TIME-RESOLVED OPTICAL PLASMA DIAGNOSTICS OF THE CATHODE REGION OF A VACUUM (GASLESS) MAGNETRON SPUTTER

We report on our experimental studies of time-resolved optical diagnostics using an intensified charge-coupled device (ICCD) camera to monitor possibility of formation the localized ionization zones ("spokes") in a planar magnetron sputtering system in direct current (DC) vacuum (gasless) mode of operation. To verify the experimental equipment used to observe localized ionization zones and correlate ionization processes in the gas and vacuum discharge modes, a high-current pulsed mode of magnetron discharge in a typical argon pressure range of several millitorr was also used. It is shown that no spokes are formed in DC vacuum mode. The appearance of a plasma glow over the racetrack region shows that the ionization processes in a vacuum magnetron are similar to those in high-current pulsed modes of magnetron discharge with current of > 200 A, which also provide a high proportion of metal particles and lack localized ionization zones.