Applications of molecular modeling in nanolithography

Pawloski, Adam R.; Torres, J. Andres; Nealey, Paul F.; Pablo, Juan J. de

doi:10.1116/1.591013

Cited by 14 publications

(16 citation statements)

References 16 publications

(9 reference statements)

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“…the different relative position of the hydroxyls, the ortho−para systems exhibited little intrachain bonding (<2%) as seen in Figure 3B. Rather, the 9OP systems showed a much stronger tendency toward interchain hydrogen bonding as observed in previous un-cross-linked studies by Pawloski et al 50 Figure 3B shows the percentage of interchain H-bonding to be ∼24% at D = 0% and ∼14% at D = 85%. This large fraction of interchain bonding produced a 3D network of hydrogen bonds which percolated the system.…”

Section: ■ Resultssupporting

confidence: 59%

See 1 more Smart Citation

Computational and Experimental Study of Phenolic Resins: Thermal–Mechanical Properties and the Role of Hydrogen Bonding

Monk¹,

Bucholz²,

Boghozian³

et al. 2015

Macromolecules

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Molecular dynamics simulations and experimental measurements were used to investigate the thermal and mechanical properties of cross-linked phenolic resins as a function of the degree of cross-linking, the chain motif (ortho−ortho versus ortho−para), and the chain length. The chain motif influenced the type (interchain or intrachain) as well as the amount of hydrogen bonding. Ortho− ortho chains favored internal hydrogen bonding whereas ortho−para favored hydrogen bonding between chains. Un-cross-linked ortho− para systems formed percolating 3D networks of hydrogen bonds, behaving effectively as "hydrogen gels". This resulted in differing thermal and mechanical properties for these systems. As crosslinking increased, the chain motif, chain length, and hydrogen bonding networks became less important. Elastic moduli, thermal conductivity, and glass transition temperatures were characterized as a function of cross-linking and temperature. Both our own experimental data and literature values were used to validate our simulation results. ■ INTRODUCTIONThermosetting resins, such as phenolic, polycyanurates, epoxies, and polyimides, have numerous applications as adhesives, coatings, and constituents for composite materials. The irreversible three-dimensional cross-linked networks formed during cure distinguish them from their thermoplastic analogues. Cross-linked structures result in stiffer mechanical properties even at elevated temperatures. Phenolic resins in particular are an important component of ablative thermal protection materials due to their high strength, low thermal conductivity, and high char yield. Ablative composites are stateof-the-art heat shield materials that protect space vehicles from extreme atmospheric entry conditions; examples of this class of materials include PICA 1−3 and Carbon Phenolic. 4,5 Experimental characterization of phenolic resins has spanned many decades due to their versatile applications in industry, 6,7 academics, 8−11 and government. 12−16 Numerous experimental results on isolated phenolic resins as well as in composites have been published to understand their characteristics and properties as a function of cure, 17−22 processing, 23−27 and composite design. 10,28−33 In addition, experimental properties such as the coefficients of thermal expansion, 12,20,34 thermal conductivity, 18,19,32 and elastic moduli 15,35,36 have been reported. Phenolic resins also have disadvantages, however, which include void formation and shrinkage that occur during processing as well as its brittle nature when highly cured. Recent experimental work has shown that thermomechanical properties can be improved substantially by introducing additives and varying processing conditions. 2,3 Understanding the relationship between chemical structures, properties, and processing will lead to improved, high-performance resins for this important class of materials.Advanced simulation studies are expected to play an important role in complementing and guiding experimental design for these systems. Recently, Li ...

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Section: ■ Resultssupporting

confidence: 59%

“…Pawloski et al also performed MD simulations of un-cross-linked phenolic to explain features observed in nanolithography. 50 Their work showed that ortho−para chains tend toward intermolecular …”

mentioning

confidence: 99%

Computational and Experimental Study of Phenolic Resins: Thermal–Mechanical Properties and the Role of Hydrogen Bonding

Monk¹,

Bucholz²,

Boghozian³

et al. 2015

Macromolecules

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“…Thermoset resins are well-suited for atomistic simulations which can establish the relationship between the chemical structure of the polymers and their material properties, such as mechanical [8][9][10][11] and thermal responses [12]. Recently, molecular dynamics (MD) simulations have been used to model other thermoset systems such as epoxies [13][14][15][16][17][18][19][20][21][22][23] as well as phenolic resins [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of phenolic resin: Construction of atomistic models

Monk

Haskins

Bauschlicher

et al. 2015

Polymer

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“…As features become progressively smaller, molecular scale effects become increasingly more important 4 . It is expected that interest in mesoscale models for optical and imprint lithography will grow as continuum models become obsolete.…”

Section: Mesoscale Modelingmentioning

confidence: 99%

Mesoscale modeling for SFIL simulating polymerization kinetics and densification

et al. 2004

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Step and Flash Imprint Lithography (SFIL) is a revolutionary next generation lithography option that has become increasingly attractive in recent years. Elimination of the costly optics of current step and scan imaging tools makes SFIL a serious candidate for large-scale commercial patterning of critical dimensions below ~50 nm. This work focuses on the kinetics of the UV curing of the liquid etch barrier and the resulting densification/contraction of the etch barrier as it solidifies during this step. Previous experimental work in our group has measured the bulk densification of several etch barrier formulations, typically about 9 % (v/v). It remains unknown, however, how much etch barrier contraction occurs during the formation of nano-scale features. Furthermore, it is of interest to examine how changes in monomer pendant group size impact imprinted feature profiles.This work provides answers to these questions through a combination of modeling and experimental efforts. Densification due to the photopolymerization reaction and the resulting shift from Van der Waals' to covalent interactions is modeled using Monte-Carlo techniques. The model allows for determination of extent of reaction, degree of polymerization, and local density changes as a function of the etch barrier formulation and the interaction energies between molecules (including the quartz template). Experimental efforts focus on a new technique to examine trench profiles in the quartz template using TEM characterization. Additionally, SEM images of imprinted images from various etch barrier formulations were examined to determine local contraction of the etch barrier. Over a large range of etch barrier formulations, which range from 10 -20 % volumetric contraction as bulk materials, it was found that dense 100 nm lines printed approximately the same size and shape.

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Applications of molecular modeling in nanolithography

Cited by 14 publications

References 16 publications

Computational and Experimental Study of Phenolic Resins: Thermal–Mechanical Properties and the Role of Hydrogen Bonding

Computational and Experimental Study of Phenolic Resins: Thermal–Mechanical Properties and the Role of Hydrogen Bonding

Molecular dynamics simulations of phenolic resin: Construction of atomistic models

Mesoscale modeling for SFIL simulating polymerization kinetics and densification

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