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Characteristics of Selective Lpcvd W Films By Silicon Reduction

Published online by Cambridge University Press:  28 February 2011

R. V. Joshi  and
D. A. Smith
R. V. Joshi
Affiliation:
IBM, T.J. Watson Research Center Yorktown Heights, New York 10598
D. A. Smith
Affiliation:
IBM, T.J. Watson Research Center Yorktown Heights, New York 10598
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Abstract

The characteristics of Selective LPCVD tungsten films produced by silicon reduction of tungsten hexafluoride are presented. The tungsten films deposited using Si(100), Si(111) and polysilicon undoped and doped substrates are analyzed by X-RAY, TEM, RBS, AES, SIMS and SEM. The as deposited bcc tungsten films are polycrystalline with a grain size 80 - 100Å. The effect of annealing temperature and time on the crystal structure of films was studied. Tungsten reacts to form tungsten silicide at 600°C. The silicide grain size is of the order of 100 - 200Å at 600°C and increases gradually to 400 - 500Å at 1000°C. The oxygen impurities in the film retard the silicide formation further at 1000°C. Silicon from the substrate out-diffuses to the film surface and reacts with the presence of oxygen impurities in the annealing ambient to form Si-O at 1000°C. As deposited film resistivities of 130-140 micro-ohm-cm are achieved reproducibly and reach 60-70 micro-ohm-cm after 1000°C annealing in nitrogen or argon ambient. The impurities H, C, O and F are found in the as deposited films.

Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 71: Symposium F – Materials Issues in Silicon Integrated Circuit Processing , 1986 , 309
Copyright
Copyright © Materials Research Society 1986

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References

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