| 摘要 |
PROBLEM TO BE SOLVED: To target an etchant of a silicon nitride film using a phosphoric acid aqueous solution, and very easily remove silicon compounds produced in the etchant to make it further suitable for an industrial process, and reduce regeneration expenses of the etchant. SOLUTION: A method for regenerating this etchant has a step in which, in the method for regenerating the etchant which is used for etching the silicon nitride film in an etching bath and is composed of the phosphoric acid aqueous solution, the etchant containing the silicon compound caused by etching is removed from the etching bath, and water is added to the removed etchant to lower the phosphoric acid concentration of the etchant down to 50 to 80 wt%, and a step of removing the silicon compound precipitated in the etchant due to reduction in the phosphoric acid concentration from the etchant. COPYRIGHT: (C)2004,JPO
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