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Effect of Surface Iron on Gate Oxide Integrity and its Removal from Silicon Surfaces

Published online by Cambridge University Press:  21 February 2011

Heungsoo Park ,
C. R. Helms ,
Daehong Ko ,
M. Tran  and
B. B. Triplett
Heungsoo Park
Affiliation:
Solid State Electronics Laboratory, Stanford University, Stanford, CA 94305
C. R. Helms
Affiliation:
Solid State Electronics Laboratory, Stanford University, Stanford, CA 94305
Daehong Ko
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305
M. Tran
Affiliation:
Intel Corporation, Santa Clara, CA 95052-8125
B. B. Triplett
Affiliation:
Intel Corporation, Santa Clara, CA 95052-8125
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Abstract

We found that effective removal of iron from silicon surfaces requires at least three steps (plus rinses), one of which must be an hydrofluoric acid solution. Even for wafers without intentional contamination, the chemical cleans before oxidation can strongly affect the photoconductivity recombination lifetime of the wafers: a very low lifetime for silicon wafers with SC1-last surfaces, a relatively high lifetime for silicon wafers with SC2-last surfaces, and a high lifetime for silicon wafers with HF-last surfaces. We also found that precipitates and stacking-fault like defects caused by iron contamination were formed underneath thermally-grown silicon oxide. We believe that the precipitates were iron silicides formed during the oxidation of iron-contaminated silicon.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 315: Symposium Y – Surface Chemical Cleaning and Passivation for Semiconductor Processing , 1993 , 353
Copyright
Copyright © Materials Research Society 1993

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References

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