W deposition and titanium fluoride formation during WF{sub 6} reduction by Ti: Reaction path and mechanisms

Journal Article · Mon Feb 01 04:00:00 EST 1999 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.369174· OSTI ID:302892

Ramanath, G; Greene, J E; Carlsson, J R; Allen, L H ^[1]; Hornback, V C; Allman, D J ^[2]

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1. Coordinated Science Laboratory, Materials Research Laboratory, and Department of Materials Science, University of Illinois, 1304 West Green Street, Urbana, Illinois 61801 (United States)
2. Symbios Logic Incorporated, 1635 Aeroplaza Drive, Colorado Springs, Colorado 80219 (United States)

Reaction of WF{sub 6} with air-exposed 27- and 250-nm-thick Ti films has been studied using Rutherford backscattering spectroscopy, scanning and high-resolution transmission electron microscopy, electron and x-ray diffraction, and x-ray photoelectron spectroscopy. We show that W nucleates and grows rapidly at localized sites on Ti during short WF{sub 6} exposures ({approx}6 s) at 445{degree}C at low partial pressures p{sub WF{sub 6}}{lt}0.2 Torr. Large amounts of F, up to {approx}2.0{times}10{sup 17} atoms/cm{sup 2} corresponding to an average F/Ti ratio of 1.5 in a 27-nm-thick Ti layer, penetrate the Ti film, forming a solid solution and nonvolatile TiF{sub 3}. The large stresses developed due to volume expansion during fluorination of the Ti layer result in local delamination at the W/Ti and the Ti/SiO{sub 2} interfaces at low and high WF{sub 6} exposures, respectively. WF{sub 6} exposure at p{sub WF{sub 6}}{gt}0.35 results in the formation of a network of elongated microcracks in the W film which allow WF{sub 6} to diffuse through and attack the underlying Ti, consuming the 27-nm-thick Ti film through the evolution of gaseous TiF{sub 4}. {copyright} {ital 1999 American Institute of Physics.} thinsp

• OSTI ID: 302892
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 3 Vol. 85; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
CHEMICAL REACTIONS
CHEMICAL VAPOR DEPOSITION
ELECTRON DIFFRACTION
INTERFACES
PHOTOELECTRON SPECTROSCOPY
RUTHERFORD SCATTERING
SCANNING ELECTRON MICROSCOPY
SILICON OXIDES
STRESSES
TITANIUM
TRANSMISSION ELECTRON MICROSCOPY
TUNGSTEN
TUNGSTEN FLUORIDES
X-RAY DIFFRACTION