Local lattice strain measurements in semiconductor devices by using convergent-beam electron diffraction

We examined the lattice strain distribution around local oxidation of silic on (LOCOS) in a semiconductor device by using highly accurate (1.8 x 10(-4) standard deviation) convergent-beam electron diffraction (CBED) at a nanom eter-scale spatial resolution (10 nm in diameter). The nanometer-scale meas urement was done by reducing the elastic relaxation using a thick (about 60 0 nm) sample and by removing the inelastically scattered electrons by means of an electron energy filter. A highly accurate measurement was achieved t hrough the analysis of higher-order Laue zone (HOLZ) patterns using the lea st-squares fitting of HOLZ line intersection distances between the observat ions and calculations. Our examination showed that the LOGOS structure gave singularities in strain distributions at the field edge. That is, compress ive strain exists in both the vertical and horizontal directions of the sub strate, and the shear strain increased there. Most notably, two-dimensional measurements revealed that the singularity of the normal strain in the hor izontal direction of the substrate generated at the field edge propagated i nto the substrate. (C) 2000 Elsevier Science B.V. All rights reserved.