Time-resolved plasma parameters in the HiPIMS discharge with Ti target in Ar/O2 atmosphere

A High Power Impulse Magnetron Sputtering System (HiPIMS) equipped with a titanium target 5 cm in diameter has been investigated by means of a time-resolved Langmuir probe and time-resolved ion flux probe. The plasma parameters have been measured in a distance of 70 mm from the target face and below the racetrack. The ion flux at the substrate (placed at the same position as the Langmuir probe) has been determined from the voltage drop across a resistor connected with the planar probe. The planar probe was pulsed at a repetition rate of 50 kHz, duty cycle 50%. The effects of working gas pressure and mean discharge current have been investigated. Fine temporal resolution of the measured probe characteristics revealed a decrease in the effective electron temperature T-eff during pulse-ON time followed by a steady value at 0.6 eV for all the pressures during the rest of the period. For the pressure of 2 Pa, we observed a local maximum in T-eff (0.9 eV) at the end of cathode voltage pulse. Furthermore, during the pulse-OFF time we observed an exponential-like decay of the electron temperature for all the pressures. The plasma density demonstrated a steep increase during pulse-ON time followed by an exponential-like decrease during plasma OFF phase. The ion flux measurements have revealed approximately 3 times higher magnitude in the ion flux on the substrate at low pressure than at higher-pressures. The influence of these phenomena on the total energy flux at substrate and on thin film properties is discussed. (C) 2010 Elsevier B.V. All rights reserved.