臺灣博碩士論文加值系統

本論文藉由變化鋱鐵鈷合金(TbFeCo)的膜厚，利用其磁性質可調變之特性來應用於垂直式磁穿隧結面(perpendicular Magnetic Tunnel Junction；pMTJ)結構之自由層與固定層中。於實驗中鍍製不同組成比例與不同夾層之TbFeCo薄膜，其結構為P /TbFeCo / P，其中P為SiNx (10 nm)或Al (10 ~ 30 nm)。並使用交替式梯度測磁儀、退火爐、穿透式電子顯微鏡及磁性原子力顯微鏡等探討其磁性質變化。
在實驗中成功鍍製厚度為3nm且具有低矯頑場與低飽合磁化量之TbFeCo薄膜，Tb比例約為28~30%。與膜厚為35nm之傳統TbFeCo磁性層相比，矯頑場由3370 Oe下降至486 Oe，飽和磁化量由350 emu/c.c.下降至81 emu/c.c.。使用鋁作為上下夾層之結構其矯頑場隨鋁加入而上升，飽合磁化量則隨著之降低，在Al / Tb28(Fe80Co20)72 /Al此結構中會有最大的矯頑場與最低飽合磁化量，且磁滯曲線之方正性亦會有明顯改善。另一方面，在高溫退火處理後發現在TbFeCo膜厚為3nm夾層為鋁之TbFeCo磁性薄膜其矯頑場與飽和磁化量會隨著退火溫度增加呈現下降的趨勢，而方正性亦會隨退火溫度增加而有所改善。另外在Si /MgO /Al /TbFeCo /Al之結構中，隨絕緣層上插入之Al膜厚增加，仍具有矯頑場上升與飽和磁化量降低之現象，且在退火溫度100~150℃時可大幅改善磁滯曲線之方正性。

This thesis studies the magnetic characteristics of TbFeCo by varying thickness of TbFeCo thin films for the application of the free and the fixed layers of perpendicular magnetic tunnel junction (pMTJ). The effects of the layer structures with different buffer and capping layers of different thickness of aluminum (10 ~30 nm) or SiNx (10 nm) are investigated. The measurements of magnetic characteristics are carried out by alternating gradient magnetometer (AGM), transmission electron microscope (TEM), and magnetic force microscope (MFM), respectively. The terbium compositions of 3nm TbFeCo film is about 28~30%. In Comparison with 35nm TbFeCo, the coercivity drop to 486 Oe from 3370 Oe and the magnetization drop to 81 emu/c.c. from 350 emu/c.c. We found that the magnetic properties are improved by using aluminum instead of SiNx as capping and buffer layer. On the other hand, both the coercivity and magnetization decreases as annealing temperature increases. The hysteresis loop squareness also can be improved. In addition, the structures of Si/MgO/Al/TbFeCo/Al with various Al thickness above MgO are also explored. The coercivity increases and magnetization decreases as aluminum thickness increases. The loop squareness can be improved via the 100℃ and 150℃ annealing temperature.

中文摘要 ---------------------------------------------------------------------------- i
目錄 ---------------------------------------------------------------------------- ii
誌謝 ---------------------------------------------------------------------------- iii
目錄 ---------------------------------------------------------------------------- iv
表目錄 ---------------------------------------------------------------------------- vi
圖目錄 ---------------------------------------------------------------------------- vii
一、 緒論---------------------------------------------------------------------- 1
1.1 研究背景---------------------------------------------------------------- 1
1.2 研究動機---------------------------------------------------------------- 2
1.3 論文架構---------------------------------------------------------------- 3
二、 理論背景---------------------------------------------------------------- 4
2.1 磁學基礎理論---------------------------------------------------------- 4
2.1.1 磁性的來源------------------------------------------------------------- 4
2.1.2 磁性之分類------------------------------------------------------------- 4
2.2 稀土-過渡金屬合金的特性------------------------------------------ 7
2.2.1 RE-TM簡介------------------------------------------------------------ 7
2.2.2 RE-TM金屬合金之成分對磁化量與矯頑場之關係------------ 8
2.2.3 RE-TM金屬合金之磁性質與溫度之關係------------------------ 9
2.2.4 稀土-過渡金屬合金之垂直異向性--------------------------------- 11
2.3 磁性穿隧接面 (Magnetic Tunnel Junction, MTJ)---------------- 13
三、 實驗儀器與方法------------------------------------------------------- 15
3.1 薄膜濺鍍系統---------------------------------------------------------- 15
3.1.1 電漿放電原理---------------------------------------------------------- 16
3.1.2 直流濺鍍系統---------------------------------------------------------- 18
3.1.3 射頻濺鍍系統---------------------------------------------------------- 20
3.1.4 磁控濺鍍系統---------------------------------------------------------- 22
3.2 交替式梯度測磁儀(AGM)------------------------------------------- 24
3.3 穿透式電子顯微鏡(TEM)-------------------------------------------- 25
3.4 原子力顯微鏡(Atomic Force Microscope, AFM)----------------- 27
3.5 磁性原子力顯微鏡(Magnetic Force Microscope, MFM)-------- 27
四、 結果與討論------------------------------------------------------------- 30
4.1 不同Tb濺鍍功率之TbFeCo合金薄膜磁特性分析------------ 31
4.2 以Al為保護層對Tb28(Fe80Co20)72合金薄膜之影響------------ 42
4.2.1 以Al為保護層對厚度為35nm之Tb28(Fe80Co20)72薄膜磁特性比較-------------------------------------------------------------------
43
4.2.2 以Al為保護層對厚度為6nm之Tb28(Fe80Co20)72薄膜磁特性比較----------------------------------------------------------------------
49
4.2.3 以Al為保護層對厚度為3nm之Tb28(Fe80Co20)72薄膜磁特性比較----------------------------------------------------------------------
55
4.2.4 不同上下保護層對Tb28(Fe80Co20)72合金薄膜之TEM橫截面分析----------------------------------------------------------------------
61
4.2.5 以Al為保護層對Tb28(Fe80Co20)72合金薄膜之MFM磁區分析-------------------------------------------------------------------------
62
4.3 退火處理對Al作為保護層之Tb28(Fe80Co20)72薄膜磁性質之影響----------------------------------------------------------------------
64
4.4 不同Al厚度在Si / MgO 1nm / Al (X) / TbFeCo 3nm / Al 10nm結構之影響------------------------------------------------------
71
4.5 退火處理對Si / MgO 1nm / Al (X) / TbFeCo 3nm / Al 10nm結構之磁特性影響----------------------------------------------------
76
五、 結論---------------------------------------------------------------------- 85
六、 未來展望---------------------------------------------------------------- 87
參考文獻 ---------------------------------------------------------------------------- 88

