Analysis of a CF4/O2 plasma using emission, laser-induced fluorescence, mass, and Langmuir spectroscopy
- 15 April 1990
- journal article
- Published by AIP Publishing in Journal of Applied Physics
- Vol. 67 (8) , 3635-3640
- https://doi.org/10.1063/1.345317
Abstract
The behavior of CF2 radicals in CF4/O2 plasmas has been studied as a function of the oxygen partial pressure in an rf reactor with 13.56 MHz, 30 W, and 40 mTorr total pressure. The CF2 ground and excited states were detected by the CF2 (A‐X) band spectra applying laser‐induced fluorescence and optical emission spectroscopy, respectively. Adding oxygen to the CF4 feed gas, the intensity of the CF2 signals in both spectra showed similar decrease. No evidence is found for a simple correlation between the neutral CF2 densities and the CF+2 ions measured by quadrupole mass spectrometry. Electron densities and temperatures were evaluated to be slightly above 8×109 cm−3 and ∼5 eV, respectively. A simplified model, which takes into account different excitation paths, suggests that direct electron impact of the CF2 ground state species was the dominant mechanism for the population of the electronically excited state. Absolute CF2 and O concentrations depending on the oxygen feed could be estimated. We obtained CF2 densities between 2×1013 and 2×1012 cm−3, when the oxygen concentration increases from 2% to 23%. The corresponding O densities varied from 1012 to 6×1013 cm−3.This publication has 25 references indexed in Scilit:
- Optical techniques in plasma diagnosticsPublished by Walter de Gruyter GmbH ,1984
- Silicon etching mechanism and anisotropy in CF4+O2 plasmaJournal of Applied Physics, 1983
- A study of Si plasma etching in CF4+O2 gas with a planar-type reactorJournal of Applied Physics, 1983
- Detection of CF2 radicals in a plasma etching reactor by laser-induced fluorescence spectroscopyApplied Physics Letters, 1982
- A kinetic study of the plasma-etching process. II. Probe measurements of electron properties in an rf plasma-etching reactorJournal of Applied Physics, 1982
- Laser-Induced Fluorescence Diagnostics of CF4/O2/H2 Plasma EtchingMRS Proceedings, 1982
- Dependence of F atom density on pressure and flow rate in CF4 glow discharges as determined by emission spectroscopyJournal of Vacuum Science and Technology, 1981
- Spectroscopic diagnostics of CF4-O2 plasmas during Si and SiO2 etching processesJournal of Applied Physics, 1981
- Decomposition and product formation in CF4-O2 plasma etching silicon in the afterglowJournal of Applied Physics, 1981
- Plasma etching of Si and SiO2—The effect of oxygen additions to CF4 plasmasJournal of Applied Physics, 1978