2.12 Industrial Applications of Fluorine Chemistry in Plasma Etch Gases

Abstract

Reactive ion etching is a key technology in the production of advanced semiconductor devices with a resolution of down to sub-10-nm scales. Depending on the exact application, NF3, SF6 as well as complex fluoro(hydro)carbons are used to generate a plasma consisting of ions and other reactive species which converts silicon and its derivatives into volatile compounds. Recently, the development objectives of new etch gases have moved from pure performance to a more complex set of properties including low global warming potential (GWP) and compliance with regulation on fluoroorganic compounds (PFAS). The structure of fluorinated etch gases with low GWP incorporates chemically "weak spots" facilitating atmospheric degradation. The fragmentation in the energetic plasma environment can be predicted by computational methods, enabling the optimization of the ion composition for high etch rate or selectivity between different materials.