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研究生:許智程
研究生(外文):Chih-cheng Hsu
論文名稱:不同絕緣層的垂直式磁性穿遂介面之製備與量測研究
論文名稱(外文):Fabrication and Analyses of Perpendicular Magnetic Tunneling Junction with Different Barriers
指導教授:吳德和
指導教授(外文):Te-ho Wu
學位類別:碩士
校院名稱:國立雲林科技大學
系所名稱:光學電子工程研究所
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2006
畢業學年度:94
語文別:中文
論文頁數:74
中文關鍵詞:磁阻式隨機存取記憶體磁滯曲線垂直式磁性穿遂介面電流平行膜面穿遂法
外文關鍵詞:CIPThystersis loopMRAMpMTJ
相關次數:
  • 被引用被引用:2
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本論文主要分成三部分。第一部份為不同絕緣層的垂直式磁性穿遂介面(pMTJ)的製備,實驗結果發現以氮化矽(SiNx)為穿遂絕緣層的pMTJ結構中,有著較低的飽和磁化量(Ms)。第二部分則為使用導電式原子力顯微鏡量測鑄型化元件的討論,並使用下壓探針的方法,可以得到更穩定的電壓電流訊號(I-V curve)。最後是設計一套實驗步驟適用於電流平行膜面穿遂法(CIPT)量測磁阻,經過理論的推導計算,可以量測出未鑄型化TMR結構的磁阻(MR)與磁阻變化率(MR ratio)。
首先在製備不同絕緣層的垂直式磁性穿遂介面(pMTJ)研究上,本論文使用直流與射頻磁控式濺鍍系統所製備,並選用氧化鎂(MgO)、氧化鋁(AlOx)與氮化矽(SiNx)三種不同的穿遂絕緣層,結果顯示以SiNx為穿遂絕緣層的pMTJ結構,其磁性自由層(free layer)有著比MgO和AlOx來的更低的飽和磁化量(Ms),較低的飽和磁化量對於未來使用自旋傳輸(Spin transfer torque)當讀寫技術上,能得到較低的翻轉臨界電流,相對地就可以降低耗電量。
而在使用導電式原子力顯微鏡(Conducting AFM)量測鑄型化元件研究上,經過實驗後,檢測出Conducting AFM的量測極限,並且使用下壓探針法來避免樣品表面原生氧化物的影響,使得能夠量取更穩定且較精準的非線性電壓電流曲線(non-linear I-V curve)。
最後,設計了一套簡單的實驗步驟,並設計出兩道光罩,使得未鑄型化TMR結構的樣品在需兩道光微影與乾式離子蝕刻術製程之後,即可實現CIPT法量測未鑄型化TMR結構的MR與MR ratio(%)。
The purpose of this thesis is to demonstrate that the tunneling barrier plays an important role for Magnetic Random Access Memory (MRAM) devices. In according to this purpose, this thesis is containing three parts including the fabrication of perpendicular Magnetic Tunneling Junctions (pMTJs) with different barrier layers, the electrical analysis of patterned pMTJ structures by Conducting Atomic Force Microscopy (CAFM), and the design of Current in-plan Tunneling (CIPT) method for measuring the magnetoresistance (MR) on unpatterned pMTJ samples. The pMTJ structures were fabricated by dc and rf magnetron sputtering. The general stacking of pMTJ samples was Si / Pt (20) / TbFeCo (35) / FeCo(2) / barrier (2) / FeCo (2) / GdFeCo (50) / Pt (20) (thickness in nm), where the GdFeCo layer acted as free layer and TbFeCo acted as pinning layer and the tunneling barrier included AlOx, MgO and SiNx layers. The interface among each deposited layer presented a smooth and homogeneous roughness. The magnetic characteristics of pMTJ structures, obtained by Alternating Gradient Magnetometer (AGM), showed lower saturation magnetization (Ms) and higher coercivity (Hc) values for pMTJ containing SiNx barrier layers than those containing the other tunneling barriers. With reduction of Ms value could be possible to get low current values useful for MRAM devices. The conducting AFM could simultaneously provide quite clear topographical and electrical images on patterned pMTJs array of ellipses of several sizes in micrometer scale. A method of piercing the top layer, for avoiding the patterned pMTJ surface oxidation, was used for obtaining stable current-voltage (I-V) curves. Finally, the design of CIPT method for measuring MR via simple photolithography and reactive ion etch have already been finished although the experimental measurements still are necessaries, which are out of reach of this thesis work.
中文摘要 i
英文摘要 ii
誌 謝 iii
圖目錄 vi
一、緒論 1
1.1 簡介 1
1.2 動機 1
二、文獻回顧 3
2.1 磁阻種類與發展背景 3
2.2 穿遂磁組的穿遂行為機制與Simmon’s equation 7
2.3 不同穿遂絕緣層的磁性穿遂介面(MTJ) 8
2.4 垂直式磁性穿遂介面(pMTJ) 12
2.5 磁阻式隨機存取記憶體與其他記憶體介紹 13
2.6 自旋轉移磁矩機制(Spin transfer torque) 15
三、實驗設備與分析儀器 17
3.1 射頻與直流磁控反應式濺鍍系統 17
3.1.1. 原理 17
3.1.2. 六靶式高真空射頻與直流磁控反應式濺鍍系統 17
3.2 交替梯度磁測儀 18
3.3 掃描式電子束顯微鏡與乾式離子蝕刻機 19
3.3.1 掃描式電子束顯微鏡 (SEM) 19
3.3.2 乾式離子蝕刻機 20
3.4 導電式原子力顯微鏡與磁性原子力顯微鏡 20
3.4.1. 簡介 20
3.4.2. 操作原理 21
3.4.3. 導電式原子力顯微鏡 21
3.4.4. 磁性原子力顯微鏡 22
3.5 光罩對準機 23
3.6 反應式離子蝕刻機 23
3.7 四點探針量測儀 24
3.8 穿透式電子顯微鏡 25
3.9 熱蒸鍍系統 26
四、實驗結果與討論 28
4.1 簡介 28
4.2 使用射頻與直流磁控反應式濺鍍系統製備垂直式磁性穿遂介面 28
4.3 不同絕緣層的垂直式磁性穿遂介面結構與磁滯曲線分析比較 29
4.3.1 「S1」結構Si / Pt / GdFeCo / FeCo / barrier / FeCo / TbFeCo / Pt 29
4.3.2 「S2」結構Si / Pt / TbFeCo / FeCo / barrier / FeCo / GdFeCo / Pt 32
4.3.3 「S3」結構Si / Pt / GdFeCo / barrier / TbFeCo / Pt 35
4.3.4 「S4」結構Si / Pt / TbFeCo / barrier / GdFeCo / Pt 39
4.3.5 結果與討論 40
4.4 使用導電式原子力顯微探針量測鑄型化pMTJ的磁阻 41
4.4.1 動機與簡介 41
4.4.2 使用電子束微影與乾式離子蝕刻製作圖案化元件 41
4.4.3 量測技巧與接觸問題 44
4.4.4 量測以SiNx為穿遂絕緣層的pMTJ 47
4.4.5 pMTJ(SiNx絕緣層)製作成元件的磁滯曲線分析 50
4.4.6 pMTJ(SiNx絕緣層)TEM cross-section圖 51
4.4.7 結果與討論 52
4.5 設計使用電流平行膜面穿遂法量測磁阻 53
4.5.1動機與簡介 53
4.5.2光罩的設計與所設計的條件 55
4.5.3光阻塗佈與光微影製作流程 57
五、結論 59
5.1 總結 59
5.2 磁阻式隨機存取記憶體未來展望 59
參考文獻 61
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