Planar laser-induced fluorescence of CF2 in O2/CF4 and O2/C2F6 chamber-cleaning plasmas: Spatial uniformity and comparison to electrical measurements

Abstract

Planar laser-induced fluorescence (PLIF) measurements were made to determine two-dimensional spatial maps of CF2 density as an indicator of chemical uniformity in 92% CF4/O2 and 50% C2F6/O2 chamber-cleaning plasmas at pressures between 13.3 Pa (100 mTorr) and 133.3 Pa (1000 mTorr). Measurements were also made of broadband optical emission and of discharge current, voltage and power. All measurements were made in a Gaseous Electronics Conference Reference Cell, a capacitively coupled, parallel-plate platform designed to facilitate comparison of results among laboratories. The CF2 PLIF and emission results were found to correlate with discharge current and voltage measurements. Together, these optical and electrical measurements provide insight into the optimization of chamber-cleaning processes and reactors, suggest new methods of monitoring plasma uniformity, and identify important spatial effects which should be included in computer simulations.