利用奈米壓印技術製作可撓曲相位光罩以及光學波板

Abstract

由於奈米壓印微影具有高解析度、高產率、成本低廉，以及可以輕鬆的製作出奈米等級結構的優勢，因此被視為下一世代最有可能發展的微影技術。本篇論文的研究是改良傳統奈米壓印技術，將傳統的壓印硬質基板改成可塑性的高分子材料，在模板沒有脫模劑的情況下，利用冰水當作熱傳導介質，可以讓模板和基材的之間的沾黏情況大幅改善。由於基材是高分子材料，所以可以直接將模板圖型轉至基材上，製作出可撓曲的光學繞射元件--相位光罩以及單面、雙面圖型的次波長光柵的光學波板。 運用改良的奈米壓印製程製作出的光學波板，特點除了製程快速、成本低廉，我們還可以將製作的不同相位延遲量波板，串聯起來後得到各種不同相位延遲量的波板。 製作可撓曲相位光罩，週期為2μm，在最佳製程參數條件下，我們得到約3％的零階光強度。在應用上，利用相位光罩產生光阻圖型在也具可撓曲的基材上可以得到兩種實驗結果:1.若將相位光罩平放在彎曲的基材上，可以得到週期漸變的光柵圖型。2.若光罩和基材同時彎曲，進行分次曝光則在彎曲的曲面上得到相同線寬、相同週期的光柵圖型。

Nanoimprint lithography (NIL) is one of the most promising candidates for the next generation due to the advantages of high resolution, high throughput, low cost, and the ease of fabricating nanoscale patterns. In this thesis, we directly imprinted sub-micrometer patterns on plastic substrates. For the master mold without release layer, we used ice water as a heat conductor to solve the adhesion problem between the master mold and substrate. With directly imprinting on polymer substrates, we can transfer the pattern of master mold to the substrate directly and fabricate flexible optical diffraction devices, such as phase mask, and sub-wavelength optical wave plates with single- or dual-side grating patterns. Optical wave plates fabricated by nanoimprint lithography on flexible substrates have advantages of rapid process and low-cost. Besides, we can combine wave plates with different phase retardation together to obtain various phase retardation of wave plates. The period of the flexible phase mask is 2μm. With the optimal process parameters, we obtain 3% zero-order intensity of phase mask. Applications of phase mask on producing patterns on photo-resist on flexible PET substrates are also discussed. We observe two experimental results: First, a pattern of gradually changing period is obtained when the flat phase mask is putting on the bent PET substrate. Second, we obtain a pattern featuring the same line-width and period with the master mold by alternate exposure process when the phase mask and PET substrate are simultaneously bent.