The role of argon metastables in operation and uniformity of planar RF inductively coupled discharges

Summary form only given, as follows. Measurements of argon metastable line densities along a radial chord in a cylindrical (20 cm D by 14 cm long) ICP discharge are made with a newly constructed broadband xenon arc lamp optical absorption spectroscopic diagnostic. The application of this absorption system is not restricted to argon; the lamp has a continuous spectrum from the ultraviolet to the near infrared. Concentrations of the 1S/sub 3/ and 1S/sub 5/ argon metastable states will be determined, by measuring absorption lines at 795 and 811 nm, respectively. The planar spiral induction antenna is driven at 13.56 MHz. Trends in metastable concentration, as well as Langmuir probe measurements of electron density, with pressure (5-200 mTorr) and power (100-750 watts) are presented and are compared with predictions from the fluid model. Predicted trends in the percent of ionization from metastables and excited levels with pressure and power are also presented. The influence of, metastables on the electron density is examined by comparing fluid code results for electron density with and without the contribution of two-step ionization from metastables.