High Growth Rate of 4H-SiC Epilayers on On-Axis Substrates with Different Chlorinated Precursors

Abstract

The epitaxial growth of 4H-SiC on on-axis substrates is a very important process to meliorate in order to accelerate the development and improve the performance of bipolar SiC-based power devices, but until now, only relatively low growth rate processes have been achieved. The aim of this study is to demonstrate a high growth rate deposition process of high-quality 4H-SiC epilayers on on-axis substrates, free of 3C-SiC inclusions. Previous studies showed that silicon-rich gas-phase conditions, high Cl/Si ratios, or both were vital in order to avoid 3C-SiC inclusions in the epitaxial layers when grown on on-axis substrates. This study combines the knowledge of surface pretreatment with the chloride-based chemistry developed for off-axis growth. Two different precursor approaches were used, one adopting silane and ethylene with addition of hydrogen chloride and the other based on methyltrichlorosilane (MTS). In this study, we show that using a MTS-based chemical vapor deposition (CVD) process in combination with proper in situ silane etching and accurate optimization of the other process parameters results in homoepitaxial growth of high-purity and high-quality 4H-SiC layers on on-axis Si-face substrates at a growth rate of 100 μm/h. A higher efficiency of the MTS precursor chemistry was found and discussed.