Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. This paper deals with two-dimensional density mapping in the discharge volume obtained by laser-induced fluorescence imaging. The time-resolved density evolution of Ti neutrals, singly ionized Ti atoms (Ti þ ), and Ar metastable atoms (Ar met ) in the area above the sputtered cathode is mapped for the first time in this type of discharges. The energetic characteristics of the discharge species are additionally studied by Doppler-shift laser-induced fluorescence imaging. The questions related to the propagation of both the neutral and ionized discharge particles, as well as to their spatial density distributions, are discussed. V C 2015 AIP Publishing LLC.

No abstract

The velocity distribution function of the sputtered particles in the direction parallel to the planar magnetron cathode is studied by spatially- and time-resolved laser-induced fluorescence spectroscopy in a short-duration (20 μs) high-power impulse magnetron sputtering discharge. The experimental evidence for the neutral and ionized sputtered particles to have a constant (saturated) velocity at the end of the plasma on-time is demonstrated. The velocity component parallel to the target surface reaches the values of about 5 km/s for Ti atoms and ions, which is higher that the values typically measured in the direct current sputtering discharges before. The results point out on the presence of a strong gas rarefaction significantly reducing the sputtered particles energy dissipation during a certain time interval at the end of the plasma pulse, referred to as “rarefaction window” in this work. The obtained results agree with and essentially clarify the dynamics of HiPIMS discharge studied during the plasma off-time previously in the work: N. Britun, Appl. Phys. Lett. 99, 131504 (2011).

No abstract

The gas heating dynamics is studied in a high-power impulse magnetron sputtering discharge operating in Ar-N2 gas mixtures. The time-resolved rotational temperature analysis based on the spectral transition between the B2Σu+-X2Σg+ energy levels in molecular nitrogen ion (N2+ First Negative Band) is undertaken for this purpose. The rotational temperature in the discharge is found to increase linearly during the plasma pulse being roughly independent on the nitrogen content in the examined range. Such a temperature increase is attributed to the bulk gas heating which is the result of collisions with the sputtered species. Two sputtered materials, Ti and W, are examined during the study. In the case of W sputtering, the gas heating is found to be more pronounced than in the Ti case, which is explained by more efficient energy exchange between the sputtered W atoms and the bulk gas atoms during the plasma on-time. The obtained temperature data are compared to the laser-induced fluorescence study of Ar metastable atoms performed recently in the same discharge in our group. The particularities related to gas thermalization as well as to validity of the utilized approach for characterization of the pulsed sputtering discharges are discussed.

A super-exponential time-relaxation of the full width at half maximum of Ti and Ti+ spectral lines was found during the off-time in a high-power impulse magnetron sputtering discharge studied by laser-induced fluorescence. After the estimation of the possible broadening mechanisms, the main contribution to the determined linewidths appeared to be the broadening due to ballistic motion of sputtered species with a minor contribution of the instrumental and Doppler broadenings. The deconvoluted linewidths depend both on pressure and distance from target, and their time-decay was attributed to the fast energy relaxation of the sputtered neutrals and ions during the off-time.

No abstract

Not available