Simulation study on the template release mechanism and damage estimation for various release methods in nanoimprint lithography

Shiotsu, Takahiro; Nishikura, Naoki; Yasuda, Masaaki; Kawata, Hiroaki; Hirai, Yoshihiko

doi:10.1116/1.4832215

Cited by 22 publications

(14 citation statements)

References 27 publications

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“…Simulations are useful investigation tools for revealing the physics behind the lithography technique and optimizing the NIL process parameters [ 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ]. Computational simulation helps to facilitate a better understanding of the details of the demolding process that may not be easily revealed by experiments (e.g., stress distributions in the resist during demolding), which is essential for optimizing the NIL process.…”

Section: Process Simulations For Nilmentioning

confidence: 99%

“…Figure 3 shows the finite element simulation results at the moment of demolding between a silicon mold and polymethylmethacrylate (PMMA) resists with different Young’s modulus values [ 53 ]. The modeling result shows that the stress is concentrated at the corner of the pattern [ 50 , 55 ], and the resultant stress field is greater in the resists with a larger Young’s modulus ( Figure 3 b) [ 53 ]. Although the friction force which picks up the resist might not be detrimental, pattern fracture could still occur since the micro-cracks may already have been induced during the previous steps [ 50 ].…”

Section: Process Simulations For Nilmentioning

confidence: 99%

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Interfacial Interactions during Demolding in Nanoimprint Lithography

Chen

Luo

et al. 2021

Micromachines

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Nanoimprint lithography (NIL) is a useful technique for the fabrication of nano/micro-structured materials. This article reviews NIL in the field of demolding processes and is divided into four parts. The first part introduces the NIL technologies for pattern replication with polymer resists (e.g., thermal and UV-NIL). The second part reviews the process simulation during resist filling and demolding. The third and fourth parts discuss in detail the difficulties in demolding, particularly interfacial forces between mold (template) and resist, during NIL which limit its capability for practical commercial applications. The origins of large demolding forces (adhesion and friction forces), such as differences in the thermal expansion coefficients (CTEs) between the template and the imprinted resist, or volumetric shrinkage of the UV-curable polymer during curing, are also illustrated accordingly. The plausible solutions for easing interfacial interactions and optimizing demolding procedures, including exploring new resist materials, employing imprint mold surface modifications (e.g., ALD-assisted conformal layer covering imprint mold), and finetuning NIL process conditions, are presented. These approaches effectively reduce the interfacial demolding forces and thus lead to a lower defect rate of pattern transfer. The objective of this review is to provide insights to alleviate difficulties in demolding and to meet the stringent requirements regarding defect control for industrial manufacturing while at the same time maximizing the throughput of the nanoimprint technique.

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Section: Process Simulations For Nilmentioning

confidence: 99%

Section: Process Simulations For Nilmentioning

confidence: 99%

Interfacial Interactions during Demolding in Nanoimprint Lithography

Chen

Luo

et al. 2021

Micromachines

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“…Wang et al studied the stress and deformation behavior in polymer resist during the demolding process in thermal imprint lithography via finite element method [11,12]. Shiotsu et al studied the demolding mechanism using numerical simulation based on fracture mechanics and damage estimation for various demolding methods in NIL [13,14]. However, these research models are mainly about parameter optimization, such as demolding temperature, demolding force, curing degree of polymer, and improvement of imprint pattern structure and demolding method.…”

Section: Introductionmentioning

confidence: 99%

Effects of Adhesion Force of Mold Surface on Imprinted Polymer Deformation

Wang

Zhang

et al. 2016

J. Photopol. Sci. Technol.

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Anti-sticking treatment of the mold is crucial to improve pattern transferring fidelity in nano-imprint lithography. It is an important issue to investigate the effects of the antisticking layer on pattern transferring while considering the actual effectiveness of the antisticking layer after mold is used repeatedly. In this paper, contact separating between mold and polymer under different adhesion force conditions was investigated. According to displacement nephograms of polymer in different demolding stages and the relationship curves between demolding force and demolding displacement, the development of polymer deformation was compared and analyzed. The effect of increasing adhesion force on demolding force and pattern maximum stretch was studied. It is shown that complete failure of antisticking layer at the top would increase the second peak value of demolding force and stretch deformation of polymer pattern, accompanied by severe necking phenomenon. After complete separation of the lateral contact at the top, imprinted polymer patterns have obvious deformation. It is found that the second peak value of demolding force and polymer pattern maximum stretch have linear relationship with decreasing antisticking layer effectiveness at the top.

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“…Due to the difference of the thermal elastic deformation, there will be lateral strain applied to the polymer pattern during the cooling and demolding process [13][14][15][16]. In addition, when the mold is removed with an inclined angle normal to the substrate, as is the case for the peeling and roll-to-roll processes, the resist suffers a lateral force from the template and bending strain is induced [17].…”

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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Simulation study on the template release mechanism and damage estimation for various release methods in nanoimprint lithography

Cited by 22 publications

References 27 publications

Interfacial Interactions during Demolding in Nanoimprint Lithography

Interfacial Interactions during Demolding in Nanoimprint Lithography

Effects of Adhesion Force of Mold Surface on Imprinted Polymer Deformation

Analysis of Debonding Problem during Demolding Process of Nanoimprinting

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