Perpendicular orientation of cylindrical domains upon solvent annealing thin films of polystyrene-b-polylactide

Vayer, Marylène; Hillmyer, Marc A.; Dirany, Mohammed; Thevenin, G.; Erre, R.; Sinturel, Christophe

doi:10.1016/j.tsf.2009.10.015

Cited by 76 publications

(117 citation statements)

References 36 publications

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“…[34][35][36][37][38] These morphological changes can then be kinetically trapped by flash removal of the solvent from the system. However, a disadvantage of this approach is that this additional step requires additional infrastructure in the fab (semiconductor fabrication facility) and strict control over the experimental parameters to achieve reproducible results.…”

Section: Introductionmentioning

confidence: 99%

Can ionic liquid additives be used to extend the scope of poly(styrene)-block-poly(methyl methacrylate) for directed self-assembly?

Bennett

Pei

Cheng

et al. 2014

J. Micro/Nanolith. MEMS MOEMS

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Abstract. Directed self-assembly (DSA) is a promising approach for extending conventional lithographic techniques by being able to print features with critical dimensions under 10 nm. The most widely studied block copolymer system is polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA). This system is well understood in terms of its synthesis, properties, and performance in DSA. However, PS-b-PMMA also has a number of limitations that impact on its performance and hence scope of application. The primary limitation is the low Flory-Huggins polymer-polymer interaction parameter (χ), which limits the size of features that can be printed. Another issue with block copolymers in general is that specific molecular weights need to be synthesized to achieve desired morphologies and feature sizes. Here we explore blending ionic liquid (IL) additives with PS-b-PMMA to increase the χ parameter. ILs have a number of useful properties that include negligible vapor pressure, tunable solvent strength, thermal stability, and chemical stability. The blends of PS-b-PMMA with an IL selective for the PMMA block allowed the resolution of the block copolymer to be improved. Depending on the amount of additive, it is also possible to tune the domain size and the morphology of the systems. These findings may expand the scope of PS-b-PMMA for DSA.

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Section: Introductionmentioning

confidence: 99%

Can ionic liquid additives be used to extend the scope of poly(styrene)-block-poly(methyl methacrylate) for directed self-assembly?

Bennett

Pei

Cheng

et al. 2014

J. Micro/Nanolith. MEMS MOEMS

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show abstract

“…The affinity of one block with the solvent, for example PLA with acetone will encourage migration of PLA to the surface to shield the PS chains from unfavorable contact with a non-solvent. 11 THF on the other hand is a polar solvent and selective for both PS and PLA. As there is no strong preference of the blocks to the solvent, the polymer/air surface will be neutral for both components.…”

Section: And Discussionmentioning

confidence: 99%

“…PLA is a biodegradable aliphatic polyester and can be chemically etched to provide an on-chip etch mask for pattern transfer. 11,12,13 In hexagonal forming PS-b-PLA the thermal annealing process can be very long (12 hours) and problematic due to thermal degradation of PLA. 12,14 Solvent annealing has been recently shown for PS-b-PLA seems more practical.…”

Section: Introductionmentioning

confidence: 99%

“…12,14 Solvent annealing has been recently shown for PS-b-PLA seems more practical. 11,15 Recent reports have examined lamellar forming PS-b-PLA systems. 16,17,18 Depending on the difference in the surface energy of the substrate/air with each block or the confinement effect, the lamellae can align either perpendicular or parallel to the substrate.…”

