Reducing the aspect ratio of contact holes by in situ low-angle cross sectioning

Auger analysis of high-aspect ratio contact holes of integrated microelectronic devices is a challenging analytical task. Due to geometrical shadowing the primary electron beam and the energy analyser have not the required direct line of sight to the analysis area simultaneously. To solve this problem sample preparation is needed to flatten the three-dimensional geometry. Here the new approach of in situ low-angle cross sectioning is applied. By this method material gets removed inside the Auger instrument while the sample is sputtered by Ar+ ions at nearly grazing incidence utilizing the edge of a mask, which partly covers the sample. A very shallow bevel with respect to the sample surface is produced. Thus along the bevel contact holes with suitable aspect ratios are available for the Auger analysis.