Perfluoromethane

Perfluoromethane, also known as carbon tetrafluoride (CF4), is the simplest member of the perfluorocarbons. It is a colorless, odorless, nonflammable gas with exceptional chemical inertness due to strong carbon–fluorine bonds. The molecule has a tetrahedral geometry; its molar mass is 88.0 g/mol. At room temperature CF4 is a gas; its boiling point is −128.0°C and its melting point is about −183.6°C. It has a density near 3.7 kg/m3 and is insoluble in water.

Production and applications: CF4 is produced industrially by direct fluorination of methane or carbon tetrachloride. It is used primarily as a fluorine source in plasma etching and reactive ion etching in the semiconductor and microfabrication industries, especially for silicon dioxide and silicon nitride. It is also employed as a tracer gas in some leak-detection applications and as a fill gas in specialized electronic equipment.

Environmental and safety aspects: CF4 is a potent greenhouse gas with a long atmospheric lifetime, contributing to climate change. Its global warming potential over 100 years is around 7,000, and its atmospheric lifetime is on the order of tens of thousands of years. It is regulated under international climate agreements, and emissions are subject to reporting in many jurisdictions. In terms of safety, CF4 is non-toxic at typical exposure levels and non-flammable, but high concentrations can act as an asphyxiant in poorly ventilated areas.