Published January 2021 | Version v1
Journal article Metadata-only

Tungsten passivation layer (WO3) formation mechanisms during chemical mechanical planarization in the presence of oxidizers

Creators

  • 1. Department of Chemical Engineering, National Institute of Technology Karnataka, Surathkal, Mangalore 575025 (India)
  • 2. Department of Materials Science and Chemical Engineering, Hanyang University ERICA, Ansan 15588 (Korea, Republic of)
  • 3. Department of Smart Convergence Engineering, Hanyang University ERICA, Ansan 15588 (Korea, Republic of)

Description

Highlights: • Tungsten (W) CMP mechanism in the presence of Fe(NO3)3, H2O2, and a mixture thereof were studied. • W slurry with mixed oxidants of Fe(NO3)3 and H2O2 showed a high W polishing rate. • X-ray photoelectron spectroscopy (XPS) confirmed higher WO3 content in mixed oxidants. • Slurry with single H2O2 mainly etched the W surface rather than passivating it. • Presence of OH, WO3 content, and corrosion current showed a similar trend with the W polishing rate. Effects of single and mixed oxidants of Fe(NO3)3 and H2O2 containing acidic silica slurries were studied to investigate the mechanism of tungsten (W) chemical mechanical planarization (CMP). The W polishing rate obtained from the CMP test depicted high W polishing rate in the presence of mixed oxidants of Fe(NO3)3 and H2O2 as compared to a single oxidant of either H2O2 or Fe(NO3)3. The formation of a passive layer of tungsten oxide (WO3) and W dissolution could be the reason for these results as confirmed by XPS. Further investigation revealed that the generation of much stronger oxidants of hydroxyl radicals (OH) was solely responsible for WO3 layer formation. Quantitative evaluation of OH generation was estimated using a UV–visible spectrophotometer and confirmed that in-situ generation of hydroxyl radicals (OH) could be a main driving force for the high W polishing rate by converting a hard W film into a soft passive film of WO3. WO3 film formation was further confirmed using potentiodynamic polarization studies, which showed a smaller value of corrosion current density (Icorr) in mixed oxidants of Fe(NO3)3 and H2O2 as compared to the large values of Icorr observed for H2O2 alone. This study revealed that a single oxidizer of either Fe(NO3)3 or H2O2 was not capable of achieving a high W removal rate. Rather, only mixed oxidants of Fe(NO3)3 and H2O2 could cause a high W polishing rate due to excessive in-situ generation of OH radicals during the W CMP process.

Availability note (English)

Available from http://dx.doi.org/10.1016/j.apsusc.2020.147862

Additional details

Identifiers

DOI
10.1016/j.apsusc.2020.147862;
PII
S0169433220326192;

Publishing Information

Journal Title
Applied Surface Science
Journal Volume
537
Journal Page Range
vp.
ISSN
0169-4332
CODEN
ASUSEE

INIS

Country of Publication
Netherlands
Country of Input or Organization
International Atomic Energy Agency (IAEA)
INIS RN
54078332
Subject category
S75: CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY;
Descriptors DEI
CURRENT DENSITY; HYDROGEN PEROXIDE; HYDROXYL RADICALS; IRON; LAYERS; NITRATES; NITROGEN OXIDES; OXIDIZERS; PASSIVATION; POLISHING; SLURRIES; TUNGSTATES; TUNGSTEN OXIDES; X-RAY PHOTOELECTRON SPECTROSCOPY
Descriptors DEC
CHALCOGENIDES; DISPERSIONS; ELECTRON SPECTROSCOPY; ELEMENTS; HYDROGEN COMPOUNDS; METALS; MIXTURES; NITROGEN COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; PEROXIDES; PHOTOELECTRON SPECTROSCOPY; RADICALS; REFRACTORY METAL COMPOUNDS; SPECTROSCOPY; SURFACE FINISHING; SUSPENSIONS; TRANSITION ELEMENT COMPOUNDS; TRANSITION ELEMENTS; TUNGSTEN COMPOUNDS

Optional Information

Copyright
Copyright (c) 2020 Elsevier B.V. All rights reserved.