雷射干涉重力波天文台(Laser Interferometer Gravitational-Wave Observatory, LIGO)利用大型麥克森干涉儀來觀測重力波，由於重力波訊號非常微弱，所以降低探測儀的雜訊以提高靈敏度是目前主要的研究。高反射鏡的薄膜熱擾動雜訊(Coating Brownian noise)為主要雜訊之一，但其不易量測，於是可藉由量測與其成正比的機械損耗來判斷。而LIGO的大型麥克森干涉儀所使用高反射鏡除了要有低的機械損耗外，還必須要有極低的光學吸收，材料光學吸收的好壞將嚴重影響高反射鏡的品質。因此本實驗室的研究分別注重於低機械損耗和低光學吸收的薄膜材料上。
本研究首先更改了鍍製氮氧化矽薄膜中的靶材、冷卻水水溫及離子源參數，主要的目的是為了改善先前氮氧化矽薄膜中但含量過少及金屬汙染物過高的問題。經過將靶材由二氧化矽靶更改為矽靶及降低冷卻水水溫後，確實有效的改善了上述的問題，但隨之而來的影響卻是矽懸鍵數量的增加，且原先薄膜中含有氫元素的問題仍還存在於新製程的薄膜中，於是我們將目光轉向使用基板加熱系統來改善氫含量和矽懸鍵的問題。
加裝了基板加熱系統後，我們嘗試了鍍製不同基板溫度下，相同製程參數的氮氧化矽薄膜，並對薄膜進行一連串的測量。經由測量後發現隨著基板溫度的升高，薄膜中的氮含量漸漸增加，而氧含量緩緩減少，除此之外薄膜中的氫含量和矽懸鍵數量皆有減少的趨勢，進而使消光係數降低，達到了當初加裝基板加熱系統所追求的結果。然而薄膜的消光係數仍在10-5數量級上下，無法再將其降低，主要的原因在於矽懸鍵及能隙對消光係數的影響。
日後可嘗試進行補氫退火再度減少薄膜中的矽懸鍵，以降低其消光係數，又或者可將薄膜進行低溫的機械損耗量測，觀察與其他薄膜的機械損耗差異。

The Laser Interferometer Gravitational-Wave Observatory (LIGO) uses a large Michelson interferometer to observe gravitational waves. Since gravitational wave signals are extremely weak, reducing the noise of the detector to improve sensitivity is the main topic of this research. The Coating Brownian noise of a high-reflecting mirror is one of the main noises. However, it is difficult to measure the noise directly, to that end, we measure mechanical loss, which is proportional to the noise. In addition to low mechanical loss, the high-reflection mirrors used in LIGO’s large Michelson interferometer must have extremely low optical absorption. The quality of the material’s optical absorption will severely affect the quality of the high-reflection mirrors. Therefore, the research in this laboratory focuses on low mechanical loss of thin film materials and low optical absorption.
First we changed the target material, cooling water temperature and ion source parameters for the coating process of the silicon oxynitride film. The main purpose of these adjustments is to improve the problem of too little nitrogen and too much metal contaminants in the silicon oxynitride film. By changing the target material from silicon dioxide to silicon and lowering the temperature of the cooling water, the aforementioned problems can be effectively solved. Nevertheless, the number of silicon dangling bonds increases consequently, and the existence of hydrogen remains a problem in the films of proposed process. As a result, we turned our attention to the use of substrate heating systems to reduce the hydrogen content and the number of silicon dangling bonds.
After installing the substrate heating system, we coated the silicon oxynitride films with identical parameters at different substrate temperatures ,and performed a series of measurements on the films. We found that as the substrate temperature rises, the nitrogen content in the film increases, while the oxygen content decreases. In addition, the hydrogen content and silicon dangling bonds in the films tends to decrease with the increasing substrate temperature, thereby decreasing the extinction coefficient, which matches our initial purpose for installing the substrate system.
In the future, we hope to attempt employing hydrogen annealing to further reduce the number of silicon dangling bonds in the film, to further reduce the extinction coefficient, or measure the mechanical loss of the films to observe the difference in mechanical loss compared to other films.

[1] A. Einstein, Albert. Besprechung von" A. Einstein: Die Grundlage der allgemeinen Relativitätstheorie". NW, 1916, 4: 481.
[2] ABBOTT, Benjamin P., et al. Observation of gravitational waves from a binary black hole merger. Physical review letters, 2016, 116.6: 061102.
[3] COLLABORATION, LIGO SCIENTIFIC. Instrument Science White Paper 2018. 2018.
[4] CALLEN, Herbert B.; WELTON, Theodore A. Irreversibility and generalized noise. Physical Review, 1951, 83.1: 34.
[5] GREENE, Richard F.; CALLEN, Herbert B. On the formalism of thermodynamic fluctuation theory. Physical Review, 1951, 83.6: 1231.
[6] CALLEN, Herbert B.; GREENE, Richard F. On a theorem of irreversible thermodynamics. Physical Review, 1952, 86.5: 702.
[7] 蔡文杰, “以電漿輔助化學沉積法鍍製氮氧化矽薄膜其光學特另與機械特性之探討” , 國立清華大學碩士論文 (2020)
[8] 黃榛莉, “電漿輔助化學氣相沉積之氮化矽薄膜其熱退火後光學特性與無氨氣電漿輔助化學氣相沉積法之氮化矽薄膜其光學及機械特性之探討” , 國立清華大學碩士論文 (2019)
[9] 陳俊廷, “以離子束濺鍍法鍍製氮氧化矽薄膜探討其光學特性” , 國立清大學碩士論文 (2020)
[10] SCHNEIDER, Jochen M., et al. On the effect of hydrogen incorporation in strontium titanate layers grown by high vacuum magnetron sputtering. Applied physics letters, 1999, 75.22: 3476-3478.
[11] 劉冠廷, “以離子束濺鍍法鍍製氮化矽薄膜其光學特性之探討” , 國立清大學碩士論文 (2020)

