Study of effect of H₂ addition on the production of fluorocarbon radicals in H₂C₄F₈ inductively coupled plasma via optical emission spectroscopy actinometry

C₄F₈ plasma with the addition of H₂ is generated by the inductively coupled plasma (ICP) method. The relative densities of CF,CF₂, H and F radicals are determined by actinometric optical emission spectroscopy (AOES) as a function of the gas flow rate ratio R=H₂/(H₂+C₄F₈ at a pressure of 0.8 Pa and an input r.f.power of 400W, while that of HF is measured by quadrupole mass spectrometry (QMS). The results show that plasma activity increases firstly and then decreases with increasing R. As the gas flow rate ratio R changes from 0 to 0.625, relative densities of both CF and CF₂ decrease, and the relative CF has a similar tendency as the calculated CF, indicating that CF radicals are generated mainly by the electron impact dissociation of CF₂ radicals. Production of HF is also discussed.