臺灣博碩士論文加值系統

本實驗以磁控濺鍍法製備FePt薄膜及Pt/FePt及Ge-Pt/FePt雙層膜於石英基板上，並改變底層之膜厚及熱處理以研究其對矯頑磁力的影響。
膜厚60 nm的FePt單層薄膜經過400℃後退火的序化熱處理可獲得6.3 kOe之最佳的矯頑磁力，且400℃的序化溫度是FePt單層薄膜的最低序化溫度，低於400℃則FePt磁性薄膜則無法序化為L10序化相。而隨著序化溫度的增加，其矯頑磁力與序化度亦隨之增加。
在Pt/FePt雙層膜物系的研究發現，對Pt底層做一段式熱處理(即後退火)或兩段式熱處理(即在相同温度做基板預熱和後退火)，則雙層膜之Hc值將有不同的結果，前者的Hc值將隨著後退火温度(Ta)的升高而降低，在Ta= 600℃達到最低值5.5 kOe；後者的Hc值將隨著兩段式熱處理溫度(Ti)的升高而增加，在Ti= 600℃達到最大值8.8 kOe。這種差異是起因於熱處理方式的不同，致使Pt底層與基板間產生不同的應力作用－即壓縮應力或拉伸應力，前者不利於FePt薄膜的序化，後者則有助於提升序化度，而這兩種應力皆起源於基板與Pt底層間之熱膨脹係數的差異。
在Ge-Pt/FePt雙層膜物系的研究顯示，熱膨脹係數差異所引起的應力對FePt薄膜未有顯著作用，因此其Hc值隨著熱處理溫度的變化趨勢不隨一段式或兩段式而異，Hc值隨著Ta或Ti的提升而增加。對Ge-Pt底層施以Ta = 600℃的後退火熱處理，則雙層膜最後可得8.5 kOe的矯頑磁力，在600℃施以兩段式底層熱處理，可使雙層膜的矯頑磁力高達10.0 kOe。由於Ge-Pt底層的熱處理溫度越高將形成更多Ge3Pt2相，可阻止不利於序化的Ge原子擴散進入FePt薄膜，故可顯著提升其矯顽磁力。

In this study, FePt films and (Pt, Ge-Pt)/FePt bilayer samples are deposited on quartz by magnetron sputtering. The microstructure and magnetic properties of FePt were studied by controlling the thickness and annealing treatment of underlayers. The highest coercivity of FePt single layer, 6.3 kOe, was obtained by post-annealing the FePt (60 nm) sample. The lowest ordering temperature of FePt is 400℃. Coercivity is increased by raising the ordering temperature.
In the Pt/FePt bilayer system, different coercivities were obtained as one-step heat treatment (post annealing at Ta) or two-step heat treatment (in-situ annealing plus post annealing at a specified temperature Ti) were employed to the Pt underlayer. Coercivity decreases with the increasing Ta, down to a minimum value 5.5 kOe at Ta= 600℃. On the contrary, Hc increases with the increasng Ti. A maximum Hc value of 8.8 kOe was obtained at Ti = 600℃. The different variations of Hc with heat treating temperatures (Ta or Ti) could be explained by the states of residual stress in the underlayer (either tensile or compressive stress) resulting from the different thermal expansion coefficients of quartz substrate and Pt underlayer. A tensile stress suppresses the ordering process of FePt layer while a compressive stress promotes.
In the Ge-Pt/FePt bilayer system, the thermal stress induced in the Ge-Pt underlayer is negligible. Therefore, the trends of Hc vs. Ta and Hc vs. Ti are similar. Hc increases with arising heat treatment temperatures. The coercivity of 8.5 kOe was obtained as a Ge-Pt (60 nm)/FePt (60 nm) sample was annealed at Ta= 600℃. A two-step annealing at Ti = 600℃ led to a even higher Hc value of 10.0 kOe. Because more Ge3Pt2 was formed at high annealing temperature, less Ge atoms which are harmful for ordering transformation could diffuse to the magnetic FePt layer. Coercivities of the bilayer samples were thus highly enhanced.

