Pulsed dc magnetron discharges and their utilization in plasma surface engineering

Fundamental aspects of magnetron operation in two types of practically interesting discharges, i.e. in high-power unipolar pulsed dc magnetron discharges for ionized high-rate sputtering and in asymmetric bipolar pulsed dc magnetron discharges for reactive sputtering, were investigated on the basis of time-resolved plasma diagnostics. We present the results obtained using time-resolved optical emission spectroscopy and time- and energy-resolved mass spectroscopy in high-power unipolar pulsed dc magnetron discharges at a repetition frequency of 1 kHz, an argon pressure of 1 Pa and an average target power loading in a pulse up to 500 W/cm². The main aim was to study complex ionization mechanisms of sputtered Cu atoms and working gas (Ar) atoms, and to characterize energy distributions of Cu⁺ and Ar⁺ ions and their fractions in ion fluxes to a substrate during pulses. Some results achieved with a grooved target at the frequencies up to 50 kHz are discussed. We report also on the results obtained using energy-resolved mass spectroscopy and time-resolved Langmuir probe measurements in asymmetric bipolar pulsed dc magnetron discharges at repetition frequencies of 100 kHz and 350 kHz, an argon pressure of 0.53 Pa and a mean discharge power of 300 W. They explain a complex correlation between the pulsed plasma dynamics and the enhanced ion bombardment of growing films in these discharges. Some new development trends in the field of the dual pulsed dc magnetron sputtering are outlined.