Surface analysis at the sidewalls of VLSI patterns-limitations and capabilities of spatially resolved Auger electron spectroscopy

Spatially defined excitation by a confined primary electron beam is the basis of conventional scanning Auger microscopy. This method encounters a physical limitation in spatial resolution when it is used for the analysis of sidewall surface of micron‐ and submicron‐sized patterns on VLSI semiconductor devices. The limitation arises from scattered primary electrons, which drastically reduce the analytically usable spatial resolution whenever protruding features of the specimen topography are irradiated by the primary beam. A non‐conventional approach to improve the selectivity for surfaces of special orientation is presented, making use of the characteristic angular distribution of Auger electron emitted from surfaces. It is shown that by an appropriate modification of the angular spectrometer acceptance, the analytical resolution of sidewalls of VLSI patterns can be increased by more than one order of magnitude.