[12] 詹啟澔, “利用離子束濺鍍法及基板加熱系統鍍製氮化矽薄膜及其材料特性” , 國立清大學碩士論文 (2021)
[13] 黃文正, “以離子束濺鍍法製作低損耗薄膜應用於雷射干涉重力波偵測儀之高反射鏡製程準備”, 國立清華大學碩士論文 (2012)
[14] 王順錦, “應用於雷射干涉重力波偵測器以離子束濺鍍法製作之奈米膜層結構高反射鏡及其結晶條件之探討”, 國立清華大學碩士論文 (2013)
[15] F. Ay and A. Aydinli, “Comparative investigation of hydrogen bonding in silicon based PECVD grown dielectrics for optical waveguides,” Optical Materials. 26, 33–46 (2004).
[16] J. Dupuis, E. Fourmond, J. Lelièvre, D. Ballutaud, and M. Lemiti, “Impact of PECVD SiON stoichiometry and post-annealing on the silicon surface passivation,” Thin Solid Films. 516, 6954–6958 (2008)
[17] L. He, T. Inokuma, Y. Kurata, and S. Hasegawa, “Vibrational properties of SiO and SiH in amorphous SiOx:H films (0 ≤ x ≤ 2.0) prepared by plasma-enhanced chemical vapor deposition,” Journal of Non-Crystalline Solids. 185, 249–261 (1995)
[18] W. Scopel, M. Fantini, M. Alayo, and I. Pereyra, “Local structure and bonds of amorphous silicon oxynitride thin films,” Thin Solid Films. 413, 59–64 (2002).
[19] X. Tan, J. Wojcik, and P. Mascher, “Study of the optical properties of SiOxNy thin films by effective medium theories,” Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. 22, 1115–1119 (2004)
[20] Y. Wang, X. Cheng, Z. Lin, C. Zhang, and F. Zhang, “Optimization of PECVD silicon oxynitride films for anti-reflection coating,” Vacuum. 72, 345–349 (2003)
[21] B. Hallam, B. Tjahjono, and S. Wenham, “Effect of PECVD silicon oxynitride film composition on the surface passivation of silicon wafers,” Solar Energy Materials and Solar Cells. 96, 173–179 (2012)
[22] 張臨安, “以電漿輔助化學氣相沉積法鍍製高氮氮化矽薄膜其熱退火對光學特性與機械特性之影響”, 國立清華大學碩士論文 (2018)
[23] 康乃中, “光熱共光路干涉儀系統之設置與電漿輔助化學氣象沉積法沉積之氮化矽薄膜光學吸收研究”, 國立清華大學碩士論文 (2013)
[24] 蔡東霖, “以低壓化學氣相沉積法鍍製之氮化矽薄膜在雷射重力波偵測器反射鏡應用之研究”,國立清大學碩士論文 (2021)
[25] 桂芳成, “利用電漿輔助化學氣相沉積法鍍製氮化矽與氮氧化矽薄膜建構光學吸收經驗公式”,國立清華大學碩士論文 (2021)
[26] Vitkavage, D. J., and T. M. Mayer. "Target contamination by cathode sputtering in broad beam ion sources." Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 6.1 (1988): 154-155.
[27] Effect of elevated substrate temperature on growth,properties, and structure of indium tin oxide films prepared by reactive magnetron sputtering
[28] Roth, Alexander. Vacuum technology. Elsevier, 2012.
[29] H. C. Chen, Annealing effect on the room temperature mechanical loss of the silicon nitride films deposited with PECVD on silicon cantilever, Master thesis, NTHU, R.O.C. (2017)
[30] Chiang, Donyau, et al. "Determination of the Refractive Index of Molybdenum Using a Spectrophotometric Method." Sensors and Materials 31.11 (2019): 3517-3526.
[31] Sian, Tarsame S., and G. B. Reddy. "Optical, structural and photoelectron spectroscopic studies on amorphous and crystalline molybdenum oxide thin films." Solar energy materials and solar cells 82.3 (2004): 375-386.
[32] Yamada, Itsunari, et al. "Near-infrared polarizer with tungsten silicide wire grids." Japanese Journal of Applied Physics 50.1R (2011): 012502
[33] Hutchins, M. G., et al. "Preparation and properties of electrochemically deposited tungsten oxide films." physica status solidi (a) 176.2 (1999): 991-1002.
[34] 高煜勛, “降低以電漿輔助化學氣相沉積法鍍製之氮氧化矽薄膜光學吸收之研究”, 國立清華大學碩士論文 (2021)