雷射干涉重力波偵測天文台(LIGO)利用大型麥克森干涉儀偵測重力波，由於重力波訊號相當微弱又容易受到各種雜訊干擾，所以必須降低環境雜訊以提高重力波探測系統的靈敏度。反射鏡薄膜材料的熱擾動雜訊為影響系統的雜訊來源之一，根據fluctuation-dissipation theorem得知此雜訊與材料之機械損耗成正比。此外做為光學應用之高反射鏡薄膜也必須擁有良好的光學性質，因此研發低機械損耗且光學特性良好之薄膜材料為本實驗室的主要研究方向。
先前本實驗室已利用PECVD開發出氮化矽薄膜材料SiN0.33H0.58，其具備高折射係數、低且平坦的低溫機械損耗，但薄膜的光學吸收偏高；而低折射係數材料目前只有研發出SiO2薄膜，SiO2的優點為具有低折射率與低光學吸收，但其缺點為過高的低溫機械損耗以及因Si-O-Si鍵之two-level system而具有機械損耗峰值，為了改善此問題我們提出將氮原子加入SiO2形成氮氧化矽的想法，預期減少Si-O鍵結以改善低溫機械損耗峰值。本研究使用PECVD鍍製氮氧化矽薄膜並透過改變反應氣體N2O與SiH4的流量比例以調整薄膜之特性，量測與分析不同流量比之氮氧化矽薄膜的成分組成、應力、楊氏係數、光學特性及機械損耗。
研究結果顯示，隨著N2O/SiH4流量比例降低，氮氧化矽薄膜材料內Si-N鍵濃度上升而Si-O鍵濃度減少其低溫機械損耗隨之下降，並且改善機械損耗峰值的大小，整體而言氮氧化矽材料之機械損耗皆低於二氧化矽，同時又保有低折射係數及低光學吸收之特性，因此我們透過Essential Macleod以氮氧化矽材料與SiN0.33H0.58設計出高反射鏡堆疊結構並評估其穿透率及光學吸收，接著計算此高反射鏡堆疊膜的熱雜訊理論值並與下世代重力波探測站規格比較，由結果得知氮化矽/氮氧化矽之高反射鏡堆疊膜的熱雜訊理論值與下世代重力波偵測站規格相近，更低於KAGAR規格1.5倍，因此可期待氮化矽/氮氧化矽堆疊膜應用於下世代LIGO重力波探測系統。

Laser Interferometer Gravitational-Wave Observatory (LIGO) uses the large Michelson interferometer to observe the gravitational wave directly. Due to the signal of the gravitational wave is quite weak and is impacted by various noise easily, it is important that increasing the sensitivity of the detector by reducing the environmental noise. The coating Brownian noise which is contributed from the materials coated on the high-refractive mirror is one of the noise types influencing the measuring systems. According to the fluctuation-dissipation theorem, the coating Brownian noise is proportional to the mechanical loss of the materials. Additionally, the coating materials of the high-refractive mirror must have excellent optical characteristics. Therefore, we have been dedicated to developing thin-film materials with low mechanical loss and outstanding optical properties.
Our research group developed NH3-free silicon nitride thin film, SiN0.33H0.58, which had a high refractive index and low cryogenic loss without loss peak; however, slightly higher optical absorption. On the other hand, the silica film has been only one low-index material that we have developed so far. The advantages of silica film are low refractive index and low optical absorption; however, the silica film has the higher cryogenic loss with the loss peak caused by the two-level systems of the Si-O-Si bond. To improve this problem, we came up with adding nitrogen atom in silica to form silicon oxynitride. We expected that the concentration of the Si-O bond in the film would decrease, and the cryogenic loss peak would be optimized. In this investigation, we used PECVD to fabricate the silicon oxynitride films and tuned the properties of films by varying N2O to SiH4 flow-rate ratio. Moreover, we measured the different silicon oxynitride films composition, stress, Young’s modulus, optical properties, and mechanical loss.
The experimental results showed that the N2O/SiH4 flow-rate ratio decreased which led to increasing the Si-N bond concentration in the films, declining the Si-O bond concentration, the cryogenic loss of film, and the loss peak. The silicon oxynitride films in this research not only had lower cryogenic loss than silica but also remained low-index and low absorption. Therefore, we used SiN0.33H0.58 and silicon oxynitride to design the high-refractive mirror structures by the simulation software Essential Macleod, meanwhile evaluating the transmittance and optical absorption of the HR mirror structures. The coating thermal noise of the HR mirror stack was also calculated and compared to the specification of the coating thermal noise of the mirrors applied in the next-generation gravitational wave detectors. The results showed that the theoretical coating thermal noise of the silicon nitride/silicon oxynitride HR mirror stack was close to the specification of ET-LF and LIGO Voyager. Besides, the theoretical value was approximately 1.5 times lower than the specification of KAGRA. Therefore, we expect that the silicon nitride/silicon oxynitride HR mirror stack will be used for the next-generation LIGO gravitational wave detection system.

Abstract i
摘要 iii
致謝 iv
目錄 v
圖目錄 vii
表目錄 x
第一章、導論 1
1-1 前言 1
1-2 研究動機 3
第二章、不同成分比之氮氧化矽薄膜材料組成分析 7
2-1 氮氧化矽薄膜製程介紹 7
2-2 氮氧化矽薄膜材料成分分析 10
2-2.1 薄膜材料之元素成分比例 10
2-2.2 薄膜材料之質量密度 12
2-2.3 薄膜材料之懸鍵密度 13
2-2.4 薄膜材料之鍵結密度與原子密度 15
第三章、不同成分比之氮氧化矽薄膜基本特性分析 23
3-1 薄膜材料之折射係數與能隙分析 23
3-2 薄膜材料之應力分析 26
3-3 薄膜材料之楊氏係數分析 28
第四章、不同成分比之氮氧化矽薄膜光學吸收分析 30
4-1 光學吸收量測基本原理與架構 30
4-2 薄膜材料之光學吸收 32
第五章、不同成分比之氮氧化矽薄膜之機械特性 38
5-1 機械損耗量測系統之原理與架構 38
5-1.1 單晶矽懸臂基板製程 38
5-1.2 機械損耗基本原理 41
5-1.3 機械損耗量測系統架構 43
5-2 不同成分比之氮氧化矽薄膜低溫機械損耗 45
5-3 不同成分比之氮氧化矽薄膜室溫機械損耗 52
第六章、四分之一波長厚度之氮化矽與氮氧化矽堆疊 55
6-1 氮化矽與氮氧化矽薄膜堆疊光學模擬與相關參數計算 57
6-2 利用氮化矽與氮氧化矽之機械損耗量測值計算堆疊膜機械損耗理論值 59
6-3 氮化矽與氮氧化矽堆疊膜之bulk與shear機械損耗及CTN計算 60
第七章、總結與未來工作 64
7-1 總結 64
7-2 未來工作 67
參考文獻 68

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