Nanoscale electrical characterization of HfO/sub 2//SiO/sub 2/ MOS gate stacks with enhanced-CAFM

The conduction and dielectric breakdown (BD) of an ultra-thin HfO/sub 2//SiO/sub 2/ gate stack is studied at the nanoscale. With this purpose, an enhanced conductive atomic force microscope (a CAFM with extended electrical performance) has been developed. Using this new set up, different conduction modes have been observed before BD, which can be masked during standard tests. The study of the BD spots has revealed that, as for SiO/sub 2/, the BD of the stack leads to modifications in the topography images and high conductive spots in the current images.