臺灣博碩士論文加值系統

本研究主要是針對氮化矽下底層之應力狀態對於氮化矽/鋱鐵鈷/氮化矽磁光三層薄膜之磁性質與紀錄特性的影響，藉由調整沉積氮化矽下底層時的工作氣壓、氬/氮反應氣體比、與膜層厚度，我們發現當氮化矽下底層具有較大的殘餘壓應力，鋱鐵鈷磁性層會呈現較佳的垂直異向性，而且其磁滯方正性也會隨之提昇。
藉由初始磁滯曲線的分析，鋱鐵鈷薄膜的磁化翻轉機制也受氮化矽下底層應力狀態的影響。當調整工作氣壓使所沉積的氮化矽下底層產生一殘餘壓應力，鋱鐵鈷磁性層的翻轉機制會趨向於成核翻轉機制。
由記錄特性之研究中發現當下底層的氮化矽薄膜具有較大的壓應力狀態時，鋱鐵鈷紀錄層會因垂直異向性的強化而導致雜訊的下降。最後，由實驗的結果可計算出該碟片的紀錄密度可達10 Gbit/inch2。

This work studied the effects of stress statuses of SiNx underlayer on the magnetic and recording properties of SiNx/TbFeCo/SiNx trilayers. By adjusting the deposited parameters of SiNx underlayer, such as working pressure, Ar/N2 ratio, and thickness, the TbFeCo might exhibit strong perpendicular anisotropy when SiNx underlayer possessed large compressive stress. We also found that the compressive stress enhanced the coercivity squareness of TbFeCo.
The observation of initial M-H curves revealed that the switching mechanism of TbFeCo strongly depended on the deposition conditions of SiNx underlayer. When the SiNx underlayers were subjected to a compressive stress, magnetization switching of TbFeCo films preferred the nucleation mechanism. The contribution of compressive stress to magnetization reversal was obvious when changing the working pressure of deposition.
The experiment of recording properties indicated that the media noise could be effectively reduced when the SiNx underlayer possessed a strong compressive stress. The compressive stress status also enhanced the perpendicular unaxial anisotropy (Ku) of MO trilayer. Our experimental results indicated that the storage density of MO disk could reach about 10 Gbit/inch2.

中文摘要 i
Abstract ii
誌謝 v
Contents vi
Figure Coaptions ix
Tabl Table Captions xv
List of Symbols xvi
Chapter 1 Introduction 1
Chapter 2 Literatue Review 5
2.1 Magnetic Properties of Hystersis Loop 5
2.2 Mechanism of Magneto-optical Recording 6
2.3 Structure of Magneto-optical (MO) Disk 8
2.3.1 The Recording Layer Materials 8
2.3.1.1 The MnBi Aolly 8
2.3.1.2 Garnet and Ferrite Thin Films 8
2.3.1.3 Multilayer magnetic Thin Films 9
2.3.1.4 The RE-TM Alloys 9
(a) The Crystal Structure of RE-TM Alloys 10
(b) Magnetic Properties of RE-TM Alloys 10
(b)-1 Ferrimagnetic Materials 10
(b)-2 Perpendicular Anisotropy 10
(b)-3 Composition and Temperature Dependence of Magnetic Properties 11
(b)-4 The Magneto-optical Effect 12
(c) The Drawbacks of RE-TM Alloys 12
2.3.2 The Dielectric Layer Materials 13
2.3.2.1 Silicon Nitride Thin Film 14
2.4 The Origin of Anisotropy 15
2.4.1 Magnetocrystalline and Shape Anisotropy 15
2.4.2 Magnetostriction and Stress Status 15
2.4.3 Enhancement the Anisotropy of RE-TM Alloys 17
2.5 Reversal Mechanisms 19
Chapter 3 Experimental 21
3.1 Experimental Flow Chart 21
3.2 The SiNx Thin Film Sample for Residual Stress and Surface Roughness Measurement 22
3.2.1 Fabrication of SiNx Thin Films 22
3.2.2 Measurements of Residual Stress and Surface Roughness 22
3.3 Magnetic Properties of MO Trilayer 23
3.3.1 Fabrication of MO Trilayers 23
3.3.2 Analysis of Magnetic Properties 24
3.4 Composition Analysis 25
3.5 Effects of Underlayer Roughness upon Magnetic Behavior of MO Trilayers 25
3.6 The Effects of Stress Status of SiNx Underlayer on the Magnetic Behavior of MO Trilayers 27
3.7 Signal Properties Tests 27
3.7.1 Fabrication of MO Disks 27
3.7.2 Signal Property Tests in Hard-disc System 29
Chapter 4 Results and Discussion 31
4.1 Effect of Stress Status of SiNx Underlayer upon the Magnetic Properties of MO Trilayers 31
4.1.1 Effect of Total Working Pressure of SiNx Underlayer upon the Magnetic Properties 31
4.1.2 Effect of Ar/N2 Ratio of SiNx Underlayer upon the Magnetic Properties 37
4.1.3 Effect of Thickness of SiNx Underlayer upon the Magnetic Properties 39
4.1.4 Effect of Annealing Treatment of SiNx Underlayer upon the Magnetic Properties 42
4.2 Effect of Substrate Roughness upon the Magnetic Properties 43
4.3 Recording Characteristics of MO Disk Samples 48
4.3.1 Type 1: Change of Underlayer Thicknesses 50
4.3.2 Type 2: Change of Upper Dielectric Layer Thicknesses 56
4.3.3 Type 3: Change of the Coercivity of TbFeCo Layer 60
4.3.4 Type 4: Change of TbFeCo Layer Thickness 65
Chapter 5 Conclusions 72
References 74

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