Strained growth behavior of selective silicon epitaxy in confined structures

We have studied the strained growth behavior of selective silicon epitaxial growth (SEG) on windows defined by silicon nitride block/spacer and field oxide grown by local oxidation of silicon (LOCOS). The interface having a narrow width of SEG windows shows lots of stress fringes-caused by thermal stresses developed between nitride and silicon SEG layer. In the case of LOCOS-type field oxide, initial facet plane is very distinctively driven by vertical (110) facets due to the strain dependent anisotropic migration of silicon atoms that tend to favor upwards migration away from the interface for increasing strain relaxation. The stacking sequence of atoms in these vertical facets is likely to make stacking faults. We also observed the oxide undercutting and silicon encroachment into undercut area during SEG process. The presence of the oxide undercut implies detrimental effects such as the increase of junction leakage current.