The other interest of our group lies in the fabrication of designed 2D patterned surfaces for its applications to microelectronic, optoelectronic and magnetic recording devices, and biochips/sensors. The methods of fabrication include soft-lithography such as microcontact printing, replica molding, and nanoimprinting, as well as advanced lithographic techniques such as E-beam, X-ray, and ion beam lithography. Although these lithographic techniques based on 'top-down approach' are very useful in the pattern fabrication for submicron-scale patterns, they are limited in cost and processing time. Self-assembly 'bottom-up' approaches are alternative methods in the simple control of the pattern size and low-cost parallel processes. Recently, cost-effective hybrid fabrication processes have been developed to fabricate designed patterns using soft lithography in combination with the self-assembly of colloidal nanospheres, block copolymers, and surfactants.
In particular, thin films of self-organized nanosphere array or block copolymers have considerable attention because of their potential application as templates or masks for the nanolithographic fabrication of magnetic and electronic media materials and devices. In our group, ordered nanopatterns with the feature-size in the range of 15-100 nm have been successfully organized by using nanosphere and block copolymer lithographic fabrications. The self-assembled nanopatterns that are transferred onto silicon wafer substrate can be modified simply by the reactive ion etching (RIE) or ion milling. For the memory device applications, spintronic substances are impregnated into the patterned substrate as isolated nanoscopic domains. In addition, the self-assembly route of nanopattern formation has a number of applications including DNA chip, storage memory device, low-k materials, and advanced nano-lithography.