Strain characterisation of shallow trench isolation structures on a nanometer scale by convergent beam electron diffraction

The convergent beam electron diffraction (CBED) technique of transmission e lectron microscopy (TEM) has been applied to [110] cross-sections of shallo w trench isolation structures in silicon, in order to evaluate the strain f ield distribution in 0.22 mum wide active areas. Different spot sizes (1 an d 10 nm) and sample temperatures (room temperature with energy filtering, l iquid nitrogen cooling without filtering) have been employed. It has been f ound that the regions of the active area closer than about 100 nm to the pa doxide/substrate interface can be analysed only by using a 1 nm spot size. Moreover, the use of an energy filter to reduce the inelastic scattering im proves the contrast of the diffraction lines in the CBED pattern, thus allo wing the analysis to be performed at room temperature. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.