Ionized particle transport in reactive HiPIMS discharge: correlation between the energy distribution functions of neutral and ionized atoms

Farsy, A. El; Boivin, D.; Noël, Cédric; Hugon, R.; Cuynet, Stéphane; Bougdira, J.; Poucques, Ludovic de

doi:10.1088/1361-6595/ac02b4

Cited by 5 publications

(3 citation statements)

References 40 publications

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“…The transport velocity obtained may seem to be high; however, it should be noted that this velocity corresponds to fast, only partially thermalised atoms. Similar or even higher velocities were very recently observed by using TR-TDLIF [80,81]. This suggests that the volume is indeed already strongly rarefied, making it possible for particles to transit towards the substrate with fewer collisions, similarly to experimental observation [26,27] and simulation [82].…”

Section: Time-resolved Measurement In the Low-current (Lc) Conditions...supporting

confidence: 84%

Temporal studies of titanium ionised density fraction in reactive HiPIMS with nitrogen admixture

Bernátová¹,

Klein²,

Hnilica³

et al. 2021

Plasma Sources Sci. Technol.

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Temporal evolutions of the ground state number densities of titanium atoms and ions and the ionised density fraction during pulse on-time are experimentally investigated for the high-power impulse magnetron sputtering process in an Ar and Ar/N2 atmosphere. For the study, two distinct pulses with the same pulse length at a constant average power but different pulse off-times were selected. In both conditions, four representative points within the hysteresis curve were chosen, and the time evolutions of sputtered species densities were investigated in both the target and the substrate regions. At the pulse beginning, a high density of residual particles sputtered during the previous pulse is present in both studied regions. In the target region, in conditions of longer pulse off-time and thus higher peak discharge current, 95% of sputtered particles are ionised in metallic, transition and compound regimes. With shorter pulse off-time conditions, and thus a lower peak discharge current, the ionised density fraction is the lowest in the metallic regime; in the transition and compound regimes, it exceeds 80%. In the substrate region, the temporal evolution of sputtered species densities differs from that obtained in the target region. After the pulse ignition, titanium atoms and ions remaining near the substrate from the previous pulse are pushed away. In the metallic regime, the sputtered atoms refill the substrate region already during the pulse on-time in both the low- and high-current conditions. In the high-current conditions, the titanium ions arrive at the substrate together with the sputtered atoms; however, in the low-current conditions, the titanium ion density decreases during the pulse on-time, and the titanium ions arrive later during the pulse off-time. In the transition and compound regimes, both densities steadily decrease during the pulse on-time and the titanium atoms and ions arrive at the substrate during the pulse off-time.

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Section: Time-resolved Measurement In the Low-current (Lc) Conditions...supporting

confidence: 84%

Temporal studies of titanium ionised density fraction in reactive HiPIMS with nitrogen admixture

Bernátová¹,

Klein²,

Hnilica³

et al. 2021

Plasma Sources Sci. Technol.

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“…The low-energy group of ions is thermalized with the buffer gas. The high-energy group has been studied in many works, especially in HiPIMS discharge [28][29][30], and is generally attributed to ion acceleration inside spokes in magnetron plasma. As shown in figure 4, the signal magnitude of this high-energy group is three orders of magnitude lower than that of the thermalized ions.…”

Section: Influence Of Deposited Energy On the Film Microstructure Tex...mentioning

confidence: 99%

On the correlation between the TiN thin film properties and the energy flux of neutral sputtered atoms in direct current magnetron discharge

