A Method for Evaluating the Thickness of Ultrathin Films

A method for determining the thickness of ultrathin (<10 nm) films using an atomic-force microscope is described. Films were deposited onto a porous glass substrate that has smooth surface areas between the pores when the flow of the evaporated material incident on the substrate is at an angle of 20°–30° with respect to the normal to its surface. In order to obtain pores with sharp edges, the substrate surface was preliminarily sputtered by an oxygen ion beam directed at an angle of 90° to this surface. Images of such films obtained using the atomic-force microscopy technique clearly resolve the position of the pore edge–film boundary, making it possible to evaluate the film thickness by the height of the step between the pore edge and the by surface in the cross section of the surface topography.