Investigations on energy fluxes in magnetron sputter-deposition: implications for texturing and nanoporosity of metals

By means of TRIM.SP Monte-Carlo simulations the energetic and angular distributions of sputtered atoms and reflected argon-neutrals were calculated for sputtering a variety of elemental targets. The power density at the substrate during sputter deposition was measured by a calorimetric method. The combination with measurements of the atomic deposition rate resulted in the determination of the total amount of the energy input per incorporated atom. For low pressure sputtering at 0.4 Pa, the experimental data are well described by contributions due to plasma irradiation, the heat of condensation of deposited atoms, their kinetic energy, and the kinetic energy of the reflected argon-neutrals. For increased pressure, there is an increased contribution of electrons to probe heating. The combination of experimental and a priori calculated data results in empirical rules for the energies of the sputtered and reflected species, which allow an estimate of the energy input during sputter-deposition for every given elemental film material. Strong thermalization of particles at high-pressure deposition resulted in highly porous films with a density below 50% of the bulk material. It is concluded that for circular planar magnetrons and static deposition mode the bombardment of the growing film is inhomogeneous, which results in laterally inhomogeneous crystallographic properties.