臺灣博碩士論文加值系統

本研究利用掃描探針顯微鏡(Scanning probe microscopy)之微影蝕刻技術(Lithography)，用以製作約瑟夫森穿隧元件之弱連接處，並且改變製作時探針偏壓大小與掃描速率以研究其特性變化。實驗中使用離軸式射頻磁控濺鍍(RF magnetron sputtering)系統，以SrTiO3 (100)為成長基材，成長薄膜厚度150 nm之高品質釔鋇銅氧超導薄膜，再利用X-ray晶格繞射儀(XRD)與原子力顯微鏡(AFM)做薄膜特性量測。而圖形製作方面，則是利用光學微影技術(Photolithography technology)與離子蝕刻技術(Ion etching)製作出3 μm微橋圖形。
當我們施加偏壓超過一個臨界值時，薄膜表面將會成長出奈米級氧化線，而依照陽極氧化作用原理，隨著掃描速度的改變，所生成的氧化物寬度與高度也會有所變化。在電阻對溫度特性曲線量測結果發現，在接近超導態時有因弱連結引起正常態/超導態之展緩變化行為，顯示此技術對於未來製作超導量子干涉元件(SQUID)有更進一步成功的可能。

Superconducting quantum interference devices (SQUIDs) were fabricated by inducing a selective surface modification on YBa2Cu3O7-y (YBCO) microbridges with an atomic force microscope lithography (AFML) attached in a scanning probe microscopy (SPM) system. The surface modification was probated in the electric field of conductive AFM tip and created oxide protrusions across the entire strips as the tunneling barriers High-Tc superconducting YBCO thin films were grown on SrTiO3 (STO) substrates by using rf magnetron sputtering. The photolithography and ion etching techniques were used to fabricate the thin film for SQUID pattern with 3-μm-width mircobridges. The crystalline orientation and the surface morphology were characterized by the X-ray diffraction (XRD) and the AFM, respectively.
The surface modification can be controlled by tuning the applied bias voltage and scan speed with threshold values of 5 V and 0.1 μm/sec. The protrusion height is increased with an increase of bias voltage or a decrease of scan speed. The temperature dependent of resistance for the fabricated SQUID reveals a resistive broadening as temperatures near Tc, showing a superconducting-tunneling-like behavior.

封面內頁
簽名頁
授權書．．．．．．．．．．．．．．．．．．．．．．iii
中文摘要．．．．．．．．．．．．．．．．．．．．．iv
英文摘要．．．．．．．．．．．．．．．．．．．．．．v
誌謝．．．．．．．．．．．．．．．．．．．．．．．vi
目錄．．．．．．．．．．．．．．．．．．．．．．．vii
圖目錄．．．．．．．．．．．．．．．．．．．．．．．ix
表目錄．．．．．．．．．．．．．．．．．．．．．．xiii

第一章 緒論
1.1 研究背景 ．．．．．．．．．．．．．．．．．．．．1
1.2 研究動機．．．．．．．．．．．．．．．．．．．．6
第二章 簡介與基礎原理
2.1 超導體的起源與發展．．．．．．．．．．．．．．．8
2.2 超導體的特性．．．．．．．．．．．．．．．．．．9
2.2.1 臨界溫度 ．．．．．．．．．．．．．．．．．9
2.2.2 零電阻 ．．．．．．．．．．．．．．．．．．9
2.2.3 抗磁性 ．．．．．．．．．．．．．．．．．．9
2.3 約瑟夫森接面．．．．．．．．．．．．．．．．．．11
2.3.1 直流約瑟夫森效應 ．．．．．．．．．．．．．11
2.3.2 交流約瑟夫森效應 ．．．．．．．．．．．．．16
2.4 掃描探針式顯微鏡概況與原理．．．．．．．．．．．22
2.4.1 掃描探針式顯微鏡演進 ．．．．．．．．．．．22
2.4.2 原子力顯微鏡原理 ．．．．．．．．．．．．．23
2.4.3 原子力微影蝕刻技術．．．．．．．．．．．． 25
第三章 樣品製作與量測系統
3.1 成長基板選取．．．．．．．．．．．．．．．．．．28
3.2 釔鋇銅氧薄膜之成長與特性．．．．．．．．．．．．30
3.3 光學微影製程．．．．．．．．．．．．．．．．．．35
3.4 樣品蝕刻製程與電極接腳製作．．．．．．．．．．．37
3.5 掃描探針顯微鏡微影蝕刻製程．．．．．．．．．．．40
3.6 特性量測系統．．．．．．．．．．．．．．．．．．46
第四章 實驗結果與討論
4.1 釔鋇銅氧薄膜氧化作用特性分析．．．．．．．．．．48
4.2 微橋氧化作用分析．．．．．．．．．．．．．．．．56
4.2.1微橋表面氧化線宽度分析．．．．．．．．．．． 56
4.2.2微橋薄膜深度氧化破壞分析．．．．．．．．．． 65
第五章 結論 ．．．．．．．．．．．．．．．．．．．．．．75
參考文獻 ．．．．．．．．．．．．．．．．．．．．．．77

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