Effect of additional Silane on in-situ H_2 etching prior to 4H-SiC homoepitaxial growth

摘要

We have investigated the influence of in-situ H_2 etching on the surface morphology of the 4H-SiC substrate prior to homoepitaxial growth. In this study, we varied the types of gas atmosphere during in-situ H_2 etching; namely, hydrogen (H_2) alone, hydrogen-propane (H_2+C_3H_8), and hydrogen-silane (H_2+SiH_4). We found that in-situ H_2 etching using H_2 + SiH_4 significantly improved the surface morphology of 4H-SiC substrate just after in-situ H_2 etching. By adding Si_4, formation of bunched step structure during in-situ H_2 etching could be significantly suppressed. In addition, H_2 etching using H_2 + SiH_4 was able to remove scratches by etching a thinner layer than that using H_2 alone. We also discussed the in-situ H_2 etching mechanism under the additional SiH_4 condition.