NF3 in Microchips May be the Missing Greenhouse Gas

A chemical widely used to manufacture microchips and flat-screen monitors and televisions has 17,000 times the greenhouse effect of carbon dioxide, but remains unregulated under domestic laws or international treaties, a team of atmospheric chemists from the University of California-Irvine has warned, in a paper published in the journal Geophysical Research Letters.

The chemical in question is known as nitrogen trifluoride (NF3), and researchers Michael J. Prather and Juno Hsu have called it the “missing greenhouse gas.” Formerly used only in small quantities to make microchips, NF3 has become a major product due to its use in the liquid crystal displays of flat-screen televisions and computer monitors. Global production is expected to reach 8,000 tons per year by 2010, which could have a global warming effect equivalent to 130 million metric tons of carbon dioxide.
NF3 was actually originally introduced into microchips in part to fight global warming. In 1997, when the international Kyoto Protocol global warming treaty was drafted, microchips were still manufactured using perfluorocarbons (PFCs). The Kyoto Protocol required reductions in the six major greenhouse gases at the time: carbon dioxide, methane, PFCs, nitrous oxide, hydrofluorocarbons and sulfur hexafluoride. Because NF3 was used in such small quantities, it was not deemed necessary to include it in the treaty.

Semiconductor manufacturers decided that NF3 would make a good substitute for PFCs, even though NF3 has a much larger greenhouse effect. The rationale was that while two-thirds of PFCs escape into the atmosphere during manufacturing, studies showed that only 2 percent of NF3s escape during the same process.

Prather has challenged these numbers, noting that NF3 is “a slippery gas,” capable of escaping not only during manufacturing but also during transport, application or disposal.

“We don’t know if 1 percent is getting out or 20 percent is getting out,” he said. “But once you let the genie out of the bottle, you can’t get it back in.”

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