Nitrogen trifluoride
Names | |
---|---|
IUPAC name
Nitrogen trifluoride
| |
Other names
Nitrogen fluoride
Trifluoramine Trifluorammonia | |
Identifiers | |
3D model (
JSmol ) |
|
ChEBI | |
ChemSpider | |
ECHA InfoCard
|
100.029.097 |
EC Number |
|
1551 | |
PubChem CID
|
|
RTECS number
|
|
UNII | |
UN number | 2451 |
CompTox Dashboard (EPA)
|
|
| |
| |
Properties | |
NF3 | |
Molar mass | 71.00 g/mol |
Appearance | colorless gas |
Odor | moldy |
Density | 3.003 kg/m3 (1 atm, 15 °C) 1.885 g/cm3 (liquid at b.p.) |
Melting point | −207.15 °C (−340.87 °F; 66.00 K) |
Boiling point | −129.06 °C (−200.31 °F; 144.09 K) |
0.021 g/100 mL | |
Vapor pressure | 44.0 atm[1](−38.5 °F or −39.2 °C or 234.0 K)[a] |
Refractive index (nD)
|
1.0004 |
Structure | |
trigonal pyramidal | |
0.234 D | |
Thermochemistry | |
Heat capacity (C)
|
53.26 J/(mol·K) |
Std molar
entropy (S⦵298) |
260.3 J/(mol·K) |
Std enthalpy of (ΔfH⦵298)formation |
−31.4 kcal/mol[2] −109 kJ/mol[3] |
Gibbs free energy (ΔfG⦵)
|
−84.4 kJ/mol |
Hazards | |
GHS labelling: | |
H270, H280, H332 | |
P220, P244, P260, P304+P340, P315, P370+P376, P403 | |
NFPA 704 (fire diamond) | |
Flash point | Non-flammable |
Lethal dose or concentration (LD, LC): | |
LC50 (median concentration)
|
2000 ppm (mouse, 4 h) 9600 ppm (dog, 1 h) 7500 ppm (monkey, 1 h) 6700 ppm (rat, 1 h) 7500 ppm (mouse, 1 h)[5] |
NIOSH (US health exposure limits): | |
PEL (Permissible)
|
TWA 10 ppm (29 mg/m3)[4] |
REL (Recommended)
|
TWA 10 ppm (29 mg/m3)[4] |
IDLH (Immediate danger) |
1000 ppm[4] |
Safety data sheet (SDS) | AirLiquide |
Related compounds | |
Other anions
|
nitrogen trichloride nitrogen tribromide nitrogen triiodide ammonia |
Other cations
|
phosphorus trifluoride arsenic trifluoride antimony trifluoride bismuth trifluoride |
Related binary fluoro-azanes
|
tetrafluorohydrazine |
Related compounds
|
dinitrogen difluoride |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
Nitrogen trifluoride (NF
3) is an
Synthesis and reactivity
Nitrogen trifluoride did not exist in significant quantities on Earth prior to its synthesis by humans. It is a rare example of a binary fluoride that can be prepared directly from the elements only at very uncommon conditions, such as an electric discharge.
NF
3 is slightly soluble in water without undergoing chemical reaction. It is nonbasic with a low
Similar to
- 2 NF3 + 6 HCl → 6 HF + N2 + 3 Cl2
However, it only attacks (explosively) organic compounds at high temperatures. Consequently it is compatible under standard conditions with several plastics, as well as steel and Monel.[11]
Above 200-300 °C, NF3 radicalizes to nitrogen difluoride and free fluorine radicals. In the presence of metals to remove the fluorine radicals, the mixture cools to give tetrafluorohydrazine:
- 2 NF3 + Cu → N2F4 + CuF2
NF3 reacts with fluorine and antimony pentafluoride to give the tetrafluoroammonium salt:[11]
- NF3 + F2 + SbF5 → NF+
4SbF−
6
Mixtures of NF3 and
Applications
Etching
Nitrogen trifluoride is primarily used to remove
3 is also widely used to clean PECVD
NF
3 dissociates more readily within a low-pressure discharge in comparison to perfluorinated compounds (PFCs) and sulfur hexafluoride (SF
6). The greater abundance of negatively-charged free radicals thus generated can yield higher silicon removal rates, and provide other process benefits such as less residual contamination and a lower net charge stress on the device being fabricated. As a somewhat more thoroughly consumed etching and cleaning agent, NF3 has also been promoted as an environmentally preferable substitute for SF
6 or PFCs such as hexafluoroethane.[14]
The utilization efficiency of the chemicals applied in plasma processes varies widely between equipment and applications. A sizeable fraction of the reactants are wasted into the exhaust stream and can ultimately be emitted into Earth's atmosphere. Modern abatement systems can substantially decrease atmospheric emissions.[15] NF
3 has not been subject to significant use restrictions. The annual reporting of NF
3 production, consumption, and waste emissions by large manufacturers has been required in many industrialized countries as a response to the observed atmospheric growth and the international Kyoto Protocol.[16]
Highly toxic fluorine gas (F2, diatomic fluorine) is a climate neutral replacement for nitrogen trifluoride in some manufacturing applications. It requires more stringent handling and safety precautions, especially to protect manufacturing personnel.[17]
Nitrogen trifluoride is also used in hydrogen fluoride and deuterium fluoride lasers, which are types of chemical lasers. There it is also preferred to fluorine gas due to its more convenient handling properties
Greenhouse gas
NF
3 is a greenhouse gas, with a global warming potential (GWP) 17,200 times greater than that of CO
2 when compared over a 100-year period.[18][19][20] Its GWP place it second only to SF
6 in the group of Kyoto-recognised greenhouse gases, and NF
3 was included in that grouping with effect from 2013 and the commencement of the second commitment period of the Kyoto Protocol. It has an estimated atmospheric lifetime of 740 years,[18] although other work suggests a slightly shorter lifetime of 550 years (and a corresponding GWP of 16,800).[21]
Although NF
3 has a high GWP, for a long time its
Since 1992, when less than 100 tons were produced, production has grown to an estimated 4000 tons in 2007 and is projected to increase significantly.
