Strain in silicon below Si3N4 stripes, comparison between SUPREM IV calculation and TEM/CBED measurements

The convergent beam electron diffraction technique (CBED) and SUPREM IV simulation have been applied to determine the lattice strain in a silicon region underlying a Si3N4 stripe. The width and thickness of the stripe are 870 and 194 nm, respectively. These strips are the masks which define the pattern of the LOGOS isolation structure, before thermal oxidation. The silicon nitride film has been deposited onto a (100) silicon wafer through a 21 nm thick pad oxide. The resulting profiles of the components of the stress tensor, converted into strain, along a direction perpendicular to the direction of the stripe, have been deduced from SUPREM IV simulations and compared with the corresponding values, obtained by convergent beam electron diffraction (CBED), performed in different points of TEM cross sections of the same structure. It has been found that a suitable choice of the SUPREM IV parameters is needed in order to fit the experimental data to the simulated ones.