以選擇性磊晶成長方式即時製備高溫超導薄膜元件之研究

Abstract

本研究以選擇性磊晶成長法於鈦圖案化基板上即時製備釔鋇銅氧薄膜元件。使用電子束蒸鍍系統在鈦酸鍶基板上鍍上鈦金屬薄層，運用剝脫技術將之圖案化，以作為成長釔鋇銅氧高溫超導薄膜之模板。研究結果顯示，鈦薄層先行氧化，而成長於其上之釔鋇銅氧薄膜形成結構鬆散之絕緣層；直接成長於鈦酸鍶基板上之釔鋇銅氧薄膜，則形成性質及結構十分優異之超導相；二區域交界處界線分明陡直。以選擇性磊晶成長方式製備微橋結構及量子干涉結構之元件時，元件在鍍膜的過程中即時長成，且超導特性良好並未有任何劣化的趨勢。避免以往製程迫使元件接觸酸液和有機溶劑，以及蝕刻步驟中對元件結構和超導特性的損害。此研究之結果對往後製作次微米尺寸之高溫超導薄膜元件有正面之助益。

A novel process, highly compatible to the current semiconductor technologies, is developed to fabricate high-Tc superconducting(HTS) devices in-situ. YBa2Cu3O7-d(YBCO) films deposited on substrates masked by thin Ti layers exhibits excellent selective epitaxial characteristics. The YBCO grown directly on unmasked areas of SrTiO3 substrates showed undegraded superconductivity, while that grown upon Ti masked areas became insulating. By combining this "selective epitaxial growth (SEG)" process with the commonly used lift-off technique, a patterned SQUID with a pick-up coil device structure was successfully demonstrated. The results show that the devices have well-defined edges and drastically different appearances in surface morphology between different areas. It is anticipated that the current process can have extremely high potential in obtaining devices with very fine feature sizes and complex structures in-situ without encountering the fatal damages in the superconducting films frequently suffered from etching and photolithographical process.