A Technique for Temperature Mapping in Fluorocarbon Plasmas Using Planar Laser-Induced Fluorescence of CF
Kristen L. Steffens, Mark A. Sobolewski
Planar laser-induced fluorescence (PLIF) measurements of CF A2S+ - X2P (1,0) were used to determine two-dimensional maps of rotational temperature in CF4 plasmas. Measured rotational temperatures are expected to be in equilibrium with the gas temperature due to the long chemical lifetime of CF relative to the collision rate. Experiments were performed in the capacitively-coupled Gaseous Electronics Conference rf Reference Cell at pressures from 200 mTorr (26.7 Pa) to 800 mTorr (107 Pa) and powers of 10 W to 30 W deposited in the plasma. Temperatures ranged from 273 K 15 K to 480 K 15 K and were fairly axially symmetric, increasing with pressure and power. All plasmas were coolest near the electrodes, which provide a substantial sink for heat in the plasma due to conduction and diffusion. Highest temperatures were found at a radial position near the edge of the electrodes. The strong temperature gradients observed in the plasmas can have serious effects on density measurements that probe a single rotational level, as well as on reaction rate constants and interpretation of density gradients. The effects of water cooling the electrodes and the presence of a silicon wafer on temperature were also measured.
Journal of Applied Physics
CF, laser-induced fluorescence, LIF, plasma, PLIF, spectroscopy, temperature
and Sobolewski, M.
A Technique for Temperature Mapping in Fluorocarbon Plasmas Using Planar Laser-Induced Fluorescence of CF, Journal of Applied Physics
(Accessed September 25, 2023)