A study of gate-all-around transistors by electron tomography

Abstract

Gate-all-around (GAA) SiGe nanowire transistor structures have been studied using high angle annular dark field (HAADF) STEM tomography. Sample preparation has been optimized by isolating single devices in needle-shaped specimens, using annular milling in the focused ion beam (FIB). Using this technique, images can be acquired over a tilt range up to +/- 80°. Two dimensional simulations are used to establish the optimum orientation for devices in this sample geometry. Tomograms are presented, and the impact of the "missing wedge" on the reconstruction is assessed, again with reference to two dimensional simulations. © 2009 American Institute of Physics.