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、高频和高温电子器件衬底材料，引起了人们的广泛关注。SiC的研究和开发主要集中在多型体4 H和6 H，这是由于它们作为单晶的可用性以及它们在高功率和高频器件中的应用。此外，立方相3C-SiC对于金属氧化物半导体场效应晶体管（MOSFET）的制造特别有吸引力。在这项研究中，3C-SiC单晶的微观结构表征已进行了透射电子显微镜（TEM），以澄清缺陷的形成机制，并制定减少缺陷。用聚焦离子束技术制备了用于TEM截面观察的样品，最近发展了一种新的技术来减少300μm厚的3C-SiC自支撑晶片上的平面缺陷，该技术去除了具有[110]和[-1-101]方向斜面的“波状Si”衬底。在3C-SiC/Si（001）界面附近观察到许多平面缺陷，它们被确定为堆垛层错和反转畴界。在Si/SiC界面附近2μm范围内存在微孪晶。层错密度随着SiC厚度的增加而减小。层错的减少似乎受到波状Si的影响。SiC衬底/SiC外延层界面附近和顶面附近的显微结构。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.