Time-resolved plasma characterisation of modulated pulsed power magnetron sputtering of chromium

Time-resolved Langmuir probe measurements have been employed to investigate the temporal development of the plasma properties, such as electron and ion density, electron temperature as well as the floating and plasma potential, during Modulated Pulsed Power Magnetron Sputtering (MPPMS). A chromium target was sputtered with an average power of 650 W in an argon atmosphere (0.53 Pa) employing two steps of excitation of the discharge which was realised by altering the modulation frequency of the voltage supplied to the target. The overall pulse duration was kept at 750 μs and a repetition frequency of 100 Hz was used. Three distinct stages of the discharge, namely the initial and the second step of excitation as well as the transition region which connects both stable states, were found. Maximum electron densities up to 7 × 10¹¹ cm^? 3 were obtained during the transient phase.