Dr. Bongkeun Kim Profile

Dr. Bongkeun Kim

at Materials Research Lab

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Author

Publications (7)

Proceedings Article | 27 March 2015 Paper

Barriers to defect melting in chemo-epitaxial directed self-assembly of lamellar-forming diblock copolymer/homopolymer blends

Kenichi Izumi, Bongkeun Kim, Nabil Laachi, Kris Delaney, Michael Carilli, Glenn Fredrickson

Proceedings Volume 9423, 94232C (2015) https://doi.org/10.1117/12.2085685

KEYWORDS: Polymers, Neodymium, Roentgenium, Toxic industrial chemicals, Ions, Industrial chemicals, Lithography, Double patterning technology, Lithium, Directed self assembly

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SPIE Journal Paper | 5 February 2015

Effects of thermal fluctuations on directed self-assembly in cylindrical confinement

Nabil Laachi, Tatsuhiro Iwama, Kris Delaney, Bongkeun Kim, Robert Bristol, David Shykind, Corey Weinheimer, Glenn Fredrickson

JM3, Vol. 14, Issue 01, 013505, (February 2015) https://doi.org/10.1117/12.10.1117/1.JMM.14.1.013505

KEYWORDS: Polymethylmethacrylate, Thermal effects, Critical dimension metrology, Error analysis, Lithography, Overlay metrology, Picosecond phenomena, Polymers, Directed self assembly

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Proceedings Article | 28 March 2014 Paper

Field-theoretic simulations of directed self-assembly in cylindrical confinement: placement and rectification aspects

Nabil Laachi, Tatsuhiro Iwama, Kris Delaney, Bongkeun Kim, Robert Bristol, David Shykind, Corey Weinheimer, Glenn Fredrickson

Proceedings Volume 9049, 90491M (2014) https://doi.org/10.1117/12.2046472

KEYWORDS: Polymethylmethacrylate, Error analysis, Thermal effects, Critical dimension metrology, Cadmium, Lithography, Computer simulations, Picosecond phenomena, Polymers, Directed self assembly

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Proceedings Article | 28 March 2014 Paper

Computational studies of shape rectification in directed self-assembly

Tatsuhiro Iwama, Nabil Laachi, Kris Delaney, Bongkeun Kim, Glenn Fredrickson

Proceedings Volume 9049, 904927 (2014) https://doi.org/10.1117/12.2046187

KEYWORDS: Charge-coupled devices, Polymethylmethacrylate, Critical dimension metrology, Lithography, Bridges, Analytical research, Optical lithography, Cadmium, Diamond, Directed self assembly

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Proceedings Article | 28 March 2014 Paper

Directed self-assembly of diblock copolymers in laterally confining channels: line-edge-roughness and defectivity

Bongkeun Kim, Nabil Laachi, Kris Delaney, Glenn Fredrickson

Proceedings Volume 9049, 90491D (2014) https://doi.org/10.1117/12.2045774

KEYWORDS: Roentgenium, Line edge roughness, Wave propagation, Surface roughness, Phase shifts, Thermal effects, Polymers, Lithography, Bohrium, Directed self assembly

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The directed self-assembly (DSA) of diblock copolymers in laterally confining channels is a promising avenue to produce line-and-space patterns with a sub-25 nm pitch. In this study, we use self-consistent field theory (SCFT) to investigate the DSA of both cylinder- and lamella-forming diblock copolymers in narrow trenches with corrugated sidewalls. Specifically, we focus on systems that form lying-down cylinder monolayers or standing-up lamellae parallel to the sidewalls of the channel. While previous experimental and computational studies highlighted well-ordered cylinders and lamellae in smooth channels, undesirable defective structures are also observed. In the present study, the wetting sidewalls of the channels are no longer planar surfaces. Rather, we consider undulating sidewalls and investigate the effect of the rough surfaces on defectivity and line edge roughness (LER) in the self-assembled morphologies. We use SCFT to investigate the formation free energy of isolated, meta-stable defects of both cylindrical and lamellar block copolymers inside channels with sinusoidal corrugations along the sidewalls. Parametric studies include the effects of the amplitude and the frequency of the sinusoidal wall shape function, the placement of the defect core, as well as the number of cylinders and lamellae in channels of varying widths. Our simulations indicate that the relative decreases in defect formation energy in rough channels compared to smooth channels are strikingly similar in both cylinder- and lamella-forming melts. Furthermore, using a suitable order parameter and the center-to-center displacement of the self-assembled lines, our complex Langevin (CL) simulations (beyond SCFT) show that the propagation of the LER is sensitive to the amplitude and the wavelength of the sidewall shape function, with an even stronger dependence in the lamellar case compared to the cylindrical case. More broadly, our study reveals the dependence of line edge roughness propagation on a wide range of parameters that must be carefully controlled in order to successfully implement a directed self-assembly process with block copolymers.

Proceedings Article | 26 March 2013 Paper

The hole shrink problem: Theoretical studies of directed self-assembly in cylindrical confinement

Nabil Laachi, Kris Delaney, Bongkeun Kim, Su-Mi Hur, Robert Bristol, David Shykind, Corey Weinheimer, Glenn Fredrickson

Proceedings Volume 8680, 868014 (2013) https://doi.org/10.1117/12.2011198

KEYWORDS: Polymethylmethacrylate, Picosecond phenomena, Critical dimension metrology, Lithography, Molecular self-assembly, Polymers, Optical lithography, Cadmium, Analytical research, Directed self assembly

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Proceedings Article | 26 March 2013 Paper

Defectivity study of directed self-assembly of cylindrical diblock copolymers in laterally confined thin channels

Bongkeun Kim, Nabil Laachi, Glenn Fredrickson

Proceedings Volume 8680, 868016 (2013) https://doi.org/10.1117/12.2011178

KEYWORDS: Roentgenium, Electron beam lithography, Polymers, Analytical research, Optical lithography, Thin films, Chemistry, Systems modeling, Computer simulations, Directed self assembly

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Showing 5 of 7 publications

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