Using a fast electrostatic gating technique the ion energy distribution functions (IEDF's) at the substrate in a High Power Impulse Magnetron Sputtering (HIPIMS) discharge have been determined with a 2μs time-resolution. The discharge was operated with a repetition rate of 100Hz, a pulse width of 100μs, a pressure of 0.26Pa and a peak power density of 2.5kW cm~(-2). The results show that Ar~+ ions appear 8μs after initiation of the discharge voltage pulse and have a narrow distribution of energies, consistent with being created locally to the substrate; as seen by plasma potential measurements. The time-evolution of the plasma potential (1μs time-resolution) was obtained using a Langmuir probe close to the mass spectrometer extraction orifice. In contrast to the Ar~+ ions, sputtered post-ionised atoms in the form of Ti~+ ions were detected 14μs after the pulse initiation, showing a distinct high-energy tail extending up to about 100eV. The form of the IEDF's for these ions is believed to be determined by both the energy distribution of the sputtered atoms from the target and the space potential in the bulk plasma at which they were ionized.
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