Problems of the nanoimprinting technique for nanometer scale pattern definition

Scheer, Hella-Christin; Schulz, H.; Hoffmann, T.; Torres, C. M. Sotomayor

doi:10.1116/1.590436

Cited by 160 publications

(59 citation statements)

References 13 publications

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“…(2). For another, the rate is strongly dependent on the film thickness, for which the original Poiseuille formulation cannot provide any information.Although nanoscopic and microscopic patterning of surfaces is drawing considerable interest that involves capillarity, 5,6,8,9 there has been no suitable model that can explain the rate of capillary rise of fluids under confined geometry on a micro-and nano-scale. In this letter, we develop a Poiseuille model to explain the capillary kinetics of polymer melt in microcavities and compare the model with experimental data.…”

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confidence: 99%

“…A typical example for this situation can be found in nanoimprint lithography if negative molds are used. 6 The third is one in which the mold is highly permeable and the film thickness is sufficiently large and the equation reduces to…”

mentioning

confidence: 99%

“…A similar situation can be found in high temperature nanoimprint lithography if a negative mold is used. 6 For a smooth, uniform (laminar) flow of a fluid in a narrow cylindrical tube, which is the classical capillary system, the Poiseuille equation can be used to relate the volumetric flow rate to various characteristics of the fluid and the capillary system. The volumetric flow rate, dV / dt, is given by…”

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Capillary Kinetics of Thin Polymer Films in Permeable Microcavities

Suh

2007

MRS Proc.

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We present a Poiseuille model that can explain the rate of capillary rise of thin polymer films in permeable microcavities. In comparison to the traditional Poiseuille formulation, two features of the system were considered: the permeable nature of the enclosure and the effect of thin polymer films that are confined to the substrate. The model predicts that the rate is inversely proportional to the channel width, contrary to what the original Poiseuille model predicts, and it is proportional to the initial film thickness, which the original model cannot account for. Capillarity is involved in many practical systems such as wetting and repellency of woven fibers, paper products, and porous solids, wicking, and cleaning action in detergent baths.1 Above all, the capillary flow of molten polymers has been extensively studied in plastics because the polymer melt is often accompanied by instabilities called "melt fracture" in extrusion process.2 At very high shear stress, polymer melt flows violate the classical no-slip hydrodynamic boundary condition at solid surfaces, and exhibit nonNewtonian and complex nonlinear dynamics, which often leads to the instabilities. However, the polymer melt can be regarded as a Newtonian fluid and the no-slip boundary condition can be applied if the shear rate is sufficiently small. 4 A typical example is capillary force lithography (CFL), which has recently been developed for patterning polymers above their glass transition temperatures.5 When a patterned PDMS mold is placed on a polymer film spin-coated onto a substrate and heated above the glass transition temperature, capillarity forces the polymer melt into the void of the channel. In contrast to the "forced" capillary flow in the conventional extrusion process, the flow in this case is "spontaneous" without any external force. In this spontaneous flow, the rate of capillary rise is very small due to the high viscosity of polymer melt and the shear rate is accordingly small. A similar situation can be found in high temperature nanoimprint lithography if a negative mold is used. 6For a smooth, uniform (laminar) flow of a fluid in a narrow cylindrical tube, which is the classical capillary system, the Poiseuille equation can be used to relate the volumetric flow rate to various characteristics of the fluid and the capillary system. The volumetric flow rate, dV / dt, is given bywhere r is the radius of the tube, is the viscosity of the fluid, z is the distance of fluid movement in the tube in time, t, and P is the pressure drop across the distance z. In Eq.(1), the polymer melt is a Newtonian fluid and the no-slip boundary condition is used. In the original Poiseuille formulation, the pressure drop, P, is replaced by Laplace pressure ͑=␥ cos / L͒, which yieldswhere L is the half channel width, ␥ is the surface tension of the polymer, and is the equilibrium contact angle at the three-phase contact line. Our experiments revealed that the original Poiseuille formulation fails when it is applied to the capillary rise of thin polymer me...

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Capillary Kinetics of Thin Polymer Films in Permeable Microcavities

Suh

2007

MRS Proc.

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“…A similar situation can be found in high temperature nanoimprint lithography when a negative mold is used. 30 It has been shown that, for a given mold geometry, the height of nanostructure is tunable by changing the annealing time. Also the tip shape can be rounded or dimpled depending on the temperature as a result of reflows of polymer melt.…”

Section: Discussionmentioning

confidence: 99%

Capillarity-assisted fabrication of nanostructures using a less permeable mold for nanotribological applications

Suh

Jeong

Kim

et al. 2006

Journal of Applied Physics

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A simple kinetic model is presented to describe the capillary rise of a thin polymer film into a less permeable polyurethane acrylate mold. In this model, capillarity is explained by the competition between capillary and hydrodynamic forces in the course of pattern formation. For a less permeable mold, it was found that the capillary rise increases linearly with time. In addition, the contribution of viscosity and film thickness disappears such that the kinetics is solely governed by the permeation kinetics and capillary force. The present model would be useful to describe the evolution of molded nanostructures when a less permeable mold material other than polydimethylsiloxane is used for the patterning. Moreover, nanostructures with different tip shapes ͑rounded or dimpled͒ were observed depending on the fabrication temperature. The structures were tested for potential nanotribological applications such as reduction in adhesive and friction forces.

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“…The patterned structures are obtained after the stamp is released. Defects in the form of incomplete pattern transfer may occur due to high viscosity of polymer resist and the complexity of stamp pattern [6][7][8]. Otherwise, failure in the type of peeling of patterns frequently occurs due to adhesion between the stamp and the resin in the stamp-releasing process [9].…”

Section: Introductionmentioning

confidence: 99%

Molecular simulation study on adhesions and deformations for Polymethyl Methacrylate (PMMA) resist in nanoimprint lithography

Kwon¹,

Lee²,

Park³

et al. 2011

J Mech Sci Technol

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The NIL (nanoimprint lithography) process is explored through numerical simulation, utilizing MD (molecular dynamics), with a focus on the resin deformations and the adhesion between the resin material and the tool. For the force-field of the Polymethyl Methacrylate (PMMA), used for the resin material, a united atom model is employed. For temperature control in the MD simulation, the recursive multiple chains of the Nosé-Poincaré thermostat is applied. The deformation and adhesion in the NIL process are explored from the mechanics viewpoint based on the present MD results. In particular, the adhesion behavior of a self-assembly monolayer (SAM) in the stamp-releasing stage is discussed in connection with the monolayer thickness.

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Problems of the nanoimprinting technique for nanometer scale pattern definition

Cited by 160 publications

References 13 publications

Capillary Kinetics of Thin Polymer Films in Permeable Microcavities

Capillary Kinetics of Thin Polymer Films in Permeable Microcavities

Capillarity-assisted fabrication of nanostructures using a less permeable mold for nanotribological applications

Molecular simulation study on adhesions and deformations for Polymethyl Methacrylate (PMMA) resist in nanoimprint lithography

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