Reactive ion etching of silicon carbide in SF_(6) gas: Detection of CF, CF_(2), and SiF_(2) etch products

摘要

We have detected by laser-induced fluorescence the radicals SiF_(2), CF, and CF_(2) produced during the reactive ion etching of SiC substrates in a pure SF_(6) plasma. Spatially and temporally resolved measurements were used to distinguish between gas phase and etched surface radical production. Whereas CF and CF_(2) are produced directly at the etched surface, the SiF_(2) radicals are produced in the gas phase (probably by electron-impact dissociation of SiF_(4)). We attribute this difference to the formation of a carbon-rich layer on the SiC substrate surface, the removal of which produces CF_(x) (x=1,2,3) radicals. The CF_(2) radical represents up to 20 of the total carbon etch products under our conditions.