Study of effect of H 2 addition on the production of fluorocarbon radicals in H 2 /C 4 F 8 inductively coupled plasma via optical emission spectroscopy actinometry

Abstract

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 ratioR=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.