Fabrication of a New Square Periodic Structure by Two-beam Interference Technique

• Main Authors: Yu-Di Huang, 黃郁迪
• Other Authors: 許佳振
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/22371080392776718658

碩士 === 國立中正大學 === 物理所 === 97 === In this thesis, we fabricate a new square periodic structure by two different methods, which is constituted by square rods connecting with narrow veins. In order to fabricate the narrow veins, we demonstrate two methods to decrease the concentration of photo-initiator. The first method: Mix another photo-initiator with the resists and then change the excitation wavelength. The second method: Dilute the photoresist with the other resists. We have demonstrated the narrow veins can be fabricated in SU-8 with resolution as high as 50 nm. This result surpasses similar results reported to date, and approaches the intrinsic resolution limit of SU-8 (a few nanometres) defined by the monomer dimensions. The obtained new square structure is constituted by square rods connecting with narrow veins and its pattern is different to the result of theoretical prediction based on interference intensity distribution. The difference is attributed to the diffusion of photoacid during the photopolymerization process. This new square structure is proved theoretically to open a complete photonic bandgap at high refractive index contrast. The periodic SU-8 structures can be considered as photonic crystal templates for transferring into other higher refractive index materials.