Real-space Strain Mapping of Soi Features Using Microbeam X-ray Diffraction

Synchrotron-based X-ray microbeam measurements were performed on silicon-on-insulator (SOI) features strained by adjacent shallow-trench-isolation (STI). Strain engineering in microelectronic technology represents an important aspect of the enhancement in complementary metal-oxide semiconductor (CMOS) device performance. Because of the complexity of the composite geometry associated with microelectronic circuitry, characterization of the strained Si devices at a submicron resolution is necessary to verify the expected strain distributions. The interaction region of the SOI strain extended at least 25 times the SOI film thickness from the STI edge. Regions of 65 nm thick SOI less than 3 μm wide exhibited an overlap in the strain fields because of the surrounding STI. Microbeam mapping of arrays containing submicron SOI features and embedded STI structures revealed the largest out-of-plane strains because of the close proximity of superimposed strain distributions induced by the STI.