光學薄膜應力與熱膨脹係數量測之研究

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/6595

Title:	光學薄膜應力與熱膨脹係數量測之研究
Authors:	田春林;Shun-Lin Tian
Contributors:	光電科學研究所
Keywords:	相位偏移干涉術;熱膨脹係數;應力;薄膜;金屬氧化膜;thermal expansion coefficient;stress;optical thin films;phase shifting interferometry;metal oxide films
Date:	2000-06-21
Issue Date:	2009-09-22 10:23:32 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本論文提出一種創新的薄膜應力與熱膨脹係數的量測方法，此方法結合相位偏移干涉術及五步相位還原法，利用一種單面拋光的玻璃圓片為基板。基於光學干涉原理將干涉圖轉換為相位圖後，可獲致基板面形的偏移量，此法可精確測定基板在鍍膜前後的面形變化量，據此計算薄膜的平均應力值。此外，利用Zernike多項式擬合法，可得鍍膜前及鍍膜後基板的三維表面輪廓圖，扣除人為誤差項之後可得實際膜面的三維表面輪廓圖及二維應力分佈圖，並可判定薄膜沈積後的應力型態，有助於改善鍍膜品質。本文所提出的方法比其它的量測技術更為簡單、便捷且更為精確。為研究光學薄膜的力學性質，以離子束濺鍍法製鍍五種金屬氧化膜，應用相移干涉術可同時測定薄膜的熱膨脹係數及彈性模量，利用BK-7和Pyrex兩種材質的玻璃基板，已知其熱膨脹係數、楊氏係數及帕松比，測量金屬氧化膜的應力對溫度變化之關係。將薄膜樣品從室溫加熱至70°C，可分別測得金屬氧化膜同時沈積在BK-7和Pyrex基板的內應力對量測溫度之關係圖，以最小平方法進行線性擬合，從兩直線的斜率即可求得熱膨脹係數和彈性模量。在光學薄膜應力檢測的實驗中，分別探討各種氧化膜的應力行為，最後並建立薄膜應力及熱膨脹係數的資料庫，以提供製鍍光纖通訊用之次奈米窄帶干涉濾光片最佳製程參數。本論文已成功地研發一套薄膜應力與熱膨脹係數量測系統，其優點為高靈敏度、高精度、操作簡便且重現性高。尤其是系統擴充為控制溫度變化可應用於熱膨脹係數及彈性膜量之測定，在光學薄膜力學性質的研究上極為有用。This dissertation presents an original method for the measurement of the stress and the thermal expansion coefficient of optical thin films. The measuring method based on the phase shifting interferometry technique and five-step phase reduction algorithm. A circular disk polished on one side was used as the coated substrate during film deposition. The average stress in thin films can be derived by comparing the deflection of the substrate before and after film deposition. The deflection of the substrate by the deposited film was obtained by the phase map. Wavefront aberrations from tilt and defocus should be removed by fitting the Zernike polynomials. Using the Zernike polynomial fitting algorithm, a three-dimensional contour map and two-dimensional stress distribution were generated from the polynomial coefficients to visualize the deformation of the thin film and to examine the tensile or compressive stress after film deposition. The proposed method can facilitate the development of processes that yield more uniform films. Compared with other techniques, the present method is relatively simple, convenient and more accurate. To investigate the mechanical properties of metal oxide films, five oxide films were prepared by ion-beam sputter deposition (IBSD). This dissertation also reports on the application of the phase shifting interferometry technique for the concurrent measurement of the thermal expansion coefficient and the elastic modulus of optical thin films. The stresses in metal oxide films were measured with the phase shifting interferometry technique using two types of circular disks with known thermal expansion coefficients, Young’s moduli and Poission’s ratios. The temperature-dependent stress behavior of metal oxide films was obtained by heating samples in the range from room temperature to 70 °C. The internal stresses of optical thin films deposited on the BK-7 and Pyrex glass substrates were plotted against the stress measurement temperature, showing a linear dependence. The slope of the line for the difference data was determined by least squares fitting. From the slopes of the two lines in the stress versus temperature plot, the intrinsic stress, the thermal expansion coefficient and the elastic modulus of thin oxide films are then determined. The experiment results of the stress behavior in metal oxide films were given. Finally, the database of the stress and the thermal expansion coefficient of optical thin films were established. It can provide the optimum deposition parameters to manufacture subnanometer bandwidth interference filters used for fiber-optic communication. A novel measurement system for determining stress and thermal expansion coefficient of optical thin films has been successfully developed and constructed. It has the advantages of inherently high sensitivity, accuracy, easy operation and reproducible performance. In particular, it can be extended to varying-temperature applications and very useful in determining the mechanical properties of optical thin films.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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