在以往以矽或玻璃為基材之金屬壓印中，發現基材效應造成成型力量變大，模具容易損壞，因此本論文利用硬薄膜/軟基材之構想，使用PMMA為基材，取代之前軟薄膜/硬基材系統，對鋁薄膜進行壓印實驗。藉由奈米壓痕實驗比較矽與PMMA基材對鋁薄膜機械性質之影響，而後壓印實驗以成型高度做為判斷鋁薄膜成型品質之依據，進一步對照壓痕結果，了解不同基材效應影響下鋁薄膜機械性質與成型高度之間的關係，並利用FIB與SEM分析壓痕截面，了解軟硬基材之基材效應對薄膜塑性變形影響之機制。
由各項實驗結果可以得到以下結論:鋁薄膜在矽基材上，因塑性變形只發生在鋁薄膜內，薄膜內差排堆積嚴重，硬度值隨壓深增加而升高，且有pile-up現象；在PMMA基材上，因為PMMA先產生降伏，所以硬度隨壓深增加而降低，且有sink-in現象。壓印結果發現，鋁薄膜在PMMA基材上成型高度的確比在矽基材上高出許多，兩種基材之薄膜在填充模穴後的表面形貌也符合鋁薄膜/PMMA基材填充率較高的結果，並可以了解鋁薄膜/PMMA基材之塑性成型由基材主導，此結果也可解釋PMMA填充進模穴造成鋁薄膜劇烈彎曲破裂；鋁薄膜破裂形成的bi-layer結構，雖與原本設計不同，但仍具有光學性質的潛力；利用EDS分析顯示此製程中模具沾黏薄膜材料或是PMMA基材的行為可以忽略。

This thesis is focused on the influence of properties of substrate on formability of direct nanoimprint technique. Using silicon or glass material as the substrate for the direct metal imprint, it is found that higher imprinting force and fracture of mold may occur. Consequently, the formation of hard film/soft substrate system like Al/PMMA in replace of the soft film/hard substrate system is studied herein. The mechanical properties of aluminum thin film on different substrates are characterized by nanoindentation experiments. Subsequently, formation height will be applied to analyze the formation qualities in the nanoimprint process. It can be compared with results of nanoindentation, the relationship between mechanical properties of aluminum thin films on different substrate effects and formation height will be comprehended. In addition, formation mechanism will be understood via observing the cross-section of the microstructures of thin films after imprint process by using FIB and SEM.
Based on the indentation results, the following phenomena can be observed. In the case of Al on silicon, the plastic deformation is contained within the film and this system exhibits strain gradient effects and pile-up phenomenon occurs. On the other hand, in the case of Al on PMMA, the hardness decreases with increase of the depth of indentation because that PMMA substrate starts yielding. Al/PMMA system exhibits sink-in phenomenon. Analyzing the imprint results, the formation height on Al/PMMA system is better than Al/Si system and formation ratio can be used to estimate the surface topology of deformed thin films. Surface topology of deformed Al/PMMA is single peak and the case of Al/Si is dual peak, this result conformed that deformed thin films should be single peak when the formation quality is good. Subsequently, formation mechanism of Al/PMMA system was led by plastic deformation of PMMA substrate, this result can be used to explain that Al thin film was bent, fractured and stretched by the behavior of PMMA filling into cavity of mold. This bi-layer structure still possesses potential optical properties even though the nanostructure is different from original design. According to the EDS results, there is neither aluminum composition nor PMMA being found on the silicon molds and the adhesion behavior between molds and thin films could be negligible.

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