Patent attributes
A method of etching a silicon oxide film with high precision at high selectivity as compared with a silicon nitride film while establishing both of a higher etching rate of the silicon oxide film and a lower etching rate of the silicon nitride film is provided. An etching method according to the present invention is directed to a dry etching method for etching a film structure without using plasma in which an end of a film layer having a silicon oxide film vertically sandwiched between silicon nitride films and laminated and formed in advance on a wafer disposed in a processing chamber forms a side wall of a groove or a hole while a processing gas is supplied into the processing chamber, the method including the steps of: supplying a hydrogen fluoride gas; cooling the wafer to a low temperature of −30° C. or lower, preferably, to −30 to −60° C.; and etching the silicon oxide film laterally from the end.
