STUDY OF A LITHOGRAPHY TECHNIQUE WITH LOW COST BY NANO-HEAT SPOT

点击翻译按钮获取中文摘要

In this project, we focused on the phenomenon of nano-scale heating. The development of a fabrication technique (referred to here as thermal lithography) and the elucidation of the super-resolution readout mechanism were carried out. Light intensity inside a focused laser spot has a Gaussian profile and the temperature distribution induced by it has also a similar profile. Therefore, a high temperature area with sub-wavelength dimensions can be generated in the center of the focused laser spot. Physical or chemical reactions induced by heating can be confined inside this region. This phenomenon is useful for fabricating nano-scale structures and is integrally related to the super-resolution readout mechanism. We succeeded in producing minute dots 50 nm in diameter and with a spacing of 50 nm using a sample consisting of TbFeCo and ZnS-SiO_2. These dimensions and spacing were approximately one sixth of the optical diffraction limit. Additionally, advanced carbon nano tube(CNT) probes were developed for the observation of the fabricated structures in detail. The adoption of a base probe with a blunt apex and setting the CNT length to approximately 200 nm lead to better durability and lower noise in comparison with conventional CNT probes. The mechanism of super-resolution readout was believed to be related to the optical near-field or surface plasmons, however, it is clear from this study that nano-scale heating plays an important role in the mechanism, and the role of the each layer within the device structure was clarified. These results lead to a breakthrough in the development of super-resolution optical disks. In the future, application of thermal lithography to semiconductor fabrication as well as further clarifying the super-resolution readout mechanism and developing a temperature measurement system will be carried out.