H 2 etching and epitaxial growth on 4H-SiC boule domes

Silicon carbide (SiC) is a semiconductor material intended for high-temperature and high-power switching device applications. One of the main concerns in SiC is basal plane dislocations (BPD), which cause devices to fail. Many researchers have strived to reduce these dislocations with some progress by varying pre-growth treatments and growth parameters; however, more efforts are needed to overcome the issue. Conventional 4H-SiC growth takes place on 8deg off-axis substrate, which results in smooth morphology due to step flow growth. However, it is known that growth on off-axis substrates allows many BPDs to propagate into the subsequent epilayers which comprise of the active region of the device. One way to reduce propagation of these dislocations is to grow on low off-axis material. Unfortunately as the off-cut is lowered, the morphology worsens and step bunching dominates. This study aims at reducing step-bunching on low off-axis angles (< 4deg) during both etching and epitaxial growth, while simultaneously reducing basal plane dislocations by experimenting on boule domes with various off-axis angles.