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研究生:林季宏
研究生(外文):Ji-Hong Lin
論文名稱:軟鐵磁層對垂直異向性FePt/Pt/Cr三層結構之耦合交換力效應探討
論文名稱(外文):Exchange-spring effect of soft Fe top layer onto perpendicular magnetic anisotropy FePt/Pt/Cr trilayer
指導教授:郭博成
指導教授(外文):Po-Cheng Kuo
學位類別:碩士
校院名稱:國立臺灣大學
系所名稱:材料科學與工程學研究所
學門:工程學門
學類:材料工程學類
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:89
中文關鍵詞:交換耦合交換彈力垂直異向性
外文關鍵詞:exchange couplingexchange springperpendicular magnetic anisotropy
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當前水平磁記錄發展已達上限,若要繼續提升記錄密度,必須朝向垂直磁記錄發展,目前製作垂直記錄媒體面臨的困難有:易磁化方向不易在垂直膜面方向、序化溫度過高、矯頑磁力過高等問題,近幾年來前兩項問題已逐漸被克服,但是矯頑磁力過高的問題仍有待解決,因此本實驗藉由改變製程方法來改善上述所說的問題。
本文研究在於利用交換彈力系統的概念,將軟磁層Fe濺鍍在硬磁層FePt(001)薄膜之上,藉由改變濺鍍Fe之溫度、瓦數、厚度,以期許可降低Cr/Pt/FePt/Fe之Hc,進而改善磁頭寫錄的問題。我們並發現濺鍍Fe之溫度與瓦數,並不會對結構或是磁性質有顯著的影響,Fe厚度的改變雖然也不會改變結構,但是對Cr/Pt/FePt/Fe磁性質卻有明顯的變化,當Fe厚度薄時(3、5 nm),在Fe和FePt界面僅有弱的交換耦合力產生,Fe厚度是10 nm時,此時交換耦合力為最強,厚度再增加到15、20 nm時,Hc反而略為上升,同樣的我們量測DCD曲線,也證實了Fe厚度10 nm的確有交換耦合力存在。Cr/Pt/FePt三層結構的垂直方向Hc為2565 Oe,出現最強交換耦合力時,Hc可下降至1312 Oe,這說明了當交換耦合力發生之時Hc可有效降低達50%,這將大幅解決垂直記錄媒體在寫錄時,磁矩不易翻轉的問題。
Nowadays, the areal density of longitudinal magnetic recording reaches their limits. If we keep on upgrading its recording densities, the only way is developing the perpendicular magnetic recording. But, some manufacturing issues of perpendicular magnetic recording need to be solved. For example: tilted easy axis to the film plane, higher soft-hard phase transition temperature, and large writing field of magnetic head to switch the moment of hard phase. In recent years, two problems, tilted easy axis and higher soft-hard phase transition temperature, were solved by epitaxial growth method. However, large writing field of head still confused the researchers.
In this investigation, in order to reduce the writing field of magnetic head, we reduced the film coercivity by controlling depositing parameters. The concept of “Exchange Spring” was presented in our study. The film coercivity was largely reduced by capping a soft Fe layer on hard FePt(001) thin films. We found that the microstructures and magnetic properties were not influenced with depositing temperature and sputtering power. The magnetic properties were only affected by Fe layer thickness. When the Fe layer thickness is thinner than 5 nm, weak exchange coupling raised between Fe cap layer and FePt recording layer. When the thickness reached 10 nm, the strongest exchange coupling formed. Film coercivity didn’t distinctly vary as Fe layer thickness is thinner than 15 nm. Consequently, we measured DCD curves and had the same conclusions. Indeed, the appearance of exchange coupling is confirmed with 10 nm Fe cap layer. In our study, out-of-plane coercivity of Cr/Pt/FePt trilayer film is 2565 Oe. When the strongest exchange coupling appears between soft Fe cap layer and hard FePt(001) film, out-of-plane coercivity can be efficiently reduced to about 50%. This will solve the writing problem of perpendicular magnetic recording.
