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通过光学显微镜和表面缺陷检测仪对4H-SiC外延晶片表面三角型缺陷进行观测和分析,发现三角型缺陷大致可以分为两类:头部无任何异物的三角型缺陷和头部带有异物的三角型缺陷。通过理论分析认为:头部无异物缺陷主要是由于缓冲层和外延层的生长条件不同引起的;头部有异物缺陷主要是由于衬底玷污和生长过程中的掉落物引起的。在此基础上针对两种不同缺陷分别提出了相应外延优化工艺:缓冲层优化工艺和生长前衬底刻蚀优化工艺。实验结果显示,这两种优化工艺有效降低了三角型缺陷的数量,提高了外延晶片质量。
Observation and analysis of triangular defects on the surface of 4H-SiC epitaxial wafers by optical microscope and surface defect detector found that triangular defects can be divided into two categories: triangular defect with no foreign body in head and foreign body with foreign body in head Triangular defects. Through theoretical analysis, it is concluded that there are no foreign body defects in the head due to the different growth conditions of the buffer layer and the epitaxial layer. The foreign body head defects are mainly caused by the substrate tarnishing and the falling objects in the growth process. On this basis, corresponding epitaxial optimization processes are proposed for two different defects respectively: the buffer layer optimization process and the pre-growth substrate etching optimization process. The experimental results show that the two optimization processes effectively reduce the number of triangular defects and improve the quality of epitaxial wafers.