An atmospheric-pressure microplasma jet (µ-PJ) using RF (13.56 MHz) corona discharge was generated at the tip of a stainless steel surgical needle of 0.4 mm outer diameter at a RF power of 6–14 W. The needle functions as both a powered electrode and a narrow nozzle. The µ-PJ with a gas mixture of He/SF6/O2 was applied to localized Si etching. The etched profile exhibited an isotropic shape and the etch rate had a maximum value at the total gas flow rate of about 600 sccm and the SF6 concentration of 5%. The etch rate of 170 µm/min was obtained at a RF power of 14 W.