利用電子束直寫奈米尺度的圖案化金屬銅

Direct-Writing Cu Nano-Pattern with Electron Beam

賴世恩(Shih-En Lai)

指導教授 ： 游萃蓉

國立清華大學/工學院/材料科學工程學系/碩士(2015年)

摘要

本研究利用電子束，由硫酸銅水溶液薄膜中直寫出奈米尺度圖案化金屬銅 (Cu pattern)，反應式為: Cu2+ + 2e- → Cu，並直接沉積於基板表面。
本研究使用穿透式電子顯微鏡 (transmission electron microscopy, TEM) 做為電子束來源，型號為JEOL JEM-2010，TEM不僅能提供高聚焦且易操控的電子束來還原銅離子，並且能於直寫的過程中進行高解析度的臨場觀測。此外，硫酸銅水溶液薄膜則有助於圖案化金屬銅的生成，且能限制其還原於基板表面，而非漂浮於水溶液中。為了上述目的，本研究使用一專為TEM設計之溶液載具K-kit，K-kit能將溶液封存於其中，並於TEM的高真空環境裡進行觀測。硫酸銅水溶液以薄膜的形式，舖附在K-kit的上下兩層氮化矽薄膜上。如此一來，便可在TEM裡，以預先設計的路徑連續地移動電子束，來還原出圖案化的金屬銅。
為了直寫出連續且均勻的金屬銅圖形，本研究探討K-kit間隙 (即上下兩層氮化矽薄膜之距離)、電子束照射時間、及硫酸銅水溶液濃度對於本反應的影響，並於其中尋找最佳參數進行圖案化金屬銅的直寫。在K-kit間隙的部分，實驗中發現間隙會影響水溶液薄膜的厚度，而2 um間隙的K-kit能生成適當的水溶液薄膜厚度，幫助此直寫反應的進行。在電子束照射時間的探討，隨著電子束照射的時間越長，所還原的金屬銅將越厚。硫酸銅水溶液濃度太低會使得直寫的直線不連續，僅在電子束移動的路徑上留下銅奈米粒子，濃度太高，則很容易造成非預期的銅奈米粒子析出。
最後，本研究利用上述各個最佳化參數，來進行奈米尺度圖案化金屬銅的直寫，並成功直寫出所設計的圖形，驗證此方法之可行性。期望未來經過更仔細的研究與開發，能將此方法應用於工業界上，為奈米尺度圖案化金屬的製作提供嶄新的一頁。

關鍵字

電子束 ； 直寫 ； 圖案化金屬銅

並列摘要

The electron beam (e-beam) was utilized to direct-writing nano-scale Cu patterns on a surface with a thin aqueous layer of CuSO4 solution, through the reaction of Cu2+ + 2e- → Cu.
A transmission electron microscopy (TEM, model: JEOL JEM 2010) served as the e-beam source. The TEM not only provided highly convergent and controllable e-beam but also in-situ and high-resolution imaging after writing process. Thin aqueous layer facilitated the formation of Cu patterns and helped to confine the writing on the surface. For this demonstration, liquid sample holder (K-kit) for TEM was employed to form a sealed space in a TEM. The aqueous CuSO4 solution inside the sample holder was allowed to partially dry-off until a thin aqueous layer was left on the surface. E-beam was thus manipulated with pre-designed path to reduce the Cu ion in the solution and form the desired patterns.
The influence of gap of K-kit (the spacing between upper and lower Si3N4 film), e-beam exposure time, and concentration of CuSO4(aq) was studied to find the optimized condition for direct-writing of Cu patterns. It was found that the gap of K-kit would impact the thickness of CuSO4(aq) solution thin film, and K-kit with 2 um gap could create a suitable thickness to facilitate the reaction. When it comes to the influence of e-beam exposure time, it was found that the thickness of reduced Cu increased with the increase of exposure time. At an insufficient CuSO4(aq) concentration, the Cu patterns would become discontinuous and only Cu nanoparticles were left on the e-beam moving path. On the other hand, Cu nanoparticles would freely nucleate near Cu patterns at an excessive CuSO4(aq) concentration.
Finally, an optimized condition was used for nano-scale Cu patterns direct-writing successfully. This method shows significant potential for the application on patterned metal fabrication and worth further detailed study and development.

並列關鍵字

electron beam ； direct-writing ； Cu nano pattern

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