Density and temperature in an inductively amplified magnetron discharge for titanium deposition

In order to determine the titanium neutral density, a direct current (dc) plasma discharge, amplified by a radio-frequency (rf) coil, was studied by absorption spectrometry. The argon pressure varied from 5 to 40 mTorr. The dc and rf powers varied between 100 and 1500 W and 0 and 500 W, respectively. The plasma gas temperature necessary for the density calculation was evaluated by analyzing the N2 rotational spectrum in an Ar–N2 gas mixture. When increasing the rf power a decrease of titanium neutral density was found. This decrease is related to the increased titanium ion density. When using the rf coil, the titanium degree of ionization can be up to 90%.