Process for the active removal of silicum dioxide

摘要

The method involves bringing a sample (1) to be treated, containing SiO2, into a receptacle (2) having at least one gas inlet opening (3) and a gas outlet opening (4). Controllable valves (5) are used to supply measured quantities of fluorine acid gas and steam into the receptacle. The gases fed into the receptacle reach to the silicon dioxide in the sample in sufficient quantity for etching. However the gases are limited such that condensation of the steam into fluid water on the sample during the etching process is reduced. An etching process is then carried out. Steam which is produced as a reaction product by etching is removed before the appearance of condensation through the gas outlet opening. At the same time, an inert gas, e.g. N2, is fed into the receptacle through the gas inlet. These steps are all repeated as often as required.