Title

Phase, grain structure, stress, and resistivity of sputter-deposited tungsten films

Authors

Authors

D. Choi; B. C. Wang; S. Chung; X. Liu; A. Darbal; A. Wise; N. T. Nuhfer; K. Barmak; A. P. Warren; K. R. Coffey;M. F. Toney

Comments

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Abbreviated Journal Title

J. Vac. Sci. Technol. A

Keywords

THIN-FILMS; ELECTRICAL-RESISTIVITY; POLYCRYSTALLINE FILMS; ELECTROMIGRATION; MICROSTRUCTURE; TRANSFORMATION; INTERCONNECTS; CONDUCTIVITY; RESISTANCE; SURFACES; Materials Science, Coatings & Films; Physics, Applied

Abstract

Sputter-deposited W films with nominal thicknesses between 5 and 180 nm were prepared by varying the base pressure prior to film deposition and by including or not including sputtered SiO(2) encapsulation layers. X-ray and electron diffraction studies showed that single phase, polycrystalline alpha-W could be achieved in as-deposited films as thin as 5 nm. The stress state in the as-deposited films was found to be inhomogeneous. Annealing resulted in stress relaxation and reduction of resistivity for all films, except the thinnest, unencapsulated film, which agglomerated. In-plane film grain sizes measured for a subset of the annealed films with thicknesses between 5 and 180 nm surprisingly showed a near constant value (101-116 nm), independent of film thickness. Thick-film (>= 120 nm) resistivity values as low as 8.6 mu Omega cm at 301 K were obtained after annealing at 850 degrees C for 2 h. Film resistivities were found to increase with decreasing film thicknesses below 120 nm, even for films which are fully A2 alpha-W with no metastable, A15 beta-W evident. (C) 2011 American Vacuum Society. [DOI: 10.1116/1.3622619]

Journal Title

Journal of Vacuum Science & Technology A

Volume

29

Issue/Number

5

Publication Date

1-1-2011

Document Type

Article

Language

English

First Page

8

WOS Identifier

WOS:000294482200027

ISSN

0734-2101

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