Dr. Suh earned his BS from the School of Chemical and Biological Engineering (2005) and PhD from the Interdisciplinary Program of Nano Science and Technology (2011) at Seoul National University under the direction of Professor Kookheon Char, where he investigated the tunability of surface energy using thermally cured organosilicates. He first began working as a postdoc for Paul Nealey in the Department of Chemical and Biological Engineering at the University of Wisconsin-Madison, and later moved to the Pritzker School of Molecular Engineering at the University of Chicago.
The directed self-assembly (DSA) process, which integrates self-assembling block copolymer (BCP) films with lithographically pre-defined templates, has been extensively researched as an alternative patterning technique to enhance the resolution beyond the limitation of current technology. This approach, already demonstrated with experiments at the laboratory scale, has now started to move to the line in the commercial manufacturing process. In spite of the significant progress to date in DSA technology, there are still several challenges remaining.
The more well-established BCP DSA process was developed around the principle of thermal annealing, which is the most reliable pathway to induce the self-assembly of block copolymers. Unfortunately, this method only works for the special case where the surface energies of each block are similar at the annealing temperature so both blocks are exposed on the free surface during assembly. Poly(styrene-b-methyl methacrylate), or PS-b-PMMA, meets this criterion but is restricted in its use because the smallest feature size realized by PS-b-PMMA is known as the neighborhood of 20 nm.
Seeking block copolymer systems other than PS-b-PMMA is therefore one of the key issues in further reducing the feature size down to the sub-10 nm scale. However, most other block copolymers exhibit a sizeable difference in surface energy between the blocks, especially for those materials with the properties allowing for formation of smaller features. In this case, the block with the lower surface energy tends to segregate to the free surface of films and precludes the assembly of the desired through-film perpendicularly oriented structures. Dr. Suh is actively investigating many different techniques to identify feasible solutions for realization of sub-10 nm scale features, based on his knowledge of polymer physics and interfaces.
Directed self-assembly of block copolymer films on atomically-thin graphene chemical patterns
Chang, TH; Xiong, SS; Jacobberger, RM; Mikael, S; Suh, HS; Liu, CC; Geng, DL; Wang, XD; Arnold, MS; Ma, ZQ; Nealey, PF. Directed self-assembly of block copolymer films on atomically-thin graphene chemical patterns. Scientific Reports. 2016. Vol. 6, Pg. 31407.
Effect of Stereochemistry on Directed Self-Assembly of Poly(styrene-b-lactide) Films on Chemical Pat
Li, X; Liu, YD; Wan, L; Li, ZL; Suh, H; Ren, JX; Ocola, LE; Hu, WB; Ji, SX; Nealey, PF. Effect of Stereochemistry on Directed Self-Assembly of Poly(styrene-b-lactide) Films on Chemical Pat. ACS Macro Letters. 2016. Vol. 5, Pg. 396-401.
Characterization of the shape and line-edge roughness of polymer gratings with grazing incidence sma
H. S. Suh, X. Chen, P. A. Rincon-Delgadillo, Z. Jiang, J. Strzalka, J. Wang, W. Chen, R. Gronheid, J. J. de Pablo, N. Ferrier, M. Doxastakis and P. F. Nealey. Characterization of the shape and line-edge roughness of polymer gratings with grazing incidence sma. Journal of Applied Crystallography. 2016. Vol. 49, Pg. 823-834.
Three-Tone Chemical Patterns for Block Copolymer Directed Self Assembly
Williamson, LD; Seidel, RN; Chen, XX; Suh, HS; Delgadillo, PR; Gronheid, R; Nealey, PF. Three-Tone Chemical Patterns for Block Copolymer Directed Self Assembly. ACS Applied Materials & Interfaces. 2016. Vol. 8, Pg. 2704-2712.
Perpendicularly Aligned, Anion Conducting Nanochannels in Block Copolymer Electrolyte Films
Arges, CG; Kambe, Y; Suh, HS; Ocola, LE; Nealey, PF. Perpendicularly Aligned, Anion Conducting Nanochannels in Block Copolymer Electrolyte Films. Chemistry of Materials. 2016. Vol. 28, Pg. 1377-1389.
Molecular Transfer Printing of Block Copolymer Patterns over Large Areas with Conformal Layers
T. Inoue, D.W. Janes, J. Ren, H.S. Suh, X. Chen, C.J. Ellison and P.F. Nealey. Molecular Transfer Printing of Block Copolymer Patterns over Large Areas with Conformal Layers. Advanced Materials Interfaces. 2015. Vol. 2.
Characterizing the Three-Dimensional Structure of Block Copolymers via Sequential Infiltration Synth
Segal-Peretz, T.; Winterstein, J.; Doxastakis, M.; Ramirez-Hernandez, A.; Biswas, M.; Ren, J.; Suh, H.S.; Darling, S.B.; Liddle, J.A.; Elam, J.W.; de Pablo, J.J.; Zaluzec, N.J.; Nealey, P.F.. Characterizing the Three-Dimensional Structure of Block Copolymers via Sequential Infiltration Synth. ACS Nano. 2015. Vol. 9, Pg. 5333–5347.