High quality 4H-SiC homo-epitaxial wafer using the optimal C/Si ratio

Abstract

Epitaxial growth of 4H-SiC on 4° off-axis substrates has been performed under different C/Si ratio in order to improve the quality level of epitaxial layer. 4H-SiC homoepitaxial layer is grown in horizontal warm-wall planetary reactor. The growth rate, doping concentration, morphology defect of epitaxial layer are characterized using the Fourier transform infrared, Hg schottky contact and optical surface analyzer, respectively. Meanwhile, the epitaxial layer is etched by molten KOH and microscopy observation to understand conversion of BPDs dependence of C/Si ratio. It is suggested that the defect density in the epitaxial layer is increased under C-rich and Si-rich condition, since the increasing of 2D island nucleation and formation of silicon drops, respectively. Moreover, this low conversion ratio is considered to be induced by suppression lateral growth under the low C/Si ratio condition. As a result, epitaxial layer with high yield (99.7%) and extremely low basal plane dislocations density (＜0.05 cm−2) can be obtained by the optimization of C/Si ratio.