Influence of elastic strains on the mask ratio in glassy polymer nanoimprint

Cross, Graham L. W.; O’Connell, Barry; Pethica, J. B.

doi:10.1063/1.1868074

Cited by 30 publications

(34 citation statements)

References 14 publications

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“…11,12 Arbitrary embossing values such as T emb =(T g + n) uC (where n is a universal integer) are most unlikely to provide optimal embossing conditions. Careful optimization of the process parameters, especially the embossing temperature (T emb ), is required to avoid damaging the embossing stack, as well as to avoid trapping residual stress and subsequent rebound, 13 and also to avoid unduly long cycle times caused by excessive heating and cooling. Choosing by how much the embossing temperature should exceed the T g is a compromise between the reduction in the polymer moduli that facilitate faithful motif replication and the potential damage to stamp and substrate caused by longer cycle times and greater thermal distortion.…”

Section: Hel and The Glass Transitionmentioning

confidence: 99%

High fidelity, high yield production of microfluidic devices by hot embossing lithography: rheology and stiction

et al. 2006

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Section: Hel and The Glass Transitionmentioning

confidence: 99%

High fidelity, high yield production of microfluidic devices by hot embossing lithography: rheology and stiction

et al. 2006

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“…Through a number of studies performed to identify polymer deformation behavior [8][9][10][11][12][13], it has been revealed that the quality of pattern transfer can be significantly degraded because of several undesirable phenomena, such as lack of stamp cavity filling [8][9][10][11], limitation of residual layer thickness due to the unextruded polymer film [12], and recovery of the compressed polymer film [13]. These kinds of defects become significant and inevitable as a pattern aspect ratio grows higher and the thickness of the residual film becomes lower.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics study of pattern transfer in nanoimprint lithography

Kang

Kim

2007

Tribol Lett

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A molecular dynamics simulations model of nanoimprint lithography (NIL) is proposed in order to study the pattern transfer and its related phenomena. The proposed model is similar to a real NIL process imprinting an a-quartz stamp with a rectangular line pattern into an amorphous poly-(methylmethacrylate) (PMMA) film. The polymer deformation behavior and the adhesion and friction effects between the stamp and the polymer film are investigated and their dependency on the pattern aspect ratio is discussed. Force fields including bond, angle, torsion, van der Waals, and electrostatic potentials are used to describe intermolecular and intramolecular interacting forces. Nose´-Hoover thermostat is used to control the temperature of the polymer film and cell multipole method is adopted to treat long range interactions. The deformation of the polymer film is observed for two stamps having different aspect ratio patterns. The distributions of density and stress in the polymer film are calculated for the detail analysis of deformation behavior. For a high aspect ratio pattern (aspect ratio = 2.5, imprint depth = 8.0 nm), large amount of springback of the residual polymer film is observed, which is mainly due to the residual compressive stress left in the polymer film. However, for a low aspect ratio pattern (aspect ratio = 1.0, imprint depth = 3.0 nm), the springback is not observed. In addition, adhesion and friction forces are obtained by dividing the polymer film into subregions and calculating the interacting force between each subregion and the stamp. While the adhesion force is nearly constant regardless of the pattern aspect ratio, the friction force increases as the pattern aspect ratio grows, so the friction force becomes larger than the adhesion force when the pattern aspect ratio increases.

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“…[16,17] Although low temperature patterning of glassy polymers has been demonstrated, most thermal-embossing NIL is performed at temperatures above the glass-transition temperature (T g ) of the polymer. [18] The patterning resolution is determined by the viscoelastic deformation of thin polymer films under applied pressure. It is well known that the molar mass affects many of the physical properties of a polymer, especially rheological ones.…”

Section: Introductionmentioning

confidence: 99%

Nanoimprint Lithography and the Role of Viscoelasticity in the Generation of Residual Stress in Model Polystyrene Patterns

Ding

Alvine

et al. 2008

Adv Funct Materials

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Understanding polymer deformation during the nanoimprinting process is key to achieving robust polymer nanostructures. Information regarding this process can be extracted from monitoring the decay of the imprinted polymer patterns during thermal annealing. In the present work, the effect of both the molar mass and the imprinting temperature on the pattern decay behavior during thermal annealing is investigated. Previously, it was found that the decay rate is fastest for a highly entangled polymer due to the elastic recovery caused by the residual stress created during the imprinting process. The present paper demonstrates that this residual stress level can be modified through control of the imprinting temperature. These results are contrasted with those for an unentangled polymer over a similar range of imprinting temperatures, where it is found that the pattern decay is controlled by simple Newtonian flow. In particular, the pattern decay is well described by surface‐tension‐driven viscous flow, and no imprinting‐temperature effect is observed during thermal annealing. It is shown that the stability of the film against pattern decay can be optimized for moderately entangled polymer films. This effect is attributed to the competition between the effect of increased viscosity with increasing molar mass and increased residual stresses with entanglements. These observations provide guidance for the optimization of imprinting process in terms of selection of molar mass and processing temperatures.

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Influence of elastic strains on the mask ratio in glassy polymer nanoimprint

Cited by 30 publications

References 14 publications

High fidelity, high yield production of microfluidic devices by hot embossing lithography: rheology and stiction

High fidelity, high yield production of microfluidic devices by hot embossing lithography: rheology and stiction

Molecular dynamics study of pattern transfer in nanoimprint lithography

Nanoimprint Lithography and the Role of Viscoelasticity in the Generation of Residual Stress in Model Polystyrene Patterns

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