Defect structure analysis and recluction of defects in SiC single aystal substrate

碳化硅（SiC）作为一种非常有用的大功率、高频、高温电子器件的衬底材料而备受关注。SiC的研究和发展主要集中在4H和6H多晶上，因为它们可以作为单晶使用，并且在大功率和高频器件中有广泛的应用。此外，立方型3C-SiC对于金属氧化物半导体场效应晶体管（MOSFET）的制造尤其具有吸引力。本研究利用透射电子显微镜（TEM）对3C-SiC单晶进行了微观结构表征，以阐明缺陷形成的机理，并对缺陷的减少进行研究。用聚焦离子束技术制备了TEM横截面观察用的试样。最近，在去除具有[110]和[-1-101方向倾斜的“起伏si”衬底后，在~ 300μm厚的独立型c - sic晶圆上开发了一种减少平面缺陷的新技术。在3C-SiC/Si（001）界面附近观察到许多平面缺陷，这些缺陷被识别为层错和反转畴边界。在Si/SiC界面2μm范围内存在微孪晶。随着SiC厚度的增加，层错密度逐渐减小。波状硅的作用似乎影响了层错的减少。靠近SiC衬底/SiC外延层界面和靠近顶表面的微观结构。在外延层中观察到许多层错。

Silicon carbide (SiC) has attracted much attention for a very useful substrate material of high power, high frequency and high temperature electronic devices. Research and development of the SiC focus mainly on the polytypes 4H and 6H due to their availability as single crystals and their applications in high power and high frequency devices. Furthermore the cubic 3C-SiC is especially attractive for the fabrication of metal-oxide-semiconductor field effect transistors (MOSFET). In this study, microstructural characterizations of the 3C-SiC single crystals have been carried out by transmission electron microscopy (TEM) to clarify the mechanism of formation of defects and to develop the reduction of defects. Specimens for TEM cross-sectional observation have been fabricated using a focused ion beam technique.Recently a new technique to reduce planar defects has been developed in〜300μm thick free-standing 3C-SiC wafers after removing an "undulant-Si" substrate with slopes oriented in the [110] and [-1-101 directions. Many planar defects are observed near the 3C-SiC/Si(001) interface, and those are identified to be stacking faults and inversion domain boundaries. Micro twins present within 2μm from Si/SiC interface. The density of stacking faults is observed to decrease as the SiC thickness increases. Reduction of stacking faults seems to be affected by the effect of undulant-Si. Microstructure near SiC substrate/SiC epitaxtial layer interface and also near the top surface. Many stacking faults were observed in the epitaxtial layer.