在半導體的製程中，界面應變(Interfacial strain)是改變元件特性的關鍵，因此，本實驗主要運用X光三光布拉格表面繞射(X-ray Three-Beam Bragg-Surface Diffraction，BSD)實驗方法，以入射X光同時激發矽(Si)基板與矽鍺(SiGe)薄膜之繞射光，藉由收取的矽基板與矽鍺薄膜之二階繞射光來分析界面應變，以便更清楚了解元件的特性。
本實驗所使用的入射X光能量為12KeV，於國家同步輻射研究中心(National Synchrotron Radiation Research Center，NSRRC)光速線BL17B1來進行實驗。首先進行掠角繞射與布拉格繞射來研究SiGe/Si樣品的晶體品質；再來進行三光布拉格表面繞射實驗來研究SiGe/Si在不同薄膜厚度的界面應變。此處三光分別代表入射光、一階繞射光與二階繞射光，而二階繞射光波向量會沿著晶體表面行進，故又稱為二階表面繞射光。
實驗使用的樣品為SiGe薄膜成長於[0 0 1]方向的六吋Si基板上，薄膜矽鍺比例為Si0.8Ge0.2。此樣品是委託國家奈米實驗室 (NDL) 使用分子磊晶(MBE)製程製作，SiGe薄膜厚度為59.90、47.58、28.72、23.23nm。實驗分析結果發現，薄膜厚度較厚時，薄膜垂直晶軸的應變較大，且薄膜厚度與應變大小存在一線性關係y = 0.012x + 0.9986，其中x為薄膜厚度、y為應變。因此可推測當薄膜厚度越厚，它的彈性應變能也會增大，在到達薄膜臨界厚度h_c之前，薄膜垂直晶軸的應變也會越大。

ABSTRACT
Study of Probing Interfacial Strains in SiGe/Si
Using Three-Beam Bragg-Surface Diffraction
Ting-Wei Wu, Advisor : Professor Shih-Lin Chang
Master of Physics,
National Tsing Hua University, Hsin-Chu, Taiwan

In the manufacturing process of semiconductor, interface strains play an important role in changing the device characteristics. In order to understand more clearly the characteristics of the device, we study of probing interfacial strains in SiGe/Si sample using Three-Beam Bragg-Surface Diffraction(BSD).
The experiment was performed on BL17B1 beam line in the National Synchrotron Radiation Research Center(NSRRC). The energy of incident X-rays used is 12KeV. First of all, we study crystalline quality of SiGe / Si samples using grazing incidence X-ray diffraction and Bragg’s diffraction. Afterwards, we study interfacial strains of SiGe / Si samples at different thickness of film using Three-Beam Bragg-Surface Diffraction(BSD).
The sample is a germanium silicide film grown on a silicon substrate, where the SiGe film is about 59.90、47.58、28.72、23.23nm thick, which was manufactured by National Nano Device Laboratory(NDL). The experimental analysis found that when the thickness of the germanium silicide film becomes thicker and before reaching the critical thickness of film, the interfacial strains along the c-axis gets strong.

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