Patent attributes
A wafer etching and impurity analysis method is presented in which a wafer is held in a vessel having gas introduction and exhaust ports, a solution including a mixture of hydrofluoric acid and nitric acid alone or together with sulfuric acid is bubbled with a carrier gas without being heated, which generates a gas containing vaporized hydrofluoric acid and nitric acid, and the inside of the vessel is purged so that the amount of gas supplied is kept constant at all times. All or a specific portion of the wafer is cooled to a specific temperature. Consequently, the gas is condensed on the surface of the wafer, which allows the required portion of the wafer to be etched. The method reduces the amount of liquid needed for residue recovery, the amount of admixed silicon during impurity analysis, and the concentration time.
