Relative atomic chlorine density in inductively coupled plasmas containing chlorine and boron trichloride

Two photon allowed laser induced fluorescence has been used to measure the relative atomic chlorine density in inductively driven radio frequency discharges containing mixtures of chlorine, boron trichloride, argon and nitrogen. In contrast with previous measurements in pure chlorine discharges, the atomic chlorine density increased with rf power in pure BCl3 discharges. In mixtures of Cl2 and BCl3, the Cl density was constant with rf power and increased with pressure, similar to pure Cl2 discharges. In addition, the Cl density varied linearly with Cl2/BCl3 ratio, and was a factor of three higher in pure Cl2 than in pure BCl3. The addition of argon or nitrogen to BCl3/Cl2 mixtures had no effect on the relative Cl density. Finally, measurements of the Cl density as a function of spatial location showed that the Cl density was uniform in the discharge region. Several gas phase chemical mechanisms in Cl2/BCl3 plasmas are hypothesized based on the atomic chlorine measurements presented in this work with previous measurements of other gas phase plasma species in this reactor geometry.