Effect of ion collisions on Langmuir probe measurements in Ti-N deposition by unbalanced magnetron sputtering

Langmuir probe measurements are a useful tool to evaluate the influence of plasma parameters on the mechanical properties of sputtered thin films. Ti-N is deposited by unbalanced magnetron sputtering at room temperature. The plasma parameters are determined by a cylindrical Langmuir probe. The deposition parameters are correlated to the plasma characteristics through the determination of the electron mean free path. The ion density is calculated according to the collisional Zakrzewski and Kopiczynski correction to the Laframboise model extended to a two-component gas. In order to evaluate the ion bombardment per condensing atom, the chemical composition and the density of the deposited thin films are determined by accurate electron probe microanalysis. The calculations show how the action of ion-atom collisions on ion collection by the probe affects the evaluation of the ion bombardment.