High temporal resolution ion energy distribution functions in HiPIMS discharges

摘要

A technique for obtaining high time resolution ion energy distribution functions (IEDFs) at the substrate in depositing plasma has been demonstrated, and applied to a high power impulse magnetron sputtering (HIPIMS) discharge. Key to this technique is the electrostatic gating of ions inside the instrument end cap. To demonstrate the performance of this technique, IEDF measurements with a 2 µs time-resolution have been made with the following HIPIMS operating conditions: a repetition rate of 100 Hz, a pulse width of 100 µs, a pressure of 0.26 Pa and a peak power density of 2.5 kW cm-2. The orifice of the mass spectrometer was positioned facing the racetrack region of the circular magnetron cathode. The Ar+ ions were detected 8 µs after initiation of the discharge voltage pulse, exhibiting a narrow distribution of energies, while Ti+ ions were detected 14 µs after the initiation, showing a high-energy tail extending up to 100 eV. The time-evolution of Ti+ ions show that the metal flux starts to be built up at the substrate position at times 20 µs after the pulse initiation.