Studies on C22 radical by optical emission spectroscopy in an induc tively-coupled CF44/CH44 plasma

Abstract

In this paper, actinometric optical emission spectroscopy (AOES) is used to inve stigate the discharge of CF44 and CH44 mixtures. Relat ive concentratio ns of radicals in an inductively_coupled plasma are determined as functions of rf input power, pressure and the gas flow ratio R (R=［CH44］/{［CH 44］+［CF44］}). It is found that CF，CF22 ，CH，H and F radicals exis t in the CF44/CH44 plasma as well as C22 radical. The relative co ncentration of C22 increases with increasing power, and shows a rev erse “U” shape tendency with increasing pressure. As R increases, the variati on of the relative concentration of C22 is not monotonical. It reac hes a ma ximum value when Ｒ＝75%, then decreases followed by almost no change with the further increase of R. Based on these results, it is concluded that gas_pha se reaction from the reaction of CF and CH （ＣＦ＋ＣＨ→Ｃ２2＋ＨＦ ） contribu tes to the production of C22 radical. At the same time, activation reaction model of radical collision is suggested. Result of simulation agrees well with that of experiment.