本論文使用反應性射頻磁控濺鍍法，利用濺鍍條件為濺鍍功率370W、腔室壓力15mTorr、氮氣濃度為40%及30%、基板溫度400℃，分別將高C軸排向的氮化鋁(AlN)薄膜沈積在Z軸切面LiNbO3基板及ST切面石英基板上。
本研究亦藉由XRD、SEM與AFM分析AlN薄膜以不同的厚度沈積在LiNbO3及ST切面石英基板上的結果，並討論其材料特性。
另外，在不同厚度的AlN薄膜上製作指叉換能器，以探討膜厚在雙壓電層結構對SAW元件之影嚮以及AlN薄膜本身的頻率溫度係數(Temperature coefficient of frequency, TCF)大小。由實驗結果得知，隨著AlN薄膜厚度的增加，表面聲波濾波器的中心頻率及TCF亦隨之增加；並且證實了AlN薄膜本身的TCF確為正值。

In this study, we use the reactive rf magnetron sputtering method with deposition parameters of RF power of 370W, sputtering pressure of 15 mTorr, substrate temperature of 400℃, nitrogen concentration (N2/N2+Ar) of 30% and 40%, to deposit highly c-axis orientation AlN thin films on Z-cut LiNbO3 and ST-cut quartz piezoelectric substrate, respectively.
The material characteristics of AlN films deposited on Z-cut LiNbO3 and ST-cut quartz substrate with different thickness were obtained by means of the analyses of XRD, SEM and AFM. Besides, the interdigital transducers (IDTs) were fabricated on the bi-layers structure. The AlN film thickness of piezoelectric bi-layers structure was varied in order to discuss its effect on SAW devices and the temperature coefficient of frequency (TCF) of AlN. From the experimental results, it reveals that the center frequency and TCF of SAW filters increase with the increased AlN thin film thickness. Besides it can be concluded that poly-crystalline AlN exhibits a positive temperature coefficient of frequency (TCF).

目錄
摘要 I

目錄 III

圖表目錄 V

第一章 前言 1

第二章 理論 5
2.1 AlN結構與特性 5
2.2 LiNbO3結構與特性 6
2.3 反應性射頻磁控濺鍍原理 7
2.3.1 輝光放電 7
2.3.2 磁控濺鍍 8
2.3.3 射頻濺射 9
2.3.4 反應性濺射 9
2.4 SAW元件的理論與特性 10
2.4.1 SAW元件的特點 10
2.4.2 SAW元件的基本設計 11
2.5 SAW元件的參數性質 11
2.5.1 Vp測量 11
2.5.2 IL測量 12
2.5.3 K2測量 13
2.5.4 TCF測量 14

第三章 實驗 15
3.1 基板的清洗 15
3.2 濺鍍系統與薄膜沉積 16
3.3 X光繞射 (X-Ray Diffraction, XRD) 分析 17
3.4 掃描式電子顯微鏡(Scanning Electron Microscopy, SEM)分析 18
3.5 原子力顯微鏡(Atomic Force Microscopy, AFM)分析 18
3.6 SAW元件的製作 19
3.7 光學顯微鏡分析 20
3.8 電路板製作 20
3.9 元件測量 21

第四章 結果與討論 22
4.1 XRD分析 22
4.1.1 AlN/LiNbO3結構的XRD分析 22
4.1.2 AlN/ST-quartz結構的XRD分析 22
4.2 SEM分析 23
4.2.1 AlN/LiNbO3結構的SEM分析 23
4.2.1 AlN/ST-quartz結構的SEM分析 23
4.3 原子力顯微鏡(AFM)分析 23
4.3.1 AlN/LiNbO3結構的AFM分析 24
4.3.2 AlN/ST-quartz結構的AFM分析 24
4.4 指叉換能器(IDTs)製作 24
4.5 SAW元件分析 25
4.5.1 Vp的量測 25
4.5.1.1 AlN/LiNbO3結構的Vp測量 25
4.5.1.2 AlN/ST-quartz結構的Vp測量 26
4.5.2 TCF的測量 26
4.5.2.1AlN/ST-quartz結構的TCF測量 27
4.5.2.2 AlN/LiNbO3結構的TCF測量 27

