磁性穿隧元件之異質結構調整與研究

Study and Engineering of Heterostructure for Magnetic Tunnel Junction

李永誠(Yung-Cheng Li)

指導教授 ： 白奇峰

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2022年)

https://doi.org/10.6342/NTU202201531

摘要

隨著摩爾定律即將走至盡頭，次世代記憶體在近年因此受到越來越多的關注。磁阻式隨機存取記憶體因其非揮發性、低能耗與高度整合性使其成為備受期待的角逐者之一，而相較於其他種類的磁性記憶體，自旋軌道扭矩磁阻式隨機存取記憶體擁有高速寫入、高耐久度、低寫入電流等優勢而相當被看好。在本系列實驗中我們首先以自旋軌道扭矩磁阻式隨機存取記憶體的架構製作對於磁性記憶體而言最重要的構造—磁性穿隧結，並量測其穿隧式磁阻及在不同磁性穿隧結面積與氧化鎂厚度下自旋轉移扭矩與電壓控制磁各向異性等帶來的效應。之後為了發展垂直異向性磁性穿隧結，我們先利用以鉑鈷多層膜剝離成形製作的元件並藉由異常霍爾效應的曲線偏移與電流翻轉等方法測量其基本電性，接著以其薄膜樣
品製成磁性穿隧結並探討在薄膜成積或樣品製作導致其失敗的因素，期望能提供一點啟發及相關資訊給其他致力於磁性穿隧結研究的人。

關鍵字

自旋軌道矩式記憶體 ； 磁性穿隧結 ； 鉑鈷多層膜 ； 自旋軌道矩 ； 自旋霍爾效應

並列摘要

As the end of Moore’s law approaches, next generation memories receive more and
more attention in recent years. Nonvolatility, low power consumption, and high integrability make Magnetoresistive Random Access Memory (MRAM) one of the promising candidates. Among different categories, spin-orbit torque MRAM (SOT-MRAM) is contemporarily the most prospective species under limelight, which contains the advantages including high speed writing, high endurance, and low writing current. In this series of experiments, we first fabricated magnetic tunnel junctions (MTJs), the most critical component in MRAM, based on the configuration of SOT-MRAM, and measured tunneling magnetoresistance (TMR) with the effect from spin-transfer torque (STT) and voltage control magnetic anisotropy (VCMA) in different sizes of pillar and thickness of MgO.
To further develop perpendicular magnetic anisotropy (PMA) MTJs, we prepared lift-off samples made of PtCo multilayers, and characterized their transport properties through current switching and anomalous Hall effect (AHE) loop shift measurement; we then made thin films composed of PtCo multilayers into MTJs and evaluated the possible reasons causing failure during fabrication process or deposition, in hope of inspiring others who strives for MTJ research with essential information.

並列關鍵字

SOT MRAM ； magnetic tunnel junction ； PtCo multilayers ； spin-orbit torque ； spin Hall effect

參考文獻

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