Deformation Mechanism and Punch Taper Effects on Nanoimprint Process by Molecular Dynamics

Hsu, Quang‐Cherng; Wu, Chen‐Da; Fang, Te-Hua

doi:10.1143/jjap.43.7665

Cited by 43 publications

(28 citation statements)

References 12 publications

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“…Figure 4(e) shows a snapshot during the separation process. Large amount of springback, which was reported earlier in both experiment [13] and simulation [26], is clearly observed where the stamp imprints. According to the previous studies, the relaxation of the compressive residual stress, the adhesive force between the stamp and the polymer film, the elastic deformation of the stamp or any combinations of these three may be responsible for this springback phenomenon [13,27].…”

Section: Resultssupporting

confidence: 78%

“…MD simulation is a powerful tool and has been used for the analysis of nanoscale systems, such as thin film lubrication [17][18][19], nanoindentation [20][21][22], and nanoscale friction [23][24][25]. Recently, MD simulation of NIL using a nickel stamp and a copper substrate was reported, in which the deformation mechanism and stamp taper effects were investigated by changing a taper angle [26]. The deformation behavior of a polymer film was also analyzed through MD simulation using a diamond stamp and an amorphous poly-(methylmethacrylate) (PMMA) film [27].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Molecular dynamics study of pattern transfer in nanoimprint lithography

Kang

Kim

2007

Tribol Lett

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“…5i). As a result, resist shape is changed from rectangular into trapezoidal [21][22][23]. This can be attributed to the relaxation of polyethylene molecules upon removal of the compression force.…”

Section: Simulation Of Nil Processmentioning

confidence: 99%

Molecular Dynamic Studies on Deformation of Polymer Resist During Thermal Nano Imprint Lithographic Process

Woo

Lee

2009

Tribol Lett

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Molecular dynamic simulation of nano imprint lithography (NIL) in which nanoscale patterned stamp is pressed onto amorphous polyethylene (PE) surface is performed to study the deformation behavior of polymer resist. Force fields including bond, angle, torsion, and Lennard Jones potential are used to describe the intermolecular and intra-molecular forces of PE molecules and stamp. Periodic boundary condition is used in horizontal direction and canonical NVT ensemble is employed to control the system temperature. Using the simulation results, the behavior of polymer resist is investigated during the imprinting process. The mechanism of resist deformation is analyzed by considering various parameters including the surface geometry, atom distribution, and density. Especially, the density in the bottom (emboss) region is found to be larger than the top (cavity) region due to compression of polymer molecules. The result indicates that small scale patterning of polymer resist largely depends on compression rather than the flow of molecules. The numerical results are compared with the local density measurement data using the atomic force microscope (AFM). They exhibit a similar behavior at least in a qualitative sense. Additional simulations, where the stamp geometry and molecular mobility are varied and are performed to investigate the deformation characteristics of polymer resist. From these simulations, important elements for understanding of NIL process are obtained.

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“…The details of the scheme of MD analysis can be found in previous studies by the authors Refs. [11][12][13][14]. These earlier works examined several key variables in a NIL process for single crystal of copper and alloys made of face-centered cubic (fcc) structures: temperature, stamping speed, taper angle, composition, and annealing, etc.…”

Section: Introductionmentioning

confidence: 99%

Nanoimprint Lithography Simulation of the Polymer Chains (CH2)n with Anti-Adhesion Layer on Stamp by Molecular Dynamics Method

Hsu¹,

Lin²,

Wu³

et al. 2012

Jnl of Comp & Theo Nano

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This paper aims at the study of nanoimprint lithography (NIL) of the polymer material in (CH 2 ) n chains using molecular dynamics (MD) simulation method. The effects of the stamp tip width, temperature and spring back were examined for stamps with and without anti-adhesion layer, a selfassembled monolayer (SAM). The MD simulation codes were built to simulate material deformation behaviors at atomic scale. The deformation mechanism of NIL using silicon stamp without SAM anti-adhesion layer coating was first studied, and then simulations of the NIL processes with SAM coating were done to compare with those without SAM anti-adhesion layer. NIL at three different temperatures, 0 K, 273 K and 300 K, were studied to understand the temperature effects on NIL. Without SAM coating on the stamp, adhesion of polymer chains to the stamp tip occurred at 273 K and 300 K. This adhesion problem prevented the pattern from being successfully transferred. With the stamp tip coated with SAM, however, by reducing the stamp tip width and increasing imprinting depth the adhesion problem can be avoided to ensure successful pattern transfer.

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Deformation Mechanism and Punch Taper Effects on Nanoimprint Process by Molecular Dynamics

Cited by 43 publications

References 12 publications

Molecular dynamics study of pattern transfer in nanoimprint lithography

Molecular dynamics study of pattern transfer in nanoimprint lithography

Molecular Dynamic Studies on Deformation of Polymer Resist During Thermal Nano Imprint Lithographic Process

Nanoimprint Lithography Simulation of the Polymer Chains (CH<SUB>2</SUB>)<SUB><I>n</I></SUB> with Anti-Adhesion Layer on Stamp by Molecular Dynamics Method

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