Topography and microstructure of Al films formed under various deposition conditions

Abstract

Al films were vapor deposited in high vacuum onto SiO2/Si substrates at various substrate temperatures (T) and deposition rates (R) which ranged, respectively, from 24 to 250 °C and from 2 to 90 Å/s. The films were examined by scanning electron microscopy (SEM) and showed systematic variations in topography. Hillock formation occurred only on films deposited at low substrate temperatures and low deposition rates. Films which were deposited at high substrate temperatures and low deposition rates had rough surfaces. The high deposition rate films were smooth. Transmission electron microscopy (TEM) showed that the average grain size and the widths of the grain size distributions increased as the substrate temperature increased. The topographical and microstructural results are plotted on ln R versus 1/T graphs which thus show in a convenient format how these film properties depend upon supersaturation.