Strain distribution near Si/NiSi₂ interface measured by convergent beam electron diffraction

Lattice strain distribution was measured in Si (111) substrates near NiSi₂ islands. Quantitative measurements with high spacial resolution were performed using convergent beam electron diffraction (CBED). Distorted and lower-symmetry CBED patterns were observed up to 2.0 μm from NiSi₂ islands. We show that these CBED patterns can be accounted for by a combination of stress components with different orientations. Stresses were found to be tensile perpendicular to NiSi₂ island edges and compressive parallel to them. In addition, another stress component which had a characteristic orientation was detectable within 0.5 μm of NiSi₂ island edges.