同心圓奈米結構與表面電漿子互動之研究-奈米直寫儀與三維次波長光學頭之整合研製

Abstract

本文根據過去六年中，全世界各研究團隊對於光場的異常穿透現象與指向性之研究與應用，以及本研究團隊過去三年內對於奈米直寫儀的研究成果，提出具玻璃基材之三維次波長同心圓，而表面為週期性結構光學頭，進行點狀光源光學頭之研製，同時將此一創新技術整合應用於奈米直寫儀，嘗試能在可見光範圍曝光出接近，甚至突破傳統繞射極限的線寬。論文內容包含使用表面電漿理論解釋異常穿透現象及指向性的機制、具有玻璃基材之金屬光學頭的製程、穿透光之遠場光學行為觀察。使用有限元素法(finite element method, FEM)配合嚴格耦合波分析(rigorous coupled wave analysis, RCWA)模擬穿透光之電磁場分布情況，並介紹奈米直寫儀之架構以及系統之校準。 由實驗結果可知，具有基材之三維次波長同心圓表面週期性結構光學頭與獨立金屬薄膜(free-standing metal film)三維次波長同心圓表面週期性結構光學頭，其出射光均同樣具有指向性的效果。並且建立製程基礎。藉由模擬軟體設計，適用於奈米直寫儀光學頭，使其光學特性以及尺寸符合奈米直寫儀所需。在未來工作中，提出使用近場光學顯微鏡(NSOM)以及模擬軟體，以得知出射能量以及光點大小，以利曝光實驗的順利進行。

This thesis concentrated its focus on the directionality of the output transmission through a subwavelength annular aperture even though the directionality issue remains active considering the many papers published in the last few years. In the past three years, the NTU Nano-Bio MEMS Group has made many progresses in the Nanowriter project funned by the Material Research Laboratory, Industrial Technology Research Institute, Taiwan. The main target of this thesis is to fabricate an optical head for nanowriter system with a subwavelength annular aperture and periodic annular structure on a glass substrate. This thesis includes using surface plasma theory to explain the mechanism of directionality phenomena, fabrication process of metal films with subwavelength surface structure on a glass substrate, observation of transmission light beam in far field. Both Finite Element Method (FEM) and Rigorous Coupled Wave Analysis (RCWA) were used to simulate electromagnetic filed distribution of transmission light beam from near-field to far field. Finally, the implementation of the above-mentioned technologies of nanowriter system was detailed. The experimental results confirmed that the metal films with subwavelength surface structure on a glass substrate had directionality of output transmission as that of the pure metal film case published previously. In addition, the three-dimensional optical head fabrication processes was developed. By using simulation software and the fabrication processes, the optical head satisified the need of the nanowriter system had been designed successfully, and the output transmission was measured by using an optical microscope. Future works of this thesis are to confirm the output power and the spot size of output beam of optical head by using NSOM and simulation software and to exposure lines with width close to diffraction limit in ambient conditions.