Safe method for etching silicon dioxide

摘要

Anhydrous ammonium fluoride is used as a safe source of hydrogen fluoride for etching native or other silicon dioxide layers from silicon substrates. Heating the anhydrous ammonium fluoride above its sublimation temperature results in the generation of hydrogen fluoride gas which etches the silicon dioxide. Controlled amounts of water vapor are used during the etch reaction to ensure complete etching of the thin oxide layers down to within hundredths of a monolayer and to achieve precise etch rate control.