10We report in this work the investigation of the transport behavior of Ti neutral atoms 11 sputtered in reactive high power impulse magnetron sputtering (R-HiPIMS) device 12 used for TiN coating deposition. The time resolved tunable diode laser induced 13 fluorescence (TR-TDLIF), previously developed to study the transport of tungsten 14 atoms, was improved to measure Ti neutral atoms velocity distribution functions. We 15 find that the TR-TDLIF signal has to be fitted using three Gaussian distributions, 16 corresponding to the energetic (EN), thermalized (TH) and quasi-thermalized (QTH: 17 TH atoms with non-zero mean velocity) atoms populations. Then, the ability to 18 distinguish populations of atoms and to determine their corresponding deposited flux 19 and energy may be of great interest to control film properties as desired for targeted 20 applications. From the fitting, the vapor transport parameters (flux and energy) are 21 calculated and studied as function of distance from the target, pressure and percentage 22 of nitrogen in Ar/N2 gas mixture. The study focuses on the effect of added nitrogen on 23 the transport of sputtered atoms. 24 Keywords: time resolved tunable diode laser induced fluorescence, reactive 25 magnetron sputtering, high power impulse magnetron sputtering (HiPIMS), atoms 26 velocity distribution function, transport of sputtered atoms, titanium, nitrogen 27 I. Introduction 28 Since the 1970s, magnetron sputtering (MS) process has been developed for the growth of 29 thin films by physical vapor deposition (PVD) [1]. The developments of conventional reactive 30 direct current (R-dcMS) and radiofrequency (R-rfMS) magnetron sputtering methods allow 31 the deposition of a wide range of thin films of materials such as metals, oxides, nitrides, 32 ceramics, etc. [2]. Consequently, MS is a widely used deposition technology in many 33 industrial applications.34 2 In conventional magnetron sputtering discharges, sputtered species are mainly emitted by 35 the cathode as neutral particles and ions of the sputtered material do not contribute 36 significantly to the deposition process. Ionized Physical Vapor Deposition (IPVD) reactors 37have then been developed since the 1990s to improve the quality of deposited films in terms 38 of mechanical properties (higher density, reduced porosity, better resistance to corrosion) and 39 of conformity for deposition on complex substrate geometry [3][4][5][6][7][8]. The main goal of IPVD is 40 to ionize a fraction of neutral species sputtered from the magnetron target in order to transfer 41 potential energy to ions, and to collimate and control the obtained ion particle fluxes by 42 applying a negative bias voltage to the substrate. IPVD reactors consist of a magnetron 43 discharge assisted by an additional plasma source, located in the area between the substrate 44 and the magnetron cathode, which ionizes the sputtered vapor flowing from the magnetron. 45Reactors using helicon [9], electron cyclotron resonance (ECR) coupled discharge [10] or 46 microw...

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.