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Non-Contact Mapping of Fe Contamination in Oxidized Si Wafers with Sensitivity in Part-Per-Trillion Range

Published online by Cambridge University Press:  15 February 2011

Jacek Lagowski
Affiliation:
Center For Microelectronics Research, University of South Florida, Tampa, FL 33620
Piotr Edelman
Affiliation:
Semiconductor Diagnostics, Inc., 6604 Harney Rd, Tampa, FL 33610
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Abstract

Traces of iron contamination as minute as one part per trillion atom fraction can be detrimental to the gate oxide integrity of the very thin oxides, 10 nm or less, used in the most advanced ICs. Fe contamination monitoring discussed in this paper is done with the surface photovoltage (SPV) technique which measures the minority carrier diffusion length, L, before and after the recombination efficiency of iron is enhanced by optical splitting of the iron-boron pairs. Wafer-scale mapping of iron gives fingerprints of contaminating tools and processes. In this paper, we also present an extension of SPV to oxidized wafers. In the past, such measurements were rendered impossible due to optical interference in the SiO2.

The apparatus incorporates a whole wafer, optical Fe activation station and it provides whole wafer maps of Fe in a total time of 6 to 20 minutes per wafer, depending on probing density.

Type
Research Article
Copyright
Copyright © Materials Research Society 1996

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