Journal of the Electrochemical Society, Vol.146, No.4, 1529-1535, 1999
Bias dependent contrast mechanisms in EBIC images of MOS capacitors
Defects and inhomogeneities in the electrical properties of metal oxide silicon capacitors are analyzed by scanning electron microscopy, using the electron beam induced current technique (MOS/EBIC). All capacitors were analyzed in their as-fabricated or prebreakdown condition. The collected signals and image contrast are found to be highly dependent on the gate-to-substrate bias applied during MOS/EBIC examination, and this bias-dependence is shown to be correlated with the nature and physical location of the defect. Specific MOS defects were selected for this study according to their position in the substrate, in the oxide, or at the Si/SiO2 interface. Substrate defects examined were misfit dislocations in epitaxial Si(Ge) on Si. Interfacial inhomogeneities included thermally oxidized, reactive ion etched (RIE) Si surfaces, and SiO2 precipitates or "D-defects" which extend to meet the Si surface. Oxide layer inhomogeneities were also detectable which exhibited a strong contrast dependence on the oxide electric field strength.