矽鍺薄膜高溫氧化處理與奈米機械特性之研究

Abstract

本論文針對矽鍺/矽之異質接面結構以虛擬基板(virtual substrate)方式做應用，探討其高溫氧化熱處理後矽鍺薄膜之材料特性以及機械特性。首先，利用超高真空化學氣相沈積矽鍺薄膜在矽基材上，接著進行高溫(800 °C-1000 °C)氧化熱處理；並以化學分析電子儀、二次離子質譜儀、X光散射分析儀以及原子力顯微鏡等分析儀器做材料分析。最後用奈米壓痕機測試薄膜之機械強度。當壓痕深度小於50 nm時，由於高溫氧化處理後之薄膜表面有鍺原子堆積以及較大之應變鬆弛之影響，故與未氧化處理之表面相較起來，其機械強度有下降低之趨勢。然而在壓痕深度於100至200 nm時，因高溫氧化下應變鬆弛所導致錯位差排之現象，造成機械強度上升。綜合材料分析與機械分析可以得知，此矽鍺薄膜可確實經由高溫氧化處理後形成一理想之虛擬機材。本論文研究結果期待可供未來矽鍺/矽虛擬基板在高溫氧化技術及機械可靠度上之應用參考。

The purpose of this study was to investigate the effect of high-temperature oxidation on the material and mechanical properties of SiGe/Si heterostructures which can serve as virtual substrates. A homogeneous SiGe epilayer was deposited by ultrahigh vacuum-chemical vapor deposition (UHV/CVD) both with and without high-temperature oxidation treatments. Electron spectroscopy for chemical analysis (ESCA), secondary ion mass spectroscopy (SIMS), atomic force microscopy (AFM) and X-ray diffraction (XRD) analysis were conducted. The mechanical properties of SiGe thin film were determined using nanoindentation. Mechanical properties of SiGe thin films were degraded after high temperature oxidation treatment followed by indentation depths of less than 50 nm due to the Ge pile-up and stain relaxation on the surface. However, high temperature oxidation treatments also lead to strain relaxation in the form of misfit dislocations, which can increase the hardness and modulus with indentation depths between 100 and 200 nm. Therefore, SiGe thin film can be treated as an ideal virtual substrate after appropriate high-temperature oxidation treatments.