Ion fluxes and energies in inductively coupled radio-frequency discharges containing CHF3

Abstract

Measurements of ion energy distributions, relative ion intensities, and absolute total ion current densities were made at the grounded electrode of an inductively coupled Gaseous Electronics Conference (GEC) radio-frequency reference cell for discharges generated in CHF3 and its mixtures with argon. In general, the dominant ion species detected were not due to direct ionization of the CHF3 feed gas. Results are presented for plasmas generated with and without a confining quartz annulus that has recently been used to extend the operating parameter range of inductively coupled GEC cells for certain etching gases. Compared to similar plasmas generated without the annulus, the presence of the ring increases the ion flux density by approximately a factor of 2, and increases the mean ion energies. The presence of the ring does not significantly affect the measured relative ion intensities.