Why is it possible to detect doped regions of semiconductors in low voltage SEM: a review and update

M. El-Gomati, F. Zaggout, H. Jayacody, S. Tear, K. Wilson

Research output: Contribution to journalSpecial issue

Abstract

There is an urgent need for fast, non-destructive and quantitative two-dimensional dopant profiling of modern and future ultra large-scale semiconductor devices. The low voltage scanning electron microscope (LVSEM) has emerged to satisfy this need, in part, whereby it is possible to detect different secondary electron yield values (brightness in the SEM signal) from the p-type to the n-type doped regions as well as different brightness levels from the same dopant type. The mechanism that gives rise to such a secondary electron (SE) contrast effect is not fully understood, however. A review of the different models that have been proposed to explain this SE contrast is given. We report on new experiments that support the proposal that this contrast is due to the establishment of metal-to-semiconductor surface contacts. Further experiments showing the effect of instrument parameters including the electron dose, the scan speeds and the electron beam energy on the SE contrast are also reported. Preliminary results on the dependence of the SE contrast on the existence of a surface structure featuring metal-oxide semiconductor (MOS) are also reported.
Original languageEnglish
Pages (from-to)901-911
Number of pages11
JournalSurface and interface analysis
Volume37
Issue number11
Early online date31 Oct 2005
DOIs
Publication statusPublished - Nov 2005

Bibliographical note

Special Issue: Proceedings of NIST workshop on Modeling Electron Transport for Applications in Electron and X-Ray Analysis and Metrology (November 8–10, 2004)

Keywords

  • LVSEM
  • dopants
  • semiconductors
  • contrast

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