以穿透式電子顯微鏡斷層掃描分析技術研究矽奈米線於電晶體元件的應用

Abstract

近年隨著奈米科技與半導體製程的快速發展，材料特徵尺寸的微縮，使得獲取材料三維形貌、成分和物理性質的需求提升，突顯了電子斷層掃描技術的重要性。在未來新一代可能的場效應電晶體中，矽奈米線電晶體的電性與其界面結構性質有著高度相關，這也使得對矽奈米線表面結構和截面形狀進一步了解的需求有所增加。在過去的十年中，重構運算方法的發展以及電腦計算速度的提高，使電子斷層掃描技術成為分析三維奈米材料資訊相當可靠的方法。此研究中，利用高角度環形暗場掃描穿透式電子斷層掃描技術，以聯立迭代重建法，三維重構氣-液-固機制磊晶成長之矽奈米線。此外，也利用電子斷層掃描重構技術，分析包覆化學氣相沉積成長之二硫化鉬薄層的矽奈米線結構。透過此研究，提供以穿透式電子顯微鏡斷層掃描分析技術，研究矽奈米線於電晶體元件的應用的可行性。

With recent advances in nanotechnology and semiconductor manufacturing, the decreasing feature sizes of devices highlight the need for electron tomography to explore the morphology, composition, and physical properties of device components in three dimensions. In next-generation field-effect transistors, the electronic properties of Si nanowire transistors highly depend on their interfacial structure. The demand of deeper knowledge about the surface structure and cross-sectional shape of Si nanowires has been increased; on this regard, the development of novel reconstruction algorithms and the increased computation speed in the last decade have improved electron tomography to be a reliable approach to 3D visualization for obtaining the analytical information. In this research, high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images with the simultaneous iterative reconstruction technique (SIRT) is used to reconstruct the 3D structure of Si nanowires which are epitaxially grown on Si(111) substrates using the vapor-liquid-solid (VLS) method by chemical vapor deposition (CVD). In addition, the Si nanowires coated with a thin molybdenum disulfide (MoS2) layer by CVD are also analyzed via the tomographic reconstruction method. The feasibility of epitaxial Si nanowires for the application of nanowire transistors is discussed based on the transmission electron tomography analysis.