總目錄

摘要……………………………………………………………………….i
Abstract………………………………………………………………….iii
總目錄…………………………………………………………………....v
圖目錄…………………………………………………………………...xi
表目錄………………………………………………………………....xvii
符號說明……………………………………………………….……..xviii
第一章 緒論……………………………………………………………1
1-1 前言……………………………………………………………1
1-2 功能性磁性材料之發展……………………………………....2
1-3 背景及動機……………………………………………………3
1-3-1 背景……………………………………………………..3
1-3-2 動機……………………………………………………..4
第二章 基礎理論與文獻回顧…………………………………………6
2-1 理論基礎………………………………………………………6
2-1-1 FePt合金之結構………………………………………..6
2-1-2 GePt合金之組成…………………………………….....9
2-1-3 序化與非序化…………………………………………11
2-1-4 磁滯曲線與磁硬化機構………………………………14
2-2 文獻回顧……………………………………………………..19
2-2-1 FePt薄膜………………………………………………19
2-2-2 FePt底層效應 (Underlayer Effect）…………………27
2-3 濺鍍原理……………………………………………………..32
2-3-1 電漿原理………………………………………………33
2-3-2 射頻放電………………………………………………33
2-3-3 磁控濺鍍法……………………………………………35
2-4 薄膜成長理論………………………………………………..36
第三章 實驗步驟與方法……………………………………………..38
3-1 實驗流程……………………………………………………..38
3-2 濺鍍系統裝置………………………………………………..40
3-3 實驗材料……………………………………………………..41
3-4 鍍膜程序與參數設定………………………………………..45
3-4-1 退火處理………………………………………………45
3-5 薄膜性質量測………………………………………………..47
3-5-1 膜厚與鍍率之量測……………………………………47
3-5-2 成分分析………………………………………………48
3-5-3 SIMS 薄膜分析………………………………………49
3-5-4 XRD分析……………………………………………...49
3-5-5 磁性分析………………………………………………49
3-5-6 TEM微結構觀察……………………………………...50
第四章 結果與討論…………………………………………………..54
4-1 FePt二元合金單層薄膜之討論……………………………..54
4-1-1 FePt薄膜之磁性質……………………………………54
4-1-1-1 FePt 薄膜厚度對磁性質之影響………………55
4-1-1-2 FePt 薄膜退火溫度對磁性質之影響…………56
4-1-2 FePt薄膜之XRD繞射………………………………57
4-1-2-1 FePt晶格常數…………………………………..58
4-1-2-2 FePt序化度……………………………………..61
4-1-3 FePt 薄膜之微結構…………………………………..62
4-2 Pt底層對FePt薄膜之影響…………………………………67
4-2-1 Pt底層之厚度 (tPt) 對FePt薄膜之影響……………..67
4-2-1-1 Pt底層厚度對FePt 薄膜磁性質之影響………67
4-2-1-2 Pt底層厚度對FePt薄膜之XRD繞射……….70
4-2-1-2-1 XRD繞射………………………………..70
4-2-1-2-2 晶格常數………………………………...71
4-2-1-2-3 序化度…………………………………...73
4-2-1-3 Pt底層厚度對FePt薄膜顯微結構……..…….74
4-2-2 Pt底層之後退火處理溫度 (Ta) 對FePt薄膜之影響……………………………………………………77
4-2-2-1 Pt底層後退火處理溫度對FePt 薄膜磁性質之影響………………………………………………77
4-2-2-2 Pt底層後退火熱處理溫度對FePt薄膜之XRD繞射……………………………………………79
4-2-2-2-1 XRD繞射………………………………..79
4-2-2-2-2 晶格常數………………………………...81
4-2-2-2-3 序化度…………………………………...84
4-2-2-3 Pt底層後退火熱處理溫度對FePt薄膜顯微結構………………………………………………..85
4-2-3 Pt底層之基板預熱加後退火熱處理溫度 (Ti) 對FePt薄膜之影響……………………………..…………..88
4-2-3-1 Pt底層之基板預熱加後退火熱處理溫度對FePt 薄膜磁性質之影響……………………………..88
4-2-3-2 Pt底層之基板預熱加後退火熱處理溫度之XRD繞射……………………………………………90
4-2-3-2-1 XRD繞射………………………………..90
4-2-3-2-2 晶格常數………………………………...91
4-2-3-2-3 序化度…………………………………...95
4-2-3-3 Pt底層基板預熱加後退火熱處理溫度對FePt薄膜顯微結構之研究……………………………..97
4-3 Ge-Pt底層對FePt薄膜之影響……………………………..101
4-3-1 Ge-Pt底層後退火熱處理溫度 (Ta) 對FePt薄膜之影響……………………………………………………101
4-3-1-1 Ge-Pt底層後退火熱處理溫度對FePt 薄膜磁性質之影響 (Ta)………………………………..103
4-3-1-2 Ge-Pt底層後退火熱處理溫度之XRD繞射...108
4-3-1-2-1 XRD繞射………………………………108
4-3-1-2-2 晶格常數……………………………….109
4-3-1-2-3 序化度………………………………….110
4-3-1-3 Ge-Pt底層後退火熱處理溫度對FePt 薄膜顯微結構之研究……………………………………112
4-3-2 Ge-Pt底層基板預熱加後退火熱處理溫度 (Ti) 對FePt薄膜之影響……………………………….………...115
4-3-2-1 Ge-Pt底層基板預熱加後退火熱處理溫度對FePt 薄膜磁性質之影響……………………………115
4-3-2-2 Ge-Pt底層基板預熱加後退火熱處理溫度之XRD繞射..…………………………………..120
4-3-2-2-1 XRD繞射………………………………120
4-3-2-2-2 晶格常數……………………………….121
4-3-2-2-3 序化度……………………………….....122
4-3-2-3 Ge-Pt底層基板預熱加後退火熱處理溫度對FePt 薄膜顯微結構…………………………………124
第五章 結論…………………………………………………………127
第六章 未來展望及研究建議………………………………………129
參考文獻………………………………………………………………130
著作列表…….………………………………………………………...140

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