第一章 前言........................................................................................1
1-1 緒論……………………………………………...…...….……...1
1-2 研究動機……………………...…………………...…....………5
第二章 相關資料及研究結果……….……………...……………6
2-1 磁記錄簡介……………..………..………………...…………...6
2-1-1 水平磁記錄(LMR)…………..………………...…………..6
2-1-2 垂直磁記錄(PMR)………………………….…...…………7
2-2 垂直記錄的優勢與限制………………………….…...………..8
2-3 交換彈力(Exchange Spring)概念的引用…………….……...…9
2-4 FePt與Fe之材料特性………………………………………….10
2-5 動態與靜態量測參數……………………………………….…11
2-5-1 靜態參數……………………………………………..……11
2-5-2 動態參數………………………………………………..…12
2-6 垂直記錄文獻回顧……………………………………………..13
2-6-1 FePt合金…………………………………………..………13
2-6-2 Exchange Spring…………………………………………..15
第三章 實驗方法………………………………………………….34
3-1 實驗流程………………………………………………………34
3-2 靶材選擇………………………………………………………35
3-2-1 底層靶材…………………………………………………..35
3-2-2 擴散阻礙層靶材….…..……………………...……………35
3-2-3 軟磁層靶材………………………………………………..35
3-2-4 硬磁層靶材………………………………………………..35
3-2-5 保護層靶材………………………………………………..35
3-3 基板準備……………………………………………………….36
3-3-1 基板選取……………………………….…….……………36
3-3-2 基板清洗………………………………………….……….36
3-4 機台設備及薄膜製備……………………………..…………...36
3-4-1 儀器設備…………………………………………………..36
3-4-2 交換彈力系統濺鍍………………………………………..37
3-5 試片分析…………..……………………………….......................38
3-5-1 AFM試片膜厚測定……………………………………….38
3-5-2 EDS成份分析……………………………………………..39
3-5-3 Auger縱深分析…………………………………………...39
3-5-4 XRD結構分析…………………………………………….40
3-5-5 TEM微結構觀察………………………………………….40
3-5-6 VSM磁性質量測………………………………………….42
第四章 實驗結果與討論…………………………………………49
4-1 Cr/Pt/FePt 三層膜之結構與磁性質……………………………..49
4-1-1 Cr底層的建構…………………………………….………49
4-1-2 Pt擴散障礙層的加入……………………………………..50
4-1-3 FePt層厚度以及成份的決定……………………………..50
4-1-4 Cr/Pt/FePt三層薄膜之結構與磁特性……………..…..…51
4-2 單層Fe之性質分析與探討………………………………………53
4-2-1 Fe單層結構分析………………………………………….53
4-2-2 Fe單層磁性值分析……………………………………….54
4-3 加上Fe頂層對Cr/Pt/FePt三層膜之結構及磁性質的影響…..55
4-3-1 Fe頂層加上後溫度對於Cr/Pt/FePt/Fe膜層結構及磁性質的影響……………………………………………………………….55
4-3-1-(a) 結構鑑定………………………………………………55
4-3-1-(b) 磁性分析………………………………………………56
4-3-2 Fe頂層濺鍍瓦數對於Cr/Pt/FePt/Fe膜層結構及磁性質的影響……………………………………….………………57
4-3-2-(a) 結構鑑定………………………………………………57
4-3-2-(b) 磁性分析………………………………………………57
4-3-3 軟磁層Fe厚度對於Cr/Pt/FePt/Fe膜層結構及磁性的影響………………………………………………………….59
4-3-3-(a) 結構鑑定………………………………………………59
4-3-3-(b) 磁性分析………………………...…………………….59
4-3-3-(b)-1 DCD(DC-demagnetization)曲線……………………60
第五章 結論………………………………………………………...80
5-1 Cr/Pt/FePt 三層膜之結構與磁性質……………………………..80
5-2 Fe單層性質分析與探討…………………………………………80
5-3 加上Fe頂層對Cr/Pt/FePt三層膜之結構及磁性質的影響……81
第六章 參考文獻…………………………………………………..83

圖目錄
圖1-1 第一個商用化硬碟-RAMAC………………………………..…3
圖1-2 磁頭進化示意圖……………………………………..…………3
圖1-3 Hitachi開發的垂直記錄硬碟……………………...…………..4
圖2-1 水平記錄過程…………………………………………………21
圖2-2 垂直記錄過程…………………………………………………21
圖2-3 垂直記錄薄膜結構……………………………………………22
圖2-4 磁記錄的三要素………………………………………………23
