Lateral thickness inhomogeneities of Cu, Ti and Ag ion-beam-assisted deposition coatings on three-dimensional substrates studied by proton-induced X-ray emission

Abstract

In the present study, thickness inhomogeneities of ion-assisted coatings under off-normal ion and atom incidence were studied on three-dimensional substrates, by means of proton-induced X-ray emission and Rutherford backscattering spectrometry measurements. A comparison was made between the thickness loss in ion-beam-assisted deposition (IBAD) and in the decoupled process, i.e. ion irradiation after vapour deposition, under the same deposition and irradiation conditions. The resulting angular-dependent dynamic and static etch rates were evaluated for the three systems: Cu, Ti and Ag on technical, half-cylindrical Al substrates. The results show that large differences in the sputter efficiency occur under perpendicular ion incidence. This can be explained by topographical changes, as can be seen from REM pictures. The normalized angular-dependent etch rates show remarkable differences of up to 400%. The IBAD coatings exhibited stronger increases in the grazing angles and higher maximum yields than did the pure ion-bombarded coatings. A comparison of the normalized static yields with experimental data from the literature showed good agreement, whereas the dynamic yields differed from those obtained by Monte Carlo calculations with the TRIM-DYN code.