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Proximity Effect in the Low Pressure Chemical Vapor Deposition of Tungsten.

Published online by Cambridge University Press:  25 February 2011

N. Lifshitz
N. Lifshitz*
Affiliation:
AT&T Bell Laboratories, Murray Hill, New Jersey 07974
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Abstract

The self-limiting effect during Low Pressure Chemical Vapor Deposition of tungsten is manifested by a sudden interruption of the reduction of tungsten hexafluoride WF6 by silicon, so that only very thin (self-limited) films of silicon-reduced tungsten can be grown. It has been shown that the self-limiting effect is caused by formation of the non-volatile subfluoride WF4. The temperature dependence of the self-limiting thickness of the tungsten films grown in a hot-wall reactor exhibits a characteristic maximum at temperatures near 350°C, which indicates that at this temperature the rate of formation of WF4 is lower than at temperatures above and below. In the present paper we attempt to explain this peculiar dependence. We suggest a mechanism responsible for formation of the blocking agent WF4. We demonstrate that the presence of a hot tungsten surface is essential for the strong self-limiting effect. This leads us to the discussion of the proper selection of the reactor type (hot-wall vs. cold-wall) for different process requirements.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 131: Symposium E – Chemical Perspectives of Microelectronic Materials I , 1988 , 623
Copyright
Copyright © Materials Research Society 1989

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References

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