Schematics of the experimental setup for OES measurements in a HiPIMS discharge.
Typical current (I), voltage (U) and resulting power (P) normalized waveforms produced in the HiPIMS discharge during Ti (a) and W (b) sputtering. The integral energy supplied per pulse (EP) is given for illustration. I(t) waveforms are made negative for the sake of data visibility. Pulse duration is 20 μs.
(a) The FNB of N2 + measured at Δt = 10 μs in the Ar-W-N2 gas mixture. Pulse duration is 20 μs. Inset: An example of the Boltzmann plot built based on the marked N2 rotational peaks. N2 content = 30%, EP = 0.44 J. (b). The same rotational band synthesized at close gas temperature.
The emission spectra corresponding to the N2 FNB measured in the HiPIMS discharge at Δt = 8 μs (a) and (b) and Δt = 16 μs (c) and (d). The metallic (Ti, W) emission lines are visible at the larger time delay. The emission intensity is given in the same scale for the corresponding sputtered materials.
Time-resolved Trot elevation during a 20 μs HiPIMS pulse in the case of W (a) and Ti (b) sputtering, measured at different EP, and different N2 contents. The shown error bars correspond to the Boltzmann plot fitting errors.
Trot attained at the beginning (Tmin) and at the end (Tmax) of a HiPIMS plasma pulse obtained based on the linear fits of the time-evolution data shown in Fig. 5 . The results are presented for W (a) and Ti (b) sputtering at different Ep values and different N2 contents. The dashed lines schematically indicate the trends of the gas temperature behavior.
Comparison between the rotational temperatures measured during the HiPIMS pulse using the FNB of N2 + and FPB of N2 rotational bands in the Ar-W-N2 sputtering case. Two values of the energy EP are shown. The N2 content is 50%. Pulse duration is 20 μs.
The normalized ArM velocity distributions (without deconvolution) measured by LIF in an Ar-Ti HiPIMS discharge at two different Ar pressures. EP = 0.25 J, distance from target = 45 mm, Δt = 20 μs (end of the plasma pulse). After deconvolution with the laser linewidth the temperatures corresponding to the thermalized parts of the vdfs are found to be 510 ± 20 K (20 mTorr) and 650 ± 40 K (5 mTorr).
The fitting parameters of the vdfs presented in Fig. 8 along with the calculated Ar temperatures (TAr).
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