Experimental study of an RF magnetron discharge for thin-film deposition

An investigation by optical emission spectroscopy and Langmuir probe was performed on an RF magnetron discharge used to sputter deposit tungsten and titanium in an argon plasma. The dependence on gas pressure and RF power of some Ti, W and Ar emission line intensities, electron density and temperature are studied in the center of the discharge. A simple model for the excitation process of the Ar, W and Ti atoms allows us to calculate the density of sputtered atoms in the plasma. The variations of electron density as a function of argon pressure and discharge power obtained by probe measurements are well correlated with the Ar (750.4 nm) line intensity. Owing to the transport regime of W and Ti sputtered species across the discharge, the existence of a correlation between the target composition, tungsten and titanium densities in the plasma and film composition on the substrate must be studied carefully. (C) 1997 Elsevier Science S.A.