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Anisotropic Reactive Ion Etching of Submicron W Features In CF4 or SF6 Plasmas

Published online by Cambridge University Press:  26 February 2011

T. R. Fullowan ,
F. Ren ,
S. J. Pearton ,
G. E. Mahoney  and
R. L. Kostelak
T. R. Fullowan
Affiliation:
AT&T Bell Laboratories, Murray Hill, NJ
F. Ren
Affiliation:
AT&T Bell Laboratories, Murray Hill, NJ
S. J. Pearton
Affiliation:
AT&T Bell Laboratories, Murray Hill, NJ
G. E. Mahoney
Affiliation:
AT&T Bell Laboratories, Reading, PA
R. L. Kostelak
Affiliation:
AT&T Bell Laboratories, Murray Hill, NJ
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Abstract

Anisotropie RIE etching of Tungsten (W) in a low voltage CF4 or SF6 plasma while achieving features as small as 0.50 μm is demonstrated using Titanium (Ti) as an etch mask. For reasons of reliability and tolerance to high temperature processing techniques, W can be a desirable contact metal in microelectronics fabrication. Due to its high melting point (3400°C) it is not practical to evaporate W contacts using conventional liftoff photolithography methods. Therefore pattern transfer of sputtered W must be performed by plasma etching using some type of mask. In III-V materials systems, a Fluorine based plasma is desirable due to its high selectivity for W over semiconductor materials. The problem is that when using conventional photoresist masks, W does not etch anisotropically. Therefore critical feature dimensions (which are sub-micron for FET gates) and vertical profiles cannot be successfully transferred to the underlying W. However by using a Ti mask during the CF4 or SF6 plasma etch, TiF4 is produced on the sidewalls of the W inhibiting any horizontal etch. The Ti mask can be removed selectively after etching of the W is complete. Using a Ti mask to etch W ensures excellent pattern transfer of device dimensions even at very low bias voltage.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 240: Symposium E – Advanced III-V Compound Semiconductor Growth, Processing and Devices , 1991 , 315
Copyright
Copyright © Materials Research Society 1992

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References

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