Sn/Pb ratio variation in spherical structures deposited on silicon surface using plasma focus

The deposition of Sn and Pb elements on top of Si surface was realized using plasma focus device. Due to the special characteristic of this type of plasma, the silicon substrate is heated by the bombardment of plasma ions, before the deposition of these elements sputtered from the anode. The deposition of the two elements was found to be influenced by substrate-anode distance as a consequence of surface heating. It was found that the relative amounts between the two deposited elements was not the same as their original ratio in the anode before sputtering. The ratio between Sn and Pb varies with increasing depth into the SnPb deposited on the Si substrate. Additionally, the size of micro spherical structures formed on the surface affected the ratio of the two deposited elements. The variation of the ratio is explained as result of deposition/evaporation competition influenced by the surface heating.