Conductance-atomic force microscope characterization of focused ion beam chip repair processes

Measurements of electrical test structure resistances have traditionally served as the primary metrics for judging the merit of new and existing focused ion beam (FIB) chip repair processes. However, more understanding of physical changes occurring on the sample surface after various FIB processes can be gained through the use of a relatively new version of atomic force microscopy (AFM) that employs electrically conductive tips. This technique is referred to as “conducting-AFM,” or C-AFM, and provides spatial mapping of both surface height and electronic conduction simultaneously at each image pixel. A key advantage is that electrical leads and large probing pads are not necessary for determining the electrical behavior of a desired region. Results from C-AFM have also been compared with spectroscopic analysis in order to spatially correlate the elemental composition and electrical conductivity of FIB-induced reaction products.