Thermal and oxidation stability of TixW1−x diffusion barriers investigated by soft and hard x-ray photoelectron spectroscopy
File(s)
Author(s)
Type
Journal Article
Abstract
The binary alloy of titanium-tungsten (TiW) is an established diffusion barrier in high-power semiconductor devices, owing to its ability to suppress the diffusion of copper from the metallization scheme into the surrounding silicon substructure. However, little is known about the response of TiW to high-temperature events or its behavior when exposed to air. Here, a combined soft and hard x-ray photoelectron spectroscopy (XPS) characterization approach is used to study the influence of post-deposition annealing and titanium concentration on the oxidation behavior of a 300 nm-thick TiW film. The combination of both XPS techniques allows for the assessment of the chemical state and elemental composition across the surface and bulk of the TiW layer. The findings show that in response to high-temperature annealing, titanium segregates out of the mixed metal system and upwardly migrates, accumulating at the TiW/air interface. Titanium shows remarkably rapid diffusion under relatively short annealing timescales, and the extent of titanium surface enrichment is increased through longer annealing periods or by increasing the bulk titanium concentration. Surface titanium enrichment enhances the extent of oxidation both at the surface and in the bulk of the alloy due to the strong gettering ability of titanium. Quantification of the soft x-ray photoelectron spectra highlights the formation of three tungsten oxidation environments, attributed to WO
Date Issued
2021-05-21
Date Acceptance
2021-04-01
Citation
Journal of Applied Physics, 2021, 129 (19), pp.1-15
ISSN
0021-8979
Publisher
AIP Publishing
Start Page
1
End Page
15
Journal / Book Title
Journal of Applied Physics
Volume
129
Issue
19
Copyright Statement
© 2021 Author(s). This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Appl. Phys. 129, 195302 (2021); https://doi.org/10.1063/5.0048304
Identifier
https://aip.scitation.org/doi/10.1063/5.0048304
Subjects
cond-mat.mtrl-sci
cond-mat.mtrl-sci
physics.comp-ph
01 Mathematical Sciences
02 Physical Sciences
09 Engineering
Applied Physics
Publication Status
Published
Date Publish Online
2021-05-18