Analysis of the energy input during wire coating from a cylindrical magnetron source

In order to deposit thin films on a substrate several techniques can be used, e.g. chemical vapour deposition, atomic layer deposition or sputter deposition, depending on their specific advantages and disadvantages due to the related application. A significant parameter is the energy incident upon the substrate by the specific technique, especially when the heat capacitance of the substrate is low. Within this paper we analyse the energy transported into a thin wire (few 10 μm in diameter) during a dynamic inline aluminium sputter process in a cylindrical magnetron source. The evoked heating is important for the tensile strength of the wire and uniformity of the sputtered layer. Therefore, mathematical models were created to estimate the energy input into the wire supported by monte-carlo-simulations of the sputtering process using the TRIM-simulation (Transport and Range of Ions in Matter). Measurements with a Langmuir probe and the corresponding deposition rate were used to quantify these models, showing that at an aluminium coating process of a gold wire, the significant energy input is only due to electrons and ions of the processing gas (argon). Using the heat equation based on the sputtering apparatus' parameters, it was also possible to determine the energy input into the wire with in situ electrical resistance measurements. Both methods did show similar results, whereby the resistance results were more stable. The determined energy input made it possible to calculate the temperature profile during the wire-coating process which can be useful for estimations about film diffusion and process optimisation.

► Comparison of two models for the energy input of a sputtering process.
► Main energy contribution due to electrons and ions.
► Evaluation of a dynamic thermal profile based on the energy input.