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Collisionality-Controlled Transport of Sputtered Atoms in Argon: A Reproducible Monte Carlo Study Across Six Target Materials |
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PP: 203-210 |
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doi:10.18576/ijtfst/150207
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Author(s) |
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Abdelkader Bouazza,
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Abstract |
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| Gas-phase transport between a sputtering target and a substrate determines how much of the nascent flux survives, how strongly it thermalizes and with what angular distribution it arrives. In this work, a reproducible Monte Carlo campaign is used to quantify these coupled effects for Cu, Al, Ag, Ge, Si and Te sputtered into Ar at 300 K. The baseline design covers four pressures (0.3, 0.5, 0.8 and 1.0 Pa), four target–substrate distances (8, 12, 16 and 20 cm) and 20,000 launched particles per condition, giving 1.92 million trajectories. Initial energies are drawn from a truncated Sigmund–Thompson distribution, emission directions follow a cosine law, and emission points are distributed uniformly over the target area. Free flights are sampled from an energy-dependent effective transport cross section, and collisions are treated with elastic two-body hard-sphere kinematics. The computed observables are substrate transmission, collision counts, arrival-energy percentiles, high-energy fractions, radial spreading and incident angle. The median arrival energy decreases monotonically with both pressure and distance for all six materials, whereas the arithmetic mean can remain strongly influenced by a sparse energetic tail. Over the investigated window, P·L is a useful empirical collisionality coordinate, with median- energy regression R2 values of 0.792–0.867 and material-specific slopes from −13.75 to −29.22 eV/(Pa m). Independent three-seed calculations and a 486-case sensitivity campaign show that the qualitative transport trends are robust, whereas absolute values depend on the adopted effective cross-section parameters. The framework therefore offers a transparent and reproducible basis for comparing species-dependent thermalization and transmission; it characterizes the arriving flux and is not intended as a direct predictor of film morphology or thickness. |
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