Sub-micron channeling contrast microscopy on reactive ion etched deep Si microstructures

Abstract

High aspect ratio microstructures with compositional inhomogeneity have always been a challenge for broad beam analysis due to the shadowing effect. In the present work, characterization of reactive ion etched (RIE) Si microstructures is carried out using channeling contrast microscopy with a sub-micron beam spot size. An annular detector is used to minimize surface topography effects. The etch damage introduced by the RIE process on Si is determined from channeling measurements. It is found that crystallinity is preserved in the etched trenches, indicating that little damage was inflicted to the crystal lattice by the RIE process. In the axial channeling position, the Si background signal from the substrate is reduced and sensitivity to the light elements detection is increased. This allows quantitative analysis of the composition in the masked regions and etched trenches. The channeled spectrum in the masked regions reveals the presence of a siliconoxyfluoride layer. No F is observed in the etched trenches.