Morphology Control in Block Copolymer Films Using Mixed Solvent Vapors

Gotrik, Kevin W.; Hannon, Adam F.; Son, Jeong Gon; Keller, Brent D.; Alexander‐Katz, Alfredo; Ross, Caroline A.

doi:10.1021/nn302641z

Cited by 203 publications

(306 citation statements)

References 50 publications

Supporting

Mentioning

304

Contrasting

Order By: Relevance

“…The results of simulations are validated through comparison with detailed images from fully 3D, transmission-electron-microscopy (TEM) tomography in thin copolymer films. We conclude this introductory section by noting that although our focus is thermal annealing, a future study will consider the more specialized problem of how thermal pathways can be altered (or not) through controlled addition of solvents (11,15,16).…”

mentioning

confidence: 99%

Molecular pathways for defect annihilation in directed self-assembly

Hur

Thapar

Ramírez-Hernández

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

140

View full text Add to dashboard Cite

Over the last few years, the directed self-assembly of block copolymers by surface patterns has transitioned from academic curiosity to viable contender for commercial fabrication of nextgeneration nanocircuits by lithography. Recently, it has become apparent that kinetics, and not only thermodynamics, plays a key role for the ability of a polymeric material to self-assemble into a perfect, defect-free ordered state. Perfection, in this context, implies not more than one defect, with characteristic dimensions on the order of 5 nm, over a sample area as large as 100 cm 2 . In this work, we identify the key pathways and the corresponding free energy barriers for eliminating defects, and we demonstrate that an extraordinarily large thermodynamic driving force is not necessarily sufficient for their removal. By adopting a concerted computational and experimental approach, we explain the molecular origins of these barriers and how they depend on material characteristics, and we propose strategies designed to overcome them. The validity of our conclusions for industrially relevant patterning processes is established by relying on instruments and assembly lines that are only available at state-of-the-art fabrication facilities, and, through this confluence of fundamental and applied research, we are able to discern the evolution of morphology at the smallest relevant length scales-a handful of nanometers-and present a view of defect annihilation in directed self-assembly at an unprecedented level of detail.directed self-assembly | copolymer | defect | minimum free energy path | string method O ver the last decade, the directed self-assembly (DSA) of block copolymers has rapidly evolved from mere intellectual curiosity (1-4) to a potentially crucial step in the commercial fabrication of next-generation electronic circuits. Indeed, the characteristic length scale of ordered self-assembled copolymer domains is in the range of 5-50 nm. Furthermore, their size and shape can be manipulated through simple processing steps, thereby making them attractive for the production of semiconductor devices, nanofluidic devices, or high-density storage media (5, 6). The general idea behind copolymer DSA is that a surface patternchemical or topographic-can be used to guide the assembly of a polymeric material into an ordered, device-like structure that is free of defects. In so-called "density multiplication" patterning strategies (7,8), the spacing or pitch of the surface features can be much larger than the characteristic dimensions of the copolymer of interest. One can thus prepare coarse surface patterns, which are easier to create, and rely on the copolymer to self-assemble into features whose density is considerably larger. Fig. 1 shows a schematic representation of the process for obtaining a lamellar morphology on a stripe-patterned substrate under a one-to-three (or 3X) density multiplication strategy. Patterned stripes interact preferentially with one of the blocks and guide the assembly of thin copolymer films into ordered lam...

show abstract

mentioning

confidence: 99%

Molecular pathways for defect annihilation in directed self-assembly

Hur

Thapar

Ramírez-Hernández

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

140

View full text Add to dashboard Cite

show abstract

“…The films were solvent annealed using either a flow-controlled solvent annealing system or conventional solvent annealing system for 3 h. In the flow-controlled solvent annealing system, nitrogen gas was bubbled through a liquid reservoir of a 5:1 mixture of toluene and heptane at a flow rate of 10 sccm and diluted by nitrogen gas flow of 0.7 sccm so that the annealing chamber was maintained at constant solvent vapour pressure. The vapour pressure was controlled by changing the flow ratio between the solvent stream and the nitrogen stream 42 . In the conventional solvent annealing system, the sample was placed in a chamber containing a reservoir of liquid solvent (5:1 mixture of toluene and heptane).…”

