Comparison of Chlorine Based In Situ Etching of 4H SiC Substrates

Gas phase etching of 4H SiC n+ substrates was performed utilizing chlorine containing etch chemistries in a hot wall CVD system. Carbon and silicon vapor were added to explore selective etching reactions on the wafer surface. The impact of the etch on the bare wafer surface as a function of temperature and etch chemistry is investigated. Selection of the etch chemistry and temperature are critical to ensure a smooth etched surface on which to begin epitaxial deposition. Etching also influences defect propagation from the substrate into the epitaxial layer. The results show etch chemistry reactions will influence the conversion of micropipes in the epi buffer layer.