Section: Introductionmentioning

confidence: 99%

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Study of the Kinetics and Mechanism of Rapid Self-Assembly in Block Copolymer Thin Films during Solvo-Microwave Annealing

et al. 2014

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Microwave annealing is an emerging technique for achieving ordered patterns of block copolymer films on substrates. Little is understood about the mechanisms of microphase separation during the microwave annealing process and how it promotes the microphase separation of the blocks. Here, we use controlled power microwave irradiation in the presence of tetrahydrofuran (THF) solvent, to achieve lateral microphase separation in high-χ lamellar-forming poly(styrene-b-lactic acid) PS-b-PLA. A highly ordered line pattern was formed within seconds on silicon, germanium and silicon on insulator (SOI) substrates. In-situ temperature measurement of the silicon substrate coupled to condition changes during “solvo-microwave” annealing allowed understanding of the processes to be attained. Our results suggest that the substrate has little effect on the ordering process and is essentially microwave transparent but rather, it is direct heating of the polar THF molecules that causes microphase separation. It is postulated that the rapid interaction of THF with microwaves and the resultant temperature increase to 55 °C within seconds causes an increase of the vapor pressure of the solvent from 19.8 to 70 kPa. This enriched vapor environment increases the plasticity of both PS and PLA chains and leads to the fast self-assembly kinetics. Comparing the patterns formed on silicon, germanium and silicon on insulator (SOI) and also an in situ temperature measurement of silicon in the oven confirms the significance of the solvent over the role of substrate heating during “solvo-microwave” annealing. Besides the short annealing time which has technological importance, the coherence length is on a micron scale and dewetting is not observed after annealing. The etched pattern (PLA was removed by an Ar/O2 reactive ion etch) was transferred to the underlying silicon substrate fabricating sub-20 nm silicon nanowires over large areas demonstrating that the morphology is consistent both across and through the film.

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“…Block-copolymers (BCPs) have proved to be one of the most interesting soft materials to carry on scaling structures on surfaces down to the sub-10 nanometer nanoimprinting can guide the self-assembly of the BCP in alignment, orientation and control the feature size by graphoepitaxy and annealing procedures. [10,11] This soft lithography technique employed to align BCPs was first reported by Li et al on polystyrene-block-polymethyl metacrylate (PS-b-PMMA). [12] Many studies have been devoted to PS-b-PMMA since it is compatible with the established industry [10,13] In suitable self-assembly conditions, among them directed self-assembly (DSA), lamellar or cylindrical structures could be obtained on surface with pitches varying from 35 to 50 nm.…”

mentioning

confidence: 99%

Soft Graphoepitaxy of Hexagonal PS-b-PDMS on Nanopatterned POSS Surfaces fabricated by Nanoimprint Lithography

Simão

Francone

Borah

et al. 2012

J. Photopol. Sci. Technol.

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Directed self-assembly of block copolymer polystyrene-block-polydimethylsiloxane by combining graphoepitaxy using nanoimprinted polyhedral oligomeric silsesquioxanes thin films as substrates and solvent annealing resulted in the BCP microphase segregation. For this purpose, the substrates for graphoepitaxy were fabricated by patterning the soft material POSS as thin films on silicon with nanoimprint lithography. The directed self-assembly of PS-b-PDMS resulted in the microphase segregation of PDMS cylinders with 25 nm pore diameter imbedded in a PS matrix. By modulating the hydrophobicity of POSS substrates, it was possible to control the orientation of the PDMS cylinders. For more hydrophobic POSS surfaces, the cylinders oriented parallel to the side walls surfaces whereas in more hydrophilic POSS surfaces the cylinders were oriented perpendicular to the side walls.

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Perpendicular orientation of cylindrical domains upon solvent annealing thin films of polystyrene-b-polylactide

Cited by 76 publications

References 36 publications

Can ionic liquid additives be used to extend the scope of poly(styrene)-block-poly(methyl methacrylate) for directed self-assembly?

Can ionic liquid additives be used to extend the scope of poly(styrene)-block-poly(methyl methacrylate) for directed self-assembly?

Study of the Kinetics and Mechanism of Rapid Self-Assembly in Block Copolymer Thin Films during Solvo-Microwave Annealing

Soft Graphoepitaxy of Hexagonal PS-b-PDMS on Nanopatterned POSS Surfaces fabricated by Nanoimprint Lithography

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