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平面六方空洞是SiC晶体中一种典型的体缺陷,其存在严重影响了晶片的质量。因此,研究和去除平面六方空洞缺陷对提高晶片质量有重要意义。使用物理气相输运法(physical vapor transport,PVT)制备了4块6H-SiC单晶,使用光学显微镜观察了平面六方空洞的分布和形貌特征,并研究其形成机制。结果表明,平面六方空洞的形成主要由籽晶背向分解造成的。籽晶背向分解存在两个必要条件:籽晶背面存在与其相接触的气孔;气孔内与籽晶背面相接触的区域比其他区域温度高。籽晶背面的TaC致密膜层能够抑制籽晶背面的分解。结合使用在籽晶背面生成致密TaC膜层和粘结固定两种措施,有效地抑制了籽晶的背面分解,得到了无平面六方空洞缺陷的SiC晶体。
Plane six-hole is a typical body defects in SiC crystal, its existence has seriously affected the quality of the wafer. Therefore, it is of great significance to study and remove the planar hexagonal cavity defects to improve the quality of the wafer. Four 6H-SiC single crystals were prepared by physical vapor transport (PVT). The distribution and morphology of hexagonal cavities were observed by light microscopy. The formation mechanism was also studied. The results show that the formation of planar hexagonal cavities is mainly caused by the backscattering of seeds. There are two necessary conditions for the back-decomposition of the seed crystal: there are pores on the back surface of the seed crystal which contact with the seed crystal; those in the stoma which contact with the back surface of the seed crystal have a higher temperature than other areas. The TaC dense film on the back of the seed can inhibit the decomposition of the seed back. The combination of using dense TaC film on the backside of the seed crystal and bonding and fixing two methods can effectively restrain the backside decomposition of the seed crystal and obtain the SiC crystal without any planar hexagonal cavity defect.