Emission spectrometry diagnostic of sputtered titanium in magnetron amplified discharges

Abstract

The plasma of a dc discharge amplified by a rf coil is studied by emission spectroscopy. The effects of the induction coil are studied for titanium sputtered in an argon gas. The pressure range is 5–40 mTorr with 100 to 1000 W dc applied at the cathode and 0 to 500 W in the rf coil. The titanium emission line intensities are reported versus rf power. At high rf power and high pressure, titanium emission saturates while there is a linear increase with rf power for titanium ions emission. These results suggest a two-step mechanism for the production of excited titanium ions. With such a mechanism, titanium neutral is mainly lost by ion production (the diffusion loss is lower) and titanium ion is mainly lost by diffusion (loss by second ionization of Ti+ is weak). The Ti/Ar emission line ratio, representing the titanium density, decreases when a rf power is applied to the coil as a result of an efficient titanium ionization reaction by electrons.