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Cleaning Process Optimization in a Gate Oxide Cluster Tool Using an in-Line XPS Module

Published online by Cambridge University Press:  10 February 2011

Barbara Froeschle
Affiliation:
STEAG AST elektronik GmbH, Daimlerstrasse 10, D-89160 Domstadt, Germany
Frédérique Glowacki
Affiliation:
STEAG AST elektronik GmbH, Daimlerstrasse 10, D-89160 Domstadt, Germany
Anton J. Bauer
Affiliation:
Fraunhofer-Institut fuer Integrierte Schaltungen, Bauelementetechnologie, Schottkystrasse 10, D-91058 Erlangen
Igor Kasko
Affiliation:
Fraunhofer-Institut fuer Integrierte Schaltungen, Bauelementetechnologie, Schottkystrasse 10, D-91058 Erlangen
Richard Oechsner
Affiliation:
Fraunhofer-Institut fuer Integrierte Schaltungen, Bauelementetechnologie, Schottkystrasse 10, D-91058 Erlangen
Claus Schneider
Affiliation:
Fraunhofer-Institut fuer Integrierte Schaltungen, Bauelementetechnologie, Schottkystrasse 10, D-91058 Erlangen
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Abstract

A cleaning process using anhydrous HF (AHF)/methanol and ozone was carried out in a STEAG AST Vapor Phase Cleaning module (VPC). This module was integrated in a state-of-theart cluster tool also consisting of a STEAG AST Rapid Thermal Oxidation module (RTO). To investigate the properties of silicon after cleaning a novel in-line XPS module was integrated into the gate oxide cluster. Measurements of fluorine, carbon, and oxygen contamination in the range from 0.01 to 1 monolayers on cleaned wafer surfaces and on regrown oxides (< 0.5 nm) have been performed and used for rapid optimization of the cleaning procedure. The in-line integration enabled measurements without exposing the wafers to atmosphere thus avoiding oxidation or contamination of the wafer surfaces. To demonstrate the feasibility of this cluster tool for advanced gate dielectric formation, 4.0 nm thin oxide was grown directly after the cleaning in the RTO module without breaking the vacuum. Time dependent dielectric breakdown results for oxides pre-oxidation-cleaned in AHF, and in AHF followed by ozone were compared to a reference sample without any dry pre-oxidation cleaning. It could be shown, that the cleaning in AHF with a subsequent ozone step at 200°C under UV light lead to improved breakdown characteristics compared to AHF/methanol cleanings without such subsequent ozone/UV step or conventional wet cleaning using HF-Dip.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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