薄膜性質對於金屬奈米壓印成型之影響

Effects of Thin Film Properties on Metallic Pattern Formation by means of Direct Nanoimprint

吳建利(Chien-Li Wu)

指導教授 ： 宋震國

國立清華大學/工學院/動力機械工程學系/碩士(2007年)

摘要

本論文主要研究金屬薄膜性質，包括晶粒大小與微結構缺陷，對奈米壓印成型的影響。本文以鋁薄膜作為壓印成型材料，透過不同薄膜製程與製程參數的設計，有效地改變以晶粒大小為主的薄膜顯微結構。其後使用TEM與EDS分析薄膜厚度、內部缺陷與組成元素等相關資訊，並藉由奈米壓痕實驗了解薄膜之顯微結構與機械性質間的關係。隨後的奈米壓印實驗將以成型高度作為判斷鋁薄膜成型品質的依據，進一步對照薄膜機械性質與壓印成型結果之間的關係，並配合TEM進行壓印後薄膜微觀結構分析，可進一步釐清薄膜塑性變形的機制。此外為了瞭解在金屬直接奈米壓印製程中是否存在模具沾黏薄膜材料的行為，將針對壓印後模具進行EDS分析。

由各項實驗結果可以得到以下結論：鋁薄膜在離子束濺鍍過程中，適當調整其電壓可製作出非晶質或晶粒大小5~65奈米的各種薄膜；在相同膜厚下愈大的晶粒其硬度愈低，符合Hall-Petch理論，而非晶質薄膜則因為近似於氧化鋁的性質而反應出最高的硬度；大晶粒且硬度低的薄膜其壓印成型結果較佳，並可藉由填充率的計算推測薄膜壓印成型結果，填充率好的情況下薄膜成型表面將為單峰形貌，反之則為雙峰；利用高倍率TEM的分析可觀察到110奈米晶粒大小的薄膜受到塑性變形後內部存在差排，15奈米晶粒之薄膜則無，可間接證實大晶粒的薄膜以差排運動作為塑性成型機制，而小晶粒的薄膜則以晶界滑移為主；根據分析結果顯示金屬直接奈米壓印製程中模具沾黏薄膜材料行為是可以忽略的。

關鍵字

奈米壓印 ； 金屬薄膜 ； 塑性成型

並列摘要

This thesis is focused on characterizing the mechanical properties of the thin film as function of grain size, defect and fabrication process, and investigating the effect of mechanical properties on formation of direct nanoimprint technique. Aluminum thin films will be used as the transferred material and the grain size and microstructures can be controlled by means of different deposition process and parameters. In order to analyze film thickness, internal defects, and composition, TEM and EDS are employed after the thin-film deposition process. The relationship between microstructures and mechanical properties of thin films can be characterized by nanoindentation experiments. Subsequently, formation height will be applied to analyze the formation qualities in the nanoimprint process and it can be compared with the mechanical properties of thin films. In addition, formation mechanism will be understood via observing microstructures of thin films after imprint process by TEM analysis. For the purpose of analyzing the adhesion behavior between thin film materials and silicon molds, EDS will be performed to detect the composition of the mold after imprint experiments.

Base on the experimental results, the following phenomena can be observed. Aluminum thin films with amorphous crystal structure and grain size between 5 to 65 nm could be achieved by ion-beam sputter deposition using different ion-beam voltage. At the same film thickness, lower hardness is observed when the grain size increases and this phenomenon is called Hall-Petch effect. The hardness of amorphous thin film is very high because its properties are similar to aluminum oxide. When the grain size of the thin film increases, the formation height is better and formation ratio could be used to estimate the surface topology of deformed thin films. Surface topology of deformed thin films should be single peak when the formation quality is good. Otherwise, it will be dual peak. Dislocation defect could be observed in the deformed thin films with 110 nm grain size but not in the thin films with 15 nm grain size. It could be concluded indirectly that dislocation motion is the dominant plastic deformation mechanism for the thin films with large grain, whereas grain boundary sliding is the major formation mechanism for the small grain materials. According to the EDS results, there’s no aluminum composition being found on the silicon molds and the adhesion behavior between molds and thin films could be negligible.

參考文獻

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