Use of optical absorption spectroscopy for the characterization of an Ar?Ti magnetron discharge

The density of ground state and metastable Ti atoms were measured in a magnetron sputtering reactor with a 10 cm diameter Ti target by using resonant optical absorption spectroscopy. Experiments were conducted under various discharge parameters, namely the discharge current (0.2 A to 1.2 A) and the distance from the target (2 cm to 12 cm) under two working pressures (0.5 Pa and 4 Pa). The results were compared with previous results for a smaller magnetron source with a 5 cm diameter target. The Ti densities were as follows: Ti]≈10¹¹ cm⁻³, Ti_m]=10¹⁰ to 10¹¹ cm⁻³ for 0.5 Pa and Ti]≈Ti_∞]=10¹⁰ to 10¹² cm⁻³ for 4 Pa. The portion of Ti metastables in the discharge increases by a factor of approximately 2 as the working pressure increases.