Near-field Scanning Optical, Atomic Force, Scanning Resistance and uv Confocal Microscopy in the Failure Analysis of ULSIs Produced with the Most Advanced Sub-Quarter Micron Design Rules

Reflection near-field scanning optical microscopy (NSOM) images are presented of static random access memory chips which have undergone a chemical mechanical polishing operation. These images are compared to atomic force microscopy images on the one hand and these images show no topography on these essentially flat samples. The images are also compared to deep uv confocal microscope images at 248 nm and the associated NSOM scan clearly shows considerably higher feature definition and resolution. In addition, it is shown that the same NSOM/AFM cantilevered optical fiber can be used to record an image of the resistivity of the titanium salicide layer of this chip. Finally, it is demostrated that unique new force sensing probes can be designed for chip failure analysis and inspection using the methodologies that have been refined for producing near-field optical probes.