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Quantitative Dopant Profiling in the SEM including surface states.
|Augustus K. Chee 1, Colin J. Humphreys 1, Conny Rodenburg 2
1. University of Cambridge, Department of Materials Science and Nanoscience Centre, Pembroke Street, Cambridge CB2 3QZ, United Kingdom
Two-dimensional dopant mapping using secondary electrons (SEs) in a FEG-SEM is a potentially useful technique for studying dopant distributions in semiconducting materials at high spatial resolution. A novel implementation of an attachment to the through-the-lens detector has enabled quantification of dopant profiles to be developed more readily from SE imaging, allowing a non-destructive and rapid in-situ characterisation method of semiconductor devices. However, the reason that it has not yet found widespread application is the lack of an accurate and robust quantification procedure. Although it is known that secondary electron dopant contrast observed across a p-n junction is a function of the built-in potential across the junction, surface band-bending and external local fields (patch fields) above the specimen, the lack of understanding on the respective contributions from all these factors has hampered accurate quantification. To analyse the problem, we have used detailed computer modelling to investigate the effects of surface states and doping concentrations as well as doping feature geometries, on the surface band-bending and external patch fields. We have tested the validity of our calculations against experimentally measured secondary electron energy spectra. The methodology described in this work will help to enable accurate quantification in the dopant mapping of semiconductors in the SEM.
Presentation: Oral at E-MRS Fall Meeting 2007, Symposium J, by Augustus K. Chee
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-14 05:25 Revised: 2009-06-07 00:44