Confinement and flow dynamics in thin polymer films for nanoimprint lithography

Teisseire, Jérémie; Revaux, Amélie; Foresti, M.; Barthel, Étienne

doi:10.1063/1.3535614

Cited by 31 publications

(52 citation statements)

References 29 publications

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“…Obviously, figure 3 indicates that the geometry of choice is thick layers, as slip conditions have no influence in such cases, and a good compromise is choosing a layer thickness that is equal to the profile wavelength. The viscosity is obtained from η = πγ τ/w, and one may wish to analyse the effect of very thin layers on viscosity, expecting a possible confinement effect such as in Teisseire et al [19], for instance, by considering very small wavelengths w (and, accordingly, small thicknesses h), keeping in mind that the present analysis neglects Van der Waals interactions that may be significant for very thin films. This will be limited first by relaxation times being shorter for smaller wavelengths, and therefore being more difficult to measure precisely.…”

Section: (D) Discussionmentioning

confidence: 99%

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On using the levelling of the free surface of a Newtonian fluid to measure viscosity and Navier slip length

Pierre

Teyssèdre

2013

Proc. R. Soc. A.

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Measuring the relaxation time involved in the levelling of a free surface of a Newtonian fluid laid on a substrate can give access to material parameters. It is shown here how most favourable pattern geometries of the free surface and film thicknesses can be defined for the measures of viscosity and Navier slip length at the fluid-solid interface, respectively. Moreover, we put special emphasis on the conditions required to avoid shear thinning by controlling the maximum shear rate. For initially sinusoidal patterns with infinitesimal amplitudes, an analytical solution including slip at the fluid-solid interface is used, and numerical simulations based on the natural element method allow one to discuss the effect of finite amplitudes. This leads to the definition of a relevance domain for the analytical solution that avoids the need for numerical simulations in practical applications. It is also shown how these results can be applied to crenelated profiles, where Fourier series expansion can be used, but with caution.

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Section: (D) Discussionmentioning

confidence: 99%

“…In the third and last case, an extremum is obtained at a depth 19) for any x value, where the generalized shear rate is such thaṫ…”

Section: (B) Profile Evolutionmentioning

confidence: 99%

On using the levelling of the free surface of a Newtonian fluid to measure viscosity and Navier slip length

Pierre

Teyssèdre

2013

Proc. R. Soc. A.

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“…However, it is also known that the mobility of polymers can be altered in thin films [1][2][3][4][5]. Thus, understanding the dynamics of thin films in their liquid state is essential to gaining control of pattern formation and relaxation on the nanoscale [6,7]. For example, high-density data storage in thin polymer films is possible by locally modifying a surface with a large 2-D array of atomic force microscope probes [8].…”

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confidence: 99%

Relaxation and intermediate asymptotics of a rectangular trench in a viscous film

Bäumchen¹,

Benzaquen²,

Salez³

et al. 2013

Phys. Rev. E

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The surface of a thin liquid film with nonconstant curvature flattens as a result of capillary forces. While this leveling is driven by local curvature gradients, the global boundary conditions greatly influence the dynamics. Here, we study the evolution of rectangular trenches in a polystyrene nanofilm. Initially, when the two sides of a trench are well separated, the asymmetric boundary condition given by the step height controls the dynamics. In this case, the evolution results from the leveling of two noninteracting steps. As the steps broaden further and start to interact, the global symmetric boundary condition alters the leveling dynamics. We report on full agreement between theory and experiments for: the capillary-driven flow and resulting time dependent height profiles; a crossover in the power-law dependence of the viscous energy dissipation as a function of time as the trench evolution transitions from two noninteracting to interacting steps; and the convergence of the profiles to a universal self-similar attractor that is given by the Green's function of the linear operator describing the dimensionless linearized thin film equation.PACS numbers: 47.15.gm, 47.55.nb, 47.85.mf, 83.80.Sg Thin films are prevalent in applications such as lubricants, coatings for optical and electronic devices, and nanolithography to name just a few. However, it is also known that the mobility of polymers can be altered in thin films [1][2][3][4][5]. Thus, understanding the dynamics of thin films in their liquid state is essential to gaining control of pattern formation and relaxation on the nanoscale [6,7]. For example, high-density data storage in thin polymer films is possible by locally modifying a surface with a large 2-D array of atomic force microscope probes [8]. This application relies on control of the time scales of the flow created by a surface profile to produce or erase a given surface pattern. In contrast to this technologically spectacular example is the surface of freshly applied paint which relies on the dynamics of leveling to provide a lustrous surface.Much has been learned about the physics of thin films from dewetting, where an initially flat film exposes the substrate surface to reduce the free energy of the system [9][10][11][12][13][14][15][16][17][18]. Other approaches, for example studying the evolution of surface profiles originating from capillary waves [19], embedding of nanoparticles [5], or those created by an external electric field [20,21] have also been utilized to explore mobility in thin films. Although the capillary-driven leveling of a nonflat surface topography in a thin liquid film has been reported in various studies [22,23], experiments with high resolution compared to a general theory that relates time scales to spatial geometries and properties of the liquid are still lacking. Recently, we studied the leveling of a stepped film: a new nanofluidic tool to study the properties of polymers in thin film geometries [24][25][26][27][28].In this work, we study the leveling of perfec...

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“…The latter assumption allows for a linearisation of the problem and application of Fourier analysis. 4,24 In section II the simulation model and the preparation of the polymer films are described whereas in section III we provide the analytical viscocapillary solution for a periodic square profile. Section IV describes our analysis and the results obtained from the simulation and analytical approaches.…”

Section: Introductionmentioning

confidence: 99%

“…Given the appealing properties such as (in general) low thermal conductivity and high dielectric constant, these systems are utilized in a variety of technological fields such as micro-electronics, 1,2 coatings in optical fibers 3 and nanolithography. 4 To this end, their static and dynamic properties and deviations from bulk behaviour due to spatial restriction and interfacial effects have been the subject of extensive research and debate over the last years. [5][6][7][8] Particular attention has been focused on the rheological behaviour of thin polymer films as well as on the dynamical heterogeneities triggered by the presence of interfaces.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulation of the capillary leveling of viscoelastic polymer films

Tanis

Meyer

Salez

et al. 2017

The Journal of Chemical Physics

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Abstract. Surface tension-driven flow techniques have recently emerged as an efficient means of shedding light into the rheology of thin polymer films. Motivated by experimental and theoretical approaches in films bearing a varying surface topography, we present results on the capillary relaxation of a square pattern at the free surface of a viscoelastic polymer film, using molecular dynamics simulations of a coarse-grained polymer model. Height profiles are monitored as a function of time after heating the system above its glass-transition temperature and their time dependence is fitted to the theory of capillary leveling. Results show that the viscosity is not constant, but time dependent. In addition to providing a complementary insight about the local inner mechanisms, our simulations of the capillary-leveling process therefore probe the viscoelasticity of the polymer and not only its viscosity, in contrast to previous experimental approaches.

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Confinement and flow dynamics in thin polymer films for nanoimprint lithography

Cited by 31 publications

References 29 publications

On using the levelling of the free surface of a Newtonian fluid to measure viscosity and Navier slip length

On using the levelling of the free surface of a Newtonian fluid to measure viscosity and Navier slip length

Relaxation and intermediate asymptotics of a rectangular trench in a viscous film

Molecular dynamics simulation of the capillary leveling of viscoelastic polymer films

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