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Microanalysis of Tungsten Silicide/Polysilicon Interface: Effectiveness of in Situ Rie Clean on Removal of Native Oxide

Published online by Cambridge University Press:  21 February 2011

Ronald S. Nowicki
Affiliation:
Genus, Incorporated, Mt. View, CA 94043
Patrice Geraghty
Affiliation:
Genus, Incorporated, Mt. View, CA 94043
David W. Harris
Affiliation:
Charles Evans Associates, Redwood City, CA 94063
Gayle Lux
Affiliation:
Charles Evans Associates, Redwood City, CA 94063
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Abstract

The presence of a thin (10-30Å) oxide (“native oxide”) layer on a silicon surface prior to the deposition of another film on that surface can contribute todifficulties with subsequent device processing steps, e.g. contact metallization and hightemperature annealing or oxidation. Thus, the in situ process capability of “native oxide” removal affords an advantage over the conventional method of aqueous hydrofluoric acid cleaning prior to a film deposition step. This study describes such a technique, in which an in situ pre-deposition clean with C2F6 gas, using reactive ion etching (RIE) prior to tungsten silicide deposition, is employed. This technique allows post-silicide deposition high-temperature heat treatment and wet oxidation without loss of film adhesion or other obvious degradative effects. We also report the useof Secondary Ion Mass Spectrometry (SIMS) to show that this procedure has een effective in the removal of the oxide layer prior to silicide deposition. This study includes definition of the RIE etch parameters which provide acceptable etch selectivity of the oxideto silicon, and avoidance of excessive fluoropolymer formation on the silicon surface.

Type
Research Article
Copyright
Copyright © Materials Research Society 1990

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