Since 1960s, the number of transistors in an integrated circuit has roughly doubled every two years, showing exponential growth in the capabilities of electronic devices. This tendency has been sustained over the past several decades on the basis of continuous advancements in manufacturing technologies including optical lithography. However, photolithography is reaching a physical limit in resolution and thus, alternative technologies such as extreme ultraviolet (EUV) lithography, nanoimprint lithography, interference lithography and directed self-assembly (DSA) are rapidly emerging.
DSA of block copolymers (BCPs) has recently attracted much attention as a promising candidate for the next-generation lithography due to its capacity to provide excellent resolution and scalability. The self-assembly of BCPs, two mutually incompatible polymer chains connected via covalent bonding, can create sub-10 nm periodic patterns with different geometries such as dots, lines, holes, and rings, while even more complex features such as bends, T-junctions, and jogs have already been demonstrated. Based on these promising results, our research efforts have focused on resolving remaining challenges for DSA such as control over defects, resolution, and throughput for next-generation lithography with sub-10 nm resolution.
Warm solvent annealing 
Cold spin-casting 
Immersion-induced annealing
Further reading
“Spontaneous Registration of Sub-10 Nanometer Features Based on Sub-Zero-Celsius Spin-Casting of Self-Assembling Building Blocks Directed by Chemically-Encoded Surfaces” ACS Nano, August 2018, 12(8), pp. 8224-8233 Jung Hye Lee, Hak-Jong Choi, ChulHee Lee, Seung Won Song, Joong Bum Lee, Daihong Huh, Yoon Sung Nam, Duk Young Jeon, Heon Lee*, and Yeon Sik Jung* [Link]
“Eliminating the Trade-Off between the Throughput and Pattern Quality of Sub-15 nm Directed Self-Assembly via Warm Solvent Annealing” Advanced Functional Materials, 2015, 25, 2, 306-315 Jong Min Kim, Yong Joo Kim, Woon-Ik Park, Yoon Hyung Hur, Jae Won Jeong, Dong Min Sim, Kwang-Min Baek, Jung Hye Lee, Mi-Jeong Kim, and Yeon Sik Jung* [Link]
“Deep-Nanoscale Pattern Engineering by Immersion-Induced Self-Assembly” ACS Nano, 2014, 8, 10, 10009-18 Woon Ik Park, Jong Min Kim, Jae Won Jeong, and Yeon Sik Jung* [Link]
“Solvent vapor induced tunability of self-assembled block copolymer patterns” Advanced Materials, Volume 21, 2009, Pages 2540-2544 Yeon Sik Jung and Caroline A. Ross [Link]