Surface Defects and Local Strain in Polished Silicon by Transmission Electron Microscopy

Abstract

Surface defects and local strain in polished silicon were characterized by cross-sectional transmission electron microscopy (XTEM) and convergent beam electron diffraction (CBED). Dislocations are introduced from the surface by polishing with diamond slurry, and their main slip system was found to be 1/2{111}. The depth of the dislocation-introduced zone deepens with increasing diamond particle size, however, the density of dislocations is fairly high for materials polished with particles of small size. This is because the stress between particle and surface increases with increasing particle size, and the particle density increases with decreasing particle size. Local strain remains up to a depth of 1-1.5 µ m beneath the surface for samples polished with 0.5 to 6 µ m diamond slurry. This residual stress is distributed approximately 1 µ m below the dislocation-introduced zone.