Bias dependent contrast mechanisms in EBIC images of MOS capacitors

Defects and inhomogeneities in the electrical properties of metal oxide sil icon capacitors are analyzed by scanning electron microscopy, using the ele ctron beam induced current technique (MOS/EBIC). All capacitors were analyz ed in their as-fabricated or prebreakdown condition. The collected signals and image contrast are found to be highly dependent on the gate-to-substrat e bias applied during MOS/EBIC examination, and this bias-dependence is sho wn to be correlated with the nature and physical location of the defect. Sp ecific MOS defects were selected for this study according to their position in the substrate, in the oxide, or at the Si/SiO2 interface. Substrate def ects examined were misfit dislocations in epitaxial Si(Ge) on Si. Interfaci al inhomogeneities included thermally oxidized, reactive ion etched (RIE) S i surfaces, and SiO2 precipitates or "D-defects" which extend to meet the S i surface. Oxide layer inhomogeneities were also detectable which exhibited a strong contrast dependence on the oxide electric field strength. (C) 199 9 The Electrochemical Society. S0013-4651(98)06-085-6. All rights reserved.