Fabrication of smooth β-SiC surfaces by reactive ion etching using a graphite electrode

Reactive ion etching (RIE) of cubic β-SiC in an SF6/O2 plasma has been investigated using powered electrodes made from graphite and aluminum. With the graphite electrode the etched surfaces were smooth and shiny and had no column-like structures for any etching conditions while with the Al electrode the surfaces were dull and showed residues under the scanning electron microscope. This effect was observed with and without Al as the etch mask material. The etch rates of β-SiC were investigated as functions of the SF6/O2 ratio, the power, the pressure in the reactor chamber and the etching time. Up to a factor of two higher etch rates were obtained when the graphite electrode instead of the Al electrode was used. Since β-SiC is deposited on Si the etch rates of Si and the SiC/Si etch rate ratio were investigated for different O2 concentrations in the plasma.