First we want see how the target atoms going into the gas phase. Sputtering is a momentum transfer process. Approximately 95 % of incident energy goes into the target top 10 Å layers and the target need to be cooled. This process can be modeled using hard sphere collisions. 5% of incident energy is carried off by target atoms and approximately 1 to 2% of the atoms in the target are ejected as ions and electrons (T and T⁺). These electrons are useful in keeping the plasma going. Target atoms come off with a non-uniform distribution. The process can be characterized by sputter yield (S) and it is the number ejected / number incident ions. S depends on mass and binding energy of the target material, mass and energy of the sputtering gas, and the angle of incident. The sputter yield is found maximum at about 20-30 degrees from glancing. Usually there exists a threshold energy exists and typical values of S about 1-10. In sputtering, unlike in evaporation, the composition of alloy in deposited film is approximately the same as alloy in target. This is because of the slow diffusion mixing of solids in case sputtering compared to rapid mixing in evaporation.

During the transport of atoms of to substrate, they pass through Ar gas and plasma environment. Typically one Ar⁺ ion for every 10,000 Ar neutrals results and the electrons in plasma collide with Ar neutrals to form ions and additional electrons. Target atoms collide with Ar atoms, Ar⁺ ions and electrons and typically lose 1-10 eV energy. The movement can be considered as random walk "diffusion" through gas. This is not a line of sight process and one can coat around corners. During the deposition, not only target atoms, but also the ions/electron can impinge on substrate. The growth of deposited films is enhanced by these energetic particles as well as by substrate heating to100 - 200°C.