Section: Methodsmentioning

confidence: 99%

Design rules for self-assembled block copolymer patterns using tiled templates

et al. 2014

Self Cite

View full text Add to dashboard Cite

Directed self-assembly of block copolymers has been used for fabricating various nanoscale patterns, ranging from periodic lines to simple bends. However, assemblies of dense bends, junctions and line segments in a single pattern have not been achieved by using sparse templates, because no systematic template design methods for achieving such complex patterns existed. To direct a complex pattern by using a sparse template, the template needs to encode the key information contained in the final pattern, without being a simple copy of the pattern. Here we develop a set of topographic template tiles consisting of square lattices of posts with a restricted range of geometric features. The block copolymer patterns resulting from all tile arrangements are determined. By combining tiles in different ways, it is possible to predict a relatively simple template that will direct the formation of non-trivial block copolymer patterns, providing a new template design method for a complex block copolymer pattern.

show abstract

“…27,28 One gas stream was dry air, whereas the other stream was nearly saturated solvent vapor, generated by bubbling dry air through the liquid solvent. Four different solvents were utilized for SVA: toluene, THF, 1,4-dioxane, and DMF.…”

Section: Acs Applied Materials and Interfacesmentioning

confidence: 99%

“…26,27 The variation in solvent properties by use of mixtures provides a facile route to tuning the morphology of BCP films using SVA. 27,28 These processing steps are necessary in most cases, as the non-neutral wetting conditions for most BCP films with anisotropic morphologies tend to favor the parallel orientation.…”

Section: ■ Introductionmentioning

confidence: 99%

Impact of Nanostructure on Mechanical Properties of Norbornene-based Block Copolymers under Simulated Operating Conditions for Biobutanol Membranes

Takigawa

Burtovvy

et al. 2015

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

The structure and mechanical properties of a novel block copolymer (BCP) system with T(g)'s for both segments exceeding 300 °C, poly(butylnorbornene)-block-poly(hydroxyhexafluoroisopropyl norbornene) (BuNB-b-HFANB), are investigated as a function of processing conditions used for solvent vapor annealing (SVA). Solvent selection impacts long-range order markedly, but unexpectedly vertical orientation of cylinders are preferred over a wide range of solubility parameters, as determined by atomic force microscopy and grazing incidence small-angle X-ray scattering. The mechanical properties (elastic modulus, fracture strength, and onset fracture strain) are dependent upon the long-range order induced during SVA and determined using the combination of surface wrinkling and cracking. The modulus and fracture strength of the films increase from 1.44 GPa and 12.1 MPa to 1.77 GPa and 17.5 MPa, respectively, whereas the onset fracture strain decreases from 1.6% to approximately 0.6% as the ordering is improved. The polarity difference in the segments of the BCP is attractive for membrane separations, especially butanol-water. For biobutanol recovery, the titers are typically <3 wt % butanol; exposure of the BCP membrane to aqueous 1 wt % butanol decreases the elastic modulus to approximately 0.90 GPa, irrespective of the morphology, despite the high T(g) of both segments and limited swelling (5.0 wt %). Correspondingly, the onset fracture strain of these swollen films is estimated to increase significantly to 6-7%. These results indicate that operating conditions impact the mechanical performance of BCP membranes more than their morphology despite the high T(g) of the neat copolymer. Wrinkling and cracking provide a facile route to test the mechanical properties of membranes under simulated operando conditions.

show abstract

Morphology Control in Block Copolymer Films Using Mixed Solvent Vapors

Cited by 203 publications

References 50 publications

Molecular pathways for defect annihilation in directed self-assembly

Molecular pathways for defect annihilation in directed self-assembly

Design rules for self-assembled block copolymer patterns using tiled templates

Impact of Nanostructure on Mechanical Properties of Norbornene-based Block Copolymers under Simulated Operating Conditions for Biobutanol Membranes

Contact Info

Product

Resources

About