本研究利用紫外光固化之奈米壓印製程技術搭配可撓式模具，應用於圖案化藍寶石基板 (Pattern Sapphire Substrate, PSS) 的量產製程。實驗中根據可撓式模具的柔軟特性，能夠完美地貼附於具一定翹曲的藍寶石基板上，可改善傳統硬質壓印模具成本高及良率低的問題，藉由軟接觸的方式增加奈米壓印製程的良率，提升壓印製程在大面積的可行性。另外，紫外光固化之壓印製程有著製程快速及常溫操作的優點，因此非常適合應用於量產的製程。本文成功的在四吋藍寶石基板上製作出柱狀及金字塔型貌的光阻結構，作為後續對藍寶石基板進行乾式蝕刻時的蝕刻遮罩，最後完成圖案化藍寶石基板的製作。
柱狀結構製程是以傳統的矽基硬質模仁作為母模，翻製出高透光性的PDMS模具，並以此模具執行壓印製程；目前本文成功壓印出與業界相同線寬2 um、週期3 um的特徵尺寸，並提升壓印高度至3.5 um、殘餘層僅為35 nm的光阻結構蝕刻遮罩，並經由乾式蝕刻可得到底寬2.57 um、高度1.43 um錐狀形貌的圖案化藍寶石基板。三維金字塔製程的矽母模乃利用矽體加工製程所得到，並翻製出h-PDMS作為壓印模具，並在藍寶石基板上壓印出線寬2 um、週期3 um、高度1.15 um、殘餘層70 nm的結構，並在蝕刻後於藍寶石基板表面得到線寬1.26 um、高度638 nm的金字塔微結構。形貌為金字塔狀的圖案化藍寶石基板較其他種類的形貌更能提升發光效率；另外，因為金字塔形貌的光阻遮罩在乾式蝕刻製程中不需加入修飾遮罩形狀的程序，因此能減少蝕刻時間，獲得較好的產能，此為金字塔型貌遮罩的特點。

In this thesis, flexible molds and ultraviolet (UV) nanoimprint lithography are applied for fabricating pattern sapphire substrates (PSSs). Due to the deformable and flexible characteristic of the soft stamps, it is possible to achieve a conformable contact with sapphire substrates, which typically have certain degree of non-flatness such as warp and bow. Using flexible molds can significantly improve the yield of imprinting processes and reduce the cost. On the other hand, UV nanoimprint has the advantages of large patterning area, high throughput, and room operating temperature, which make it highly suitable for mass production. In this works, arrays of pillar and pyramid micro-structures are successfully imprinted on a layer of photoresist (PR), which acts as the etching mask for subsequently ICP dry etching process on 4-inch sapphire substrates to fabricate pattern sapphire substrates.
In fabricating hexagonally arrayed pillar-shaped PR micro-structures, PDMS imprint stamps which are duplicated from a hard silicon mold are used. To meet the specifications of LED industry, the diameter and center-to-center pitch of these pillar arrays is 2 um and 3 um, respectively. The imprinted height and the residual layer thickness are 3.5 um and 35 nm, respectively. After dry etching, cone-shaped surface micro-structures with a base diameter of 2.57 um and a height of 1.43 um are obtained.
For three dimensional pyramid micro-structures, a silicon mold is first prepared by standard photolithography and silicon bulk machining. An h-PDMS stamp is replicated and employed to fabricate three-dimensional pyramid PR micro-structures which are 2 um in base length, 3 um in center-to-center pitch, 1.15 um in height, and 70 nm in residual thickness. After dry etching process, the obtained pyramidal sapphire surface micro-structures are 1.26 um in base length and 638 nm in height. The pyramidal pattern sapphire substrates can have higher luminance efficiency due to stronger light scattering effect. Besides, the time needed for dry etching process for pyramidal surface profiles can be reduced because there is no need to first modify the pillar-shaped PR microstructures. This is the advantage of using UV nanoimprint lithography to fabricate three dimensional pyramidal PR micro-structures as the dry etching mask in mass-production of pattern sapphire substrates.

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