Farsy¹,

Pierson²,

Gries³

et al. 2022

J. Phys. D: Appl. Phys.

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In this study, the energy flux of sputtered atoms on a substrate was correlated to the properties of titanium nitride (TiN) films deposited using direct current magnetron sputtering (dcMS) un-der mixed Ar and N2 atmospheres. The neutral titanium sputtered atoms velocity distribution functions (AVDFs) were measured by tunable diode-laser induced fluorescence (TD-LIF), and the flux of particles and their energy were derived. Mass spectrometry was used to character-ize the energy-resolved flux of the ions. It was found that the neutral sputtered atoms flux and deposition rate were in good agreement, indicating that the flux of the neutral titanium ground state represents the number of deposited atoms. Moreover, TiN films were deposited at dif-ferent gas pressures and at various Ar/N2 gas mixtures close to the conditions where stoichio-metric TiN was formed, without bias voltage and heating of the substrates. The energy flux of the sputtered neutral Ti into the substrate was calculated from TD-LIF measurements. At a rel-atively low magnetron discharge pressure of 0.4 Pa, we demonstrated that the energy of sput-tered neutral Ti impinging on the substrate is higher than the energy flux of ionized particles corresponding mainly to Ar+. Thus, the influence of the energy flux of the sputtered atoms on the texture and microstructure of the films is revealed. The (200) texture was obtained at 0.4 Pa when the energy flux of the sputtered atoms was higher than the ion energy flux. At 1.3 Pa where the sputtered atoms energy flux is one order lower compared to 0.4 Pa the (111) tex-ture was obtained. The high-energy flux of the ground state of Ti sputtered atoms seems to al-low stress removal in the films.

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“…On the contrary, Tunable Diode Laser Induced Fluorescence (TD-LIF) technique fills these requirements, and it was used here. It offers a good space resolution (of the order of a few mm 3 ) [7] and a very good time resolution (below 1 µs) [30,19]. Therefore, it is highly suitable to study the inhomogeneity of the densities and the fluxes from the target to the substrate, with high spectral resolution and relatively wide scanning range of wavelength (about 18 GHz without hope mode).…”

Section: Introductionmentioning

confidence: 99%

Transition from ballistic to thermalized transport of metal-sputtered species in a DC magnetron

Revel

Farsy

Poucques

et al. 2021

Plasma Sources Sci. Technol.

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Tunable Diode Laser Induced Fluorescence (TD-LIF) technique has been optimized to accurately measure the titanium (Ti) sputtered Atoms Velocity Distribution Functions (AVDF) in a magnetron discharge operating in Direct Current (DC) mode. The high spatial and spectral resolution achieved unveils some features of the transport of the metal sputtered atoms and their thermalization. The two groups of thermalized and energetic atoms have been very well separated compared to previous works. Hence, the fitting of the energetic atoms group shows dumping from modified Thompson to Gauss distribution when the product pressure-distance from the target increases. In parallel, sputtered metal transport from the target has been simulated using the Monte Carlo collision (MCC) approach. The direct comparison between numerical and experimental results led to an improved cross section for Titanium - Argon momentum transfer, based on the \textit{ab initio} formulae of the interaction potential derived from noble gases interaction. The numerical parametric study of the angular distribution and cut-off energy for the initial distribution of sputtered atoms steered to a precise characterization of the initial conditions, allowed by the accuracy of experimental data. A very good overall agreement is obtained for measured and calculated AVDFs. The confrontation between measured and modeling results emphasized the major role played by the argon ions not only in the sputtering process but also in the neutral metal transport, by the gas rarefaction near the target. The microscopic description provided by the MCC model clearly reveals different transport regimes: ballistic, diffusive, and back-scattering and brings new insights on the thermalization of sputtered species in the intermediate pressure range.

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Ionized particle transport in reactive HiPIMS discharge: correlation between the energy distribution functions of neutral and ionized atoms

Cited by 5 publications

References 40 publications

Temporal studies of titanium ionised density fraction in reactive HiPIMS with nitrogen admixture

Temporal studies of titanium ionised density fraction in reactive HiPIMS with nitrogen admixture

On the correlation between the TiN thin film properties and the energy flux of neutral sputtered atoms in direct current magnetron discharge

Transition from ballistic to thermalized transport of metal-sputtered species in a DC magnetron

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