3 is released into the atmosphere.[23][24] Robson projected that the maximum atmospheric concentration is less than 0.16 parts per trillion (ppt) by volume, which will provide less than 0.001 Wm−2 of IR forcing.[25]
The
Safety
Skin contact with NF
3 is not hazardous, and it is a relatively minor irritant to
See also
- IPCC list of greenhouse gases
- Nitrogen pentafluoride
- Tetrafluorohydrazine
Notes
- critical temperature – below ordinary room temperature.
References
- ^ Air Products; Physical Properties for Nitrogen Trifluoride
- .
- ^ Inorganic Chemistry, p. 462, at Google Books
- ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0455". National Institute for Occupational Safety and Health (NIOSH).
- ^ "Nitrogen trifluoride". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
- ^ Richard Conniff (2008-11-13). "The Greenhouse Gas That Nobody Knew". Yale School of Environment.
- ^ a b "Climate Change Indicators: Atmospheric Concentrations of Greenhouse Gases - Figure 4". U.S. Environmental Protection Agency. 27 June 2016. Retrieved 2021-03-05.
- ^ a b "Atmospheric Flask NF3". National Oceanic and Atmospheric Administration. 2020-06-30.
- ISBN 978-1-56700-041-2.
- doi:10.1002/zaac.19281720132.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - ^ Article Online Posting Date: December 4, 2000
- .
- ^ Parry, Robert W., and Thomas C. Bissot. "The Preparation and Properties of Phosphorus Trifluoride-Borane and Phosphorus Trifluoride-Borane-d31." Journal of the American Chemical Society 78, no. 8 (1956): 1524-1527.
- .
- ^ "F-GHG Emissions Reduction Efforts: Flat Panel Display Supplier Profiles" (PDF). U.S. EPA. 2016-09-30.
- ^ "Fluorinated Greenhouse Gas Emissions and Supplies Reported to the Greenhouse Gas Reporting Program (GHGRP)". U.S. Environmental Protection Agency. 27 September 2015. Retrieved 2021-03-05.
- ^ J. Oshinowo; A. Riva; M Pittroff; T. Schwarze; R. Wieland (2009). "Etch performance of Ar/N2/F2 for CVD/ALD chamber clean". Solid State Technology. 52 (2): 20–24.
- ^ a b "Climate Change 2007: The Physical Sciences Basis" (PDF). IPCC. Retrieved 2008-07-03.
{{cite journal}}
: Cite journal requires|journal=
(help) - .
- ^ Richard Morgan (2008-09-01). "Beyond Carbon: Scientists Worry About Nitrogen's Effects". The New York Times. Archived from the original on 2018-01-23. Retrieved 2008-09-07.
- ^ .
- PMID 18378075.
- ^ M. Roosevelt (2008-07-08). "A climate threat from flat TVs, microchips". Los Angeles Times.
- .
- ^ Robson, Jon. "Nitrogen trifluoride (NF3)". Royal Meteorological Society. Archived from the original on May 16, 2008. Retrieved 2008-10-27.
{{cite journal}}
: Cite journal requires|journal=
(help) - PMID 23341630.
- PMID 21067246.
- ^ Rivers, Ali (2012-08-15). "Nitrogen trifluoride: the new mandatory Kyoto Protocol greenhouse gas". Ecometrica.com. www.ecometrica.com.
- ^ Malik, Yogender (2008-07-03). "Nitrogen trifluoride – Cleaning up in electronic applications". Gasworld. Archived from the original on 2008-08-04. Retrieved 2008-07-15.
- ^ "Immediately Dangerous to Life or Health Concentrations (IDLH): Nitrogen Trifluoride". National Institute for Occupational Safety and Health. 2 November 2018.
External links
- National Pollutant Inventory – Fluoride and compounds fact sheet at the Wayback Machine (archived December 22, 2003)
- NF3 Code of Practice (European Industrial Gas Association)]
- WebBook page for NF3
- CDC - NIOSH Pocket Guide to Chemical Hazards