PLASMA-ETCHING OF SILICON-CARBIDE USING SF6 O-2 GAS-MIXTURE AND ITS APPLICATION TO THE FABRICATION OF 6H-SIC PN JUNCTION DIODES/

We have investigated the plasma etching characteristics of SH-silicon carbide using SF6 and O-2 gas mixture. The etch rates have been determ ined as functions of gas composition, RF power, cathode to anode dista nce, and gas flow rate. The ranges of etching parameters were 20 simil ar to 240 W of RF power, 20 similar to 65 seem of total gas flow, and 40 similar to 80% of oxygen composition in the SF6/O-2 gas mixture. A typical etch rate of 270 Angstrom/min has been achieved with an RF pow er of 200 W (power density=4.0 W/cm(2)), gas mixing ratio of 50%/50%, total gas flow rate of 40 seem, and cathode to anode distance of 60 mm . The dependence on the O-2 composition indicates that nearly equal nu mber of [F] radicals and O-2(+) ions participate in the etching proces s. The plasma etching technique has been employed to fabricate mesa-ty pe 6H-SiC pn junction diodes using epitaxial n(+)-n-p GH-SIC wafer. A reverse breakdown voltage of:150 V has been observed from the pn junct ion diode.