1.M. N. Baibich, J. M. Broto, A. Fert, F. Nguyen Van Dau, F. Petroff, P. Etienne, G. Creuzet, A. Friederich and J. Chazelas, 1988, Phys. Rev. Lett, vol. 61, p.2472-2475.
2.J. S. Moodera, L. R. Kinder, T. M. Wong and R. Meservey, 1995, Phys. Rev. Lett. vol.74, p.3273-3276.
3.S. S. P. Parkin et al, 1999, J. Appl. Phys. vol.85, p.5828.
4.J. de Boeck and G. Borghs, 1999, Phys. World, vol.12, p.27.
5.S. Tehrani et al, 2003, Proc. IEEE, vol.91, p.714.
6.葉林秀、李佳謀、徐明豐、吳德和，磁阻式隨機存取記憶體技術的發展─現在與未來，物理雙月刊，廿六卷四期。
7.M. Durlam, D. Addie, J. Akerman, B. Butcher, P. Brown, J. Chan, M. Deherrera, et al., 2003, IEDM, pp. 34.6.1
8.J. DeBrosse, C. Arndt, C. Barwin, A. Bette, D. Gogl, et al., 2004, VLSI circuits, Dig. Tech. Papers 454
9.B. N. Engel, J. Åkerman, B. Butcher, R. W. Dave, et al., 2005, IEEE Trans. Mag., vol.41, no.1.
10.Thomas W. Andre, Joseph J. Nahas, Bradley J. Garni, et al., 2005, IEEE Journal of Solid-state circuits, vol.40, no.1.
11.N. Nishimura, T. Hirai, A. Koganei, T. Ikeda, K. Okano,Y. Sekiguchi, and Y. Osada, 2002, J. Appl. Phys., vol. 91, p.5246-5248
12.Hansen Peter, Heitmann Heinrich. IEEE Trans Magn,1989, 25(6): 4390-4404.
13.金重勳博士等，2002，磁性技術手冊，中華民國磁性技術協會，新竹。
14.R. J. Gambino, and T. Suzuki, Magneto-optical recording materials, IEEE Press, New York, 2000 (ISBN 0-780-31009-8)
15.C. J. Robinson, T. Suzuki, C. M. Falco, 1992, Materials for Magneto-Optic Data Stroage, Materials Research Society
16.Y. Suzuki, J. Haimovich, and T. Egami, 1987, Phys. Rev. B 35, 2162
17.G. S. Cargill, III and T. Mizogouchi, 1978, J. Appl. Phys. 49, 1753
18.L. Nẽel, J. Phys. Radium, 1954, 15, 225
19.T. Egami, C. D. Graham, Jr., W. Dmowski, P. Zhou, and P. J. Flanders, 1987, IEEE. Trans. Magn. MAG-23, 2269
20.Y. Suzuki, S. Takayama, F. Kirino, and N. Ohta,1987, IEEE Trans. Magn. MAG-23, 2275
21.M.S.S. Brooks, 1991, L. Nordstroem, and B. Johanaaon, Physica B: Condensed Matter. 177, 95
22.M. Chikazumi,1964, “ Physics of magnetism”, New York: John Wiley
23.S. Tsunashima, H. Takagi, K. Kamegki, T. Fujii, and S. Uchiyama, IEEE Trans. Magn. MAG-14, 844 (1987)
24.B. D. Cullity, 1972, Introduction to magnetic materials
25.Shih-Cheng N. Cheng and Mark H. Kryder, 1991, J. Appl. Phys. 69, 7202
26.Y. Suzuki, S. Takayama, F. Kirino, and N. Ohta, 1987, IEEE Trans. Magn. MAG-23, 2275
27.T. Miyazaki, N. Tezuka, 1995, vol.139, p.L231-L234
28.W. J. Gallagher, S. S. P. Parkin, X. P. Bian, R.A. Altman and G. Xiao, 1997, J. Appl. Phys. vol.81 p.3741-3746
29.陳咨融，2006，穿隧式磁阻結構製備與磁特性之研究，雲林科技大學，碩士論文，p.15。