圖2-5 磁矩隨外加磁場翻轉之情況…………………………………23
圖2-6 FePt二元合金相圖……………………………………………24
圖2-7 (a)無序面心立方FePt軟磁相與(b)有序面心正方FePt硬磁相之晶體結構……………………………………………………..25
圖2-8 退火之Fe-Pt單層XRD繞射圖………………….…………27
圖2-9 FePt單層與FePt/Fe多層膜之磁能積……………………….27
圖2-10 In添加對於磁化量與矯頑磁力的影響……….………….…28
圖2-11 FePt與Fe3Pt之界面TEM照片……………….……………28
圖2-12 不同Si3N4厚度之下的磁滯曲線………………….………...29
圖2-13 不同Si3N4厚度之下成核場以及不可逆場的變化關係……29
圖2-14 軟磁層厚度與成核場的對應關係圖………………………..30
圖2-15 退火溫度對Sm-Co/Fe系統之去磁曲線…………………….30
圖2-16 Sm(Co,Cu)5/Fe之XRD………………………………………31
圖2-17 Sm(Co,Cu)5/Fe之磁滯曲線……………………………….…31
圖2-18 NdFeB/Fe退火後之XRD……………………………………32
圖2-19 改變NdFeB/Fe層數所對應之Hc與Mr關係….…………...32
圖2-20 FePt單層與FePt/Fe多層之磁滯曲線與去磁化曲線圖…....33圖3-1 實驗流程圖................................................................................34圖3-2 超高真空多層膜濺鍍系統俯視圖……....………...………….44圖3-3 超高真空多層膜濺鍍系統外貌……………...……………….44圖3-4 AFM膜厚示意圖………………...……………………………45圖3-5 AFM表面輪廓………………………...……………………....45圖3-6 EDS原理示意圖…………..…………………….…………….46圖3-7 AES電子位能示意圖…………..………………….………….46圖3-8 AES縱深元素分佈分析原理示意圖……..………….……….47圖3-9 XRD裝置圖……………...……………………………………47圖3-10 VSM裝置圖………………...………………………………..48
圖4-1 Cr單層膜之XRD繞射圖形……………………………….…63
圖4-2 Cr[110](002)∥FePt [001](200)磊晶關係示意圖………63
圖4-3 Cr/FePt之XRD繞射圖……………………………………….64
圖4-4 Auger元素縱深分析[67]……………………………………….64
圖4-5 Pt堆疊在Cr底層之XRD繞射圖…………………………..…65
圖4-6 Fe 18W與Pt 10W之EDX成份分析………………………....66
圖4-7 Fe 20W與Pt 10W之EDX成份分析………………………....67
圖4-8 Fe 22W與Pt 10W之EDX成份分析………………………....68
圖4-9 Cr/Pt/FePt三層膜之結構示意圖…………………………..…69
圖4-10 Cr/Pt/FePt三層膜之XRD繞射圖………………………….69
圖4-11 Cr/Pt/FePt三層膜之TEM橫截面圖[67]…………………….70
圖4-12 Cr/Pt/FePt三層膜之磁滯曲線圖……………………………70
圖4-13 單層Fe之XRD繞射圖……………………………………..71
圖4-14 康寧玻璃之逆磁訊號……………………………………..…71
圖4-15(a) 單層Fe不同厚度之水平方向磁滯曲線………………….72
圖4-15(b) 圖4-15(a)在原點附近之放大圖………………………….72
圖4-16 單層Fe不同厚度之垂直方向磁滯曲線…………………….73
圖4-17 Fe頂層之濺鍍溫度不同時之XRD繞射圖………………....73
圖4-18 Fe頂層之濺鍍溫度不同時之水平方向磁滯曲線……….…74
圖4-19 Fe頂層之濺鍍溫度不同時之垂直方向磁滯曲線………….74
圖4-20 Fe頂層之濺鍍溫度不同對Hc的影響……………………….75
圖4-21 Fe頂層不同濺鍍瓦數之XRD繞射圖……………………...75
圖4-22 Fe頂層不同濺鍍瓦數之水平方向磁滯曲線.........................76
圖4-23 Fe頂層不同濺鍍瓦數之垂直方向磁滯曲線……………….76
圖4-24 Fe頂層之濺鍍瓦數對Hc的影響……………………………77
圖4-25 不同Fe頂層厚度之XRD繞射圖…………………………..77
圖4-26 不同Fe頂層厚度之水平方向磁滯曲線…………………….78
圖4-27 不同Fe頂層厚度之垂直方向磁滯曲線………………….....78
圖4-28 Fe頂層厚度與垂直方向Hc之關係圖………………………79
圖4-29 FePt/Pt/Cr三層膜之DCD曲線…………………………….79
圖4-30 Fe(10nm)/FePt/Pt/Cr之DCD曲線…………………………80


表目錄
表2-1 目前的高Ku材料……………………………………………...22
表2-2 FePt之JCPD資料……………………………………………26
表2-3 Fe之JCPD資料……………………………………………….26
表2-4 FePt與Fe之材料特性………………………………………..10
表3-1 實驗參數表……………………………………….…………...38
表4-1 Cr/Pt/FePt之磁性質…………………………………………..52
表4-2 Fe頂層加上後對Cr/Pt/FePt磁性質的變化………………….56表4-3 不同瓦數相同厚度及溫度之磁性質…………………………59
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