US Patent 7083741 Process and device for the wet-chemical treatment of silicon

A device and process for the wet-chemical treatment of silicon using an etching liquid that contains water, nitric acid and hydrofluoric acid. The etching liquid is activated by introducing nitrogen oxide (NOx) into the etching liquid, before being used for the wet-chemical treatment of silicon. The device consists of a first vessel in which silicon is subjected to a wet-chemical treatment with the aid of an etching liquid, a second vessel in which fresh etching liquid is held ready, and a connecting line between the first vessel and the second vessel, through which nitrogen oxides (NOx) formed in the first vessel during the wet-chemical treatment are passed to the second vessel.