The Study Of Novel Nanoimprint Resists And Their Applications

There has been a thriving development in nanotechnology since its appearance in the 1950s. People have shown great enthusiasm in the study of the materials and structures with nanoscale. Therefore, various nanofabrication techniques such as photolithography, focused ion beam technique, e-beam lithography, nanoimprint lithography and self-assembly methods arose and developed continuously. Among them, nanoimprint lithography has drawn a great number of interests due to its advantages in fabricating nanopatterns with high throughput, high resolution and low cost. It has become one of the main nanofabrication methods in laboratories, as well as has been applied in industry preliminarily.Nanoimprint resists, one of the key elements in nanoimprint lithography, are widely used in thermal nanoimprint, UV-curable nanoimprint and soft lithography. According to the types of nanoimprint, the resists can be classified into two groups:thermal nanoimprint resists and UV-curable nanoimprint resists. In the present time, PMMA and PS are commonly used thermal resists, although there are still some disadvantages. Photoinitiators in the UV-curable resists based on cationic polymerization are mainly photo acid generators, which may lead to corrosion of imprint resists or substrates by generating acidic materials after UV exposure. Basing on the demands of solving such problems, we synthesize a novel thermoplastic polymer and photobase generator which can be used as thermal nanoimprint resists and photoinitiator in UV-curable resists, respectively.The synthesis of poly (isobornyl methacrylate) (PIBMA) and its application in nanoimprint. free radical polymerization We synthesized PIBMA with different molecular weights through radical polymerization by controlling the amount of the initiator. The thermal decomposition temperature and glass transition temperature of all the PIBMAs were measured so as to be used as imprint resists. The replication of nanopatterns with sub-50 nm was demonstrated by imprint with the PIBMA. Besides, the comparisons among PIBMA, PMMA and PS were carried out in mechanical strength, etching resistance and lift-off performance, respectively.The application of PIBMA in enhancing optical transmission. Sapphire was used as the display screen because of its high mechanical strength, high thermal and chemical stability and good optical transmittance. However, the optical transmission of sapphire is still limited (65% to 75%) in the visible region. The synthetic PIBMA has excellent optical transmission during the visible region. Therefore, we introduced the PIBMA with photonic crystal structures to enhance the optical transmission of sapphire by nanoimprint lithography.The synthesis of photobase generator and its application. Photoinitiators used in the UV-curable resists are mainly photo acid generators that could lead to corrosion of imprint resists or substrates by generating acidic materials after UV exposure. Photobase generator also can be used as photoinitiators with the advantage of avoiding such problems of photo acid generators. However, there are less reports on photobase generators applied in UV-curable nanoimprint resists. We synthesized the QA salt I-S, one of the photobase generators, as well as studied its performance used as photoinitiator in UV-curable resists by hybrid nanoimprint soft lithography (HNSL).