雷射干涉重力波偵測站組織(Laser Interferometer Gravitational-Wave Observatory, LIGO)建立大型麥克森干涉儀進行重力波偵測為主要研究，其偵測器內的共振腔之高反射鏡為核心元件，由於重力波訊號容易受到各種雜訊干擾，所以在目前約100Hz的量測頻率下，可以得到最低的總體雜訊，但在此頻率範圍下，高反射鏡光學薄膜材料的熱擾動雜訊(Coating Brownian noise)為最嚴重的雜訊，而此雜訊的大小可以與材料機械損耗的正比關係來判斷。另外，用在光學系統的高反射鏡薄膜材料也必須擁有高品質的光學性質，因此致力於開發低機械損耗且高品質光學特性之薄膜材料為本實驗室的主要研究重心。
先前本實驗室已利用PECVD開發出不同成份比的氮化矽薄膜材料並研究出具備高折射係數、低的低溫機械損耗的SiN0.33H0.58，但薄膜的光學吸收依然偏高。此外，透過本實驗室先前研究發現，光學吸收與薄膜內的N-H鍵以及矽懸鍵有正相關性，因此為了降低氮化矽薄膜材料的光學吸收，本研究提出了低壓化學氣相沉積(LPCVD)的高溫製程方式，可以使薄膜內H含量大幅的減少，預期將薄膜內的N-H鍵下降， 改善光學吸收。本研究利用LPCVD鍍製氮化矽薄膜並藉由調整反應氣體SiH2Cl2與NH3的流量比例以調整薄膜之特性，分析不同流量比的氮化矽薄膜的成分組成，並找出光學吸收表現相對較佳的氮化矽薄膜。
本研究結果顯示，LPCVD鍍製的氮化矽薄膜其H含量相較PECVD明顯比較低，並隨著SiH2Cl2/ NH3流量比例上升，氮化矽薄膜材料內的N-H鍵濃度下降且很快地就進入偵測極限以下，並找到最低的光學吸收薄膜材料SiN0.91H0.02，相較於PECVD的所有氮化矽薄膜擁有更低的光學吸收。另外，從先前研究發現，氮化矽薄膜的低溫機械損耗與N-H鍵含量有正相關，因此筆者著手開發應用於LPCVD氮化矽薄膜機械損耗量測的silicon cantilever製程，預計用LPCVD所鍍製的氮化矽薄膜可以得到更低的低溫機械損耗結果。故可以被期待做為下世代低溫重力波探測儀的高反射鏡材料。

Laser Interferometer Gravitational-Wave Observatory (LIGO) is a group of scientists focused on detection of gravity wave signals by the large-scale Michelson interferometer and the high reflector QW coatings of the resonator cavity is the core equipment in the michelson interferometer. Gravity wave signals are easily interfered by various noises, and the Coating Brownian noise of high-reflective QW coatings is one of them. Through the fluctuation-dissipation theorem, the coating Brownian noise is directly related to the mechanical loss of the materials. In addition, the optical absorption of the coatings should be low. Therefore, the main mission of this thesis is develop materials with low optical absorption and low mechanical loss.
Previously, our laboratory has used PECVD to develop silicon nitride thin film with different composition ratios, which have high refractive index and low mechanical loss; however, slightly higher optical absorption. In addition, through the previous research of our laboratory, it was found that the optical absorption is proportional to the N-H bond and silicon dangling bond in the film. In order to reduce the optical absorption of the silicon nitride thin film, we propose a high-temperature process method of LPCVD, which can greatly reduce the H content in the film, thereby reducing the N-H bond in it to improve the optical absorption. Therefore, we tried a LPCVD process with optimal parameters (SiH2Cl2 and NH3 flow) and expecting that the N-H bond and hence the optical absorption could be reduced.
The experimental results showed that the H content of the silicon nitride film deposited by LPCVD is significantly lower than that of PECVD, and the SiH2Cl2/NH3 flow-rate ratio increased which led to the N-H bond concentration of the film decreased. In this study, the best LPCVD silicon nitride film, SiN0.91H0.02, showed lower optical absorption than any of the silicon nitride films of PECVD. In addition, it has been found from previous studies that the mechanical loss of silicon nitride films is proportional to the content of N-H bond in cryogenic temperature. Therefore, we set out to develop a silicon cantilever fabrication for the measurement of mechanical loss of LPCVD silicon nitride films. It is expected that the silicon nitride film deposited by LPCVD can obtain lower mechanical loss than PECVD in cryogenic temperature. The result of this thesis showed that the LPCVD silicon nitride film would out-perform the PECVD silicon nitride film, so it can expect to be used for the next-generation LIGO cryogenic gravitational wave detector.

Abstract i
摘要 iii
致謝 v
目錄 vii
圖目錄 ix
表目錄 xii
第一章、導論 1
1-1 前言 1
1-2 研究動機 3
第二章、 低壓化學氣相沉積(LPCVD)機台介紹 8
2-1 LPCVD之製程原理 8
2-2 LPCVD之機台介紹 8
2-2.1 LPCVD之機台操作 9
2-2.2 LPCVD之機台限制 14
第三章、石英基板鍍膜之相關載台設計 16
3-1 鐵氟龍載台結構設計與使用方式 16
3-2 石英基載台結構設計與使用方式 19
第四章、不同成分比之氮化矽薄膜材料組成分析 22
4-1 氮化矽薄膜製程流量調整介紹 22
4-2 氮化矽薄膜材料組成分析 24
4-2.1 薄膜材料之元素成分比例 24
4-2.2 薄膜材料之質量密度 26
4-2.3 薄膜材料之矽懸鍵密度 27
4-2.4 薄膜材料之鍵結密度與原子密度 29
第五章、不同成分比之氮化矽薄膜光學特性分析 35
5-1 薄膜之折射率與能隙分析 35
5-2 薄膜之光學吸收分析 37
5-2.1 PCI光學吸收量測及基本分析 37
5-2.2 1064 nm、1550 nm、1950 nm三個波長的光學吸收分析 38
第六章、LPCVD與PECVD之氮化矽薄膜特性比較 49
6-1 LPCVD與PECVD製程環境參數比較 49
6-2 氮化矽薄膜之組成特性比較 49
6-3 氮化矽薄膜之光學特性比較 51
第七章、單晶矽懸臂結構與製程設計 52
7-1 單晶矽懸臂結構 52
7-2 單晶矽懸臂製程設計 53
7-3 製程上遇到之困難與解決方案 60
7-3.1 乾蝕刻製程之過蝕刻現象 60
7-3.2 乾蝕刻製程之邊緣效應 61
第八章、總結與未來展望 63
8-1 總結 63
8-2 未來工作 66
8-2.1 完成單晶矽懸臂製程 66
8-2.2 量測室溫與低溫薄膜機械損耗 66
8-2.3 使用退火來降低氮化矽薄膜之光學吸收 66
參考文獻 67

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