C. Nouvellon

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%.

Emission spectrometry diagnostic of sputtered titanium in magnetron amplified discharges

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.

RF amplified magnetron source for efficient titanium nitride deposition

Amplified magnetron sources are used to increase the ionization ratio of the sputtered metallic species in a way to avoid shadowing effect during thin film deposition on complex substrates. An radio-frequency (RF) power supplied coil achieves the amplification of the magnetron plasma. In this paper, an amplified magnetron discharge in Ar-N 2 mixtures for titanium nitride (TiN) deposition has been studied by energy-resolved mass spectrometry. The purpose of the work is to observe the influence of the RF coil power on the hysteresis phenomenon, the ion energy distributions and the species present in the plasma (mass spectra). Concerning the hysteresis, we observe that the metal-nitride transition shifts to higher values of the nitrogen partial mass flow in the amplified mode. The discharge voltage is also decreased when 500 W r.f. are injected into the plasma. Both these effects are attributed to an increased ion bombardment of the titanium target. The shape of the ion energy distribution function is also changed. Low energy shoulder, due to charge exchange reactions in the sheath, is observed for Ar + , N + 2 and N + . Ti + and N + signals exhibit high-energy tail. The mass spectra have shown interesting results, the TiN + molecular ion is present when the RF coil is on.