Research on the Gas Effect of Octafluorocyclobutane Plasma Jet at Atmospheric Pressure for Silicon Etching

The capacitively coupled radio frequency double-pipe plasma discharge jet is used for the etching process. An argon carrier gas is fed through the atmospheric-pressure plasma source; octafluorocyclobutane (C ₄ F ₈ ) etch gas is injected into the plasma. Etchings were carried out on a crystalline silicon substrate. The etching characteristics are discussed and the etch rate tendency shows the reliance of C ₄ F ₈ gas flow rate and oxygen addition. The optimum etching rate of $7.2~\mu \text{m}$ /min was obtained at a plasma power level of 100 W and C ₄ F ₈ gas flow rate was 250 sccm. From surface profile detection, it displays the etch profile under this atmospheric-pressure plasma jet treatment. This plasma technique could offer a breakthrough for chamber-free dry etching processing.