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Topography and tunnelling current mapping of 13, 24 and 53 /spl Aring/ thick SiO/sub 2/ oxides on silicon substrates have been performed by combined AFM (atomic force microscopy) techniques. The topography measurements revealed an increased density of pits on the SiO/sub 2/ surface of the 13 and 24 /spl Aring/ oxide. This gave rise to concerns over technology reliability, and suggested further analysis. Various AFM techniques including Conducting AFM (C-AFM) and Intermittent Contact AFM (IC-AFM) have been used singly and in combination. Commercially available C-AFM tips have been observed to limit the available spatial resolution. Therefore, additional high resolution IC-AFM measurements with sharp silicon probe tips have been made by the incorporation of nanometric orientation marks grown purposely on the surface by anodic oxidation. Good correlation between the topography image of the IC-AFM and the tunneling current mapping of C-AFM in respect to the location of surface features has been observed.

A method is presented to combine the advantages of Conductive Atomic Force Microscopy (C-AFM) and Intermittent Contact AFM (IC- AFM) investigations on the same single area of a SiO/sub 2/ surface. A procedure is shown to overlay precisely different physical AFM images from one single measurement area, by the use of orientation marks (nano marks). Even structures of less than 0.5nm in height with lateral dimensions of a few tenth of a nanometer on a SiO/sub 2/ surface can be located and precisely scanned multiple times by various AFM techniques. With this method the results of different AFM techniques gained by use of different measurement procedures and by different probe tips can be combined to improve the significance of reliability investigations. Artefacts of the measurement procedures and the impact of probe tips may also be studied in more detail.