Optical Disk Mastering Using Optical Super Resolution Effect
Han-Ping D. Shieh
|關鍵字:||超解析;雷射微影;光碟母模;繞射極限;光阻;雷射刻版;optical super resolution;lithography;mastering;diffraction limit;photoresist;Laser beam recorder|
The objective of this research is to study an innovative lithography using the effect of thermal-induced super resolution, and to demonstrate that the technique can effectively reduce the exposed pit width on the photoresist layer. The technique makes use of a thin metallic mask layer deposited on the top of the photoresist layer. After illuminating with a focused laser beam, the mask layer opens an aperture in melting temperature area around the center of the laser spot. Because the aperture size is much smaller than the laser spot and the optical properties of solid mask layer are different from those of melting one, the intensity distribution of the transmission light would become narrower than that of the incident light and forms a below-diffraction-limit spot size. Our experimental processes were based on the commercial CD mastering procedure and added a mask layer deposited by evaporation. Indium thin film with a range of thickness from 5 to 15 nm was evaporated on the photoresist layer as metallic mask layer. After recording and development processes, the profile of pits on the glass master disc was measured by atomic force microscope (AFM) to evaluate the experimental results. According to the simulation and experimental results, the pit width on the photoresist layer could be shrunk by more than 40% of the diffraction limit of the laser beam recorder.