joy Y.; Jung, Yeon Sik; Chang, Jae-Byum

doi:10.1002/adma.201400386

Cited by 160 publications

(144 citation statements)

References 190 publications

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“…16 To obtain microphase separation at sub-10nm length scales, a high Flory-Huggins interaction parameter (χ) is desirable. However, high-χ BCPs usually exhibit large differences in surface affinity between the two blocks, leading to the formation of a surface layer of the lower surface energy block and favoring in-plane orientation of lamellae or cylindrical microdomains, 17 which is exacerbated if the substrate is also preferential to one block.…”

Section: Toc Graphic Article Textmentioning

confidence: 99%

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Perpendicular Block Copolymer Microdomains in High Aspect Ratio Templates

et al. 2015

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Perpendicular orientation of lamellar microdomains in a high interaction parameter block copolymer was obtained within high aspect ratio gratings functionalized with a preferential sidewall brush. The experiments used polystyrene-blockpolydimethylsiloxane with molecular weight 43 kg/mol within trenches made using interference lithography. The perpendicular alignment was obtained for both thermal and solvent annealing, using three different solvent vapors, for a range of film thicknesses and trench widths. A Pt layer at the base of the trenches avoided the formation of a wetting layer, giving perpendicular orientation at the substrate surface. The results are interpreted using self-consistent field theory simulation and a Ginzburg-Landau analytic model to map the energies of lamellae of different orientations as a function of the grating aspect ratio and the surface energies of the sidewalls and top and bottom surfaces. The model results agree with the experiment and provide a set of guidelines for obtaining perpendicular microdomains within topographic features. Keywords: Block Copolymer, self-assembly, perpendicular orientation, graphoepitaxy, solvent annealing, thermal annealing TOC Graphic Article TextBlock copolymer (BCP) films have shown great utility in several technological applications including nanolithography for fabrication of integrated circuits, 1,2 magnetic storage media, 3,4 or sensors; 5-7 and in photonic crystals, [8][9][10] photovoltaics [11][12][13] and separation membranes, 14,15 as well as for making 3-dimensional nanostructures. 16 To obtain microphase separation at sub-10nm length scales, a high Flory-Huggins interaction parameter (χ) is desirable. However, high-χ BCPs usually exhibit large differences in surface affinity between the two blocks, leading to the formation of a surface layer of the lower surface energy block and favoring in-plane orientation of lamellae or cylindrical microdomains, 17 which is exacerbated if the substrate is also preferential to one block. This is undesirable in applications where through-thickness features are required, such as porous membranes or high-aspect-ratio structures for pattern transfer. Perpendicular (vertical) orientation of block copolymer microdomains can be produced by several methods, including i) a neutral top coating and neutral substrate brush that minimize the interfacial energy difference between the blocks at the air and substrate interfaces respectively; [17][18][19] ii) a specifically designed molecular architecture 20-22 such as a brush or multi-arm BCP that can form microdomains oriented out-of-plane without modification of the underlying substrate, due to the entropic penalty associated with the packing of the side chains; 22 and iii) modifying the annealing process to use a solvent concentration gradient, 18,23 temperature gradient, 24,25 electric 26 or magnetic field 27 , chemoepitaxy and/or graphoepitaxy, 28 and electrospray deposition 29 to induce out-ofplane alignment of self-assembled microdomains. These methods have ...

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Section: Toc Graphic Article Textmentioning

confidence: 99%

“…16,38 In a high aspect-ratio template we consider three pairs of interfacial energies with respect to a lamellar-forming A-B diblock copolymer: γ Top , γ Bot , γ Side , where γ is the interfacial energy and "Top", "Bot", and "Side" refer to the top (i.e. air surface), bottom and sidewall surface, respectively, as shown in figure 1a.…”

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Perpendicular Block Copolymer Microdomains in High Aspect Ratio Templates

et al. 2015

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“…We comment on triblock copolymer materials in the penultimate section of this review to provide further insights into potential future directions. In a recent research news article, Ross et al [ 47 ] emphasized the potential of utilizing 3D BCP patterns for batteries, membranes or photovoltaic application as placement of features and defect levels are not as stringent as for integrated circuit application. With this in mind, the ability to replicate 3D BCP patterns using inorganic strategies described in this review may allow low-cost high density fabrication practices for nanomanufacturing.…”

Section: Reviewmentioning

confidence: 99%

Strategies for Inorganic Incorporation using Neat Block Copolymer Thin Films for Etch Mask Function and Nanotechnological Application

et al. 2016

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Block copolymers (BCPs) and their directed self-assembly (DSA) has emerged as a realizable complementary tool to aid optical patterning of device elements for future integrated circuit advancements. Methods to enhance BCP etch contrast for DSA application and further potential applications of inorganic nanomaterial features (e.g., semiconductor, dielectric, metal and metal oxide) are examined. Strategies to modify, infiltrate and controllably deposit inorganic materials by utilizing neat self-assembled BCP thin films open a rich design space to fabricate functional features in the nanoscale regime. An understanding and overview on innovative ways for the selective inclusion/infiltration or deposition of inorganic moieties in microphase separated BCP nanopatterns is provided. Early initial inclusion methods in the field and exciting contemporary reports to further augment etch contrast in BCPs for pattern transfer application are described. Specifically, the use of evaporation and sputtering methods, atomic layer deposition, sequential infiltration synthesis, metal-salt inclusion and aqueous metal reduction methodologies forming isolated nanofeatures are highlighted in di-BCP systems. Functionalities and newly reported uses for electronic and non-electronic technologies based on the inherent properties of incorporated inorganic nanostructures using di-BCP templates are highlighted. We outline the potential for extension of incorporation methods to triblock copolymer features for more diverse applications. Challenges and emerging areas of interest for inorganic infiltration of BCPs are also discussed.

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“…These applications require the use of BCPs in thin film geometries (< 100 nm thickness), where self-assembly is strongly influenced by different parameters. The simplicity and cost-effectiveness of the spontaneous BCP self-assembly process is attractive and holds promise for applications in nanolithography [9][10][11][12], with demonstrated capabilities in the fabrication of nanoscale devices [1]. Specifically, the use of cylindrical phase BCPs has been demonstrated for printing the capacitor layer of dynamic access memory devices [13][14][15].…”

Section: Introductionmentioning

confidence: 98%