Etch rates for Si-face 4H-SiC using H2 and a C3H8 partial pressure
In an effort to calibrate nitrogen incorporation into the growing layer, a nitrogen step-doped sample was grown. In an attempt to reduce or eliminate incidental etching during pre- and post- growth temperature ramps, additional samples were etched under different propane partial pressures. With increasing propane partial pressure the etch rate decreases.
Effect of Additional Silane on In Situ H2 Etching prior to 4H-SiC Homoepitaxial Growth
We have investigated the influence of in-situ H2 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 H2 etching; namely, hydrogen (H2) alone, hydrogen-propane (H2+C3H8), and hydrogen-silane (H2+SiH4). We found that in-situ H2 etching using H2 + SiH4 significantly improved the surface morphology of 4H-SiC substrate just after in-situ H2 etching. By adding SiH4, formation of bunched step structure during in-situ H2 etching could be significantly suppressed. In addition, H2 etching using H2 + SiH4 was able to remove scratches by etching a thinner layer than that using H2 alone. We also discussed the in-situ H2 etching mechanism under the additional SiH4 condition.
Effect of growth condition on micropipe filling of 4H-SiC epitaxial layer
Abstract In this study, we studied the effect of growth conditions on micropipe (MP) filling during 4H–SiC epitaxial growth. We found that an MP in an on-axis substrate was filled during epitaxial growth and that this MP was filled with a spiral growth. The MP filling on on-axis substrates had a high probability and was independent of growth conditions. On the other hand, the probability of MP filling of 8° off-axis substrates showed a strong dependence on the growth pressure and the growth rate. The probability of MP filling increased with decreasing growth pressure or increasing growth rate. The probability of MP filling of the C-face was higher than that of the Si-face. From a comparison of a numerical simulation and experimental results, we found that the concentration of Si species just above the substrate was a crucial factor for MP filling.