ELLIPSOMETRIC INVESTIGATIONS DURING TITANIUM DEPOSITION IN A HOLLOW-CATHODE ARE EVAPORATION DEVICE

Thin Ti films (less than or equal to 200 nm) were grown on Si wafers ( 100) by means of a hollow cathode are evaporation device (HCAED). The layer growth was monitored in situ by monochromatic ellipsometry. Spec troscopic ellipsometry was used to characterize the as-deposited layer s. The results obtained by ellipsometry have been compared with other thin film diagnostic techniques, especially with Rutherford backscatte ring spectroscopy. Modelling of the ellipsometric measurements shows t hat the film density is strongly influenced by the deposition conditio ns. The RBS analysis supports the results of ellipsometric studies. Th ere exists a strong relation between the energy of the Ti ions strikin g the substrate and the layer density. Nucleation is described by a co lumnar microstructural development during the early stage of the growt h. The bulk grows homogeneously beneath a surface roughness layer whic h is a consequence of incomplete coalescence of the initial nuclei. Th e surface quality of the substrate influences the early stage of the f ilm growth. If a shutter above the titanium vessel is used, the layer grows inhomogeneously. The density gradients are caused by the increas ing evaporation rate because of thermal stabilization of the HCAED aft er opening the shutter.