More observations on selectivity loss during tungsten CVD

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5684627

Creighton, J R; Rogers, Jr, J W

X-ray photoelectron spectroscopy (XPS) was used to investigate a mechanism for selectivity loss during tungsten CVD which involves the formation and disproportionation of tungsten subfluorides. The subfluorides were formed by flowing WF/sub 6/ over a tungsten foil held at 600 to 700/sup 0/C causing a nearby room temperature SiO/sub 2/-covered silicon sample to become covered with a tungsten-fluorine compound. XPS analysis of this film revealed that the W(4d/sub 5/2/) electron binding energy was intermediate between that of metallic tungsten and WF/sub 6/, indicating the compound was a tungsten subfluoride. Upon heating to greater than or equal to500/sup 0/C, the W(4d/sub 5/2/) electron binding energy shifted to 243.5 eV which is characteristic of metallic tungsten. Also, the F(1s) XPS intensity decreased to a very low level. Results corroborate earlier work indicating that such tungsten subfluoride overlayers disproportionate at approx.300/sup 0/C into WF/sub 6/ which desorbs, and metallic tungsten which remains on the surface. The metallic tungsten may then ''catalyze'' the hydrogen reduction of WF/sub 6/, thus initiating selectivity loss. 13 refs., 2 figs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5684627
• Report Number(s): SAND-87-0093C; CONF-8710225-1; ON: DE88002639
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
ALLOYS
BINDING ENERGY
CHALCOGENIDES
CHEMICAL COATING
CHEMICAL REACTIONS
CHEMICAL VAPOR DEPOSITION
DEPOSITION
DESORPTION
ELECTRONIC STRUCTURE
ELECTRONS
ELEMENTARY PARTICLES
ELEMENTS
ENERGY
FERMIONS
FILMS
FLUORIDES
FLUORINE COMPOUNDS
FOILS
HALIDES
HALOGEN COMPOUNDS
HEAT TREATMENTS
LAYERS
LEPTONS
METALS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
REDUCTION
REFRACTORY METAL COMPOUNDS
REFRACTORY METALS
SILICON COMPOUNDS
SILICON OXIDES
SPECTRA
SUBSTRATES
SURFACE COATING
TEMPERATURE EFFECTS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNGSTEN
TUNGSTEN COMPOUNDS
TUNGSTEN FLUORIDES