利用干涉微影與奈米壓印技術製作寬頻抗反射次波長結構於平面與曲面基材上

Abstract

在許多理論與實驗的文獻中，二維次波長週期性結構已經被證實有寬頻抗反射效果，目的在增進光的穿透效率。預期在未來的太陽能電池、手機等光電產業將大量被使用，甚至取代原有鍍膜抗反射技術，因此本論文將探討抗反射結構的設計與製作。 爲了控制抗反射的頻寬以及效率,我們使用嚴格耦合波動理論精確計算出週期性結構的週期、深度、以及形狀，由模擬結果可知深寬比越高，則越有抗反射效果。 爲製作抗反射結構，我們使用雙光束干涉微影曝光，將抗反射圖案製作於矽晶圓表面，並利用電漿蝕刻技術(ICP)，製作高深寬比抗反射周期結構於矽晶圓上。 同時我們利用奈米壓印技術，把抗反射結構複製於曲面基材上。此製程優點可以大量複製，降低成本。 另外在干涉微影方面，傳統平面分光鏡會產生鬼影(ghost image)進而影響曝光圖案品質。因此，我們利用光學薄膜電磁波理論，設計了特製薄膜分光鏡(pellicle beamsplitter)，入射角可調在40與50度附近，理論上相當符合干涉微影實驗製程上的需求，我們並嘗試使用薄膜分光鏡作為製程上的改良。

In many theoretical and experimental studies, it has been proved that 2D subwavelength periodic structure contributes to the effect of broadband antireflection, in order to increase the light transmittance. We anticipated that this kind of structure will be widely used in solar cells, cell phone, etc. Even it could replace the traditional antireflection thin film coating. In this thesis, we will discuss the design and fabrication of the AR structure. In order to control the reflectance spectrum and efficiency, we utilized rigorous coupled wave analysis (RCWA) to calculate the period, depth, and shape of the periodic structure precisely. From the simulation results we realized that, the high-aspect-ratio structure will contribute to better AR performance. We utilize two beam interference lithography to fabricate AR structure on Si substrates. And by means of inductive couple plasma (ICP) etching, to fabricate the high aspect ratio, periodic, AR structure on into Si. By means of nanoimprint technique, we replicated the AR structure on curved substrates. This technique contributes to the results of mass production, cost reduction. In addition, traditional plate beamsplitter will results in ghost image in interference lithography degenerate the quality of exposed pattern. Therefore, according to the optical thin film theory, we designed the specific pellicle beamsplitter. The incident angle of the pellicle beamsplitter is around 40 degree and 50 degree, which will meet the expectation of our experimental process. We also tried to use it to improve our fabrication process.