本論文提出兩套新穎的圖形化藍寶石基板製程技術，分別為”金屬植入式黃光微影技術”和”PDMS軟性光罩微影技術”。金屬植入式黃光微影技術是一種結合"壓印/轉印技術"與"曝光微影技術"的創新製程技術，透過金屬轉印製程將PDMS模具凸起表面的金屬圖案轉移至藍寶石基板表面的光阻層上，再透過紫外光照射對未被金屬遮擋的光阻層進行曝光，經過顯影後留下金屬遮罩下方的光阻結構，完成表面光阻圖形的定義；最後將金屬遮光罩用金屬蝕刻液去除，最後留下的光阻結構即可作為後續乾式蝕刻製程所需的遮罩。此方法結合了奈米壓印製作大面積、小線寬圖形的能力，與黃光微影技術的高量產穩定特性，其特點為適合做小線寬的高深寬比光阻結構。本文中成功地利用此方法製作出線寬500 nm、結構高2500 nm的光阻結構，其深寬比達到2.5。
PDMS軟性光罩微影技術是屬於一種接觸式曝光製程，但是採用PDMS軟性光罩取代傳統的玻璃或石英硬式光罩。其特色為可以利用PDMS軟式光罩柔軟的特性去克服藍寶石基板表面的不平整，使光罩與基板完美的貼合。實驗結果顯示：本製程可輕易地在藍寶石基板上製作大面積與小線寬的光阻結構，且具有高產速與高穩定性等優點。本文中提出兩種不同的軟性光罩製作方式，第一種為金屬鑲入式PDMS軟性光罩，其製作方式為使用金屬蒸鍍機在PDMS模具表面鍍上一金屬遮光層，然後利用金屬轉印製程將在模具凸出表面的金屬移除，留下內凹結構內的金屬，作為後續曝光製程所需的遮罩。本製程開發的時間較久，且其製程較為穩定成熟，目前已開始進行自動化量產機台的小批量生產測試。第二種為黑光阻遮罩PDMS軟性光罩，此方法的特色為使用旋轉塗佈的方法，塗佈黑光阻遮光層來取代金屬蒸鍍製程；塗佈在PDSM模具表面的黑光阻經過加熱烘烤後會自動縮入模穴的凹槽中，最後利用轉印製程將殘留在上表面的黑光阻移除，即完成黑光阻遮罩PDMS軟性光罩的製作。此方法最大的好處為大幅度地簡化了製程並且降低製程的成本，在未來大量生產中具有極高的潛力。
圖形化藍寶石基板在高亮度發光二極體產業中有極大的用處，未來發光二極體的產業趨勢將會漸漸地往4吋與6吋基板發展，然而受限於藍寶石基板本身翹曲的問題，目前業界所廣泛使用的投射式曝光設備無法有效率地製作4吋與6吋圖形化藍寶石基板，亦無法製作出次微米或奈米等級的圖案化藍寶石基板；且二手投射式曝光設備的維修與保養費用也逐年升高，目前急需一種新的製程與設備來填補未來圖案化藍寶石基板的生產需求。本文中提出的金屬鑲入式PDMS軟性光罩微影技術，具有在不平整的藍寶石基板上快速且大面積製作次微米等級光阻結構的能力，目前已針對此製程技術與合作廠商共同開發專用自動化設備(SPL2400)，此設備為2吋與4吋共用設備，具有全自動生產能力，且4吋圖形化藍寶石基板的產能高達70片/小時。此一自動化設備已於新竹的”隆達電子”進行量產測試，進行了包含均勻度檢測、缺陷數檢測、與LED磊晶測試...等測試，目前可以穩定生產4吋圖形化藍寶石基板，其缺陷數量約在300個，且結構均勻度符合業界標準，也成功完成LED的磊晶與點亮測試。本文證明PDMS軟性光罩微影技術具有非常好的量產能力，在未來4吋、6吋、與次微米或奈米等級圖案化藍寶石基板的量產製程上具有非常高的潛力。

This dissertation has successfully demonstrated two different types of soft lithography techniques to fabrication pattern sapphire substrate (PSS), namely “metal embedded lithography” and “soft photo-mask contact lithography”. The metal embedded lithography is a novel nano/micro fabrication process combining nano-imprinting and photolithography. This method uses a metal transfer process to transfer the metal pattern defined by a soft mold to a PR layer deposited on a sapphire substrate surface. The transferred metal pattern will then act as a photo-mask for subsequent UV exposure. After development process, the PR microstructure is defined on the sapphire surface. This process inherits the advantages from metal contact transfer and photolithography, such as large patterning area, small line width, high throughput, and high aspect ratio.
The second proposed method is “soft photo-mask contact lithography”, which is based on traditional contact type photolithography process but using a soft photo-mask to replace the hard glass/quartz photo-mask. This soft photo-mask can overcome the non-flat surface problem of sapphire wafers and make a perfect contact with them for subsequent UV-light exposure. This process is especially suitable for PSS mass production since it can easily fabricate large-area pattern on non-flat sapphire wafers with high thought put and high reliability. Two different photo-masks have been proposed for their applications in soft photo-mask contact lithography, namely “PDMS/metal-film photo-mask” and “carbon-black/PDMS soft mask”. The PDMS/metal-film photo-mask is by using a metal evaporator system to deposit a metal film on a soft mold, and then removing part of the metal layer. The metal pattern defined by the mold's concave surface form a soft photo-mask. This process is becoming mature and stable, and ready for mass production test. The second type mask is the carbon-black/PDMS soft-mask. It is by using a carbon black PR to act as an opaque layer. The preparation of this carbon-black/PDMS soft-mask is based on spin-coating and contact transfer techniques, and has significantly simplified the fabrication process and reduced the cost.
In reviewing the progress of LED industry, 4” and 6” PSSs and sub-micrometer /nanometer scaled PSSs (NPSSs) are excepted to become the dominant products in the near future. However, projection type photolithography used in LED industry is not able to meet the challenges. In this dissertation, an automatically equipment based on the proposed soft photo-mask lithography is commercially built by a local equipment company, and is tested for mass production of 4" PSSs in a local epitaxy company. The test results show that there are still certain issues to be answered such as defect counts and lifetime of the soft photo-mask. However, outstanding performance on throughput, production stability, microstructures' homogeneousness, and large wafer size, ...etc. have shown great potential of this soft photo-mask contact lithography for the industrial mass production of 4” and 6” PSSs and NPSSs in the near future.

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