本實驗室參與重力波觀測組織 (LIGO, Laser Interferometer Gravitational wave Observatory) 的研究計畫，其利用大型麥克森干涉儀量測重力波訊號，由於重力波訊號相當微弱，難以偵測，因此量測時必須盡可能減少額外雜訊。由雜訊頻譜中可知，在 40-400Hz 左右，雜訊來源主要為薄膜熱擾動 coating Brownian noise，此雜訊為薄膜產生且難以直接量測得到，但經由 fluctuation dissipation theorem 可知該雜訊與薄膜本身之機械損耗成正比關係，因此透過量測高反射鏡薄膜機械損耗去探討薄膜熱擾動為本實驗主要研究重點。
先前本實驗室利用 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；低折射係數方面，開發出透過 N 原子取代 O 原子來抑制因Si-O-Si鍵之two-level system造成的低溫機械損耗峰值，形成不同於 SiO2 非晶結構的氮氧化矽 SiO0.85N0.27H0.45(ratio3) 薄膜，不僅改善了 SiO2 的低溫機械損耗峰值問題，還保有低折射率、低光學吸收的特性。因此選用SiN0.33H0.58 與 SiO0.85N0.27H0.45(ratio3) 作為重力波高反射鏡薄膜材料。
本研究前半部分探討四分之一 1550nm 波長 SiON(ratio3)/SiN0.33堆疊膜之室溫機械損耗。1-pair、2-pair 及 4-pair 堆疊膜損耗量測結果相近，表示 SiON(ratio3)/SiN0.33 介面對機械損耗影響不大。頻率於 100Hz 之機械損耗約為10-5 order，此結果低於目前室溫重力波探測器 aLIGO 所使用的高反射鏡材料 TiO2-doped Ta2O5/SiO2 約下降了 2 倍。後半部分透過光學模擬軟體 Essential Macleod 設計氮氧化矽/氮化矽堆疊高反射鏡的堆疊結構並評估其光學穿透與吸收，再透過 Bulk and shear loss angle 評估氮氧化矽/氮化矽堆疊高反射鏡結構的熱雜訊(coating thermal noise)，將這些評估結果與重力波偵測器規格做比較，結果說明氮氧化矽/氮化矽堆疊高反射鏡結構的熱雜訊低於現今室溫重力波偵測器 aLIGO 反射鏡規格約 1.5 倍。

Our laboratory has participated in the research project of the Laser Interferometer Gravitational Wave Observatory(LIGO), which detects the gravity wave signal by large Michelson interferometer. Due to that the signal of gravitational wave is extremely weak and difficult to detect, it’s necessary to reduce the another noise during measurement. According to the noise spectrum, the sensitivity of interferometer is mostly limited by coating Brownian noise at 40-400Hz. The noise is generated by the thin film and is difficult to directly measure. The coating Brownian noise, which is proportional to mechanical loss stated by fluctuation-dissipation theorem. Therefore, the main research focus is to investigate the thermal noise of the film by measuring the mechanical loss.
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. In terms of low refractive index, we have developed the use of N atoms to replace O atoms to suppress the cryogenic loss peak caused by the two-level system of Si-O-Si bonds, forming silicon oxynitride SiO0.85N0.27H0.45 which is different from the amorphous SiO2 structure. Silicon oxynitride not only improves the cryogenic loss peak problem of SiO2, but also still have low refractive index and low optical absorption characteristic. Therefore, SiN0.33H0.58 and SiO0.85N0.27H0.45(ratio3) are selected as the materials for high reflection mirror coating.
The first half of this study is that discusses the room-temperature mechanical loss of SiON(ratio3)/SiN0.33 quarter-wave (QW) stacks. The mechanical loss results of 1-, 2- and 4-pair stacked samples are similar, indicating that the SiON(ratio3)/SiN0.33 interface has little effect on the mechanical loss. The loss is in 10-5 order at 100 Hz, this result is lower than the mirror coating TiO2-doped Ta2O5/SiO2 used in aLIGO about 2.2 times lower. The second half of this study is the optical simulation software Essential Macleod were used for designing the HR mirror structures of the silicon oxynitride/silicon nitride evaluate its optical transmission and absorption. The bulk and shear loss angle were used to evaluate the thermal noise of the silicon oxynitride/silicon nitride stacked structure. These results are compared with the specifications of the gravitational wave detectors and it showed that the thermal noise of the silicon oxynitride/silicon nitride stacked structure is about 1.5 times lower than the aLIGO specification of room temperature gravitational wave detector.

目錄
Abstract II
摘要 IV
致謝 V
目錄 VII
圖目錄 IX
表目錄 XI
第一章 導論 1
1-1 引言 1
1-2 動機 3
第二章 氮氧化矽與氮化矽堆疊膜製作 6
2-1矽懸臂基板製程與共振模態 6
2-2堆疊膜薄膜材料：SiON(ratio3)、SiN0.33 9
2-3 SiON(ratio3)/SiN0.33 堆疊膜製程 12
第三章 氮氧化矽與氮化矽堆疊膜之機械損耗 18
3-1 機械損耗原理與量測系統 18
3-1.1 機械損耗原理 18
3-1.2 室溫機械損耗量測系統介紹 19
3-1.3 低溫機械損耗量測系統介紹 21
3-2 氮氧化矽與氮化矽堆疊膜之室溫機械損耗 24
3-2.1 以 SiON(ratio3) 及 SiN0.33 之機械損耗計算堆疊膜機械損耗理論值 24
3-2.2 1-pair、2-pair 與 4-pair 之 SiON(ratio3)/SiN0.33 堆疊膜機械損耗量測結果與分析 27
第四章 氮氧化矽與氮化矽高反射鏡堆疊膜之 thermal noise 33
4-1 Thermal noise 公式介紹 33
4-2 SiON(ratio3)/SiN0.33 堆疊之 bulk 與 shear 機械損耗 34
4-2.1 Bulk 與 shear 能量比 34
4-2.2 Bulk 與 shear 機械損耗 36
4-3 SiON(ratio3)/SiN0.33高反射鏡堆疊膜之 thermal noise 39
4-3.1 SiON(ratio3)/SiN0.33 高反射鏡堆疊結構 39
4-3.2 Thermal noise 估算結果 41
第五章 總結與未來工作 43
5-1 總結 43
5-2 未來工作 44
附錄A 試片各層SiON(ratio3)、SiN0.33之薄膜厚度 47
附錄B 室溫量測系統夾具問題與改善方法 49
附錄C COMSOL 模擬 SiON(ratio3)/SiN0.33 堆疊膜能量比之流程 51
附錄D Essential Macleod 之高反射鏡模擬 62
參考文獻 66

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