- 學位論文
傳統穿透式電鏡中原子序對比影像之建立與研究
Z-Contrast Hollow Cone Imaging In Conventional TEM
摘要
電子顯微鏡的技術中，一般高分辨影像及明場像對材料內部之成份的訊息非常不敏感。對成份敏感之訊息在於高角度的散射電子。近年來的掃瞄穿透式電鏡（STEM）利用一個高角度環狀偵測器收集高角度的散射電子來成像，所得影像被稱為高角度環形暗場顯微術HAADF(high-angle annular dark field image)，是屬於原子序對比影像(Z-contrast imaging)。掃瞄穿透電鏡造價較一般電鏡高而且需要極安靜的操作環境。它的解析度很高可以到0.2個奈米以下，但是最大的缺點是雜訊太高，造成影像解釋上的困難。 由光學中的倒易原理(principle of reciprocity)，在傳統電子顯微鏡中也有辦法得到原子序對比的影像(Z-contrast image)，但是需要特別的空錐照射(hollow-cone illumination)系統，得到的影像稱為HCDF（hollow-cone dark field）影像。基本上空錐照射是連續傾斜入射電子束，如此會使得高角度的散射光都被傾斜至光軸上成像，以得到原子序對比的影像。此方法特點是影像抗雜訊的能力比較強，儀器整體價格也不像掃瞄穿透式電鏡那麼昂貴。在此論文中以現有之電鏡發展，控制電鏡成HCDF之技術，並以積體電路結構和銅在鋁合金中偏析為例子。
並列摘要
According to “The Principle of Reciprocity”, except for High-angle annular dark field image (HAADF) there is another kind of Z-contrast image, ”Hollow Cone Dark Filed (HCDF) image”. In this thesis, the technique of developing Z-contrast hollow cone dark field (HCDF) images by recording a series of high-angle centered dark field (CDF) images in JEOL 2000FXII TEM will be demonstrated. And two applications of the HCDF method, the VLSI device sample and the Al-Cu alloy sample, will be given. And the well known Z-contrast STEM-HAADF images were also taken for comparison with the HCDF images. The results show that the diffraction contrast can not be eliminated entirely in both HCDF and HADF images. Increasing the collection (cone) angle of HCDF images can effectively suppress the influences of the diffraction contrast. Also the HAADF image with a larger collection range suffers less influence of the strain field on intensities than the HCDF image. The HAADF imaging is higher Z-dependent and sharper in edges than HCDF imaging. However, HCDF imaging still performs satisfied results for medium resolution applications.