Simulation of the template release process based on fracture mechanics in nanoimprint lithography

Shiotsu, Takahiro; Uemura, Kimiaki; Tochino, Takamitsu; Ooi, Shuuya; Ônishi, Yoshihiro; Yasuda, Masaaki; Kawata, Hiroaki; Kobayashi, Takuya; Hirai, Yoshihiko

doi:10.1016/j.mee.2014.05.023

Cited by 8 publications

(6 citation statements)

References 22 publications

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“…With such large features as those needed for micromolding, patterned coatings can be deformed due to the strong adhesion between the coating and the mold in the presence of interfacial microstructures; demolding may even fail, resulting in permanent contamination of the mold. It has been shown at the nanoscale that coatings with low surface energies will reduce demolding-related defects, , and investigations of the demolding force have shed light on this aspect of the nanoimprinting processes (where the whole mold is separated from a nanostructured coating in a normal separation direction). − …”

Section: Introductionmentioning

confidence: 99%

Modulus- and Surface-Energy-Tunable Thiol–ene for UV Micromolding of Coatings

Sakizadeh

Weiblen

et al. 2017

ACS Appl. Mater. Interfaces

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Micromolding of UV-curable materials is a patterning method to fabricate microstructured surfaces that is an additive manufacturing process fully compatible with roll-to-roll systems. The development of micromolding for mass production remains a challenge because of the multifaceted demands of UV curable materials and the risk of demolding-related defects, particularly when patterning high-aspect-ratio features. In this research, a robust micromolding approach is demonstrated that integrates thiol-ene polymerization and UV LED curing. The moduli of cured thiol-ene coatings were tuned over 2 orders of magnitude by simply adjusting the acrylate concentration of a coating formulation, the curing completed in all cases within 10 s of LED exposure. Densely packed 50-μm-wide gratings were faithfully replicated in coatings ranging from soft materials to stiff highly cross-linked networks. Further, surface energy was modified with a fluorinated polymer, achieving a surface energy reduction of more than a half at a loading of 1 wt %, and enabling tall (100 μm) defect-free patterns to be attained. The demolding strengths of microstructured coatings were compared using quantitative peel testing, showing its decrease with decreasing surface energy, coating modulus, and grating height. This micromolding process, combining tunability in thermomechanical and surface properties, makes thiol-ene microstructured coatings attractive candidates for roll-to-roll manufacture. As a demonstration of the utility of the process, superhydrophobic surfaces are prepared using the system modified by the fluorinated polymer.

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Section: Introductionmentioning

confidence: 99%

Modulus- and Surface-Energy-Tunable Thiol–ene for UV Micromolding of Coatings

Sakizadeh

Weiblen

et al. 2017

ACS Appl. Mater. Interfaces

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“…1. Other defects, reported in the literature, consist of broken mold structures/features, such as fracture, delamination [19,20] and debond [1]. Adhesion and friction forces significantly affect the pattern transfer.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Debonding Problem during Demolding Process of Nanoimprinting

Wang

Zhang

et al. 2017

J. Photopol. Sci. Technol.

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Template release process during nanoimprint lithography was investigated, and the detailed steps of this process were described in order to reduce defects caused by demolding process. The debonding problem was discussed by using optimization of model, numerical simulation and theoretical analysis. The rules and mechanism of debonding were obtained by analyzing the relations between the bonding strength and the vertical stresses of the cementing surface linking the residual layer and the substrate in terms of stress balance theory in fracture mechanics. The location and demolding process which is prone to debond were analyzed. It is concluded that the debonding phenomenon took place at the intermediate position during the second demolding stage, when the adhesion force between the resist and the mold was 0.8 times of other interfaces between the mold and the resist. The debonding phenomenon took place at the angular position during the fourth demolding stage, when the adhesion force between the resist and the mold was 1.2 times bigger than the other interfaces between the mold and the resist.

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“…Finally, the mold is separated from the resist during demolding and the fine pattern on the mold is transferred to the resist [5]. In the demolding process, microstructure deformations and even fracture defects are often induced because of the adhesion between the mold and the resist [6]. The deformations and defects will lead to quality reduction of the replica and contamination of the mold.…”

Section: Introductionmentioning

confidence: 99%

Effects of Friction Coefficient and Cohesion between a Mold and a Polymer Resist during Demolding Process in Hot Embossing

Zhang

Wang

Zheng

et al. 2016

J. Photopol. Sci. Technol.

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Pattern fidelity in hot embossing is influenced to a large extent by defects induced with mold releasing from polymer resist. It is necessary to investigate contact properties of interface between the mold and the polymer resist during demolding process. In this paper, influences of friction coefficient and cohesion on deformation in the polymer resist during the demolding are studied via finite element method. An optimization finite element model with nickel mold/polymer resist structure was constructed, considering both mechanical properties of the polymer resist and optimal element number. Simulation results show that there exist the optimum friction coefficient and the optimum cohesion allowing the deformation of the polymer resist to be minimal. These optimum contact properties can be applied in guiding selections of material and improving quality of embossed patterns.

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Simulation of the template release process based on fracture mechanics in nanoimprint lithography

Cited by 8 publications

References 22 publications

Modulus- and Surface-Energy-Tunable Thiol–ene for UV Micromolding of Coatings

Modulus- and Surface-Energy-Tunable Thiol–ene for UV Micromolding of Coatings

Analysis of Debonding Problem during Demolding Process of Nanoimprinting

Effects of Friction Coefficient and Cohesion between a Mold and a Polymer Resist during Demolding Process in Hot Embossing

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