第五章 結論 29

參考文獻 31






圖 表 目 錄
圖1-1 SAW元件的基本結構：(a)塊體元件，(b)薄膜元件 39
圖1-2 雙壓電層結構之SAW元件 40
圖2-1 AlN的晶體構造：（a）變形四面體結構，（b）單位晶胞圖，（c）纖鋅礦之立體結構示意圖，其中黑球代表鋁原子，白球代表氮原子 41
圖2-2 複三方錐面示意圖 42
圖2-3 （a）當溫度低於居里溫度時，LiNbO3晶體呈現鐵電性
（b）當溫度高於居里溫度時，LiNbO3晶體呈現順電性 42
圖2-4 直流輝光放電結構與電位分佈圖 43
圖2-5 平面型圓形磁控之結構圖 44
圖2-6 平面磁控結構及電子運動路徑圖 44
圖2-7 反應性濺射之模型 45
圖2-8 由縱波與剪波組合而成的SAW：（a）縱波傳播模式，（b）剪波傳播模式，（c）SAW傳播模式 46
圖2-9 設計SAW元件的窗口函數技術 47
圖3-1 射頻磁控濺鍍系統構造圖 48
圖3-2 射頻濺鍍系統操作之流程圖 49
圖3-3 IDT 電極製作之流程圖 50
圖3-4 舉離法製程之示意圖 51
圖3-5 電路板之設計圖 52
圖4-1 不同濺鍍時間下，AlN薄膜沈積在LiNbO3基板上之XRD圖；固定條件為濺鍍功率370W、腔室壓力15mTorr、氮氣濃度40﹪、基板溫度400℃ 53
圖4-2 不同濺鍍時間下，AlN薄膜沈積在ST-quartz基板上之XRD圖；固定條件為濺鍍功率370W、腔室壓力15mTorr、氮氣濃度30﹪、基板溫度400℃ 54
圖4-3 不同濺鍍時間下，AlN薄膜沈積在LiNbO3基板上之表面的SEM照片；固定條件為濺鍍功率370W、腔室壓力15mTorr、氮氣濃度40﹪、基板溫度400℃、氮氣濃度60﹪、基板溫度400℃ 55
圖4-4 不同濺鍍時間下，AlN薄膜沈積在LiNbO3基板上之剖面的SEM照片；固定條件為濺鍍功率370W、腔室壓力15mTorr、氮氣濃度40﹪、基板溫度400℃;圖(a)中的Bar為0.25μm。圖(b)及圖(c)中的Bar為1μm。 56
圖4-5 AlN薄膜沈積在LiNbO3基板上的濺鍍時間對薄膜厚度之關係 51
圖4-6 不同濺鍍時間下，AlN薄膜沈積在ST-quartz基板上之表面的SEM照片；固定條件為濺鍍功率370W、腔室壓力15mTorr、氮氣濃度30﹪、基板溫度400℃。 58
圖4-7 不同濺鍍時間下，AlN薄膜沈積在ST-quartz基板上之剖面的SEM照片；固定條件為濺鍍功率370W、腔室壓力15mTorr、氮氣濃度30﹪、基板溫度400℃;圖(a)中的Bar為0.25μm。圖(b)及圖(c)中的Bar為1μm。 59
圖4-8 AlN薄膜沈積在LiNbO3基板上的濺鍍時間對薄膜厚度之關係 60
圖4-9 不同濺鍍時間下，AlN薄膜沈積在LiNbO3基板上之AFM 2D與3D照片；固定條件為濺鍍功率370W、腔室壓力15mTorr、氮氣濃度40﹪、基板溫度400℃ 61
圖4-10 不同濺鍍時間下，AlN薄膜沈積在ST-quartz基板上之AFM 2D與3D照片；固定條件為濺鍍功率370W、腔室壓力15mTorr、氮氣濃度30﹪、基板溫度400℃ 62
圖4-11 (a)AlN/LiNbO3結構中，沈積時間與表面粗糙度的關係(b)AlN/ST-quartz結構中，沈積時間與表面粗糙度的關係 63
圖4-12 IDTs電極照片，波長為35μm的單指叉 64
圖4-13 AlN/LiNbO3結構下，h/λ=0之頻率響應圖 65
圖4-14 AlN/LiNbO3結構下，h/λ=0.04之頻率響應圖 66
圖4-15 AlN/LiNbO3結構下，h/λ=0.09之頻率響應圖 67
圖4-16 AlN/LiNbO3結構下，h/λ對SAW元件中心頻率之關係 68
圖4-17 AlN/ST-quartz結構下，h/λ=0之頻率響應圖 69
圖4-18 AlN/ST-quartz結構下，h/λ=0.05之頻率響應圖 70
圖4-19 AlN/ST-quartz結構下，h/λ=0.13之頻率響應圖 71
圖4-20 AlN/ST-quartz結構下，h/λ對SAW元件中心頻率之關係 72
圖4-21 AlN/ST-quartz結構下，溫度對SAW元件中心頻率之關係 73
圖4-22 AlN/ST-quartz結構下，溫度對SAW元件中心頻率變化分率((f-f0)/f0)之關係 74
圖4-23 AlN/ST-quartz結構下，h/λ對TCF之關係 75
圖4-24 AlN/LiNbO3結構下，溫度對SAW元件中心頻率之關係 76
圖4-25 AlN/LiNbO3結構下，溫度對SAW元件中心頻率變化分率((f-f0)/f0)之關係 77
圖4-26 AlN/LiNbO3結構下，h/λ對TCF之關係……………78
表一 AlN材料的基本特性 79
表二 LiNbO3晶體的基本特性 80
表三 LiNbO3晶體在工業上的應用 81
表四 可用做表面聲波元件的材料 81
表五 反應性射頻磁控濺鍍系統沈積氮化鋁薄膜之系統參數 82
表六 JCPDS DATAS OF AlN POWDER 83
表六 JCPDS DATAS OF LiNbO3 POWDER 84
表七 IDTs電極設計之參數 85

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