Mass Spectrometry of Discharge Products at 13.56 MHz in SF6Gas

Discharge products in SF6RF plasma were measured by means of direct sampling using a quadrupole mass spectrometer. In the plasma, the neutral dissociative species SF2and SF4are present. The positive ion SF3+is predominant, and SF5+, SF2+, SF+and F+are also present. The concentration of each neutral and ion product depends on RF power, gas flow rate and area of the silicon wafer set on the grounded electrode. When SF, SF2, SF+and SF2+increase to certain amounts, S2F+, SF2+and S+can be observed.